bsg-lib.c

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/*
 *  BSG helper library
 *
 *  Copyright (C) 2008   James Smart, Emulex Corporation
 *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
 *  Copyright (C) 2011   Mike Christie
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>
#include <linux/bsg-lib.h>
#include <linux/export.h>
#include <scsi/scsi_cmnd.h>

static void bsg_destroy_job(struct bsg_job *job)
{
    put_device(job->dev);   /* release reference for the request */

    kfree(job->request_payload.sg_list);
    kfree(job->reply_payload.sg_list);
    kfree(job);
}

void bsg_job_done(struct bsg_job *job, int result,
          unsigned int reply_payload_rcv_len)
{
    struct request *req = job->req;
    struct request *rsp = req->next_rq;
    int err;

    err = job->req->errors = result;
    if (err < 0)
        /* we're only returning the result field in the reply */
        job->req->sense_len = sizeof(u32);
    else
        job->req->sense_len = job->reply_len;
    /* we assume all request payload was transferred, residual == 0 */
    req->resid_len = 0;

    if (rsp) {
        WARN_ON(reply_payload_rcv_len > rsp->resid_len);

        /* set reply (bidi) residual */
        rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
    }
    blk_complete_request(req);
}
EXPORT_SYMBOL_GPL(bsg_job_done);

static void bsg_softirq_done(struct request *rq)
{
    struct bsg_job *job = rq->special;

    blk_end_request_all(rq, rq->errors);
    bsg_destroy_job(job);
}

static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
{
    size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);

    BUG_ON(!req->nr_phys_segments);

    buf->sg_list = kzalloc(sz, GFP_KERNEL);
    if (!buf->sg_list)
        return -ENOMEM;
    sg_init_table(buf->sg_list, req->nr_phys_segments);
    buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
    buf->payload_len = blk_rq_bytes(req);
    return 0;
}

static int bsg_create_job(struct device *dev, struct request *req)
{
    struct request *rsp = req->next_rq;
    struct request_queue *q = req->q;
    struct bsg_job *job;
    int ret;

    BUG_ON(req->special);

    job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
    if (!job)
        return -ENOMEM;

    req->special = job;
    job->req = req;
    if (q->bsg_job_size)
        job->dd_data = (void *)&job[1];
    job->request = req->cmd;
    job->request_len = req->cmd_len;
    job->reply = req->sense;
    job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
                         * allocated */
    if (req->bio) {
        ret = bsg_map_buffer(&job->request_payload, req);
        if (ret)
            goto failjob_rls_job;
    }
    if (rsp && rsp->bio) {
        ret = bsg_map_buffer(&job->reply_payload, rsp);
        if (ret)
            goto failjob_rls_rqst_payload;
    }
    job->dev = dev;
    /* take a reference for the request */
    get_device(job->dev);
    return 0;

failjob_rls_rqst_payload:
    kfree(job->request_payload.sg_list);
failjob_rls_job:
    kfree(job);
    return -ENOMEM;
}

/*
 * bsg_goose_queue - restart queue in case it was stopped
 * @q: request q to be restarted
 */
void bsg_goose_queue(struct request_queue *q)
{
    if (!q)
        return;

    blk_run_queue_async(q);
}
EXPORT_SYMBOL_GPL(bsg_goose_queue);

void bsg_request_fn(struct request_queue *q)
{
    struct device *dev = q->queuedata;
    struct request *req;
    struct bsg_job *job;
    int ret;

    if (!get_device(dev))
        return;

    while (1) {
        req = blk_fetch_request(q);
        if (!req)
            break;
        spin_unlock_irq(q->queue_lock);

        ret = bsg_create_job(dev, req);
        if (ret) {
            req->errors = ret;
            blk_end_request_all(req, ret);
            spin_lock_irq(q->queue_lock);
            continue;
        }

        job = req->special;
        ret = q->bsg_job_fn(job);
        spin_lock_irq(q->queue_lock);
        if (ret)
            break;
    }

    spin_unlock_irq(q->queue_lock);
    put_device(dev);
    spin_lock_irq(q->queue_lock);
}
EXPORT_SYMBOL_GPL(bsg_request_fn);

int bsg_setup_queue(struct device *dev, struct request_queue *q,
            char *name, bsg_job_fn *job_fn, int dd_job_size)
{
    int ret;

    q->queuedata = dev;
    q->bsg_job_size = dd_job_size;
    q->bsg_job_fn = job_fn;
    queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
    blk_queue_softirq_done(q, bsg_softirq_done);
    blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);

    ret = bsg_register_queue(q, dev, name, NULL);
    if (ret) {
        printk(KERN_ERR "%s: bsg interface failed to "
               "initialize - register queue\n", dev->kobj.name);
        return ret;
    }

    return 0;
}
EXPORT_SYMBOL_GPL(bsg_setup_queue);