[PATCH RFC 3/8] virtio_blk: Add support for provision requests

Sarthak Kukreti
2022-09-15T16:49:02Z

From: Sarthak Kukreti <sarthakkukreti@chromium.org>

Adds support for provision requests. Provision requests act like
the inverse of discards.

Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
---
drivers/block/virtio_blk.c | 48 +++++++++++++++++++++++++++++++++
include/uapi/linux/virtio_blk.h | 9 +++++++
2 files changed, 57 insertions(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 30255fcaf181..eacc2bffe1d1 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -178,6 +178,39 @@ static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
return 0;
}

+static int virtblk_setup_provision(struct request *req)
+{
+ unsigned short segments = blk_rq_nr_discard_segments(req);
+ unsigned short n = 0;
+
+ struct virtio_blk_discard_write_zeroes *range;
+ struct bio *bio;
+ u32 flags = 0;
+
+ range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
+ if (!range)
+ return -ENOMEM;
+
+ __rq_for_each_bio(bio, req) {
+ u64 sector = bio->bi_iter.bi_sector;
+ u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
+
+ range[n].flags = cpu_to_le32(flags);
+ range[n].num_sectors = cpu_to_le32(num_sectors);
+ range[n].sector = cpu_to_le64(sector);
+ n++;
+ }
+
+ WARN_ON_ONCE(n != segments);
+
+ 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 void virtblk_unmap_data(struct request *req, struct virtblk_req *vbr)
{
if (blk_rq_nr_phys_segments(req))
@@ -243,6 +276,9 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
case REQ_OP_DRV_IN:
type = VIRTIO_BLK_T_GET_ID;
break;
+ case REQ_OP_PROVISION:
+ type = VIRTIO_BLK_T_PROVISION;
+ break;
default:
WARN_ON_ONCE(1);
return BLK_STS_IOERR;
@@ -256,6 +292,11 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
return BLK_STS_RESOURCE;
}

+ if (type == VIRTIO_BLK_T_PROVISION) {
+ if (virtblk_setup_provision(req))
+ return BLK_STS_RESOURCE;
+ }
+
return 0;
}

@@ -1075,6 +1116,12 @@ static int virtblk_probe(struct virtio_device *vdev)
blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
}

+ if (virtio_has_feature(vdev, VIRTIO_BLK_F_PROVISION)) {
+ virtio_cread(vdev, struct virtio_blk_config,
+ max_provision_sectors, &v);
+ q->limits.max_provision_sectors = v ? v : UINT_MAX;
+ }
+
virtblk_update_capacity(vblk, false);
virtio_device_ready(vdev);

@@ -1177,6 +1224,7 @@ static unsigned int features[] = {
VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
+ VIRTIO_BLK_F_PROVISION,
};

static struct virtio_driver virtio_blk = {
diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
index d888f013d9ff..184f8cf6d185 100644
--- a/include/uapi/linux/virtio_blk.h
+++ b/include/uapi/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_PROVISION 15 /* provision is supported */

/* Legacy feature bits */
#ifndef VIRTIO_BLK_NO_LEGACY
@@ -120,6 +121,11 @@ struct virtio_blk_config {
*/
__u8 write_zeroes_may_unmap;

+ /*
+ * The maximum number of sectors in a provision request.
+ */
+ __virtio32 max_provision_sectors;
+
__u8 unused1[3];
} __attribute__((packed));

@@ -155,6 +161,9 @@ struct virtio_blk_config {
/* Write zeroes command */
#define VIRTIO_BLK_T_WRITE_ZEROES 13

+/* Provision command */
+#define VIRTIO_BLK_T_PROVISION 14
+
#ifndef VIRTIO_BLK_NO_LEGACY
/* Barrier before this op. */
#define VIRTIO_BLK_T_BARRIER 0x80000000
--
2.31.0