f2fs: avoid race in between atomic_read & atomic_inc

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Previously, we will miss merging flush command during fsync due to below
race condition:

Thread A 		Thread B		Thread C
- f2fs_issue_flush
 - atomic_read(&issing_flush)
			- f2fs_issue_flush
			 - atomic_read(&issing_flush)
						- f2fs_issue_flush
						 - atomic_read(&issing_flush)
  - atomic_inc(&issing_flush)
			  - atomic_inc(&issing_flush)
						  - atomic_inc(&issing_flush)
   - submit_flush_wait
			   - submit_flush_wait
						   - submit_flush_wait

It needs to use atomic_inc_return instead to avoid such race.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

...

This commit is contained in:

Chao Yu 2017-08-31 18:56:05 +08:00 • committed by Jaegeuk Kim

parent 025d63a486

commit edd748e6c8

1 changed files with 1 additions and 3 deletions

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fs/f2fs/segment.c

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