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virtio_blk: add discard and write zeroes support

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In commit 88c85538, "virtio-blk: add discard and write zeroes features
to specification" (https://github.com/oasis-tcs/virtio-spec), the virtio
block specification has been extended to add VIRTIO_BLK_T_DISCARD and
VIRTIO_BLK_T_WRITE_ZEROES commands.  This patch enables support for
discard and write zeroes in the virtio-blk driver when the device
advertises the corresponding features, VIRTIO_BLK_F_DISCARD and
VIRTIO_BLK_F_WRITE_ZEROES.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Changpeng Liu 2018-11-01 15:40:35 -07:00 committed by Michael S. Tsirkin
parent c5c08bed84
commit 1f23816b8e
2 changed files with 135 additions and 2 deletions
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83
drivers/block/virtio_blk.c
View File

@ -18,6 +18,7 @@
#define PART_BITS 4
#define VQ_NAME_LEN 16
#define MAX_DISCARD_SEGMENTS 256u
static int major;
static DEFINE_IDA(vd_index_ida);
@ -172,10 +173,48 @@ 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 int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
{
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;
if (unmap)
flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP;
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++;
}
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:
@ -225,6 +264,7 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
int qid = hctx->queue_num;
int err;
bool notify = false;
bool unmap = false;
u32 type;
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
@ -237,6 +277,13 @@ 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_WRITE_ZEROES:
type = VIRTIO_BLK_T_WRITE_ZEROES;
unmap = !(req->cmd_flags & REQ_NOUNMAP);
break;
case REQ_OP_SCSI_IN:
case REQ_OP_SCSI_OUT:
type = VIRTIO_BLK_T_SCSI_CMD;
@ -256,6 +303,12 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
blk_mq_start_request(req);
if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
err = virtblk_setup_discard_write_zeroes(req, unmap);
if (err)
return BLK_STS_RESOURCE;
}
num = blk_rq_map_sg(hctx->queue, req, vbr->sg);
if (num) {
if (rq_data_dir(req) == WRITE)
@ -802,6 +855,32 @@ 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_granularity = blk_size;
virtio_cread(vdev, struct virtio_blk_config,
discard_sector_alignment, &v);
q->limits.discard_alignment = v ? v << SECTOR_SHIFT : 0;
virtio_cread(vdev, struct virtio_blk_config,
max_discard_sectors, &v);
blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
&v);
blk_queue_max_discard_segments(q,
min_not_zero(v,
MAX_DISCARD_SEGMENTS));
blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
}
if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
virtio_cread(vdev, struct virtio_blk_config,
max_write_zeroes_sectors, &v);
blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
}
virtblk_update_capacity(vblk, false);
virtio_device_ready(vdev);
@ -895,14 +974,14 @@ static unsigned int features_legacy[] = {
VIRTIO_BLK_F_SCSI,
#endif
VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
VIRTIO_BLK_F_MQ,
VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
}
;
static unsigned int features[] = {
VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
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_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
};
static struct virtio_driver virtio_blk = {

54
include/uapi/linux/virtio_blk.h
View File

@ -38,6 +38,8 @@
#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
#define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
#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 */
/* Legacy feature bits */
#ifndef VIRTIO_BLK_NO_LEGACY
@ -86,6 +88,39 @@ struct virtio_blk_config {
/* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
__u16 num_queues;
/* the next 3 entries are guarded by VIRTIO_BLK_F_DISCARD */
/*
* The maximum discard sectors (in 512-byte sectors) for
* one segment.
*/
__u32 max_discard_sectors;
/*
* The maximum number of discard segments in a
* discard command.
*/
__u32 max_discard_seg;
/* Discard commands must be aligned to this number of sectors. */
__u32 discard_sector_alignment;
/* the next 3 entries are guarded by VIRTIO_BLK_F_WRITE_ZEROES */
/*
* The maximum number of write zeroes sectors (in 512-byte sectors) in
* one segment.
*/
__u32 max_write_zeroes_sectors;
/*
* The maximum number of segments in a write zeroes
* command.
*/
__u32 max_write_zeroes_seg;
/*
* Set if a VIRTIO_BLK_T_WRITE_ZEROES request may result in the
* deallocation of one or more of the sectors.
*/
__u8 write_zeroes_may_unmap;
__u8 unused1[3];
} __attribute__((packed));
/*
@ -114,6 +149,12 @@ struct virtio_blk_config {
/* Get device ID command */
#define VIRTIO_BLK_T_GET_ID 8
/* Discard command */
#define VIRTIO_BLK_T_DISCARD 11
/* Write zeroes command */
#define VIRTIO_BLK_T_WRITE_ZEROES 13
#ifndef VIRTIO_BLK_NO_LEGACY
/* Barrier before this op. */
#define VIRTIO_BLK_T_BARRIER 0x80000000
@ -133,6 +174,19 @@ struct virtio_blk_outhdr {
__virtio64 sector;
};
/* Unmap this range (only valid for write zeroes command) */
#define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP 0x00000001
/* Discard/write zeroes range for each request. */
struct virtio_blk_discard_write_zeroes {
/* discard/write zeroes start sector */
__le64 sector;
/* number of discard/write zeroes sectors */
__le32 num_sectors;
/* flags for this range */
__le32 flags;
};
#ifndef VIRTIO_BLK_NO_LEGACY
struct virtio_scsi_inhdr {
__virtio32 errors;