From: Boris Burkov <boris@bur.io>
Date: Thu, 11 Jan 2024 01:51:26 +0000 (-0800)
Subject: btrfs: forbid creating subvol qgroups
X-Git-Tag: v6.7.6~305
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1429a6d1312877b54768edba19e33b1dfa5277d9;p=thirdparty%2Fkernel%2Fstable.git

btrfs: forbid creating subvol qgroups

commit 0c309d66dacddf8ce939b891d9ead4a8e21ad6f0 upstream.

Creating a qgroup 0/subvolid leads to various races and it isn't
helpful, because you can't specify a subvol id when creating a subvol,
so you can't be sure it will be the right one. Any requirements on the
automatic subvol can be gratified by using a higher level qgroup and the
inheritance parameters of subvol creation.

Fixes: cecbb533b5fc ("btrfs: record simple quota deltas in delayed refs")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 69e91341fd637..0bd43b863c43a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3815,6 +3815,11 @@ static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
 		goto out;
 	}
 
+	if (sa->create && is_fstree(sa->qgroupid)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	trans = btrfs_join_transaction(root);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);