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Commit 1cde26f9 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Jens Axboe
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virtio_blk: SG_IO passthru support 



Add support for SG_IO passthru to virtio_blk.  We add the scsi command
block after the normal outhdr, and the scsi inhdr with full status
information aswell as the sense buffer before the regular inhdr.

[hch: forward ported, added the VIRTIO_BLK_F_SCSI flags, some comments
 and tested the whole beast]
[axboe: updated to use ->resid and not dual-path the byte count]

Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ checkpatch.pl tweak)
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 6c3b46f7

drivers/block/virtio_blk.c

+50 −14
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ struct virtblk_req 
	struct list_head list;

	struct request *req;

	struct virtio_blk_outhdr out_hdr;

	struct virtio_scsi_inhdr in_hdr;

	u8 status;

};
@@ -49,7 +50,9 @@ static void blk_done(struct virtqueue *vq) 


	spin_lock_irqsave(&vblk->lock, flags);

	while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {

		unsigned int nr_bytes;

		int error;



		switch (vbr->status) {

		case VIRTIO_BLK_S_OK:

			error = 0;
@@ -62,6 +65,12 @@ static void blk_done(struct virtqueue *vq) 
			break;

		}



		if (blk_pc_request(vbr->req)) {

			vbr->req->resid_len = vbr->in_hdr.residual;

			vbr->req->sense_len = vbr->in_hdr.sense_len;

			vbr->req->errors = vbr->in_hdr.errors;

		}



		__blk_end_request_all(vbr->req, error);

		list_del(&vbr->list);

		mempool_free(vbr, vblk->pool);
@@ -74,7 +83,7 @@ static void blk_done(struct virtqueue *vq) 
static bool do_req(struct request_queue *q, struct virtio_blk *vblk,

		   struct request *req)

{

	unsigned long num, out, in;

	unsigned long num, out = 0, in = 0;

	struct virtblk_req *vbr;



	vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
@@ -99,18 +108,36 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 
	if (blk_barrier_rq(vbr->req))

		vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;



	sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));

	num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);

	sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status));

	sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));



	/*

	 * If this is a packet command we need a couple of additional headers.

	 * Behind the normal outhdr we put a segment with the scsi command

	 * block, and before the normal inhdr we put the sense data and the

	 * inhdr with additional status information before the normal inhdr.

	 */

	if (blk_pc_request(vbr->req))

		sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);



	num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);



	if (blk_pc_request(vbr->req)) {

		sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96);

		sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,

			   sizeof(vbr->in_hdr));

	}



	sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,

		   sizeof(vbr->status));



	if (num) {

		if (rq_data_dir(vbr->req) == WRITE) {

			vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;

		out = 1 + num;

		in = 1;

			out += num;

		} else {

			vbr->out_hdr.type |= VIRTIO_BLK_T_IN;

		out = 1;

		in = 1 + num;

			in += num;

		}

	}



	if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
@@ -148,8 +175,16 @@ static void do_virtblk_request(struct request_queue *q) 
static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,

			 unsigned cmd, unsigned long data)

{

	return scsi_cmd_ioctl(bdev->bd_disk->queue,

			      bdev->bd_disk, mode, cmd,

	struct gendisk *disk = bdev->bd_disk;

	struct virtio_blk *vblk = disk->private_data;



	/*

	 * Only allow the generic SCSI ioctls if the host can support it.

	 */

	if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI))

		return -ENOIOCTLCMD;



	return scsi_cmd_ioctl(disk->queue, disk, mode, cmd,

			      (void __user *)data);

}
@@ -356,6 +391,7 @@ static struct virtio_device_id id_table[] = { 
static unsigned int features[] = {

	VIRTIO_BLK_F_BARRIER, 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_SCSI,

};



static struct virtio_driver virtio_blk = {

include/linux/virtio_blk.h

+8 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#define VIRTIO_BLK_F_GEOMETRY	4	/* Legacy geometry available  */

#define VIRTIO_BLK_F_RO		5	/* Disk is read-only */

#define VIRTIO_BLK_F_BLK_SIZE	6	/* Block size of disk is available*/

#define VIRTIO_BLK_F_SCSI	7	/* Supports scsi command passthru */



struct virtio_blk_config

{
@@ -55,6 +56,13 @@ struct virtio_blk_outhdr 
	__u64 sector;

};



struct virtio_scsi_inhdr {

	__u32 errors;

	__u32 data_len;

	__u32 sense_len;

	__u32 residual;

};



/* And this is the final byte of the write scatter-gather list. */

#define VIRTIO_BLK_S_OK		0

#define VIRTIO_BLK_S_IOERR	1