btrfs: hold a ref on the root in create_subvol

We're creating the new root here, but we should hold the ref until after
we've initialized the inode for it.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 5342e4a..0e524f3 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -672,10 +672,16 @@ static noinline int create_subvol(struct inode *dir,
                btrfs_abort_transaction(trans, ret);
                goto fail;
        }
+       if (!btrfs_grab_fs_root(new_root)) {
+               ret = -ENOENT;
+               btrfs_abort_transaction(trans, ret);
+               goto fail;
+       }
 
        btrfs_record_root_in_trans(trans, new_root);
 
        ret = btrfs_create_subvol_root(trans, new_root, root, new_dirid);
+       btrfs_put_fs_root(new_root);
        if (ret) {
                /* We potentially lose an unused inode item here */
                btrfs_abort_transaction(trans, ret);