qemu

block-common.h (17271B)

---

 /*
  * QEMU System Emulator block driver
  *
  * Copyright (c) 2003 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.
  */
 #ifndef BLOCK_COMMON_H
 #define BLOCK_COMMON_H
 
 #include "block/aio.h"
 #include "block/aio-wait.h"
 #include "qemu/iov.h"
 #include "qemu/coroutine.h"
 #include "block/accounting.h"
 #include "block/dirty-bitmap.h"
 #include "block/blockjob.h"
 #include "qemu/hbitmap.h"
 #include "qemu/transactions.h"
 
 /*
  * generated_co_wrapper
  *
  * Function specifier, which does nothing but mark functions to be
  * generated by scripts/block-coroutine-wrapper.py
  *
  * Read more in docs/devel/block-coroutine-wrapper.rst
  */
 #define generated_co_wrapper
 
 /* block.c */
 typedef struct BlockDriver BlockDriver;
 typedef struct BdrvChild BdrvChild;
 typedef struct BdrvChildClass BdrvChildClass;
 
 typedef struct BlockDriverInfo {
     /* in bytes, 0 if irrelevant */
     int cluster_size;
     /* offset at which the VM state can be saved (0 if not possible) */
     int64_t vm_state_offset;
     bool is_dirty;
     /*
      * True if this block driver only supports compressed writes
      */
     bool needs_compressed_writes;
 } BlockDriverInfo;
 
 typedef struct BlockFragInfo {
     uint64_t allocated_clusters;
     uint64_t total_clusters;
     uint64_t fragmented_clusters;
     uint64_t compressed_clusters;
 } BlockFragInfo;
 
 typedef enum {
     BDRV_REQ_COPY_ON_READ       = 0x1,
     BDRV_REQ_ZERO_WRITE         = 0x2,
 
     /*
      * The BDRV_REQ_MAY_UNMAP flag is used in write_zeroes requests to indicate
      * that the block driver should unmap (discard) blocks if it is guaranteed
      * that the result will read back as zeroes. The flag is only passed to the
      * driver if the block device is opened with BDRV_O_UNMAP.
      */
     BDRV_REQ_MAY_UNMAP          = 0x4,
 
     /*
      * An optimization hint when all QEMUIOVector elements are within
      * previously registered bdrv_register_buf() memory ranges.
      *
      * Code that replaces the user's QEMUIOVector elements with bounce buffers
      * must take care to clear this flag.
      */
     BDRV_REQ_REGISTERED_BUF     = 0x8,
 
     BDRV_REQ_FUA                = 0x10,
     BDRV_REQ_WRITE_COMPRESSED   = 0x20,
 
     /*
      * Signifies that this write request will not change the visible disk
      * content.
      */
     BDRV_REQ_WRITE_UNCHANGED    = 0x40,
 
     /*
      * Forces request serialisation. Use only with write requests.
      */
     BDRV_REQ_SERIALISING        = 0x80,
 
     /*
      * Execute the request only if the operation can be offloaded or otherwise
      * be executed efficiently, but return an error instead of using a slow
      * fallback.
      */
     BDRV_REQ_NO_FALLBACK        = 0x100,
 
     /*
      * BDRV_REQ_PREFETCH makes sense only in the context of copy-on-read
      * (i.e., together with the BDRV_REQ_COPY_ON_READ flag or when a COR
      * filter is involved), in which case it signals that the COR operation
      * need not read the data into memory (qiov) but only ensure they are
      * copied to the top layer (i.e., that COR operation is done).
      */
     BDRV_REQ_PREFETCH  = 0x200,
 
     /*
      * If we need to wait for other requests, just fail immediately. Used
      * only together with BDRV_REQ_SERIALISING. Used only with requests aligned
      * to request_alignment (corresponding assertions are in block/io.c).
      */
     BDRV_REQ_NO_WAIT = 0x400,
 
     /* Mask of valid flags */
     BDRV_REQ_MASK               = 0x7ff,
 } BdrvRequestFlags;
 
 #define BDRV_O_NO_SHARE    0x0001 /* don't share permissions */
 #define BDRV_O_RDWR        0x0002
 #define BDRV_O_RESIZE      0x0004 /* request permission for resizing the node */
 #define BDRV_O_SNAPSHOT    0x0008 /* open the file read only and save
                                      writes in a snapshot */
 #define BDRV_O_TEMPORARY   0x0010 /* delete the file after use */
 #define BDRV_O_NOCACHE     0x0020 /* do not use the host page cache */
 #define BDRV_O_NATIVE_AIO  0x0080 /* use native AIO instead of the
                                      thread pool */
 #define BDRV_O_NO_BACKING  0x0100 /* don't open the backing file */
 #define BDRV_O_NO_FLUSH    0x0200 /* disable flushing on this disk */
 #define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
 #define BDRV_O_INACTIVE    0x0800  /* consistency hint for migration handoff */
 #define BDRV_O_CHECK       0x1000  /* open solely for consistency check */
 #define BDRV_O_ALLOW_RDWR  0x2000  /* allow reopen to change from r/o to r/w */
 #define BDRV_O_UNMAP       0x4000  /* execute guest UNMAP/TRIM operations */
 #define BDRV_O_PROTOCOL    0x8000  /* if no block driver is explicitly given:
                                       select an appropriate protocol driver,
                                       ignoring the format layer */
 #define BDRV_O_NO_IO       0x10000 /* don't initialize for I/O */
 #define BDRV_O_AUTO_RDONLY 0x20000 /* degrade to read-only if opening
                                       read-write fails */
 #define BDRV_O_IO_URING    0x40000 /* use io_uring instead of the thread pool */
 
 #define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_NO_FLUSH)
 
 
 /* Option names of options parsed by the block layer */
 
 #define BDRV_OPT_CACHE_WB       "cache.writeback"
 #define BDRV_OPT_CACHE_DIRECT   "cache.direct"
 #define BDRV_OPT_CACHE_NO_FLUSH "cache.no-flush"
 #define BDRV_OPT_READ_ONLY      "read-only"
 #define BDRV_OPT_AUTO_READ_ONLY "auto-read-only"
 #define BDRV_OPT_DISCARD        "discard"
 #define BDRV_OPT_FORCE_SHARE    "force-share"
 
 
 #define BDRV_SECTOR_BITS   9
 #define BDRV_SECTOR_SIZE   (1ULL << BDRV_SECTOR_BITS)
 
 #define BDRV_REQUEST_MAX_SECTORS MIN_CONST(SIZE_MAX >> BDRV_SECTOR_BITS, \
                                            INT_MAX >> BDRV_SECTOR_BITS)
 #define BDRV_REQUEST_MAX_BYTES (BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS)
 
 /*
  * We want allow aligning requests and disk length up to any 32bit alignment
  * and don't afraid of overflow.
  * To achieve it, and in the same time use some pretty number as maximum disk
  * size, let's define maximum "length" (a limit for any offset/bytes request and
  * for disk size) to be the greatest power of 2 less than INT64_MAX.
  */
 #define BDRV_MAX_ALIGNMENT (1L << 30)
 #define BDRV_MAX_LENGTH (QEMU_ALIGN_DOWN(INT64_MAX, BDRV_MAX_ALIGNMENT))
 
 /*
  * Allocation status flags for bdrv_block_status() and friends.
  *
  * Public flags:
  * BDRV_BLOCK_DATA: allocation for data at offset is tied to this layer
  * BDRV_BLOCK_ZERO: offset reads as zero
  * BDRV_BLOCK_OFFSET_VALID: an associated offset exists for accessing raw data
  * BDRV_BLOCK_ALLOCATED: the content of the block is determined by this
  *                       layer rather than any backing, set by block layer
  * BDRV_BLOCK_EOF: the returned pnum covers through end of file for this
  *                 layer, set by block layer
  *
  * Internal flags:
  * BDRV_BLOCK_RAW: for use by passthrough drivers, such as raw, to request
  *                 that the block layer recompute the answer from the returned
  *                 BDS; must be accompanied by just BDRV_BLOCK_OFFSET_VALID.
  * BDRV_BLOCK_RECURSE: request that the block layer will recursively search for
  *                     zeroes in file child of current block node inside
  *                     returned region. Only valid together with both
  *                     BDRV_BLOCK_DATA and BDRV_BLOCK_OFFSET_VALID. Should not
  *                     appear with BDRV_BLOCK_ZERO.
  *
  * If BDRV_BLOCK_OFFSET_VALID is set, the map parameter represents the
  * host offset within the returned BDS that is allocated for the
  * corresponding raw guest data.  However, whether that offset
  * actually contains data also depends on BDRV_BLOCK_DATA, as follows:
  *
  * DATA ZERO OFFSET_VALID
  *  t    t        t       sectors read as zero, returned file is zero at offset
  *  t    f        t       sectors read as valid from file at offset
  *  f    t        t       sectors preallocated, read as zero, returned file not
  *                        necessarily zero at offset
  *  f    f        t       sectors preallocated but read from backing_hd,
  *                        returned file contains garbage at offset
  *  t    t        f       sectors preallocated, read as zero, unknown offset
  *  t    f        f       sectors read from unknown file or offset
  *  f    t        f       not allocated or unknown offset, read as zero
  *  f    f        f       not allocated or unknown offset, read from backing_hd
  */
 #define BDRV_BLOCK_DATA         0x01
 #define BDRV_BLOCK_ZERO         0x02
 #define BDRV_BLOCK_OFFSET_VALID 0x04
 #define BDRV_BLOCK_RAW          0x08
 #define BDRV_BLOCK_ALLOCATED    0x10
 #define BDRV_BLOCK_EOF          0x20
 #define BDRV_BLOCK_RECURSE      0x40
 
 typedef QTAILQ_HEAD(BlockReopenQueue, BlockReopenQueueEntry) BlockReopenQueue;
 
 typedef struct BDRVReopenState {
     BlockDriverState *bs;
     int flags;
     BlockdevDetectZeroesOptions detect_zeroes;
     bool backing_missing;
     BlockDriverState *old_backing_bs; /* keep pointer for permissions update */
     BlockDriverState *old_file_bs; /* keep pointer for permissions update */
     QDict *options;
     QDict *explicit_options;
     void *opaque;
 } BDRVReopenState;
 
 /*
  * Block operation types
  */
 typedef enum BlockOpType {
     BLOCK_OP_TYPE_BACKUP_SOURCE,
     BLOCK_OP_TYPE_BACKUP_TARGET,
     BLOCK_OP_TYPE_CHANGE,
     BLOCK_OP_TYPE_COMMIT_SOURCE,
     BLOCK_OP_TYPE_COMMIT_TARGET,
     BLOCK_OP_TYPE_DATAPLANE,
     BLOCK_OP_TYPE_DRIVE_DEL,
     BLOCK_OP_TYPE_EJECT,
     BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT,
     BLOCK_OP_TYPE_INTERNAL_SNAPSHOT,
     BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
     BLOCK_OP_TYPE_MIRROR_SOURCE,
     BLOCK_OP_TYPE_MIRROR_TARGET,
     BLOCK_OP_TYPE_RESIZE,
     BLOCK_OP_TYPE_STREAM,
     BLOCK_OP_TYPE_REPLACE,
     BLOCK_OP_TYPE_MAX,
 } BlockOpType;
 
 /* Block node permission constants */
 enum {
     /**
      * A user that has the "permission" of consistent reads is guaranteed that
      * their view of the contents of the block device is complete and
      * self-consistent, representing the contents of a disk at a specific
      * point.
      *
      * For most block devices (including their backing files) this is true, but
      * the property cannot be maintained in a few situations like for
      * intermediate nodes of a commit block job.
      */
     BLK_PERM_CONSISTENT_READ    = 0x01,
 
     /** This permission is required to change the visible disk contents. */
     BLK_PERM_WRITE              = 0x02,
 
     /**
      * This permission (which is weaker than BLK_PERM_WRITE) is both enough and
      * required for writes to the block node when the caller promises that
      * the visible disk content doesn't change.
      *
      * As the BLK_PERM_WRITE permission is strictly stronger, either is
      * sufficient to perform an unchanging write.
      */
     BLK_PERM_WRITE_UNCHANGED    = 0x04,
 
     /** This permission is required to change the size of a block node. */
     BLK_PERM_RESIZE             = 0x08,
 
     /**
      * There was a now-removed bit BLK_PERM_GRAPH_MOD, with value of 0x10. QEMU
      * 6.1 and earlier may still lock the corresponding byte in block/file-posix
      * locking.  So, implementing some new permission should be very careful to
      * not interfere with this old unused thing.
      */
 
     BLK_PERM_ALL                = 0x0f,
 
     DEFAULT_PERM_PASSTHROUGH    = BLK_PERM_CONSISTENT_READ
                                  | BLK_PERM_WRITE
                                  | BLK_PERM_WRITE_UNCHANGED
                                  | BLK_PERM_RESIZE,
 
     DEFAULT_PERM_UNCHANGED      = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
 };
 
 /*
  * Flags that parent nodes assign to child nodes to specify what kind of
  * role(s) they take.
  *
  * At least one of DATA, METADATA, FILTERED, or COW must be set for
  * every child.
  *
  *
  * = Connection with bs->children, bs->file and bs->backing fields =
  *
  * 1. Filters
  *
  * Filter drivers have drv->is_filter = true.
  *
  * Filter node has exactly one FILTERED|PRIMARY child, and may have other
  * children which must not have these bits (one example is the
  * copy-before-write filter, which also has its target DATA child).
  *
  * Filter nodes never have COW children.
  *
  * For most filters, the filtered child is linked in bs->file, bs->backing is
  * NULL.  For some filters (as an exception), it is the other way around; those
  * drivers will have drv->filtered_child_is_backing set to true (see that
  * field’s documentation for what drivers this concerns)
  *
  * 2. "raw" driver (block/raw-format.c)
  *
  * Formally it's not a filter (drv->is_filter = false)
  *
  * bs->backing is always NULL
  *
  * Only has one child, linked in bs->file. Its role is either FILTERED|PRIMARY
  * (like filter) or DATA|PRIMARY depending on options.
  *
  * 3. Other drivers
  *
  * Don't have any FILTERED children.
  *
  * May have at most one COW child. In this case it's linked in bs->backing.
  * Otherwise bs->backing is NULL. COW child is never PRIMARY.
  *
  * May have at most one PRIMARY child. In this case it's linked in bs->file.
  * Otherwise bs->file is NULL.
  *
  * May also have some other children that don't have the PRIMARY or COW bit set.
  */
 enum BdrvChildRoleBits {
     /*
      * This child stores data.
      * Any node may have an arbitrary number of such children.
      */
     BDRV_CHILD_DATA         = (1 << 0),
 
     /*
      * This child stores metadata.
      * Any node may have an arbitrary number of metadata-storing
      * children.
      */
     BDRV_CHILD_METADATA     = (1 << 1),
 
     /*
      * A child that always presents exactly the same visible data as
      * the parent, e.g. by virtue of the parent forwarding all reads
      * and writes.
      * This flag is mutually exclusive with DATA, METADATA, and COW.
      * Any node may have at most one filtered child at a time.
      */
     BDRV_CHILD_FILTERED     = (1 << 2),
 
     /*
      * Child from which to read all data that isn't allocated in the
      * parent (i.e., the backing child); such data is copied to the
      * parent through COW (and optionally COR).
      * This field is mutually exclusive with DATA, METADATA, and
      * FILTERED.
      * Any node may have at most one such backing child at a time.
      */
     BDRV_CHILD_COW          = (1 << 3),
 
     /*
      * The primary child.  For most drivers, this is the child whose
      * filename applies best to the parent node.
      * Any node may have at most one primary child at a time.
      */
     BDRV_CHILD_PRIMARY      = (1 << 4),
 
     /* Useful combination of flags */
     BDRV_CHILD_IMAGE        = BDRV_CHILD_DATA
                               | BDRV_CHILD_METADATA
                               | BDRV_CHILD_PRIMARY,
 };
 
 /* Mask of BdrvChildRoleBits values */
 typedef unsigned int BdrvChildRole;
 
 typedef struct BdrvCheckResult {
     int corruptions;
     int leaks;
     int check_errors;
     int corruptions_fixed;
     int leaks_fixed;
     int64_t image_end_offset;
     BlockFragInfo bfi;
 } BdrvCheckResult;
 
 typedef enum {
     BDRV_FIX_LEAKS    = 1,
     BDRV_FIX_ERRORS   = 2,
 } BdrvCheckMode;
 
 typedef struct BlockSizes {
     uint32_t phys;
     uint32_t log;
 } BlockSizes;
 
 typedef struct HDGeometry {
     uint32_t heads;
     uint32_t sectors;
     uint32_t cylinders;
 } HDGeometry;
 
 /*
  * Common functions that are neither I/O nor Global State.
  *
  * These functions must never call any function from other categories
  * (I/O, "I/O or GS", Global State) except this one, but can be invoked by
  * all of them.
  */
 
 char *bdrv_perm_names(uint64_t perm);
 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm);
 
 void bdrv_init_with_whitelist(void);
 bool bdrv_uses_whitelist(void);
 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only);
 
 int bdrv_parse_aio(const char *mode, int *flags);
 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough);
 int bdrv_parse_discard_flags(const char *mode, int *flags);
 
 int path_has_protocol(const char *path);
 int path_is_absolute(const char *path);
 char *path_combine(const char *base_path, const char *filename);
 
 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
                                                    const char *backing,
                                                    Error **errp);
 
 #endif /* BLOCK_COMMON_H */