[PATCH] f2fs: fix to force keeping write barrier for strict fsync mode

[Chao Yu]

If barrier is enabled, for strict fsync mode, we should force to
use atomic write semantics to avoid data corruption due to no
barrier support in lower device.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
 fs/f2fs/file.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 86ddbb55d2b1..c9dd45f82fbd 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -241,6 +241,13 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
 	};
 	unsigned int seq_id = 0;
 
+	/*
+	 * for strict fsync mode, force to keep atomic write sematics to avoid
+	 * data corruption if lower device doesn't support write barrier.
+	 */
+	if (!atomic && F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_STRICT)
+		atomic = true;
+
 	if (unlikely(f2fs_readonly(inode->i_sb) ||
 				is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
 		return 0;
-- 
2.18.0.rc1