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f2fs: fix race in between GC and atomic open 

Thread					GC thread
- f2fs_ioc_start_atomic_write
 - get_dirty_pages
 - filemap_write_and_wait_range
					- f2fs_gc
					 - do_garbage_collect
					  - gc_data_segment
					   - move_data_page
					    - f2fs_is_atomic_file
					    - set_page_dirty
 - set_inode_flag(, FI_ATOMIC_FILE)

Dirty data page can still be generated by GC in race condition as
above call stack.

This patch adds fi->dio_rwsem[WRITE] in f2fs_ioc_start_atomic_write
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 2018-04-17 17:51:28 +08:00 committed by Jaegeuk Kim
parent ea4d479bb3
commit 27319ba404
1 changed files with 3 additions and 0 deletions
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3
fs/f2fs/file.c
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@ -1677,6 +1677,8 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
inode_lock(inode);
down_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
if (f2fs_is_atomic_file(inode))
goto out;
@ -1706,6 +1708,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
stat_inc_atomic_write(inode);
stat_update_max_atomic_write(inode);
out:
up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
inode_unlock(inode);
mnt_drop_write_file(filp);
return ret;