On 2021/8/17 下午9:32, David Sterba wrote:

On Mon, Jun 28, 2021 at 06:26:28PM +0800, Qu Wenruo wrote:

quoted

There is a recent report of ghost subvolumes where such subvolumes has
no ROOT_REF/BACKREF, and 0 root ref.
But without an orphan item, thus kernel won't queue them for cleanup.

Such ghost subvolumes are just here to take up space, and no way to
delete them except by btrfs check, which will try to fix the problem by
adding orphan item.

There is a kernel patch submitted to allow btrfs to detect such ghost
subvolumes and queue them for cleanup.

But btrfs-progs will not continue to call the ioctl if it can't find the
full subvolume path.

Thus this patch will loose the restriction by allowing btrfs-progs to
continue to call the ioctl even if it can't grab the subvolume path.

Signed-off-by: Qu Wenruo <redacted>

Added to devel, thanks. Please send a test case.

That needs kernel support, and I didn't see kernel patch get merged yet.

Thanks,
Qu