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 void bsg_softirq_done(struct request *rq)
 100 {
 101         struct bsg_job *job = rq->special;
 102
 103         bsg_job_put(job);
 104 }
 105 EXPORT_SYMBOL_GPL(bsg_softirq_done);
 106
 107 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 108 {
 109         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 110
 111         BUG_ON(!req->nr_phys_segments);
 112
 113         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 114         if (!buf->sg_list)
 115                 return -ENOMEM;
 116         sg_init_table(buf->sg_list, req->nr_phys_segments);
 117         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 118         buf->payload_len = blk_rq_bytes(req);
 119         return 0;
 120 }
 121
 122 /**
 123  * bsg_create_job - create the bsg_job structure for the bsg request
 124  * @dev: device that is being sent the bsg request
 125  * @req: BSG request that needs a job structure
 126  */
 127 static int bsg_create_job(struct device *dev, struct request *req)
 128 {
 129         struct request *rsp = req->next_rq;
 130         struct request_queue *q = req->q;
 131         struct bsg_job *job;
 132         int ret;
 133
 134         BUG_ON(req->special);
 135
 136         job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
 137         if (!job)
 138                 return -ENOMEM;
 139
 140         req->special = job;
 141         job->req = req;
 142         if (q->bsg_job_size)
 143                 job->dd_data = (void *)&job[1];
 144         job->request = req->cmd;
 145         job->request_len = req->cmd_len;
 146         job->reply = req->sense;
 147         job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
 148                                                  * allocated */
 149         if (req->bio) {
 150                 ret = bsg_map_buffer(&job->request_payload, req);
 151                 if (ret)
 152                         goto failjob_rls_job;
 153         }
 154         if (rsp && rsp->bio) {
 155                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 156                 if (ret)
 157                         goto failjob_rls_rqst_payload;
 158         }
 159         job->dev = dev;
 160         /* take a reference for the request */
 161         get_device(job->dev);
 162         kref_init(&job->kref);
 163         return 0;
 164
 165 failjob_rls_rqst_payload:
 166         kfree(job->request_payload.sg_list);
 167 failjob_rls_job:
 168         kfree(job);
 169         return -ENOMEM;
 170 }
 171
 172 /**
 173  * bsg_request_fn - generic handler for bsg requests
 174  * @q: request queue to manage
 175  *
 176  * On error the create_bsg_job function should return a -Exyz error value
 177  * that will be set to the req->errors.
 178  *
 179  * Drivers/subsys should pass this to the queue init function.
 180  */
 181 void bsg_request_fn(struct request_queue *q)
 182 {
 183         struct device *dev = q->queuedata;
 184         struct request *req;
 185         struct bsg_job *job;
 186         int ret;
 187
 188         if (!get_device(dev))
 189                 return;
 190
 191         while (1) {
 192                 req = blk_fetch_request(q);
 193                 if (!req)
 194                         break;
 195                 spin_unlock_irq(q->queue_lock);
 196
 197                 ret = bsg_create_job(dev, req);
 198                 if (ret) {
 199                         req->errors = ret;
 200                         blk_end_request_all(req, ret);
 201                         spin_lock_irq(q->queue_lock);
 202                         continue;
 203                 }
 204
 205                 job = req->special;
 206                 ret = q->bsg_job_fn(job);
 207                 spin_lock_irq(q->queue_lock);
 208                 if (ret)
 209                         break;
 210         }
 211
 212         spin_unlock_irq(q->queue_lock);
 213         put_device(dev);
 214         spin_lock_irq(q->queue_lock);
 215 }
 216 EXPORT_SYMBOL_GPL(bsg_request_fn);
 217
 218 /**
 219  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 220  * @dev: device to attach bsg device to
 221  * @q: request queue setup by caller
 222  * @name: device to give bsg device
 223  * @job_fn: bsg job handler
 224  * @dd_job_size: size of LLD data needed for each job
 225  *
 226  * The caller should have setup the reuqest queue with bsg_request_fn
 227  * as the request_fn.
 228  */
 229 int bsg_setup_queue(struct device *dev, struct request_queue *q,
 230                     char *name, bsg_job_fn *job_fn, int dd_job_size)
 231 {
 232         int ret;
 233
 234         q->queuedata = dev;
 235         q->bsg_job_size = dd_job_size;
 236         q->bsg_job_fn = job_fn;
 237         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 238         blk_queue_softirq_done(q, bsg_softirq_done);
 239         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 240
 241         ret = bsg_register_queue(q, dev, name, NULL);
 242         if (ret) {
 243                 printk(KERN_ERR "%s: bsg interface failed to "
 244                        "initialize - register queue\n", dev->kobj.name);
 245                 return ret;
 246         }
 247
 248         return 0;
 249 }
 250 EXPORT_SYMBOL_GPL(bsg_setup_queue);