ceph: don't check quota for snap inode

snap inode's i_snap_realm is not pointing to ceph_snap_realm.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/dir.c

@@ -936,7 +936,8 @@ static int ceph_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 		goto out;
 	}
 
-	if (ceph_quota_is_max_files_exceeded(dir)) {
+	if (op == CEPH_MDS_OP_MKDIR &&
+	    ceph_quota_is_max_files_exceeded(dir)) {
 		err = -EDQUOT;
 		goto out;
 	}

fs/ceph/quota.c

@@ -86,8 +86,15 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
 	struct ceph_vino vino;
 	struct inode *in;
 
+	if (ceph_snap(inode) != CEPH_NOSNAP)
+		return NULL;
+
 	realm = ceph_inode(inode)->i_snap_realm;
+	if (realm)
 		ceph_get_snap_realm(mdsc, realm);
+	else
+		pr_err_ratelimited("get_quota_realm: ino (%llx.%llx) "
+				   "null i_snap_realm\n", ceph_vinop(inode));
 	while (realm) {
 		vino.ino = realm->ino;
 		vino.snap = CEPH_NOSNAP;
@@ -158,9 +165,16 @@ static bool check_quota_exceeded(struct inode *inode, enum quota_check_op op,
 	bool is_root;
 	bool exceeded = false;
 
+	if (ceph_snap(inode) != CEPH_NOSNAP)
+		return false;
+
 	down_read(&mdsc->snap_rwsem);
 	realm = ceph_inode(inode)->i_snap_realm;
+	if (realm)
 		ceph_get_snap_realm(mdsc, realm);
+	else
+		pr_err_ratelimited("check_quota_exceeded: ino (%llx.%llx) "
+				   "null i_snap_realm\n", ceph_vinop(inode));
 	while (realm) {
 		vino.ino = realm->ino;
 		vino.snap = CEPH_NOSNAP;