f2fs: correct i_size change for atomic writes

f2fs: correct i_size change for atomic writes

[ Upstream commit 02fd88ebbcae838d10cb12adff480eed3cb21b14 ]

We need to make sure i_size doesn't change until atomic write commit is
successful and restore it when commit is failed.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: a2665a1af8c3 ("f2fs: clear atomic_write_task in f2fs_abort_atomic_write()")
Signed-off-by: Sasha Levin <sashal@kernel.org>