qemu

qcow2.c (210153B)

---

 /*
  * Block driver for the QCOW version 2 format
  *
  * Copyright (c) 2004-2006 Fabrice Bellard
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 
 #include "qemu/osdep.h"
 
 #include "block/qdict.h"
 #include "sysemu/block-backend.h"
 #include "qemu/main-loop.h"
 #include "qemu/module.h"
 #include "qcow2.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "qapi/qapi-events-block-core.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qstring.h"
 #include "trace.h"
 #include "qemu/option_int.h"
 #include "qemu/cutils.h"
 #include "qemu/bswap.h"
 #include "qemu/memalign.h"
 #include "qapi/qobject-input-visitor.h"
 #include "qapi/qapi-visit-block-core.h"
 #include "crypto.h"
 #include "block/aio_task.h"
 
 /*
   Differences with QCOW:
 
   - Support for multiple incremental snapshots.
   - Memory management by reference counts.
   - Clusters which have a reference count of one have the bit
     QCOW_OFLAG_COPIED to optimize write performance.
   - Size of compressed clusters is stored in sectors to reduce bit usage
     in the cluster offsets.
   - Support for storing additional data (such as the VM state) in the
     snapshots.
   - If a backing store is used, the cluster size is not constrained
     (could be backported to QCOW).
   - L2 tables have always a size of one cluster.
 */
 
 
 typedef struct {
     uint32_t magic;
     uint32_t len;
 } QEMU_PACKED QCowExtension;
 
 #define  QCOW2_EXT_MAGIC_END 0
 #define  QCOW2_EXT_MAGIC_BACKING_FORMAT 0xe2792aca
 #define  QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
 #define  QCOW2_EXT_MAGIC_CRYPTO_HEADER 0x0537be77
 #define  QCOW2_EXT_MAGIC_BITMAPS 0x23852875
 #define  QCOW2_EXT_MAGIC_DATA_FILE 0x44415441
 
 static int coroutine_fn
 qcow2_co_preadv_compressed(BlockDriverState *bs,
                            uint64_t l2_entry,
                            uint64_t offset,
                            uint64_t bytes,
                            QEMUIOVector *qiov,
                            size_t qiov_offset);
 
 static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
     const QCowHeader *cow_header = (const void *)buf;
 
     if (buf_size >= sizeof(QCowHeader) &&
         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
         be32_to_cpu(cow_header->version) >= 2)
         return 100;
     else
         return 0;
 }
 
 
 static int qcow2_crypto_hdr_read_func(QCryptoBlock *block, size_t offset,
                                       uint8_t *buf, size_t buflen,
                                       void *opaque, Error **errp)
 {
     BlockDriverState *bs = opaque;
     BDRVQcow2State *s = bs->opaque;
     ssize_t ret;
 
     if ((offset + buflen) > s->crypto_header.length) {
         error_setg(errp, "Request for data outside of extension header");
         return -1;
     }
 
     ret = bdrv_pread(bs->file, s->crypto_header.offset + offset, buflen, buf,
                      0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not read encryption header");
         return -1;
     }
     return 0;
 }
 
 
 static int qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
                                       void *opaque, Error **errp)
 {
     BlockDriverState *bs = opaque;
     BDRVQcow2State *s = bs->opaque;
     int64_t ret;
     int64_t clusterlen;
 
     ret = qcow2_alloc_clusters(bs, headerlen);
     if (ret < 0) {
         error_setg_errno(errp, -ret,
                          "Cannot allocate cluster for LUKS header size %zu",
                          headerlen);
         return -1;
     }
 
     s->crypto_header.length = headerlen;
     s->crypto_header.offset = ret;
 
     /*
      * Zero fill all space in cluster so it has predictable
      * content, as we may not initialize some regions of the
      * header (eg only 1 out of 8 key slots will be initialized)
      */
     clusterlen = size_to_clusters(s, headerlen) * s->cluster_size;
     assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen, false) == 0);
     ret = bdrv_pwrite_zeroes(bs->file,
                              ret,
                              clusterlen, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not zero fill encryption header");
         return -1;
     }
 
     return 0;
 }
 
 
 static int qcow2_crypto_hdr_write_func(QCryptoBlock *block, size_t offset,
                                        const uint8_t *buf, size_t buflen,
                                        void *opaque, Error **errp)
 {
     BlockDriverState *bs = opaque;
     BDRVQcow2State *s = bs->opaque;
     ssize_t ret;
 
     if ((offset + buflen) > s->crypto_header.length) {
         error_setg(errp, "Request for data outside of extension header");
         return -1;
     }
 
     ret = bdrv_pwrite(bs->file, s->crypto_header.offset + offset, buflen, buf,
                       0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not read encryption header");
         return -1;
     }
     return 0;
 }
 
 static QDict*
 qcow2_extract_crypto_opts(QemuOpts *opts, const char *fmt, Error **errp)
 {
     QDict *cryptoopts_qdict;
     QDict *opts_qdict;
 
     /* Extract "encrypt." options into a qdict */
     opts_qdict = qemu_opts_to_qdict(opts, NULL);
     qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, "encrypt.");
     qobject_unref(opts_qdict);
     qdict_put_str(cryptoopts_qdict, "format", fmt);
     return cryptoopts_qdict;
 }
 
 /*
  * read qcow2 extension and fill bs
  * start reading from start_offset
  * finish reading upon magic of value 0 or when end_offset reached
  * unknown magic is skipped (future extension this version knows nothing about)
  * return 0 upon success, non-0 otherwise
  */
 static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
                                  uint64_t end_offset, void **p_feature_table,
                                  int flags, bool *need_update_header,
                                  Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     QCowExtension ext;
     uint64_t offset;
     int ret;
     Qcow2BitmapHeaderExt bitmaps_ext;
 
     if (need_update_header != NULL) {
         *need_update_header = false;
     }
 
 #ifdef DEBUG_EXT
     printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
 #endif
     offset = start_offset;
     while (offset < end_offset) {
 
 #ifdef DEBUG_EXT
         /* Sanity check */
         if (offset > s->cluster_size)
             printf("qcow2_read_extension: suspicious offset %lu\n", offset);
 
         printf("attempting to read extended header in offset %lu\n", offset);
 #endif
 
         ret = bdrv_pread(bs->file, offset, sizeof(ext), &ext, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "qcow2_read_extension: ERROR: "
                              "pread fail from offset %" PRIu64, offset);
             return 1;
         }
         ext.magic = be32_to_cpu(ext.magic);
         ext.len = be32_to_cpu(ext.len);
         offset += sizeof(ext);
 #ifdef DEBUG_EXT
         printf("ext.magic = 0x%x\n", ext.magic);
 #endif
         if (offset > end_offset || ext.len > end_offset - offset) {
             error_setg(errp, "Header extension too large");
             return -EINVAL;
         }
 
         switch (ext.magic) {
         case QCOW2_EXT_MAGIC_END:
             return 0;
 
         case QCOW2_EXT_MAGIC_BACKING_FORMAT:
             if (ext.len >= sizeof(bs->backing_format)) {
                 error_setg(errp, "ERROR: ext_backing_format: len=%" PRIu32
                            " too large (>=%zu)", ext.len,
                            sizeof(bs->backing_format));
                 return 2;
             }
             ret = bdrv_pread(bs->file, offset, ext.len, bs->backing_format, 0);
             if (ret < 0) {
                 error_setg_errno(errp, -ret, "ERROR: ext_backing_format: "
                                  "Could not read format name");
                 return 3;
             }
             bs->backing_format[ext.len] = '\0';
             s->image_backing_format = g_strdup(bs->backing_format);
 #ifdef DEBUG_EXT
             printf("Qcow2: Got format extension %s\n", bs->backing_format);
 #endif
             break;
 
         case QCOW2_EXT_MAGIC_FEATURE_TABLE:
             if (p_feature_table != NULL) {
                 void *feature_table = g_malloc0(ext.len + 2 * sizeof(Qcow2Feature));
                 ret = bdrv_pread(bs->file, offset, ext.len, feature_table, 0);
                 if (ret < 0) {
                     error_setg_errno(errp, -ret, "ERROR: ext_feature_table: "
                                      "Could not read table");
                     g_free(feature_table);
                     return ret;
                 }
 
                 *p_feature_table = feature_table;
             }
             break;
 
         case QCOW2_EXT_MAGIC_CRYPTO_HEADER: {
             unsigned int cflags = 0;
             if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
                 error_setg(errp, "CRYPTO header extension only "
                            "expected with LUKS encryption method");
                 return -EINVAL;
             }
             if (ext.len != sizeof(Qcow2CryptoHeaderExtension)) {
                 error_setg(errp, "CRYPTO header extension size %u, "
                            "but expected size %zu", ext.len,
                            sizeof(Qcow2CryptoHeaderExtension));
                 return -EINVAL;
             }
 
             ret = bdrv_pread(bs->file, offset, ext.len, &s->crypto_header, 0);
             if (ret < 0) {
                 error_setg_errno(errp, -ret,
                                  "Unable to read CRYPTO header extension");
                 return ret;
             }
             s->crypto_header.offset = be64_to_cpu(s->crypto_header.offset);
             s->crypto_header.length = be64_to_cpu(s->crypto_header.length);
 
             if ((s->crypto_header.offset % s->cluster_size) != 0) {
                 error_setg(errp, "Encryption header offset '%" PRIu64 "' is "
                            "not a multiple of cluster size '%u'",
                            s->crypto_header.offset, s->cluster_size);
                 return -EINVAL;
             }
 
             if (flags & BDRV_O_NO_IO) {
                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
             }
             s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
                                            qcow2_crypto_hdr_read_func,
                                            bs, cflags, QCOW2_MAX_THREADS, errp);
             if (!s->crypto) {
                 return -EINVAL;
             }
         }   break;
 
         case QCOW2_EXT_MAGIC_BITMAPS:
             if (ext.len != sizeof(bitmaps_ext)) {
                 error_setg_errno(errp, -ret, "bitmaps_ext: "
                                  "Invalid extension length");
                 return -EINVAL;
             }
 
             if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS)) {
                 if (s->qcow_version < 3) {
                     /* Let's be a bit more specific */
                     warn_report("This qcow2 v2 image contains bitmaps, but "
                                 "they may have been modified by a program "
                                 "without persistent bitmap support; so now "
                                 "they must all be considered inconsistent");
                 } else {
                     warn_report("a program lacking bitmap support "
                                 "modified this file, so all bitmaps are now "
                                 "considered inconsistent");
                 }
                 error_printf("Some clusters may be leaked, "
                              "run 'qemu-img check -r' on the image "
                              "file to fix.");
                 if (need_update_header != NULL) {
                     /* Updating is needed to drop invalid bitmap extension. */
                     *need_update_header = true;
                 }
                 break;
             }
 
             ret = bdrv_pread(bs->file, offset, ext.len, &bitmaps_ext, 0);
             if (ret < 0) {
                 error_setg_errno(errp, -ret, "bitmaps_ext: "
                                  "Could not read ext header");
                 return ret;
             }
 
             if (bitmaps_ext.reserved32 != 0) {
                 error_setg_errno(errp, -ret, "bitmaps_ext: "
                                  "Reserved field is not zero");
                 return -EINVAL;
             }
 
             bitmaps_ext.nb_bitmaps = be32_to_cpu(bitmaps_ext.nb_bitmaps);
             bitmaps_ext.bitmap_directory_size =
                 be64_to_cpu(bitmaps_ext.bitmap_directory_size);
             bitmaps_ext.bitmap_directory_offset =
                 be64_to_cpu(bitmaps_ext.bitmap_directory_offset);
 
             if (bitmaps_ext.nb_bitmaps > QCOW2_MAX_BITMAPS) {
                 error_setg(errp,
                            "bitmaps_ext: Image has %" PRIu32 " bitmaps, "
                            "exceeding the QEMU supported maximum of %d",
                            bitmaps_ext.nb_bitmaps, QCOW2_MAX_BITMAPS);
                 return -EINVAL;
             }
 
             if (bitmaps_ext.nb_bitmaps == 0) {
                 error_setg(errp, "found bitmaps extension with zero bitmaps");
                 return -EINVAL;
             }
 
             if (offset_into_cluster(s, bitmaps_ext.bitmap_directory_offset)) {
                 error_setg(errp, "bitmaps_ext: "
                                  "invalid bitmap directory offset");
                 return -EINVAL;
             }
 
             if (bitmaps_ext.bitmap_directory_size >
                 QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
                 error_setg(errp, "bitmaps_ext: "
                                  "bitmap directory size (%" PRIu64 ") exceeds "
                                  "the maximum supported size (%d)",
                                  bitmaps_ext.bitmap_directory_size,
                                  QCOW2_MAX_BITMAP_DIRECTORY_SIZE);
                 return -EINVAL;
             }
 
             s->nb_bitmaps = bitmaps_ext.nb_bitmaps;
             s->bitmap_directory_offset =
                     bitmaps_ext.bitmap_directory_offset;
             s->bitmap_directory_size =
                     bitmaps_ext.bitmap_directory_size;
 
 #ifdef DEBUG_EXT
             printf("Qcow2: Got bitmaps extension: "
                    "offset=%" PRIu64 " nb_bitmaps=%" PRIu32 "\n",
                    s->bitmap_directory_offset, s->nb_bitmaps);
 #endif
             break;
 
         case QCOW2_EXT_MAGIC_DATA_FILE:
         {
             s->image_data_file = g_malloc0(ext.len + 1);
             ret = bdrv_pread(bs->file, offset, ext.len, s->image_data_file, 0);
             if (ret < 0) {
                 error_setg_errno(errp, -ret,
                                  "ERROR: Could not read data file name");
                 return ret;
             }
 #ifdef DEBUG_EXT
             printf("Qcow2: Got external data file %s\n", s->image_data_file);
 #endif
             break;
         }
 
         default:
             /* unknown magic - save it in case we need to rewrite the header */
             /* If you add a new feature, make sure to also update the fast
              * path of qcow2_make_empty() to deal with it. */
             {
                 Qcow2UnknownHeaderExtension *uext;
 
                 uext = g_malloc0(sizeof(*uext)  + ext.len);
                 uext->magic = ext.magic;
                 uext->len = ext.len;
                 QLIST_INSERT_HEAD(&s->unknown_header_ext, uext, next);
 
                 ret = bdrv_pread(bs->file, offset, uext->len, uext->data, 0);
                 if (ret < 0) {
                     error_setg_errno(errp, -ret, "ERROR: unknown extension: "
                                      "Could not read data");
                     return ret;
                 }
             }
             break;
         }
 
         offset += ((ext.len + 7) & ~7);
     }
 
     return 0;
 }
 
 static void cleanup_unknown_header_ext(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     Qcow2UnknownHeaderExtension *uext, *next;
 
     QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) {
         QLIST_REMOVE(uext, next);
         g_free(uext);
     }
 }
 
 static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
                                        uint64_t mask)
 {
     g_autoptr(GString) features = g_string_sized_new(60);
 
     while (table && table->name[0] != '\0') {
         if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
             if (mask & (1ULL << table->bit)) {
                 if (features->len > 0) {
                     g_string_append(features, ", ");
                 }
                 g_string_append_printf(features, "%.46s", table->name);
                 mask &= ~(1ULL << table->bit);
             }
         }
         table++;
     }
 
     if (mask) {
         if (features->len > 0) {
             g_string_append(features, ", ");
         }
         g_string_append_printf(features,
                                "Unknown incompatible feature: %" PRIx64, mask);
     }
 
     error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
 }
 
 /*
  * Sets the dirty bit and flushes afterwards if necessary.
  *
  * The incompatible_features bit is only set if the image file header was
  * updated successfully.  Therefore it is not required to check the return
  * value of this function.
  */
 int qcow2_mark_dirty(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t val;
     int ret;
 
     assert(s->qcow_version >= 3);
 
     if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
         return 0; /* already dirty */
     }
 
     val = cpu_to_be64(s->incompatible_features | QCOW2_INCOMPAT_DIRTY);
     ret = bdrv_pwrite_sync(bs->file,
                            offsetof(QCowHeader, incompatible_features),
                            sizeof(val), &val, 0);
     if (ret < 0) {
         return ret;
     }
 
     /* Only treat image as dirty if the header was updated successfully */
     s->incompatible_features |= QCOW2_INCOMPAT_DIRTY;
     return 0;
 }
 
 /*
  * Clears the dirty bit and flushes before if necessary.  Only call this
  * function when there are no pending requests, it does not guard against
  * concurrent requests dirtying the image.
  */
 static int qcow2_mark_clean(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
 
     if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
         int ret;
 
         s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY;
 
         ret = qcow2_flush_caches(bs);
         if (ret < 0) {
             return ret;
         }
 
         return qcow2_update_header(bs);
     }
     return 0;
 }
 
 /*
  * Marks the image as corrupt.
  */
 int qcow2_mark_corrupt(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
 
     s->incompatible_features |= QCOW2_INCOMPAT_CORRUPT;
     return qcow2_update_header(bs);
 }
 
 /*
  * Marks the image as consistent, i.e., unsets the corrupt bit, and flushes
  * before if necessary.
  */
 int qcow2_mark_consistent(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
 
     if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
         int ret = qcow2_flush_caches(bs);
         if (ret < 0) {
             return ret;
         }
 
         s->incompatible_features &= ~QCOW2_INCOMPAT_CORRUPT;
         return qcow2_update_header(bs);
     }
     return 0;
 }
 
 static void qcow2_add_check_result(BdrvCheckResult *out,
                                    const BdrvCheckResult *src,
                                    bool set_allocation_info)
 {
     out->corruptions += src->corruptions;
     out->leaks += src->leaks;
     out->check_errors += src->check_errors;
     out->corruptions_fixed += src->corruptions_fixed;
     out->leaks_fixed += src->leaks_fixed;
 
     if (set_allocation_info) {
         out->image_end_offset = src->image_end_offset;
         out->bfi = src->bfi;
     }
 }
 
 static int coroutine_fn qcow2_co_check_locked(BlockDriverState *bs,
                                               BdrvCheckResult *result,
                                               BdrvCheckMode fix)
 {
     BdrvCheckResult snapshot_res = {};
     BdrvCheckResult refcount_res = {};
     int ret;
 
     memset(result, 0, sizeof(*result));
 
     ret = qcow2_check_read_snapshot_table(bs, &snapshot_res, fix);
     if (ret < 0) {
         qcow2_add_check_result(result, &snapshot_res, false);
         return ret;
     }
 
     ret = qcow2_check_refcounts(bs, &refcount_res, fix);
     qcow2_add_check_result(result, &refcount_res, true);
     if (ret < 0) {
         qcow2_add_check_result(result, &snapshot_res, false);
         return ret;
     }
 
     ret = qcow2_check_fix_snapshot_table(bs, &snapshot_res, fix);
     qcow2_add_check_result(result, &snapshot_res, false);
     if (ret < 0) {
         return ret;
     }
 
     if (fix && result->check_errors == 0 && result->corruptions == 0) {
         ret = qcow2_mark_clean(bs);
         if (ret < 0) {
             return ret;
         }
         return qcow2_mark_consistent(bs);
     }
     return ret;
 }
 
 static int coroutine_fn qcow2_co_check(BlockDriverState *bs,
                                        BdrvCheckResult *result,
                                        BdrvCheckMode fix)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret;
 
     qemu_co_mutex_lock(&s->lock);
     ret = qcow2_co_check_locked(bs, result, fix);
     qemu_co_mutex_unlock(&s->lock);
     return ret;
 }
 
 int qcow2_validate_table(BlockDriverState *bs, uint64_t offset,
                          uint64_t entries, size_t entry_len,
                          int64_t max_size_bytes, const char *table_name,
                          Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
 
     if (entries > max_size_bytes / entry_len) {
         error_setg(errp, "%s too large", table_name);
         return -EFBIG;
     }
 
     /* Use signed INT64_MAX as the maximum even for uint64_t header fields,
      * because values will be passed to qemu functions taking int64_t. */
     if ((INT64_MAX - entries * entry_len < offset) ||
         (offset_into_cluster(s, offset) != 0)) {
         error_setg(errp, "%s offset invalid", table_name);
         return -EINVAL;
     }
 
     return 0;
 }
 
 static const char *const mutable_opts[] = {
     QCOW2_OPT_LAZY_REFCOUNTS,
     QCOW2_OPT_DISCARD_REQUEST,
     QCOW2_OPT_DISCARD_SNAPSHOT,
     QCOW2_OPT_DISCARD_OTHER,
     QCOW2_OPT_OVERLAP,
     QCOW2_OPT_OVERLAP_TEMPLATE,
     QCOW2_OPT_OVERLAP_MAIN_HEADER,
     QCOW2_OPT_OVERLAP_ACTIVE_L1,
     QCOW2_OPT_OVERLAP_ACTIVE_L2,
     QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
     QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
     QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
     QCOW2_OPT_OVERLAP_INACTIVE_L1,
     QCOW2_OPT_OVERLAP_INACTIVE_L2,
     QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
     QCOW2_OPT_CACHE_SIZE,
     QCOW2_OPT_L2_CACHE_SIZE,
     QCOW2_OPT_L2_CACHE_ENTRY_SIZE,
     QCOW2_OPT_REFCOUNT_CACHE_SIZE,
     QCOW2_OPT_CACHE_CLEAN_INTERVAL,
     NULL
 };
 
 static QemuOptsList qcow2_runtime_opts = {
     .name = "qcow2",
     .head = QTAILQ_HEAD_INITIALIZER(qcow2_runtime_opts.head),
     .desc = {
         {
             .name = QCOW2_OPT_LAZY_REFCOUNTS,
             .type = QEMU_OPT_BOOL,
             .help = "Postpone refcount updates",
         },
         {
             .name = QCOW2_OPT_DISCARD_REQUEST,
             .type = QEMU_OPT_BOOL,
             .help = "Pass guest discard requests to the layer below",
         },
         {
             .name = QCOW2_OPT_DISCARD_SNAPSHOT,
             .type = QEMU_OPT_BOOL,
             .help = "Generate discard requests when snapshot related space "
                     "is freed",
         },
         {
             .name = QCOW2_OPT_DISCARD_OTHER,
             .type = QEMU_OPT_BOOL,
             .help = "Generate discard requests when other clusters are freed",
         },
         {
             .name = QCOW2_OPT_OVERLAP,
             .type = QEMU_OPT_STRING,
             .help = "Selects which overlap checks to perform from a range of "
                     "templates (none, constant, cached, all)",
         },
         {
             .name = QCOW2_OPT_OVERLAP_TEMPLATE,
             .type = QEMU_OPT_STRING,
             .help = "Selects which overlap checks to perform from a range of "
                     "templates (none, constant, cached, all)",
         },
         {
             .name = QCOW2_OPT_OVERLAP_MAIN_HEADER,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into the main qcow2 header",
         },
         {
             .name = QCOW2_OPT_OVERLAP_ACTIVE_L1,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into the active L1 table",
         },
         {
             .name = QCOW2_OPT_OVERLAP_ACTIVE_L2,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into an active L2 table",
         },
         {
             .name = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into the refcount table",
         },
         {
             .name = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into a refcount block",
         },
         {
             .name = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into the snapshot table",
         },
         {
             .name = QCOW2_OPT_OVERLAP_INACTIVE_L1,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into an inactive L1 table",
         },
         {
             .name = QCOW2_OPT_OVERLAP_INACTIVE_L2,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into an inactive L2 table",
         },
         {
             .name = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into the bitmap directory",
         },
         {
             .name = QCOW2_OPT_CACHE_SIZE,
             .type = QEMU_OPT_SIZE,
             .help = "Maximum combined metadata (L2 tables and refcount blocks) "
                     "cache size",
         },
         {
             .name = QCOW2_OPT_L2_CACHE_SIZE,
             .type = QEMU_OPT_SIZE,
             .help = "Maximum L2 table cache size",
         },
         {
             .name = QCOW2_OPT_L2_CACHE_ENTRY_SIZE,
             .type = QEMU_OPT_SIZE,
             .help = "Size of each entry in the L2 cache",
         },
         {
             .name = QCOW2_OPT_REFCOUNT_CACHE_SIZE,
             .type = QEMU_OPT_SIZE,
             .help = "Maximum refcount block cache size",
         },
         {
             .name = QCOW2_OPT_CACHE_CLEAN_INTERVAL,
             .type = QEMU_OPT_NUMBER,
             .help = "Clean unused cache entries after this time (in seconds)",
         },
         BLOCK_CRYPTO_OPT_DEF_KEY_SECRET("encrypt.",
             "ID of secret providing qcow2 AES key or LUKS passphrase"),
         { /* end of list */ }
     },
 };
 
 static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
     [QCOW2_OL_MAIN_HEADER_BITNR]      = QCOW2_OPT_OVERLAP_MAIN_HEADER,
     [QCOW2_OL_ACTIVE_L1_BITNR]        = QCOW2_OPT_OVERLAP_ACTIVE_L1,
     [QCOW2_OL_ACTIVE_L2_BITNR]        = QCOW2_OPT_OVERLAP_ACTIVE_L2,
     [QCOW2_OL_REFCOUNT_TABLE_BITNR]   = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
     [QCOW2_OL_REFCOUNT_BLOCK_BITNR]   = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
     [QCOW2_OL_SNAPSHOT_TABLE_BITNR]   = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
     [QCOW2_OL_INACTIVE_L1_BITNR]      = QCOW2_OPT_OVERLAP_INACTIVE_L1,
     [QCOW2_OL_INACTIVE_L2_BITNR]      = QCOW2_OPT_OVERLAP_INACTIVE_L2,
     [QCOW2_OL_BITMAP_DIRECTORY_BITNR] = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
 };
 
 static void cache_clean_timer_cb(void *opaque)
 {
     BlockDriverState *bs = opaque;
     BDRVQcow2State *s = bs->opaque;
     qcow2_cache_clean_unused(s->l2_table_cache);
     qcow2_cache_clean_unused(s->refcount_block_cache);
     timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
               (int64_t) s->cache_clean_interval * 1000);
 }
 
 static void cache_clean_timer_init(BlockDriverState *bs, AioContext *context)
 {
     BDRVQcow2State *s = bs->opaque;
     if (s->cache_clean_interval > 0) {
         s->cache_clean_timer =
             aio_timer_new_with_attrs(context, QEMU_CLOCK_VIRTUAL,
                                      SCALE_MS, QEMU_TIMER_ATTR_EXTERNAL,
                                      cache_clean_timer_cb, bs);
         timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
                   (int64_t) s->cache_clean_interval * 1000);
     }
 }
 
 static void cache_clean_timer_del(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     if (s->cache_clean_timer) {
         timer_free(s->cache_clean_timer);
         s->cache_clean_timer = NULL;
     }
 }
 
 static void qcow2_detach_aio_context(BlockDriverState *bs)
 {
     cache_clean_timer_del(bs);
 }
 
 static void qcow2_attach_aio_context(BlockDriverState *bs,
                                      AioContext *new_context)
 {
     cache_clean_timer_init(bs, new_context);
 }
 
 static bool read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
                              uint64_t *l2_cache_size,
                              uint64_t *l2_cache_entry_size,
                              uint64_t *refcount_cache_size, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t combined_cache_size, l2_cache_max_setting;
     bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
     bool l2_cache_entry_size_set;
     int min_refcount_cache = MIN_REFCOUNT_CACHE_SIZE * s->cluster_size;
     uint64_t virtual_disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
     uint64_t max_l2_entries = DIV_ROUND_UP(virtual_disk_size, s->cluster_size);
     /* An L2 table is always one cluster in size so the max cache size
      * should be a multiple of the cluster size. */
     uint64_t max_l2_cache = ROUND_UP(max_l2_entries * l2_entry_size(s),
                                      s->cluster_size);
 
     combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE);
     l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE);
     refcount_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
     l2_cache_entry_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE);
 
     combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0);
     l2_cache_max_setting = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE,
                                              DEFAULT_L2_CACHE_MAX_SIZE);
     *refcount_cache_size = qemu_opt_get_size(opts,
                                              QCOW2_OPT_REFCOUNT_CACHE_SIZE, 0);
 
     *l2_cache_entry_size = qemu_opt_get_size(
         opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE, s->cluster_size);
 
     *l2_cache_size = MIN(max_l2_cache, l2_cache_max_setting);
 
     if (combined_cache_size_set) {
         if (l2_cache_size_set && refcount_cache_size_set) {
             error_setg(errp, QCOW2_OPT_CACHE_SIZE ", " QCOW2_OPT_L2_CACHE_SIZE
                        " and " QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not be set "
                        "at the same time");
             return false;
         } else if (l2_cache_size_set &&
                    (l2_cache_max_setting > combined_cache_size)) {
             error_setg(errp, QCOW2_OPT_L2_CACHE_SIZE " may not exceed "
                        QCOW2_OPT_CACHE_SIZE);
             return false;
         } else if (*refcount_cache_size > combined_cache_size) {
             error_setg(errp, QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not exceed "
                        QCOW2_OPT_CACHE_SIZE);
             return false;
         }
 
         if (l2_cache_size_set) {
             *refcount_cache_size = combined_cache_size - *l2_cache_size;
         } else if (refcount_cache_size_set) {
             *l2_cache_size = combined_cache_size - *refcount_cache_size;
         } else {
             /* Assign as much memory as possible to the L2 cache, and
              * use the remainder for the refcount cache */
             if (combined_cache_size >= max_l2_cache + min_refcount_cache) {
                 *l2_cache_size = max_l2_cache;
                 *refcount_cache_size = combined_cache_size - *l2_cache_size;
             } else {
                 *refcount_cache_size =
                     MIN(combined_cache_size, min_refcount_cache);
                 *l2_cache_size = combined_cache_size - *refcount_cache_size;
             }
         }
     }
 
     /*
      * If the L2 cache is not enough to cover the whole disk then
      * default to 4KB entries. Smaller entries reduce the cost of
      * loads and evictions and increase I/O performance.
      */
     if (*l2_cache_size < max_l2_cache && !l2_cache_entry_size_set) {
         *l2_cache_entry_size = MIN(s->cluster_size, 4096);
     }
 
     /* l2_cache_size and refcount_cache_size are ensured to have at least
      * their minimum values in qcow2_update_options_prepare() */
 
     if (*l2_cache_entry_size < (1 << MIN_CLUSTER_BITS) ||
         *l2_cache_entry_size > s->cluster_size ||
         !is_power_of_2(*l2_cache_entry_size)) {
         error_setg(errp, "L2 cache entry size must be a power of two "
                    "between %d and the cluster size (%d)",
                    1 << MIN_CLUSTER_BITS, s->cluster_size);
         return false;
     }
 
     return true;
 }
 
 typedef struct Qcow2ReopenState {
     Qcow2Cache *l2_table_cache;
     Qcow2Cache *refcount_block_cache;
     int l2_slice_size; /* Number of entries in a slice of the L2 table */
     bool use_lazy_refcounts;
     int overlap_check;
     bool discard_passthrough[QCOW2_DISCARD_MAX];
     uint64_t cache_clean_interval;
     QCryptoBlockOpenOptions *crypto_opts; /* Disk encryption runtime options */
 } Qcow2ReopenState;
 
 static int qcow2_update_options_prepare(BlockDriverState *bs,
                                         Qcow2ReopenState *r,
                                         QDict *options, int flags,
                                         Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     QemuOpts *opts = NULL;
     const char *opt_overlap_check, *opt_overlap_check_template;
     int overlap_check_template = 0;
     uint64_t l2_cache_size, l2_cache_entry_size, refcount_cache_size;
     int i;
     const char *encryptfmt;
     QDict *encryptopts = NULL;
     int ret;
 
     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
     encryptfmt = qdict_get_try_str(encryptopts, "format");
 
     opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
         ret = -EINVAL;
         goto fail;
     }
 
     /* get L2 table/refcount block cache size from command line options */
     if (!read_cache_sizes(bs, opts, &l2_cache_size, &l2_cache_entry_size,
                           &refcount_cache_size, errp)) {
         ret = -EINVAL;
         goto fail;
     }
 
     l2_cache_size /= l2_cache_entry_size;
     if (l2_cache_size < MIN_L2_CACHE_SIZE) {
         l2_cache_size = MIN_L2_CACHE_SIZE;
     }
     if (l2_cache_size > INT_MAX) {
         error_setg(errp, "L2 cache size too big");
         ret = -EINVAL;
         goto fail;
     }
 
     refcount_cache_size /= s->cluster_size;
     if (refcount_cache_size < MIN_REFCOUNT_CACHE_SIZE) {
         refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE;
     }
     if (refcount_cache_size > INT_MAX) {
         error_setg(errp, "Refcount cache size too big");
         ret = -EINVAL;
         goto fail;
     }
 
     /* alloc new L2 table/refcount block cache, flush old one */
     if (s->l2_table_cache) {
         ret = qcow2_cache_flush(bs, s->l2_table_cache);
         if (ret) {
             error_setg_errno(errp, -ret, "Failed to flush the L2 table cache");
             goto fail;
         }
     }
 
     if (s->refcount_block_cache) {
         ret = qcow2_cache_flush(bs, s->refcount_block_cache);
         if (ret) {
             error_setg_errno(errp, -ret,
                              "Failed to flush the refcount block cache");
             goto fail;
         }
     }
 
     r->l2_slice_size = l2_cache_entry_size / l2_entry_size(s);
     r->l2_table_cache = qcow2_cache_create(bs, l2_cache_size,
                                            l2_cache_entry_size);
     r->refcount_block_cache = qcow2_cache_create(bs, refcount_cache_size,
                                                  s->cluster_size);
     if (r->l2_table_cache == NULL || r->refcount_block_cache == NULL) {
         error_setg(errp, "Could not allocate metadata caches");
         ret = -ENOMEM;
         goto fail;
     }
 
     /* New interval for cache cleanup timer */
     r->cache_clean_interval =
         qemu_opt_get_number(opts, QCOW2_OPT_CACHE_CLEAN_INTERVAL,
                             DEFAULT_CACHE_CLEAN_INTERVAL);
 #ifndef CONFIG_LINUX
     if (r->cache_clean_interval != 0) {
         error_setg(errp, QCOW2_OPT_CACHE_CLEAN_INTERVAL
                    " not supported on this host");
         ret = -EINVAL;
         goto fail;
     }
 #endif
     if (r->cache_clean_interval > UINT_MAX) {
         error_setg(errp, "Cache clean interval too big");
         ret = -EINVAL;
         goto fail;
     }
 
     /* lazy-refcounts; flush if going from enabled to disabled */
     r->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS,
         (s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS));
     if (r->use_lazy_refcounts && s->qcow_version < 3) {
         error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
                    "qemu 1.1 compatibility level");
         ret = -EINVAL;
         goto fail;
     }
 
     if (s->use_lazy_refcounts && !r->use_lazy_refcounts) {
         ret = qcow2_mark_clean(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to disable lazy refcounts");
             goto fail;
         }
     }
 
     /* Overlap check options */
     opt_overlap_check = qemu_opt_get(opts, QCOW2_OPT_OVERLAP);
     opt_overlap_check_template = qemu_opt_get(opts, QCOW2_OPT_OVERLAP_TEMPLATE);
     if (opt_overlap_check_template && opt_overlap_check &&
         strcmp(opt_overlap_check_template, opt_overlap_check))
     {
         error_setg(errp, "Conflicting values for qcow2 options '"
                    QCOW2_OPT_OVERLAP "' ('%s') and '" QCOW2_OPT_OVERLAP_TEMPLATE
                    "' ('%s')", opt_overlap_check, opt_overlap_check_template);
         ret = -EINVAL;
         goto fail;
     }
     if (!opt_overlap_check) {
         opt_overlap_check = opt_overlap_check_template ?: "cached";
     }
 
     if (!strcmp(opt_overlap_check, "none")) {
         overlap_check_template = 0;
     } else if (!strcmp(opt_overlap_check, "constant")) {
         overlap_check_template = QCOW2_OL_CONSTANT;
     } else if (!strcmp(opt_overlap_check, "cached")) {
         overlap_check_template = QCOW2_OL_CACHED;
     } else if (!strcmp(opt_overlap_check, "all")) {
         overlap_check_template = QCOW2_OL_ALL;
     } else {
         error_setg(errp, "Unsupported value '%s' for qcow2 option "
                    "'overlap-check'. Allowed are any of the following: "
                    "none, constant, cached, all", opt_overlap_check);
         ret = -EINVAL;
         goto fail;
     }
 
     r->overlap_check = 0;
     for (i = 0; i < QCOW2_OL_MAX_BITNR; i++) {
         /* overlap-check defines a template bitmask, but every flag may be
          * overwritten through the associated boolean option */
         r->overlap_check |=
             qemu_opt_get_bool(opts, overlap_bool_option_names[i],
                               overlap_check_template & (1 << i)) << i;
     }
 
     r->discard_passthrough[QCOW2_DISCARD_NEVER] = false;
     r->discard_passthrough[QCOW2_DISCARD_ALWAYS] = true;
     r->discard_passthrough[QCOW2_DISCARD_REQUEST] =
         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_REQUEST,
                           flags & BDRV_O_UNMAP);
     r->discard_passthrough[QCOW2_DISCARD_SNAPSHOT] =
         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SNAPSHOT, true);
     r->discard_passthrough[QCOW2_DISCARD_OTHER] =
         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false);
 
     switch (s->crypt_method_header) {
     case QCOW_CRYPT_NONE:
         if (encryptfmt) {
             error_setg(errp, "No encryption in image header, but options "
                        "specified format '%s'", encryptfmt);
             ret = -EINVAL;
             goto fail;
         }
         break;
 
     case QCOW_CRYPT_AES:
         if (encryptfmt && !g_str_equal(encryptfmt, "aes")) {
             error_setg(errp,
                        "Header reported 'aes' encryption format but "
                        "options specify '%s'", encryptfmt);
             ret = -EINVAL;
             goto fail;
         }
         qdict_put_str(encryptopts, "format", "qcow");
         r->crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
         if (!r->crypto_opts) {
             ret = -EINVAL;
             goto fail;
         }
         break;
 
     case QCOW_CRYPT_LUKS:
         if (encryptfmt && !g_str_equal(encryptfmt, "luks")) {
             error_setg(errp,
                        "Header reported 'luks' encryption format but "
                        "options specify '%s'", encryptfmt);
             ret = -EINVAL;
             goto fail;
         }
         qdict_put_str(encryptopts, "format", "luks");
         r->crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
         if (!r->crypto_opts) {
             ret = -EINVAL;
             goto fail;
         }
         break;
 
     default:
         error_setg(errp, "Unsupported encryption method %d",
                    s->crypt_method_header);
         ret = -EINVAL;
         goto fail;
     }
 
     ret = 0;
 fail:
     qobject_unref(encryptopts);
     qemu_opts_del(opts);
     opts = NULL;
     return ret;
 }
 
 static void qcow2_update_options_commit(BlockDriverState *bs,
                                         Qcow2ReopenState *r)
 {
     BDRVQcow2State *s = bs->opaque;
     int i;
 
     if (s->l2_table_cache) {
         qcow2_cache_destroy(s->l2_table_cache);
     }
     if (s->refcount_block_cache) {
         qcow2_cache_destroy(s->refcount_block_cache);
     }
     s->l2_table_cache = r->l2_table_cache;
     s->refcount_block_cache = r->refcount_block_cache;
     s->l2_slice_size = r->l2_slice_size;
 
     s->overlap_check = r->overlap_check;
     s->use_lazy_refcounts = r->use_lazy_refcounts;
 
     for (i = 0; i < QCOW2_DISCARD_MAX; i++) {
         s->discard_passthrough[i] = r->discard_passthrough[i];
     }
 
     if (s->cache_clean_interval != r->cache_clean_interval) {
         cache_clean_timer_del(bs);
         s->cache_clean_interval = r->cache_clean_interval;
         cache_clean_timer_init(bs, bdrv_get_aio_context(bs));
     }
 
     qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
     s->crypto_opts = r->crypto_opts;
 }
 
 static void qcow2_update_options_abort(BlockDriverState *bs,
                                        Qcow2ReopenState *r)
 {
     if (r->l2_table_cache) {
         qcow2_cache_destroy(r->l2_table_cache);
     }
     if (r->refcount_block_cache) {
         qcow2_cache_destroy(r->refcount_block_cache);
     }
     qapi_free_QCryptoBlockOpenOptions(r->crypto_opts);
 }
 
 static int qcow2_update_options(BlockDriverState *bs, QDict *options,
                                 int flags, Error **errp)
 {
     Qcow2ReopenState r = {};
     int ret;
 
     ret = qcow2_update_options_prepare(bs, &r, options, flags, errp);
     if (ret >= 0) {
         qcow2_update_options_commit(bs, &r);
     } else {
         qcow2_update_options_abort(bs, &r);
     }
 
     return ret;
 }
 
 static int validate_compression_type(BDRVQcow2State *s, Error **errp)
 {
     switch (s->compression_type) {
     case QCOW2_COMPRESSION_TYPE_ZLIB:
 #ifdef CONFIG_ZSTD
     case QCOW2_COMPRESSION_TYPE_ZSTD:
 #endif
         break;
 
     default:
         error_setg(errp, "qcow2: unknown compression type: %u",
                    s->compression_type);
         return -ENOTSUP;
     }
 
     /*
      * if the compression type differs from QCOW2_COMPRESSION_TYPE_ZLIB
      * the incompatible feature flag must be set
      */
     if (s->compression_type == QCOW2_COMPRESSION_TYPE_ZLIB) {
         if (s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION) {
             error_setg(errp, "qcow2: Compression type incompatible feature "
                              "bit must not be set");
             return -EINVAL;
         }
     } else {
         if (!(s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION)) {
             error_setg(errp, "qcow2: Compression type incompatible feature "
                              "bit must be set");
             return -EINVAL;
         }
     }
 
     return 0;
 }
 
 /* Called with s->lock held.  */
 static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
                                       int flags, bool open_data_file,
                                       Error **errp)
 {
     ERRP_GUARD();
     BDRVQcow2State *s = bs->opaque;
     unsigned int len, i;
     int ret = 0;
     QCowHeader header;
     uint64_t ext_end;
     uint64_t l1_vm_state_index;
     bool update_header = false;
 
     ret = bdrv_co_pread(bs->file, 0, sizeof(header), &header, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not read qcow2 header");
         goto fail;
     }
     header.magic = be32_to_cpu(header.magic);
     header.version = be32_to_cpu(header.version);
     header.backing_file_offset = be64_to_cpu(header.backing_file_offset);
     header.backing_file_size = be32_to_cpu(header.backing_file_size);
     header.size = be64_to_cpu(header.size);
     header.cluster_bits = be32_to_cpu(header.cluster_bits);
     header.crypt_method = be32_to_cpu(header.crypt_method);
     header.l1_table_offset = be64_to_cpu(header.l1_table_offset);
     header.l1_size = be32_to_cpu(header.l1_size);
     header.refcount_table_offset = be64_to_cpu(header.refcount_table_offset);
     header.refcount_table_clusters =
         be32_to_cpu(header.refcount_table_clusters);
     header.snapshots_offset = be64_to_cpu(header.snapshots_offset);
     header.nb_snapshots = be32_to_cpu(header.nb_snapshots);
 
     if (header.magic != QCOW_MAGIC) {
         error_setg(errp, "Image is not in qcow2 format");
         ret = -EINVAL;
         goto fail;
     }
     if (header.version < 2 || header.version > 3) {
         error_setg(errp, "Unsupported qcow2 version %" PRIu32, header.version);
         ret = -ENOTSUP;
         goto fail;
     }
 
     s->qcow_version = header.version;
 
     /* Initialise cluster size */
     if (header.cluster_bits < MIN_CLUSTER_BITS ||
         header.cluster_bits > MAX_CLUSTER_BITS) {
         error_setg(errp, "Unsupported cluster size: 2^%" PRIu32,
                    header.cluster_bits);
         ret = -EINVAL;
         goto fail;
     }
 
     s->cluster_bits = header.cluster_bits;
     s->cluster_size = 1 << s->cluster_bits;
 
     /* Initialise version 3 header fields */
     if (header.version == 2) {
         header.incompatible_features    = 0;
         header.compatible_features      = 0;
         header.autoclear_features       = 0;
         header.refcount_order           = 4;
         header.header_length            = 72;
     } else {
         header.incompatible_features =
             be64_to_cpu(header.incompatible_features);
         header.compatible_features = be64_to_cpu(header.compatible_features);
         header.autoclear_features = be64_to_cpu(header.autoclear_features);
         header.refcount_order = be32_to_cpu(header.refcount_order);
         header.header_length = be32_to_cpu(header.header_length);
 
         if (header.header_length < 104) {
             error_setg(errp, "qcow2 header too short");
             ret = -EINVAL;
             goto fail;
         }
     }
 
     if (header.header_length > s->cluster_size) {
         error_setg(errp, "qcow2 header exceeds cluster size");
         ret = -EINVAL;
         goto fail;
     }
 
     if (header.header_length > sizeof(header)) {
         s->unknown_header_fields_size = header.header_length - sizeof(header);
         s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
         ret = bdrv_co_pread(bs->file, sizeof(header),
                             s->unknown_header_fields_size,
                             s->unknown_header_fields, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not read unknown qcow2 header "
                              "fields");
             goto fail;
         }
     }
 
     if (header.backing_file_offset > s->cluster_size) {
         error_setg(errp, "Invalid backing file offset");
         ret = -EINVAL;
         goto fail;
     }
 
     if (header.backing_file_offset) {
         ext_end = header.backing_file_offset;
     } else {
         ext_end = 1 << header.cluster_bits;
     }
 
     /* Handle feature bits */
     s->incompatible_features    = header.incompatible_features;
     s->compatible_features      = header.compatible_features;
     s->autoclear_features       = header.autoclear_features;
 
     /*
      * Handle compression type
      * Older qcow2 images don't contain the compression type header.
      * Distinguish them by the header length and use
      * the only valid (default) compression type in that case
      */
     if (header.header_length > offsetof(QCowHeader, compression_type)) {
         s->compression_type = header.compression_type;
     } else {
         s->compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
     }
 
     ret = validate_compression_type(s, errp);
     if (ret) {
         goto fail;
     }
 
     if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) {
         void *feature_table = NULL;
         qcow2_read_extensions(bs, header.header_length, ext_end,
                               &feature_table, flags, NULL, NULL);
         report_unsupported_feature(errp, feature_table,
                                    s->incompatible_features &
                                    ~QCOW2_INCOMPAT_MASK);
         ret = -ENOTSUP;
         g_free(feature_table);
         goto fail;
     }
 
     if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
         /* Corrupt images may not be written to unless they are being repaired
          */
         if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
             error_setg(errp, "qcow2: Image is corrupt; cannot be opened "
                        "read/write");
             ret = -EACCES;
             goto fail;
         }
     }
 
     s->subclusters_per_cluster =
         has_subclusters(s) ? QCOW_EXTL2_SUBCLUSTERS_PER_CLUSTER : 1;
     s->subcluster_size = s->cluster_size / s->subclusters_per_cluster;
     s->subcluster_bits = ctz32(s->subcluster_size);
 
     if (s->subcluster_size < (1 << MIN_CLUSTER_BITS)) {
         error_setg(errp, "Unsupported subcluster size: %d", s->subcluster_size);
         ret = -EINVAL;
         goto fail;
     }
 
     /* Check support for various header values */
     if (header.refcount_order > 6) {
         error_setg(errp, "Reference count entry width too large; may not "
                    "exceed 64 bits");
         ret = -EINVAL;
         goto fail;
     }
     s->refcount_order = header.refcount_order;
     s->refcount_bits = 1 << s->refcount_order;
     s->refcount_max = UINT64_C(1) << (s->refcount_bits - 1);
     s->refcount_max += s->refcount_max - 1;
 
     s->crypt_method_header = header.crypt_method;
     if (s->crypt_method_header) {
         if (bdrv_uses_whitelist() &&
             s->crypt_method_header == QCOW_CRYPT_AES) {
             error_setg(errp,
                        "Use of AES-CBC encrypted qcow2 images is no longer "
                        "supported in system emulators");
             error_append_hint(errp,
                               "You can use 'qemu-img convert' to convert your "
                               "image to an alternative supported format, such "
                               "as unencrypted qcow2, or raw with the LUKS "
                               "format instead.\n");
             ret = -ENOSYS;
             goto fail;
         }
 
         if (s->crypt_method_header == QCOW_CRYPT_AES) {
             s->crypt_physical_offset = false;
         } else {
             /* Assuming LUKS and any future crypt methods we
              * add will all use physical offsets, due to the
              * fact that the alternative is insecure...  */
             s->crypt_physical_offset = true;
         }
 
         bs->encrypted = true;
     }
 
     s->l2_bits = s->cluster_bits - ctz32(l2_entry_size(s));
     s->l2_size = 1 << s->l2_bits;
     /* 2^(s->refcount_order - 3) is the refcount width in bytes */
     s->refcount_block_bits = s->cluster_bits - (s->refcount_order - 3);
     s->refcount_block_size = 1 << s->refcount_block_bits;
     bs->total_sectors = header.size / BDRV_SECTOR_SIZE;
     s->csize_shift = (62 - (s->cluster_bits - 8));
     s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
     s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
 
     s->refcount_table_offset = header.refcount_table_offset;
     s->refcount_table_size =
         header.refcount_table_clusters << (s->cluster_bits - 3);
 
     if (header.refcount_table_clusters == 0 && !(flags & BDRV_O_CHECK)) {
         error_setg(errp, "Image does not contain a reference count table");
         ret = -EINVAL;
         goto fail;
     }
 
     ret = qcow2_validate_table(bs, s->refcount_table_offset,
                                header.refcount_table_clusters,
                                s->cluster_size, QCOW_MAX_REFTABLE_SIZE,
                                "Reference count table", errp);
     if (ret < 0) {
         goto fail;
     }
 
     if (!(flags & BDRV_O_CHECK)) {
         /*
          * The total size in bytes of the snapshot table is checked in
          * qcow2_read_snapshots() because the size of each snapshot is
          * variable and we don't know it yet.
          * Here we only check the offset and number of snapshots.
          */
         ret = qcow2_validate_table(bs, header.snapshots_offset,
                                    header.nb_snapshots,
                                    sizeof(QCowSnapshotHeader),
                                    sizeof(QCowSnapshotHeader) *
                                        QCOW_MAX_SNAPSHOTS,
                                    "Snapshot table", errp);
         if (ret < 0) {
             goto fail;
         }
     }
 
     /* read the level 1 table */
     ret = qcow2_validate_table(bs, header.l1_table_offset,
                                header.l1_size, L1E_SIZE,
                                QCOW_MAX_L1_SIZE, "Active L1 table", errp);
     if (ret < 0) {
         goto fail;
     }
     s->l1_size = header.l1_size;
     s->l1_table_offset = header.l1_table_offset;
 
     l1_vm_state_index = size_to_l1(s, header.size);
     if (l1_vm_state_index > INT_MAX) {
         error_setg(errp, "Image is too big");
         ret = -EFBIG;
         goto fail;
     }
     s->l1_vm_state_index = l1_vm_state_index;
 
     /* the L1 table must contain at least enough entries to put
        header.size bytes */
     if (s->l1_size < s->l1_vm_state_index) {
         error_setg(errp, "L1 table is too small");
         ret = -EINVAL;
         goto fail;
     }
 
     if (s->l1_size > 0) {
         s->l1_table = qemu_try_blockalign(bs->file->bs, s->l1_size * L1E_SIZE);
         if (s->l1_table == NULL) {
             error_setg(errp, "Could not allocate L1 table");
             ret = -ENOMEM;
             goto fail;
         }
         ret = bdrv_co_pread(bs->file, s->l1_table_offset, s->l1_size * L1E_SIZE,
                             s->l1_table, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not read L1 table");
             goto fail;
         }
         for(i = 0;i < s->l1_size; i++) {
             s->l1_table[i] = be64_to_cpu(s->l1_table[i]);
         }
     }
 
     /* Parse driver-specific options */
     ret = qcow2_update_options(bs, options, flags, errp);
     if (ret < 0) {
         goto fail;
     }
 
     s->flags = flags;
 
     ret = qcow2_refcount_init(bs);
     if (ret != 0) {
         error_setg_errno(errp, -ret, "Could not initialize refcount handling");
         goto fail;
     }
 
     QLIST_INIT(&s->cluster_allocs);
     QTAILQ_INIT(&s->discards);
 
     /* read qcow2 extensions */
     if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL,
                               flags, &update_header, errp)) {
         ret = -EINVAL;
         goto fail;
     }
 
     if (open_data_file) {
         /* Open external data file */
         s->data_file = bdrv_open_child(NULL, options, "data-file", bs,
                                        &child_of_bds, BDRV_CHILD_DATA,
                                        true, errp);
         if (*errp) {
             ret = -EINVAL;
             goto fail;
         }
 
         if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
             if (!s->data_file && s->image_data_file) {
                 s->data_file = bdrv_open_child(s->image_data_file, options,
                                                "data-file", bs, &child_of_bds,
                                                BDRV_CHILD_DATA, false, errp);
                 if (!s->data_file) {
                     ret = -EINVAL;
                     goto fail;
                 }
             }
             if (!s->data_file) {
                 error_setg(errp, "'data-file' is required for this image");
                 ret = -EINVAL;
                 goto fail;
             }
 
             /* No data here */
             bs->file->role &= ~BDRV_CHILD_DATA;
 
             /* Must succeed because we have given up permissions if anything */
             bdrv_child_refresh_perms(bs, bs->file, &error_abort);
         } else {
             if (s->data_file) {
                 error_setg(errp, "'data-file' can only be set for images with "
                                  "an external data file");
                 ret = -EINVAL;
                 goto fail;
             }
 
             s->data_file = bs->file;
 
             if (data_file_is_raw(bs)) {
                 error_setg(errp, "data-file-raw requires a data file");
                 ret = -EINVAL;
                 goto fail;
             }
         }
     }
 
     /* qcow2_read_extension may have set up the crypto context
      * if the crypt method needs a header region, some methods
      * don't need header extensions, so must check here
      */
     if (s->crypt_method_header && !s->crypto) {
         if (s->crypt_method_header == QCOW_CRYPT_AES) {
             unsigned int cflags = 0;
             if (flags & BDRV_O_NO_IO) {
                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
             }
             s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
                                            NULL, NULL, cflags,
                                            QCOW2_MAX_THREADS, errp);
             if (!s->crypto) {
                 ret = -EINVAL;
                 goto fail;
             }
         } else if (!(flags & BDRV_O_NO_IO)) {
             error_setg(errp, "Missing CRYPTO header for crypt method %d",
                        s->crypt_method_header);
             ret = -EINVAL;
             goto fail;
         }
     }
 
     /* read the backing file name */
     if (header.backing_file_offset != 0) {
         len = header.backing_file_size;
         if (len > MIN(1023, s->cluster_size - header.backing_file_offset) ||
             len >= sizeof(bs->backing_file)) {
             error_setg(errp, "Backing file name too long");
             ret = -EINVAL;
             goto fail;
         }
 
         s->image_backing_file = g_malloc(len + 1);
         ret = bdrv_co_pread(bs->file, header.backing_file_offset, len,
                             s->image_backing_file, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not read backing file name");
             goto fail;
         }
         s->image_backing_file[len] = '\0';
 
         /*
          * Update only when something has changed.  This function is called by
          * qcow2_co_invalidate_cache(), and we do not want to reset
          * auto_backing_file unless necessary.
          */
         if (!g_str_equal(s->image_backing_file, bs->backing_file)) {
             pstrcpy(bs->backing_file, sizeof(bs->backing_file),
                     s->image_backing_file);
             pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
                     s->image_backing_file);
         }
     }
 
     /*
      * Internal snapshots; skip reading them in check mode, because
      * we do not need them then, and we do not want to abort because
      * of a broken table.
      */
     if (!(flags & BDRV_O_CHECK)) {
         s->snapshots_offset = header.snapshots_offset;
         s->nb_snapshots = header.nb_snapshots;
 
         ret = qcow2_read_snapshots(bs, errp);
         if (ret < 0) {
             goto fail;
         }
     }
 
     /* Clear unknown autoclear feature bits */
     update_header |= s->autoclear_features & ~QCOW2_AUTOCLEAR_MASK;
     update_header = update_header && bdrv_is_writable(bs);
     if (update_header) {
         s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
     }
 
     /* == Handle persistent dirty bitmaps ==
      *
      * We want load dirty bitmaps in three cases:
      *
      * 1. Normal open of the disk in active mode, not related to invalidation
      *    after migration.
      *
      * 2. Invalidation of the target vm after pre-copy phase of migration, if
      *    bitmaps are _not_ migrating through migration channel, i.e.
      *    'dirty-bitmaps' capability is disabled.
      *
      * 3. Invalidation of source vm after failed or canceled migration.
      *    This is a very interesting case. There are two possible types of
      *    bitmaps:
      *
      *    A. Stored on inactivation and removed. They should be loaded from the
      *       image.
      *
      *    B. Not stored: not-persistent bitmaps and bitmaps, migrated through
      *       the migration channel (with dirty-bitmaps capability).
      *
      *    On the other hand, there are two possible sub-cases:
      *
      *    3.1 disk was changed by somebody else while were inactive. In this
      *        case all in-RAM dirty bitmaps (both persistent and not) are
      *        definitely invalid. And we don't have any method to determine
      *        this.
      *
      *        Simple and safe thing is to just drop all the bitmaps of type B on
      *        inactivation. But in this case we lose bitmaps in valid 4.2 case.
      *
      *        On the other hand, resuming source vm, if disk was already changed
      *        is a bad thing anyway: not only bitmaps, the whole vm state is
      *        out of sync with disk.
      *
      *        This means, that user or management tool, who for some reason
      *        decided to resume source vm, after disk was already changed by
      *        target vm, should at least drop all dirty bitmaps by hand.
      *
      *        So, we can ignore this case for now, but TODO: "generation"
      *        extension for qcow2, to determine, that image was changed after
      *        last inactivation. And if it is changed, we will drop (or at least
      *        mark as 'invalid' all the bitmaps of type B, both persistent
      *        and not).
      *
      *    3.2 disk was _not_ changed while were inactive. Bitmaps may be saved
      *        to disk ('dirty-bitmaps' capability disabled), or not saved
      *        ('dirty-bitmaps' capability enabled), but we don't need to care
      *        of: let's load bitmaps as always: stored bitmaps will be loaded,
      *        and not stored has flag IN_USE=1 in the image and will be skipped
      *        on loading.
      *
      * One remaining possible case when we don't want load bitmaps:
      *
      * 4. Open disk in inactive mode in target vm (bitmaps are migrating or
      *    will be loaded on invalidation, no needs try loading them before)
      */
 
     if (!(bdrv_get_flags(bs) & BDRV_O_INACTIVE)) {
         /* It's case 1, 2 or 3.2. Or 3.1 which is BUG in management layer. */
         bool header_updated;
         if (!qcow2_load_dirty_bitmaps(bs, &header_updated, errp)) {
             ret = -EINVAL;
             goto fail;
         }
 
         update_header = update_header && !header_updated;
     }
 
     if (update_header) {
         ret = qcow2_update_header(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not update qcow2 header");
             goto fail;
         }
     }
 
     bs->supported_zero_flags = header.version >= 3 ?
                                BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK : 0;
     bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
 
     /* Repair image if dirty */
     if (!(flags & BDRV_O_CHECK) && bdrv_is_writable(bs) &&
         (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) {
         BdrvCheckResult result = {0};
 
         ret = qcow2_co_check_locked(bs, &result,
                                     BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
         if (ret < 0 || result.check_errors) {
             if (ret >= 0) {
                 ret = -EIO;
             }
             error_setg_errno(errp, -ret, "Could not repair dirty image");
             goto fail;
         }
     }
 
 #ifdef DEBUG_ALLOC
     {
         BdrvCheckResult result = {0};
         qcow2_check_refcounts(bs, &result, 0);
     }
 #endif
 
     qemu_co_queue_init(&s->thread_task_queue);
 
     return ret;
 
  fail:
     g_free(s->image_data_file);
     if (open_data_file && has_data_file(bs)) {
         bdrv_unref_child(bs, s->data_file);
         s->data_file = NULL;
     }
     g_free(s->unknown_header_fields);
     cleanup_unknown_header_ext(bs);
     qcow2_free_snapshots(bs);
     qcow2_refcount_close(bs);
     qemu_vfree(s->l1_table);
     /* else pre-write overlap checks in cache_destroy may crash */
     s->l1_table = NULL;
     cache_clean_timer_del(bs);
     if (s->l2_table_cache) {
         qcow2_cache_destroy(s->l2_table_cache);
     }
     if (s->refcount_block_cache) {
         qcow2_cache_destroy(s->refcount_block_cache);
     }
     qcrypto_block_free(s->crypto);
     qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
     return ret;
 }
 
 typedef struct QCow2OpenCo {
     BlockDriverState *bs;
     QDict *options;
     int flags;
     Error **errp;
     int ret;
 } QCow2OpenCo;
 
 static void coroutine_fn qcow2_open_entry(void *opaque)
 {
     QCow2OpenCo *qoc = opaque;
     BDRVQcow2State *s = qoc->bs->opaque;
 
     qemu_co_mutex_lock(&s->lock);
     qoc->ret = qcow2_do_open(qoc->bs, qoc->options, qoc->flags, true,
                              qoc->errp);
     qemu_co_mutex_unlock(&s->lock);
 }
 
 static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
                       Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     QCow2OpenCo qoc = {
         .bs = bs,
         .options = options,
         .flags = flags,
         .errp = errp,
         .ret = -EINPROGRESS
     };
     int ret;
 
     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
     if (ret < 0) {
         return ret;
     }
 
     /* Initialise locks */
     qemu_co_mutex_init(&s->lock);
 
     if (qemu_in_coroutine()) {
         /* From bdrv_co_create.  */
         qcow2_open_entry(&qoc);
     } else {
         assert(qemu_get_current_aio_context() == qemu_get_aio_context());
         qemu_coroutine_enter(qemu_coroutine_create(qcow2_open_entry, &qoc));
         BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS);
     }
     return qoc.ret;
 }
 
 static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
 
     if (bs->encrypted) {
         /* Encryption works on a sector granularity */
         bs->bl.request_alignment = qcrypto_block_get_sector_size(s->crypto);
     }
     bs->bl.pwrite_zeroes_alignment = s->subcluster_size;
     bs->bl.pdiscard_alignment = s->cluster_size;
 }
 
 static int qcow2_reopen_prepare(BDRVReopenState *state,
                                 BlockReopenQueue *queue, Error **errp)
 {
     BDRVQcow2State *s = state->bs->opaque;
     Qcow2ReopenState *r;
     int ret;
 
     r = g_new0(Qcow2ReopenState, 1);
     state->opaque = r;
 
     ret = qcow2_update_options_prepare(state->bs, r, state->options,
                                        state->flags, errp);
     if (ret < 0) {
         goto fail;
     }
 
     /* We need to write out any unwritten data if we reopen read-only. */
     if ((state->flags & BDRV_O_RDWR) == 0) {
         ret = qcow2_reopen_bitmaps_ro(state->bs, errp);
         if (ret < 0) {
             goto fail;
         }
 
         ret = bdrv_flush(state->bs);
         if (ret < 0) {
             goto fail;
         }
 
         ret = qcow2_mark_clean(state->bs);
         if (ret < 0) {
             goto fail;
         }
     }
 
     /*
      * Without an external data file, s->data_file points to the same BdrvChild
      * as bs->file. It needs to be resynced after reopen because bs->file may
      * be changed. We can't use it in the meantime.
      */
     if (!has_data_file(state->bs)) {
         assert(s->data_file == state->bs->file);
         s->data_file = NULL;
     }
 
     return 0;
 
 fail:
     qcow2_update_options_abort(state->bs, r);
     g_free(r);
     return ret;
 }
 
 static void qcow2_reopen_commit(BDRVReopenState *state)
 {
     BDRVQcow2State *s = state->bs->opaque;
 
     qcow2_update_options_commit(state->bs, state->opaque);
     if (!s->data_file) {
         /*
          * If we don't have an external data file, s->data_file was cleared by
          * qcow2_reopen_prepare() and needs to be updated.
          */
         s->data_file = state->bs->file;
     }
     g_free(state->opaque);
 }
 
 static void qcow2_reopen_commit_post(BDRVReopenState *state)
 {
     if (state->flags & BDRV_O_RDWR) {
         Error *local_err = NULL;
 
         if (qcow2_reopen_bitmaps_rw(state->bs, &local_err) < 0) {
             /*
              * This is not fatal, bitmaps just left read-only, so all following
              * writes will fail. User can remove read-only bitmaps to unblock
              * writes or retry reopen.
              */
             error_reportf_err(local_err,
                               "%s: Failed to make dirty bitmaps writable: ",
                               bdrv_get_node_name(state->bs));
         }
     }
 }
 
 static void qcow2_reopen_abort(BDRVReopenState *state)
 {
     BDRVQcow2State *s = state->bs->opaque;
 
     if (!s->data_file) {
         /*
          * If we don't have an external data file, s->data_file was cleared by
          * qcow2_reopen_prepare() and needs to be restored.
          */
         s->data_file = state->bs->file;
     }
     qcow2_update_options_abort(state->bs, state->opaque);
     g_free(state->opaque);
 }
 
 static void qcow2_join_options(QDict *options, QDict *old_options)
 {
     bool has_new_overlap_template =
         qdict_haskey(options, QCOW2_OPT_OVERLAP) ||
         qdict_haskey(options, QCOW2_OPT_OVERLAP_TEMPLATE);
     bool has_new_total_cache_size =
         qdict_haskey(options, QCOW2_OPT_CACHE_SIZE);
     bool has_all_cache_options;
 
     /* New overlap template overrides all old overlap options */
     if (has_new_overlap_template) {
         qdict_del(old_options, QCOW2_OPT_OVERLAP);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_TEMPLATE);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_MAIN_HEADER);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_ACTIVE_L1);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_ACTIVE_L2);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_REFCOUNT_TABLE);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_INACTIVE_L1);
         qdict_del(old_options, QCOW2_OPT_OVERLAP_INACTIVE_L2);
     }
 
     /* New total cache size overrides all old options */
     if (qdict_haskey(options, QCOW2_OPT_CACHE_SIZE)) {
         qdict_del(old_options, QCOW2_OPT_L2_CACHE_SIZE);
         qdict_del(old_options, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
     }
 
     qdict_join(options, old_options, false);
 
     /*
      * If after merging all cache size options are set, an old total size is
      * overwritten. Do keep all options, however, if all three are new. The
      * resulting error message is what we want to happen.
      */
     has_all_cache_options =
         qdict_haskey(options, QCOW2_OPT_CACHE_SIZE) ||
         qdict_haskey(options, QCOW2_OPT_L2_CACHE_SIZE) ||
         qdict_haskey(options, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
 
     if (has_all_cache_options && !has_new_total_cache_size) {
         qdict_del(options, QCOW2_OPT_CACHE_SIZE);
     }
 }
 
 static int coroutine_fn qcow2_co_block_status(BlockDriverState *bs,
                                               bool want_zero,
                                               int64_t offset, int64_t count,
                                               int64_t *pnum, int64_t *map,
                                               BlockDriverState **file)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t host_offset;
     unsigned int bytes;
     QCow2SubclusterType type;
     int ret, status = 0;
 
     qemu_co_mutex_lock(&s->lock);
 
     if (!s->metadata_preallocation_checked) {
         ret = qcow2_detect_metadata_preallocation(bs);
         s->metadata_preallocation = (ret == 1);
         s->metadata_preallocation_checked = true;
     }
 
     bytes = MIN(INT_MAX, count);
     ret = qcow2_get_host_offset(bs, offset, &bytes, &host_offset, &type);
     qemu_co_mutex_unlock(&s->lock);
     if (ret < 0) {
         return ret;
     }
 
     *pnum = bytes;
 
     if ((type == QCOW2_SUBCLUSTER_NORMAL ||
          type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
          type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC) && !s->crypto) {
         *map = host_offset;
         *file = s->data_file->bs;
         status |= BDRV_BLOCK_OFFSET_VALID;
     }
     if (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
         type == QCOW2_SUBCLUSTER_ZERO_ALLOC) {
         status |= BDRV_BLOCK_ZERO;
     } else if (type != QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN &&
                type != QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC) {
         status |= BDRV_BLOCK_DATA;
     }
     if (s->metadata_preallocation && (status & BDRV_BLOCK_DATA) &&
         (status & BDRV_BLOCK_OFFSET_VALID))
     {
         status |= BDRV_BLOCK_RECURSE;
     }
     return status;
 }
 
 static coroutine_fn int qcow2_handle_l2meta(BlockDriverState *bs,
                                             QCowL2Meta **pl2meta,
                                             bool link_l2)
 {
     int ret = 0;
     QCowL2Meta *l2meta = *pl2meta;
 
     while (l2meta != NULL) {
         QCowL2Meta *next;
 
         if (link_l2) {
             ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
             if (ret) {
                 goto out;
             }
         } else {
             qcow2_alloc_cluster_abort(bs, l2meta);
         }
 
         /* Take the request off the list of running requests */
         QLIST_REMOVE(l2meta, next_in_flight);
 
         qemu_co_queue_restart_all(&l2meta->dependent_requests);
 
         next = l2meta->next;
         g_free(l2meta);
         l2meta = next;
     }
 out:
     *pl2meta = l2meta;
     return ret;
 }
 
 static coroutine_fn int
 qcow2_co_preadv_encrypted(BlockDriverState *bs,
                            uint64_t host_offset,
                            uint64_t offset,
                            uint64_t bytes,
                            QEMUIOVector *qiov,
                            uint64_t qiov_offset)
 {
     int ret;
     BDRVQcow2State *s = bs->opaque;
     uint8_t *buf;
 
     assert(bs->encrypted && s->crypto);
     assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
 
     /*
      * For encrypted images, read everything into a temporary
      * contiguous buffer on which the AES functions can work.
      * Also, decryption in a separate buffer is better as it
      * prevents the guest from learning information about the
      * encrypted nature of the virtual disk.
      */
 
     buf = qemu_try_blockalign(s->data_file->bs, bytes);
     if (buf == NULL) {
         return -ENOMEM;
     }
 
     BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
     ret = bdrv_co_pread(s->data_file, host_offset, bytes, buf, 0);
     if (ret < 0) {
         goto fail;
     }
 
     if (qcow2_co_decrypt(bs, host_offset, offset, buf, bytes) < 0)
     {
         ret = -EIO;
         goto fail;
     }
     qemu_iovec_from_buf(qiov, qiov_offset, buf, bytes);
 
 fail:
     qemu_vfree(buf);
 
     return ret;
 }
 
 typedef struct Qcow2AioTask {
     AioTask task;
 
     BlockDriverState *bs;
     QCow2SubclusterType subcluster_type; /* only for read */
     uint64_t host_offset; /* or l2_entry for compressed read */
     uint64_t offset;
     uint64_t bytes;
     QEMUIOVector *qiov;
     uint64_t qiov_offset;
     QCowL2Meta *l2meta; /* only for write */
 } Qcow2AioTask;
 
 static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task);
 static coroutine_fn int qcow2_add_task(BlockDriverState *bs,
                                        AioTaskPool *pool,
                                        AioTaskFunc func,
                                        QCow2SubclusterType subcluster_type,
                                        uint64_t host_offset,
                                        uint64_t offset,
                                        uint64_t bytes,
                                        QEMUIOVector *qiov,
                                        size_t qiov_offset,
                                        QCowL2Meta *l2meta)
 {
     Qcow2AioTask local_task;
     Qcow2AioTask *task = pool ? g_new(Qcow2AioTask, 1) : &local_task;
 
     *task = (Qcow2AioTask) {
         .task.func = func,
         .bs = bs,
         .subcluster_type = subcluster_type,
         .qiov = qiov,
         .host_offset = host_offset,
         .offset = offset,
         .bytes = bytes,
         .qiov_offset = qiov_offset,
         .l2meta = l2meta,
     };
 
     trace_qcow2_add_task(qemu_coroutine_self(), bs, pool,
                          func == qcow2_co_preadv_task_entry ? "read" : "write",
                          subcluster_type, host_offset, offset, bytes,
                          qiov, qiov_offset);
 
     if (!pool) {
         return func(&task->task);
     }
 
     aio_task_pool_start_task(pool, &task->task);
 
     return 0;
 }
 
 static coroutine_fn int qcow2_co_preadv_task(BlockDriverState *bs,
                                              QCow2SubclusterType subc_type,
                                              uint64_t host_offset,
                                              uint64_t offset, uint64_t bytes,
                                              QEMUIOVector *qiov,
                                              size_t qiov_offset)
 {
     BDRVQcow2State *s = bs->opaque;
 
     switch (subc_type) {
     case QCOW2_SUBCLUSTER_ZERO_PLAIN:
     case QCOW2_SUBCLUSTER_ZERO_ALLOC:
         /* Both zero types are handled in qcow2_co_preadv_part */
         g_assert_not_reached();
 
     case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
     case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
         assert(bs->backing); /* otherwise handled in qcow2_co_preadv_part */
 
         BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
         return bdrv_co_preadv_part(bs->backing, offset, bytes,
                                    qiov, qiov_offset, 0);
 
     case QCOW2_SUBCLUSTER_COMPRESSED:
         return qcow2_co_preadv_compressed(bs, host_offset,
                                           offset, bytes, qiov, qiov_offset);
 
     case QCOW2_SUBCLUSTER_NORMAL:
         if (bs->encrypted) {
             return qcow2_co_preadv_encrypted(bs, host_offset,
                                              offset, bytes, qiov, qiov_offset);
         }
 
         BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
         return bdrv_co_preadv_part(s->data_file, host_offset,
                                    bytes, qiov, qiov_offset, 0);
 
     default:
         g_assert_not_reached();
     }
 
     g_assert_not_reached();
 }
 
 static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task)
 {
     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
 
     assert(!t->l2meta);
 
     return qcow2_co_preadv_task(t->bs, t->subcluster_type,
                                 t->host_offset, t->offset, t->bytes,
                                 t->qiov, t->qiov_offset);
 }
 
 static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
                                              int64_t offset, int64_t bytes,
                                              QEMUIOVector *qiov,
                                              size_t qiov_offset,
                                              BdrvRequestFlags flags)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret = 0;
     unsigned int cur_bytes; /* number of bytes in current iteration */
     uint64_t host_offset = 0;
     QCow2SubclusterType type;
     AioTaskPool *aio = NULL;
 
     while (bytes != 0 && aio_task_pool_status(aio) == 0) {
         /* prepare next request */
         cur_bytes = MIN(bytes, INT_MAX);
         if (s->crypto) {
             cur_bytes = MIN(cur_bytes,
                             QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
         }
 
         qemu_co_mutex_lock(&s->lock);
         ret = qcow2_get_host_offset(bs, offset, &cur_bytes,
                                     &host_offset, &type);
         qemu_co_mutex_unlock(&s->lock);
         if (ret < 0) {
             goto out;
         }
 
         if (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
             type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
             (type == QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN && !bs->backing) ||
             (type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC && !bs->backing))
         {
             qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
         } else {
             if (!aio && cur_bytes != bytes) {
                 aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
             }
             ret = qcow2_add_task(bs, aio, qcow2_co_preadv_task_entry, type,
                                  host_offset, offset, cur_bytes,
                                  qiov, qiov_offset, NULL);
             if (ret < 0) {
                 goto out;
             }
         }
 
         bytes -= cur_bytes;
         offset += cur_bytes;
         qiov_offset += cur_bytes;
     }
 
 out:
     if (aio) {
         aio_task_pool_wait_all(aio);
         if (ret == 0) {
             ret = aio_task_pool_status(aio);
         }
         g_free(aio);
     }
 
     return ret;
 }
 
 /* Check if it's possible to merge a write request with the writing of
  * the data from the COW regions */
 static bool merge_cow(uint64_t offset, unsigned bytes,
                       QEMUIOVector *qiov, size_t qiov_offset,
                       QCowL2Meta *l2meta)
 {
     QCowL2Meta *m;
 
     for (m = l2meta; m != NULL; m = m->next) {
         /* If both COW regions are empty then there's nothing to merge */
         if (m->cow_start.nb_bytes == 0 && m->cow_end.nb_bytes == 0) {
             continue;
         }
 
         /* If COW regions are handled already, skip this too */
         if (m->skip_cow) {
             continue;
         }
 
         /*
          * The write request should start immediately after the first
          * COW region. This does not always happen because the area
          * touched by the request can be larger than the one defined
          * by @m (a single request can span an area consisting of a
          * mix of previously unallocated and allocated clusters, that
          * is why @l2meta is a list).
          */
         if (l2meta_cow_start(m) + m->cow_start.nb_bytes != offset) {
             /* In this case the request starts before this region */
             assert(offset < l2meta_cow_start(m));
             assert(m->cow_start.nb_bytes == 0);
             continue;
         }
 
         /* The write request should end immediately before the second
          * COW region (see above for why it does not always happen) */
         if (m->offset + m->cow_end.offset != offset + bytes) {
             assert(offset + bytes > m->offset + m->cow_end.offset);
             assert(m->cow_end.nb_bytes == 0);
             continue;
         }
 
         /* Make sure that adding both COW regions to the QEMUIOVector
          * does not exceed IOV_MAX */
         if (qemu_iovec_subvec_niov(qiov, qiov_offset, bytes) > IOV_MAX - 2) {
             continue;
         }
 
         m->data_qiov = qiov;
         m->data_qiov_offset = qiov_offset;
         return true;
     }
 
     return false;
 }
 
 /*
  * Return 1 if the COW regions read as zeroes, 0 if not, < 0 on error.
  * Note that returning 0 does not guarantee non-zero data.
  */
 static int coroutine_fn is_zero_cow(BlockDriverState *bs, QCowL2Meta *m)
 {
     /*
      * This check is designed for optimization shortcut so it must be
      * efficient.
      * Instead of is_zero(), use bdrv_co_is_zero_fast() as it is
      * faster (but not as accurate and can result in false negatives).
      */
     int ret = bdrv_co_is_zero_fast(bs, m->offset + m->cow_start.offset,
                                    m->cow_start.nb_bytes);
     if (ret <= 0) {
         return ret;
     }
 
     return bdrv_co_is_zero_fast(bs, m->offset + m->cow_end.offset,
                                 m->cow_end.nb_bytes);
 }
 
 static int coroutine_fn handle_alloc_space(BlockDriverState *bs,
                                            QCowL2Meta *l2meta)
 {
     BDRVQcow2State *s = bs->opaque;
     QCowL2Meta *m;
 
     if (!(s->data_file->bs->supported_zero_flags & BDRV_REQ_NO_FALLBACK)) {
         return 0;
     }
 
     if (bs->encrypted) {
         return 0;
     }
 
     for (m = l2meta; m != NULL; m = m->next) {
         int ret;
         uint64_t start_offset = m->alloc_offset + m->cow_start.offset;
         unsigned nb_bytes = m->cow_end.offset + m->cow_end.nb_bytes -
             m->cow_start.offset;
 
         if (!m->cow_start.nb_bytes && !m->cow_end.nb_bytes) {
             continue;
         }
 
         ret = is_zero_cow(bs, m);
         if (ret < 0) {
             return ret;
         } else if (ret == 0) {
             continue;
         }
 
         /*
          * instead of writing zero COW buffers,
          * efficiently zero out the whole clusters
          */
 
         ret = qcow2_pre_write_overlap_check(bs, 0, start_offset, nb_bytes,
                                             true);
         if (ret < 0) {
             return ret;
         }
 
         BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_SPACE);
         ret = bdrv_co_pwrite_zeroes(s->data_file, start_offset, nb_bytes,
                                     BDRV_REQ_NO_FALLBACK);
         if (ret < 0) {
             if (ret != -ENOTSUP && ret != -EAGAIN) {
                 return ret;
             }
             continue;
         }
 
         trace_qcow2_skip_cow(qemu_coroutine_self(), m->offset, m->nb_clusters);
         m->skip_cow = true;
     }
     return 0;
 }
 
 /*
  * qcow2_co_pwritev_task
  * Called with s->lock unlocked
  * l2meta  - if not NULL, qcow2_co_pwritev_task() will consume it. Caller must
  *           not use it somehow after qcow2_co_pwritev_task() call
  */
 static coroutine_fn int qcow2_co_pwritev_task(BlockDriverState *bs,
                                               uint64_t host_offset,
                                               uint64_t offset, uint64_t bytes,
                                               QEMUIOVector *qiov,
                                               uint64_t qiov_offset,
                                               QCowL2Meta *l2meta)
 {
     int ret;
     BDRVQcow2State *s = bs->opaque;
     void *crypt_buf = NULL;
     QEMUIOVector encrypted_qiov;
 
     if (bs->encrypted) {
         assert(s->crypto);
         assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
         crypt_buf = qemu_try_blockalign(bs->file->bs, bytes);
         if (crypt_buf == NULL) {
             ret = -ENOMEM;
             goto out_unlocked;
         }
         qemu_iovec_to_buf(qiov, qiov_offset, crypt_buf, bytes);
 
         if (qcow2_co_encrypt(bs, host_offset, offset, crypt_buf, bytes) < 0) {
             ret = -EIO;
             goto out_unlocked;
         }
 
         qemu_iovec_init_buf(&encrypted_qiov, crypt_buf, bytes);
         qiov = &encrypted_qiov;
         qiov_offset = 0;
     }
 
     /* Try to efficiently initialize the physical space with zeroes */
     ret = handle_alloc_space(bs, l2meta);
     if (ret < 0) {
         goto out_unlocked;
     }
 
     /*
      * If we need to do COW, check if it's possible to merge the
      * writing of the guest data together with that of the COW regions.
      * If it's not possible (or not necessary) then write the
      * guest data now.
      */
     if (!merge_cow(offset, bytes, qiov, qiov_offset, l2meta)) {
         BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
         trace_qcow2_writev_data(qemu_coroutine_self(), host_offset);
         ret = bdrv_co_pwritev_part(s->data_file, host_offset,
                                    bytes, qiov, qiov_offset, 0);
         if (ret < 0) {
             goto out_unlocked;
         }
     }
 
     qemu_co_mutex_lock(&s->lock);
 
     ret = qcow2_handle_l2meta(bs, &l2meta, true);
     goto out_locked;
 
 out_unlocked:
     qemu_co_mutex_lock(&s->lock);
 
 out_locked:
     qcow2_handle_l2meta(bs, &l2meta, false);
     qemu_co_mutex_unlock(&s->lock);
 
     qemu_vfree(crypt_buf);
 
     return ret;
 }
 
 static coroutine_fn int qcow2_co_pwritev_task_entry(AioTask *task)
 {
     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
 
     assert(!t->subcluster_type);
 
     return qcow2_co_pwritev_task(t->bs, t->host_offset,
                                  t->offset, t->bytes, t->qiov, t->qiov_offset,
                                  t->l2meta);
 }
 
 static coroutine_fn int qcow2_co_pwritev_part(
         BlockDriverState *bs, int64_t offset, int64_t bytes,
         QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags)
 {
     BDRVQcow2State *s = bs->opaque;
     int offset_in_cluster;
     int ret;
     unsigned int cur_bytes; /* number of sectors in current iteration */
     uint64_t host_offset;
     QCowL2Meta *l2meta = NULL;
     AioTaskPool *aio = NULL;
 
     trace_qcow2_writev_start_req(qemu_coroutine_self(), offset, bytes);
 
     while (bytes != 0 && aio_task_pool_status(aio) == 0) {
 
         l2meta = NULL;
 
         trace_qcow2_writev_start_part(qemu_coroutine_self());
         offset_in_cluster = offset_into_cluster(s, offset);
         cur_bytes = MIN(bytes, INT_MAX);
         if (bs->encrypted) {
             cur_bytes = MIN(cur_bytes,
                             QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
                             - offset_in_cluster);
         }
 
         qemu_co_mutex_lock(&s->lock);
 
         ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
                                       &host_offset, &l2meta);
         if (ret < 0) {
             goto out_locked;
         }
 
         ret = qcow2_pre_write_overlap_check(bs, 0, host_offset,
                                             cur_bytes, true);
         if (ret < 0) {
             goto out_locked;
         }
 
         qemu_co_mutex_unlock(&s->lock);
 
         if (!aio && cur_bytes != bytes) {
             aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
         }
         ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_task_entry, 0,
                              host_offset, offset,
                              cur_bytes, qiov, qiov_offset, l2meta);
         l2meta = NULL; /* l2meta is consumed by qcow2_co_pwritev_task() */
         if (ret < 0) {
             goto fail_nometa;
         }
 
         bytes -= cur_bytes;
         offset += cur_bytes;
         qiov_offset += cur_bytes;
         trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_bytes);
     }
     ret = 0;
 
     qemu_co_mutex_lock(&s->lock);
 
 out_locked:
     qcow2_handle_l2meta(bs, &l2meta, false);
 
     qemu_co_mutex_unlock(&s->lock);
 
 fail_nometa:
     if (aio) {
         aio_task_pool_wait_all(aio);
         if (ret == 0) {
             ret = aio_task_pool_status(aio);
         }
         g_free(aio);
     }
 
     trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
 
     return ret;
 }
 
 static int qcow2_inactivate(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret, result = 0;
     Error *local_err = NULL;
 
     qcow2_store_persistent_dirty_bitmaps(bs, true, &local_err);
     if (local_err != NULL) {
         result = -EINVAL;
         error_reportf_err(local_err, "Lost persistent bitmaps during "
                           "inactivation of node '%s': ",
                           bdrv_get_device_or_node_name(bs));
     }
 
     ret = qcow2_cache_flush(bs, s->l2_table_cache);
     if (ret) {
         result = ret;
         error_report("Failed to flush the L2 table cache: %s",
                      strerror(-ret));
     }
 
     ret = qcow2_cache_flush(bs, s->refcount_block_cache);
     if (ret) {
         result = ret;
         error_report("Failed to flush the refcount block cache: %s",
                      strerror(-ret));
     }
 
     if (result == 0) {
         qcow2_mark_clean(bs);
     }
 
     return result;
 }
 
 static void qcow2_do_close(BlockDriverState *bs, bool close_data_file)
 {
     BDRVQcow2State *s = bs->opaque;
     qemu_vfree(s->l1_table);
     /* else pre-write overlap checks in cache_destroy may crash */
     s->l1_table = NULL;
 
     if (!(s->flags & BDRV_O_INACTIVE)) {
         qcow2_inactivate(bs);
     }
 
     cache_clean_timer_del(bs);
     qcow2_cache_destroy(s->l2_table_cache);
     qcow2_cache_destroy(s->refcount_block_cache);
 
     qcrypto_block_free(s->crypto);
     s->crypto = NULL;
     qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
 
     g_free(s->unknown_header_fields);
     cleanup_unknown_header_ext(bs);
 
     g_free(s->image_data_file);
     g_free(s->image_backing_file);
     g_free(s->image_backing_format);
 
     if (close_data_file && has_data_file(bs)) {
         bdrv_unref_child(bs, s->data_file);
         s->data_file = NULL;
     }
 
     qcow2_refcount_close(bs);
     qcow2_free_snapshots(bs);
 }
 
 static void qcow2_close(BlockDriverState *bs)
 {
     qcow2_do_close(bs, true);
 }
 
 static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs,
                                                    Error **errp)
 {
     ERRP_GUARD();
     BDRVQcow2State *s = bs->opaque;
     BdrvChild *data_file;
     int flags = s->flags;
     QCryptoBlock *crypto = NULL;
     QDict *options;
     int ret;
 
     /*
      * Backing files are read-only which makes all of their metadata immutable,
      * that means we don't have to worry about reopening them here.
      */
 
     crypto = s->crypto;
     s->crypto = NULL;
 
     /*
      * Do not reopen s->data_file (i.e., have qcow2_do_close() not close it,
      * and then prevent qcow2_do_open() from opening it), because this function
      * runs in the I/O path and as such we must not invoke global-state
      * functions like bdrv_unref_child() and bdrv_open_child().
      */
 
     qcow2_do_close(bs, false);
 
     data_file = s->data_file;
     memset(s, 0, sizeof(BDRVQcow2State));
     s->data_file = data_file;
 
     options = qdict_clone_shallow(bs->options);
 
     flags &= ~BDRV_O_INACTIVE;
     qemu_co_mutex_lock(&s->lock);
     ret = qcow2_do_open(bs, options, flags, false, errp);
     qemu_co_mutex_unlock(&s->lock);
     qobject_unref(options);
     if (ret < 0) {
         error_prepend(errp, "Could not reopen qcow2 layer: ");
         bs->drv = NULL;
         return;
     }
 
     s->crypto = crypto;
 }
 
 static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
     size_t len, size_t buflen)
 {
     QCowExtension *ext_backing_fmt = (QCowExtension*) buf;
     size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7);
 
     if (buflen < ext_len) {
         return -ENOSPC;
     }
 
     *ext_backing_fmt = (QCowExtension) {
         .magic  = cpu_to_be32(magic),
         .len    = cpu_to_be32(len),
     };
 
     if (len) {
         memcpy(buf + sizeof(QCowExtension), s, len);
     }
 
     return ext_len;
 }
 
 /*
  * Updates the qcow2 header, including the variable length parts of it, i.e.
  * the backing file name and all extensions. qcow2 was not designed to allow
  * such changes, so if we run out of space (we can only use the first cluster)
  * this function may fail.
  *
  * Returns 0 on success, -errno in error cases.
  */
 int qcow2_update_header(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     QCowHeader *header;
     char *buf;
     size_t buflen = s->cluster_size;
     int ret;
     uint64_t total_size;
     uint32_t refcount_table_clusters;
     size_t header_length;
     Qcow2UnknownHeaderExtension *uext;
 
     buf = qemu_blockalign(bs, buflen);
 
     /* Header structure */
     header = (QCowHeader*) buf;
 
     if (buflen < sizeof(*header)) {
         ret = -ENOSPC;
         goto fail;
     }
 
     header_length = sizeof(*header) + s->unknown_header_fields_size;
     total_size = bs->total_sectors * BDRV_SECTOR_SIZE;
     refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
 
     ret = validate_compression_type(s, NULL);
     if (ret) {
         goto fail;
     }
 
     *header = (QCowHeader) {
         /* Version 2 fields */
         .magic                  = cpu_to_be32(QCOW_MAGIC),
         .version                = cpu_to_be32(s->qcow_version),
         .backing_file_offset    = 0,
         .backing_file_size      = 0,
         .cluster_bits           = cpu_to_be32(s->cluster_bits),
         .size                   = cpu_to_be64(total_size),
         .crypt_method           = cpu_to_be32(s->crypt_method_header),
         .l1_size                = cpu_to_be32(s->l1_size),
         .l1_table_offset        = cpu_to_be64(s->l1_table_offset),
         .refcount_table_offset  = cpu_to_be64(s->refcount_table_offset),
         .refcount_table_clusters = cpu_to_be32(refcount_table_clusters),
         .nb_snapshots           = cpu_to_be32(s->nb_snapshots),
         .snapshots_offset       = cpu_to_be64(s->snapshots_offset),
 
         /* Version 3 fields */
         .incompatible_features  = cpu_to_be64(s->incompatible_features),
         .compatible_features    = cpu_to_be64(s->compatible_features),
         .autoclear_features     = cpu_to_be64(s->autoclear_features),
         .refcount_order         = cpu_to_be32(s->refcount_order),
         .header_length          = cpu_to_be32(header_length),
         .compression_type       = s->compression_type,
     };
 
     /* For older versions, write a shorter header */
     switch (s->qcow_version) {
     case 2:
         ret = offsetof(QCowHeader, incompatible_features);
         break;
     case 3:
         ret = sizeof(*header);
         break;
     default:
         ret = -EINVAL;
         goto fail;
     }
 
     buf += ret;
     buflen -= ret;
     memset(buf, 0, buflen);
 
     /* Preserve any unknown field in the header */
     if (s->unknown_header_fields_size) {
         if (buflen < s->unknown_header_fields_size) {
             ret = -ENOSPC;
             goto fail;
         }
 
         memcpy(buf, s->unknown_header_fields, s->unknown_header_fields_size);
         buf += s->unknown_header_fields_size;
         buflen -= s->unknown_header_fields_size;
     }
 
     /* Backing file format header extension */
     if (s->image_backing_format) {
         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BACKING_FORMAT,
                              s->image_backing_format,
                              strlen(s->image_backing_format),
                              buflen);
         if (ret < 0) {
             goto fail;
         }
 
         buf += ret;
         buflen -= ret;
     }
 
     /* External data file header extension */
     if (has_data_file(bs) && s->image_data_file) {
         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_DATA_FILE,
                              s->image_data_file, strlen(s->image_data_file),
                              buflen);
         if (ret < 0) {
             goto fail;
         }
 
         buf += ret;
         buflen -= ret;
     }
 
     /* Full disk encryption header pointer extension */
     if (s->crypto_header.offset != 0) {
         s->crypto_header.offset = cpu_to_be64(s->crypto_header.offset);
         s->crypto_header.length = cpu_to_be64(s->crypto_header.length);
         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_CRYPTO_HEADER,
                              &s->crypto_header, sizeof(s->crypto_header),
                              buflen);
         s->crypto_header.offset = be64_to_cpu(s->crypto_header.offset);
         s->crypto_header.length = be64_to_cpu(s->crypto_header.length);
         if (ret < 0) {
             goto fail;
         }
         buf += ret;
         buflen -= ret;
     }
 
     /*
      * Feature table.  A mere 8 feature names occupies 392 bytes, and
      * when coupled with the v3 minimum header of 104 bytes plus the
      * 8-byte end-of-extension marker, that would leave only 8 bytes
      * for a backing file name in an image with 512-byte clusters.
      * Thus, we choose to omit this header for cluster sizes 4k and
      * smaller.
      */
     if (s->qcow_version >= 3 && s->cluster_size > 4096) {
         static const Qcow2Feature features[] = {
             {
                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
                 .bit  = QCOW2_INCOMPAT_DIRTY_BITNR,
                 .name = "dirty bit",
             },
             {
                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
                 .bit  = QCOW2_INCOMPAT_CORRUPT_BITNR,
                 .name = "corrupt bit",
             },
             {
                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
                 .bit  = QCOW2_INCOMPAT_DATA_FILE_BITNR,
                 .name = "external data file",
             },
             {
                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
                 .bit  = QCOW2_INCOMPAT_COMPRESSION_BITNR,
                 .name = "compression type",
             },
             {
                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
                 .bit  = QCOW2_INCOMPAT_EXTL2_BITNR,
                 .name = "extended L2 entries",
             },
             {
                 .type = QCOW2_FEAT_TYPE_COMPATIBLE,
                 .bit  = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
                 .name = "lazy refcounts",
             },
             {
                 .type = QCOW2_FEAT_TYPE_AUTOCLEAR,
                 .bit  = QCOW2_AUTOCLEAR_BITMAPS_BITNR,
                 .name = "bitmaps",
             },
             {
                 .type = QCOW2_FEAT_TYPE_AUTOCLEAR,
                 .bit  = QCOW2_AUTOCLEAR_DATA_FILE_RAW_BITNR,
                 .name = "raw external data",
             },
         };
 
         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE,
                              features, sizeof(features), buflen);
         if (ret < 0) {
             goto fail;
         }
         buf += ret;
         buflen -= ret;
     }
 
     /* Bitmap extension */
     if (s->nb_bitmaps > 0) {
         Qcow2BitmapHeaderExt bitmaps_header = {
             .nb_bitmaps = cpu_to_be32(s->nb_bitmaps),
             .bitmap_directory_size =
                     cpu_to_be64(s->bitmap_directory_size),
             .bitmap_directory_offset =
                     cpu_to_be64(s->bitmap_directory_offset)
         };
         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BITMAPS,
                              &bitmaps_header, sizeof(bitmaps_header),
                              buflen);
         if (ret < 0) {
             goto fail;
         }
         buf += ret;
         buflen -= ret;
     }
 
     /* Keep unknown header extensions */
     QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
         ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen);
         if (ret < 0) {
             goto fail;
         }
 
         buf += ret;
         buflen -= ret;
     }
 
     /* End of header extensions */
     ret = header_ext_add(buf, QCOW2_EXT_MAGIC_END, NULL, 0, buflen);
     if (ret < 0) {
         goto fail;
     }
 
     buf += ret;
     buflen -= ret;
 
     /* Backing file name */
     if (s->image_backing_file) {
         size_t backing_file_len = strlen(s->image_backing_file);
 
         if (buflen < backing_file_len) {
             ret = -ENOSPC;
             goto fail;
         }
 
         /* Using strncpy is ok here, since buf is not NUL-terminated. */
         strncpy(buf, s->image_backing_file, buflen);
 
         header->backing_file_offset = cpu_to_be64(buf - ((char*) header));
         header->backing_file_size   = cpu_to_be32(backing_file_len);
     }
 
     /* Write the new header */
     ret = bdrv_pwrite(bs->file, 0, s->cluster_size, header, 0);
     if (ret < 0) {
         goto fail;
     }
 
     ret = 0;
 fail:
     qemu_vfree(header);
     return ret;
 }
 
 static int qcow2_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt)
 {
     BDRVQcow2State *s = bs->opaque;
 
     /* Adding a backing file means that the external data file alone won't be
      * enough to make sense of the content */
     if (backing_file && data_file_is_raw(bs)) {
         return -EINVAL;
     }
 
     if (backing_file && strlen(backing_file) > 1023) {
         return -EINVAL;
     }
 
     pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
             backing_file ?: "");
     pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
     pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
 
     g_free(s->image_backing_file);
     g_free(s->image_backing_format);
 
     s->image_backing_file = backing_file ? g_strdup(bs->backing_file) : NULL;
     s->image_backing_format = backing_fmt ? g_strdup(bs->backing_format) : NULL;
 
     return qcow2_update_header(bs);
 }
 
 static int qcow2_set_up_encryption(BlockDriverState *bs,
                                    QCryptoBlockCreateOptions *cryptoopts,
                                    Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     QCryptoBlock *crypto = NULL;
     int fmt, ret;
 
     switch (cryptoopts->format) {
     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
         fmt = QCOW_CRYPT_LUKS;
         break;
     case Q_CRYPTO_BLOCK_FORMAT_QCOW:
         fmt = QCOW_CRYPT_AES;
         break;
     default:
         error_setg(errp, "Crypto format not supported in qcow2");
         return -EINVAL;
     }
 
     s->crypt_method_header = fmt;
 
     crypto = qcrypto_block_create(cryptoopts, "encrypt.",
                                   qcow2_crypto_hdr_init_func,
                                   qcow2_crypto_hdr_write_func,
                                   bs, errp);
     if (!crypto) {
         return -EINVAL;
     }
 
     ret = qcow2_update_header(bs);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write encryption header");
         goto out;
     }
 
     ret = 0;
  out:
     qcrypto_block_free(crypto);
     return ret;
 }
 
 /**
  * Preallocates metadata structures for data clusters between @offset (in the
  * guest disk) and @new_length (which is thus generally the new guest disk
  * size).
  *
  * Returns: 0 on success, -errno on failure.
  */
 static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
                                        uint64_t new_length, PreallocMode mode,
                                        Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t bytes;
     uint64_t host_offset = 0;
     int64_t file_length;
     unsigned int cur_bytes;
     int ret;
     QCowL2Meta *meta = NULL, *m;
 
     assert(offset <= new_length);
     bytes = new_length - offset;
 
     while (bytes) {
         cur_bytes = MIN(bytes, QEMU_ALIGN_DOWN(INT_MAX, s->cluster_size));
         ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
                                       &host_offset, &meta);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Allocating clusters failed");
             goto out;
         }
 
         for (m = meta; m != NULL; m = m->next) {
             m->prealloc = true;
         }
 
         ret = qcow2_handle_l2meta(bs, &meta, true);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Mapping clusters failed");
             goto out;
         }
 
         /* TODO Preallocate data if requested */
 
         bytes -= cur_bytes;
         offset += cur_bytes;
     }
 
     /*
      * It is expected that the image file is large enough to actually contain
      * all of the allocated clusters (otherwise we get failing reads after
      * EOF). Extend the image to the last allocated sector.
      */
     file_length = bdrv_getlength(s->data_file->bs);
     if (file_length < 0) {
         error_setg_errno(errp, -file_length, "Could not get file size");
         ret = file_length;
         goto out;
     }
 
     if (host_offset + cur_bytes > file_length) {
         if (mode == PREALLOC_MODE_METADATA) {
             mode = PREALLOC_MODE_OFF;
         }
         ret = bdrv_co_truncate(s->data_file, host_offset + cur_bytes, false,
                                mode, 0, errp);
         if (ret < 0) {
             goto out;
         }
     }
 
     ret = 0;
 
 out:
     qcow2_handle_l2meta(bs, &meta, false);
     return ret;
 }
 
 /* qcow2_refcount_metadata_size:
  * @clusters: number of clusters to refcount (including data and L1/L2 tables)
  * @cluster_size: size of a cluster, in bytes
  * @refcount_order: refcount bits power-of-2 exponent
  * @generous_increase: allow for the refcount table to be 1.5x as large as it
  *                     needs to be
  *
  * Returns: Number of bytes required for refcount blocks and table metadata.
  */
 int64_t qcow2_refcount_metadata_size(int64_t clusters, size_t cluster_size,
                                      int refcount_order, bool generous_increase,
                                      uint64_t *refblock_count)
 {
     /*
      * Every host cluster is reference-counted, including metadata (even
      * refcount metadata is recursively included).
      *
      * An accurate formula for the size of refcount metadata size is difficult
      * to derive.  An easier method of calculation is finding the fixed point
      * where no further refcount blocks or table clusters are required to
      * reference count every cluster.
      */
     int64_t blocks_per_table_cluster = cluster_size / REFTABLE_ENTRY_SIZE;
     int64_t refcounts_per_block = cluster_size * 8 / (1 << refcount_order);
     int64_t table = 0;  /* number of refcount table clusters */
     int64_t blocks = 0; /* number of refcount block clusters */
     int64_t last;
     int64_t n = 0;
 
     do {
         last = n;
         blocks = DIV_ROUND_UP(clusters + table + blocks, refcounts_per_block);
         table = DIV_ROUND_UP(blocks, blocks_per_table_cluster);
         n = clusters + blocks + table;
 
         if (n == last && generous_increase) {
             clusters += DIV_ROUND_UP(table, 2);
             n = 0; /* force another loop */
             generous_increase = false;
         }
     } while (n != last);
 
     if (refblock_count) {
         *refblock_count = blocks;
     }
 
     return (blocks + table) * cluster_size;
 }
 
 /**
  * qcow2_calc_prealloc_size:
  * @total_size: virtual disk size in bytes
  * @cluster_size: cluster size in bytes
  * @refcount_order: refcount bits power-of-2 exponent
  * @extended_l2: true if the image has extended L2 entries
  *
  * Returns: Total number of bytes required for the fully allocated image
  * (including metadata).
  */
 static int64_t qcow2_calc_prealloc_size(int64_t total_size,
                                         size_t cluster_size,
                                         int refcount_order,
                                         bool extended_l2)
 {
     int64_t meta_size = 0;
     uint64_t nl1e, nl2e;
     int64_t aligned_total_size = ROUND_UP(total_size, cluster_size);
     size_t l2e_size = extended_l2 ? L2E_SIZE_EXTENDED : L2E_SIZE_NORMAL;
 
     /* header: 1 cluster */
     meta_size += cluster_size;
 
     /* total size of L2 tables */
     nl2e = aligned_total_size / cluster_size;
     nl2e = ROUND_UP(nl2e, cluster_size / l2e_size);
     meta_size += nl2e * l2e_size;
 
     /* total size of L1 tables */
     nl1e = nl2e * l2e_size / cluster_size;
     nl1e = ROUND_UP(nl1e, cluster_size / L1E_SIZE);
     meta_size += nl1e * L1E_SIZE;
 
     /* total size of refcount table and blocks */
     meta_size += qcow2_refcount_metadata_size(
             (meta_size + aligned_total_size) / cluster_size,
             cluster_size, refcount_order, false, NULL);
 
     return meta_size + aligned_total_size;
 }
 
 static bool validate_cluster_size(size_t cluster_size, bool extended_l2,
                                   Error **errp)
 {
     int cluster_bits = ctz32(cluster_size);
     if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS ||
         (1 << cluster_bits) != cluster_size)
     {
         error_setg(errp, "Cluster size must be a power of two between %d and "
                    "%dk", 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
         return false;
     }
 
     if (extended_l2) {
         unsigned min_cluster_size =
             (1 << MIN_CLUSTER_BITS) * QCOW_EXTL2_SUBCLUSTERS_PER_CLUSTER;
         if (cluster_size < min_cluster_size) {
             error_setg(errp, "Extended L2 entries are only supported with "
                        "cluster sizes of at least %u bytes", min_cluster_size);
             return false;
         }
     }
 
     return true;
 }
 
 static size_t qcow2_opt_get_cluster_size_del(QemuOpts *opts, bool extended_l2,
                                              Error **errp)
 {
     size_t cluster_size;
 
     cluster_size = qemu_opt_get_size_del(opts, BLOCK_OPT_CLUSTER_SIZE,
                                          DEFAULT_CLUSTER_SIZE);
     if (!validate_cluster_size(cluster_size, extended_l2, errp)) {
         return 0;
     }
     return cluster_size;
 }
 
 static int qcow2_opt_get_version_del(QemuOpts *opts, Error **errp)
 {
     char *buf;
     int ret;
 
     buf = qemu_opt_get_del(opts, BLOCK_OPT_COMPAT_LEVEL);
     if (!buf) {
         ret = 3; /* default */
     } else if (!strcmp(buf, "0.10")) {
         ret = 2;
     } else if (!strcmp(buf, "1.1")) {
         ret = 3;
     } else {
         error_setg(errp, "Invalid compatibility level: '%s'", buf);
         ret = -EINVAL;
     }
     g_free(buf);
     return ret;
 }
 
 static uint64_t qcow2_opt_get_refcount_bits_del(QemuOpts *opts, int version,
                                                 Error **errp)
 {
     uint64_t refcount_bits;
 
     refcount_bits = qemu_opt_get_number_del(opts, BLOCK_OPT_REFCOUNT_BITS, 16);
     if (refcount_bits > 64 || !is_power_of_2(refcount_bits)) {
         error_setg(errp, "Refcount width must be a power of two and may not "
                    "exceed 64 bits");
         return 0;
     }
 
     if (version < 3 && refcount_bits != 16) {
         error_setg(errp, "Different refcount widths than 16 bits require "
                    "compatibility level 1.1 or above (use compat=1.1 or "
                    "greater)");
         return 0;
     }
 
     return refcount_bits;
 }
 
 static int coroutine_fn
 qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
 {
     BlockdevCreateOptionsQcow2 *qcow2_opts;
     QDict *options;
 
     /*
      * Open the image file and write a minimal qcow2 header.
      *
      * We keep things simple and start with a zero-sized image. We also
      * do without refcount blocks or a L1 table for now. We'll fix the
      * inconsistency later.
      *
      * We do need a refcount table because growing the refcount table means
      * allocating two new refcount blocks - the second of which would be at
      * 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
      * size for any qcow2 image.
      */
     BlockBackend *blk = NULL;
     BlockDriverState *bs = NULL;
     BlockDriverState *data_bs = NULL;
     QCowHeader *header;
     size_t cluster_size;
     int version;
     int refcount_order;
     uint64_t *refcount_table;
     int ret;
     uint8_t compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
 
     assert(create_options->driver == BLOCKDEV_DRIVER_QCOW2);
     qcow2_opts = &create_options->u.qcow2;
 
     bs = bdrv_open_blockdev_ref(qcow2_opts->file, errp);
     if (bs == NULL) {
         return -EIO;
     }
 
     /* Validate options and set default values */
     if (!QEMU_IS_ALIGNED(qcow2_opts->size, BDRV_SECTOR_SIZE)) {
         error_setg(errp, "Image size must be a multiple of %u bytes",
                    (unsigned) BDRV_SECTOR_SIZE);
         ret = -EINVAL;
         goto out;
     }
 
     if (qcow2_opts->has_version) {
         switch (qcow2_opts->version) {
         case BLOCKDEV_QCOW2_VERSION_V2:
             version = 2;
             break;
         case BLOCKDEV_QCOW2_VERSION_V3:
             version = 3;
             break;
         default:
             g_assert_not_reached();
         }
     } else {
         version = 3;
     }
 
     if (qcow2_opts->has_cluster_size) {
         cluster_size = qcow2_opts->cluster_size;
     } else {
         cluster_size = DEFAULT_CLUSTER_SIZE;
     }
 
     if (!qcow2_opts->has_extended_l2) {
         qcow2_opts->extended_l2 = false;
     }
     if (qcow2_opts->extended_l2) {
         if (version < 3) {
             error_setg(errp, "Extended L2 entries are only supported with "
                        "compatibility level 1.1 and above (use version=v3 or "
                        "greater)");
             ret = -EINVAL;
             goto out;
         }
     }
 
     if (!validate_cluster_size(cluster_size, qcow2_opts->extended_l2, errp)) {
         ret = -EINVAL;
         goto out;
     }
 
     if (!qcow2_opts->has_preallocation) {
         qcow2_opts->preallocation = PREALLOC_MODE_OFF;
     }
     if (qcow2_opts->has_backing_file &&
         qcow2_opts->preallocation != PREALLOC_MODE_OFF &&
         !qcow2_opts->extended_l2)
     {
         error_setg(errp, "Backing file and preallocation can only be used at "
                    "the same time if extended_l2 is on");
         ret = -EINVAL;
         goto out;
     }
     if (qcow2_opts->has_backing_fmt && !qcow2_opts->has_backing_file) {
         error_setg(errp, "Backing format cannot be used without backing file");
         ret = -EINVAL;
         goto out;
     }
 
     if (!qcow2_opts->has_lazy_refcounts) {
         qcow2_opts->lazy_refcounts = false;
     }
     if (version < 3 && qcow2_opts->lazy_refcounts) {
         error_setg(errp, "Lazy refcounts only supported with compatibility "
                    "level 1.1 and above (use version=v3 or greater)");
         ret = -EINVAL;
         goto out;
     }
 
     if (!qcow2_opts->has_refcount_bits) {
         qcow2_opts->refcount_bits = 16;
     }
     if (qcow2_opts->refcount_bits > 64 ||
         !is_power_of_2(qcow2_opts->refcount_bits))
     {
         error_setg(errp, "Refcount width must be a power of two and may not "
                    "exceed 64 bits");
         ret = -EINVAL;
         goto out;
     }
     if (version < 3 && qcow2_opts->refcount_bits != 16) {
         error_setg(errp, "Different refcount widths than 16 bits require "
                    "compatibility level 1.1 or above (use version=v3 or "
                    "greater)");
         ret = -EINVAL;
         goto out;
     }
     refcount_order = ctz32(qcow2_opts->refcount_bits);
 
     if (qcow2_opts->data_file_raw && !qcow2_opts->data_file) {
         error_setg(errp, "data-file-raw requires data-file");
         ret = -EINVAL;
         goto out;
     }
     if (qcow2_opts->data_file_raw && qcow2_opts->has_backing_file) {
         error_setg(errp, "Backing file and data-file-raw cannot be used at "
                    "the same time");
         ret = -EINVAL;
         goto out;
     }
     if (qcow2_opts->data_file_raw &&
         qcow2_opts->preallocation == PREALLOC_MODE_OFF)
     {
         /*
          * data-file-raw means that "the external data file can be
          * read as a consistent standalone raw image without looking
          * at the qcow2 metadata."  It does not say that the metadata
          * must be ignored, though (and the qcow2 driver in fact does
          * not ignore it), so the L1/L2 tables must be present and
          * give a 1:1 mapping, so you get the same result regardless
          * of whether you look at the metadata or whether you ignore
          * it.
          */
         qcow2_opts->preallocation = PREALLOC_MODE_METADATA;
 
         /*
          * Cannot use preallocation with backing files, but giving a
          * backing file when specifying data_file_raw is an error
          * anyway.
          */
         assert(!qcow2_opts->has_backing_file);
     }
 
     if (qcow2_opts->data_file) {
         if (version < 3) {
             error_setg(errp, "External data files are only supported with "
                        "compatibility level 1.1 and above (use version=v3 or "
                        "greater)");
             ret = -EINVAL;
             goto out;
         }
         data_bs = bdrv_open_blockdev_ref(qcow2_opts->data_file, errp);
         if (data_bs == NULL) {
             ret = -EIO;
             goto out;
         }
     }
 
     if (qcow2_opts->has_compression_type &&
         qcow2_opts->compression_type != QCOW2_COMPRESSION_TYPE_ZLIB) {
 
         ret = -EINVAL;
 
         if (version < 3) {
             error_setg(errp, "Non-zlib compression type is only supported with "
                        "compatibility level 1.1 and above (use version=v3 or "
                        "greater)");
             goto out;
         }
 
         switch (qcow2_opts->compression_type) {
 #ifdef CONFIG_ZSTD
         case QCOW2_COMPRESSION_TYPE_ZSTD:
             break;
 #endif
         default:
             error_setg(errp, "Unknown compression type");
             goto out;
         }
 
         compression_type = qcow2_opts->compression_type;
     }
 
     /* Create BlockBackend to write to the image */
     blk = blk_new_with_bs(bs, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL,
                           errp);
     if (!blk) {
         ret = -EPERM;
         goto out;
     }
     blk_set_allow_write_beyond_eof(blk, true);
 
     /* Write the header */
     QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
     header = g_malloc0(cluster_size);
     *header = (QCowHeader) {
         .magic                      = cpu_to_be32(QCOW_MAGIC),
         .version                    = cpu_to_be32(version),
         .cluster_bits               = cpu_to_be32(ctz32(cluster_size)),
         .size                       = cpu_to_be64(0),
         .l1_table_offset            = cpu_to_be64(0),
         .l1_size                    = cpu_to_be32(0),
         .refcount_table_offset      = cpu_to_be64(cluster_size),
         .refcount_table_clusters    = cpu_to_be32(1),
         .refcount_order             = cpu_to_be32(refcount_order),
         /* don't deal with endianness since compression_type is 1 byte long */
         .compression_type           = compression_type,
         .header_length              = cpu_to_be32(sizeof(*header)),
     };
 
     /* We'll update this to correct value later */
     header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 
     if (qcow2_opts->lazy_refcounts) {
         header->compatible_features |=
             cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
     }
     if (data_bs) {
         header->incompatible_features |=
             cpu_to_be64(QCOW2_INCOMPAT_DATA_FILE);
     }
     if (qcow2_opts->data_file_raw) {
         header->autoclear_features |=
             cpu_to_be64(QCOW2_AUTOCLEAR_DATA_FILE_RAW);
     }
     if (compression_type != QCOW2_COMPRESSION_TYPE_ZLIB) {
         header->incompatible_features |=
             cpu_to_be64(QCOW2_INCOMPAT_COMPRESSION);
     }
 
     if (qcow2_opts->extended_l2) {
         header->incompatible_features |=
             cpu_to_be64(QCOW2_INCOMPAT_EXTL2);
     }
 
     ret = blk_co_pwrite(blk, 0, cluster_size, header, 0);
     g_free(header);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write qcow2 header");
         goto out;
     }
 
     /* Write a refcount table with one refcount block */
     refcount_table = g_malloc0(2 * cluster_size);
     refcount_table[0] = cpu_to_be64(2 * cluster_size);
     ret = blk_co_pwrite(blk, cluster_size, 2 * cluster_size, refcount_table, 0);
     g_free(refcount_table);
 
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write refcount table");
         goto out;
     }
 
     blk_unref(blk);
     blk = NULL;
 
     /*
      * And now open the image and make it consistent first (i.e. increase the
      * refcount of the cluster that is occupied by the header and the refcount
      * table)
      */
     options = qdict_new();
     qdict_put_str(options, "driver", "qcow2");
     qdict_put_str(options, "file", bs->node_name);
     if (data_bs) {
         qdict_put_str(options, "data-file", data_bs->node_name);
     }
     blk = blk_new_open(NULL, NULL, options,
                        BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_NO_FLUSH,
                        errp);
     if (blk == NULL) {
         ret = -EIO;
         goto out;
     }
 
     ret = qcow2_alloc_clusters(blk_bs(blk), 3 * cluster_size);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not allocate clusters for qcow2 "
                          "header and refcount table");
         goto out;
 
     } else if (ret != 0) {
         error_report("Huh, first cluster in empty image is already in use?");
         abort();
     }
 
     /* Set the external data file if necessary */
     if (data_bs) {
         BDRVQcow2State *s = blk_bs(blk)->opaque;
         s->image_data_file = g_strdup(data_bs->filename);
     }
 
     /* Create a full header (including things like feature table) */
     ret = qcow2_update_header(blk_bs(blk));
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not update qcow2 header");
         goto out;
     }
 
     /* Okay, now that we have a valid image, let's give it the right size */
     ret = blk_co_truncate(blk, qcow2_opts->size, false,
                           qcow2_opts->preallocation, 0, errp);
     if (ret < 0) {
         error_prepend(errp, "Could not resize image: ");
         goto out;
     }
 
     /* Want a backing file? There you go. */
     if (qcow2_opts->has_backing_file) {
         const char *backing_format = NULL;
 
         if (qcow2_opts->has_backing_fmt) {
             backing_format = BlockdevDriver_str(qcow2_opts->backing_fmt);
         }
 
         ret = bdrv_change_backing_file(blk_bs(blk), qcow2_opts->backing_file,
                                        backing_format, false);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Could not assign backing file '%s' "
                              "with format '%s'", qcow2_opts->backing_file,
                              backing_format);
             goto out;
         }
     }
 
     /* Want encryption? There you go. */
     if (qcow2_opts->has_encrypt) {
         ret = qcow2_set_up_encryption(blk_bs(blk), qcow2_opts->encrypt, errp);
         if (ret < 0) {
             goto out;
         }
     }
 
     blk_unref(blk);
     blk = NULL;
 
     /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning.
      * Using BDRV_O_NO_IO, since encryption is now setup we don't want to
      * have to setup decryption context. We're not doing any I/O on the top
      * level BlockDriverState, only lower layers, where BDRV_O_NO_IO does
      * not have effect.
      */
     options = qdict_new();
     qdict_put_str(options, "driver", "qcow2");
     qdict_put_str(options, "file", bs->node_name);
     if (data_bs) {
         qdict_put_str(options, "data-file", data_bs->node_name);
     }
     blk = blk_new_open(NULL, NULL, options,
                        BDRV_O_RDWR | BDRV_O_NO_BACKING | BDRV_O_NO_IO,
                        errp);
     if (blk == NULL) {
         ret = -EIO;
         goto out;
     }
 
     ret = 0;
 out:
     blk_unref(blk);
     bdrv_unref(bs);
     bdrv_unref(data_bs);
     return ret;
 }
 
 static int coroutine_fn qcow2_co_create_opts(BlockDriver *drv,
                                              const char *filename,
                                              QemuOpts *opts,
                                              Error **errp)
 {
     BlockdevCreateOptions *create_options = NULL;
     QDict *qdict;
     Visitor *v;
     BlockDriverState *bs = NULL;
     BlockDriverState *data_bs = NULL;
     const char *val;
     int ret;
 
     /* Only the keyval visitor supports the dotted syntax needed for
      * encryption, so go through a QDict before getting a QAPI type. Ignore
      * options meant for the protocol layer so that the visitor doesn't
      * complain. */
     qdict = qemu_opts_to_qdict_filtered(opts, NULL, bdrv_qcow2.create_opts,
                                         true);
 
     /* Handle encryption options */
     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT);
     if (val && !strcmp(val, "on")) {
         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT, "qcow");
     } else if (val && !strcmp(val, "off")) {
         qdict_del(qdict, BLOCK_OPT_ENCRYPT);
     }
 
     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT);
     if (val && !strcmp(val, "aes")) {
         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT, "qcow");
     }
 
     /* Convert compat=0.10/1.1 into compat=v2/v3, to be renamed into
      * version=v2/v3 below. */
     val = qdict_get_try_str(qdict, BLOCK_OPT_COMPAT_LEVEL);
     if (val && !strcmp(val, "0.10")) {
         qdict_put_str(qdict, BLOCK_OPT_COMPAT_LEVEL, "v2");
     } else if (val && !strcmp(val, "1.1")) {
         qdict_put_str(qdict, BLOCK_OPT_COMPAT_LEVEL, "v3");
     }
 
     /* Change legacy command line options into QMP ones */
     static const QDictRenames opt_renames[] = {
         { BLOCK_OPT_BACKING_FILE,       "backing-file" },
         { BLOCK_OPT_BACKING_FMT,        "backing-fmt" },
         { BLOCK_OPT_CLUSTER_SIZE,       "cluster-size" },
         { BLOCK_OPT_LAZY_REFCOUNTS,     "lazy-refcounts" },
         { BLOCK_OPT_EXTL2,              "extended-l2" },
         { BLOCK_OPT_REFCOUNT_BITS,      "refcount-bits" },
         { BLOCK_OPT_ENCRYPT,            BLOCK_OPT_ENCRYPT_FORMAT },
         { BLOCK_OPT_COMPAT_LEVEL,       "version" },
         { BLOCK_OPT_DATA_FILE_RAW,      "data-file-raw" },
         { BLOCK_OPT_COMPRESSION_TYPE,   "compression-type" },
         { NULL, NULL },
     };
 
     if (!qdict_rename_keys(qdict, opt_renames, errp)) {
         ret = -EINVAL;
         goto finish;
     }
 
     /* Create and open the file (protocol layer) */
     ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
         goto finish;
     }
 
     bs = bdrv_open(filename, NULL, NULL,
                    BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
     if (bs == NULL) {
         ret = -EIO;
         goto finish;
     }
 
     /* Create and open an external data file (protocol layer) */
     val = qdict_get_try_str(qdict, BLOCK_OPT_DATA_FILE);
     if (val) {
         ret = bdrv_create_file(val, opts, errp);
         if (ret < 0) {
             goto finish;
         }
 
         data_bs = bdrv_open(val, NULL, NULL,
                             BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
                             errp);
         if (data_bs == NULL) {
             ret = -EIO;
             goto finish;
         }
 
         qdict_del(qdict, BLOCK_OPT_DATA_FILE);
         qdict_put_str(qdict, "data-file", data_bs->node_name);
     }
 
     /* Set 'driver' and 'node' options */
     qdict_put_str(qdict, "driver", "qcow2");
     qdict_put_str(qdict, "file", bs->node_name);
 
     /* Now get the QAPI type BlockdevCreateOptions */
     v = qobject_input_visitor_new_flat_confused(qdict, errp);
     if (!v) {
         ret = -EINVAL;
         goto finish;
     }
 
     visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
     visit_free(v);
     if (!create_options) {
         ret = -EINVAL;
         goto finish;
     }
 
     /* Silently round up size */
     create_options->u.qcow2.size = ROUND_UP(create_options->u.qcow2.size,
                                             BDRV_SECTOR_SIZE);
 
     /* Create the qcow2 image (format layer) */
     ret = qcow2_co_create(create_options, errp);
 finish:
     if (ret < 0) {
         bdrv_co_delete_file_noerr(bs);
         bdrv_co_delete_file_noerr(data_bs);
     } else {
         ret = 0;
     }
 
     qobject_unref(qdict);
     bdrv_unref(bs);
     bdrv_unref(data_bs);
     qapi_free_BlockdevCreateOptions(create_options);
     return ret;
 }
 
 
 static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
 {
     int64_t nr;
     int res;
 
     /* Clamp to image length, before checking status of underlying sectors */
     if (offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) {
         bytes = bs->total_sectors * BDRV_SECTOR_SIZE - offset;
     }
 
     if (!bytes) {
         return true;
     }
 
     /*
      * bdrv_block_status_above doesn't merge different types of zeros, for
      * example, zeros which come from the region which is unallocated in
      * the whole backing chain, and zeros which come because of a short
      * backing file. So, we need a loop.
      */
     do {
         res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
         offset += nr;
         bytes -= nr;
     } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes);
 
     return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0;
 }
 
 static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs,
     int64_t offset, int64_t bytes, BdrvRequestFlags flags)
 {
     int ret;
     BDRVQcow2State *s = bs->opaque;
 
     uint32_t head = offset_into_subcluster(s, offset);
     uint32_t tail = ROUND_UP(offset + bytes, s->subcluster_size) -
         (offset + bytes);
 
     trace_qcow2_pwrite_zeroes_start_req(qemu_coroutine_self(), offset, bytes);
     if (offset + bytes == bs->total_sectors * BDRV_SECTOR_SIZE) {
         tail = 0;
     }
 
     if (head || tail) {
         uint64_t off;
         unsigned int nr;
         QCow2SubclusterType type;
 
         assert(head + bytes + tail <= s->subcluster_size);
 
         /* check whether remainder of cluster already reads as zero */
         if (!(is_zero(bs, offset - head, head) &&
               is_zero(bs, offset + bytes, tail))) {
             return -ENOTSUP;
         }
 
         qemu_co_mutex_lock(&s->lock);
         /* We can have new write after previous check */
         offset -= head;
         bytes = s->subcluster_size;
         nr = s->subcluster_size;
         ret = qcow2_get_host_offset(bs, offset, &nr, &off, &type);
         if (ret < 0 ||
             (type != QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN &&
              type != QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC &&
              type != QCOW2_SUBCLUSTER_ZERO_PLAIN &&
              type != QCOW2_SUBCLUSTER_ZERO_ALLOC)) {
             qemu_co_mutex_unlock(&s->lock);
             return ret < 0 ? ret : -ENOTSUP;
         }
     } else {
         qemu_co_mutex_lock(&s->lock);
     }
 
     trace_qcow2_pwrite_zeroes(qemu_coroutine_self(), offset, bytes);
 
     /* Whatever is left can use real zero subclusters */
     ret = qcow2_subcluster_zeroize(bs, offset, bytes, flags);
     qemu_co_mutex_unlock(&s->lock);
 
     return ret;
 }
 
 static coroutine_fn int qcow2_co_pdiscard(BlockDriverState *bs,
                                           int64_t offset, int64_t bytes)
 {
     int ret;
     BDRVQcow2State *s = bs->opaque;
 
     /* If the image does not support QCOW_OFLAG_ZERO then discarding
      * clusters could expose stale data from the backing file. */
     if (s->qcow_version < 3 && bs->backing) {
         return -ENOTSUP;
     }
 
     if (!QEMU_IS_ALIGNED(offset | bytes, s->cluster_size)) {
         assert(bytes < s->cluster_size);
         /* Ignore partial clusters, except for the special case of the
          * complete partial cluster at the end of an unaligned file */
         if (!QEMU_IS_ALIGNED(offset, s->cluster_size) ||
             offset + bytes != bs->total_sectors * BDRV_SECTOR_SIZE) {
             return -ENOTSUP;
         }
     }
 
     qemu_co_mutex_lock(&s->lock);
     ret = qcow2_cluster_discard(bs, offset, bytes, QCOW2_DISCARD_REQUEST,
                                 false);
     qemu_co_mutex_unlock(&s->lock);
     return ret;
 }
 
 static int coroutine_fn
 qcow2_co_copy_range_from(BlockDriverState *bs,
                          BdrvChild *src, int64_t src_offset,
                          BdrvChild *dst, int64_t dst_offset,
                          int64_t bytes, BdrvRequestFlags read_flags,
                          BdrvRequestFlags write_flags)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret;
     unsigned int cur_bytes; /* number of bytes in current iteration */
     BdrvChild *child = NULL;
     BdrvRequestFlags cur_write_flags;
 
     assert(!bs->encrypted);
     qemu_co_mutex_lock(&s->lock);
 
     while (bytes != 0) {
         uint64_t copy_offset = 0;
         QCow2SubclusterType type;
         /* prepare next request */
         cur_bytes = MIN(bytes, INT_MAX);
         cur_write_flags = write_flags;
 
         ret = qcow2_get_host_offset(bs, src_offset, &cur_bytes,
                                     &copy_offset, &type);
         if (ret < 0) {
             goto out;
         }
 
         switch (type) {
         case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
         case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
             if (bs->backing && bs->backing->bs) {
                 int64_t backing_length = bdrv_getlength(bs->backing->bs);
                 if (src_offset >= backing_length) {
                     cur_write_flags |= BDRV_REQ_ZERO_WRITE;
                 } else {
                     child = bs->backing;
                     cur_bytes = MIN(cur_bytes, backing_length - src_offset);
                     copy_offset = src_offset;
                 }
             } else {
                 cur_write_flags |= BDRV_REQ_ZERO_WRITE;
             }
             break;
 
         case QCOW2_SUBCLUSTER_ZERO_PLAIN:
         case QCOW2_SUBCLUSTER_ZERO_ALLOC:
             cur_write_flags |= BDRV_REQ_ZERO_WRITE;
             break;
 
         case QCOW2_SUBCLUSTER_COMPRESSED:
             ret = -ENOTSUP;
             goto out;
 
         case QCOW2_SUBCLUSTER_NORMAL:
             child = s->data_file;
             break;
 
         default:
             abort();
         }
         qemu_co_mutex_unlock(&s->lock);
         ret = bdrv_co_copy_range_from(child,
                                       copy_offset,
                                       dst, dst_offset,
                                       cur_bytes, read_flags, cur_write_flags);
         qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {
             goto out;
         }
 
         bytes -= cur_bytes;
         src_offset += cur_bytes;
         dst_offset += cur_bytes;
     }
     ret = 0;
 
 out:
     qemu_co_mutex_unlock(&s->lock);
     return ret;
 }
 
 static int coroutine_fn
 qcow2_co_copy_range_to(BlockDriverState *bs,
                        BdrvChild *src, int64_t src_offset,
                        BdrvChild *dst, int64_t dst_offset,
                        int64_t bytes, BdrvRequestFlags read_flags,
                        BdrvRequestFlags write_flags)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret;
     unsigned int cur_bytes; /* number of sectors in current iteration */
     uint64_t host_offset;
     QCowL2Meta *l2meta = NULL;
 
     assert(!bs->encrypted);
 
     qemu_co_mutex_lock(&s->lock);
 
     while (bytes != 0) {
 
         l2meta = NULL;
 
         cur_bytes = MIN(bytes, INT_MAX);
 
         /* TODO:
          * If src->bs == dst->bs, we could simply copy by incrementing
          * the refcnt, without copying user data.
          * Or if src->bs == dst->bs->backing->bs, we could copy by discarding. */
         ret = qcow2_alloc_host_offset(bs, dst_offset, &cur_bytes,
                                       &host_offset, &l2meta);
         if (ret < 0) {
             goto fail;
         }
 
         ret = qcow2_pre_write_overlap_check(bs, 0, host_offset, cur_bytes,
                                             true);
         if (ret < 0) {
             goto fail;
         }
 
         qemu_co_mutex_unlock(&s->lock);
         ret = bdrv_co_copy_range_to(src, src_offset, s->data_file, host_offset,
                                     cur_bytes, read_flags, write_flags);
         qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {
             goto fail;
         }
 
         ret = qcow2_handle_l2meta(bs, &l2meta, true);
         if (ret) {
             goto fail;
         }
 
         bytes -= cur_bytes;
         src_offset += cur_bytes;
         dst_offset += cur_bytes;
     }
     ret = 0;
 
 fail:
     qcow2_handle_l2meta(bs, &l2meta, false);
 
     qemu_co_mutex_unlock(&s->lock);
 
     trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
 
     return ret;
 }
 
 static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
                                           bool exact, PreallocMode prealloc,
                                           BdrvRequestFlags flags, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t old_length;
     int64_t new_l1_size;
     int ret;
     QDict *options;
 
     if (prealloc != PREALLOC_MODE_OFF && prealloc != PREALLOC_MODE_METADATA &&
         prealloc != PREALLOC_MODE_FALLOC && prealloc != PREALLOC_MODE_FULL)
     {
         error_setg(errp, "Unsupported preallocation mode '%s'",
                    PreallocMode_str(prealloc));
         return -ENOTSUP;
     }
 
     if (!QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)) {
         error_setg(errp, "The new size must be a multiple of %u",
                    (unsigned) BDRV_SECTOR_SIZE);
         return -EINVAL;
     }
 
     qemu_co_mutex_lock(&s->lock);
 
     /*
      * Even though we store snapshot size for all images, it was not
      * required until v3, so it is not safe to proceed for v2.
      */
     if (s->nb_snapshots && s->qcow_version < 3) {
         error_setg(errp, "Can't resize a v2 image which has snapshots");
         ret = -ENOTSUP;
         goto fail;
     }
 
     /* See qcow2-bitmap.c for which bitmap scenarios prevent a resize. */
     if (qcow2_truncate_bitmaps_check(bs, errp)) {
         ret = -ENOTSUP;
         goto fail;
     }
 
     old_length = bs->total_sectors * BDRV_SECTOR_SIZE;
     new_l1_size = size_to_l1(s, offset);
 
     if (offset < old_length) {
         int64_t last_cluster, old_file_size;
         if (prealloc != PREALLOC_MODE_OFF) {
             error_setg(errp,
                        "Preallocation can't be used for shrinking an image");
             ret = -EINVAL;
             goto fail;
         }
 
         ret = qcow2_cluster_discard(bs, ROUND_UP(offset, s->cluster_size),
                                     old_length - ROUND_UP(offset,
                                                           s->cluster_size),
                                     QCOW2_DISCARD_ALWAYS, true);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to discard cropped clusters");
             goto fail;
         }
 
         ret = qcow2_shrink_l1_table(bs, new_l1_size);
         if (ret < 0) {
             error_setg_errno(errp, -ret,
                              "Failed to reduce the number of L2 tables");
             goto fail;
         }
 
         ret = qcow2_shrink_reftable(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret,
                              "Failed to discard unused refblocks");
             goto fail;
         }
 
         old_file_size = bdrv_getlength(bs->file->bs);
         if (old_file_size < 0) {
             error_setg_errno(errp, -old_file_size,
                              "Failed to inquire current file length");
             ret = old_file_size;
             goto fail;
         }
         last_cluster = qcow2_get_last_cluster(bs, old_file_size);
         if (last_cluster < 0) {
             error_setg_errno(errp, -last_cluster,
                              "Failed to find the last cluster");
             ret = last_cluster;
             goto fail;
         }
         if ((last_cluster + 1) * s->cluster_size < old_file_size) {
             Error *local_err = NULL;
 
             /*
              * Do not pass @exact here: It will not help the user if
              * we get an error here just because they wanted to shrink
              * their qcow2 image (on a block device) with qemu-img.
              * (And on the qcow2 layer, the @exact requirement is
              * always fulfilled, so there is no need to pass it on.)
              */
             bdrv_co_truncate(bs->file, (last_cluster + 1) * s->cluster_size,
                              false, PREALLOC_MODE_OFF, 0, &local_err);
             if (local_err) {
                 warn_reportf_err(local_err,
                                  "Failed to truncate the tail of the image: ");
             }
         }
     } else {
         ret = qcow2_grow_l1_table(bs, new_l1_size, true);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to grow the L1 table");
             goto fail;
         }
 
         if (data_file_is_raw(bs) && prealloc == PREALLOC_MODE_OFF) {
             /*
              * When creating a qcow2 image with data-file-raw, we enforce
              * at least prealloc=metadata, so that the L1/L2 tables are
              * fully allocated and reading from the data file will return
              * the same data as reading from the qcow2 image.  When the
              * image is grown, we must consequently preallocate the
              * metadata structures to cover the added area.
              */
             prealloc = PREALLOC_MODE_METADATA;
         }
     }
 
     switch (prealloc) {
     case PREALLOC_MODE_OFF:
         if (has_data_file(bs)) {
             /*
              * If the caller wants an exact resize, the external data
              * file should be resized to the exact target size, too,
              * so we pass @exact here.
              */
             ret = bdrv_co_truncate(s->data_file, offset, exact, prealloc, 0,
                                    errp);
             if (ret < 0) {
                 goto fail;
             }
         }
         break;
 
     case PREALLOC_MODE_METADATA:
         ret = preallocate_co(bs, old_length, offset, prealloc, errp);
         if (ret < 0) {
             goto fail;
         }
         break;
 
     case PREALLOC_MODE_FALLOC:
     case PREALLOC_MODE_FULL:
     {
         int64_t allocation_start, host_offset, guest_offset;
         int64_t clusters_allocated;
         int64_t old_file_size, last_cluster, new_file_size;
         uint64_t nb_new_data_clusters, nb_new_l2_tables;
         bool subclusters_need_allocation = false;
 
         /* With a data file, preallocation means just allocating the metadata
          * and forwarding the truncate request to the data file */
         if (has_data_file(bs)) {
             ret = preallocate_co(bs, old_length, offset, prealloc, errp);
             if (ret < 0) {
                 goto fail;
             }
             break;
         }
 
         old_file_size = bdrv_getlength(bs->file->bs);
         if (old_file_size < 0) {
             error_setg_errno(errp, -old_file_size,
                              "Failed to inquire current file length");
             ret = old_file_size;
             goto fail;
         }
 
         last_cluster = qcow2_get_last_cluster(bs, old_file_size);
         if (last_cluster >= 0) {
             old_file_size = (last_cluster + 1) * s->cluster_size;
         } else {
             old_file_size = ROUND_UP(old_file_size, s->cluster_size);
         }
 
         nb_new_data_clusters = (ROUND_UP(offset, s->cluster_size) -
             start_of_cluster(s, old_length)) >> s->cluster_bits;
 
         /* This is an overestimation; we will not actually allocate space for
          * these in the file but just make sure the new refcount structures are
          * able to cover them so we will not have to allocate new refblocks
          * while entering the data blocks in the potentially new L2 tables.
          * (We do not actually care where the L2 tables are placed. Maybe they
          *  are already allocated or they can be placed somewhere before
          *  @old_file_size. It does not matter because they will be fully
          *  allocated automatically, so they do not need to be covered by the
          *  preallocation. All that matters is that we will not have to allocate
          *  new refcount structures for them.) */
         nb_new_l2_tables = DIV_ROUND_UP(nb_new_data_clusters,
                                         s->cluster_size / l2_entry_size(s));
         /* The cluster range may not be aligned to L2 boundaries, so add one L2
          * table for a potential head/tail */
         nb_new_l2_tables++;
 
         allocation_start = qcow2_refcount_area(bs, old_file_size,
                                                nb_new_data_clusters +
                                                nb_new_l2_tables,
                                                true, 0, 0);
         if (allocation_start < 0) {
             error_setg_errno(errp, -allocation_start,
                              "Failed to resize refcount structures");
             ret = allocation_start;
             goto fail;
         }
 
         clusters_allocated = qcow2_alloc_clusters_at(bs, allocation_start,
                                                      nb_new_data_clusters);
         if (clusters_allocated < 0) {
             error_setg_errno(errp, -clusters_allocated,
                              "Failed to allocate data clusters");
             ret = clusters_allocated;
             goto fail;
         }
 
         assert(clusters_allocated == nb_new_data_clusters);
 
         /* Allocate the data area */
         new_file_size = allocation_start +
                         nb_new_data_clusters * s->cluster_size;
         /*
          * Image file grows, so @exact does not matter.
          *
          * If we need to zero out the new area, try first whether the protocol
          * driver can already take care of this.
          */
         if (flags & BDRV_REQ_ZERO_WRITE) {
             ret = bdrv_co_truncate(bs->file, new_file_size, false, prealloc,
                                    BDRV_REQ_ZERO_WRITE, NULL);
             if (ret >= 0) {
                 flags &= ~BDRV_REQ_ZERO_WRITE;
                 /* Ensure that we read zeroes and not backing file data */
                 subclusters_need_allocation = true;
             }
         } else {
             ret = -1;
         }
         if (ret < 0) {
             ret = bdrv_co_truncate(bs->file, new_file_size, false, prealloc, 0,
                                    errp);
         }
         if (ret < 0) {
             error_prepend(errp, "Failed to resize underlying file: ");
             qcow2_free_clusters(bs, allocation_start,
                                 nb_new_data_clusters * s->cluster_size,
                                 QCOW2_DISCARD_OTHER);
             goto fail;
         }
 
         /* Create the necessary L2 entries */
         host_offset = allocation_start;
         guest_offset = old_length;
         while (nb_new_data_clusters) {
             int64_t nb_clusters = MIN(
                 nb_new_data_clusters,
                 s->l2_slice_size - offset_to_l2_slice_index(s, guest_offset));
             unsigned cow_start_length = offset_into_cluster(s, guest_offset);
             QCowL2Meta allocation;
             guest_offset = start_of_cluster(s, guest_offset);
             allocation = (QCowL2Meta) {
                 .offset       = guest_offset,
                 .alloc_offset = host_offset,
                 .nb_clusters  = nb_clusters,
                 .cow_start    = {
                     .offset       = 0,
                     .nb_bytes     = cow_start_length,
                 },
                 .cow_end      = {
                     .offset       = nb_clusters << s->cluster_bits,
                     .nb_bytes     = 0,
                 },
                 .prealloc     = !subclusters_need_allocation,
             };
             qemu_co_queue_init(&allocation.dependent_requests);
 
             ret = qcow2_alloc_cluster_link_l2(bs, &allocation);
             if (ret < 0) {
                 error_setg_errno(errp, -ret, "Failed to update L2 tables");
                 qcow2_free_clusters(bs, host_offset,
                                     nb_new_data_clusters * s->cluster_size,
                                     QCOW2_DISCARD_OTHER);
                 goto fail;
             }
 
             guest_offset += nb_clusters * s->cluster_size;
             host_offset += nb_clusters * s->cluster_size;
             nb_new_data_clusters -= nb_clusters;
         }
         break;
     }
 
     default:
         g_assert_not_reached();
     }
 
     if ((flags & BDRV_REQ_ZERO_WRITE) && offset > old_length) {
         uint64_t zero_start = QEMU_ALIGN_UP(old_length, s->subcluster_size);
 
         /*
          * Use zero clusters as much as we can. qcow2_subcluster_zeroize()
          * requires a subcluster-aligned start. The end may be unaligned if
          * it is at the end of the image (which it is here).
          */
         if (offset > zero_start) {
             ret = qcow2_subcluster_zeroize(bs, zero_start, offset - zero_start,
                                            0);
             if (ret < 0) {
                 error_setg_errno(errp, -ret, "Failed to zero out new clusters");
                 goto fail;
             }
         }
 
         /* Write explicit zeros for the unaligned head */
         if (zero_start > old_length) {
             uint64_t len = MIN(zero_start, offset) - old_length;
             uint8_t *buf = qemu_blockalign0(bs, len);
             QEMUIOVector qiov;
             qemu_iovec_init_buf(&qiov, buf, len);
 
             qemu_co_mutex_unlock(&s->lock);
             ret = qcow2_co_pwritev_part(bs, old_length, len, &qiov, 0, 0);
             qemu_co_mutex_lock(&s->lock);
 
             qemu_vfree(buf);
             if (ret < 0) {
                 error_setg_errno(errp, -ret, "Failed to zero out the new area");
                 goto fail;
             }
         }
     }
 
     if (prealloc != PREALLOC_MODE_OFF) {
         /* Flush metadata before actually changing the image size */
         ret = qcow2_write_caches(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret,
                              "Failed to flush the preallocated area to disk");
             goto fail;
         }
     }
 
     bs->total_sectors = offset / BDRV_SECTOR_SIZE;
 
     /* write updated header.size */
     offset = cpu_to_be64(offset);
     ret = bdrv_co_pwrite_sync(bs->file, offsetof(QCowHeader, size),
                               sizeof(offset), &offset, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to update the image size");
         goto fail;
     }
 
     s->l1_vm_state_index = new_l1_size;
 
     /* Update cache sizes */
     options = qdict_clone_shallow(bs->options);
     ret = qcow2_update_options(bs, options, s->flags, errp);
     qobject_unref(options);
     if (ret < 0) {
         goto fail;
     }
     ret = 0;
 fail:
     qemu_co_mutex_unlock(&s->lock);
     return ret;
 }
 
 static coroutine_fn int
 qcow2_co_pwritev_compressed_task(BlockDriverState *bs,
                                  uint64_t offset, uint64_t bytes,
                                  QEMUIOVector *qiov, size_t qiov_offset)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret;
     ssize_t out_len;
     uint8_t *buf, *out_buf;
     uint64_t cluster_offset;
 
     assert(bytes == s->cluster_size || (bytes < s->cluster_size &&
            (offset + bytes == bs->total_sectors << BDRV_SECTOR_BITS)));
 
     buf = qemu_blockalign(bs, s->cluster_size);
     if (bytes < s->cluster_size) {
         /* Zero-pad last write if image size is not cluster aligned */
         memset(buf + bytes, 0, s->cluster_size - bytes);
     }
     qemu_iovec_to_buf(qiov, qiov_offset, buf, bytes);
 
     out_buf = g_malloc(s->cluster_size);
 
     out_len = qcow2_co_compress(bs, out_buf, s->cluster_size - 1,
                                 buf, s->cluster_size);
     if (out_len == -ENOMEM) {
         /* could not compress: write normal cluster */
         ret = qcow2_co_pwritev_part(bs, offset, bytes, qiov, qiov_offset, 0);
         if (ret < 0) {
             goto fail;
         }
         goto success;
     } else if (out_len < 0) {
         ret = -EINVAL;
         goto fail;
     }
 
     qemu_co_mutex_lock(&s->lock);
     ret = qcow2_alloc_compressed_cluster_offset(bs, offset, out_len,
                                                 &cluster_offset);
     if (ret < 0) {
         qemu_co_mutex_unlock(&s->lock);
         goto fail;
     }
 
     ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len, true);
     qemu_co_mutex_unlock(&s->lock);
     if (ret < 0) {
         goto fail;
     }
 
     BLKDBG_EVENT(s->data_file, BLKDBG_WRITE_COMPRESSED);
     ret = bdrv_co_pwrite(s->data_file, cluster_offset, out_len, out_buf, 0);
     if (ret < 0) {
         goto fail;
     }
 success:
     ret = 0;
 fail:
     qemu_vfree(buf);
     g_free(out_buf);
     return ret;
 }
 
 static coroutine_fn int qcow2_co_pwritev_compressed_task_entry(AioTask *task)
 {
     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
 
     assert(!t->subcluster_type && !t->l2meta);
 
     return qcow2_co_pwritev_compressed_task(t->bs, t->offset, t->bytes, t->qiov,
                                             t->qiov_offset);
 }
 
 /*
  * XXX: put compressed sectors first, then all the cluster aligned
  * tables to avoid losing bytes in alignment
  */
 static coroutine_fn int
 qcow2_co_pwritev_compressed_part(BlockDriverState *bs,
                                  int64_t offset, int64_t bytes,
                                  QEMUIOVector *qiov, size_t qiov_offset)
 {
     BDRVQcow2State *s = bs->opaque;
     AioTaskPool *aio = NULL;
     int ret = 0;
 
     if (has_data_file(bs)) {
         return -ENOTSUP;
     }
 
     if (bytes == 0) {
         /*
          * align end of file to a sector boundary to ease reading with
          * sector based I/Os
          */
         int64_t len = bdrv_getlength(bs->file->bs);
         if (len < 0) {
             return len;
         }
         return bdrv_co_truncate(bs->file, len, false, PREALLOC_MODE_OFF, 0,
                                 NULL);
     }
 
     if (offset_into_cluster(s, offset)) {
         return -EINVAL;
     }
 
     if (offset_into_cluster(s, bytes) &&
         (offset + bytes) != (bs->total_sectors << BDRV_SECTOR_BITS)) {
         return -EINVAL;
     }
 
     while (bytes && aio_task_pool_status(aio) == 0) {
         uint64_t chunk_size = MIN(bytes, s->cluster_size);
 
         if (!aio && chunk_size != bytes) {
             aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
         }
 
         ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_compressed_task_entry,
                              0, 0, offset, chunk_size, qiov, qiov_offset, NULL);
         if (ret < 0) {
             break;
         }
         qiov_offset += chunk_size;
         offset += chunk_size;
         bytes -= chunk_size;
     }
 
     if (aio) {
         aio_task_pool_wait_all(aio);
         if (ret == 0) {
             ret = aio_task_pool_status(aio);
         }
         g_free(aio);
     }
 
     return ret;
 }
 
 static int coroutine_fn
 qcow2_co_preadv_compressed(BlockDriverState *bs,
                            uint64_t l2_entry,
                            uint64_t offset,
                            uint64_t bytes,
                            QEMUIOVector *qiov,
                            size_t qiov_offset)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret = 0, csize;
     uint64_t coffset;
     uint8_t *buf, *out_buf;
     int offset_in_cluster = offset_into_cluster(s, offset);
 
     qcow2_parse_compressed_l2_entry(bs, l2_entry, &coffset, &csize);
 
     buf = g_try_malloc(csize);
     if (!buf) {
         return -ENOMEM;
     }
 
     out_buf = qemu_blockalign(bs, s->cluster_size);
 
     BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
     ret = bdrv_co_pread(bs->file, coffset, csize, buf, 0);
     if (ret < 0) {
         goto fail;
     }
 
     if (qcow2_co_decompress(bs, out_buf, s->cluster_size, buf, csize) < 0) {
         ret = -EIO;
         goto fail;
     }
 
     qemu_iovec_from_buf(qiov, qiov_offset, out_buf + offset_in_cluster, bytes);
 
 fail:
     qemu_vfree(out_buf);
     g_free(buf);
 
     return ret;
 }
 
 static int make_completely_empty(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     Error *local_err = NULL;
     int ret, l1_clusters;
     int64_t offset;
     uint64_t *new_reftable = NULL;
     uint64_t rt_entry, l1_size2;
     struct {
         uint64_t l1_offset;
         uint64_t reftable_offset;
         uint32_t reftable_clusters;
     } QEMU_PACKED l1_ofs_rt_ofs_cls;
 
     ret = qcow2_cache_empty(bs, s->l2_table_cache);
     if (ret < 0) {
         goto fail;
     }
 
     ret = qcow2_cache_empty(bs, s->refcount_block_cache);
     if (ret < 0) {
         goto fail;
     }
 
     /* Refcounts will be broken utterly */
     ret = qcow2_mark_dirty(bs);
     if (ret < 0) {
         goto fail;
     }
 
     BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
 
     l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / L1E_SIZE);
     l1_size2 = (uint64_t)s->l1_size * L1E_SIZE;
 
     /* After this call, neither the in-memory nor the on-disk refcount
      * information accurately describe the actual references */
 
     ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset,
                              l1_clusters * s->cluster_size, 0);
     if (ret < 0) {
         goto fail_broken_refcounts;
     }
     memset(s->l1_table, 0, l1_size2);
 
     BLKDBG_EVENT(bs->file, BLKDBG_EMPTY_IMAGE_PREPARE);
 
     /* Overwrite enough clusters at the beginning of the sectors to place
      * the refcount table, a refcount block and the L1 table in; this may
      * overwrite parts of the existing refcount and L1 table, which is not
      * an issue because the dirty flag is set, complete data loss is in fact
      * desired and partial data loss is consequently fine as well */
     ret = bdrv_pwrite_zeroes(bs->file, s->cluster_size,
                              (2 + l1_clusters) * s->cluster_size, 0);
     /* This call (even if it failed overall) may have overwritten on-disk
      * refcount structures; in that case, the in-memory refcount information
      * will probably differ from the on-disk information which makes the BDS
      * unusable */
     if (ret < 0) {
         goto fail_broken_refcounts;
     }
 
     BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
     BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_UPDATE);
 
     /* "Create" an empty reftable (one cluster) directly after the image
      * header and an empty L1 table three clusters after the image header;
      * the cluster between those two will be used as the first refblock */
     l1_ofs_rt_ofs_cls.l1_offset = cpu_to_be64(3 * s->cluster_size);
     l1_ofs_rt_ofs_cls.reftable_offset = cpu_to_be64(s->cluster_size);
     l1_ofs_rt_ofs_cls.reftable_clusters = cpu_to_be32(1);
     ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_table_offset),
                            sizeof(l1_ofs_rt_ofs_cls), &l1_ofs_rt_ofs_cls, 0);
     if (ret < 0) {
         goto fail_broken_refcounts;
     }
 
     s->l1_table_offset = 3 * s->cluster_size;
 
     new_reftable = g_try_new0(uint64_t, s->cluster_size / REFTABLE_ENTRY_SIZE);
     if (!new_reftable) {
         ret = -ENOMEM;
         goto fail_broken_refcounts;
     }
 
     s->refcount_table_offset = s->cluster_size;
     s->refcount_table_size   = s->cluster_size / REFTABLE_ENTRY_SIZE;
     s->max_refcount_table_index = 0;
 
     g_free(s->refcount_table);
     s->refcount_table = new_reftable;
     new_reftable = NULL;
 
     /* Now the in-memory refcount information again corresponds to the on-disk
      * information (reftable is empty and no refblocks (the refblock cache is
      * empty)); however, this means some clusters (e.g. the image header) are
      * referenced, but not refcounted, but the normal qcow2 code assumes that
      * the in-memory information is always correct */
 
     BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
 
     /* Enter the first refblock into the reftable */
     rt_entry = cpu_to_be64(2 * s->cluster_size);
     ret = bdrv_pwrite_sync(bs->file, s->cluster_size, sizeof(rt_entry),
                            &rt_entry, 0);
     if (ret < 0) {
         goto fail_broken_refcounts;
     }
     s->refcount_table[0] = 2 * s->cluster_size;
 
     s->free_cluster_index = 0;
     assert(3 + l1_clusters <= s->refcount_block_size);
     offset = qcow2_alloc_clusters(bs, 3 * s->cluster_size + l1_size2);
     if (offset < 0) {
         ret = offset;
         goto fail_broken_refcounts;
     } else if (offset > 0) {
         error_report("First cluster in emptied image is in use");
         abort();
     }
 
     /* Now finally the in-memory information corresponds to the on-disk
      * structures and is correct */
     ret = qcow2_mark_clean(bs);
     if (ret < 0) {
         goto fail;
     }
 
     ret = bdrv_truncate(bs->file, (3 + l1_clusters) * s->cluster_size, false,
                         PREALLOC_MODE_OFF, 0, &local_err);
     if (ret < 0) {
         error_report_err(local_err);
         goto fail;
     }
 
     return 0;
 
 fail_broken_refcounts:
     /* The BDS is unusable at this point. If we wanted to make it usable, we
      * would have to call qcow2_refcount_close(), qcow2_refcount_init(),
      * qcow2_check_refcounts(), qcow2_refcount_close() and qcow2_refcount_init()
      * again. However, because the functions which could have caused this error
      * path to be taken are used by those functions as well, it's very likely
      * that that sequence will fail as well. Therefore, just eject the BDS. */
     bs->drv = NULL;
 
 fail:
     g_free(new_reftable);
     return ret;
 }
 
 static int qcow2_make_empty(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t offset, end_offset;
     int step = QEMU_ALIGN_DOWN(INT_MAX, s->cluster_size);
     int l1_clusters, ret = 0;
 
     l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / L1E_SIZE);
 
     if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps &&
         3 + l1_clusters <= s->refcount_block_size &&
         s->crypt_method_header != QCOW_CRYPT_LUKS &&
         !has_data_file(bs)) {
         /* The following function only works for qcow2 v3 images (it
          * requires the dirty flag) and only as long as there are no
          * features that reserve extra clusters (such as snapshots,
          * LUKS header, or persistent bitmaps), because it completely
          * empties the image.  Furthermore, the L1 table and three
          * additional clusters (image header, refcount table, one
          * refcount block) have to fit inside one refcount block. It
          * only resets the image file, i.e. does not work with an
          * external data file. */
         return make_completely_empty(bs);
     }
 
     /* This fallback code simply discards every active cluster; this is slow,
      * but works in all cases */
     end_offset = bs->total_sectors * BDRV_SECTOR_SIZE;
     for (offset = 0; offset < end_offset; offset += step) {
         /* As this function is generally used after committing an external
          * snapshot, QCOW2_DISCARD_SNAPSHOT seems appropriate. Also, the
          * default action for this kind of discard is to pass the discard,
          * which will ideally result in an actually smaller image file, as
          * is probably desired. */
         ret = qcow2_cluster_discard(bs, offset, MIN(step, end_offset - offset),
                                     QCOW2_DISCARD_SNAPSHOT, true);
         if (ret < 0) {
             break;
         }
     }
 
     return ret;
 }
 
 static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     int ret;
 
     qemu_co_mutex_lock(&s->lock);
     ret = qcow2_write_caches(bs);
     qemu_co_mutex_unlock(&s->lock);
 
     return ret;
 }
 
 static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs,
                                        Error **errp)
 {
     Error *local_err = NULL;
     BlockMeasureInfo *info;
     uint64_t required = 0; /* bytes that contribute to required size */
     uint64_t virtual_size; /* disk size as seen by guest */
     uint64_t refcount_bits;
     uint64_t l2_tables;
     uint64_t luks_payload_size = 0;
     size_t cluster_size;
     int version;
     char *optstr;
     PreallocMode prealloc;
     bool has_backing_file;
     bool has_luks;
     bool extended_l2;
     size_t l2e_size;
 
     /* Parse image creation options */
     extended_l2 = qemu_opt_get_bool_del(opts, BLOCK_OPT_EXTL2, false);
 
     cluster_size = qcow2_opt_get_cluster_size_del(opts, extended_l2,
                                                   &local_err);
     if (local_err) {
         goto err;
     }
 
     version = qcow2_opt_get_version_del(opts, &local_err);
     if (local_err) {
         goto err;
     }
 
     refcount_bits = qcow2_opt_get_refcount_bits_del(opts, version, &local_err);
     if (local_err) {
         goto err;
     }
 
     optstr = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
     prealloc = qapi_enum_parse(&PreallocMode_lookup, optstr,
                                PREALLOC_MODE_OFF, &local_err);
     g_free(optstr);
     if (local_err) {
         goto err;
     }
 
     optstr = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
     has_backing_file = !!optstr;
     g_free(optstr);
 
     optstr = qemu_opt_get_del(opts, BLOCK_OPT_ENCRYPT_FORMAT);
     has_luks = optstr && strcmp(optstr, "luks") == 0;
     g_free(optstr);
 
     if (has_luks) {
         g_autoptr(QCryptoBlockCreateOptions) create_opts = NULL;
         QDict *cryptoopts = qcow2_extract_crypto_opts(opts, "luks", errp);
         size_t headerlen;
 
         create_opts = block_crypto_create_opts_init(cryptoopts, errp);
         qobject_unref(cryptoopts);
         if (!create_opts) {
             goto err;
         }
 
         if (!qcrypto_block_calculate_payload_offset(create_opts,
                                                     "encrypt.",
                                                     &headerlen,
                                                     &local_err)) {
             goto err;
         }
 
         luks_payload_size = ROUND_UP(headerlen, cluster_size);
     }
 
     virtual_size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
     virtual_size = ROUND_UP(virtual_size, cluster_size);
 
     /* Check that virtual disk size is valid */
     l2e_size = extended_l2 ? L2E_SIZE_EXTENDED : L2E_SIZE_NORMAL;
     l2_tables = DIV_ROUND_UP(virtual_size / cluster_size,
                              cluster_size / l2e_size);
     if (l2_tables * L1E_SIZE > QCOW_MAX_L1_SIZE) {
         error_setg(&local_err, "The image size is too large "
                                "(try using a larger cluster size)");
         goto err;
     }
 
     /* Account for input image */
     if (in_bs) {
         int64_t ssize = bdrv_getlength(in_bs);
         if (ssize < 0) {
             error_setg_errno(&local_err, -ssize,
                              "Unable to get image virtual_size");
             goto err;
         }
 
         virtual_size = ROUND_UP(ssize, cluster_size);
 
         if (has_backing_file) {
             /* We don't how much of the backing chain is shared by the input
              * image and the new image file.  In the worst case the new image's
              * backing file has nothing in common with the input image.  Be
              * conservative and assume all clusters need to be written.
              */
             required = virtual_size;
         } else {
             int64_t offset;
             int64_t pnum = 0;
 
             for (offset = 0; offset < ssize; offset += pnum) {
                 int ret;
 
                 ret = bdrv_block_status_above(in_bs, NULL, offset,
                                               ssize - offset, &pnum, NULL,
                                               NULL);
                 if (ret < 0) {
                     error_setg_errno(&local_err, -ret,
                                      "Unable to get block status");
                     goto err;
                 }
 
                 if (ret & BDRV_BLOCK_ZERO) {
                     /* Skip zero regions (safe with no backing file) */
                 } else if ((ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED)) ==
                            (BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED)) {
                     /* Extend pnum to end of cluster for next iteration */
                     pnum = ROUND_UP(offset + pnum, cluster_size) - offset;
 
                     /* Count clusters we've seen */
                     required += offset % cluster_size + pnum;
                 }
             }
         }
     }
 
     /* Take into account preallocation.  Nothing special is needed for
      * PREALLOC_MODE_METADATA since metadata is always counted.
      */
     if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) {
         required = virtual_size;
     }
 
     info = g_new0(BlockMeasureInfo, 1);
     info->fully_allocated = luks_payload_size +
         qcow2_calc_prealloc_size(virtual_size, cluster_size,
                                  ctz32(refcount_bits), extended_l2);
 
     /*
      * Remove data clusters that are not required.  This overestimates the
      * required size because metadata needed for the fully allocated file is
      * still counted.  Show bitmaps only if both source and destination
      * would support them.
      */
     info->required = info->fully_allocated - virtual_size + required;
     info->has_bitmaps = version >= 3 && in_bs &&
         bdrv_supports_persistent_dirty_bitmap(in_bs);
     if (info->has_bitmaps) {
         info->bitmaps = qcow2_get_persistent_dirty_bitmap_size(in_bs,
                                                                cluster_size);
     }
     return info;
 
 err:
     error_propagate(errp, local_err);
     return NULL;
 }
 
 static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BDRVQcow2State *s = bs->opaque;
     bdi->cluster_size = s->cluster_size;
     bdi->vm_state_offset = qcow2_vm_state_offset(s);
     bdi->is_dirty = s->incompatible_features & QCOW2_INCOMPAT_DIRTY;
     return 0;
 }
 
 static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs,
                                                   Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     ImageInfoSpecific *spec_info;
     QCryptoBlockInfo *encrypt_info = NULL;
 
     if (s->crypto != NULL) {
         encrypt_info = qcrypto_block_get_info(s->crypto, errp);
         if (!encrypt_info) {
             return NULL;
         }
     }
 
     spec_info = g_new(ImageInfoSpecific, 1);
     *spec_info = (ImageInfoSpecific){
         .type  = IMAGE_INFO_SPECIFIC_KIND_QCOW2,
         .u.qcow2.data = g_new0(ImageInfoSpecificQCow2, 1),
     };
     if (s->qcow_version == 2) {
         *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
             .compat             = g_strdup("0.10"),
             .refcount_bits      = s->refcount_bits,
         };
     } else if (s->qcow_version == 3) {
         Qcow2BitmapInfoList *bitmaps;
         if (!qcow2_get_bitmap_info_list(bs, &bitmaps, errp)) {
             qapi_free_ImageInfoSpecific(spec_info);
             qapi_free_QCryptoBlockInfo(encrypt_info);
             return NULL;
         }
         *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
             .compat             = g_strdup("1.1"),
             .lazy_refcounts     = s->compatible_features &
                                   QCOW2_COMPAT_LAZY_REFCOUNTS,
             .has_lazy_refcounts = true,
             .corrupt            = s->incompatible_features &
                                   QCOW2_INCOMPAT_CORRUPT,
             .has_corrupt        = true,
             .has_extended_l2    = true,
             .extended_l2        = has_subclusters(s),
             .refcount_bits      = s->refcount_bits,
             .has_bitmaps        = !!bitmaps,
             .bitmaps            = bitmaps,
             .has_data_file      = !!s->image_data_file,
             .data_file          = g_strdup(s->image_data_file),
             .has_data_file_raw  = has_data_file(bs),
             .data_file_raw      = data_file_is_raw(bs),
             .compression_type   = s->compression_type,
         };
     } else {
         /* if this assertion fails, this probably means a new version was
          * added without having it covered here */
         assert(false);
     }
 
     if (encrypt_info) {
         ImageInfoSpecificQCow2Encryption *qencrypt =
             g_new(ImageInfoSpecificQCow2Encryption, 1);
         switch (encrypt_info->format) {
         case Q_CRYPTO_BLOCK_FORMAT_QCOW:
             qencrypt->format = BLOCKDEV_QCOW2_ENCRYPTION_FORMAT_AES;
             break;
         case Q_CRYPTO_BLOCK_FORMAT_LUKS:
             qencrypt->format = BLOCKDEV_QCOW2_ENCRYPTION_FORMAT_LUKS;
             qencrypt->u.luks = encrypt_info->u.luks;
             break;
         default:
             abort();
         }
         /* Since we did shallow copy above, erase any pointers
          * in the original info */
         memset(&encrypt_info->u, 0, sizeof(encrypt_info->u));
         qapi_free_QCryptoBlockInfo(encrypt_info);
 
         spec_info->u.qcow2.data->has_encrypt = true;
         spec_info->u.qcow2.data->encrypt = qencrypt;
     }
 
     return spec_info;
 }
 
 static int qcow2_has_zero_init(BlockDriverState *bs)
 {
     BDRVQcow2State *s = bs->opaque;
     bool preallocated;
 
     if (qemu_in_coroutine()) {
         qemu_co_mutex_lock(&s->lock);
     }
     /*
      * Check preallocation status: Preallocated images have all L2
      * tables allocated, nonpreallocated images have none.  It is
      * therefore enough to check the first one.
      */
     preallocated = s->l1_size > 0 && s->l1_table[0] != 0;
     if (qemu_in_coroutine()) {
         qemu_co_mutex_unlock(&s->lock);
     }
 
     if (!preallocated) {
         return 1;
     } else if (bs->encrypted) {
         return 0;
     } else {
         return bdrv_has_zero_init(s->data_file->bs);
     }
 }
 
 /*
  * Check the request to vmstate. On success return
  *      qcow2_vm_state_offset(bs) + @pos
  */
 static int64_t qcow2_check_vmstate_request(BlockDriverState *bs,
                                            QEMUIOVector *qiov, int64_t pos)
 {
     BDRVQcow2State *s = bs->opaque;
     int64_t vmstate_offset = qcow2_vm_state_offset(s);
     int ret;
 
     /* Incoming requests must be OK */
     bdrv_check_qiov_request(pos, qiov->size, qiov, 0, &error_abort);
 
     if (INT64_MAX - pos < vmstate_offset) {
         return -EIO;
     }
 
     pos += vmstate_offset;
     ret = bdrv_check_qiov_request(pos, qiov->size, qiov, 0, NULL);
     if (ret < 0) {
         return ret;
     }
 
     return pos;
 }
 
 static coroutine_fn int qcow2_save_vmstate(BlockDriverState *bs,
                                            QEMUIOVector *qiov, int64_t pos)
 {
     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
     if (offset < 0) {
         return offset;
     }
 
     BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
     return bs->drv->bdrv_co_pwritev_part(bs, offset, qiov->size, qiov, 0, 0);
 }
 
 static coroutine_fn int qcow2_load_vmstate(BlockDriverState *bs,
                                            QEMUIOVector *qiov, int64_t pos)
 {
     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
     if (offset < 0) {
         return offset;
     }
 
     BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
     return bs->drv->bdrv_co_preadv_part(bs, offset, qiov->size, qiov, 0, 0);
 }
 
 static int qcow2_has_compressed_clusters(BlockDriverState *bs)
 {
     int64_t offset = 0;
     int64_t bytes = bdrv_getlength(bs);
 
     if (bytes < 0) {
         return bytes;
     }
 
     while (bytes != 0) {
         int ret;
         QCow2SubclusterType type;
         unsigned int cur_bytes = MIN(INT_MAX, bytes);
         uint64_t host_offset;
 
         ret = qcow2_get_host_offset(bs, offset, &cur_bytes, &host_offset,
                                     &type);
         if (ret < 0) {
             return ret;
         }
 
         if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
             return 1;
         }
 
         offset += cur_bytes;
         bytes -= cur_bytes;
     }
 
     return 0;
 }
 
 /*
  * Downgrades an image's version. To achieve this, any incompatible features
  * have to be removed.
  */
 static int qcow2_downgrade(BlockDriverState *bs, int target_version,
                            BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
                            Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     int current_version = s->qcow_version;
     int ret;
     int i;
 
     /* This is qcow2_downgrade(), not qcow2_upgrade() */
     assert(target_version < current_version);
 
     /* There are no other versions (now) that you can downgrade to */
     assert(target_version == 2);
 
     if (s->refcount_order != 4) {
         error_setg(errp, "compat=0.10 requires refcount_bits=16");
         return -ENOTSUP;
     }
 
     if (has_data_file(bs)) {
         error_setg(errp, "Cannot downgrade an image with a data file");
         return -ENOTSUP;
     }
 
     /*
      * If any internal snapshot has a different size than the current
      * image size, or VM state size that exceeds 32 bits, downgrading
      * is unsafe.  Even though we would still use v3-compliant output
      * to preserve that data, other v2 programs might not realize
      * those optional fields are important.
      */
     for (i = 0; i < s->nb_snapshots; i++) {
         if (s->snapshots[i].vm_state_size > UINT32_MAX ||
             s->snapshots[i].disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
             error_setg(errp, "Internal snapshots prevent downgrade of image");
             return -ENOTSUP;
         }
     }
 
     /* clear incompatible features */
     if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
         ret = qcow2_mark_clean(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to make the image clean");
             return ret;
         }
     }
 
     /* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
      * the first place; if that happens nonetheless, returning -ENOTSUP is the
      * best thing to do anyway */
 
     if (s->incompatible_features & ~QCOW2_INCOMPAT_COMPRESSION) {
         error_setg(errp, "Cannot downgrade an image with incompatible features "
                    "0x%" PRIx64 " set",
                    s->incompatible_features & ~QCOW2_INCOMPAT_COMPRESSION);
         return -ENOTSUP;
     }
 
     /* since we can ignore compatible features, we can set them to 0 as well */
     s->compatible_features = 0;
     /* if lazy refcounts have been used, they have already been fixed through
      * clearing the dirty flag */
 
     /* clearing autoclear features is trivial */
     s->autoclear_features = 0;
 
     ret = qcow2_expand_zero_clusters(bs, status_cb, cb_opaque);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to turn zero into data clusters");
         return ret;
     }
 
     if (s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION) {
         ret = qcow2_has_compressed_clusters(bs);
         if (ret < 0) {
             error_setg(errp, "Failed to check block status");
             return -EINVAL;
         }
         if (ret) {
             error_setg(errp, "Cannot downgrade an image with zstd compression "
                        "type and existing compressed clusters");
             return -ENOTSUP;
         }
         /*
          * No compressed clusters for now, so just chose default zlib
          * compression.
          */
         s->incompatible_features &= ~QCOW2_INCOMPAT_COMPRESSION;
         s->compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
     }
 
     assert(s->incompatible_features == 0);
 
     s->qcow_version = target_version;
     ret = qcow2_update_header(bs);
     if (ret < 0) {
         s->qcow_version = current_version;
         error_setg_errno(errp, -ret, "Failed to update the image header");
         return ret;
     }
     return 0;
 }
 
 /*
  * Upgrades an image's version.  While newer versions encompass all
  * features of older versions, some things may have to be presented
  * differently.
  */
 static int qcow2_upgrade(BlockDriverState *bs, int target_version,
                          BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
                          Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     bool need_snapshot_update;
     int current_version = s->qcow_version;
     int i;
     int ret;
 
     /* This is qcow2_upgrade(), not qcow2_downgrade() */
     assert(target_version > current_version);
 
     /* There are no other versions (yet) that you can upgrade to */
     assert(target_version == 3);
 
     status_cb(bs, 0, 2, cb_opaque);
 
     /*
      * In v2, snapshots do not need to have extra data.  v3 requires
      * the 64-bit VM state size and the virtual disk size to be
      * present.
      * qcow2_write_snapshots() will always write the list in the
      * v3-compliant format.
      */
     need_snapshot_update = false;
     for (i = 0; i < s->nb_snapshots; i++) {
         if (s->snapshots[i].extra_data_size <
             sizeof_field(QCowSnapshotExtraData, vm_state_size_large) +
             sizeof_field(QCowSnapshotExtraData, disk_size))
         {
             need_snapshot_update = true;
             break;
         }
     }
     if (need_snapshot_update) {
         ret = qcow2_write_snapshots(bs);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to update the snapshot table");
             return ret;
         }
     }
     status_cb(bs, 1, 2, cb_opaque);
 
     s->qcow_version = target_version;
     ret = qcow2_update_header(bs);
     if (ret < 0) {
         s->qcow_version = current_version;
         error_setg_errno(errp, -ret, "Failed to update the image header");
         return ret;
     }
     status_cb(bs, 2, 2, cb_opaque);
 
     return 0;
 }
 
 typedef enum Qcow2AmendOperation {
     /* This is the value Qcow2AmendHelperCBInfo::last_operation will be
      * statically initialized to so that the helper CB can discern the first
      * invocation from an operation change */
     QCOW2_NO_OPERATION = 0,
 
     QCOW2_UPGRADING,
     QCOW2_UPDATING_ENCRYPTION,
     QCOW2_CHANGING_REFCOUNT_ORDER,
     QCOW2_DOWNGRADING,
 } Qcow2AmendOperation;
 
 typedef struct Qcow2AmendHelperCBInfo {
     /* The code coordinating the amend operations should only modify
      * these four fields; the rest will be managed by the CB */
     BlockDriverAmendStatusCB *original_status_cb;
     void *original_cb_opaque;
 
     Qcow2AmendOperation current_operation;
 
     /* Total number of operations to perform (only set once) */
     int total_operations;
 
     /* The following fields are managed by the CB */
 
     /* Number of operations completed */
     int operations_completed;
 
     /* Cumulative offset of all completed operations */
     int64_t offset_completed;
 
     Qcow2AmendOperation last_operation;
     int64_t last_work_size;
 } Qcow2AmendHelperCBInfo;
 
 static void qcow2_amend_helper_cb(BlockDriverState *bs,
                                   int64_t operation_offset,
                                   int64_t operation_work_size, void *opaque)
 {
     Qcow2AmendHelperCBInfo *info = opaque;
     int64_t current_work_size;
     int64_t projected_work_size;
 
     if (info->current_operation != info->last_operation) {
         if (info->last_operation != QCOW2_NO_OPERATION) {
             info->offset_completed += info->last_work_size;
             info->operations_completed++;
         }
 
         info->last_operation = info->current_operation;
     }
 
     assert(info->total_operations > 0);
     assert(info->operations_completed < info->total_operations);
 
     info->last_work_size = operation_work_size;
 
     current_work_size = info->offset_completed + operation_work_size;
 
     /* current_work_size is the total work size for (operations_completed + 1)
      * operations (which includes this one), so multiply it by the number of
      * operations not covered and divide it by the number of operations
      * covered to get a projection for the operations not covered */
     projected_work_size = current_work_size * (info->total_operations -
                                                info->operations_completed - 1)
                                             / (info->operations_completed + 1);
 
     info->original_status_cb(bs, info->offset_completed + operation_offset,
                              current_work_size + projected_work_size,
                              info->original_cb_opaque);
 }
 
 static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
                                BlockDriverAmendStatusCB *status_cb,
                                void *cb_opaque,
                                bool force,
                                Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     int old_version = s->qcow_version, new_version = old_version;
     uint64_t new_size = 0;
     const char *backing_file = NULL, *backing_format = NULL, *data_file = NULL;
     bool lazy_refcounts = s->use_lazy_refcounts;
     bool data_file_raw = data_file_is_raw(bs);
     const char *compat = NULL;
     int refcount_bits = s->refcount_bits;
     int ret;
     QemuOptDesc *desc = opts->list->desc;
     Qcow2AmendHelperCBInfo helper_cb_info;
     bool encryption_update = false;
 
     while (desc && desc->name) {
         if (!qemu_opt_find(opts, desc->name)) {
             /* only change explicitly defined options */
             desc++;
             continue;
         }
 
         if (!strcmp(desc->name, BLOCK_OPT_COMPAT_LEVEL)) {
             compat = qemu_opt_get(opts, BLOCK_OPT_COMPAT_LEVEL);
             if (!compat) {
                 /* preserve default */
             } else if (!strcmp(compat, "0.10") || !strcmp(compat, "v2")) {
                 new_version = 2;
             } else if (!strcmp(compat, "1.1") || !strcmp(compat, "v3")) {
                 new_version = 3;
             } else {
                 error_setg(errp, "Unknown compatibility level %s", compat);
                 return -EINVAL;
             }
         } else if (!strcmp(desc->name, BLOCK_OPT_SIZE)) {
             new_size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 0);
         } else if (!strcmp(desc->name, BLOCK_OPT_BACKING_FILE)) {
             backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
         } else if (!strcmp(desc->name, BLOCK_OPT_BACKING_FMT)) {
             backing_format = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
         } else if (g_str_has_prefix(desc->name, "encrypt.")) {
             if (!s->crypto) {
                 error_setg(errp,
                            "Can't amend encryption options - encryption not present");
                 return -EINVAL;
             }
             if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
                 error_setg(errp,
                            "Only LUKS encryption options can be amended");
                 return -ENOTSUP;
             }
             encryption_update = true;
         } else if (!strcmp(desc->name, BLOCK_OPT_LAZY_REFCOUNTS)) {
             lazy_refcounts = qemu_opt_get_bool(opts, BLOCK_OPT_LAZY_REFCOUNTS,
                                                lazy_refcounts);
         } else if (!strcmp(desc->name, BLOCK_OPT_REFCOUNT_BITS)) {
             refcount_bits = qemu_opt_get_number(opts, BLOCK_OPT_REFCOUNT_BITS,
                                                 refcount_bits);
 
             if (refcount_bits <= 0 || refcount_bits > 64 ||
                 !is_power_of_2(refcount_bits))
             {
                 error_setg(errp, "Refcount width must be a power of two and "
                            "may not exceed 64 bits");
                 return -EINVAL;
             }
         } else if (!strcmp(desc->name, BLOCK_OPT_DATA_FILE)) {
             data_file = qemu_opt_get(opts, BLOCK_OPT_DATA_FILE);
             if (data_file && !has_data_file(bs)) {
                 error_setg(errp, "data-file can only be set for images that "
                                  "use an external data file");
                 return -EINVAL;
             }
         } else if (!strcmp(desc->name, BLOCK_OPT_DATA_FILE_RAW)) {
             data_file_raw = qemu_opt_get_bool(opts, BLOCK_OPT_DATA_FILE_RAW,
                                               data_file_raw);
             if (data_file_raw && !data_file_is_raw(bs)) {
                 error_setg(errp, "data-file-raw cannot be set on existing "
                                  "images");
                 return -EINVAL;
             }
         } else {
             /* if this point is reached, this probably means a new option was
              * added without having it covered here */
             abort();
         }
 
         desc++;
     }
 
     helper_cb_info = (Qcow2AmendHelperCBInfo){
         .original_status_cb = status_cb,
         .original_cb_opaque = cb_opaque,
         .total_operations = (new_version != old_version)
                           + (s->refcount_bits != refcount_bits) +
                             (encryption_update == true)
     };
 
     /* Upgrade first (some features may require compat=1.1) */
     if (new_version > old_version) {
         helper_cb_info.current_operation = QCOW2_UPGRADING;
         ret = qcow2_upgrade(bs, new_version, &qcow2_amend_helper_cb,
                             &helper_cb_info, errp);
         if (ret < 0) {
             return ret;
         }
     }
 
     if (encryption_update) {
         QDict *amend_opts_dict;
         QCryptoBlockAmendOptions *amend_opts;
 
         helper_cb_info.current_operation = QCOW2_UPDATING_ENCRYPTION;
         amend_opts_dict = qcow2_extract_crypto_opts(opts, "luks", errp);
         if (!amend_opts_dict) {
             return -EINVAL;
         }
         amend_opts = block_crypto_amend_opts_init(amend_opts_dict, errp);
         qobject_unref(amend_opts_dict);
         if (!amend_opts) {
             return -EINVAL;
         }
         ret = qcrypto_block_amend_options(s->crypto,
                                           qcow2_crypto_hdr_read_func,
                                           qcow2_crypto_hdr_write_func,
                                           bs,
                                           amend_opts,
                                           force,
                                           errp);
         qapi_free_QCryptoBlockAmendOptions(amend_opts);
         if (ret < 0) {
             return ret;
         }
     }
 
     if (s->refcount_bits != refcount_bits) {
         int refcount_order = ctz32(refcount_bits);
 
         if (new_version < 3 && refcount_bits != 16) {
             error_setg(errp, "Refcount widths other than 16 bits require "
                        "compatibility level 1.1 or above (use compat=1.1 or "
                        "greater)");
             return -EINVAL;
         }
 
         helper_cb_info.current_operation = QCOW2_CHANGING_REFCOUNT_ORDER;
         ret = qcow2_change_refcount_order(bs, refcount_order,
                                           &qcow2_amend_helper_cb,
                                           &helper_cb_info, errp);
         if (ret < 0) {
             return ret;
         }
     }
 
     /* data-file-raw blocks backing files, so clear it first if requested */
     if (data_file_raw) {
         s->autoclear_features |= QCOW2_AUTOCLEAR_DATA_FILE_RAW;
     } else {
         s->autoclear_features &= ~QCOW2_AUTOCLEAR_DATA_FILE_RAW;
     }
 
     if (data_file) {
         g_free(s->image_data_file);
         s->image_data_file = *data_file ? g_strdup(data_file) : NULL;
     }
 
     ret = qcow2_update_header(bs);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to update the image header");
         return ret;
     }
 
     if (backing_file || backing_format) {
         if (g_strcmp0(backing_file, s->image_backing_file) ||
             g_strcmp0(backing_format, s->image_backing_format)) {
             error_setg(errp, "Cannot amend the backing file");
             error_append_hint(errp,
                               "You can use 'qemu-img rebase' instead.\n");
             return -EINVAL;
         }
     }
 
     if (s->use_lazy_refcounts != lazy_refcounts) {
         if (lazy_refcounts) {
             if (new_version < 3) {
                 error_setg(errp, "Lazy refcounts only supported with "
                            "compatibility level 1.1 and above (use compat=1.1 "
                            "or greater)");
                 return -EINVAL;
             }
             s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
             ret = qcow2_update_header(bs);
             if (ret < 0) {
                 s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
                 error_setg_errno(errp, -ret, "Failed to update the image header");
                 return ret;
             }
             s->use_lazy_refcounts = true;
         } else {
             /* make image clean first */
             ret = qcow2_mark_clean(bs);
             if (ret < 0) {
                 error_setg_errno(errp, -ret, "Failed to make the image clean");
                 return ret;
             }
             /* now disallow lazy refcounts */
             s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
             ret = qcow2_update_header(bs);
             if (ret < 0) {
                 s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
                 error_setg_errno(errp, -ret, "Failed to update the image header");
                 return ret;
             }
             s->use_lazy_refcounts = false;
         }
     }
 
     if (new_size) {
         BlockBackend *blk = blk_new_with_bs(bs, BLK_PERM_RESIZE, BLK_PERM_ALL,
                                             errp);
         if (!blk) {
             return -EPERM;
         }
 
         /*
          * Amending image options should ensure that the image has
          * exactly the given new values, so pass exact=true here.
          */
         ret = blk_truncate(blk, new_size, true, PREALLOC_MODE_OFF, 0, errp);
         blk_unref(blk);
         if (ret < 0) {
             return ret;
         }
     }
 
     /* Downgrade last (so unsupported features can be removed before) */
     if (new_version < old_version) {
         helper_cb_info.current_operation = QCOW2_DOWNGRADING;
         ret = qcow2_downgrade(bs, new_version, &qcow2_amend_helper_cb,
                               &helper_cb_info, errp);
         if (ret < 0) {
             return ret;
         }
     }
 
     return 0;
 }
 
 static int coroutine_fn qcow2_co_amend(BlockDriverState *bs,
                                        BlockdevAmendOptions *opts,
                                        bool force,
                                        Error **errp)
 {
     BlockdevAmendOptionsQcow2 *qopts = &opts->u.qcow2;
     BDRVQcow2State *s = bs->opaque;
     int ret = 0;
 
     if (qopts->has_encrypt) {
         if (!s->crypto) {
             error_setg(errp, "image is not encrypted, can't amend");
             return -EOPNOTSUPP;
         }
 
         if (qopts->encrypt->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
             error_setg(errp,
                        "Amend can't be used to change the qcow2 encryption format");
             return -EOPNOTSUPP;
         }
 
         if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
             error_setg(errp,
                        "Only LUKS encryption options can be amended for qcow2 with blockdev-amend");
             return -EOPNOTSUPP;
         }
 
         ret = qcrypto_block_amend_options(s->crypto,
                                           qcow2_crypto_hdr_read_func,
                                           qcow2_crypto_hdr_write_func,
                                           bs,
                                           qopts->encrypt,
                                           force,
                                           errp);
     }
     return ret;
 }
 
 /*
  * If offset or size are negative, respectively, they will not be included in
  * the BLOCK_IMAGE_CORRUPTED event emitted.
  * fatal will be ignored for read-only BDS; corruptions found there will always
  * be considered non-fatal.
  */
 void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
                              int64_t size, const char *message_format, ...)
 {
     BDRVQcow2State *s = bs->opaque;
     const char *node_name;
     char *message;
     va_list ap;
 
     fatal = fatal && bdrv_is_writable(bs);
 
     if (s->signaled_corruption &&
         (!fatal || (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT)))
     {
         return;
     }
 
     va_start(ap, message_format);
     message = g_strdup_vprintf(message_format, ap);
     va_end(ap);
 
     if (fatal) {
         fprintf(stderr, "qcow2: Marking image as corrupt: %s; further "
                 "corruption events will be suppressed\n", message);
     } else {
         fprintf(stderr, "qcow2: Image is corrupt: %s; further non-fatal "
                 "corruption events will be suppressed\n", message);
     }
 
     node_name = bdrv_get_node_name(bs);
     qapi_event_send_block_image_corrupted(bdrv_get_device_name(bs),
                                           *node_name != '\0', node_name,
                                           message, offset >= 0, offset,
                                           size >= 0, size,
                                           fatal);
     g_free(message);
 
     if (fatal) {
         qcow2_mark_corrupt(bs);
         bs->drv = NULL; /* make BDS unusable */
     }
 
     s->signaled_corruption = true;
 }
 
 #define QCOW_COMMON_OPTIONS                                         \
     {                                                               \
         .name = BLOCK_OPT_SIZE,                                     \
         .type = QEMU_OPT_SIZE,                                      \
         .help = "Virtual disk size"                                 \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_COMPAT_LEVEL,                             \
         .type = QEMU_OPT_STRING,                                    \
         .help = "Compatibility level (v2 [0.10] or v3 [1.1])"       \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_BACKING_FILE,                             \
         .type = QEMU_OPT_STRING,                                    \
         .help = "File name of a base image"                         \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_BACKING_FMT,                              \
         .type = QEMU_OPT_STRING,                                    \
         .help = "Image format of the base image"                    \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_DATA_FILE,                                \
         .type = QEMU_OPT_STRING,                                    \
         .help = "File name of an external data file"                \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_DATA_FILE_RAW,                            \
         .type = QEMU_OPT_BOOL,                                      \
         .help = "The external data file must stay valid "           \
                 "as a raw image"                                    \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_LAZY_REFCOUNTS,                           \
         .type = QEMU_OPT_BOOL,                                      \
         .help = "Postpone refcount updates",                        \
         .def_value_str = "off"                                      \
     },                                                              \
     {                                                               \
         .name = BLOCK_OPT_REFCOUNT_BITS,                            \
         .type = QEMU_OPT_NUMBER,                                    \
         .help = "Width of a reference count entry in bits",         \
         .def_value_str = "16"                                       \
     }
 
 static QemuOptsList qcow2_create_opts = {
     .name = "qcow2-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(qcow2_create_opts.head),
     .desc = {
         {                                                               \
             .name = BLOCK_OPT_ENCRYPT,                                  \
             .type = QEMU_OPT_BOOL,                                      \
             .help = "Encrypt the image with format 'aes'. (Deprecated " \
                     "in favor of " BLOCK_OPT_ENCRYPT_FORMAT "=aes)",    \
         },                                                              \
         {                                                               \
             .name = BLOCK_OPT_ENCRYPT_FORMAT,                           \
             .type = QEMU_OPT_STRING,                                    \
             .help = "Encrypt the image, format choices: 'aes', 'luks'", \
         },                                                              \
         BLOCK_CRYPTO_OPT_DEF_KEY_SECRET("encrypt.",                     \
             "ID of secret providing qcow AES key or LUKS passphrase"),  \
         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_ALG("encrypt."),               \
         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_MODE("encrypt."),              \
         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_ALG("encrypt."),                \
         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_HASH_ALG("encrypt."),           \
         BLOCK_CRYPTO_OPT_DEF_LUKS_HASH_ALG("encrypt."),                 \
         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME("encrypt."),                \
         {                                                               \
             .name = BLOCK_OPT_CLUSTER_SIZE,                             \
             .type = QEMU_OPT_SIZE,                                      \
             .help = "qcow2 cluster size",                               \
             .def_value_str = stringify(DEFAULT_CLUSTER_SIZE)            \
         },                                                              \
         {                                                               \
             .name = BLOCK_OPT_EXTL2,                                    \
             .type = QEMU_OPT_BOOL,                                      \
             .help = "Extended L2 tables",                               \
             .def_value_str = "off"                                      \
         },                                                              \
         {                                                               \
             .name = BLOCK_OPT_PREALLOC,                                 \
             .type = QEMU_OPT_STRING,                                    \
             .help = "Preallocation mode (allowed values: off, "         \
                     "metadata, falloc, full)"                           \
         },                                                              \
         {                                                               \
             .name = BLOCK_OPT_COMPRESSION_TYPE,                         \
             .type = QEMU_OPT_STRING,                                    \
             .help = "Compression method used for image cluster "        \
                     "compression",                                      \
             .def_value_str = "zlib"                                     \
         },
         QCOW_COMMON_OPTIONS,
         { /* end of list */ }
     }
 };
 
 static QemuOptsList qcow2_amend_opts = {
     .name = "qcow2-amend-opts",
     .head = QTAILQ_HEAD_INITIALIZER(qcow2_amend_opts.head),
     .desc = {
         BLOCK_CRYPTO_OPT_DEF_LUKS_STATE("encrypt."),
         BLOCK_CRYPTO_OPT_DEF_LUKS_KEYSLOT("encrypt."),
         BLOCK_CRYPTO_OPT_DEF_LUKS_OLD_SECRET("encrypt."),
         BLOCK_CRYPTO_OPT_DEF_LUKS_NEW_SECRET("encrypt."),
         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME("encrypt."),
         QCOW_COMMON_OPTIONS,
         { /* end of list */ }
     }
 };
 
 static const char *const qcow2_strong_runtime_opts[] = {
     "encrypt." BLOCK_CRYPTO_OPT_QCOW_KEY_SECRET,
 
     NULL
 };
 
 BlockDriver bdrv_qcow2 = {
     .format_name        = "qcow2",
     .instance_size      = sizeof(BDRVQcow2State),
     .bdrv_probe         = qcow2_probe,
     .bdrv_open          = qcow2_open,
     .bdrv_close         = qcow2_close,
     .bdrv_reopen_prepare  = qcow2_reopen_prepare,
     .bdrv_reopen_commit   = qcow2_reopen_commit,
     .bdrv_reopen_commit_post = qcow2_reopen_commit_post,
     .bdrv_reopen_abort    = qcow2_reopen_abort,
     .bdrv_join_options    = qcow2_join_options,
     .bdrv_child_perm      = bdrv_default_perms,
     .bdrv_co_create_opts  = qcow2_co_create_opts,
     .bdrv_co_create       = qcow2_co_create,
     .bdrv_has_zero_init   = qcow2_has_zero_init,
     .bdrv_co_block_status = qcow2_co_block_status,
 
     .bdrv_co_preadv_part    = qcow2_co_preadv_part,
     .bdrv_co_pwritev_part   = qcow2_co_pwritev_part,
     .bdrv_co_flush_to_os    = qcow2_co_flush_to_os,
 
     .bdrv_co_pwrite_zeroes  = qcow2_co_pwrite_zeroes,
     .bdrv_co_pdiscard       = qcow2_co_pdiscard,
     .bdrv_co_copy_range_from = qcow2_co_copy_range_from,
     .bdrv_co_copy_range_to  = qcow2_co_copy_range_to,
     .bdrv_co_truncate       = qcow2_co_truncate,
     .bdrv_co_pwritev_compressed_part = qcow2_co_pwritev_compressed_part,
     .bdrv_make_empty        = qcow2_make_empty,
 
     .bdrv_snapshot_create   = qcow2_snapshot_create,
     .bdrv_snapshot_goto     = qcow2_snapshot_goto,
     .bdrv_snapshot_delete   = qcow2_snapshot_delete,
     .bdrv_snapshot_list     = qcow2_snapshot_list,
     .bdrv_snapshot_load_tmp = qcow2_snapshot_load_tmp,
     .bdrv_measure           = qcow2_measure,
     .bdrv_get_info          = qcow2_get_info,
     .bdrv_get_specific_info = qcow2_get_specific_info,
 
     .bdrv_save_vmstate    = qcow2_save_vmstate,
     .bdrv_load_vmstate    = qcow2_load_vmstate,
 
     .is_format                  = true,
     .supports_backing           = true,
     .bdrv_change_backing_file   = qcow2_change_backing_file,
 
     .bdrv_refresh_limits        = qcow2_refresh_limits,
     .bdrv_co_invalidate_cache   = qcow2_co_invalidate_cache,
     .bdrv_inactivate            = qcow2_inactivate,
 
     .create_opts         = &qcow2_create_opts,
     .amend_opts          = &qcow2_amend_opts,
     .strong_runtime_opts = qcow2_strong_runtime_opts,
     .mutable_opts        = mutable_opts,
     .bdrv_co_check       = qcow2_co_check,
     .bdrv_amend_options  = qcow2_amend_options,
     .bdrv_co_amend       = qcow2_co_amend,
 
     .bdrv_detach_aio_context  = qcow2_detach_aio_context,
     .bdrv_attach_aio_context  = qcow2_attach_aio_context,
 
     .bdrv_supports_persistent_dirty_bitmap =
             qcow2_supports_persistent_dirty_bitmap,
     .bdrv_co_can_store_new_dirty_bitmap = qcow2_co_can_store_new_dirty_bitmap,
     .bdrv_co_remove_persistent_dirty_bitmap =
             qcow2_co_remove_persistent_dirty_bitmap,
 };
 
 static void bdrv_qcow2_init(void)
 {
     bdrv_register(&bdrv_qcow2);
 }
 
 block_init(bdrv_qcow2_init);