On 2021/6/30 下午9:30, David Sterba wrote:

On Wed, Jun 30, 2021 at 09:26:20PM +0800, Qu Wenruo wrote:

quoted

quoted

Is there a way to list such subvolumes from progs?

No, root with 0 ref will not show up in "btrfs subv list".

We might need one then, but I'll read the full report, maybe it's a
one-off bug.

quoted

In fact unless we pass @check_ref = false, btrfs_get_fs_root() won't
return such ghost root at all.

In progs the subvolumes are searched directly by the key, so this
(kernel function) is not relevant.

Anyway, you can use the test image from the btrfs-progs patchset to test
btrfs-progs modification.

THanks,
Qu