ceph: tolerate (and warn on) extraneous dentry from mds

If the MDS gives us a dentry and we weren't prepared to handle it,
WARN_ON_ONCE instead of crashing.

Reported-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 9fff9f3b17e4..4b5762ef7c2b 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -992,11 +992,15 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
         if (rinfo->head->is_dentry) {
                 struct inode *dir = req->r_locked_dir;
 
-                err = fill_inode(dir, &rinfo->diri, rinfo->dirfrag,
-                                 session, req->r_request_started, -1,
-                                 &req->r_caps_reservation);
-                if (err < 0)
-                        return err;
+                if (dir) {
+                        err = fill_inode(dir, &rinfo->diri, rinfo->dirfrag,
+                                         session, req->r_request_started, -1,
+                                         &req->r_caps_reservation);
+                        if (err < 0)
+                                return err;
+                } else {
+                        WARN_ON_ONCE(1);
+                }
         }
 
         /*
@@ -1004,6 +1008,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
          * will have trouble splicing in the virtual snapdir later
          */
         if (rinfo->head->is_dentry && !req->r_aborted &&
+            req->r_locked_dir &&
             (rinfo->head->is_target || strncmp(req->r_dentry->d_name.name,
                                                fsc->mount_options->snapdir_name,
                                                req->r_dentry->d_name.len))) {