86b1cf3227
Currently, blk_is_read_only() tells whether a given BlockBackend can only be used in read-only mode because its root node is read-only. Some callers actually try to answer a slightly different question: Is the BlockBackend configured to be writable, by taking write permissions on the root node? This can differ, for example, for CD-ROM devices which don't take write permissions, but may be backed by a writable image file. scsi-cd allows write requests to the drive if blk_is_read_only() returns false. However, the write request will immediately run into an assertion failure because the write permission is missing. This patch introduces separate functions for both questions. blk_supports_write_perm() answers the question whether the block node/image file can support writable devices, whereas blk_is_writable() tells whether the BlockBackend is currently configured to be writable. All calls of blk_is_read_only() are converted to one of the two new functions. Fixes: https://bugs.launchpad.net/bugs/1906693 Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20210118123448.307825-2-kwolf@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
273 lines
13 KiB
C
273 lines
13 KiB
C
/*
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* QEMU Block backends
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*
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* Copyright (C) 2014-2016 Red Hat, Inc.
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*
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* Authors:
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* Markus Armbruster <armbru@redhat.com>,
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1
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* or later. See the COPYING.LIB file in the top-level directory.
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*/
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#ifndef BLOCK_BACKEND_H
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#define BLOCK_BACKEND_H
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#include "qemu/iov.h"
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#include "block/throttle-groups.h"
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/*
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* TODO Have to include block/block.h for a bunch of block layer
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* types. Unfortunately, this pulls in the whole BlockDriverState
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* API, which we don't want used by many BlockBackend users. Some of
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* the types belong here, and the rest should be split into a common
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* header and one for the BlockDriverState API.
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*/
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#include "block/block.h"
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/* Callbacks for block device models */
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typedef struct BlockDevOps {
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/*
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* Runs when virtual media changed (monitor commands eject, change)
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* Argument load is true on load and false on eject.
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* Beware: doesn't run when a host device's physical media
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* changes. Sure would be useful if it did.
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* Device models with removable media must implement this callback.
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*/
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void (*change_media_cb)(void *opaque, bool load, Error **errp);
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/*
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* Runs when an eject request is issued from the monitor, the tray
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* is closed, and the medium is locked.
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* Device models that do not implement is_medium_locked will not need
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* this callback. Device models that can lock the medium or tray might
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* want to implement the callback and unlock the tray when "force" is
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* true, even if they do not support eject requests.
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*/
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void (*eject_request_cb)(void *opaque, bool force);
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/*
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* Is the virtual tray open?
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* Device models implement this only when the device has a tray.
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*/
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bool (*is_tray_open)(void *opaque);
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/*
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* Is the virtual medium locked into the device?
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* Device models implement this only when device has such a lock.
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*/
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bool (*is_medium_locked)(void *opaque);
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/*
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* Runs when the size changed (e.g. monitor command block_resize)
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*/
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void (*resize_cb)(void *opaque);
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/*
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* Runs when the backend receives a drain request.
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*/
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void (*drained_begin)(void *opaque);
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/*
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* Runs when the backend's last drain request ends.
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*/
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void (*drained_end)(void *opaque);
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} BlockDevOps;
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/* This struct is embedded in (the private) BlockBackend struct and contains
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* fields that must be public. This is in particular for QLIST_ENTRY() and
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* friends so that BlockBackends can be kept in lists outside block-backend.c
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* */
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typedef struct BlockBackendPublic {
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ThrottleGroupMember throttle_group_member;
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} BlockBackendPublic;
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BlockBackend *blk_new(AioContext *ctx, uint64_t perm, uint64_t shared_perm);
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BlockBackend *blk_new_with_bs(BlockDriverState *bs, uint64_t perm,
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uint64_t shared_perm, Error **errp);
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BlockBackend *blk_new_open(const char *filename, const char *reference,
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QDict *options, int flags, Error **errp);
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int blk_get_refcnt(BlockBackend *blk);
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void blk_ref(BlockBackend *blk);
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void blk_unref(BlockBackend *blk);
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void blk_remove_all_bs(void);
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const char *blk_name(const BlockBackend *blk);
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BlockBackend *blk_by_name(const char *name);
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BlockBackend *blk_next(BlockBackend *blk);
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BlockBackend *blk_all_next(BlockBackend *blk);
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bool monitor_add_blk(BlockBackend *blk, const char *name, Error **errp);
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void monitor_remove_blk(BlockBackend *blk);
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BlockBackendPublic *blk_get_public(BlockBackend *blk);
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BlockBackend *blk_by_public(BlockBackendPublic *public);
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BlockDriverState *blk_bs(BlockBackend *blk);
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void blk_remove_bs(BlockBackend *blk);
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int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp);
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bool bdrv_has_blk(BlockDriverState *bs);
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bool bdrv_is_root_node(BlockDriverState *bs);
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int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
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Error **errp);
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void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm);
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void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
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void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow);
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void blk_set_disable_request_queuing(BlockBackend *blk, bool disable);
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void blk_iostatus_enable(BlockBackend *blk);
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bool blk_iostatus_is_enabled(const BlockBackend *blk);
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BlockDeviceIoStatus blk_iostatus(const BlockBackend *blk);
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void blk_iostatus_disable(BlockBackend *blk);
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void blk_iostatus_reset(BlockBackend *blk);
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void blk_iostatus_set_err(BlockBackend *blk, int error);
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int blk_attach_dev(BlockBackend *blk, DeviceState *dev);
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void blk_detach_dev(BlockBackend *blk, DeviceState *dev);
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DeviceState *blk_get_attached_dev(BlockBackend *blk);
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char *blk_get_attached_dev_id(BlockBackend *blk);
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BlockBackend *blk_by_dev(void *dev);
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BlockBackend *blk_by_qdev_id(const char *id, Error **errp);
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void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque);
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int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
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unsigned int bytes, QEMUIOVector *qiov,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_pwritev_part(BlockBackend *blk, int64_t offset,
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unsigned int bytes,
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QEMUIOVector *qiov, size_t qiov_offset,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
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unsigned int bytes, QEMUIOVector *qiov,
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BdrvRequestFlags flags);
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static inline int coroutine_fn blk_co_pread(BlockBackend *blk, int64_t offset,
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unsigned int bytes, void *buf,
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BdrvRequestFlags flags)
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{
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QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
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return blk_co_preadv(blk, offset, bytes, &qiov, flags);
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}
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static inline int coroutine_fn blk_co_pwrite(BlockBackend *blk, int64_t offset,
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unsigned int bytes, void *buf,
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BdrvRequestFlags flags)
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{
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QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
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return blk_co_pwritev(blk, offset, bytes, &qiov, flags);
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}
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int blk_pwrite_zeroes(BlockBackend *blk, int64_t offset,
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int bytes, BdrvRequestFlags flags);
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BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
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int bytes, BdrvRequestFlags flags,
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BlockCompletionFunc *cb, void *opaque);
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int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags);
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int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int bytes);
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int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int bytes,
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BdrvRequestFlags flags);
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int64_t blk_getlength(BlockBackend *blk);
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void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr);
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int64_t blk_nb_sectors(BlockBackend *blk);
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BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
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QEMUIOVector *qiov, BdrvRequestFlags flags,
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BlockCompletionFunc *cb, void *opaque);
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BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
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QEMUIOVector *qiov, BdrvRequestFlags flags,
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BlockCompletionFunc *cb, void *opaque);
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BlockAIOCB *blk_aio_flush(BlockBackend *blk,
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BlockCompletionFunc *cb, void *opaque);
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BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk, int64_t offset, int bytes,
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BlockCompletionFunc *cb, void *opaque);
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void blk_aio_cancel(BlockAIOCB *acb);
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void blk_aio_cancel_async(BlockAIOCB *acb);
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int blk_ioctl(BlockBackend *blk, unsigned long int req, void *buf);
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BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
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BlockCompletionFunc *cb, void *opaque);
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int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int bytes);
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int blk_co_flush(BlockBackend *blk);
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int blk_flush(BlockBackend *blk);
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int blk_commit_all(void);
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void blk_inc_in_flight(BlockBackend *blk);
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void blk_dec_in_flight(BlockBackend *blk);
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void blk_drain(BlockBackend *blk);
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void blk_drain_all(void);
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void blk_set_on_error(BlockBackend *blk, BlockdevOnError on_read_error,
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BlockdevOnError on_write_error);
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BlockdevOnError blk_get_on_error(BlockBackend *blk, bool is_read);
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BlockErrorAction blk_get_error_action(BlockBackend *blk, bool is_read,
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int error);
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void blk_error_action(BlockBackend *blk, BlockErrorAction action,
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bool is_read, int error);
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bool blk_supports_write_perm(BlockBackend *blk);
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bool blk_is_writable(BlockBackend *blk);
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bool blk_is_sg(BlockBackend *blk);
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bool blk_enable_write_cache(BlockBackend *blk);
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void blk_set_enable_write_cache(BlockBackend *blk, bool wce);
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void blk_invalidate_cache(BlockBackend *blk, Error **errp);
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bool blk_is_inserted(BlockBackend *blk);
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bool blk_is_available(BlockBackend *blk);
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void blk_lock_medium(BlockBackend *blk, bool locked);
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void blk_eject(BlockBackend *blk, bool eject_flag);
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int blk_get_flags(BlockBackend *blk);
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uint32_t blk_get_request_alignment(BlockBackend *blk);
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uint32_t blk_get_max_transfer(BlockBackend *blk);
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int blk_get_max_iov(BlockBackend *blk);
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void blk_set_guest_block_size(BlockBackend *blk, int align);
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void *blk_try_blockalign(BlockBackend *blk, size_t size);
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void *blk_blockalign(BlockBackend *blk, size_t size);
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bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp);
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void blk_op_unblock(BlockBackend *blk, BlockOpType op, Error *reason);
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void blk_op_block_all(BlockBackend *blk, Error *reason);
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void blk_op_unblock_all(BlockBackend *blk, Error *reason);
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AioContext *blk_get_aio_context(BlockBackend *blk);
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int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
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Error **errp);
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void blk_add_aio_context_notifier(BlockBackend *blk,
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void (*attached_aio_context)(AioContext *new_context, void *opaque),
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void (*detach_aio_context)(void *opaque), void *opaque);
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void blk_remove_aio_context_notifier(BlockBackend *blk,
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void (*attached_aio_context)(AioContext *,
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void *),
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void (*detach_aio_context)(void *),
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void *opaque);
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void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify);
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void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify);
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void blk_io_plug(BlockBackend *blk);
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void blk_io_unplug(BlockBackend *blk);
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BlockAcctStats *blk_get_stats(BlockBackend *blk);
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BlockBackendRootState *blk_get_root_state(BlockBackend *blk);
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void blk_update_root_state(BlockBackend *blk);
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bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk);
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int blk_get_open_flags_from_root_state(BlockBackend *blk);
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void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
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BlockCompletionFunc *cb, void *opaque);
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int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
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int bytes, BdrvRequestFlags flags);
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int blk_pwrite_compressed(BlockBackend *blk, int64_t offset, const void *buf,
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int bytes);
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int blk_truncate(BlockBackend *blk, int64_t offset, bool exact,
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PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
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int blk_pdiscard(BlockBackend *blk, int64_t offset, int bytes);
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int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,
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int64_t pos, int size);
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int blk_load_vmstate(BlockBackend *blk, uint8_t *buf, int64_t pos, int size);
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int blk_probe_blocksizes(BlockBackend *blk, BlockSizes *bsz);
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int blk_probe_geometry(BlockBackend *blk, HDGeometry *geo);
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BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
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BlockCompletionFunc *cb,
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void *opaque, int ret);
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void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg);
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void blk_io_limits_disable(BlockBackend *blk);
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void blk_io_limits_enable(BlockBackend *blk, const char *group);
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void blk_io_limits_update_group(BlockBackend *blk, const char *group);
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void blk_set_force_allow_inactivate(BlockBackend *blk);
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void blk_register_buf(BlockBackend *blk, void *host, size_t size);
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void blk_unregister_buf(BlockBackend *blk, void *host);
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int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
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BlockBackend *blk_out, int64_t off_out,
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int bytes, BdrvRequestFlags read_flags,
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BdrvRequestFlags write_flags);
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const BdrvChild *blk_root(BlockBackend *blk);
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int blk_make_empty(BlockBackend *blk, Error **errp);
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#endif
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