qemu

vhdx.c (75621B)

---

 /*
  * Block driver for Hyper-V VHDX Images
  *
  * Copyright (c) 2013 Red Hat, Inc.,
  *
  * Authors:
  *  Jeff Cody <jcody@redhat.com>
  *
  *  This is based on the "VHDX Format Specification v1.00", published 8/25/2012
  *  by Microsoft:
  *      https://www.microsoft.com/en-us/download/details.aspx?id=34750
  *
  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  * See the COPYING.LIB file in the top-level directory.
  *
  */
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "block/block_int.h"
 #include "block/qdict.h"
 #include "sysemu/block-backend.h"
 #include "qemu/module.h"
 #include "qemu/option.h"
 #include "qemu/crc32c.h"
 #include "qemu/bswap.h"
 #include "qemu/error-report.h"
 #include "qemu/memalign.h"
 #include "vhdx.h"
 #include "migration/blocker.h"
 #include "qemu/uuid.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qobject-input-visitor.h"
 #include "qapi/qapi-visit-block-core.h"
 
 /* Options for VHDX creation */
 
 #define VHDX_BLOCK_OPT_LOG_SIZE   "log_size"
 #define VHDX_BLOCK_OPT_BLOCK_SIZE "block_size"
 #define VHDX_BLOCK_OPT_ZERO "block_state_zero"
 
 typedef enum VHDXImageType {
     VHDX_TYPE_DYNAMIC = 0,
     VHDX_TYPE_FIXED,
     VHDX_TYPE_DIFFERENCING,   /* Currently unsupported */
 } VHDXImageType;
 
 static QemuOptsList vhdx_create_opts;
 
 /* Several metadata and region table data entries are identified by
  * guids in  a MS-specific GUID format. */
 
 
 /* ------- Known Region Table GUIDs ---------------------- */
 static const MSGUID bat_guid =      { .data1 = 0x2dc27766,
                                       .data2 = 0xf623,
                                       .data3 = 0x4200,
                                       .data4 = { 0x9d, 0x64, 0x11, 0x5e,
                                                  0x9b, 0xfd, 0x4a, 0x08} };
 
 static const MSGUID metadata_guid = { .data1 = 0x8b7ca206,
                                       .data2 = 0x4790,
                                       .data3 = 0x4b9a,
                                       .data4 = { 0xb8, 0xfe, 0x57, 0x5f,
                                                  0x05, 0x0f, 0x88, 0x6e} };
 
 
 
 /* ------- Known Metadata Entry GUIDs ---------------------- */
 static const MSGUID file_param_guid =   { .data1 = 0xcaa16737,
                                           .data2 = 0xfa36,
                                           .data3 = 0x4d43,
                                           .data4 = { 0xb3, 0xb6, 0x33, 0xf0,
                                                      0xaa, 0x44, 0xe7, 0x6b} };
 
 static const MSGUID virtual_size_guid = { .data1 = 0x2FA54224,
                                           .data2 = 0xcd1b,
                                           .data3 = 0x4876,
                                           .data4 = { 0xb2, 0x11, 0x5d, 0xbe,
                                                      0xd8, 0x3b, 0xf4, 0xb8} };
 
 static const MSGUID page83_guid =       { .data1 = 0xbeca12ab,
                                           .data2 = 0xb2e6,
                                           .data3 = 0x4523,
                                           .data4 = { 0x93, 0xef, 0xc3, 0x09,
                                                      0xe0, 0x00, 0xc7, 0x46} };
 
 
 static const MSGUID phys_sector_guid =  { .data1 = 0xcda348c7,
                                           .data2 = 0x445d,
                                           .data3 = 0x4471,
                                           .data4 = { 0x9c, 0xc9, 0xe9, 0x88,
                                                      0x52, 0x51, 0xc5, 0x56} };
 
 static const MSGUID parent_locator_guid = { .data1 = 0xa8d35f2d,
                                             .data2 = 0xb30b,
                                             .data3 = 0x454d,
                                             .data4 = { 0xab, 0xf7, 0xd3,
                                                        0xd8, 0x48, 0x34,
                                                        0xab, 0x0c} };
 
 static const MSGUID logical_sector_guid = { .data1 = 0x8141bf1d,
                                             .data2 = 0xa96f,
                                             .data3 = 0x4709,
                                             .data4 = { 0xba, 0x47, 0xf2,
                                                        0x33, 0xa8, 0xfa,
                                                        0xab, 0x5f} };
 
 /* Each parent type must have a valid GUID; this is for parent images
  * of type 'VHDX'.  If we were to allow e.g. a QCOW2 parent, we would
  * need to make up our own QCOW2 GUID type */
 static const MSGUID parent_vhdx_guid __attribute__((unused))
                                      = { .data1 = 0xb04aefb7,
                                          .data2 = 0xd19e,
                                          .data3 = 0x4a81,
                                          .data4 = { 0xb7, 0x89, 0x25, 0xb8,
                                                     0xe9, 0x44, 0x59, 0x13} };
 
 
 #define META_FILE_PARAMETER_PRESENT      0x01
 #define META_VIRTUAL_DISK_SIZE_PRESENT   0x02
 #define META_PAGE_83_PRESENT             0x04
 #define META_LOGICAL_SECTOR_SIZE_PRESENT 0x08
 #define META_PHYS_SECTOR_SIZE_PRESENT    0x10
 #define META_PARENT_LOCATOR_PRESENT      0x20
 
 #define META_ALL_PRESENT    \
     (META_FILE_PARAMETER_PRESENT | META_VIRTUAL_DISK_SIZE_PRESENT | \
      META_PAGE_83_PRESENT | META_LOGICAL_SECTOR_SIZE_PRESENT | \
      META_PHYS_SECTOR_SIZE_PRESENT)
 
 
 typedef struct VHDXSectorInfo {
     uint32_t bat_idx;       /* BAT entry index */
     uint32_t sectors_avail; /* sectors available in payload block */
     uint32_t bytes_left;    /* bytes left in the block after data to r/w */
     uint32_t bytes_avail;   /* bytes available in payload block */
     uint64_t file_offset;   /* absolute offset in bytes, in file */
     uint64_t block_offset;  /* block offset, in bytes */
 } VHDXSectorInfo;
 
 /* Calculates new checksum.
  *
  * Zero is substituted during crc calculation for the original crc field
  * crc_offset: byte offset in buf of the buffer crc
  * buf: buffer pointer
  * size: size of buffer (must be > crc_offset+4)
  *
  * Note: The buffer should have all multi-byte data in little-endian format,
  *       and the resulting checksum is in little endian format.
  */
 uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset)
 {
     uint32_t crc;
 
     assert(buf != NULL);
     assert(size > (crc_offset + sizeof(crc)));
 
     memset(buf + crc_offset, 0, sizeof(crc));
     crc =  crc32c(0xffffffff, buf, size);
     crc = cpu_to_le32(crc);
     memcpy(buf + crc_offset, &crc, sizeof(crc));
 
     return crc;
 }
 
 uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
                             int crc_offset)
 {
     uint32_t crc_new;
     uint32_t crc_orig;
     assert(buf != NULL);
 
     if (crc_offset > 0) {
         memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig));
         memset(buf + crc_offset, 0, sizeof(crc_orig));
     }
 
     crc_new = crc32c(crc, buf, size);
     if (crc_offset > 0) {
         memcpy(buf + crc_offset, &crc_orig, sizeof(crc_orig));
     }
 
     return crc_new;
 }
 
 /* Validates the checksum of the buffer, with an in-place CRC.
  *
  * Zero is substituted during crc calculation for the original crc field,
  * and the crc field is restored afterwards.  But the buffer will be modified
  * during the calculation, so this may not be not suitable for multi-threaded
  * use.
  *
  * crc_offset: byte offset in buf of the buffer crc
  * buf: buffer pointer
  * size: size of buffer (must be > crc_offset+4)
  *
  * returns true if checksum is valid, false otherwise
  */
 bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset)
 {
     uint32_t crc_orig;
     uint32_t crc;
 
     assert(buf != NULL);
     assert(size > (crc_offset + 4));
 
     memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig));
     crc_orig = le32_to_cpu(crc_orig);
 
     crc = vhdx_checksum_calc(0xffffffff, buf, size, crc_offset);
 
     return crc == crc_orig;
 }
 
 
 /*
  * This generates a UUID that is compliant with the MS GUIDs used
  * in the VHDX spec (and elsewhere).
  */
 void vhdx_guid_generate(MSGUID *guid)
 {
     QemuUUID uuid;
     assert(guid != NULL);
 
     qemu_uuid_generate(&uuid);
     memcpy(guid, &uuid, sizeof(MSGUID));
 }
 
 /* Check for region overlaps inside the VHDX image */
 static int vhdx_region_check(BDRVVHDXState *s, uint64_t start, uint64_t length)
 {
     int ret = 0;
     uint64_t end;
     VHDXRegionEntry *r;
 
     end = start + length;
     QLIST_FOREACH(r, &s->regions, entries) {
         if (!((start >= r->end) || (end <= r->start))) {
             error_report("VHDX region %" PRIu64 "-%" PRIu64 " overlaps with "
                          "region %" PRIu64 "-%." PRIu64, start, end, r->start,
                          r->end);
             ret = -EINVAL;
             goto exit;
         }
     }
 
 exit:
     return ret;
 }
 
 /* Register a region for future checks */
 static void vhdx_region_register(BDRVVHDXState *s,
                                  uint64_t start, uint64_t length)
 {
     VHDXRegionEntry *r;
 
     r = g_malloc0(sizeof(*r));
 
     r->start = start;
     r->end = start + length;
 
     QLIST_INSERT_HEAD(&s->regions, r, entries);
 }
 
 /* Free all registered regions */
 static void vhdx_region_unregister_all(BDRVVHDXState *s)
 {
     VHDXRegionEntry *r, *r_next;
 
     QLIST_FOREACH_SAFE(r, &s->regions, entries, r_next) {
         QLIST_REMOVE(r, entries);
         g_free(r);
     }
 }
 
 static void vhdx_set_shift_bits(BDRVVHDXState *s)
 {
     s->logical_sector_size_bits = ctz32(s->logical_sector_size);
     s->sectors_per_block_bits =   ctz32(s->sectors_per_block);
     s->chunk_ratio_bits =         ctz64(s->chunk_ratio);
     s->block_size_bits =          ctz32(s->block_size);
 }
 
 /*
  * Per the MS VHDX Specification, for every VHDX file:
  *      - The header section is fixed size - 1 MB
  *      - The header section is always the first "object"
  *      - The first 64KB of the header is the File Identifier
  *      - The first uint64 (8 bytes) is the VHDX Signature ("vhdxfile")
  *      - The following 512 bytes constitute a UTF-16 string identifiying the
  *        software that created the file, and is optional and diagnostic only.
  *
  *  Therefore, we probe by looking for the vhdxfile signature "vhdxfile"
  */
 static int vhdx_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
     if (buf_size >= 8 && !memcmp(buf, "vhdxfile", 8)) {
         return 100;
     }
     return 0;
 }
 
 /*
  * Writes the header to the specified offset.
  *
  * This will optionally read in buffer data from disk (otherwise zero-fill),
  * and then update the header checksum.  Header is converted to proper
  * endianness before being written to the specified file offset
  */
 static int vhdx_write_header(BdrvChild *file, VHDXHeader *hdr,
                              uint64_t offset, bool read)
 {
     BlockDriverState *bs_file = file->bs;
     uint8_t *buffer = NULL;
     int ret;
     VHDXHeader *header_le;
 
     assert(bs_file != NULL);
     assert(hdr != NULL);
 
     /* the header checksum is not over just the packed size of VHDXHeader,
      * but rather over the entire 'reserved' range for the header, which is
      * 4KB (VHDX_HEADER_SIZE). */
 
     buffer = qemu_blockalign(bs_file, VHDX_HEADER_SIZE);
     if (read) {
         /* if true, we can't assume the extra reserved bytes are 0 */
         ret = bdrv_pread(file, offset, VHDX_HEADER_SIZE, buffer, 0);
         if (ret < 0) {
             goto exit;
         }
     } else {
         memset(buffer, 0, VHDX_HEADER_SIZE);
     }
 
     /* overwrite the actual VHDXHeader portion */
     header_le = (VHDXHeader *)buffer;
     memcpy(header_le, hdr, sizeof(VHDXHeader));
     vhdx_header_le_export(hdr, header_le);
     vhdx_update_checksum(buffer, VHDX_HEADER_SIZE,
                          offsetof(VHDXHeader, checksum));
     ret = bdrv_pwrite_sync(file, offset, sizeof(VHDXHeader), header_le, 0);
 
 exit:
     qemu_vfree(buffer);
     return ret;
 }
 
 /* Update the VHDX headers
  *
  * This follows the VHDX spec procedures for header updates.
  *
  *  - non-current header is updated with largest sequence number
  */
 static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s,
                               bool generate_data_write_guid, MSGUID *log_guid)
 {
     int ret = 0;
     int hdr_idx = 0;
     uint64_t header_offset = VHDX_HEADER1_OFFSET;
 
     VHDXHeader *active_header;
     VHDXHeader *inactive_header;
 
     /* operate on the non-current header */
     if (s->curr_header == 0) {
         hdr_idx = 1;
         header_offset = VHDX_HEADER2_OFFSET;
     }
 
     active_header   = s->headers[s->curr_header];
     inactive_header = s->headers[hdr_idx];
 
     inactive_header->sequence_number = active_header->sequence_number + 1;
 
     /* a new file guid must be generated before any file write, including
      * headers */
     inactive_header->file_write_guid = s->session_guid;
 
     /* a new data guid only needs to be generated before any guest-visible
      * writes (i.e. something observable via virtual disk read) */
     if (generate_data_write_guid) {
         vhdx_guid_generate(&inactive_header->data_write_guid);
     }
 
     /* update the log guid if present */
     if (log_guid) {
         inactive_header->log_guid = *log_guid;
     }
 
     ret = vhdx_write_header(bs->file, inactive_header, header_offset, true);
     if (ret < 0) {
         goto exit;
     }
     s->curr_header = hdr_idx;
 
 exit:
     return ret;
 }
 
 /*
  * The VHDX spec calls for header updates to be performed twice, so that both
  * the current and non-current header have valid info
  */
 int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s,
                         bool generate_data_write_guid, MSGUID *log_guid)
 {
     int ret;
 
     ret = vhdx_update_header(bs, s, generate_data_write_guid, log_guid);
     if (ret < 0) {
         return ret;
     }
     return vhdx_update_header(bs, s, generate_data_write_guid, log_guid);
 }
 
 /* opens the specified header block from the VHDX file header section */
 static void vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s,
                               Error **errp)
 {
     int ret;
     VHDXHeader *header1;
     VHDXHeader *header2;
     bool h1_valid = false;
     bool h2_valid = false;
     uint64_t h1_seq = 0;
     uint64_t h2_seq = 0;
     uint8_t *buffer;
 
     /* header1 & header2 are freed in vhdx_close() */
     header1 = qemu_blockalign(bs, sizeof(VHDXHeader));
     header2 = qemu_blockalign(bs, sizeof(VHDXHeader));
 
     buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE);
 
     s->headers[0] = header1;
     s->headers[1] = header2;
 
     /* We have to read the whole VHDX_HEADER_SIZE instead of
      * sizeof(VHDXHeader), because the checksum is over the whole
      * region */
     ret = bdrv_pread(bs->file, VHDX_HEADER1_OFFSET, VHDX_HEADER_SIZE, buffer,
                      0);
     if (ret < 0) {
         goto fail;
     }
     /* copy over just the relevant portion that we need */
     memcpy(header1, buffer, sizeof(VHDXHeader));
 
     if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4)) {
         vhdx_header_le_import(header1);
         if (header1->signature == VHDX_HEADER_SIGNATURE &&
             header1->version == 1) {
             h1_seq = header1->sequence_number;
             h1_valid = true;
         }
     }
 
     ret = bdrv_pread(bs->file, VHDX_HEADER2_OFFSET, VHDX_HEADER_SIZE, buffer,
                      0);
     if (ret < 0) {
         goto fail;
     }
     /* copy over just the relevant portion that we need */
     memcpy(header2, buffer, sizeof(VHDXHeader));
 
     if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4)) {
         vhdx_header_le_import(header2);
         if (header2->signature == VHDX_HEADER_SIGNATURE &&
             header2->version == 1) {
             h2_seq = header2->sequence_number;
             h2_valid = true;
         }
     }
 
     /* If there is only 1 valid header (or no valid headers), we
      * don't care what the sequence numbers are */
     if (h1_valid && !h2_valid) {
         s->curr_header = 0;
     } else if (!h1_valid && h2_valid) {
         s->curr_header = 1;
     } else if (!h1_valid && !h2_valid) {
         goto fail;
     } else {
         /* If both headers are valid, then we choose the active one by the
          * highest sequence number.  If the sequence numbers are equal, that is
          * invalid */
         if (h1_seq > h2_seq) {
             s->curr_header = 0;
         } else if (h2_seq > h1_seq) {
             s->curr_header = 1;
         } else {
             /* The Microsoft Disk2VHD tool will create 2 identical
              * headers, with identical sequence numbers.  If the headers are
              * identical, don't consider the file corrupt */
             if (!memcmp(header1, header2, sizeof(VHDXHeader))) {
                 s->curr_header = 0;
             } else {
                 goto fail;
             }
         }
     }
 
     vhdx_region_register(s, s->headers[s->curr_header]->log_offset,
                             s->headers[s->curr_header]->log_length);
     goto exit;
 
 fail:
     error_setg_errno(errp, -ret, "No valid VHDX header found");
     qemu_vfree(header1);
     qemu_vfree(header2);
     s->headers[0] = NULL;
     s->headers[1] = NULL;
 exit:
     qemu_vfree(buffer);
 }
 
 
 static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s)
 {
     int ret = 0;
     uint8_t *buffer;
     int offset = 0;
     VHDXRegionTableEntry rt_entry;
     uint32_t i;
     bool bat_rt_found = false;
     bool metadata_rt_found = false;
 
     /* We have to read the whole 64KB block, because the crc32 is over the
      * whole block */
     buffer = qemu_blockalign(bs, VHDX_HEADER_BLOCK_SIZE);
 
     ret = bdrv_pread(bs->file, VHDX_REGION_TABLE_OFFSET,
                      VHDX_HEADER_BLOCK_SIZE, buffer, 0);
     if (ret < 0) {
         goto fail;
     }
     memcpy(&s->rt, buffer, sizeof(s->rt));
     offset += sizeof(s->rt);
 
     if (!vhdx_checksum_is_valid(buffer, VHDX_HEADER_BLOCK_SIZE, 4)) {
         ret = -EINVAL;
         goto fail;
     }
 
     vhdx_region_header_le_import(&s->rt);
 
     if (s->rt.signature != VHDX_REGION_SIGNATURE) {
         ret = -EINVAL;
         goto fail;
     }
 
 
     /* Per spec, maximum region table entry count is 2047 */
     if (s->rt.entry_count > 2047) {
         ret = -EINVAL;
         goto fail;
     }
 
     for (i = 0; i < s->rt.entry_count; i++) {
         memcpy(&rt_entry, buffer + offset, sizeof(rt_entry));
         offset += sizeof(rt_entry);
 
         vhdx_region_entry_le_import(&rt_entry);
 
         /* check for region overlap between these entries, and any
          * other memory regions in the file */
         ret = vhdx_region_check(s, rt_entry.file_offset, rt_entry.length);
         if (ret < 0) {
             goto fail;
         }
 
         vhdx_region_register(s, rt_entry.file_offset, rt_entry.length);
 
         /* see if we recognize the entry */
         if (guid_eq(rt_entry.guid, bat_guid)) {
             /* must be unique; if we have already found it this is invalid */
             if (bat_rt_found) {
                 ret = -EINVAL;
                 goto fail;
             }
             bat_rt_found = true;
             s->bat_rt = rt_entry;
             continue;
         }
 
         if (guid_eq(rt_entry.guid, metadata_guid)) {
             /* must be unique; if we have already found it this is invalid */
             if (metadata_rt_found) {
                 ret = -EINVAL;
                 goto fail;
             }
             metadata_rt_found = true;
             s->metadata_rt = rt_entry;
             continue;
         }
 
         if (rt_entry.data_bits & VHDX_REGION_ENTRY_REQUIRED) {
             /* cannot read vhdx file - required region table entry that
              * we do not understand.  per spec, we must fail to open */
             ret = -ENOTSUP;
             goto fail;
         }
     }
 
     if (!bat_rt_found || !metadata_rt_found) {
         ret = -EINVAL;
         goto fail;
     }
 
     ret = 0;
 
 fail:
     qemu_vfree(buffer);
     return ret;
 }
 
 
 
 /* Metadata initial parser
  *
  * This loads all the metadata entry fields.  This may cause additional
  * fields to be processed (e.g. parent locator, etc..).
  *
  * There are 5 Metadata items that are always required:
  *      - File Parameters (block size, has a parent)
  *      - Virtual Disk Size (size, in bytes, of the virtual drive)
  *      - Page 83 Data (scsi page 83 guid)
  *      - Logical Sector Size (logical sector size in bytes, either 512 or
  *                             4096.  We only support 512 currently)
  *      - Physical Sector Size (512 or 4096)
  *
  * Also, if the File Parameters indicate this is a differencing file,
  * we must also look for the Parent Locator metadata item.
  */
 static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s)
 {
     int ret = 0;
     uint8_t *buffer;
     int offset = 0;
     uint32_t i = 0;
     VHDXMetadataTableEntry md_entry;
 
     buffer = qemu_blockalign(bs, VHDX_METADATA_TABLE_MAX_SIZE);
 
     ret = bdrv_pread(bs->file, s->metadata_rt.file_offset,
                      VHDX_METADATA_TABLE_MAX_SIZE, buffer, 0);
     if (ret < 0) {
         goto exit;
     }
     memcpy(&s->metadata_hdr, buffer, sizeof(s->metadata_hdr));
     offset += sizeof(s->metadata_hdr);
 
     vhdx_metadata_header_le_import(&s->metadata_hdr);
 
     if (s->metadata_hdr.signature != VHDX_METADATA_SIGNATURE) {
         ret = -EINVAL;
         goto exit;
     }
 
     s->metadata_entries.present = 0;
 
     if ((s->metadata_hdr.entry_count * sizeof(md_entry)) >
         (VHDX_METADATA_TABLE_MAX_SIZE - offset)) {
         ret = -EINVAL;
         goto exit;
     }
 
     for (i = 0; i < s->metadata_hdr.entry_count; i++) {
         memcpy(&md_entry, buffer + offset, sizeof(md_entry));
         offset += sizeof(md_entry);
 
         vhdx_metadata_entry_le_import(&md_entry);
 
         if (guid_eq(md_entry.item_id, file_param_guid)) {
             if (s->metadata_entries.present & META_FILE_PARAMETER_PRESENT) {
                 ret = -EINVAL;
                 goto exit;
             }
             s->metadata_entries.file_parameters_entry = md_entry;
             s->metadata_entries.present |= META_FILE_PARAMETER_PRESENT;
             continue;
         }
 
         if (guid_eq(md_entry.item_id, virtual_size_guid)) {
             if (s->metadata_entries.present & META_VIRTUAL_DISK_SIZE_PRESENT) {
                 ret = -EINVAL;
                 goto exit;
             }
             s->metadata_entries.virtual_disk_size_entry = md_entry;
             s->metadata_entries.present |= META_VIRTUAL_DISK_SIZE_PRESENT;
             continue;
         }
 
         if (guid_eq(md_entry.item_id, page83_guid)) {
             if (s->metadata_entries.present & META_PAGE_83_PRESENT) {
                 ret = -EINVAL;
                 goto exit;
             }
             s->metadata_entries.page83_data_entry = md_entry;
             s->metadata_entries.present |= META_PAGE_83_PRESENT;
             continue;
         }
 
         if (guid_eq(md_entry.item_id, logical_sector_guid)) {
             if (s->metadata_entries.present &
                 META_LOGICAL_SECTOR_SIZE_PRESENT) {
                 ret = -EINVAL;
                 goto exit;
             }
             s->metadata_entries.logical_sector_size_entry = md_entry;
             s->metadata_entries.present |= META_LOGICAL_SECTOR_SIZE_PRESENT;
             continue;
         }
 
         if (guid_eq(md_entry.item_id, phys_sector_guid)) {
             if (s->metadata_entries.present & META_PHYS_SECTOR_SIZE_PRESENT) {
                 ret = -EINVAL;
                 goto exit;
             }
             s->metadata_entries.phys_sector_size_entry = md_entry;
             s->metadata_entries.present |= META_PHYS_SECTOR_SIZE_PRESENT;
             continue;
         }
 
         if (guid_eq(md_entry.item_id, parent_locator_guid)) {
             if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) {
                 ret = -EINVAL;
                 goto exit;
             }
             s->metadata_entries.parent_locator_entry = md_entry;
             s->metadata_entries.present |= META_PARENT_LOCATOR_PRESENT;
             continue;
         }
 
         if (md_entry.data_bits & VHDX_META_FLAGS_IS_REQUIRED) {
             /* cannot read vhdx file - required region table entry that
              * we do not understand.  per spec, we must fail to open */
             ret = -ENOTSUP;
             goto exit;
         }
     }
 
     if (s->metadata_entries.present != META_ALL_PRESENT) {
         ret = -ENOTSUP;
         goto exit;
     }
 
     ret = bdrv_pread(bs->file,
                      s->metadata_entries.file_parameters_entry.offset
                                          + s->metadata_rt.file_offset,
                      sizeof(s->params),
                      &s->params,
                      0);
 
     if (ret < 0) {
         goto exit;
     }
 
     s->params.block_size = le32_to_cpu(s->params.block_size);
     s->params.data_bits = le32_to_cpu(s->params.data_bits);
 
 
     /* We now have the file parameters, so we can tell if this is a
      * differencing file (i.e.. has_parent), is dynamic or fixed
      * sized (leave_blocks_allocated), and the block size */
 
     /* The parent locator required iff the file parameters has_parent set */
     if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
         if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) {
             /* TODO: parse  parent locator fields */
             ret = -ENOTSUP; /* temp, until differencing files are supported */
             goto exit;
         } else {
             /* if has_parent is set, but there is not parent locator present,
              * then that is an invalid combination */
             ret = -EINVAL;
             goto exit;
         }
     }
 
     /* determine virtual disk size, logical sector size,
      * and phys sector size */
 
     ret = bdrv_pread(bs->file,
                      s->metadata_entries.virtual_disk_size_entry.offset
                                            + s->metadata_rt.file_offset,
                      sizeof(uint64_t),
                      &s->virtual_disk_size,
                      0);
     if (ret < 0) {
         goto exit;
     }
     ret = bdrv_pread(bs->file,
                      s->metadata_entries.logical_sector_size_entry.offset
                                              + s->metadata_rt.file_offset,
                      sizeof(uint32_t),
                      &s->logical_sector_size,
                      0);
     if (ret < 0) {
         goto exit;
     }
     ret = bdrv_pread(bs->file,
                      s->metadata_entries.phys_sector_size_entry.offset
                                           + s->metadata_rt.file_offset,
                      sizeof(uint32_t),
                      &s->physical_sector_size,
                      0);
     if (ret < 0) {
         goto exit;
     }
 
     s->virtual_disk_size = le64_to_cpu(s->virtual_disk_size);
     s->logical_sector_size = le32_to_cpu(s->logical_sector_size);
     s->physical_sector_size = le32_to_cpu(s->physical_sector_size);
 
     if (s->params.block_size < VHDX_BLOCK_SIZE_MIN ||
         s->params.block_size > VHDX_BLOCK_SIZE_MAX) {
         ret = -EINVAL;
         goto exit;
     }
 
     /* Currently we only support 512 */
     if (s->logical_sector_size != 512) {
         ret = -ENOTSUP;
         goto exit;
     }
 
     /* Both block_size and sector_size are guaranteed powers of 2, below.
        Due to range checks above, s->sectors_per_block can never be < 256 */
     s->sectors_per_block = s->params.block_size / s->logical_sector_size;
     s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) *
                      (uint64_t)s->logical_sector_size /
                      (uint64_t)s->params.block_size;
 
     /* These values are ones we will want to use for division / multiplication
      * later on, and they are all guaranteed (per the spec) to be powers of 2,
      * so we can take advantage of that for shift operations during
      * reads/writes */
     if (s->logical_sector_size & (s->logical_sector_size - 1)) {
         ret = -EINVAL;
         goto exit;
     }
     if (s->sectors_per_block & (s->sectors_per_block - 1)) {
         ret = -EINVAL;
         goto exit;
     }
     if (s->chunk_ratio & (s->chunk_ratio - 1)) {
         ret = -EINVAL;
         goto exit;
     }
     s->block_size = s->params.block_size;
     if (s->block_size & (s->block_size - 1)) {
         ret = -EINVAL;
         goto exit;
     }
 
     vhdx_set_shift_bits(s);
 
     ret = 0;
 
 exit:
     qemu_vfree(buffer);
     return ret;
 }
 
 /*
  * Calculate the number of BAT entries, including sector
  * bitmap entries.
  */
 static void vhdx_calc_bat_entries(BDRVVHDXState *s)
 {
     uint32_t data_blocks_cnt, bitmap_blocks_cnt;
 
     data_blocks_cnt = DIV_ROUND_UP(s->virtual_disk_size, s->block_size);
     bitmap_blocks_cnt = DIV_ROUND_UP(data_blocks_cnt, s->chunk_ratio);
 
     if (s->parent_entries) {
         s->bat_entries = bitmap_blocks_cnt * (s->chunk_ratio + 1);
     } else {
         s->bat_entries = data_blocks_cnt +
                          ((data_blocks_cnt - 1) >> s->chunk_ratio_bits);
     }
 
 }
 
 static int vhdx_check_bat_entries(BlockDriverState *bs, int *errcnt)
 {
     BDRVVHDXState *s = bs->opaque;
     int64_t image_file_size = bdrv_getlength(bs->file->bs);
     uint64_t payblocks = s->chunk_ratio;
     uint64_t i;
     int ret = 0;
 
     if (image_file_size < 0) {
         error_report("Could not determinate VHDX image file size.");
         return image_file_size;
     }
 
     for (i = 0; i < s->bat_entries; i++) {
         if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) ==
             PAYLOAD_BLOCK_FULLY_PRESENT) {
             uint64_t offset = s->bat[i] & VHDX_BAT_FILE_OFF_MASK;
             /*
              * Allow that the last block exists only partially. The VHDX spec
              * states that the image file can only grow in blocksize increments,
              * but QEMU created images with partial last blocks in the past.
              */
             uint32_t block_length = MIN(s->block_size,
                 bs->total_sectors * BDRV_SECTOR_SIZE - i * s->block_size);
             /*
              * Check for BAT entry overflow.
              */
             if (offset > INT64_MAX - s->block_size) {
                 error_report("VHDX BAT entry %" PRIu64 " offset overflow.", i);
                 ret = -EINVAL;
                 if (!errcnt) {
                     break;
                 }
                 (*errcnt)++;
             }
             /*
              * Check if fully allocated BAT entries do not reside after
              * end of the image file.
              */
             if (offset >= image_file_size) {
                 error_report("VHDX BAT entry %" PRIu64 " start offset %" PRIu64
                              " points after end of file (%" PRIi64 "). Image"
                              " has probably been truncated.",
                              i, offset, image_file_size);
                 ret = -EINVAL;
                 if (!errcnt) {
                     break;
                 }
                 (*errcnt)++;
             } else if (offset + block_length > image_file_size) {
                 error_report("VHDX BAT entry %" PRIu64 " end offset %" PRIu64
                              " points after end of file (%" PRIi64 "). Image"
                              " has probably been truncated.",
                              i, offset + block_length - 1, image_file_size);
                 ret = -EINVAL;
                 if (!errcnt) {
                     break;
                 }
                 (*errcnt)++;
             }
 
             /*
              * verify populated BAT field file offsets against
              * region table and log entries
              */
             if (payblocks--) {
                 /* payload bat entries */
                 int ret2;
                 ret2 = vhdx_region_check(s, offset, s->block_size);
                 if (ret2 < 0) {
                     ret = -EINVAL;
                     if (!errcnt) {
                         break;
                     }
                     (*errcnt)++;
                 }
             } else {
                 payblocks = s->chunk_ratio;
                 /*
                  * Once differencing files are supported, verify sector bitmap
                  * blocks here
                  */
             }
         }
     }
 
     return ret;
 }
 
 static void vhdx_close(BlockDriverState *bs)
 {
     BDRVVHDXState *s = bs->opaque;
     qemu_vfree(s->headers[0]);
     s->headers[0] = NULL;
     qemu_vfree(s->headers[1]);
     s->headers[1] = NULL;
     qemu_vfree(s->bat);
     s->bat = NULL;
     qemu_vfree(s->parent_entries);
     s->parent_entries = NULL;
     migrate_del_blocker(s->migration_blocker);
     error_free(s->migration_blocker);
     qemu_vfree(s->log.hdr);
     s->log.hdr = NULL;
     vhdx_region_unregister_all(s);
 }
 
 static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
 {
     BDRVVHDXState *s = bs->opaque;
     int ret = 0;
     uint32_t i;
     uint64_t signature;
     Error *local_err = NULL;
 
     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
     if (ret < 0) {
         return ret;
     }
 
     s->bat = NULL;
     s->first_visible_write = true;
 
     qemu_co_mutex_init(&s->lock);
     QLIST_INIT(&s->regions);
 
     /* validate the file signature */
     ret = bdrv_pread(bs->file, 0, sizeof(uint64_t), &signature, 0);
     if (ret < 0) {
         goto fail;
     }
     if (memcmp(&signature, "vhdxfile", 8)) {
         ret = -EINVAL;
         goto fail;
     }
 
     /* This is used for any header updates, for the file_write_guid.
      * The spec dictates that a new value should be used for the first
      * header update */
     vhdx_guid_generate(&s->session_guid);
 
     vhdx_parse_header(bs, s, &local_err);
     if (local_err != NULL) {
         error_propagate(errp, local_err);
         ret = -EINVAL;
         goto fail;
     }
 
     ret = vhdx_parse_log(bs, s, &s->log_replayed_on_open, errp);
     if (ret < 0) {
         goto fail;
     }
 
     ret = vhdx_open_region_tables(bs, s);
     if (ret < 0) {
         goto fail;
     }
 
     ret = vhdx_parse_metadata(bs, s);
     if (ret < 0) {
         goto fail;
     }
 
     s->block_size = s->params.block_size;
 
     /* the VHDX spec dictates that virtual_disk_size is always a multiple of
      * logical_sector_size */
     bs->total_sectors = s->virtual_disk_size >> s->logical_sector_size_bits;
 
     vhdx_calc_bat_entries(s);
 
     s->bat_offset = s->bat_rt.file_offset;
 
     if (s->bat_entries > s->bat_rt.length / sizeof(VHDXBatEntry)) {
         /* BAT allocation is not large enough for all entries */
         ret = -EINVAL;
         goto fail;
     }
 
     /* s->bat is freed in vhdx_close() */
     s->bat = qemu_try_blockalign(bs->file->bs, s->bat_rt.length);
     if (s->bat == NULL) {
         ret = -ENOMEM;
         goto fail;
     }
 
     ret = bdrv_pread(bs->file, s->bat_offset, s->bat_rt.length, s->bat, 0);
     if (ret < 0) {
         goto fail;
     }
 
     /* endian convert populated BAT field entires */
     for (i = 0; i < s->bat_entries; i++) {
         s->bat[i] = le64_to_cpu(s->bat[i]);
     }
 
     if (!(flags & BDRV_O_CHECK)) {
         ret = vhdx_check_bat_entries(bs, NULL);
         if (ret < 0) {
             goto fail;
         }
     }
 
     /* Disable migration when VHDX images are used */
     error_setg(&s->migration_blocker, "The vhdx format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
     ret = migrate_add_blocker(s->migration_blocker, errp);
     if (ret < 0) {
         error_free(s->migration_blocker);
         goto fail;
     }
 
     /* TODO: differencing files */
 
     return 0;
 fail:
     vhdx_close(bs);
     return ret;
 }
 
 static int vhdx_reopen_prepare(BDRVReopenState *state,
                                BlockReopenQueue *queue, Error **errp)
 {
     return 0;
 }
 
 
 /*
  * Perform sector to block offset translations, to get various
  * sector and file offsets into the image.  See VHDXSectorInfo
  */
 static void vhdx_block_translate(BDRVVHDXState *s, int64_t sector_num,
                                  int nb_sectors, VHDXSectorInfo *sinfo)
 {
     uint32_t block_offset;
 
     sinfo->bat_idx = sector_num >> s->sectors_per_block_bits;
     /* effectively a modulo - this gives us the offset into the block
      * (in sector sizes) for our sector number */
     block_offset = sector_num - (sinfo->bat_idx << s->sectors_per_block_bits);
     /* the chunk ratio gives us the interleaving of the sector
      * bitmaps, so we need to advance our page block index by the
      * sector bitmaps entry number */
     sinfo->bat_idx += sinfo->bat_idx >> s->chunk_ratio_bits;
 
     /* the number of sectors we can read/write in this cycle */
     sinfo->sectors_avail = s->sectors_per_block - block_offset;
 
     sinfo->bytes_left = sinfo->sectors_avail << s->logical_sector_size_bits;
 
     if (sinfo->sectors_avail > nb_sectors) {
         sinfo->sectors_avail = nb_sectors;
     }
 
     sinfo->bytes_avail = sinfo->sectors_avail << s->logical_sector_size_bits;
 
     sinfo->file_offset = s->bat[sinfo->bat_idx] & VHDX_BAT_FILE_OFF_MASK;
 
     sinfo->block_offset = block_offset << s->logical_sector_size_bits;
 
     /* The file offset must be past the header section, so must be > 0 */
     if (sinfo->file_offset == 0) {
         return;
     }
 
     /* block offset is the offset in vhdx logical sectors, in
      * the payload data block. Convert that to a byte offset
      * in the block, and add in the payload data block offset
      * in the file, in bytes, to get the final read address */
 
     sinfo->file_offset += sinfo->block_offset;
 }
 
 
 static int vhdx_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BDRVVHDXState *s = bs->opaque;
 
     bdi->cluster_size = s->block_size;
 
     return 0;
 }
 
 
 static coroutine_fn int vhdx_co_readv(BlockDriverState *bs, int64_t sector_num,
                                       int nb_sectors, QEMUIOVector *qiov)
 {
     BDRVVHDXState *s = bs->opaque;
     int ret = 0;
     VHDXSectorInfo sinfo;
     uint64_t bytes_done = 0;
     QEMUIOVector hd_qiov;
 
     qemu_iovec_init(&hd_qiov, qiov->niov);
 
     qemu_co_mutex_lock(&s->lock);
 
     while (nb_sectors > 0) {
         /* We are a differencing file, so we need to inspect the sector bitmap
          * to see if we have the data or not */
         if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
             /* not supported yet */
             ret = -ENOTSUP;
             goto exit;
         } else {
             vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
 
             qemu_iovec_reset(&hd_qiov);
             qemu_iovec_concat(&hd_qiov, qiov,  bytes_done, sinfo.bytes_avail);
 
             /* check the payload block state */
             switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) {
             case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
             case PAYLOAD_BLOCK_UNDEFINED:
             case PAYLOAD_BLOCK_UNMAPPED:
             case PAYLOAD_BLOCK_UNMAPPED_v095:
             case PAYLOAD_BLOCK_ZERO:
                 /* return zero */
                 qemu_iovec_memset(&hd_qiov, 0, 0, sinfo.bytes_avail);
                 break;
             case PAYLOAD_BLOCK_FULLY_PRESENT:
                 qemu_co_mutex_unlock(&s->lock);
                 ret = bdrv_co_preadv(bs->file, sinfo.file_offset,
                                      sinfo.sectors_avail * BDRV_SECTOR_SIZE,
                                      &hd_qiov, 0);
                 qemu_co_mutex_lock(&s->lock);
                 if (ret < 0) {
                     goto exit;
                 }
                 break;
             case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
                 /* we don't yet support difference files, fall through
                  * to error */
             default:
                 ret = -EIO;
                 goto exit;
                 break;
             }
             nb_sectors -= sinfo.sectors_avail;
             sector_num += sinfo.sectors_avail;
             bytes_done += sinfo.bytes_avail;
         }
     }
     ret = 0;
 exit:
     qemu_co_mutex_unlock(&s->lock);
     qemu_iovec_destroy(&hd_qiov);
     return ret;
 }
 
 /*
  * Allocate a new payload block at the end of the file.
  *
  * Allocation will happen at 1MB alignment inside the file.
  *
  * If @need_zero is set on entry but not cleared on return, then truncation
  * could not guarantee that the new portion reads as zero, and the caller
  * will take care of it instead.
  *
  * Returns the file offset start of the new payload block
  */
 static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s,
                                uint64_t *new_offset, bool *need_zero)
 {
     int64_t current_len;
 
     current_len = bdrv_getlength(bs->file->bs);
     if (current_len < 0) {
         return current_len;
     }
 
     *new_offset = current_len;
 
     /* per the spec, the address for a block is in units of 1MB */
     *new_offset = ROUND_UP(*new_offset, 1 * MiB);
     if (*new_offset > INT64_MAX) {
         return -EINVAL;
     }
 
     if (*need_zero) {
         int ret;
 
         ret = bdrv_truncate(bs->file, *new_offset + s->block_size, false,
                             PREALLOC_MODE_OFF, BDRV_REQ_ZERO_WRITE, NULL);
         if (ret != -ENOTSUP) {
             *need_zero = false;
             return ret;
         }
     }
 
     return bdrv_truncate(bs->file, *new_offset + s->block_size, false,
                          PREALLOC_MODE_OFF, 0, NULL);
 }
 
 /*
  * Update the BAT table entry with the new file offset, and the new entry
  * state */
 static void vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s,
                                        VHDXSectorInfo *sinfo,
                                        uint64_t *bat_entry_le,
                                        uint64_t *bat_offset, int state)
 {
     /* The BAT entry is a uint64, with 44 bits for the file offset in units of
      * 1MB, and 3 bits for the block state. */
     if ((state == PAYLOAD_BLOCK_ZERO)        ||
         (state == PAYLOAD_BLOCK_UNDEFINED)   ||
         (state == PAYLOAD_BLOCK_NOT_PRESENT) ||
         (state == PAYLOAD_BLOCK_UNMAPPED)) {
         s->bat[sinfo->bat_idx]  = 0;  /* For PAYLOAD_BLOCK_ZERO, the
                                          FileOffsetMB field is denoted as
                                          'reserved' in the v1.0 spec.  If it is
                                          non-zero, MS Hyper-V will fail to read
                                          the disk image */
     } else {
         s->bat[sinfo->bat_idx]  = sinfo->file_offset;
     }
 
     s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK;
 
     *bat_entry_le = cpu_to_le64(s->bat[sinfo->bat_idx]);
     *bat_offset = s->bat_offset + sinfo->bat_idx * sizeof(VHDXBatEntry);
 
 }
 
 /* Per the spec, on the first write of guest-visible data to the file the
  * data write guid must be updated in the header */
 int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s)
 {
     int ret = 0;
     if (s->first_visible_write) {
         s->first_visible_write = false;
         ret = vhdx_update_headers(bs, s, true, NULL);
     }
     return ret;
 }
 
 static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
                                        int nb_sectors, QEMUIOVector *qiov,
                                        int flags)
 {
     int ret = -ENOTSUP;
     BDRVVHDXState *s = bs->opaque;
     VHDXSectorInfo sinfo;
     uint64_t bytes_done = 0;
     uint64_t bat_entry = 0;
     uint64_t bat_entry_offset = 0;
     QEMUIOVector hd_qiov;
     struct iovec iov1 = { 0 };
     struct iovec iov2 = { 0 };
     int sectors_to_write;
     int bat_state;
     uint64_t bat_prior_offset = 0;
     bool bat_update = false;
 
     qemu_iovec_init(&hd_qiov, qiov->niov);
 
     qemu_co_mutex_lock(&s->lock);
 
     ret = vhdx_user_visible_write(bs, s);
     if (ret < 0) {
         goto exit;
     }
 
     while (nb_sectors > 0) {
         bool use_zero_buffers = false;
         bat_update = false;
         if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
             /* not supported yet */
             ret = -ENOTSUP;
             goto exit;
         } else {
             vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
             sectors_to_write = sinfo.sectors_avail;
 
             qemu_iovec_reset(&hd_qiov);
             /* check the payload block state */
             bat_state = s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK;
             switch (bat_state) {
             case PAYLOAD_BLOCK_ZERO:
                 /* in this case, we need to preserve zero writes for
                  * data that is not part of this write, so we must pad
                  * the rest of the buffer to zeroes */
                 use_zero_buffers = true;
                 /* fall through */
             case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
             case PAYLOAD_BLOCK_UNMAPPED:
             case PAYLOAD_BLOCK_UNMAPPED_v095:
             case PAYLOAD_BLOCK_UNDEFINED:
                 bat_prior_offset = sinfo.file_offset;
                 ret = vhdx_allocate_block(bs, s, &sinfo.file_offset,
                                           &use_zero_buffers);
                 if (ret < 0) {
                     goto exit;
                 }
                 /*
                  * once we support differencing files, this may also be
                  * partially present
                  */
                 /* update block state to the newly specified state */
                 vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
                                             &bat_entry_offset,
                                             PAYLOAD_BLOCK_FULLY_PRESENT);
                 bat_update = true;
                 /*
                  * Since we just allocated a block, file_offset is the
                  * beginning of the payload block. It needs to be the
                  * write address, which includes the offset into the
                  * block, unless the entire block needs to read as
                  * zeroes but truncation was not able to provide them,
                  * in which case we need to fill in the rest.
                  */
                 if (!use_zero_buffers) {
                     sinfo.file_offset += sinfo.block_offset;
                 } else {
                     /* zero fill the front, if any */
                     if (sinfo.block_offset) {
                         iov1.iov_len = sinfo.block_offset;
                         iov1.iov_base = qemu_blockalign(bs, iov1.iov_len);
                         memset(iov1.iov_base, 0, iov1.iov_len);
                         qemu_iovec_concat_iov(&hd_qiov, &iov1, 1, 0,
                                               iov1.iov_len);
                         sectors_to_write += iov1.iov_len >> BDRV_SECTOR_BITS;
                     }
 
                     /* our actual data */
                     qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
                                       sinfo.bytes_avail);
 
                     /* zero fill the back, if any */
                     if ((sinfo.bytes_avail - sinfo.block_offset) <
                          s->block_size) {
                         iov2.iov_len = s->block_size -
                                       (sinfo.bytes_avail + sinfo.block_offset);
                         iov2.iov_base = qemu_blockalign(bs, iov2.iov_len);
                         memset(iov2.iov_base, 0, iov2.iov_len);
                         qemu_iovec_concat_iov(&hd_qiov, &iov2, 1, 0,
                                               iov2.iov_len);
                         sectors_to_write += iov2.iov_len >> BDRV_SECTOR_BITS;
                     }
                 }
 
                 /* fall through */
             case PAYLOAD_BLOCK_FULLY_PRESENT:
                 /* if the file offset address is in the header zone,
                  * there is a problem */
                 if (sinfo.file_offset < (1 * MiB)) {
                     ret = -EFAULT;
                     goto error_bat_restore;
                 }
 
                 if (!use_zero_buffers) {
                     qemu_iovec_concat(&hd_qiov, qiov,  bytes_done,
                                       sinfo.bytes_avail);
                 }
                 /* block exists, so we can just overwrite it */
                 qemu_co_mutex_unlock(&s->lock);
                 ret = bdrv_co_pwritev(bs->file, sinfo.file_offset,
                                       sectors_to_write * BDRV_SECTOR_SIZE,
                                       &hd_qiov, 0);
                 qemu_co_mutex_lock(&s->lock);
                 if (ret < 0) {
                     goto error_bat_restore;
                 }
                 break;
             case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
                 /* we don't yet support difference files, fall through
                  * to error */
             default:
                 ret = -EIO;
                 goto exit;
                 break;
             }
 
             if (bat_update) {
                 /* this will update the BAT entry into the log journal, and
                  * then flush the log journal out to disk */
                 ret =  vhdx_log_write_and_flush(bs, s, &bat_entry,
                                                 sizeof(VHDXBatEntry),
                                                 bat_entry_offset);
                 if (ret < 0) {
                     goto exit;
                 }
             }
 
             nb_sectors -= sinfo.sectors_avail;
             sector_num += sinfo.sectors_avail;
             bytes_done += sinfo.bytes_avail;
 
         }
     }
 
     goto exit;
 
 error_bat_restore:
     if (bat_update) {
         /* keep metadata in sync, and restore the bat entry state
          * if error. */
         sinfo.file_offset = bat_prior_offset;
         vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
                                     &bat_entry_offset, bat_state);
     }
 exit:
     qemu_vfree(iov1.iov_base);
     qemu_vfree(iov2.iov_base);
     qemu_co_mutex_unlock(&s->lock);
     qemu_iovec_destroy(&hd_qiov);
     return ret;
 }
 
 
 
 /*
  * Create VHDX Headers
  *
  * There are 2 headers, and the highest sequence number will represent
  * the active header
  */
 static int vhdx_create_new_headers(BlockBackend *blk, uint64_t image_size,
                                    uint32_t log_size)
 {
     BlockDriverState *bs = blk_bs(blk);
     BdrvChild *child;
     int ret = 0;
     VHDXHeader *hdr = NULL;
 
     hdr = g_new0(VHDXHeader, 1);
 
     hdr->signature       = VHDX_HEADER_SIGNATURE;
     hdr->sequence_number = g_random_int();
     hdr->log_version     = 0;
     hdr->version         = 1;
     hdr->log_length      = log_size;
     hdr->log_offset      = VHDX_HEADER_SECTION_END;
     vhdx_guid_generate(&hdr->file_write_guid);
     vhdx_guid_generate(&hdr->data_write_guid);
 
     /* XXX Ugly way to get blk->root, but that's a feature, not a bug. This
      * hack makes it obvious that vhdx_write_header() bypasses the BlockBackend
      * here, which it really shouldn't be doing. */
     child = QLIST_FIRST(&bs->parents);
     assert(!QLIST_NEXT(child, next_parent));
 
     ret = vhdx_write_header(child, hdr, VHDX_HEADER1_OFFSET, false);
     if (ret < 0) {
         goto exit;
     }
     hdr->sequence_number++;
     ret = vhdx_write_header(child, hdr, VHDX_HEADER2_OFFSET, false);
     if (ret < 0) {
         goto exit;
     }
 
 exit:
     g_free(hdr);
     return ret;
 }
 
 #define VHDX_METADATA_ENTRY_BUFFER_SIZE \
                                     (sizeof(VHDXFileParameters)               +\
                                      sizeof(VHDXVirtualDiskSize)              +\
                                      sizeof(VHDXPage83Data)                   +\
                                      sizeof(VHDXVirtualDiskLogicalSectorSize) +\
                                      sizeof(VHDXVirtualDiskPhysicalSectorSize))
 
 /*
  * Create the Metadata entries.
  *
  * For more details on the entries, see section 3.5 (pg 29) in the
  * VHDX 1.00 specification.
  *
  * We support 5 metadata entries (all required by spec):
  *          File Parameters,
  *          Virtual Disk Size,
  *          Page 83 Data,
  *          Logical Sector Size,
  *          Physical Sector Size
  *
  * The first 64KB of the Metadata section is reserved for the metadata
  * header and entries; beyond that, the metadata items themselves reside.
  */
 static int vhdx_create_new_metadata(BlockBackend *blk,
                                     uint64_t image_size,
                                     uint32_t block_size,
                                     uint32_t sector_size,
                                     uint64_t metadata_offset,
                                     VHDXImageType type)
 {
     int ret = 0;
     uint32_t offset = 0;
     void *buffer = NULL;
     void *entry_buffer;
     VHDXMetadataTableHeader *md_table;
     VHDXMetadataTableEntry  *md_table_entry;
 
     /* Metadata entries */
     VHDXFileParameters     *mt_file_params;
     VHDXVirtualDiskSize    *mt_virtual_size;
     VHDXPage83Data         *mt_page83;
     VHDXVirtualDiskLogicalSectorSize  *mt_log_sector_size;
     VHDXVirtualDiskPhysicalSectorSize *mt_phys_sector_size;
 
     entry_buffer = g_malloc0(VHDX_METADATA_ENTRY_BUFFER_SIZE);
 
     mt_file_params = entry_buffer;
     offset += sizeof(VHDXFileParameters);
     mt_virtual_size = entry_buffer + offset;
     offset += sizeof(VHDXVirtualDiskSize);
     mt_page83 = entry_buffer + offset;
     offset += sizeof(VHDXPage83Data);
     mt_log_sector_size = entry_buffer + offset;
     offset += sizeof(VHDXVirtualDiskLogicalSectorSize);
     mt_phys_sector_size = entry_buffer + offset;
 
     mt_file_params->block_size = cpu_to_le32(block_size);
     if (type == VHDX_TYPE_FIXED) {
         mt_file_params->data_bits |= VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED;
         mt_file_params->data_bits = cpu_to_le32(mt_file_params->data_bits);
     }
 
     vhdx_guid_generate(&mt_page83->page_83_data);
     cpu_to_leguids(&mt_page83->page_83_data);
     mt_virtual_size->virtual_disk_size        = cpu_to_le64(image_size);
     mt_log_sector_size->logical_sector_size   = cpu_to_le32(sector_size);
     mt_phys_sector_size->physical_sector_size = cpu_to_le32(sector_size);
 
     buffer = g_malloc0(VHDX_HEADER_BLOCK_SIZE);
     md_table = buffer;
 
     md_table->signature   = VHDX_METADATA_SIGNATURE;
     md_table->entry_count = 5;
     vhdx_metadata_header_le_export(md_table);
 
 
     /* This will reference beyond the reserved table portion */
     offset = 64 * KiB;
 
     md_table_entry = buffer + sizeof(VHDXMetadataTableHeader);
 
     md_table_entry[0].item_id = file_param_guid;
     md_table_entry[0].offset  = offset;
     md_table_entry[0].length  = sizeof(VHDXFileParameters);
     md_table_entry[0].data_bits |= VHDX_META_FLAGS_IS_REQUIRED;
     offset += md_table_entry[0].length;
     vhdx_metadata_entry_le_export(&md_table_entry[0]);
 
     md_table_entry[1].item_id = virtual_size_guid;
     md_table_entry[1].offset  = offset;
     md_table_entry[1].length  = sizeof(VHDXVirtualDiskSize);
     md_table_entry[1].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                    VHDX_META_FLAGS_IS_VIRTUAL_DISK;
     offset += md_table_entry[1].length;
     vhdx_metadata_entry_le_export(&md_table_entry[1]);
 
     md_table_entry[2].item_id = page83_guid;
     md_table_entry[2].offset  = offset;
     md_table_entry[2].length  = sizeof(VHDXPage83Data);
     md_table_entry[2].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                    VHDX_META_FLAGS_IS_VIRTUAL_DISK;
     offset += md_table_entry[2].length;
     vhdx_metadata_entry_le_export(&md_table_entry[2]);
 
     md_table_entry[3].item_id = logical_sector_guid;
     md_table_entry[3].offset  = offset;
     md_table_entry[3].length  = sizeof(VHDXVirtualDiskLogicalSectorSize);
     md_table_entry[3].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                    VHDX_META_FLAGS_IS_VIRTUAL_DISK;
     offset += md_table_entry[3].length;
     vhdx_metadata_entry_le_export(&md_table_entry[3]);
 
     md_table_entry[4].item_id = phys_sector_guid;
     md_table_entry[4].offset  = offset;
     md_table_entry[4].length  = sizeof(VHDXVirtualDiskPhysicalSectorSize);
     md_table_entry[4].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                    VHDX_META_FLAGS_IS_VIRTUAL_DISK;
     vhdx_metadata_entry_le_export(&md_table_entry[4]);
 
     ret = blk_pwrite(blk, metadata_offset, VHDX_HEADER_BLOCK_SIZE, buffer, 0);
     if (ret < 0) {
         goto exit;
     }
 
     ret = blk_pwrite(blk, metadata_offset + (64 * KiB),
                      VHDX_METADATA_ENTRY_BUFFER_SIZE, entry_buffer, 0);
     if (ret < 0) {
         goto exit;
     }
 
 
 exit:
     g_free(buffer);
     g_free(entry_buffer);
     return ret;
 }
 
 /* This create the actual BAT itself.  We currently only support
  * 'Dynamic' and 'Fixed' image types.
  *
  *  Dynamic images: default state of the BAT is all zeroes.
  *
  *  Fixed images: default state of the BAT is fully populated, with
  *                file offsets and state PAYLOAD_BLOCK_FULLY_PRESENT.
  */
 static int vhdx_create_bat(BlockBackend *blk, BDRVVHDXState *s,
                            uint64_t image_size, VHDXImageType type,
                            bool use_zero_blocks, uint64_t file_offset,
                            uint32_t length, Error **errp)
 {
     int ret = 0;
     uint64_t data_file_offset;
     uint64_t total_sectors = 0;
     uint64_t sector_num = 0;
     uint64_t unused;
     int block_state;
     VHDXSectorInfo sinfo;
 
     assert(s->bat == NULL);
 
     /* this gives a data start after BAT/bitmap entries, and well
      * past any metadata entries (with a 4 MB buffer for future
      * expansion */
     data_file_offset = file_offset + length + 5 * MiB;
     total_sectors = image_size >> s->logical_sector_size_bits;
 
     if (type == VHDX_TYPE_DYNAMIC) {
         /* All zeroes, so we can just extend the file - the end of the BAT
          * is the furthest thing we have written yet */
         ret = blk_truncate(blk, data_file_offset, false, PREALLOC_MODE_OFF,
                            0, errp);
         if (ret < 0) {
             goto exit;
         }
     } else if (type == VHDX_TYPE_FIXED) {
         ret = blk_truncate(blk, data_file_offset + image_size, false,
                            PREALLOC_MODE_OFF, 0, errp);
         if (ret < 0) {
             goto exit;
         }
     } else {
         error_setg(errp, "Unsupported image type");
         ret = -ENOTSUP;
         goto exit;
     }
 
     if (type == VHDX_TYPE_FIXED ||
                 use_zero_blocks ||
                 bdrv_has_zero_init(blk_bs(blk)) == 0) {
         /* for a fixed file, the default BAT entry is not zero */
         s->bat = g_try_malloc0(length);
         if (length && s->bat == NULL) {
             error_setg(errp, "Failed to allocate memory for the BAT");
             ret = -ENOMEM;
             goto exit;
         }
         block_state = type == VHDX_TYPE_FIXED ? PAYLOAD_BLOCK_FULLY_PRESENT :
                                                 PAYLOAD_BLOCK_NOT_PRESENT;
         block_state = use_zero_blocks ? PAYLOAD_BLOCK_ZERO : block_state;
         /* fill the BAT by emulating sector writes of sectors_per_block size */
         while (sector_num < total_sectors) {
             vhdx_block_translate(s, sector_num, s->sectors_per_block, &sinfo);
             sinfo.file_offset = data_file_offset +
                                 (sector_num << s->logical_sector_size_bits);
             sinfo.file_offset = ROUND_UP(sinfo.file_offset, MiB);
             vhdx_update_bat_table_entry(blk_bs(blk), s, &sinfo, &unused, &unused,
                                         block_state);
             s->bat[sinfo.bat_idx] = cpu_to_le64(s->bat[sinfo.bat_idx]);
             sector_num += s->sectors_per_block;
         }
         ret = blk_pwrite(blk, file_offset, length, s->bat, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to write the BAT");
             goto exit;
         }
     }
 
 
 
 exit:
     g_free(s->bat);
     return ret;
 }
 
 /* Creates the region table header, and region table entries.
  * There are 2 supported region table entries: BAT, and Metadata/
  *
  * As the calculations for the BAT region table are also needed
  * to create the BAT itself, we will also cause the BAT to be
  * created.
  */
 static int vhdx_create_new_region_table(BlockBackend *blk,
                                         uint64_t image_size,
                                         uint32_t block_size,
                                         uint32_t sector_size,
                                         uint32_t log_size,
                                         bool use_zero_blocks,
                                         VHDXImageType type,
                                         uint64_t *metadata_offset,
                                         Error **errp)
 {
     int ret = 0;
     uint32_t offset = 0;
     void *buffer = NULL;
     uint64_t bat_file_offset;
     uint32_t bat_length;
     BDRVVHDXState *s = NULL;
     VHDXRegionTableHeader *region_table;
     VHDXRegionTableEntry *rt_bat;
     VHDXRegionTableEntry *rt_metadata;
 
     assert(metadata_offset != NULL);
 
     /* Populate enough of the BDRVVHDXState to be able to use the
      * pre-existing BAT calculation, translation, and update functions */
     s = g_new0(BDRVVHDXState, 1);
 
     s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) *
                      (uint64_t) sector_size / (uint64_t) block_size;
 
     s->sectors_per_block = block_size / sector_size;
     s->virtual_disk_size = image_size;
     s->block_size = block_size;
     s->logical_sector_size = sector_size;
 
     vhdx_set_shift_bits(s);
 
     vhdx_calc_bat_entries(s);
 
     /* At this point the VHDX state is populated enough for creation */
 
     /* a single buffer is used so we can calculate the checksum over the
      * entire 64KB block */
     buffer = g_malloc0(VHDX_HEADER_BLOCK_SIZE);
     region_table = buffer;
     offset += sizeof(VHDXRegionTableHeader);
     rt_bat = buffer + offset;
     offset += sizeof(VHDXRegionTableEntry);
     rt_metadata  = buffer + offset;
 
     region_table->signature = VHDX_REGION_SIGNATURE;
     region_table->entry_count = 2;   /* BAT and Metadata */
 
     rt_bat->guid        = bat_guid;
     rt_bat->length      = ROUND_UP(s->bat_entries * sizeof(VHDXBatEntry), MiB);
     rt_bat->file_offset = ROUND_UP(VHDX_HEADER_SECTION_END + log_size, MiB);
     s->bat_offset = rt_bat->file_offset;
 
     rt_metadata->guid        = metadata_guid;
     rt_metadata->file_offset = ROUND_UP(rt_bat->file_offset + rt_bat->length,
                                         MiB);
     rt_metadata->length      = 1 * MiB; /* min size, and more than enough */
     *metadata_offset = rt_metadata->file_offset;
 
     bat_file_offset = rt_bat->file_offset;
     bat_length = rt_bat->length;
 
     vhdx_region_header_le_export(region_table);
     vhdx_region_entry_le_export(rt_bat);
     vhdx_region_entry_le_export(rt_metadata);
 
     vhdx_update_checksum(buffer, VHDX_HEADER_BLOCK_SIZE,
                          offsetof(VHDXRegionTableHeader, checksum));
 
 
     /* The region table gives us the data we need to create the BAT,
      * so do that now */
     ret = vhdx_create_bat(blk, s, image_size, type, use_zero_blocks,
                           bat_file_offset, bat_length, errp);
     if (ret < 0) {
         goto exit;
     }
 
     /* Now write out the region headers to disk */
     ret = blk_pwrite(blk, VHDX_REGION_TABLE_OFFSET, VHDX_HEADER_BLOCK_SIZE,
                      buffer, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to write first region table");
         goto exit;
     }
 
     ret = blk_pwrite(blk, VHDX_REGION_TABLE2_OFFSET, VHDX_HEADER_BLOCK_SIZE,
                      buffer, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to write second region table");
         goto exit;
     }
 
 exit:
     g_free(s);
     g_free(buffer);
     return ret;
 }
 
 /* We need to create the following elements:
  *
  *    .-----------------------------------------------------------------.
  *    |   (A)    |   (B)    |    (C)    |     (D)       |     (E)       |
  *    |  File ID |  Header1 |  Header 2 |  Region Tbl 1 |  Region Tbl 2 |
  *    |          |          |           |               |               |
  *    .-----------------------------------------------------------------.
  *    0         64KB      128KB       192KB           256KB           320KB
  *
  *
  *    .---- ~ ----------- ~ ------------ ~ ---------------- ~ -----------.
  *    |     (F)     |     (G)       |    (H)    |                        |
  *    | Journal Log |  BAT / Bitmap |  Metadata |  .... data ......      |
  *    |             |               |           |                        |
  *    .---- ~ ----------- ~ ------------ ~ ---------------- ~ -----------.
  *   1MB
  */
 static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
                                        Error **errp)
 {
     BlockdevCreateOptionsVhdx *vhdx_opts;
     BlockBackend *blk = NULL;
     BlockDriverState *bs = NULL;
 
     int ret = 0;
     uint64_t image_size;
     uint32_t log_size;
     uint32_t block_size;
     uint64_t signature;
     uint64_t metadata_offset;
     bool use_zero_blocks = false;
 
     gunichar2 *creator = NULL;
     glong creator_items;
     VHDXImageType image_type;
 
     assert(opts->driver == BLOCKDEV_DRIVER_VHDX);
     vhdx_opts = &opts->u.vhdx;
 
     /* Validate options and set default values */
     image_size = vhdx_opts->size;
     if (image_size > VHDX_MAX_IMAGE_SIZE) {
         error_setg(errp, "Image size too large; max of 64TB");
         return -EINVAL;
     }
 
     if (!vhdx_opts->has_log_size) {
         log_size = DEFAULT_LOG_SIZE;
     } else {
         if (vhdx_opts->log_size > UINT32_MAX) {
             error_setg(errp, "Log size must be smaller than 4 GB");
             return -EINVAL;
         }
         log_size = vhdx_opts->log_size;
     }
     if (log_size < MiB || (log_size % MiB) != 0) {
         error_setg(errp, "Log size must be a multiple of 1 MB");
         return -EINVAL;
     }
 
     if (!vhdx_opts->has_block_state_zero) {
         use_zero_blocks = true;
     } else {
         use_zero_blocks = vhdx_opts->block_state_zero;
     }
 
     if (!vhdx_opts->has_subformat) {
         vhdx_opts->subformat = BLOCKDEV_VHDX_SUBFORMAT_DYNAMIC;
     }
 
     switch (vhdx_opts->subformat) {
     case BLOCKDEV_VHDX_SUBFORMAT_DYNAMIC:
         image_type = VHDX_TYPE_DYNAMIC;
         break;
     case BLOCKDEV_VHDX_SUBFORMAT_FIXED:
         image_type = VHDX_TYPE_FIXED;
         break;
     default:
         g_assert_not_reached();
     }
 
     /* These are pretty arbitrary, and mainly designed to keep the BAT
      * size reasonable to load into RAM */
     if (vhdx_opts->has_block_size) {
         block_size = vhdx_opts->block_size;
     } else {
         if (image_size > 32 * TiB) {
             block_size = 64 * MiB;
         } else if (image_size > (uint64_t) 100 * GiB) {
             block_size = 32 * MiB;
         } else if (image_size > 1 * GiB) {
             block_size = 16 * MiB;
         } else {
             block_size = 8 * MiB;
         }
     }
 
     if (block_size < MiB || (block_size % MiB) != 0) {
         error_setg(errp, "Block size must be a multiple of 1 MB");
         return -EINVAL;
     }
     if (!is_power_of_2(block_size)) {
         error_setg(errp, "Block size must be a power of two");
         return -EINVAL;
     }
     if (block_size > VHDX_BLOCK_SIZE_MAX) {
         error_setg(errp, "Block size must not exceed %" PRId64,
                    VHDX_BLOCK_SIZE_MAX);
         return -EINVAL;
     }
 
     /* Create BlockBackend to write to the image */
     bs = bdrv_open_blockdev_ref(vhdx_opts->file, errp);
     if (bs == NULL) {
         return -EIO;
     }
 
     blk = blk_new_with_bs(bs, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL,
                           errp);
     if (!blk) {
         ret = -EPERM;
         goto delete_and_exit;
     }
     blk_set_allow_write_beyond_eof(blk, true);
 
     /* Create (A) */
 
     /* The creator field is optional, but may be useful for
      * debugging / diagnostics */
     creator = g_utf8_to_utf16("QEMU v" QEMU_VERSION, -1, NULL,
                               &creator_items, NULL);
     signature = cpu_to_le64(VHDX_FILE_SIGNATURE);
     ret = blk_co_pwrite(blk, VHDX_FILE_ID_OFFSET, sizeof(signature), &signature,
                         0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to write file signature");
         goto delete_and_exit;
     }
     if (creator) {
         ret = blk_co_pwrite(blk, VHDX_FILE_ID_OFFSET + sizeof(signature),
                             creator_items * sizeof(gunichar2), creator, 0);
         if (ret < 0) {
             error_setg_errno(errp, -ret, "Failed to write creator field");
             goto delete_and_exit;
         }
     }
 
 
     /* Creates (B),(C) */
     ret = vhdx_create_new_headers(blk, image_size, log_size);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to write image headers");
         goto delete_and_exit;
     }
 
     /* Creates (D),(E),(G) explicitly. (F) created as by-product */
     ret = vhdx_create_new_region_table(blk, image_size, block_size, 512,
                                        log_size, use_zero_blocks, image_type,
                                        &metadata_offset, errp);
     if (ret < 0) {
         goto delete_and_exit;
     }
 
     /* Creates (H) */
     ret = vhdx_create_new_metadata(blk, image_size, block_size, 512,
                                    metadata_offset, image_type);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Failed to initialize metadata");
         goto delete_and_exit;
     }
 
     ret = 0;
 delete_and_exit:
     blk_unref(blk);
     bdrv_unref(bs);
     g_free(creator);
     return ret;
 }
 
 static int coroutine_fn vhdx_co_create_opts(BlockDriver *drv,
                                             const char *filename,
                                             QemuOpts *opts,
                                             Error **errp)
 {
     BlockdevCreateOptions *create_options = NULL;
     QDict *qdict;
     Visitor *v;
     BlockDriverState *bs = NULL;
     int ret;
 
     static const QDictRenames opt_renames[] = {
         { VHDX_BLOCK_OPT_LOG_SIZE,      "log-size" },
         { VHDX_BLOCK_OPT_BLOCK_SIZE,    "block-size" },
         { VHDX_BLOCK_OPT_ZERO,          "block-state-zero" },
         { NULL, NULL },
     };
 
     /* Parse options and convert legacy syntax */
     qdict = qemu_opts_to_qdict_filtered(opts, NULL, &vhdx_create_opts, true);
 
     if (!qdict_rename_keys(qdict, opt_renames, errp)) {
         ret = -EINVAL;
         goto fail;
     }
 
     /* Create and open the file (protocol layer) */
     ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
         goto fail;
     }
 
     bs = bdrv_open(filename, NULL, NULL,
                    BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
     if (bs == NULL) {
         ret = -EIO;
         goto fail;
     }
 
     /* Now get the QAPI type BlockdevCreateOptions */
     qdict_put_str(qdict, "driver", "vhdx");
     qdict_put_str(qdict, "file", bs->node_name);
 
     v = qobject_input_visitor_new_flat_confused(qdict, errp);
     if (!v) {
         ret = -EINVAL;
         goto fail;
     }
 
     visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
     visit_free(v);
     if (!create_options) {
         ret = -EINVAL;
         goto fail;
     }
 
     /* Silently round up sizes:
      * The image size is rounded to 512 bytes. Make the block and log size
      * close to what was specified, but must be at least 1MB, and a multiple of
      * 1 MB. Also respect VHDX_BLOCK_SIZE_MAX for block sizes. block_size = 0
      * means auto, which is represented by a missing key in QAPI. */
     assert(create_options->driver == BLOCKDEV_DRIVER_VHDX);
     create_options->u.vhdx.size =
         ROUND_UP(create_options->u.vhdx.size, BDRV_SECTOR_SIZE);
 
     if (create_options->u.vhdx.has_log_size) {
         create_options->u.vhdx.log_size =
             ROUND_UP(create_options->u.vhdx.log_size, MiB);
     }
     if (create_options->u.vhdx.has_block_size) {
         create_options->u.vhdx.block_size =
             ROUND_UP(create_options->u.vhdx.block_size, MiB);
 
         if (create_options->u.vhdx.block_size == 0) {
             create_options->u.vhdx.has_block_size = false;
         }
         if (create_options->u.vhdx.block_size > VHDX_BLOCK_SIZE_MAX) {
             create_options->u.vhdx.block_size = VHDX_BLOCK_SIZE_MAX;
         }
     }
 
     /* Create the vhdx image (format layer) */
     ret = vhdx_co_create(create_options, errp);
 
 fail:
     qobject_unref(qdict);
     bdrv_unref(bs);
     qapi_free_BlockdevCreateOptions(create_options);
     return ret;
 }
 
 /* If opened r/w, the VHDX driver will automatically replay the log,
  * if one is present, inside the vhdx_open() call.
  *
  * If qemu-img check -r all is called, the image is automatically opened
  * r/w and any log has already been replayed, so there is nothing (currently)
  * for us to do here
  */
 static int coroutine_fn vhdx_co_check(BlockDriverState *bs,
                                       BdrvCheckResult *result,
                                       BdrvCheckMode fix)
 {
     BDRVVHDXState *s = bs->opaque;
 
     if (s->log_replayed_on_open) {
         result->corruptions_fixed++;
     }
 
     vhdx_check_bat_entries(bs, &result->corruptions);
 
     return 0;
 }
 
 static int vhdx_has_zero_init(BlockDriverState *bs)
 {
     BDRVVHDXState *s = bs->opaque;
     int state;
 
     /*
      * Check the subformat: Fixed images have all BAT entries present,
      * dynamic images have none (right after creation).  It is
      * therefore enough to check the first BAT entry.
      */
     if (!s->bat_entries) {
         return 1;
     }
 
     state = s->bat[0] & VHDX_BAT_STATE_BIT_MASK;
     if (state == PAYLOAD_BLOCK_FULLY_PRESENT) {
         /* Fixed subformat */
         return bdrv_has_zero_init(bs->file->bs);
     }
 
     /* Dynamic subformat */
     return 1;
 }
 
 static QemuOptsList vhdx_create_opts = {
     .name = "vhdx-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(vhdx_create_opts.head),
     .desc = {
         {
            .name = BLOCK_OPT_SIZE,
            .type = QEMU_OPT_SIZE,
            .help = "Virtual disk size; max of 64TB."
        },
        {
            .name = VHDX_BLOCK_OPT_LOG_SIZE,
            .type = QEMU_OPT_SIZE,
            .def_value_str = stringify(DEFAULT_LOG_SIZE),
            .help = "Log size; min 1MB."
        },
        {
            .name = VHDX_BLOCK_OPT_BLOCK_SIZE,
            .type = QEMU_OPT_SIZE,
            .def_value_str = stringify(0),
            .help = "Block Size; min 1MB, max 256MB. "
                    "0 means auto-calculate based on image size."
        },
        {
            .name = BLOCK_OPT_SUBFMT,
            .type = QEMU_OPT_STRING,
            .help = "VHDX format type, can be either 'dynamic' or 'fixed'. "
                    "Default is 'dynamic'."
        },
        {
            .name = VHDX_BLOCK_OPT_ZERO,
            .type = QEMU_OPT_BOOL,
            .help = "Force use of payload blocks of type 'ZERO'. "
                    "Non-standard, but default.  Do not set to 'off' when "
                    "using 'qemu-img convert' with subformat=dynamic."
        },
        { NULL }
     }
 };
 
 static BlockDriver bdrv_vhdx = {
     .format_name            = "vhdx",
     .instance_size          = sizeof(BDRVVHDXState),
     .bdrv_probe             = vhdx_probe,
     .bdrv_open              = vhdx_open,
     .bdrv_close             = vhdx_close,
     .bdrv_reopen_prepare    = vhdx_reopen_prepare,
     .bdrv_child_perm        = bdrv_default_perms,
     .bdrv_co_readv          = vhdx_co_readv,
     .bdrv_co_writev         = vhdx_co_writev,
     .bdrv_co_create         = vhdx_co_create,
     .bdrv_co_create_opts    = vhdx_co_create_opts,
     .bdrv_get_info          = vhdx_get_info,
     .bdrv_co_check          = vhdx_co_check,
     .bdrv_has_zero_init     = vhdx_has_zero_init,
 
     .is_format              = true,
     .create_opts            = &vhdx_create_opts,
 };
 
 static void bdrv_vhdx_init(void)
 {
     bdrv_register(&bdrv_vhdx);
 }
 
 block_init(bdrv_vhdx_init);