ceph: flush dirty inodes before proceeding with remount

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@vger.kernel.org
Link: http://tracker.ceph.com/issues/39571
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 6d5bb2f74612..01113c86e469 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -845,6 +845,12 @@ static void ceph_umount_begin(struct super_block *sb)
         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,
@@ -852,6 +858,7 @@ static const struct super_operations ceph_super_ops = {
         .drop_inode     = ceph_drop_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,