fs/fat/file.c: issue flush after the writeback of FAT

BugLink: https://bugs.launchpad.net/bugs/1838824
[ 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@huawei.com
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4724cc9ad65021c8fe80a3cc66783e8d01801907..62581de09bf1d3c8ebdcbbdf26b7d3d5d93420ff 100644 (file)
--- 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);
 }