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c86422c554
BlockDriver->bdrv_getlength is categorized as IO callback, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since the callback traverses the block nodes graph, which however is only possible in a coroutine. Therefore turn it into a co_wrapper to move the actual function into a coroutine where the lock can be taken. Because now this function creates a new coroutine and polls, we need to take the AioContext lock where it is missing, for the only reason that internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the AioContext lock. This is especially messy when a co_wrapper creates a coroutine and polls in bdrv_open_driver, because this function has so many callers in so many context that it can easily lead to deadlocks. Therefore the new rule for bdrv_open_driver is that the caller must always hold the AioContext lock of the given bs (except if it is a coroutine), because the function calls bdrv_refresh_total_sectors() which is now a co_wrapper. Once the rwlock is ultimated and placed in every place it needs to be, we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext lock. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20230113204212.359076-7-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
202 lines
9.2 KiB
C
202 lines
9.2 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_IO_H
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#define BLOCK_BACKEND_IO_H
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#include "block-backend-common.h"
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#include "block/accounting.h"
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/*
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* I/O API functions. These functions are thread-safe.
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*
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* See include/block/block-io.h for more information about
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* the I/O API.
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*/
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const char *blk_name(const BlockBackend *blk);
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BlockDriverState *blk_bs(BlockBackend *blk);
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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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bool blk_iostatus_is_enabled(const BlockBackend *blk);
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char *blk_get_attached_dev_id(BlockBackend *blk);
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BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
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int64_t bytes, BdrvRequestFlags flags,
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BlockCompletionFunc *cb, void *opaque);
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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, int64_t bytes,
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BlockCompletionFunc *cb, void *opaque);
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void blk_aio_cancel_async(BlockAIOCB *acb);
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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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void blk_inc_in_flight(BlockBackend *blk);
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void blk_dec_in_flight(BlockBackend *blk);
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bool coroutine_fn blk_co_is_inserted(BlockBackend *blk);
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bool co_wrapper_mixed 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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int64_t coroutine_fn blk_co_getlength(BlockBackend *blk);
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int64_t co_wrapper_mixed 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 coroutine_fn blk_co_nb_sectors(BlockBackend *blk);
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int64_t co_wrapper_mixed blk_nb_sectors(BlockBackend *blk);
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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_is_writable(BlockBackend *blk);
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bool blk_enable_write_cache(BlockBackend *blk);
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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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void blk_iostatus_set_err(BlockBackend *blk, int error);
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int blk_get_max_iov(BlockBackend *blk);
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int blk_get_max_hw_iov(BlockBackend *blk);
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void coroutine_fn blk_co_io_plug(BlockBackend *blk);
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void co_wrapper blk_io_plug(BlockBackend *blk);
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void coroutine_fn blk_co_io_unplug(BlockBackend *blk);
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void co_wrapper blk_io_unplug(BlockBackend *blk);
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AioContext *blk_get_aio_context(BlockBackend *blk);
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BlockAcctStats *blk_get_stats(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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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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uint32_t blk_get_request_alignment(BlockBackend *blk);
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uint32_t blk_get_max_transfer(BlockBackend *blk);
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uint64_t blk_get_max_hw_transfer(BlockBackend *blk);
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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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int64_t bytes, BdrvRequestFlags read_flags,
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BdrvRequestFlags write_flags);
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int coroutine_fn blk_co_block_status_above(BlockBackend *blk,
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BlockDriverState *base,
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int64_t offset, int64_t bytes,
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int64_t *pnum, int64_t *map,
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BlockDriverState **file);
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int coroutine_fn blk_co_is_allocated_above(BlockBackend *blk,
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BlockDriverState *base,
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bool include_base, int64_t offset,
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int64_t bytes, int64_t *pnum);
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/*
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* "I/O or GS" API functions. These functions can run without
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* the BQL, but only in one specific iothread/main loop.
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*
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* See include/block/block-io.h for more information about
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* the "I/O or GS" API.
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*/
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int co_wrapper_mixed blk_pread(BlockBackend *blk, int64_t offset,
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int64_t bytes, void *buf,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_pread(BlockBackend *blk, int64_t offset, int64_t bytes,
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void *buf, BdrvRequestFlags flags);
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int co_wrapper_mixed blk_preadv(BlockBackend *blk, int64_t offset,
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int64_t bytes, QEMUIOVector *qiov,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
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int64_t bytes, QEMUIOVector *qiov,
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BdrvRequestFlags flags);
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int co_wrapper_mixed blk_preadv_part(BlockBackend *blk, int64_t offset,
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int64_t bytes, QEMUIOVector *qiov,
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size_t qiov_offset,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_preadv_part(BlockBackend *blk, int64_t offset,
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int64_t bytes, QEMUIOVector *qiov,
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size_t qiov_offset, BdrvRequestFlags flags);
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int co_wrapper_mixed blk_pwrite(BlockBackend *blk, int64_t offset,
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int64_t bytes, const void *buf,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_pwrite(BlockBackend *blk, int64_t offset, int64_t bytes,
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const void *buf, BdrvRequestFlags flags);
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int co_wrapper_mixed blk_pwritev(BlockBackend *blk, int64_t offset,
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int64_t bytes, QEMUIOVector *qiov,
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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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int64_t bytes, QEMUIOVector *qiov,
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BdrvRequestFlags flags);
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int co_wrapper_mixed blk_pwritev_part(BlockBackend *blk, int64_t offset,
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int64_t bytes, QEMUIOVector *qiov,
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size_t qiov_offset,
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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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int64_t bytes,
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QEMUIOVector *qiov, size_t qiov_offset,
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BdrvRequestFlags flags);
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int co_wrapper_mixed blk_pwrite_compressed(BlockBackend *blk,
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int64_t offset, int64_t bytes,
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const void *buf);
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int coroutine_fn blk_co_pwrite_compressed(BlockBackend *blk, int64_t offset,
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int64_t bytes, const void *buf);
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int co_wrapper_mixed blk_pwrite_zeroes(BlockBackend *blk, int64_t offset,
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int64_t bytes,
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BdrvRequestFlags flags);
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int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
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int64_t bytes, BdrvRequestFlags flags);
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int co_wrapper_mixed blk_pdiscard(BlockBackend *blk, int64_t offset,
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int64_t bytes);
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int coroutine_fn blk_co_pdiscard(BlockBackend *blk, int64_t offset,
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int64_t bytes);
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int co_wrapper_mixed blk_flush(BlockBackend *blk);
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int coroutine_fn blk_co_flush(BlockBackend *blk);
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int co_wrapper_mixed blk_ioctl(BlockBackend *blk, unsigned long int req,
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void *buf);
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int coroutine_fn blk_co_ioctl(BlockBackend *blk, unsigned long int req,
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void *buf);
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int co_wrapper_mixed blk_truncate(BlockBackend *blk, int64_t offset,
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bool exact, PreallocMode prealloc,
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BdrvRequestFlags flags, Error **errp);
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int coroutine_fn blk_co_truncate(BlockBackend *blk, int64_t offset, bool exact,
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PreallocMode prealloc, BdrvRequestFlags flags,
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Error **errp);
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#endif /* BLOCK_BACKEND_IO_H */
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