scsi_tgt_lib.c

linux 内核源代码

/*
 * SCSI target lib functions
 *
 * Copyright (C) 2005 Mike Christie <[e-mail]>
 * Copyright (C) 2005 FUJITA Tomonori <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */
#include <linux/blkdev.h>
#include <linux/hash.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_tgt.h>

#include "scsi_tgt_priv.h"

static struct workqueue_struct *scsi_tgtd;
static struct kmem_cache *scsi_tgt_cmd_cache;

/*
 * TODO: this struct will be killed when the block layer supports large bios
 * and James's work struct code is in
 */
struct scsi_tgt_cmd {
	/* TODO replace work with James b's code */
	struct work_struct work;
	/* TODO fix limits of some drivers */
	struct bio *bio;

	struct list_head hash_list;
	struct request *rq;
	u64 itn_id;
	u64 tag;
};

#define TGT_HASH_ORDER	4
#define cmd_hashfn(tag)	hash_long((unsigned long) (tag), TGT_HASH_ORDER)

struct scsi_tgt_queuedata {
	struct Scsi_Host *shost;
	struct list_head cmd_hash[1 << TGT_HASH_ORDER];
	spinlock_t cmd_hash_lock;
};

/*
 * Function:	scsi_host_get_command()
 *
 * Purpose:	Allocate and setup a scsi command block and blk request
 *
 * Arguments:	shost	- scsi host
 *		data_dir - dma data dir
 *		gfp_mask- allocator flags
 *
 * Returns:	The allocated scsi command structure.
 *
 * This should be called by target LLDs to get a command.
 */
struct scsi_cmnd *scsi_host_get_command(struct Scsi_Host *shost,
					enum dma_data_direction data_dir,
					gfp_t gfp_mask)
{
	int write = (data_dir == DMA_TO_DEVICE);
	struct request *rq;
	struct scsi_cmnd *cmd;
	struct scsi_tgt_cmd *tcmd;

	/* Bail if we can't get a reference to the device */
	if (!get_device(&shost->shost_gendev))
		return NULL;

	tcmd = kmem_cache_alloc(scsi_tgt_cmd_cache, GFP_ATOMIC);
	if (!tcmd)
		goto put_dev;

	/*
	 * The blk helpers are used to the READ/WRITE requests
	 * transfering data from a initiator point of view. Since
	 * we are in target mode we want the opposite.
	 */
	rq = blk_get_request(shost->uspace_req_q, !write, gfp_mask);
	if (!rq)
		goto free_tcmd;

	cmd = __scsi_get_command(shost, gfp_mask);
	if (!cmd)
		goto release_rq;

	memset(cmd, 0, sizeof(*cmd));
	cmd->sc_data_direction = data_dir;
	cmd->jiffies_at_alloc = jiffies;
	cmd->request = rq;

	rq->special = cmd;
	rq->cmd_type = REQ_TYPE_SPECIAL;
	rq->cmd_flags |= REQ_TYPE_BLOCK_PC;
	rq->end_io_data = tcmd;

	tcmd->rq = rq;

	return cmd;

release_rq:
	blk_put_request(rq);
free_tcmd:
	kmem_cache_free(scsi_tgt_cmd_cache, tcmd);
put_dev:
	put_device(&shost->shost_gendev);
	return NULL;

}
EXPORT_SYMBOL_GPL(scsi_host_get_command);

/*
 * Function:	scsi_host_put_command()
 *
 * Purpose:	Free a scsi command block
 *
 * Arguments:	shost	- scsi host
 * 		cmd	- command block to free
 *
 * Returns:	Nothing.
 *
 * Notes:	The command must not belong to any lists.
 */
void scsi_host_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
{
	struct request_queue *q = shost->uspace_req_q;
	struct request *rq = cmd->request;
	struct scsi_tgt_cmd *tcmd = rq->end_io_data;
	unsigned long flags;

	kmem_cache_free(scsi_tgt_cmd_cache, tcmd);

	spin_lock_irqsave(q->queue_lock, flags);
	__blk_put_request(q, rq);
	spin_unlock_irqrestore(q->queue_lock, flags);

	__scsi_put_command(shost, cmd, &shost->shost_gendev);
}
EXPORT_SYMBOL_GPL(scsi_host_put_command);

static void cmd_hashlist_del(struct scsi_cmnd *cmd)
{
	struct request_queue *q = cmd->request->q;
	struct scsi_tgt_queuedata *qdata = q->queuedata;
	unsigned long flags;
	struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;

	spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
	list_del(&tcmd->hash_list);
	spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
}

static void scsi_unmap_user_pages(struct scsi_tgt_cmd *tcmd)
{
	blk_rq_unmap_user(tcmd->bio);
}

static void scsi_tgt_cmd_destroy(struct work_struct *work)
{
	struct scsi_tgt_cmd *tcmd =
		container_of(work, struct scsi_tgt_cmd, work);
	struct scsi_cmnd *cmd = tcmd->rq->special;

	dprintk("cmd %p %d %lu\n", cmd, cmd->sc_data_direction,
		rq_data_dir(cmd->request));
	scsi_unmap_user_pages(tcmd);
	scsi_host_put_command(scsi_tgt_cmd_to_host(cmd), cmd);
}

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

	tcmd->itn_id = itn_id;
	tcmd->tag = tag;
	tcmd->bio = NULL;
	INIT_WORK(&tcmd->work, scsi_tgt_cmd_destroy);
	spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
	head = &qdata->cmd_hash[cmd_hashfn(tag)];
	list_add(&tcmd->hash_list, head);
	spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
}

/*
 * scsi_tgt_alloc_queue - setup queue used for message passing
 * shost: scsi host
 *
 * This should be called by the LLD after host allocation.
 * And will be released when the host is released.
 */
int scsi_tgt_alloc_queue(struct Scsi_Host *shost)
{
	struct scsi_tgt_queuedata *queuedata;
	struct request_queue *q;
	int err, i;

	/*
	 * Do we need to send a netlink event or should uspace
	 * just respond to the hotplug event?
	 */
	q = __scsi_alloc_queue(shost, NULL);
	if (!q)
		return -ENOMEM;

	queuedata = kzalloc(sizeof(*queuedata), GFP_KERNEL);
	if (!queuedata) {
		err = -ENOMEM;
		goto cleanup_queue;
	}
	queuedata->shost = shost;
	q->queuedata = queuedata;

	/*
	 * this is a silly hack. We should probably just queue as many
	 * command as is recvd to userspace. uspace can then make
	 * sure we do not overload the HBA
	 */
	q->nr_requests = shost->can_queue;
	/*
	 * We currently only support software LLDs so this does
	 * not matter for now. Do we need this for the cards we support?
	 * If so we should make it a host template value.
	 */
	blk_queue_dma_alignment(q, 0);
	shost->uspace_req_q = q;

	for (i = 0; i < ARRAY_SIZE(queuedata->cmd_hash); i++)
		INIT_LIST_HEAD(&queuedata->cmd_hash[i]);
	spin_lock_init(&queuedata->cmd_hash_lock);

	return 0;

cleanup_queue:
	blk_cleanup_queue(q);
	return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_alloc_queue);

void scsi_tgt_free_queue(struct Scsi_Host *shost)
{
	int i;
	unsigned long flags;
	struct request_queue *q = shost->uspace_req_q;
	struct scsi_cmnd *cmd;
	struct scsi_tgt_queuedata *qdata = q->queuedata;
	struct scsi_tgt_cmd *tcmd, *n;
	LIST_HEAD(cmds);

	spin_lock_irqsave(&qdata->cmd_hash_lock, flags);

	for (i = 0; i < ARRAY_SIZE(qdata->cmd_hash); i++) {
		list_for_each_entry_safe(tcmd, n, &qdata->cmd_hash[i],
					 hash_list) {
			list_del(&tcmd->hash_list);
			list_add(&tcmd->hash_list, &cmds);
		}
	}

	spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);

	while (!list_empty(&cmds)) {
		tcmd = list_entry(cmds.next, struct scsi_tgt_cmd, hash_list);
		list_del(&tcmd->hash_list);
		cmd = tcmd->rq->special;

		shost->hostt->eh_abort_handler(cmd);
		scsi_tgt_cmd_destroy(&tcmd->work);
	}
}
EXPORT_SYMBOL_GPL(scsi_tgt_free_queue);

struct Scsi_Host *scsi_tgt_cmd_to_host(struct scsi_cmnd *cmd)
{
	struct scsi_tgt_queuedata *queue = cmd->request->q->queuedata;
	return queue->shost;
}
EXPORT_SYMBOL_GPL(scsi_tgt_cmd_to_host);

/*
 * scsi_tgt_queue_command - queue command for userspace processing
 * @cmd:	scsi command
 * @scsilun:	scsi lun
 * @tag:	unique value to identify this command for tmf
 */
int scsi_tgt_queue_command(struct scsi_cmnd *cmd, u64 itn_id,
			   struct scsi_lun *scsilun, u64 tag)
{
	struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
	int err;

	init_scsi_tgt_cmd(cmd->request, tcmd, itn_id, tag);
	err = scsi_tgt_uspace_send_cmd(cmd, itn_id, scsilun, tag);
	if (err)
		cmd_hashlist_del(cmd);

	return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_queue_command);

/*
 * This is run from a interrpt handler normally and the unmap
 * needs process context so we must queue
 */
static void scsi_tgt_cmd_done(struct scsi_cmnd *cmd)
{
	struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;

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

	scsi_tgt_uspace_send_status(cmd, tcmd->itn_id, tcmd->tag);

	if (cmd->request_buffer)
		scsi_free_sgtable(cmd);

	queue_work(scsi_tgtd, &tcmd->work);
}

static int scsi_tgt_transfer_response(struct scsi_cmnd *cmd)