path: root/drivers/block/virtio_blk.c

//#define DEBUG
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/virtio.h>
#include <linux/virtio_blk.h>
#include <linux/scatterlist.h>
#include <linux/string_helpers.h>
#include <scsi/scsi_cmnd.h>
#include <linux/idr.h>

#define PART_BITS 4

static bool use_bio;
module_param(use_bio, bool, S_IRUGO);

static int major;
static DEFINE_IDA(vd_index_ida);

struct workqueue_struct *virtblk_wq;

struct virtio_blk
{
	struct virtio_device *vdev;
	struct virtqueue *vq;
	wait_queue_head_t queue_wait;

	/* The disk structure for the kernel. */
	struct gendisk *disk;

	mempool_t *pool;

	/* Process context for config space updates */
	struct work_struct config_work;

	/* Lock for config space updates */
	struct mutex config_lock;

	/* enable config space updates */
	bool config_enable;

	/* What host tells us, plus 2 for header & tailer. */
	unsigned int sg_elems;

	/* Ida index - used to track minor number allocations. */
	int index;

	/* Scatterlist: can be too big for stack. */
	struct scatterlist sg[/*sg_elems*/];
};

struct virtblk_req
{
	struct request *req;
	struct bio *bio;
	struct virtio_blk_outhdr out_hdr;
	struct virtio_scsi_inhdr in_hdr;
	struct work_struct work;
	struct virtio_blk *vblk;
	int flags;
	u8 status;
	struct scatterlist sg[];
};

enum {
	VBLK_IS_FLUSH		= 1,
	VBLK_REQ_FLUSH		= 2,
	VBLK_REQ_DATA		= 4,
	VBLK_REQ_FUA		= 8,
};

static inline int virtblk_result(struct virtblk_req *vbr)
{
	switch (vbr->status) {
	case VIRTIO_BLK_S_OK:
		return 0;
	case VIRTIO_BLK_S_UNSUPP:
		return -ENOTTY;
	default:
		return -EIO;
	}
}

static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
						    gfp_t gfp_mask)
{
	struct virtblk_req *vbr;

	vbr = mempool_alloc(vblk->pool, gfp_mask);
	if (!vbr)
		return NULL;

	vbr->vblk = vblk;
	if (use_bio)
		sg_init_table(vbr->sg, vblk->sg_elems);

	return vbr;
}

static int __virtblk_add_req(struct virtqueue *vq,
			     struct virtblk_req *vbr,
			     struct scatterlist *data_sg,
			     bool have_data)
{
	struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
	unsigned int num_out = 0, num_in = 0;
	int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;

	sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
	sgs[num_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.
	 */
	if (type == VIRTIO_BLK_T_SCSI_CMD) {
		sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
		sgs[num_out++] = &cmd;
	}

	if (have_data) {
		if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
			sgs[num_out++] = data_sg;
		else
			sgs[num_out + num_in++] = data_sg;
	}

	if (type == VIRTIO_BLK_T_SCSI_CMD) {
		sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
		sgs[num_out + num_in++] = &sense;
		sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
		sgs[num_out + num_in++] = &inhdr;
	}

	sg_init_one(&status, &vbr->status, sizeof(vbr->status));
	sgs[num_out + num_in++] = &status;

	return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
}

static void virtblk_add_req(struct virtblk_req *vbr, bool have_data)
{
	struct virtio_blk *vblk = vbr->vblk;
	DEFINE_WAIT(wait);
	int ret;

	spin_lock_irq(vblk->disk->