ceph: send LSSNAP request to auth mds of directory inode

Snapdir inode has no capability. __choose_mds() should choose mds
base on capabilities of snapdir's parent inode.
Signed-off-by: N"Yan, Zheng" <zyan@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

fs/ceph/dir.c

@@ -377,8 +377,10 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 		}
 		/* hints to request -> mds selection code */
 		req->r_direct_mode = USE_AUTH_MDS;
-		req->r_direct_hash = ceph_frag_value(frag);
-		__set_bit(CEPH_MDS_R_DIRECT_IS_HASH, &req->r_req_flags);
+		if (op == CEPH_MDS_OP_READDIR) {
+			req->r_direct_hash = ceph_frag_value(frag);
+			__set_bit(CEPH_MDS_R_DIRECT_IS_HASH, &req->r_req_flags);
+		}
 		if (fi->last_name) {
 			req->r_path2 = kstrdup(fi->last_name, GFP_KERNEL);
 			if (!req->r_path2) {

fs/ceph/mds_client.c

@@ -731,9 +731,16 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
 
 	inode = NULL;
 	if (req->r_inode) {
-		inode = req->r_inode;
-		ihold(inode);
-	} else if (req->r_dentry) {
+		if (ceph_snap(req->r_inode) != CEPH_SNAPDIR) {
+			inode = req->r_inode;
+			ihold(inode);
+		} else {
+			/* req->r_dentry is non-null for LSSNAP request.
+			 * fall-thru */
+			WARN_ON_ONCE(!req->r_dentry);
+		}
+	}
+	if (!inode && req->r_dentry) {
 		/* ignore race with rename; old or new d_parent is okay */
 		struct dentry *parent;
 		struct inode *dir;