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 static 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
  49 void bsg_job_put(struct bsg_job *job)
  50 {
  51         kref_put(&job->kref, bsg_destroy_job);
  52 }
  53 EXPORT_SYMBOL_GPL(bsg_job_put);
  54
  55 int bsg_job_get(struct bsg_job *job)
  56 {
  57         return kref_get_unless_zero(&job->kref);
  58 }
  59 EXPORT_SYMBOL_GPL(bsg_job_get);
  60
  61 /**
  62  * bsg_job_done - completion routine for bsg requests
  63  * @job: bsg_job that is complete
  64  * @result: job reply result
  65  * @reply_payload_rcv_len: length of payload recvd
  66  *
  67  * The LLD should call this when the bsg job has completed.
  68  */
  69 void bsg_job_done(struct bsg_job *job, int result,
  70                   unsigned int reply_payload_rcv_len)
  71 {
  72         struct request *req = job->req;
  73         struct request *rsp = req->next_rq;
  74         int err;
  75
  76         err = job->req->errors = result;
  77         if (err < 0)
  78                 /* we're only returning the result field in the reply */
  79                 job->req->sense_len = sizeof(u32);
  80         else
  81                 job->req->sense_len = job->reply_len;
  82         /* we assume all request payload was transferred, residual == 0 */
  83         req->resid_len = 0;
  84
  85         if (rsp) {
  86                 WARN_ON(reply_payload_rcv_len > rsp->resid_len);
  87
  88                 /* set reply (bidi) residual */
  89                 rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
  90         }
  91         blk_complete_request(req);
  92 }
  93 EXPORT_SYMBOL_GPL(bsg_job_done);
  94
  95 /**
  96  * bsg_softirq_done - softirq done routine for destroying the bsg requests
  97  * @rq: BSG request that holds the job to be destroyed
  98  */
  99 static void bsg_softirq_done(struct request *rq)
 100 {
 101         struct bsg_job *job = rq->special;
 102
 103         bsg_job_put(job);
 104 }
 105
 106 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 107 {
 108         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 109
 110         BUG_ON(!req->nr_phys_segments);
 111
 112         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 113         if (!buf->sg_list)
 114                 return -ENOMEM;
 115         sg_init_table(buf->sg_list, req->nr_phys_segments);
 116         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 117         buf->payload_len = blk_rq_bytes(req);
 118         return 0;
 119 }
 120
 121 /**
 122  * bsg_create_job - create the bsg_job structure for the bsg request
 123  * @dev: device that is being sent the bsg request
 124  * @req: BSG request that needs a job structure
 125  */
 126 static int bsg_create_job(struct device *dev, struct request *req)
 127 {
 128         struct request *rsp = req->next_rq;
 129         struct request_queue *q = req->q;
 130         struct bsg_job *job;
 131         int ret;
 132
 133         BUG_ON(req->special);
 134
 135         job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
 136         if (!job)
 137                 return -ENOMEM;
 138
 139         req->special = job;
 140         job->req = req;
 141         if (q->bsg_job_size)
 142                 job->dd_data = (void *)&job[1];
 143         job->request = req->cmd;
 144         job->request_len = req->cmd_len;
 145         job->reply = req->sense;
 146         job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
 147                                                  * allocated */
 148         if (req->bio) {
 149                 ret = bsg_map_buffer(&job->request_payload, req);
 150                 if (ret)
 151                         goto failjob_rls_job;
 152         }
 153         if (rsp && rsp->bio) {
 154                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 155                 if (ret)
 156                         goto failjob_rls_rqst_payload;
 157         }
 158         job->dev = dev;
 159         /* take a reference for the request */
 160         get_device(job->dev);
 161         kref_init(&job->kref);
 162         return 0;
 163
 164 failjob_rls_rqst_payload:
 165         kfree(job->request_payload.sg_list);
 166 failjob_rls_job:
 167         kfree(job);
 168         return -ENOMEM;
 169 }
 170
 171 /**
 172  * bsg_request_fn - generic handler for bsg requests
 173  * @q: request queue to manage
 174  *
 175  * On error the create_bsg_job function should return a -Exyz error value
 176  * that will be set to the req->errors.
 177  *
 178  * Drivers/subsys should pass this to the queue init function.
 179  */
 180 void bsg_request_fn(struct request_queue *q)
 181         __releases(q->queue_lock)
 182         __acquires(q->queue_lock)
 183 {
 184         struct device *dev = q->queuedata;
 185         struct request *req;
 186         struct bsg_job *job;
 187         int ret;
 188
 189         if (!get_device(dev))
 190                 return;
 191
 192         while (1) {
 193                 req = blk_fetch_request(q);
 194                 if (!req)
 195                         break;
 196                 spin_unlock_irq(q->queue_lock);
 197
 198                 ret = bsg_create_job(dev, req);
 199                 if (ret) {
 200                         req->errors = ret;
 201                         blk_end_request_all(req, ret);
 202                         spin_lock_irq(q->queue_lock);
 203                         continue;
 204                 }
 205
 206                 job = req->special;
 207                 ret = q->bsg_job_fn(job);
 208                 spin_lock_irq(q->queue_lock);
 209                 if (ret)
 210                         break;
 211         }
 212
 213         spin_unlock_irq(q->queue_lock);
 214         put_device(dev);
 215         spin_lock_irq(q->queue_lock);
 216 }
 217 EXPORT_SYMBOL_GPL(bsg_request_fn);
 218
 219 /**
 220  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 221  * @dev: device to attach bsg device to
 222  * @q: request queue setup by caller
 223  * @name: device to give bsg device
 224  * @job_fn: bsg job handler
 225  * @dd_job_size: size of LLD data needed for each job
 226  *
 227  * The caller should have setup the reuqest queue with bsg_request_fn
 228  * as the request_fn.
 229  */
 230 int bsg_setup_queue(struct device *dev, struct request_queue *q,
 231                     char *name, bsg_job_fn *job_fn, int dd_job_size)
 232 {
 233         int ret;
 234
 235         q->queuedata = dev;
 236         q->bsg_job_size = dd_job_size;
 237         q->bsg_job_fn = job_fn;
 238         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 239         blk_queue_softirq_done(q, bsg_softirq_done);
 240         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 241
 242         ret = bsg_register_queue(q, dev, name, NULL);
 243         if (ret) {
 244                 printk(KERN_ERR "%s: bsg interface failed to "
 245                        "initialize - register queue\n", dev->kobj.name);
 246                 return ret;
 247         }
 248
 249         return 0;
 250 }
 251 EXPORT_SYMBOL_GPL(bsg_setup_queue);