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Linux/block/bsg-lib.c

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  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);
424 

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