> The Linux block layer shares the DISCARD queue limits with SECDISCARD.
> That's different from BLKZEROOUT (QEMU's WRITE_ZEROES). This is a Linux
> implementation detail but I guess virtio-blk can share the DISCARD limits with
> SECDISCARD too...
>
> > @@ -622,6 +628,7 @@ static int virtio_blk_handle_request(VirtIOBlockReq
> *req, MultiReqBuffer *mrb)
> > unsigned out_num = req->elem.out_num;
> > VirtIOBlock *s = req->dev;
> > VirtIODevice *vdev = VIRTIO_DEVICE(s);
> > + bool is_secdiscard = false;
> >
> > if (req->elem.out_num < 1 || req->elem.in_num < 1) {
> > virtio_error(vdev, "virtio-blk missing headers"); @@ -722,6
> > +729,9 @@ static int virtio_blk_handle_request(VirtIOBlockReq *req,
> MultiReqBuffer *mrb)
> > * VIRTIO_BLK_T_OUT flag set. We masked this flag in the switch
> > statement,
> > * so we must mask it for these requests, then we will check if it is
> > set.
> > */
> > + case VIRTIO_BLK_T_SECDISCARD & ~VIRTIO_BLK_T_OUT:
> > + is_secdiscard = true;
> > + __attribute__((fallthrough));
>
> The DISCARD case doesn't use __attribute__((fallthrough)) so this is
> inconsistent.
> QEMU doesn't use __attribute__((fallthrough)) so I suggest dropping this.
Sure, will try to drop the fallthrough case.
>
> > diff --git a/include/standard-headers/linux/virtio_blk.h
> > b/include/standard-headers/linux/virtio_blk.h
> > index 2dcc90826a..c55a07840c 100644
> > --- a/include/standard-headers/linux/virtio_blk.h
> > +++ b/include/standard-headers/linux/virtio_blk.h
> > @@ -40,6 +40,7 @@
> > #define VIRTIO_BLK_F_MQ 12 /* support more than one vq
> */
> > #define VIRTIO_BLK_F_DISCARD 13 /* DISCARD is supported */
> > #define VIRTIO_BLK_F_WRITE_ZEROES 14 /* WRITE ZEROES is
> supported */
> > +#define VIRTIO_BLK_F_SECDISCARD 15 /* WRITE ZEROES is supported
> */
>
> The comment is copy-pasted from WRITE_ZEROES.
Will fix it.
