Re: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver
On Wed, Jul 05, 2017 at 07:57:07AM +, Liu, Changpeng wrote: > > > > -Original Message- > > From: Paolo Bonzini [mailto:pbonz...@redhat.com] > > Sent: Tuesday, July 4, 2017 5:24 PM > > To: Liu, Changpeng ; virtualization@lists.linux- > > foundation.org > > Cc: stefa...@gmail.com; h...@lst.de; m...@redhat.com > > Subject: Re: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver > > > > > > > > On 05/07/2017 10:44, Changpeng Liu wrote: > > > Currently virtio-blk driver does not provide discard feature flag, so the > > > filesystems which built on top of the block device will not send discard > > > command. This is okay for HDD backend, but it will impact the performance > > > for SSD backend. > > > > > > Add a feature flag VIRTIO_BLK_F_DISCARD and command > > VIRTIO_BLK_T_DISCARD > > > to extend exist virtio-blk protocol, define 16 bytes discard descriptor > > > for each discard segment, the discard segment defination aligns with > > > SCSI or NVM Express protocols, virtio-blk driver will support multi-range > > > discard request as well. > > > > > > Signed-off-by: Changpeng Liu > > > > Please include a patch for the specification. Since we are at it, I > Thanks Paolo, do you mean include a text file which describe the changes for > the specification? Paolo answered that. But please also CC code patch to virtio-comm...@lists.oasis-open.org . This is a subscriber-only list so pls subscribe beforehand: https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio#feedback -- MST ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver
On 05/07/2017 09:57, Liu, Changpeng wrote: >> Please include a patch for the specification. Since we are at it, I > Thanks Paolo, do you mean include a text file which describe the changes for > the specification? The specification is hosted in an svn (Subversion) repository at https://tools.oasis-open.org/version-control/svn/virtio. You can provide a patch and send it to virtio-comm...@lists.oasis-open.org. Thanks, Paolo >> would like to have three operations defined using the same descriptor: >> >> - discard (SCSI UNMAP) >> >> - write zeroes (SCSI WRITE SAME without UNMAP flag) >> >> - write zeroes and possibly discard (SCSI WRITE SAME with UNMAP flag) >> >> The last two can use the same command VIRTIO_BLK_T_WRITE_ZEROES, using >> the reserved field as a flags field. > > Will add write zeroes feature. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
RE: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver
> -Original Message-
> From: Paolo Bonzini [mailto:pbonz...@redhat.com]
> Sent: Tuesday, July 4, 2017 5:24 PM
> To: Liu, Changpeng ; virtualization@lists.linux-
> foundation.org
> Cc: stefa...@gmail.com; h...@lst.de; m...@redhat.com
> Subject: Re: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver
>
>
>
> On 05/07/2017 10:44, Changpeng Liu wrote:
> > Currently virtio-blk driver does not provide discard feature flag, so the
> > filesystems which built on top of the block device will not send discard
> > command. This is okay for HDD backend, but it will impact the performance
> > for SSD backend.
> >
> > Add a feature flag VIRTIO_BLK_F_DISCARD and command
> VIRTIO_BLK_T_DISCARD
> > to extend exist virtio-blk protocol, define 16 bytes discard descriptor
> > for each discard segment, the discard segment defination aligns with
> > SCSI or NVM Express protocols, virtio-blk driver will support multi-range
> > discard request as well.
> >
> > Signed-off-by: Changpeng Liu
>
> Please include a patch for the specification. Since we are at it, I
Thanks Paolo, do you mean include a text file which describe the changes for
the specification?
> would like to have three operations defined using the same descriptor:
>
> - discard (SCSI UNMAP)
>
> - write zeroes (SCSI WRITE SAME without UNMAP flag)
>
> - write zeroes and possibly discard (SCSI WRITE SAME with UNMAP flag)
>
> The last two can use the same command VIRTIO_BLK_T_WRITE_ZEROES, using
> the reserved field as a flags field.
Will add write zeroes feature.
>
> Paolo
>
> > ---
> > drivers/block/virtio_blk.c | 76
> +++--
> > include/uapi/linux/virtio_blk.h | 19 +++
> > 2 files changed, 92 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> > index 0297ad7..8f0c614 100644
> > --- a/drivers/block/virtio_blk.c
> > +++ b/drivers/block/virtio_blk.c
> > @@ -172,10 +172,52 @@ static int virtblk_add_req(struct virtqueue *vq,
> > struct
> virtblk_req *vbr,
> > return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
> > }
> >
> > +static inline int virtblk_setup_discard(struct request *req)
> > +{
> > + unsigned short segments = blk_rq_nr_discard_segments(req), n = 0;
> > + u32 block_size = queue_logical_block_size(req->q);
> > + struct virtio_blk_discard *range;
> > + struct bio *bio;
> > +
> > + if (block_size < 512 || !block_size)
> > + return -1;
> > +
> > + range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
> > + if (!range)
> > + return -1;
> > +
> > + __rq_for_each_bio(bio, req) {
> > + u64 slba = (bio->bi_iter.bi_sector << 9) / block_size;
> > + u32 nlb = bio->bi_iter.bi_size / block_size;
> > +
> > + range[n].reserved = cpu_to_le32(0);
> > + range[n].nlba = cpu_to_le32(nlb);
> > + range[n].slba = cpu_to_le64(slba);
> > + n++;
> > + }
> > +
> > + if (WARN_ON_ONCE(n != segments)) {
> > + kfree(range);
> > + return -1;
> > + }
> > +
> > + req->special_vec.bv_page = virt_to_page(range);
> > + req->special_vec.bv_offset = offset_in_page(range);
> > + req->special_vec.bv_len = sizeof(*range) * segments;
> > + req->rq_flags |= RQF_SPECIAL_PAYLOAD;
> > +
> > + return 0;
> > +}
> > +
> > static inline void virtblk_request_done(struct request *req)
> > {
> > struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
> >
> > + if (req->rq_flags & RQF_SPECIAL_PAYLOAD) {
> > + kfree(page_address(req->special_vec.bv_page) +
> > + req->special_vec.bv_offset);
> > + }
> > +
> > switch (req_op(req)) {
> > case REQ_OP_SCSI_IN:
> > case REQ_OP_SCSI_OUT:
> > @@ -237,6 +279,9 @@ static blk_status_t virtio_queue_rq(struct
> blk_mq_hw_ctx *hctx,
> > case REQ_OP_FLUSH:
> > type = VIRTIO_BLK_T_FLUSH;
> > break;
> > + case REQ_OP_DISCARD:
> > + type = VIRTIO_BLK_T_DISCARD;
> > + break;
> > case REQ_OP_SCSI_IN:
> > case REQ_OP_SCSI_OUT:
> > type = VIRTIO_BLK_T_SCSI_CMD;
> > @@ -256,9 +301,15 @@ static blk_status_t virtio_queue_rq(struct
> blk_mq_hw_ctx *hctx,
> >
> > blk_mq_start_request(req);
> >
> > + if (type == VIR
Re: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver
On Tue, Jul 04, 2017 at 11:24:01AM +0200, Paolo Bonzini wrote: > > > On 05/07/2017 10:44, Changpeng Liu wrote: > > Currently virtio-blk driver does not provide discard feature flag, so the > > filesystems which built on top of the block device will not send discard > > command. This is okay for HDD backend, but it will impact the performance > > for SSD backend. > > > > Add a feature flag VIRTIO_BLK_F_DISCARD and command VIRTIO_BLK_T_DISCARD > > to extend exist virtio-blk protocol, define 16 bytes discard descriptor > > for each discard segment, the discard segment defination aligns with > > SCSI or NVM Express protocols, virtio-blk driver will support multi-range > > discard request as well. > > > > Signed-off-by: Changpeng Liu > > Please include a patch for the specification. Most importantly, please remember to copy virtio-...@lists.oasis-open.org on anything that changes the host/guest interface. > Since we are at it, I > would like to have three operations defined using the same descriptor: > > - discard (SCSI UNMAP) > > - write zeroes (SCSI WRITE SAME without UNMAP flag) > > - write zeroes and possibly discard (SCSI WRITE SAME with UNMAP flag) > > The last two can use the same command VIRTIO_BLK_T_WRITE_ZEROES, using > the reserved field as a flags field. > > Paolo > > --- > > drivers/block/virtio_blk.c | 76 > > +++-- > > include/uapi/linux/virtio_blk.h | 19 +++ > > 2 files changed, 92 insertions(+), 3 deletions(-) ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v2] virtio-blk: add DISCARD support to virtio-blk driver
On 05/07/2017 10:44, Changpeng Liu wrote:
> Currently virtio-blk driver does not provide discard feature flag, so the
> filesystems which built on top of the block device will not send discard
> command. This is okay for HDD backend, but it will impact the performance
> for SSD backend.
>
> Add a feature flag VIRTIO_BLK_F_DISCARD and command VIRTIO_BLK_T_DISCARD
> to extend exist virtio-blk protocol, define 16 bytes discard descriptor
> for each discard segment, the discard segment defination aligns with
> SCSI or NVM Express protocols, virtio-blk driver will support multi-range
> discard request as well.
>
> Signed-off-by: Changpeng Liu
Please include a patch for the specification. Since we are at it, I
would like to have three operations defined using the same descriptor:
- discard (SCSI UNMAP)
- write zeroes (SCSI WRITE SAME without UNMAP flag)
- write zeroes and possibly discard (SCSI WRITE SAME with UNMAP flag)
The last two can use the same command VIRTIO_BLK_T_WRITE_ZEROES, using
the reserved field as a flags field.
Paolo
> ---
> drivers/block/virtio_blk.c | 76
> +++--
> include/uapi/linux/virtio_blk.h | 19 +++
> 2 files changed, 92 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 0297ad7..8f0c614 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -172,10 +172,52 @@ static int virtblk_add_req(struct virtqueue *vq, struct
> virtblk_req *vbr,
> return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
> }
>
> +static inline int virtblk_setup_discard(struct request *req)
> +{
> + unsigned short segments = blk_rq_nr_discard_segments(req), n = 0;
> + u32 block_size = queue_logical_block_size(req->q);
> + struct virtio_blk_discard *range;
> + struct bio *bio;
> +
> + if (block_size < 512 || !block_size)
> + return -1;
> +
> + range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
> + if (!range)
> + return -1;
> +
> + __rq_for_each_bio(bio, req) {
> + u64 slba = (bio->bi_iter.bi_sector << 9) / block_size;
> + u32 nlb = bio->bi_iter.bi_size / block_size;
> +
> + range[n].reserved = cpu_to_le32(0);
> + range[n].nlba = cpu_to_le32(nlb);
> + range[n].slba = cpu_to_le64(slba);
> + n++;
> + }
> +
> + if (WARN_ON_ONCE(n != segments)) {
> + kfree(range);
> + return -1;
> + }
> +
> + req->special_vec.bv_page = virt_to_page(range);
> + req->special_vec.bv_offset = offset_in_page(range);
> + req->special_vec.bv_len = sizeof(*range) * segments;
> + req->rq_flags |= RQF_SPECIAL_PAYLOAD;
> +
> + return 0;
> +}
> +
> static inline void virtblk_request_done(struct request *req)
> {
> struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
>
> + if (req->rq_flags & RQF_SPECIAL_PAYLOAD) {
> + kfree(page_address(req->special_vec.bv_page) +
> + req->special_vec.bv_offset);
> + }
> +
> switch (req_op(req)) {
> case REQ_OP_SCSI_IN:
> case REQ_OP_SCSI_OUT:
> @@ -237,6 +279,9 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx
> *hctx,
> case REQ_OP_FLUSH:
> type = VIRTIO_BLK_T_FLUSH;
> break;
> + case REQ_OP_DISCARD:
> + type = VIRTIO_BLK_T_DISCARD;
> + break;
> case REQ_OP_SCSI_IN:
> case REQ_OP_SCSI_OUT:
> type = VIRTIO_BLK_T_SCSI_CMD;
> @@ -256,9 +301,15 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx
> *hctx,
>
> blk_mq_start_request(req);
>
> + if (type == VIRTIO_BLK_T_DISCARD) {
> + err = virtblk_setup_discard(req);
> + if (err)
> + return BLK_STS_IOERR;
> + }
> +
> num = blk_rq_map_sg(hctx->queue, req, vbr->sg);
> if (num) {
> - if (rq_data_dir(req) == WRITE)
> + if (rq_data_dir(req) == WRITE || type == VIRTIO_BLK_T_DISCARD)
> vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev,
> VIRTIO_BLK_T_OUT);
> else
> vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev,
> VIRTIO_BLK_T_IN);
> @@ -767,6 +818,25 @@ static int virtblk_probe(struct virtio_device *vdev)
> if (!err && opt_io_size)
> blk_queue_io_opt(q, blk_size * opt_io_size);
>
> + if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
> + q->limits.discard_alignment = blk_size;
> + q->limits.discard_granularity = blk_size;
> +
> + virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
> &v);
> + if (v)
> + blk_queue_max_discard_sectors(q, v);
> + else
> + blk_queue_max_discard_sectors(q, -1U);
> +
> + virtio_cread(vdev, struct virtio_blk_config, max_d
