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 #include <scsi/sg.h>
  31
  32 #define uptr64(val) ((void __user *)(uintptr_t)(val))
  33
  34 static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
  35 {
  36         if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
  37             hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
  38                 return -EINVAL;
  39         if (!capable(CAP_SYS_RAWIO))
  40                 return -EPERM;
  41         return 0;
  42 }
  43
  44 static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
  45                 fmode_t mode)
  46 {
  47         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
  48
  49         job->request_len = hdr->request_len;
  50         job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
  51         if (IS_ERR(job->request))
  52                 return PTR_ERR(job->request);
  53         return 0;
  54 }
  55
  56 static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
  57 {
  58         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
  59         int ret = 0;
  60
  61         /*
  62          * The assignments below don't make much sense, but are kept for
  63          * bug by bug backwards compatibility:
  64          */
  65         hdr->device_status = job->result & 0xff;
  66         hdr->transport_status = host_byte(job->result);
  67         hdr->driver_status = driver_byte(job->result);
  68         hdr->info = 0;
  69         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
  70                 hdr->info |= SG_INFO_CHECK;
  71         hdr->response_len = 0;
  72
  73         if (job->result < 0) {
  74                 /* we're only returning the result field in the reply */
  75                 job->reply_len = sizeof(u32);
  76                 ret = job->result;
  77         }
  78
  79         if (job->reply_len && hdr->response) {
  80                 int len = min(hdr->max_response_len, job->reply_len);
  81
  82                 if (copy_to_user(uptr64(hdr->response), job->reply, len))
  83                         ret = -EFAULT;
  84                 else
  85                         hdr->response_len = len;
  86         }
  87
  88         /* we assume all request payload was transferred, residual == 0 */
  89         hdr->dout_resid = 0;
  90
  91         if (rq->next_rq) {
  92                 unsigned int rsp_len = job->reply_payload.payload_len;
  93
  94                 if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
  95                         hdr->din_resid = 0;
  96                 else
  97                         hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
  98         } else {
  99                 hdr->din_resid = 0;
 100         }
 101
 102         return ret;
 103 }
 104
 105 static void bsg_transport_free_rq(struct request *rq)
 106 {
 107         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 108
 109         kfree(job->request);
 110 }
 111
 112 static const struct bsg_ops bsg_transport_ops = {
 113         .check_proto            = bsg_transport_check_proto,
 114         .fill_hdr               = bsg_transport_fill_hdr,
 115         .complete_rq            = bsg_transport_complete_rq,
 116         .free_rq                = bsg_transport_free_rq,
 117 };
 118
 119 /**
 120  * bsg_teardown_job - routine to teardown a bsg job
 121  * @kref: kref inside bsg_job that is to be torn down
 122  */
 123 static void bsg_teardown_job(struct kref *kref)
 124 {
 125         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
 126         struct request *rq = blk_mq_rq_from_pdu(job);
 127
 128         put_device(job->dev);   /* release reference for the request */
 129
 130         kfree(job->request_payload.sg_list);
 131         kfree(job->reply_payload.sg_list);
 132
 133         blk_end_request_all(rq, BLK_STS_OK);
 134 }
 135
 136 void bsg_job_put(struct bsg_job *job)
 137 {
 138         kref_put(&job->kref, bsg_teardown_job);
 139 }
 140 EXPORT_SYMBOL_GPL(bsg_job_put);
 141
 142 int bsg_job_get(struct bsg_job *job)
 143 {
 144         return kref_get_unless_zero(&job->kref);
 145 }
 146 EXPORT_SYMBOL_GPL(bsg_job_get);
 147
 148 /**
 149  * bsg_job_done - completion routine for bsg requests
 150  * @job: bsg_job that is complete
 151  * @result: job reply result
 152  * @reply_payload_rcv_len: length of payload recvd
 153  *
 154  * The LLD should call this when the bsg job has completed.
 155  */
 156 void bsg_job_done(struct bsg_job *job, int result,
 157                   unsigned int reply_payload_rcv_len)
 158 {
 159         job->result = result;
 160         job->reply_payload_rcv_len = reply_payload_rcv_len;
 161         blk_complete_request(blk_mq_rq_from_pdu(job));
 162 }
 163 EXPORT_SYMBOL_GPL(bsg_job_done);
 164
 165 /**
 166  * bsg_softirq_done - softirq done routine for destroying the bsg requests
 167  * @rq: BSG request that holds the job to be destroyed
 168  */
 169 static void bsg_softirq_done(struct request *rq)
 170 {
 171         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 172
 173         bsg_job_put(job);
 174 }
 175
 176 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 177 {
 178         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 179
 180         BUG_ON(!req->nr_phys_segments);
 181
 182         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 183         if (!buf->sg_list)
 184                 return -ENOMEM;
 185         sg_init_table(buf->sg_list, req->nr_phys_segments);
 186         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 187         buf->payload_len = blk_rq_bytes(req);
 188         return 0;
 189 }
 190
 191 /**
 192  * bsg_prepare_job - create the bsg_job structure for the bsg request
 193  * @dev: device that is being sent the bsg request
 194  * @req: BSG request that needs a job structure
 195  */
 196 static bool bsg_prepare_job(struct device *dev, struct request *req)
 197 {
 198         struct request *rsp = req->next_rq;
 199         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 200         int ret;
 201
 202         job->timeout = req->timeout;
 203
 204         if (req->bio) {
 205                 ret = bsg_map_buffer(&job->request_payload, req);
 206                 if (ret)
 207                         goto failjob_rls_job;
 208         }
 209         if (rsp && rsp->bio) {
 210                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 211                 if (ret)
 212                         goto failjob_rls_rqst_payload;
 213         }
 214         job->dev = dev;
 215         /* take a reference for the request */
 216         get_device(job->dev);
 217         kref_init(&job->kref);
 218         return true;
 219
 220 failjob_rls_rqst_payload:
 221         kfree(job->request_payload.sg_list);
 222 failjob_rls_job:
 223         job->result = -ENOMEM;
 224         return false;
 225 }
 226
 227 /**
 228  * bsg_request_fn - generic handler for bsg requests
 229  * @q: request queue to manage
 230  *
 231  * On error the create_bsg_job function should return a -Exyz error value
 232  * that will be set to ->result.
 233  *
 234  * Drivers/subsys should pass this to the queue init function.
 235  */
 236 static void bsg_request_fn(struct request_queue *q)
 237         __releases(q->queue_lock)
 238         __acquires(q->queue_lock)
 239 {
 240         struct device *dev = q->queuedata;
 241         struct request *req;
 242         int ret;
 243
 244         if (!get_device(dev))
 245                 return;
 246
 247         while (1) {
 248                 req = blk_fetch_request(q);
 249                 if (!req)
 250                         break;
 251                 spin_unlock_irq(q->queue_lock);
 252
 253                 if (!bsg_prepare_job(dev, req)) {
 254                         blk_end_request_all(req, BLK_STS_OK);
 255                         spin_lock_irq(q->queue_lock);
 256                         continue;
 257                 }
 258
 259                 ret = q->bsg_job_fn(blk_mq_rq_to_pdu(req));
 260                 spin_lock_irq(q->queue_lock);
 261                 if (ret)
 262                         break;
 263         }
 264
 265         spin_unlock_irq(q->queue_lock);
 266         put_device(dev);
 267         spin_lock_irq(q->queue_lock);
 268 }
 269
 270 /* called right after the request is allocated for the request_queue */
 271 static int bsg_init_rq(struct request_queue *q, struct request *req, gfp_t gfp)
 272 {
 273         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 274
 275         job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, gfp);
 276         if (!job->reply)
 277                 return -ENOMEM;
 278         return 0;
 279 }
 280
 281 /* called right before the request is given to the request_queue user */
 282 static void bsg_initialize_rq(struct request *req)
 283 {
 284         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 285         void *reply = job->reply;
 286
 287         memset(job, 0, sizeof(*job));
 288         job->reply = reply;
 289         job->reply_len = SCSI_SENSE_BUFFERSIZE;
 290         job->dd_data = job + 1;
 291 }
 292
 293 static void bsg_exit_rq(struct request_queue *q, struct request *req)
 294 {
 295         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 296
 297         kfree(job->reply);
 298 }
 299
 300 /**
 301  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 302  * @dev: device to attach bsg device to
 303  * @name: device to give bsg device
 304  * @job_fn: bsg job handler
 305  * @dd_job_size: size of LLD data needed for each job
 306  */
 307 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 308                 bsg_job_fn *job_fn, int dd_job_size)
 309 {
 310         struct request_queue *q;
 311         int ret;
 312
 313         q = blk_alloc_queue(GFP_KERNEL);
 314         if (!q)
 315                 return ERR_PTR(-ENOMEM);
 316         q->cmd_size = sizeof(struct bsg_job) + dd_job_size;
 317         q->init_rq_fn = bsg_init_rq;
 318         q->exit_rq_fn = bsg_exit_rq;
 319         q->initialize_rq_fn = bsg_initialize_rq;
 320         q->request_fn = bsg_request_fn;
 321
 322         ret = blk_init_allocated_queue(q);
 323         if (ret)
 324                 goto out_cleanup_queue;
 325
 326         q->queuedata = dev;
 327         q->bsg_job_fn = job_fn;
 328         blk_queue_flag_set(QUEUE_FLAG_BIDI, q);
 329         blk_queue_softirq_done(q, bsg_softirq_done);
 330         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 331
 332         ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
 333         if (ret) {
 334                 printk(KERN_ERR "%s: bsg interface failed to "
 335                        "initialize - register queue\n", dev->kobj.name);
 336                 goto out_cleanup_queue;
 337         }
 338
 339         return q;
 340 out_cleanup_queue:
 341         blk_cleanup_queue(q);
 342         return ERR_PTR(ret);
 343 }
 344 EXPORT_SYMBOL_GPL(bsg_setup_queue);