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         struct scsi_request *rq = scsi_req(req);
  75         int err;
  76
  77         err = job->req->errors = result;
  78         if (err < 0)
  79                 /* we're only returning the result field in the reply */
  80                 rq->sense_len = sizeof(u32);
  81         else
  82                 rq->sense_len = job->reply_len;
  83         /* we assume all request payload was transferred, residual == 0 */
  84         rq->resid_len = 0;
  85
  86         if (rsp) {
  87                 WARN_ON(reply_payload_rcv_len > scsi_req(rsp)->resid_len);
  88
  89                 /* set reply (bidi) residual */
  90                 scsi_req(rsp)->resid_len -=
  91                         min(reply_payload_rcv_len, scsi_req(rsp)->resid_len);
  92         }
  93         blk_complete_request(req);
  94 }
  95 EXPORT_SYMBOL_GPL(bsg_job_done);
  96
  97 /**
  98  * bsg_softirq_done - softirq done routine for destroying the bsg requests
  99  * @rq: BSG request that holds the job to be destroyed
 100  */
 101 static void bsg_softirq_done(struct request *rq)
 102 {
 103         struct bsg_job *job = rq->special;
 104
 105         bsg_job_put(job);
 106 }
 107
 108 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 109 {
 110         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 111
 112         BUG_ON(!req->nr_phys_segments);
 113
 114         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 115         if (!buf->sg_list)
 116                 return -ENOMEM;
 117         sg_init_table(buf->sg_list, req->nr_phys_segments);
 118         scsi_req(req)->resid_len = blk_rq_bytes(req);
 119         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 120         buf->payload_len = blk_rq_bytes(req);
 121         return 0;
 122 }
 123
 124 /**
 125  * bsg_create_job - create the bsg_job structure for the bsg request
 126  * @dev: device that is being sent the bsg request
 127  * @req: BSG request that needs a job structure
 128  */
 129 static int bsg_create_job(struct device *dev, struct request *req)
 130 {
 131         struct request *rsp = req->next_rq;
 132         struct request_queue *q = req->q;
 133         struct scsi_request *rq = scsi_req(req);
 134         struct bsg_job *job;
 135         int ret;
 136
 137         BUG_ON(req->special);
 138
 139         job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
 140         if (!job)
 141                 return -ENOMEM;
 142
 143         req->special = job;
 144         job->req = req;
 145         if (q->bsg_job_size)
 146                 job->dd_data = (void *)&job[1];
 147         job->request = rq->cmd;
 148         job->request_len = rq->cmd_len;
 149         job->reply = rq->sense;
 150         job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
 151                                                  * allocated */
 152         if (req->bio) {
 153                 ret = bsg_map_buffer(&job->request_payload, req);
 154                 if (ret)
 155                         goto failjob_rls_job;
 156         }
 157         if (rsp && rsp->bio) {
 158                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 159                 if (ret)
 160                         goto failjob_rls_rqst_payload;
 161         }
 162         job->dev = dev;
 163         /* take a reference for the request */
 164         get_device(job->dev);
 165         kref_init(&job->kref);
 166         return 0;
 167
 168 failjob_rls_rqst_payload:
 169         kfree(job->request_payload.sg_list);
 170 failjob_rls_job:
 171         kfree(job);
 172         return -ENOMEM;
 173 }
 174
 175 /**
 176  * bsg_request_fn - generic handler for bsg requests
 177  * @q: request queue to manage
 178  *
 179  * On error the create_bsg_job function should return a -Exyz error value
 180  * that will be set to the req->errors.
 181  *
 182  * Drivers/subsys should pass this to the queue init function.
 183  */
 184 static void bsg_request_fn(struct request_queue *q)
 185         __releases(q->queue_lock)
 186         __acquires(q->queue_lock)
 187 {
 188         struct device *dev = q->queuedata;
 189         struct request *req;
 190         struct bsg_job *job;
 191         int ret;
 192
 193         if (!get_device(dev))
 194                 return;
 195
 196         while (1) {
 197                 req = blk_fetch_request(q);
 198                 if (!req)
 199                         break;
 200                 spin_unlock_irq(q->queue_lock);
 201
 202                 ret = bsg_create_job(dev, req);
 203                 if (ret) {
 204                         req->errors = ret;
 205                         blk_end_request_all(req, ret);
 206                         spin_lock_irq(q->queue_lock);
 207                         continue;
 208                 }
 209
 210                 job = req->special;
 211                 ret = q->bsg_job_fn(job);
 212                 spin_lock_irq(q->queue_lock);
 213                 if (ret)
 214                         break;
 215         }
 216
 217         spin_unlock_irq(q->queue_lock);
 218         put_device(dev);
 219         spin_lock_irq(q->queue_lock);
 220 }
 221
 222 /**
 223  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 224  * @dev: device to attach bsg device to
 225  * @name: device to give bsg device
 226  * @job_fn: bsg job handler
 227  * @dd_job_size: size of LLD data needed for each job
 228  */
 229 struct request_queue *bsg_setup_queue(struct device *dev, char *name,
 230                 bsg_job_fn *job_fn, int dd_job_size)
 231 {
 232         struct request_queue *q;
 233         int ret;
 234
 235         q = blk_alloc_queue(GFP_KERNEL);
 236         if (!q)
 237                 return ERR_PTR(-ENOMEM);
 238         q->cmd_size = sizeof(struct scsi_request);
 239         q->request_fn = bsg_request_fn;
 240
 241         ret = blk_init_allocated_queue(q);
 242         if (ret)
 243                 goto out_cleanup_queue;
 244
 245         q->queuedata = dev;
 246         q->bsg_job_size = dd_job_size;
 247         q->bsg_job_fn = job_fn;
 248         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 249         blk_queue_softirq_done(q, bsg_softirq_done);
 250         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 251
 252         ret = bsg_register_queue(q, dev, name, NULL);
 253         if (ret) {
 254                 printk(KERN_ERR "%s: bsg interface failed to "
 255                        "initialize - register queue\n", dev->kobj.name);
 256                 goto out_cleanup_queue;
 257         }
 258
 259         return q;
 260 out_cleanup_queue:
 261         blk_cleanup_queue(q);
 262         return ERR_PTR(ret);
 263 }
 264 EXPORT_SYMBOL_GPL(bsg_setup_queue);