ext4: track writeback errors using the generic tracking infrastructure

commit 95cb67138746451cc84cf8e516e14989746e93b0 upstream.

We already using mapping_set_error() in fs/ext4/page_io.c, so all we
need to do is to use file_check_and_advance_wb_err() when handling
fsync() requests in ext4_sync_file().

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 87a7ff0..712f009 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -164,6 +164,9 @@
 			ret = err;
 	}
 out:
+	err = file_check_and_advance_wb_err(file);
+	if (ret == 0)
+		ret = err;
 	trace_ext4_sync_file_exit(inode, ret);
 	return ret;
 }