btrfs: hold a ref on the root in btrfs_ioctl_get_subvol_info

We look up whatever root userspace has given us, we need to hold a ref
throughout this operation.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 2eb5a5dc07bd73b97867143344aa8bb79e1a804c..2797a1249f25da8fce487191725fef7fdc50292b 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2683,6 +2683,10 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
        root = btrfs_get_fs_root(fs_info, &key, true);
        if (IS_ERR(root)) {
                ret = PTR_ERR(root);
+               goto out_free;
+       }
+       if (!btrfs_grab_fs_root(root)) {
+               ret = -ENOENT;
                goto out;
        }
        root_item = &root->root_item;
@@ -2760,6 +2764,8 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
                ret = -EFAULT;
 
 out:
+       btrfs_put_fs_root(root);
+out_free:
        btrfs_free_path(path);
        kzfree(subvol_info);
        return ret;