block/bsg-lib.c

   1 /*
   2  *  BSG helper library
   3  *
   4  *  Copyright (C) 2008   James Smart, Emulex Corporation
   5  *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
   6  *  Copyright (C) 2011   Mike Christie
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  */
  23 #include <linux/slab.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/delay.h>
  26 #include <linux/scatterlist.h>
  27 #include <linux/bsg-lib.h>
  28 #include <linux/export.h>
  29 #include <scsi/scsi_cmnd.h>
  30
  31 /**
  32  * bsg_destroy_job - routine to teardown/delete a bsg job
  33  * @job: bsg_job that is to be torn down
  34  */
  35 void bsg_destroy_job(struct kref *kref)
  36 {
  37         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
  38         struct request *rq = job->req;
  39
  40         blk_end_request_all(rq, rq->errors);
  41
  42         put_device(job->dev);   /* release reference for the request */
  43
  44         kfree(job->request_payload.sg_list);
  45         kfree(job->reply_payload.sg_list);
  46         kfree(job);
  47 }
  48 EXPORT_SYMBOL_GPL(bsg_destroy_job);
  49
  50 /**
  51  * bsg_job_done - completion routine for bsg requests
  52  * @job: bsg_job that is complete
  53  * @result: job reply result
  54  * @reply_payload_rcv_len: length of payload recvd
  55  *
  56  * The LLD should call this when the bsg job has completed.
  57  */
  58 void bsg_job_done(struct bsg_job *job, int result,
  59                   unsigned int reply_payload_rcv_len)
  60 {
  61         struct request *req = job->req;
  62         struct request *rsp = req->next_rq;
  63         int err;
  64
  65         err = job->req->errors = result;
  66         if (err < 0)
  67                 /* we're only returning the result field in the reply */
  68                 job->req->sense_len = sizeof(u32);
  69         else
  70                 job->req->sense_len = job->reply_len;
  71         /* we assume all request payload was transferred, residual == 0 */
  72         req->resid_len = 0;
  73
  74         if (rsp) {
  75                 WARN_ON(reply_payload_rcv_len > rsp->resid_len);
  76
  77                 /* set reply (bidi) residual */
  78                 rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
  79         }
  80         blk_complete_request(req);
  81 }
  82 EXPORT_SYMBOL_GPL(bsg_job_done);
  83
  84 /**
  85  * bsg_softirq_done - softirq done routine for destroying the bsg requests
  86  * @rq: BSG request that holds the job to be destroyed
  87  */
  88 void bsg_softirq_done(struct request *rq)
  89 {
  90         struct bsg_job *job = rq->special;
  91
  92         kref_put(&job->kref, bsg_destroy_job);
  93 }
  94 EXPORT_SYMBOL_GPL(bsg_softirq_done);
  95
  96 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
  97 {
  98         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
  99
 100         BUG_ON(!req->nr_phys_segments);
 101
 102         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 103         if (!buf->sg_list)
 104                 return -ENOMEM;
 105         sg_init_table(buf->sg_list, req->nr_phys_segments);
 106         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 107         buf->payload_len = blk_rq_bytes(req);
 108         return 0;
 109 }
 110
 111 /**
 112  * bsg_create_job - create the bsg_job structure for the bsg request
 113  * @dev: device that is being sent the bsg request
 114  * @req: BSG request that needs a job structure
 115  */
 116 static int bsg_create_job(struct device *dev, struct request *req)
 117 {
 118         struct request *rsp = req->next_rq;
 119         struct request_queue *q = req->q;
 120         struct bsg_job *job;
 121         int ret;
 122
 123         BUG_ON(req->special);
 124
 125         job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
 126         if (!job)
 127                 return -ENOMEM;
 128
 129         req->special = job;
 130         job->req = req;
 131         if (q->bsg_job_size)
 132                 job->dd_data = (void *)&job[1];
 133         job->request = req->cmd;
 134         job->request_len = req->cmd_len;
 135         job->reply = req->sense;
 136         job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
 137                                                  * allocated */
 138         if (req->bio) {
 139                 ret = bsg_map_buffer(&job->request_payload, req);
 140                 if (ret)
 141                         goto failjob_rls_job;
 142         }
 143         if (rsp && rsp->bio) {
 144                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 145                 if (ret)
 146                         goto failjob_rls_rqst_payload;
 147         }
 148         job->dev = dev;
 149         /* take a reference for the request */
 150         get_device(job->dev);
 151         kref_init(&job->kref);
 152         return 0;
 153
 154 failjob_rls_rqst_payload:
 155         kfree(job->request_payload.sg_list);
 156 failjob_rls_job:
 157         kfree(job);
 158         return -ENOMEM;
 159 }
 160
 161 /**
 162  * bsg_request_fn - generic handler for bsg requests
 163  * @q: request queue to manage
 164  *
 165  * On error the create_bsg_job function should return a -Exyz error value
 166  * that will be set to the req->errors.
 167  *
 168  * Drivers/subsys should pass this to the queue init function.
 169  */
 170 void bsg_request_fn(struct request_queue *q)
 171 {
 172         struct device *dev = q->queuedata;
 173         struct request *req;
 174         struct bsg_job *job;
 175         int ret;
 176
 177         if (!get_device(dev))
 178                 return;
 179
 180         while (1) {
 181                 req = blk_fetch_request(q);
 182                 if (!req)
 183                         break;
 184                 spin_unlock_irq(q->queue_lock);
 185
 186                 ret = bsg_create_job(dev, req);
 187                 if (ret) {
 188                         req->errors = ret;
 189                         blk_end_request_all(req, ret);
 190                         spin_lock_irq(q->queue_lock);
 191                         continue;
 192                 }
 193
 194                 job = req->special;
 195                 ret = q->bsg_job_fn(job);
 196                 spin_lock_irq(q->queue_lock);
 197                 if (ret)
 198                         break;
 199         }
 200
 201         spin_unlock_irq(q->queue_lock);
 202         put_device(dev);
 203         spin_lock_irq(q->queue_lock);
 204 }
 205 EXPORT_SYMBOL_GPL(bsg_request_fn);
 206
 207 /**
 208  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 209  * @dev: device to attach bsg device to
 210  * @q: request queue setup by caller
 211  * @name: device to give bsg device
 212  * @job_fn: bsg job handler
 213  * @dd_job_size: size of LLD data needed for each job
 214  *
 215  * The caller should have setup the reuqest queue with bsg_request_fn
 216  * as the request_fn.
 217  */
 218 int bsg_setup_queue(struct device *dev, struct request_queue *q,
 219                     char *name, bsg_job_fn *job_fn, int dd_job_size)
 220 {
 221         int ret;
 222
 223         q->queuedata = dev;
 224         q->bsg_job_size = dd_job_size;
 225         q->bsg_job_fn = job_fn;
 226         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 227         blk_queue_softirq_done(q, bsg_softirq_done);
 228         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 229
 230         ret = bsg_register_queue(q, dev, name, NULL);
 231         if (ret) {
 232                 printk(KERN_ERR "%s: bsg interface failed to "
 233                        "initialize - register queue\n", dev->kobj.name);
 234                 return ret;
 235         }
 236
 237         return 0;
 238 }
 239 EXPORT_SYMBOL_GPL(bsg_setup_queue);