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| author | Chao Yu <chao@kernel.org> | 2022-01-27 06:44:49 +0100 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2022-03-03 22:30:48 +0100 |
| commit | 344150999b7fc88502a65bbb147a47503eca2033 (patch) | |
| tree | b08c9a7d20bc86fb2aaa3d38605639a3e613997b /fs/f2fs/node.c | |
| parent | f2fs: quota: fix loop condition at f2fs_quota_sync() (diff) | |
| download | linux-344150999b7fc88502a65bbb147a47503eca2033.tar.xz linux-344150999b7fc88502a65bbb147a47503eca2033.zip | |
f2fs: fix to avoid potential deadlock
Quoted from Jing Xia's report, there is a potential deadlock may happen
between kworker and checkpoint as below:
[T:writeback] [T:checkpoint]
- wb_writeback
- blk_start_plug
bio contains NodeA was plugged in writeback threads
- do_writepages -- sync write inodeB, inc wb_sync_req[DATA]
- f2fs_write_data_pages
- f2fs_write_single_data_page -- write last dirty page
- f2fs_do_write_data_page
- set_page_writeback -- clear page dirty flag and
PAGECACHE_TAG_DIRTY tag in radix tree
- f2fs_outplace_write_data
- f2fs_update_data_blkaddr
- f2fs_wait_on_page_writeback -- wait NodeA to writeback here
- inode_dec_dirty_pages
- writeback_sb_inodes
- writeback_single_inode
- do_writepages
- f2fs_write_data_pages -- skip writepages due to wb_sync_req[DATA]
- wbc->pages_skipped += get_dirty_pages() -- PAGECACHE_TAG_DIRTY is not set but get_dirty_pages() returns one
- requeue_inode -- requeue inode to wb->b_dirty queue due to non-zero.pages_skipped
- blk_finish_plug
Let's try to avoid deadlock condition by forcing unplugging previous bio via
blk_finish_plug(current->plug) once we'v skipped writeback in writepages()
due to valid sbi->wb_sync_req[DATA/NODE].
Fixes: 687de7f1010c ("f2fs: avoid IO split due to mixed WB_SYNC_ALL and WB_SYNC_NONE")
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Signed-off-by: Jing Xia <jing.xia@unisoc.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/node.c')
| -rw-r--r-- | fs/f2fs/node.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index 0d9883457579..fe8c38c9ac77 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -2112,8 +2112,12 @@ static int f2fs_write_node_pages(struct address_space *mapping, if (wbc->sync_mode == WB_SYNC_ALL) atomic_inc(&sbi->wb_sync_req[NODE]); - else if (atomic_read(&sbi->wb_sync_req[NODE])) + else if (atomic_read(&sbi->wb_sync_req[NODE])) { + /* to avoid potential deadlock */ + if (current->plug) + blk_finish_plug(current->plug); goto skip_write; + } trace_f2fs_writepages(mapping->host, wbc, NODE); |