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