[PATCH 4.9 23/53] ceph: flush dirty inodes before proceeding with remount

[Greg Kroah-Hartman]

From: Jeff Layton <jlayton@xxxxxxxxxx>

commit 00abf69dd24f4444d185982379c5cc3bb7b6d1fc upstream.

xfstest generic/452 was triggering a "Busy inodes after umount" warning.
ceph was allowing the mount to go read-only without first flushing out
dirty inodes in the cache. Ensure we sync out the filesystem before
allowing a remount to proceed.

Cc: stable@xxxxxxxxxxxxxxx
Link: http://tracker.ceph.com/issues/39571
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Reviewed-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ceph/super.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -742,6 +742,12 @@ static void ceph_umount_begin(struct sup
 	return;
 }
 
+static int ceph_remount(struct super_block *sb, int *flags, char *data)
+{
+	sync_filesystem(sb);
+	return 0;
+}
+
 static const struct super_operations ceph_super_ops = {
 	.alloc_inode	= ceph_alloc_inode,
 	.destroy_inode	= ceph_destroy_inode,
@@ -750,6 +756,7 @@ static const struct super_operations cep
 	.evict_inode	= ceph_evict_inode,
 	.sync_fs        = ceph_sync_fs,
 	.put_super	= ceph_put_super,
+	.remount_fs	= ceph_remount,
 	.show_options   = ceph_show_options,
 	.statfs		= ceph_statfs,
 	.umount_begin   = ceph_umount_begin,