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

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>

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/fat/file.c b/fs/fat/file.c
index b3bed32946b1..0e3ed79fcc3f 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -193,12 +193,17 @@ 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);
 }