scsi_tgt_lib.c

linux 内核源代码

{
	struct Scsi_Host *shost = scsi_tgt_cmd_to_host(cmd);
	int err;

	dprintk("cmd %p %lu\n", cmd, rq_data_dir(cmd->request));

	err = shost->hostt->transfer_response(cmd, scsi_tgt_cmd_done);
	switch (err) {
	case SCSI_MLQUEUE_HOST_BUSY:
	case SCSI_MLQUEUE_DEVICE_BUSY:
		return -EAGAIN;
	}
	return 0;
}

static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
{
	struct request *rq = cmd->request;
	int count;

	cmd->use_sg = rq->nr_phys_segments;
	cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);
	if (!cmd->request_buffer)
		return -ENOMEM;

	cmd->request_bufflen = rq->data_len;

	dprintk("cmd %p cnt %d %lu\n", cmd, cmd->use_sg, rq_data_dir(rq));
	count = blk_rq_map_sg(rq->q, rq, cmd->request_buffer);
	if (likely(count <= cmd->use_sg)) {
		cmd->use_sg = count;
		return 0;
	}

	eprintk("cmd %p cnt %d\n", cmd, cmd->use_sg);
	scsi_free_sgtable(cmd);
	return -EINVAL;
}

/* TODO: test this crap and replace bio_map_user with new interface maybe */
static int scsi_map_user_pages(struct scsi_tgt_cmd *tcmd, struct scsi_cmnd *cmd,
			       unsigned long uaddr, unsigned int len, int rw)
{
	struct request_queue *q = cmd->request->q;
	struct request *rq = cmd->request;
	int err;

	dprintk("%lx %u\n", uaddr, len);
	err = blk_rq_map_user(q, rq, (void *)uaddr, len);
	if (err) {
		/*
		 * TODO: need to fixup sg_tablesize, max_segment_size,
		 * max_sectors, etc for modern HW and software drivers
		 * where this value is bogus.
		 *
		 * TODO2: we can alloc a reserve buffer of max size
		 * we can handle and do the slow copy path for really large
		 * IO.
		 */
		eprintk("Could not handle request of size %u.\n", len);
		return err;
	}

	tcmd->bio = rq->bio;
	err = scsi_tgt_init_cmd(cmd, GFP_KERNEL);
	if (err)
		goto unmap_rq;

	return 0;

unmap_rq:
	scsi_unmap_user_pages(tcmd);
	return err;
}

static int scsi_tgt_copy_sense(struct scsi_cmnd *cmd, unsigned long uaddr,
				unsigned len)
{
	char __user *p = (char __user *) uaddr;

	if (copy_from_user(cmd->sense_buffer, p,
			   min_t(unsigned, SCSI_SENSE_BUFFERSIZE, len))) {
		printk(KERN_ERR "Could not copy the sense buffer\n");
		return -EIO;
	}
	return 0;
}

static int scsi_tgt_abort_cmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
{
	struct scsi_tgt_cmd *tcmd;
	int err;

	err = shost->hostt->eh_abort_handler(cmd);
	if (err)
		eprintk("fail to abort %p\n", cmd);

	tcmd = cmd->request->end_io_data;
	scsi_tgt_cmd_destroy(&tcmd->work);
	return err;
}

static struct request *tgt_cmd_hash_lookup(struct request_queue *q, u64 tag)
{
	struct scsi_tgt_queuedata *qdata = q->queuedata;
	struct request *rq = NULL;
	struct list_head *head;
	struct scsi_tgt_cmd *tcmd;
	unsigned long flags;

	head = &qdata->cmd_hash[cmd_hashfn(tag)];
	spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
	list_for_each_entry(tcmd, head, hash_list) {
		if (tcmd->tag == tag) {
			rq = tcmd->rq;
			list_del(&tcmd->hash_list);
			break;
		}
	}
	spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);

	return rq;
}

int scsi_tgt_kspace_exec(int host_no, u64 itn_id, int result, u64 tag,
			 unsigned long uaddr, u32 len, unsigned long sense_uaddr,
			 u32 sense_len, u8 rw)
{
	struct Scsi_Host *shost;
	struct scsi_cmnd *cmd;
	struct request *rq;
	struct scsi_tgt_cmd *tcmd;
	int err = 0;

	dprintk("%d %llu %d %u %lx %u\n", host_no, (unsigned long long) tag,
		result, len, uaddr, rw);

	/* TODO: replace with a O(1) alg */
	shost = scsi_host_lookup(host_no);
	if (IS_ERR(shost)) {
		printk(KERN_ERR "Could not find host no %d\n", host_no);
		return -EINVAL;
	}

	if (!shost->uspace_req_q) {
		printk(KERN_ERR "Not target scsi host %d\n", host_no);
		goto done;
	}

	rq = tgt_cmd_hash_lookup(shost->uspace_req_q, tag);
	if (!rq) {
		printk(KERN_ERR "Could not find tag %llu\n",
		       (unsigned long long) tag);
		err = -EINVAL;
		goto done;
	}
	cmd = rq->special;

	dprintk("cmd %p scb %x result %d len %d bufflen %u %lu %x\n",
		cmd, cmd->cmnd[0], result, len, cmd->request_bufflen,
		rq_data_dir(rq), cmd->cmnd[0]);

	if (result == TASK_ABORTED) {
		scsi_tgt_abort_cmd(shost, cmd);
		goto done;
	}
	/*
	 * store the userspace values here, the working values are
	 * in the request_* values
	 */
	tcmd = cmd->request->end_io_data;
	cmd->result = result;

	if (cmd->result == SAM_STAT_CHECK_CONDITION)
		scsi_tgt_copy_sense(cmd, sense_uaddr, sense_len);

	if (len) {
		err = scsi_map_user_pages(rq->end_io_data, cmd, uaddr, len, rw);
		if (err) {
			/*
			 * user-space daemon bugs or OOM
			 * TODO: we can do better for OOM.
			 */
			struct scsi_tgt_queuedata *qdata;
			struct list_head *head;
			unsigned long flags;

			eprintk("cmd %p ret %d uaddr %lx len %d rw %d\n",
				cmd, err, uaddr, len, rw);

			qdata = shost->uspace_req_q->queuedata;
			head = &qdata->cmd_hash[cmd_hashfn(tcmd->tag)];

			spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
			list_add(&tcmd->hash_list, head);
			spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);

			goto done;
		}
	}
	err = scsi_tgt_transfer_response(cmd);
done:
	scsi_host_put(shost);
	return err;
}

int scsi_tgt_tsk_mgmt_request(struct Scsi_Host *shost, u64 itn_id,
			      int function, u64 tag, struct scsi_lun *scsilun,
			      void *data)
{
	int err;

	/* TODO: need to retry if this fails. */
	err = scsi_tgt_uspace_send_tsk_mgmt(shost->host_no, itn_id,
					    function, tag, scsilun, data);
	if (err < 0)
		eprintk("The task management request lost!\n");
	return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_tsk_mgmt_request);

int scsi_tgt_kspace_tsk_mgmt(int host_no, u64 itn_id, u64 mid, int result)
{
	struct Scsi_Host *shost;
	int err = -EINVAL;

	dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);

	shost = scsi_host_lookup(host_no);
	if (IS_ERR(shost)) {
		printk(KERN_ERR "Could not find host no %d\n", host_no);
		return err;
	}

	if (!shost->uspace_req_q) {
		printk(KERN_ERR "Not target scsi host %d\n", host_no);
		goto done;
	}

	err = shost->transportt->tsk_mgmt_response(shost, itn_id, mid, result);
done:
	scsi_host_put(shost);
	return err;
}

int scsi_tgt_it_nexus_create(struct Scsi_Host *shost, u64 itn_id,
			     char *initiator)
{
	int err;

	/* TODO: need to retry if this fails. */
	err = scsi_tgt_uspace_send_it_nexus_request(shost->host_no, itn_id, 0,
						    initiator);
	if (err < 0)
		eprintk("The i_t_neuxs request lost, %d %llx!\n",
			shost->host_no, (unsigned long long)itn_id);
	return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_it_nexus_create);

int scsi_tgt_it_nexus_destroy(struct Scsi_Host *shost, u64 itn_id)
{
	int err;

	/* TODO: need to retry if this fails. */
	err = scsi_tgt_uspace_send_it_nexus_request(shost->host_no,
						    itn_id, 1, NULL);
	if (err < 0)
		eprintk("The i_t_neuxs request lost, %d %llx!\n",
			shost->host_no, (unsigned long long)itn_id);
	return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_it_nexus_destroy);

int scsi_tgt_kspace_it_nexus_rsp(int host_no, u64 itn_id, int result)
{
	struct Scsi_Host *shost;
	int err = -EINVAL;

	dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);

	shost = scsi_host_lookup(host_no);
	if (IS_ERR(shost)) {
		printk(KERN_ERR "Could not find host no %d\n", host_no);
		return err;
	}

	if (!shost->uspace_req_q) {
		printk(KERN_ERR "Not target scsi host %d\n", host_no);
		goto done;
	}

	err = shost->transportt->it_nexus_response(shost, itn_id, result);
done:
	scsi_host_put(shost);
	return err;
}

static int __init scsi_tgt_init(void)
{
	int err;

	scsi_tgt_cmd_cache = kmem_cache_create("scsi_tgt_cmd",
					       sizeof(struct scsi_tgt_cmd),
					       0, 0, NULL);
	if (!scsi_tgt_cmd_cache)
		return -ENOMEM;

	scsi_tgtd = create_workqueue("scsi_tgtd");
	if (!scsi_tgtd) {
		err = -ENOMEM;
		goto free_kmemcache;
	}

	err = scsi_tgt_if_init();
	if (err)
		goto destroy_wq;

	return 0;

destroy_wq:
	destroy_workqueue(scsi_tgtd);
free_kmemcache:
	kmem_cache_destroy(scsi_tgt_cmd_cache);
	return err;
}

static void __exit scsi_tgt_exit(void)
{
	destroy_workqueue(scsi_tgtd);
	scsi_tgt_if_exit();
	kmem_cache_destroy(scsi_tgt_cmd_cache);
}

module_init(scsi_tgt_init);
module_exit(scsi_tgt_exit);

MODULE_DESCRIPTION("SCSI target core");
MODULE_LICENSE("GPL");