Fix btrfs_fill_super to return -EINVAL when no FS found

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/disk-io.c

@@ -728,9 +728,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 	struct btrfs_root *dev_root = kmalloc(sizeof(struct btrfs_root),
 					      GFP_NOFS);
 	int ret;
-	int err = -EIO;
+	int err = -EINVAL;
 	struct btrfs_super_block *disk_super;
-
 	if (!extent_root || !tree_root || !fs_info) {
 		err = -ENOMEM;
 		goto fail;

fs/btrfs/super.c

@@ -236,9 +236,9 @@ static int btrfs_fill_super(struct super_block * sb,
 
 	tree_root = open_ctree(sb, fs_devices);
 
-	if (!tree_root || IS_ERR(tree_root)) {
+	if (IS_ERR(tree_root)) {
 		printk("btrfs: open_ctree failed\n");
-		return -EIO;
+		return PTR_ERR(tree_root);
 	}
 	sb->s_fs_info = tree_root;
 	disk_super = &tree_root->fs_info->super_copy;

fs/btrfs/volumes.c

@@ -237,7 +237,7 @@ int btrfs_scan_one_device(const char *path, int flags, void *holder,
 	if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
 	    sizeof(disk_super->magic))) {
 		printk("no btrfs found on %s\n", path);
-		ret = -ENOENT;
+		ret = -EINVAL;
 		goto error_brelse;
 	}
 	devid = le64_to_cpu(disk_super->dev_item.devid);