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d483001206
As described in commit8111964f1b("dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata"), ABBA deadlocks will be triggered because shrinker_rwsem currently needs to held by dm_pool_abort_metadata() as a side-effect of thin-pool metadata operation failure. The following three problem scenarios have been noticed: 1) Described by commit8111964f1b("dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata") 2) shrinker_rwsem and throttle->lock P1(drop cache) P2(kworker) drop_caches_sysctl_handler drop_slab shrink_slab down_read(&shrinker_rwsem) - LOCK A do_shrink_slab super_cache_scan prune_icache_sb dispose_list evict ext4_evict_inode ext4_clear_inode ext4_discard_preallocations ext4_mb_load_buddy_gfp ext4_mb_init_cache ext4_wait_block_bitmap __ext4_error ext4_handle_error ext4_commit_super ... dm_submit_bio do_worker throttle_work_update down_write(&t->lock) -- LOCK B process_deferred_bios commit metadata_operation_failed dm_pool_abort_metadata dm_block_manager_create dm_bufio_client_create register_shrinker down_write(&shrinker_rwsem) -- LOCK A thin_map thin_bio_map thin_defer_bio_with_throttle throttle_lock down_read(&t->lock) - LOCK B 3) shrinker_rwsem and wait_on_buffer P1(drop cache) P2(kworker) drop_caches_sysctl_handler drop_slab shrink_slab down_read(&shrinker_rwsem) - LOCK A do_shrink_slab ... ext4_wait_block_bitmap __ext4_error ext4_handle_error jbd2_journal_abort jbd2_journal_update_sb_errno jbd2_write_superblock submit_bh // LOCK B // RELEASE B do_worker throttle_work_update down_write(&t->lock) - LOCK B process_deferred_bios process_bio commit metadata_operation_failed dm_pool_abort_metadata dm_block_manager_create dm_bufio_client_create register_shrinker register_shrinker_prepared down_write(&shrinker_rwsem) - LOCK A bio_endio wait_on_buffer __wait_on_buffer Fix these by resetting dm_bufio_client without holding shrinker_rwsem. Fixes:8111964f1b("dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata") Cc: stable@vger.kernel.org Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
164 lines
4.9 KiB
C
164 lines
4.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2009-2011 Red Hat, Inc.
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*
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* Author: Mikulas Patocka <mpatocka@redhat.com>
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*
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* This file is released under the GPL.
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*/
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#ifndef _LINUX_DM_BUFIO_H
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#define _LINUX_DM_BUFIO_H
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#include <linux/blkdev.h>
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#include <linux/types.h>
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/*----------------------------------------------------------------*/
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struct dm_bufio_client;
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struct dm_buffer;
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/*
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* Flags for dm_bufio_client_create
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*/
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#define DM_BUFIO_CLIENT_NO_SLEEP 0x1
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/*
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* Create a buffered IO cache on a given device
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*/
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struct dm_bufio_client *
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dm_bufio_client_create(struct block_device *bdev, unsigned int block_size,
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unsigned int reserved_buffers, unsigned int aux_size,
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void (*alloc_callback)(struct dm_buffer *),
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void (*write_callback)(struct dm_buffer *),
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unsigned int flags);
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/*
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* Release a buffered IO cache.
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*/
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void dm_bufio_client_destroy(struct dm_bufio_client *c);
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void dm_bufio_client_reset(struct dm_bufio_client *c);
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/*
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* Set the sector range.
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* When this function is called, there must be no I/O in progress on the bufio
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* client.
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*/
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void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start);
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/*
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* WARNING: to avoid deadlocks, these conditions are observed:
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*
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* - At most one thread can hold at most "reserved_buffers" simultaneously.
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* - Each other threads can hold at most one buffer.
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* - Threads which call only dm_bufio_get can hold unlimited number of
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* buffers.
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*/
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/*
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* Read a given block from disk. Returns pointer to data. Returns a
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* pointer to dm_buffer that can be used to release the buffer or to make
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* it dirty.
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*/
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void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
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struct dm_buffer **bp);
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/*
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* Like dm_bufio_read, but return buffer from cache, don't read
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* it. If the buffer is not in the cache, return NULL.
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*/
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void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
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struct dm_buffer **bp);
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/*
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* Like dm_bufio_read, but don't read anything from the disk. It is
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* expected that the caller initializes the buffer and marks it dirty.
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*/
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void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
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struct dm_buffer **bp);
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/*
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* Prefetch the specified blocks to the cache.
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* The function starts to read the blocks and returns without waiting for
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* I/O to finish.
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*/
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void dm_bufio_prefetch(struct dm_bufio_client *c,
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sector_t block, unsigned int n_blocks);
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/*
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* Release a reference obtained with dm_bufio_{read,get,new}. The data
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* pointer and dm_buffer pointer is no longer valid after this call.
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*/
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void dm_bufio_release(struct dm_buffer *b);
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/*
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* Mark a buffer dirty. It should be called after the buffer is modified.
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*
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* In case of memory pressure, the buffer may be written after
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* dm_bufio_mark_buffer_dirty, but before dm_bufio_write_dirty_buffers. So
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* dm_bufio_write_dirty_buffers guarantees that the buffer is on-disk but
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* the actual writing may occur earlier.
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*/
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void dm_bufio_mark_buffer_dirty(struct dm_buffer *b);
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/*
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* Mark a part of the buffer dirty.
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*
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* The specified part of the buffer is scheduled to be written. dm-bufio may
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* write the specified part of the buffer or it may write a larger superset.
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*/
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void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
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unsigned int start, unsigned int end);
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/*
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* Initiate writing of dirty buffers, without waiting for completion.
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*/
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void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c);
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/*
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* Write all dirty buffers. Guarantees that all dirty buffers created prior
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* to this call are on disk when this call exits.
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*/
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int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c);
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/*
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* Send an empty write barrier to the device to flush hardware disk cache.
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*/
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int dm_bufio_issue_flush(struct dm_bufio_client *c);
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/*
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* Send a discard request to the underlying device.
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*/
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int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count);
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/*
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* Free the given buffer.
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* This is just a hint, if the buffer is in use or dirty, this function
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* does nothing.
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*/
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void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);
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/*
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* Free the given range of buffers.
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* This is just a hint, if the buffer is in use or dirty, this function
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* does nothing.
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*/
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void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks);
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/*
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* Set the minimum number of buffers before cleanup happens.
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*/
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void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n);
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unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c);
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sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
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struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c);
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sector_t dm_bufio_get_block_number(struct dm_buffer *b);
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void *dm_bufio_get_block_data(struct dm_buffer *b);
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void *dm_bufio_get_aux_data(struct dm_buffer *b);
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struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b);
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/*----------------------------------------------------------------*/
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#endif
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