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/module.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 bsg_job *job)
  36 {
  37         put_device(job->dev);   /* release reference for the request */
  38
  39         kfree(job->request_payload.sg_list);
  40         kfree(job->reply_payload.sg_list);
  41         kfree(job);
  42 }
  43
  44 /**
  45  * bsg_job_done - completion routine for bsg requests
  46  * @job: bsg_job that is complete
  47  * @result: job reply result
  48  * @reply_payload_rcv_len: length of payload recvd
  49  *
  50  * The LLD should call this when the bsg job has completed.
  51  */
  52 void bsg_job_done(struct bsg_job *job, int result,
  53                   unsigned int reply_payload_rcv_len)
  54 {
  55         struct request *req = job->req;
  56         struct request *rsp = req->next_rq;
  57         int err;
  58
  59         err = job->req->errors = result;
  60         if (err < 0)
  61                 /* we're only returning the result field in the reply */
  62                 job->req->sense_len = sizeof(u32);
  63         else
  64                 job->req->sense_len = job->reply_len;
  65         /* we assume all request payload was transferred, residual == 0 */
  66         req->resid_len = 0;
  67
  68         if (rsp) {
  69                 WARN_ON(reply_payload_rcv_len > rsp->resid_len);
  70
  71                 /* set reply (bidi) residual */
  72                 rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
  73         }
  74         blk_complete_request(req);
  75 }
  76 EXPORT_SYMBOL_GPL(bsg_job_done);
  77
  78 /**
  79  * bsg_softirq_done - softirq done routine for destroying the bsg requests
  80  * @rq: BSG request that holds the job to be destroyed
  81  */
  82 static void bsg_softirq_done(struct request *rq)
  83 {
  84         struct bsg_job *job = rq->special;
  85
  86         blk_end_request_all(rq, rq->errors);
  87         bsg_destroy_job(job);
  88 }
  89
  90 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
  91 {
  92         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
  93
  94         BUG_ON(!req->nr_phys_segments);
  95
  96         buf->sg_list = kzalloc(sz, GFP_KERNEL);
  97         if (!buf->sg_list)
  98                 return -ENOMEM;
  99         sg_init_table(buf->sg_list, req->nr_phys_segments);
 100         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 101         buf->payload_len = blk_rq_bytes(req);
 102         return 0;
 103 }
 104
 105 /**
 106  * bsg_create_job - create the bsg_job structure for the bsg request
 107  * @dev: device that is being sent the bsg request
 108  * @req: BSG request that needs a job structure
 109  */
 110 static int bsg_create_job(struct device *dev, struct request *req)
 111 {
 112         struct request *rsp = req->next_rq;
 113         struct request_queue *q = req->q;
 114         struct bsg_job *job;
 115         int ret;
 116
 117         BUG_ON(req->special);
 118
 119         job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
 120         if (!job)
 121                 return -ENOMEM;
 122
 123         req->special = job;
 124         job->req = req;
 125         if (q->bsg_job_size)
 126                 job->dd_data = (void *)&job[1];
 127         job->request = req->cmd;
 128         job->request_len = req->cmd_len;
 129         job->reply = req->sense;
 130         job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
 131                                                  * allocated */
 132         if (req->bio) {
 133                 ret = bsg_map_buffer(&job->request_payload, req);
 134                 if (ret)
 135                         goto failjob_rls_job;
 136         }
 137         if (rsp && rsp->bio) {
 138                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 139                 if (ret)
 140                         goto failjob_rls_rqst_payload;
 141         }
 142         job->dev = dev;
 143         /* take a reference for the request */
 144         get_device(job->dev);
 145         return 0;
 146
 147 failjob_rls_rqst_payload:
 148         kfree(job->request_payload.sg_list);
 149 failjob_rls_job:
 150         kfree(job);
 151         return -ENOMEM;
 152 }
 153
 154 /*
 155  * bsg_goose_queue - restart queue in case it was stopped
 156  * @q: request q to be restarted
 157  */
 158 void bsg_goose_queue(struct request_queue *q)
 159 {
 160         if (!q)
 161                 return;
 162
 163         blk_run_queue_async(q);
 164 }
 165 EXPORT_SYMBOL_GPL(bsg_goose_queue);
 166
 167 /**
 168  * bsg_request_fn - generic handler for bsg requests
 169  * @q: request queue to manage
 170  *
 171  * On error the create_bsg_job function should return a -Exyz error value
 172  * that will be set to the req->errors.
 173  *
 174  * Drivers/subsys should pass this to the queue init function.
 175  */
 176 void bsg_request_fn(struct request_queue *q)
 177 {
 178         struct device *dev = q->queuedata;
 179         struct request *req;
 180         struct bsg_job *job;
 181         int ret;
 182
 183         if (!get_device(dev))
 184                 return;
 185
 186         while (1) {
 187                 req = blk_fetch_request(q);
 188                 if (!req)
 189                         break;
 190                 spin_unlock_irq(q->queue_lock);
 191
 192                 ret = bsg_create_job(dev, req);
 193                 if (ret) {
 194                         req->errors = ret;
 195                         blk_end_request_all(req, ret);
 196                         spin_lock_irq(q->queue_lock);
 197                         continue;
 198                 }
 199
 200                 job = req->special;
 201                 ret = q->bsg_job_fn(job);
 202                 spin_lock_irq(q->queue_lock);
 203                 if (ret)
 204                         break;
 205         }
 206
 207         spin_unlock_irq(q->queue_lock);
 208         put_device(dev);
 209         spin_lock_irq(q->queue_lock);
 210 }
 211 EXPORT_SYMBOL_GPL(bsg_request_fn);
 212
 213 /**
 214  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 215  * @dev: device to attach bsg device to
 216  * @q: request queue setup by caller
 217  * @name: device to give bsg device
 218  * @job_fn: bsg job handler
 219  * @dd_job_size: size of LLD data needed for each job
 220  *
 221  * The caller should have setup the reuqest queue with bsg_request_fn
 222  * as the request_fn.
 223  */
 224 int bsg_setup_queue(struct device *dev, struct request_queue *q,
 225                     char *name, bsg_job_fn *job_fn, int dd_job_size)
 226 {
 227         int ret;
 228
 229         q->queuedata = dev;
 230         q->bsg_job_size = dd_job_size;
 231         q->bsg_job_fn = job_fn;
 232         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 233         blk_queue_softirq_done(q, bsg_softirq_done);
 234         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 235
 236         ret = bsg_register_queue(q, dev, name, NULL);
 237         if (ret) {
 238                 printk(KERN_ERR "%s: bsg interface failed to "
 239                        "initialize - register queue\n", dev->kobj.name);
 240                 return ret;
 241         }
 242
 243         return 0;
 244 }
 245 EXPORT_SYMBOL_GPL(bsg_setup_queue);
 246
 247 /**
 248  * bsg_remove_queue - Deletes the bsg dev from the q
 249  * @q:  the request_queue that is to be torn down.
 250  *
 251  * Notes:
 252  *   Before unregistering the queue empty any requests that are blocked
 253  */
 254 void bsg_remove_queue(struct request_queue *q)
 255 {
 256         struct request *req; /* block request */
 257         int counts; /* totals for request_list count and starved */
 258
 259         if (!q)
 260                 return;
 261
 262         /* Stop taking in new requests */
 263         spin_lock_irq(q->queue_lock);
 264         blk_stop_queue(q);
 265
 266         /* drain all requests in the queue */
 267         while (1) {
 268                 /* need the lock to fetch a request
 269                  * this may fetch the same reqeust as the previous pass
 270                  */
 271                 req = blk_fetch_request(q);
 272                 /* save requests in use and starved */
 273                 counts = q->rq.count[0] + q->rq.count[1] +
 274                          q->rq.starved[0] + q->rq.starved[1];
 275                 spin_unlock_irq(q->queue_lock);
 276                 /* any requests still outstanding? */
 277                 if (counts == 0)
 278                         break;
 279
 280                 /* This may be the same req as the previous iteration,
 281                  * always send the blk_end_request_all after a prefetch.
 282                  * It is not okay to not end the request because the
 283                  * prefetch started the request.
 284                  */
 285                 if (req) {
 286                         /* return -ENXIO to indicate that this queue is
 287                          * going away
 288                          */
 289                         req->errors = -ENXIO;
 290                         blk_end_request_all(req, -ENXIO);
 291                 }
 292
 293                 msleep(200); /* allow bsg to possibly finish */
 294                 spin_lock_irq(q->queue_lock);
 295         }
 296         bsg_unregister_queue(q);
 297 }
 298 EXPORT_SYMBOL_GPL(bsg_remove_queue);