f2fs: compress: fix potential deadlock

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[ Upstream commit 3afae09ffe ]

generic/269 reports a hangtask issue, the root cause is ABBA deadlock
described as below:

Thread A			Thread B
- down_write(&sbi->gc_lock) -- A
				- f2fs_write_data_pages
				 - lock all pages in cluster -- B
				 - f2fs_write_multi_pages
				  - f2fs_write_raw_pages
				   - f2fs_write_single_data_page
				    - f2fs_balance_fs
				     - down_write(&sbi->gc_lock) -- A
- f2fs_gc
 - do_garbage_collect
  - ra_data_block
   - pagecache_get_page -- B

To fix this, it needs to avoid calling f2fs_balance_fs() if there is
still cluster pages been locked in context of cluster writeback, so
instead, let's call f2fs_balance_fs() in the end of
f2fs_write_raw_pages() when all cluster pages were unlocked.

Fixes: 4c8ff7095b ("f2fs: support data compression")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Chao Yu 2021-01-11 17:42:53 +08:00 • committed by Greg Kroah-Hartman

parent 91e10f2ad1

commit 2bebc6dcd3

3 changed files with 11 additions and 6 deletions

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5

fs/f2fs/compress.c

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10

fs/f2fs/data.c

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2

fs/f2fs/f2fs.h

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