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/blk-mq.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 #include <scsi/sg.h>
  31
  32 #define uptr64(val) ((void __user *)(uintptr_t)(val))
  33
  34 struct bsg_set {
  35         struct blk_mq_tag_set   tag_set;
  36         bsg_job_fn              *job_fn;
  37         bsg_timeout_fn          *timeout_fn;
  38 };
  39
  40 static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
  41 {
  42         if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
  43             hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
  44                 return -EINVAL;
  45         if (!capable(CAP_SYS_RAWIO))
  46                 return -EPERM;
  47         return 0;
  48 }
  49
  50 static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
  51                 fmode_t mode)
  52 {
  53         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
  54         int ret;
  55
  56         job->request_len = hdr->request_len;
  57         job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
  58         if (IS_ERR(job->request))
  59                 return PTR_ERR(job->request);
  60
  61         if (hdr->dout_xfer_len && hdr->din_xfer_len) {
  62                 job->bidi_rq = blk_get_request(rq->q, REQ_OP_SCSI_IN, 0);
  63                 if (IS_ERR(job->bidi_rq)) {
  64                         ret = PTR_ERR(job->bidi_rq);
  65                         goto out;
  66                 }
  67
  68                 ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
  69                                 uptr64(hdr->din_xferp), hdr->din_xfer_len,
  70                                 GFP_KERNEL);
  71                 if (ret)
  72                         goto out_free_bidi_rq;
  73
  74                 job->bidi_bio = job->bidi_rq->bio;
  75         } else {
  76                 job->bidi_rq = NULL;
  77                 job->bidi_bio = NULL;
  78         }
  79
  80         return 0;
  81
  82 out_free_bidi_rq:
  83         if (job->bidi_rq)
  84                 blk_put_request(job->bidi_rq);
  85 out:
  86         kfree(job->request);
  87         return ret;
  88 }
  89
  90 static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
  91 {
  92         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
  93         int ret = 0;
  94
  95         /*
  96          * The assignments below don't make much sense, but are kept for
  97          * bug by bug backwards compatibility:
  98          */
  99         hdr->device_status = job->result & 0xff;
 100         hdr->transport_status = host_byte(job->result);
 101         hdr->driver_status = driver_byte(job->result);
 102         hdr->info = 0;
 103         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 104                 hdr->info |= SG_INFO_CHECK;
 105         hdr->response_len = 0;
 106
 107         if (job->result < 0) {
 108                 /* we're only returning the result field in the reply */
 109                 job->reply_len = sizeof(u32);
 110                 ret = job->result;
 111         }
 112
 113         if (job->reply_len && hdr->response) {
 114                 int len = min(hdr->max_response_len, job->reply_len);
 115
 116                 if (copy_to_user(uptr64(hdr->response), job->reply, len))
 117                         ret = -EFAULT;
 118                 else
 119                         hdr->response_len = len;
 120         }
 121
 122         /* we assume all request payload was transferred, residual == 0 */
 123         hdr->dout_resid = 0;
 124
 125         if (job->bidi_rq) {
 126                 unsigned int rsp_len = job->reply_payload.payload_len;
 127
 128                 if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
 129                         hdr->din_resid = 0;
 130                 else
 131                         hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
 132         } else {
 133                 hdr->din_resid = 0;
 134         }
 135
 136         return ret;
 137 }
 138
 139 static void bsg_transport_free_rq(struct request *rq)
 140 {
 141         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 142
 143         if (job->bidi_rq) {
 144                 blk_rq_unmap_user(job->bidi_bio);
 145                 blk_put_request(job->bidi_rq);
 146         }
 147
 148         kfree(job->request);
 149 }
 150
 151 static const struct bsg_ops bsg_transport_ops = {
 152         .check_proto            = bsg_transport_check_proto,
 153         .fill_hdr               = bsg_transport_fill_hdr,
 154         .complete_rq            = bsg_transport_complete_rq,
 155         .free_rq                = bsg_transport_free_rq,
 156 };
 157
 158 /**
 159  * bsg_teardown_job - routine to teardown a bsg job
 160  * @kref: kref inside bsg_job that is to be torn down
 161  */
 162 static void bsg_teardown_job(struct kref *kref)
 163 {
 164         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
 165         struct request *rq = blk_mq_rq_from_pdu(job);
 166
 167         put_device(job->dev);   /* release reference for the request */
 168
 169         kfree(job->request_payload.sg_list);
 170         kfree(job->reply_payload.sg_list);
 171
 172         blk_mq_end_request(rq, BLK_STS_OK);
 173 }
 174
 175 void bsg_job_put(struct bsg_job *job)
 176 {
 177         kref_put(&job->kref, bsg_teardown_job);
 178 }
 179 EXPORT_SYMBOL_GPL(bsg_job_put);
 180
 181 int bsg_job_get(struct bsg_job *job)
 182 {
 183         return kref_get_unless_zero(&job->kref);
 184 }
 185 EXPORT_SYMBOL_GPL(bsg_job_get);
 186
 187 /**
 188  * bsg_job_done - completion routine for bsg requests
 189  * @job: bsg_job that is complete
 190  * @result: job reply result
 191  * @reply_payload_rcv_len: length of payload recvd
 192  *
 193  * The LLD should call this when the bsg job has completed.
 194  */
 195 void bsg_job_done(struct bsg_job *job, int result,
 196                   unsigned int reply_payload_rcv_len)
 197 {
 198         job->result = result;
 199         job->reply_payload_rcv_len = reply_payload_rcv_len;
 200         blk_mq_complete_request(blk_mq_rq_from_pdu(job));
 201 }
 202 EXPORT_SYMBOL_GPL(bsg_job_done);
 203
 204 /**
 205  * bsg_complete - softirq done routine for destroying the bsg requests
 206  * @rq: BSG request that holds the job to be destroyed
 207  */
 208 static void bsg_complete(struct request *rq)
 209 {
 210         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 211
 212         bsg_job_put(job);
 213 }
 214
 215 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 216 {
 217         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 218
 219         BUG_ON(!req->nr_phys_segments);
 220
 221         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 222         if (!buf->sg_list)
 223                 return -ENOMEM;
 224         sg_init_table(buf->sg_list, req->nr_phys_segments);
 225         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 226         buf->payload_len = blk_rq_bytes(req);
 227         return 0;
 228 }
 229
 230 /**
 231  * bsg_prepare_job - create the bsg_job structure for the bsg request
 232  * @dev: device that is being sent the bsg request
 233  * @req: BSG request that needs a job structure
 234  */
 235 static bool bsg_prepare_job(struct device *dev, struct request *req)
 236 {
 237         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 238         int ret;
 239
 240         job->timeout = req->timeout;
 241
 242         if (req->bio) {
 243                 ret = bsg_map_buffer(&job->request_payload, req);
 244                 if (ret)
 245                         goto failjob_rls_job;
 246         }
 247         if (job->bidi_rq) {
 248                 ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
 249                 if (ret)
 250                         goto failjob_rls_rqst_payload;
 251         }
 252         job->dev = dev;
 253         /* take a reference for the request */
 254         get_device(job->dev);
 255         kref_init(&job->kref);
 256         return true;
 257
 258 failjob_rls_rqst_payload:
 259         kfree(job->request_payload.sg_list);
 260 failjob_rls_job:
 261         job->result = -ENOMEM;
 262         return false;
 263 }
 264
 265 /**
 266  * bsg_queue_rq - generic handler for bsg requests
 267  * @hctx: hardware queue
 268  * @bd: queue data
 269  *
 270  * On error the create_bsg_job function should return a -Exyz error value
 271  * that will be set to ->result.
 272  *
 273  * Drivers/subsys should pass this to the queue init function.
 274  */
 275 static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
 276                                  const struct blk_mq_queue_data *bd)
 277 {
 278         struct request_queue *q = hctx->queue;
 279         struct device *dev = q->queuedata;
 280         struct request *req = bd->rq;
 281         struct bsg_set *bset =
 282                 container_of(q->tag_set, struct bsg_set, tag_set);
 283         int ret;
 284
 285         blk_mq_start_request(req);
 286
 287         if (!get_device(dev))
 288                 return BLK_STS_IOERR;
 289
 290         if (!bsg_prepare_job(dev, req))
 291                 return BLK_STS_IOERR;
 292
 293         ret = bset->job_fn(blk_mq_rq_to_pdu(req));
 294         if (ret)
 295                 return BLK_STS_IOERR;
 296
 297         put_device(dev);
 298         return BLK_STS_OK;
 299 }
 300
 301 /* called right after the request is allocated for the request_queue */
 302 static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
 303                        unsigned int hctx_idx, unsigned int numa_node)
 304 {
 305         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 306
 307         job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
 308         if (!job->reply)
 309                 return -ENOMEM;
 310         return 0;
 311 }
 312
 313 /* called right before the request is given to the request_queue user */
 314 static void bsg_initialize_rq(struct request *req)
 315 {
 316         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 317         void *reply = job->reply;
 318
 319         memset(job, 0, sizeof(*job));
 320         job->reply = reply;
 321         job->reply_len = SCSI_SENSE_BUFFERSIZE;
 322         job->dd_data = job + 1;
 323 }
 324
 325 static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
 326                        unsigned int hctx_idx)
 327 {
 328         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 329
 330         kfree(job->reply);
 331 }
 332
 333 void bsg_remove_queue(struct request_queue *q)
 334 {
 335         if (q) {
 336                 struct bsg_set *bset =
 337                         container_of(q->tag_set, struct bsg_set, tag_set);
 338
 339                 bsg_unregister_queue(q);
 340                 blk_cleanup_queue(q);
 341                 blk_mq_free_tag_set(&bset->tag_set);
 342                 kfree(bset);
 343         }
 344 }
 345 EXPORT_SYMBOL_GPL(bsg_remove_queue);
 346
 347 static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
 348 {
 349         struct bsg_set *bset =
 350                 container_of(rq->q->tag_set, struct bsg_set, tag_set);
 351
 352         if (!bset->timeout_fn)
 353                 return BLK_EH_DONE;
 354         return bset->timeout_fn(rq);
 355 }
 356
 357 static const struct blk_mq_ops bsg_mq_ops = {
 358         .queue_rq               = bsg_queue_rq,
 359         .init_request           = bsg_init_rq,
 360         .exit_request           = bsg_exit_rq,
 361         .initialize_rq_fn       = bsg_initialize_rq,
 362         .complete               = bsg_complete,
 363         .timeout                = bsg_timeout,
 364 };
 365
 366 /**
 367  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 368  * @dev: device to attach bsg device to
 369  * @name: device to give bsg device
 370  * @job_fn: bsg job handler
 371  * @dd_job_size: size of LLD data needed for each job
 372  */
 373 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 374                 bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
 375 {
 376         struct bsg_set *bset;
 377         struct blk_mq_tag_set *set;
 378         struct request_queue *q;
 379         int ret = -ENOMEM;
 380
 381         bset = kzalloc(sizeof(*bset), GFP_KERNEL);
 382         if (!bset)
 383                 return ERR_PTR(-ENOMEM);
 384
 385         bset->job_fn = job_fn;
 386         bset->timeout_fn = timeout;
 387
 388         set = &bset->tag_set;
 389         set->ops = &bsg_mq_ops,
 390         set->nr_hw_queues = 1;
 391         set->queue_depth = 128;
 392         set->numa_node = NUMA_NO_NODE;
 393         set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
 394         set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
 395         if (blk_mq_alloc_tag_set(set))
 396                 goto out_tag_set;
 397
 398         q = blk_mq_init_queue(set);
 399         if (IS_ERR(q)) {
 400                 ret = PTR_ERR(q);
 401                 goto out_queue;
 402         }
 403
 404         q->queuedata = dev;
 405         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 406
 407         ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
 408         if (ret) {
 409                 printk(KERN_ERR "%s: bsg interface failed to "
 410                        "initialize - register queue\n", dev->kobj.name);
 411                 goto out_cleanup_queue;
 412         }
 413
 414         return q;
 415 out_cleanup_queue:
 416         blk_cleanup_queue(q);
 417 out_queue:
 418         blk_mq_free_tag_set(set);
 419 out_tag_set:
 420         kfree(bset);
 421         return ERR_PTR(ret);
 422 }
 423 EXPORT_SYMBOL_GPL(bsg_setup_queue);