/* * 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_INT_COMMON_H #define BLOCK_INT_COMMON_H #include "block/accounting.h" #include "block/block.h" #include "block/aio-wait.h" #include "qemu/queue.h" #include "qemu/coroutine.h" #include "qemu/stats64.h" #include "qemu/timer.h" #include "qemu/hbitmap.h" #include "block/snapshot.h" #include "qemu/throttle.h" #include "qemu/rcu.h" #define BLOCK_FLAG_LAZY_REFCOUNTS 8 #define BLOCK_OPT_SIZE "size" #define BLOCK_OPT_ENCRYPT "encryption" #define BLOCK_OPT_ENCRYPT_FORMAT "encrypt.format" #define BLOCK_OPT_COMPAT6 "compat6" #define BLOCK_OPT_HWVERSION "hwversion" #define BLOCK_OPT_BACKING_FILE "backing_file" #define BLOCK_OPT_BACKING_FMT "backing_fmt" #define BLOCK_OPT_CLUSTER_SIZE "cluster_size" #define BLOCK_OPT_TABLE_SIZE "table_size" #define BLOCK_OPT_PREALLOC "preallocation" #define BLOCK_OPT_SUBFMT "subformat" #define BLOCK_OPT_COMPAT_LEVEL "compat" #define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts" #define BLOCK_OPT_ADAPTER_TYPE "adapter_type" #define BLOCK_OPT_REDUNDANCY "redundancy" #define BLOCK_OPT_NOCOW "nocow" #define BLOCK_OPT_EXTENT_SIZE_HINT "extent_size_hint" #define BLOCK_OPT_OBJECT_SIZE "object_size" #define BLOCK_OPT_REFCOUNT_BITS "refcount_bits" #define BLOCK_OPT_DATA_FILE "data_file" #define BLOCK_OPT_DATA_FILE_RAW "data_file_raw" #define BLOCK_OPT_COMPRESSION_TYPE "compression_type" #define BLOCK_OPT_EXTL2 "extended_l2" #define BLOCK_PROBE_BUF_SIZE 512 enum BdrvTrackedRequestType { BDRV_TRACKED_READ, BDRV_TRACKED_WRITE, BDRV_TRACKED_DISCARD, BDRV_TRACKED_TRUNCATE, }; /* * That is not quite good that BdrvTrackedRequest structure is public, * as block/io.c is very careful about incoming offset/bytes being * correct. Be sure to assert bdrv_check_request() succeeded after any * modification of BdrvTrackedRequest object out of block/io.c */ typedef struct BdrvTrackedRequest { BlockDriverState *bs; int64_t offset; int64_t bytes; enum BdrvTrackedRequestType type; bool serialising; int64_t overlap_offset; int64_t overlap_bytes; QLIST_ENTRY(BdrvTrackedRequest) list; Coroutine *co; /* owner, used for deadlock detection */ CoQueue wait_queue; /* coroutines blocked on this request */ struct BdrvTrackedRequest *waiting_for; } BdrvTrackedRequest; struct BlockDriver { /* * These fields are initialized when this object is created, * and are never changed afterwards. */ const char *format_name; int instance_size; /* * Set to true if the BlockDriver is a block filter. Block filters pass * certain callbacks that refer to data (see block.c) to their bs->file * or bs->backing (whichever one exists) if the driver doesn't implement * them. Drivers that do not wish to forward must implement them and return * -ENOTSUP. * Note that filters are not allowed to modify data. * * Filters generally cannot have more than a single filtered child, * because the data they present must at all times be the same as * that on their filtered child. That would be impossible to * achieve for multiple filtered children. * (And this filtered child must then be bs->file or bs->backing.) */ bool is_filter; /* * Only make sense for filter drivers, for others must be false. * If true, filtered child is bs->backing. Otherwise it's bs->file. * Two internal filters use bs->backing as filtered child and has this * field set to true: mirror_top and commit_top. There also two such test * filters in tests/unit/test-bdrv-graph-mod.c. * * Never create any more such filters! * * TODO: imagine how to deprecate this behavior and make all filters work * similarly using bs->file as filtered child. */ bool filtered_child_is_backing; /* * Set to true if the BlockDriver is a format driver. Format nodes * generally do not expect their children to be other format nodes * (except for backing files), and so format probing is disabled * on those children. */ bool is_format; /* * Drivers not implementing bdrv_parse_filename nor bdrv_open should have * this field set to true, except ones that are defined only by their * child's bs. * An example of the last type will be the quorum block driver. */ bool bdrv_needs_filename; /* * Set if a driver can support backing files. This also implies the * following semantics: * * - Return status 0 of .bdrv_co_block_status means that corresponding * blocks are not allocated in this layer of backing-chain * - For such (unallocated) blocks, read will: * - fill buffer with zeros if there is no backing file * - read from the backing file otherwise, where the block layer * takes care of reading zeros beyond EOF if backing file is short */ bool supports_backing; bool has_variable_length; /* * Drivers setting this field must be able to work with just a plain * filename with ':' as a prefix, and no other options. * Options may be extracted from the filename by implementing * bdrv_parse_filename. */ const char *protocol_name; /* List of options for creating images, terminated by name == NULL */ QemuOptsList *create_opts; /* List of options for image amend */ QemuOptsList *amend_opts; /* * If this driver supports reopening images this contains a * NULL-terminated list of the runtime options that can be * modified. If an option in this list is unspecified during * reopen then it _must_ be reset to its default value or return * an error. */ const char *const *mutable_opts; /* * Pointer to a NULL-terminated array of names of strong options * that can be specified for bdrv_open(). A strong option is one * that changes the data of a BDS. * If this pointer is NULL, the array is considered empty. * "filename" and "driver" are always considered strong. */ const char *const *strong_runtime_opts; /* * Global state (GS) API. These functions run under the BQL. * * See include/block/block-global-state.h for more information about * the GS API. */ /* * This function is invoked under BQL before .bdrv_co_amend() * (which in contrast does not necessarily run under the BQL) * to allow driver-specific initialization code that requires * the BQL, like setting up specific permission flags. */ int (*bdrv_amend_pre_run)(BlockDriverState *bs, Error **errp); /* * This function is invoked under BQL after .bdrv_co_amend() * to allow cleaning up what was done in .bdrv_amend_pre_run(). */ void (*bdrv_amend_clean)(BlockDriverState *bs); /* * Return true if @to_replace can be replaced by a BDS with the * same data as @bs without it affecting @bs's behavior (that is, * without it being visible to @bs's parents). */ bool (*bdrv_recurse_can_replace)(BlockDriverState *bs, BlockDriverState *to_replace); int (*bdrv_probe_device)(const char *filename); /* * Any driver implementing this callback is expected to be able to handle * NULL file names in its .bdrv_open() implementation. */ void (*bdrv_parse_filename)(const char *filename, QDict *options, Error **errp); /* For handling image reopen for split or non-split files. */ int (*bdrv_reopen_prepare)(BDRVReopenState *reopen_state, BlockReopenQueue *queue, Error **errp); void (*bdrv_reopen_commit)(BDRVReopenState *reopen_state); void (*bdrv_reopen_commit_post)(BDRVReopenState *reopen_state); void (*bdrv_reopen_abort)(BDRVReopenState *reopen_state); void (*bdrv_join_options)(QDict *options, QDict *old_options); int (*bdrv_open)(BlockDriverState *bs, QDict *options, int flags, Error **errp); /* Protocol drivers should implement this instead of bdrv_open */ int (*bdrv_file_open)(BlockDriverState *bs, QDict *options, int flags, Error **errp); void (*bdrv_close)(BlockDriverState *bs); int coroutine_fn (*bdrv_co_create)(BlockdevCreateOptions *opts, Error **errp); int coroutine_fn (*bdrv_co_create_opts)(BlockDriver *drv, const char *filename, QemuOpts *opts, Error **errp); int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts, BlockDriverAmendStatusCB *status_cb, void *cb_opaque, bool force, Error **errp); int (*bdrv_make_empty)(BlockDriverState *bs); /* * Refreshes the bs->exact_filename field. If that is impossible, * bs->exact_filename has to be left empty. */ void (*bdrv_refresh_filename)(BlockDriverState *bs); /* * Gathers the open options for all children into @target. * A simple format driver (without backing file support) might * implement this function like this: * * QINCREF(bs->file->bs->full_open_options); * qdict_put(target, "file", bs->file->bs->full_open_options); * * If not specified, the generic implementation will simply put * all children's options under their respective name. * * @backing_overridden is true when bs->backing seems not to be * the child that would result from opening bs->backing_file. * Therefore, if it is true, the backing child's options should be * gathered; otherwise, there is no need since the backing child * is the one implied by the image header. * * Note that ideally this function would not be needed. Every * block driver which implements it is probably doing something * shady regarding its runtime option structure. */ void (*bdrv_gather_child_options)(BlockDriverState *bs, QDict *target, bool backing_overridden); /* * Returns an allocated string which is the directory name of this BDS: It * will be used to make relative filenames absolute by prepending this * function's return value to them. */ char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp); /* * This informs the driver that we are no longer interested in the result * of in-flight requests, so don't waste the time if possible. * * One example usage is to avoid waiting for an nbd target node reconnect * timeout during job-cancel with force=true. */ void (*bdrv_cancel_in_flight)(BlockDriverState *bs); int (*bdrv_inactivate)(BlockDriverState *bs); int (*bdrv_snapshot_create)(BlockDriverState *bs, QEMUSnapshotInfo *sn_info); int (*bdrv_snapshot_goto)(BlockDriverState *bs, const char *snapshot_id); int (*bdrv_snapshot_delete)(BlockDriverState *bs, const char *snapshot_id, const char *name, Error **errp); int (*bdrv_snapshot_list)(BlockDriverState *bs, QEMUSnapshotInfo **psn_info); int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs, const char *snapshot_id, const char *name, Error **errp); int (*bdrv_change_backing_file)(BlockDriverState *bs, const char *backing_file, const char *backing_fmt); /* TODO Better pass a option string/QDict/QemuOpts to add any rule? */ int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event, const char *tag); int (*bdrv_debug_remove_breakpoint)(BlockDriverState *bs, const char *tag); int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag); bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag); void (*bdrv_refresh_limits)(BlockDriverState *bs, Error **errp); /* * Returns 1 if newly created images are guaranteed to contain only * zeros, 0 otherwise. */ int (*bdrv_has_zero_init)(BlockDriverState *bs); /* * Remove fd handlers, timers, and other event loop callbacks so the event * loop is no longer in use. Called with no in-flight requests and in * depth-first traversal order with parents before child nodes. */ void (*bdrv_detach_aio_context)(BlockDriverState *bs); /* * Add fd handlers, timers, and other event loop callbacks so I/O requests * can be processed again. Called with no in-flight requests and in * depth-first traversal order with child nodes before parent nodes. */ void (*bdrv_attach_aio_context)(BlockDriverState *bs, AioContext *new_context); /** * Try to get @bs's logical and physical block size. * On success, store them in @bsz and return zero. * On failure, return negative errno. */ int (*bdrv_probe_blocksizes)(BlockDriverState *bs, BlockSizes *bsz); /** * Try to get @bs's geometry (cyls, heads, sectors) * On success, store them in @geo and return 0. * On failure return -errno. * Only drivers that want to override guest geometry implement this * callback; see hd_geometry_guess(). */ int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo); void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, Error **errp); void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child, Error **errp); /** * Informs the block driver that a permission change is intended. The * driver checks whether the change is permissible and may take other * preparations for the change (e.g. get file system locks). This operation * is always followed either by a call to either .bdrv_set_perm or * .bdrv_abort_perm_update. * * Checks whether the requested set of cumulative permissions in @perm * can be granted for accessing @bs and whether no other users are using * permissions other than those given in @shared (both arguments take * BLK_PERM_* bitmasks). * * If both conditions are met, 0 is returned. Otherwise, -errno is returned * and errp is set to an error describing the conflict. */ int (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm, uint64_t shared, Error **errp); /** * Called to inform the driver that the set of cumulative set of used * permissions for @bs has changed to @perm, and the set of sharable * permission to @shared. The driver can use this to propagate changes to * its children (i.e. request permissions only if a parent actually needs * them). * * This function is only invoked after bdrv_check_perm(), so block drivers * may rely on preparations made in their .bdrv_check_perm implementation. */ void (*bdrv_set_perm)(BlockDriverState *bs, uint64_t perm, uint64_t shared); /* * Called to inform the driver that after a previous bdrv_check_perm() * call, the permission update is not performed and any preparations made * for it (e.g. taken file locks) need to be undone. * * This function can be called even for nodes that never saw a * bdrv_check_perm() call. It is a no-op then. */ void (*bdrv_abort_perm_update)(BlockDriverState *bs); /** * Returns in @nperm and @nshared the permissions that the driver for @bs * needs on its child @c, based on the cumulative permissions requested by * the parents in @parent_perm and @parent_shared. * * If @c is NULL, return the permissions for attaching a new child for the * given @child_class and @role. * * If @reopen_queue is non-NULL, don't return the currently needed * permissions, but those that will be needed after applying the * @reopen_queue. */ void (*bdrv_child_perm)(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, uint64_t parent_perm, uint64_t parent_shared, uint64_t *nperm, uint64_t *nshared); /** * Register/unregister a buffer for I/O. For example, when the driver is * interested to know the memory areas that will later be used in iovs, so * that it can do IOMMU mapping with VFIO etc., in order to get better * performance. In the case of VFIO drivers, this callback is used to do * DMA mapping for hot buffers. * * Returns: true on success, false on failure */ bool (*bdrv_register_buf)(BlockDriverState *bs, void *host, size_t size, Error **errp); void (*bdrv_unregister_buf)(BlockDriverState *bs, void *host, size_t size); /* * This field is modified only under the BQL, and is part of * the global state. */ QLIST_ENTRY(BlockDriver) list; /* * I/O API functions. These functions are thread-safe. * * See include/block/block-io.h for more information about * the I/O API. */ int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename); int coroutine_fn (*bdrv_co_amend)(BlockDriverState *bs, BlockdevAmendOptions *opts, bool force, Error **errp); /* aio */ BlockAIOCB *(*bdrv_aio_preadv)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); BlockAIOCB *(*bdrv_aio_pwritev)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); BlockAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque); BlockAIOCB *(*bdrv_aio_pdiscard)(BlockDriverState *bs, int64_t offset, int bytes, BlockCompletionFunc *cb, void *opaque); int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); /** * @offset: position in bytes to read at * @bytes: number of bytes to read * @qiov: the buffers to fill with read data * @flags: currently unused, always 0 * * @offset and @bytes will be a multiple of 'request_alignment', * but the length of individual @qiov elements does not have to * be a multiple. * * @bytes will always equal the total size of @qiov, and will be * no larger than 'max_transfer'. * * The buffer in @qiov may point directly to guest memory. */ int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags); int coroutine_fn (*bdrv_co_preadv_part)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags); int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags); /** * @offset: position in bytes to write at * @bytes: number of bytes to write * @qiov: the buffers containing data to write * @flags: zero or more bits allowed by 'supported_write_flags' * * @offset and @bytes will be a multiple of 'request_alignment', * but the length of individual @qiov elements does not have to * be a multiple. * * @bytes will always equal the total size of @qiov, and will be * no larger than 'max_transfer'. * * The buffer in @qiov may point directly to guest memory. */ int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags); int coroutine_fn (*bdrv_co_pwritev_part)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags); /* * Efficiently zero a region of the disk image. Typically an image format * would use a compact metadata representation to implement this. This * function pointer may be NULL or return -ENOSUP and .bdrv_co_writev() * will be called instead. */ int coroutine_fn (*bdrv_co_pwrite_zeroes)(BlockDriverState *bs, int64_t offset, int64_t bytes, BdrvRequestFlags flags); int coroutine_fn (*bdrv_co_pdiscard)(BlockDriverState *bs, int64_t offset, int64_t bytes); /* * Map [offset, offset + nbytes) range onto a child of @bs to copy from, * and invoke bdrv_co_copy_range_from(child, ...), or invoke * bdrv_co_copy_range_to() if @bs is the leaf child to copy data from. * * See the comment of bdrv_co_copy_range for the parameter and return value * semantics. */ int coroutine_fn (*bdrv_co_copy_range_from)(BlockDriverState *bs, BdrvChild *src, int64_t offset, BdrvChild *dst, int64_t dst_offset, int64_t bytes, BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); /* * Map [offset, offset + nbytes) range onto a child of bs to copy data to, * and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy * operation if @bs is the leaf and @src has the same BlockDriver. Return * -ENOTSUP if @bs is the leaf but @src has a different BlockDriver. * * See the comment of bdrv_co_copy_range for the parameter and return value * semantics. */ int coroutine_fn (*bdrv_co_copy_range_to)(BlockDriverState *bs, BdrvChild *src, int64_t src_offset, BdrvChild *dst, int64_t dst_offset, int64_t bytes, BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); /* * Building block for bdrv_block_status[_above] and * bdrv_is_allocated[_above]. The driver should answer only * according to the current layer, and should only need to set * BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID, * and/or BDRV_BLOCK_RAW; if the current layer defers to a backing * layer, the result should be 0 (and not BDRV_BLOCK_ZERO). See * block.h for the overall meaning of the bits. As a hint, the * flag want_zero is true if the caller cares more about precise * mappings (favor accurate _OFFSET_VALID/_ZERO) or false for * overall allocation (favor larger *pnum, perhaps by reporting * _DATA instead of _ZERO). The block layer guarantees input * clamped to bdrv_getlength() and aligned to request_alignment, * as well as non-NULL pnum, map, and file; in turn, the driver * must return an error or set pnum to an aligned non-zero value. * * Note that @bytes is just a hint on how big of a region the * caller wants to inspect. It is not a limit on *pnum. * Implementations are free to return larger values of *pnum if * doing so does not incur a performance penalty. * * block/io.c's bdrv_co_block_status() will utilize an unclamped * *pnum value for the block-status cache on protocol nodes, prior * to clamping *pnum for return to its caller. */ int coroutine_fn (*bdrv_co_block_status)(BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, int64_t *map, BlockDriverState **file); /* * Snapshot-access API. * * Block-driver may provide snapshot-access API: special functions to access * some internal "snapshot". The functions are similar with normal * read/block_status/discard handler, but don't have any specific handling * in generic block-layer: no serializing, no alignment, no tracked * requests. So, block-driver that realizes these APIs is fully responsible * for synchronization between snapshot-access API and normal IO requests. * * TODO: To be able to support qcow2's internal snapshots, this API will * need to be extended to: * - be able to select a specific snapshot * - receive the snapshot's actual length (which may differ from bs's * length) */ int coroutine_fn (*bdrv_co_preadv_snapshot)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset); int coroutine_fn (*bdrv_co_snapshot_block_status)(BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, int64_t *map, BlockDriverState **file); int coroutine_fn (*bdrv_co_pdiscard_snapshot)(BlockDriverState *bs, int64_t offset, int64_t bytes); /* * Invalidate any cached meta-data. */ void coroutine_fn (*bdrv_co_invalidate_cache)(BlockDriverState *bs, Error **errp); /* * Flushes all data for all layers by calling bdrv_co_flush for underlying * layers, if needed. This function is needed for deterministic * synchronization of the flush finishing callback. */ int coroutine_fn (*bdrv_co_flush)(BlockDriverState *bs); /* Delete a created file. */ int coroutine_fn (*bdrv_co_delete_file)(BlockDriverState *bs, Error **errp); /* * Flushes all data that was already written to the OS all the way down to * the disk (for example file-posix.c calls fsync()). */ int coroutine_fn (*bdrv_co_flush_to_disk)(BlockDriverState *bs); /* * Flushes all internal caches to the OS. The data may still sit in a * writeback cache of the host OS, but it will survive a crash of the qemu * process. */ int coroutine_fn (*bdrv_co_flush_to_os)(BlockDriverState *bs); /* * Truncate @bs to @offset bytes using the given @prealloc mode * when growing. Modes other than PREALLOC_MODE_OFF should be * rejected when shrinking @bs. * * If @exact is true, @bs must be resized to exactly @offset. * Otherwise, it is sufficient for @bs (if it is a host block * device and thus there is no way to resize it) to be at least * @offset bytes in length. * * If @exact is true and this function fails but would succeed * with @exact = false, it should return -ENOTSUP. */ int coroutine_fn (*bdrv_co_truncate)(BlockDriverState *bs, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); int64_t (*bdrv_getlength)(BlockDriverState *bs); int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs); BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs, Error **errp); int coroutine_fn (*bdrv_co_pwritev_compressed)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov); int coroutine_fn (*bdrv_co_pwritev_compressed_part)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset); int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi); ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs, Error **errp); BlockStatsSpecific *(*bdrv_get_specific_stats)(BlockDriverState *bs); int coroutine_fn (*bdrv_save_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); int coroutine_fn (*bdrv_load_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); /* removable device specific */ bool (*bdrv_is_inserted)(BlockDriverState *bs); void (*bdrv_eject)(BlockDriverState *bs, bool eject_flag); void (*bdrv_lock_medium)(BlockDriverState *bs, bool locked); /* to control generic scsi devices */ BlockAIOCB *(*bdrv_aio_ioctl)(BlockDriverState *bs, unsigned long int req, void *buf, BlockCompletionFunc *cb, void *opaque); int coroutine_fn (*bdrv_co_ioctl)(BlockDriverState *bs, unsigned long int req, void *buf); /* * Returns 0 for completed check, -errno for internal errors. * The check results are stored in result. */ int coroutine_fn (*bdrv_co_check)(BlockDriverState *bs, BdrvCheckResult *result, BdrvCheckMode fix); void (*bdrv_debug_event)(BlockDriverState *bs, BlkdebugEvent event); /* io queue for linux-aio */ void (*bdrv_io_plug)(BlockDriverState *bs); void (*bdrv_io_unplug)(BlockDriverState *bs); /** * bdrv_co_drain_begin is called if implemented in the beginning of a * drain operation to drain and stop any internal sources of requests in * the driver. * bdrv_co_drain_end is called if implemented at the end of the drain. * * They should be used by the driver to e.g. manage scheduled I/O * requests, or toggle an internal state. After the end of the drain new * requests will continue normally. */ void coroutine_fn (*bdrv_co_drain_begin)(BlockDriverState *bs); void coroutine_fn (*bdrv_co_drain_end)(BlockDriverState *bs); bool (*bdrv_supports_persistent_dirty_bitmap)(BlockDriverState *bs); bool coroutine_fn (*bdrv_co_can_store_new_dirty_bitmap)( BlockDriverState *bs, const char *name, uint32_t granularity, Error **errp); int coroutine_fn (*bdrv_co_remove_persistent_dirty_bitmap)( BlockDriverState *bs, const char *name, Error **errp); }; static inline bool block_driver_can_compress(BlockDriver *drv) { return drv->bdrv_co_pwritev_compressed || drv->bdrv_co_pwritev_compressed_part; } typedef struct BlockLimits { /* * Alignment requirement, in bytes, for offset/length of I/O * requests. Must be a power of 2 less than INT_MAX; defaults to * 1 for drivers with modern byte interfaces, and to 512 * otherwise. */ uint32_t request_alignment; /* * Maximum number of bytes that can be discarded at once. Must be multiple * of pdiscard_alignment, but need not be power of 2. May be 0 if no * inherent 64-bit limit. */ int64_t max_pdiscard; /* * Optimal alignment for discard requests in bytes. A power of 2 * is best but not mandatory. Must be a multiple of * bl.request_alignment, and must be less than max_pdiscard if * that is set. May be 0 if bl.request_alignment is good enough */ uint32_t pdiscard_alignment; /* * Maximum number of bytes that can zeroized at once. Must be multiple of * pwrite_zeroes_alignment. 0 means no limit. */ int64_t max_pwrite_zeroes; /* * Optimal alignment for write zeroes requests in bytes. A power * of 2 is best but not mandatory. Must be a multiple of * bl.request_alignment, and must be less than max_pwrite_zeroes * if that is set. May be 0 if bl.request_alignment is good * enough */ uint32_t pwrite_zeroes_alignment; /* * Optimal transfer length in bytes. A power of 2 is best but not * mandatory. Must be a multiple of bl.request_alignment, or 0 if * no preferred size */ uint32_t opt_transfer; /* * Maximal transfer length in bytes. Need not be power of 2, but * must be multiple of opt_transfer and bl.request_alignment, or 0 * for no 32-bit limit. For now, anything larger than INT_MAX is * clamped down. */ uint32_t max_transfer; /* * Maximal hardware transfer length in bytes. Applies whenever * transfers to the device bypass the kernel I/O scheduler, for * example with SG_IO. If larger than max_transfer or if zero, * blk_get_max_hw_transfer will fall back to max_transfer. */ uint64_t max_hw_transfer; /* * Maximal number of scatter/gather elements allowed by the hardware. * Applies whenever transfers to the device bypass the kernel I/O * scheduler, for example with SG_IO. If larger than max_iov * or if zero, blk_get_max_hw_iov will fall back to max_iov. */ int max_hw_iov; /* memory alignment, in bytes so that no bounce buffer is needed */ size_t min_mem_alignment; /* memory alignment, in bytes, for bounce buffer */ size_t opt_mem_alignment; /* maximum number of iovec elements */ int max_iov; } BlockLimits; typedef struct BdrvOpBlocker BdrvOpBlocker; typedef struct BdrvAioNotifier { void (*attached_aio_context)(AioContext *new_context, void *opaque); void (*detach_aio_context)(void *opaque); void *opaque; bool deleted; QLIST_ENTRY(BdrvAioNotifier) list; } BdrvAioNotifier; struct BdrvChildClass { /* * If true, bdrv_replace_node() doesn't change the node this BdrvChild * points to. */ bool stay_at_node; /* * If true, the parent is a BlockDriverState and bdrv_next_all_states() * will return it. This information is used for drain_all, where every node * will be drained separately, so the drain only needs to be propagated to * non-BDS parents. */ bool parent_is_bds; /* * Global state (GS) API. These functions run under the BQL. * * See include/block/block-global-state.h for more information about * the GS API. */ void (*inherit_options)(BdrvChildRole role, bool parent_is_format, int *child_flags, QDict *child_options, int parent_flags, QDict *parent_options); void (*change_media)(BdrvChild *child, bool load); /* * Returns a malloced string that describes the parent of the child for a * human reader. This could be a node-name, BlockBackend name, qdev ID or * QOM path of the device owning the BlockBackend, job type and ID etc. The * caller is responsible for freeing the memory. */ char *(*get_parent_desc)(BdrvChild *child); /* * Notifies the parent that the child has been activated/inactivated (e.g. * when migration is completing) and it can start/stop requesting * permissions and doing I/O on it. */ void (*activate)(BdrvChild *child, Error **errp); int (*inactivate)(BdrvChild *child); void (*attach)(BdrvChild *child); void (*detach)(BdrvChild *child); /* * Notifies the parent that the filename of its child has changed (e.g. * because the direct child was removed from the backing chain), so that it * can update its reference. */ int (*update_filename)(BdrvChild *child, BlockDriverState *new_base, const char *filename, Error **errp); bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx, GHashTable *visited, Transaction *tran, Error **errp); /* * I/O API functions. These functions are thread-safe. * * See include/block/block-io.h for more information about * the I/O API. */ void (*resize)(BdrvChild *child); /* * Returns a name that is supposedly more useful for human users than the * node name for identifying the node in question (in particular, a BB * name), or NULL if the parent can't provide a better name. */ const char *(*get_name)(BdrvChild *child); AioContext *(*get_parent_aio_context)(BdrvChild *child); /* * If this pair of functions is implemented, the parent doesn't issue new * requests after returning from .drained_begin() until .drained_end() is * called. * * These functions must not change the graph (and therefore also must not * call aio_poll(), which could change the graph indirectly). * * If drained_end() schedules background operations, it must atomically * increment *drained_end_counter for each such operation and atomically * decrement it once the operation has settled. * * Note that this can be nested. If drained_begin() was called twice, new * I/O is allowed only after drained_end() was called twice, too. */ void (*drained_begin)(BdrvChild *child); void (*drained_end)(BdrvChild *child, int *drained_end_counter); /* * Returns whether the parent has pending requests for the child. This * callback is polled after .drained_begin() has been called until all * activity on the child has stopped. */ bool (*drained_poll)(BdrvChild *child); }; extern const BdrvChildClass child_of_bds; struct BdrvChild { BlockDriverState *bs; char *name; const BdrvChildClass *klass; BdrvChildRole role; void *opaque; /** * Granted permissions for operating on this BdrvChild (BLK_PERM_* bitmask) */ uint64_t perm; /** * Permissions that can still be granted to other users of @bs while this * BdrvChild is still attached to it. (BLK_PERM_* bitmask) */ uint64_t shared_perm; /* * This link is frozen: the child can neither be replaced nor * detached from the parent. */ bool frozen; /* * How many times the parent of this child has been drained * (through klass->drained_*). * Usually, this is equal to bs->quiesce_counter (potentially * reduced by bdrv_drain_all_count). It may differ while the * child is entering or leaving a drained section. */ int parent_quiesce_counter; QLIST_ENTRY(BdrvChild) next; QLIST_ENTRY(BdrvChild) next_parent; }; /* * Allows bdrv_co_block_status() to cache one data region for a * protocol node. * * @valid: Whether the cache is valid (should be accessed with atomic * functions so this can be reset by RCU readers) * @data_start: Offset where we know (or strongly assume) is data * @data_end: Offset where the data region ends (which is not necessarily * the start of a zeroed region) */ typedef struct BdrvBlockStatusCache { struct rcu_head rcu; bool valid; int64_t data_start; int64_t data_end; } BdrvBlockStatusCache; struct BlockDriverState { /* * Protected by big QEMU lock or read-only after opening. No special * locking needed during I/O... */ int open_flags; /* flags used to open the file, re-used for re-open */ bool encrypted; /* if true, the media is encrypted */ bool sg; /* if true, the device is a /dev/sg* */ bool probed; /* if true, format was probed rather than specified */ bool force_share; /* if true, always allow all shared permissions */ bool implicit; /* if true, this filter node was automatically inserted */ BlockDriver *drv; /* NULL means no media */ void *opaque; AioContext *aio_context; /* event loop used for fd handlers, timers, etc */ /* * long-running tasks intended to always use the same AioContext as this * BDS may register themselves in this list to be notified of changes * regarding this BDS's context */ QLIST_HEAD(, BdrvAioNotifier) aio_notifiers; bool walking_aio_notifiers; /* to make removal during iteration safe */ char filename[PATH_MAX]; /* * If not empty, this image is a diff in relation to backing_file. * Note that this is the name given in the image header and * therefore may or may not be equal to .backing->bs->filename. * If this field contains a relative path, it is to be resolved * relatively to the overlay's location. */ char backing_file[PATH_MAX]; /* * The backing filename indicated by the image header. Contrary * to backing_file, if we ever open this file, auto_backing_file * is replaced by the resulting BDS's filename (i.e. after a * bdrv_refresh_filename() run). */ char auto_backing_file[PATH_MAX]; char backing_format[16]; /* if non-zero and backing_file exists */ QDict *full_open_options; char exact_filename[PATH_MAX]; /* I/O Limits */ BlockLimits bl; /* * Flags honored during pread */ BdrvRequestFlags supported_read_flags; /* * Flags honored during pwrite (so far: BDRV_REQ_FUA, * BDRV_REQ_WRITE_UNCHANGED). * If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those * writes will be issued as normal writes without the flag set. * This is important to note for drivers that do not explicitly * request a WRITE permission for their children and instead take * the same permissions as their parent did (this is commonly what * block filters do). Such drivers have to be aware that the * parent may have taken a WRITE_UNCHANGED permission only and is * issuing such requests. Drivers either must make sure that * these requests do not result in plain WRITE accesses (usually * by supporting BDRV_REQ_WRITE_UNCHANGED, and then forwarding * every incoming write request as-is, including potentially that * flag), or they have to explicitly take the WRITE permission for * their children. */ BdrvRequestFlags supported_write_flags; /* * Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA, * BDRV_REQ_MAY_UNMAP, BDRV_REQ_WRITE_UNCHANGED) */ BdrvRequestFlags supported_zero_flags; /* * Flags honoured during truncate (so far: BDRV_REQ_ZERO_WRITE). * * If BDRV_REQ_ZERO_WRITE is given, the truncate operation must make sure * that any added space reads as all zeros. If this can't be guaranteed, * the operation must fail. */ BdrvRequestFlags supported_truncate_flags; /* the following member gives a name to every node on the bs graph. */ char node_name[32]; /* element of the list of named nodes building the graph */ QTAILQ_ENTRY(BlockDriverState) node_list; /* element of the list of all BlockDriverStates (all_bdrv_states) */ QTAILQ_ENTRY(BlockDriverState) bs_list; /* element of the list of monitor-owned BDS */ QTAILQ_ENTRY(BlockDriverState) monitor_list; int refcnt; /* operation blockers. Protected by BQL. */ QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX]; /* * The node that this node inherited default options from (and a reopen on * which can affect this node by changing these defaults). This is always a * parent node of this node. */ BlockDriverState *inherits_from; /* * @backing and @file are some of @children or NULL. All these three fields * (@file, @backing and @children) are modified only in * bdrv_child_cb_attach() and bdrv_child_cb_detach(). * * See also comment in include/block/block.h, to learn how backing and file * are connected with BdrvChildRole. */ QLIST_HEAD(, BdrvChild) children; BdrvChild *backing; BdrvChild *file; QLIST_HEAD(, BdrvChild) parents; QDict *options; QDict *explicit_options; BlockdevDetectZeroesOptions detect_zeroes; /* The error object in use for blocking operations on backing_hd */ Error *backing_blocker; /* Protected by AioContext lock */ /* * If we are reading a disk image, give its size in sectors. * Generally read-only; it is written to by load_snapshot and * save_snaphost, but the block layer is quiescent during those. */ int64_t total_sectors; /* threshold limit for writes, in bytes. "High water mark". */ uint64_t write_threshold_offset; /* * Writing to the list requires the BQL _and_ the dirty_bitmap_mutex. * Reading from the list can be done with either the BQL or the * dirty_bitmap_mutex. Modifying a bitmap only requires * dirty_bitmap_mutex. */ QemuMutex dirty_bitmap_mutex; QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps; /* Offset after the highest byte written to */ Stat64 wr_highest_offset; /* * If true, copy read backing sectors into image. Can be >1 if more * than one client has requested copy-on-read. Accessed with atomic * ops. */ int copy_on_read; /* * number of in-flight requests; overall and serialising. * Accessed with atomic ops. */ unsigned int in_flight; unsigned int serialising_in_flight; /* * counter for nested bdrv_io_plug. * Accessed with atomic ops. */ unsigned io_plugged; /* do we need to tell the quest if we have a volatile write cache? */ int enable_write_cache; /* Accessed with atomic ops. */ int quiesce_counter; int recursive_quiesce_counter; unsigned int write_gen; /* Current data generation */ /* Protected by reqs_lock. */ CoMutex reqs_lock; QLIST_HEAD(, BdrvTrackedRequest) tracked_requests; CoQueue flush_queue; /* Serializing flush queue */ bool active_flush_req; /* Flush request in flight? */ /* Only read/written by whoever has set active_flush_req to true. */ unsigned int flushed_gen; /* Flushed write generation */ /* BdrvChild links to this node may never be frozen */ bool never_freeze; /* Lock for block-status cache RCU writers */ CoMutex bsc_modify_lock; /* Always non-NULL, but must only be dereferenced under an RCU read guard */ BdrvBlockStatusCache *block_status_cache; }; struct BlockBackendRootState { int open_flags; BlockdevDetectZeroesOptions detect_zeroes; }; typedef enum BlockMirrorBackingMode { /* * Reuse the existing backing chain from the source for the target. * - sync=full: Set backing BDS to NULL. * - sync=top: Use source's backing BDS. * - sync=none: Use source as the backing BDS. */ MIRROR_SOURCE_BACKING_CHAIN, /* Open the target's backing chain completely anew */ MIRROR_OPEN_BACKING_CHAIN, /* Do not change the target's backing BDS after job completion */ MIRROR_LEAVE_BACKING_CHAIN, } BlockMirrorBackingMode; /* * Essential block drivers which must always be statically linked into qemu, and * which therefore can be accessed without using bdrv_find_format() */ extern BlockDriver bdrv_file; extern BlockDriver bdrv_raw; extern BlockDriver bdrv_qcow2; extern unsigned int bdrv_drain_all_count; extern QemuOptsList bdrv_create_opts_simple; /* * Common functions that are neither I/O nor Global State. * * See include/block/block-commmon.h for more information about * the Common API. */ static inline BlockDriverState *child_bs(BdrvChild *child) { return child ? child->bs : NULL; } int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp); char *create_tmp_file(Error **errp); void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, QDict *options); int bdrv_check_qiov_request(int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset, Error **errp); #ifdef _WIN32 int is_windows_drive(const char *filename); #endif #endif /* BLOCK_INT_COMMON_H */