vfs: make sync_filesystem return errors from ->sync_fs

stable inclusion
from stable-v5.10.140
commit 76a51e49da9c9919b97225982d720da5315ebaa7
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I63FTT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=76a51e49da9c9919b97225982d720da5315ebaa7

--------------------------------

commit 5679897e upstream.

[backport to 5.10 only differs in __sync_blockdev helper]

Strangely, sync_filesystem ignores the return code from the ->sync_fs
call, which means that syscalls like syncfs(2) never see the error.
This doesn't seem right, so fix that.
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NChristian Brauner <brauner@kernel.org>
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Acked-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

fs/sync.c

@@ -28,7 +28,7 @@
  */
 int sync_filesystem(struct super_block *sb)
 {
-	int ret;
+	int ret = 0;
 
 	/*
 	 * We need to be protected against the filesystem going from
@@ -51,15 +51,21 @@ int sync_filesystem(struct super_block *sb)
 	 * at a time.
 	 */
 	writeback_inodes_sb(sb, WB_REASON_SYNC);
-	if (sb->s_op->sync_fs)
-		sb->s_op->sync_fs(sb, 0);
+	if (sb->s_op->sync_fs) {
+		ret = sb->s_op->sync_fs(sb, 0);
+		if (ret)
+			return ret;
+	}
 	ret = __sync_blockdev(sb->s_bdev, 0);
-	if (ret < 0)
+	if (ret)
 		return ret;
 
 	sync_inodes_sb(sb);
-	if (sb->s_op->sync_fs)
-		sb->s_op->sync_fs(sb, 1);
+	if (sb->s_op->sync_fs) {
+		ret = sb->s_op->sync_fs(sb, 1);
+		if (ret)
+			return ret;
+	}
 	return __sync_blockdev(sb->s_bdev, 1);
 }
 EXPORT_SYMBOL(sync_filesystem);