ceph: return -EINVAL if given fsc mount option on kernel w/o support

If someone requests fscache on the mount, and the kernel doesn't
support it, it should fail the mount.

[ Drop ceph prefix -- it's provided by pr_err. ]
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/super.c

@@ -268,6 +268,7 @@ static int parse_fsopt_token(char *c, void *private)
 		}
 		break;
 	case Opt_fscache_uniq:
+#ifdef CONFIG_CEPH_FSCACHE
 		kfree(fsopt->fscache_uniq);
 		fsopt->fscache_uniq = kstrndup(argstr[0].from,
 					       argstr[0].to-argstr[0].from,
@@ -276,7 +277,10 @@ static int parse_fsopt_token(char *c, void *private)
 			return -ENOMEM;
 		fsopt->flags |= CEPH_MOUNT_OPT_FSCACHE;
 		break;
-		/* misc */
+#else
+		pr_err("fscache support is disabled\n");
+		return -EINVAL;
+#endif
 	case Opt_wsize:
 		if (intval < (int)PAGE_SIZE || intval > CEPH_MAX_WRITE_SIZE)
 			return -EINVAL;
@@ -353,10 +357,15 @@ static int parse_fsopt_token(char *c, void *private)
 		fsopt->flags &= ~CEPH_MOUNT_OPT_INO32;
 		break;
 	case Opt_fscache:
+#ifdef CONFIG_CEPH_FSCACHE
 		fsopt->flags |= CEPH_MOUNT_OPT_FSCACHE;
 		kfree(fsopt->fscache_uniq);
 		fsopt->fscache_uniq = NULL;
 		break;
+#else
+		pr_err("fscache support is disabled\n");
+		return -EINVAL;
+#endif
 	case Opt_nofscache:
 		fsopt->flags &= ~CEPH_MOUNT_OPT_FSCACHE;
 		kfree(fsopt->fscache_uniq);