Commit 27319ba4 authored Apr 17, 2018 by Chao Yu Committed by Jaegeuk Kim May 31, 2018

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>

parent ea4d479b

fs/f2fs/file.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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 @@ inc_stat:
		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;

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