Re: [PATCH v2 1/1] dm-integrity: replace forgeable discard filler with a keyed sector marker

[Milan Broz <gmazyland@gmail.com>]

On 7/30/26 5:29 PM, Mikulas Patocka wrote:
> Hi
> 
> I accepted the patch (and made some small modifications to it).

Mikulas, you added this part to constructor:

+	if (!!(ic->sb->flags & cpu_to_le32(SB_FLAG_DISCARD_KEYED)) != ic->discard_keyed) {
+		r = -EINVAL;
+		ti->error = "Mismatch in the discard_keyed flag";
+		goto bad;
+	}

Unfortunately, this is not going to work.

In integritysetup, allowing discard is an active flag, not a format flag.
It should be ok to activate discard later, but this check blocks it.
It should also allow to activate the device without discard (even if it
was activated before with it).

IMO, it should upgrade the superblock if allow_discards_keyed is set
on activation (and then do not allow it to revert back).

With the current approach, I cannot add this option to integritysetup.
We just have no way to send allow_discard in format action (as it is
an activation flag only in our API).

Milan