FAILED: patch "[PATCH] ext4: track writeback errors using the generic tracking" failed to apply to 3.18-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 95cb67138746451cc84cf8e516e14989746e93b0 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 31 Dec 2018 00:11:07 -0500
Subject: [PATCH] ext4: track writeback errors using the generic tracking
 infrastructure

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

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 87a7ff00ef62..712f00995390 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -164,6 +164,9 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 			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;
 }