[PATCH 4.9 002/117] fs/fat/file.c: issue flush after the writeback of FAT

[Greg Kroah-Hartman]

[ Upstream commit bd8309de0d60838eef6fb575b0c4c7e95841cf73 ]

fsync() needs to make sure the data & meta-data of file are persistent
after the return of fsync(), even when a power-failure occurs later.  In
the case of fat-fs, the FAT belongs to the meta-data of file, so we need
to issue a flush after the writeback of FAT instead before.

Also bail out early when any stage of fsync fails.

Link: http://lkml.kernel.org/r/20190409030158.136316-1-houtao1@xxxxxxxxxx
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/fat/file.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 3d04b124bce0..392ec5641f38 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -160,12 +160,17 @@ static int fat_file_release(struct inode *inode, struct file *filp)
 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 {
 	struct inode *inode = filp->f_mapping->host;
-	int res, err;
+	int err;
+
+	err = __generic_file_fsync(filp, start, end, datasync);
+	if (err)
+		return err;
 
-	res = generic_file_fsync(filp, start, end, datasync);
 	err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
+	if (err)
+		return err;
 
-	return res ? res : err;
+	return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 }
 
 
-- 
2.20.1