Two fixups for CephFS snapshot-handling patches in -rc1.

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Merge tag 'ceph-for-4.14-rc4' of git://github.com/ceph/ceph-client

Pull ceph fixes from Ilya Dryomov:
 "Two fixups for CephFS snapshot-handling patches in -rc1"

* tag 'ceph-for-4.14-rc4' of git://github.com/ceph/ceph-client:
  ceph: fix __choose_mds() for LSSNAP request
  ceph: properly queue cap snap for newly created snap realm

fs/ceph/mds_client.c

@@ -734,12 +734,13 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
 			inode = req->r_inode;
 			ihold(inode);
 		} else {
-			/* req->r_dentry is non-null for LSSNAP request.
-			 * fall-thru */
-			WARN_ON_ONCE(!req->r_dentry);
+			/* req->r_dentry is non-null for LSSNAP request */
+			rcu_read_lock();
+			inode = get_nonsnap_parent(req->r_dentry);
+			rcu_read_unlock();
+			dout("__choose_mds using snapdir's parent %p\n", inode);
 		}
-	}
-	if (!inode && req->r_dentry) {
+	} else if (req->r_dentry) {
 		/* ignore race with rename; old or new d_parent is okay */
 		struct dentry *parent;
 		struct inode *dir;

fs/ceph/snap.c

@@ -374,12 +374,10 @@ static int build_snap_context(struct ceph_snap_realm *realm,
 	     realm->ino, realm, snapc, snapc->seq,
 	     (unsigned int) snapc->num_snaps);
 
-	if (realm->cached_context) {
-		ceph_put_snap_context(realm->cached_context);
-		/* queue realm for cap_snap creation */
-		list_add_tail(&realm->dirty_item, dirty_realms);
-	}
+	ceph_put_snap_context(realm->cached_context);
 	realm->cached_context = snapc;
+	/* queue realm for cap_snap creation */
+	list_add_tail(&realm->dirty_item, dirty_realms);
 	return 0;
 
 fail: