Merge tag 'ntb-4.6' of git://github.com/jonmason/ntb
[linux-2.6-microblaze.git] / drivers / scsi / scsi_lib.c
1 /*
2  * Copyright (C) 1999 Eric Youngdale
3  * Copyright (C) 2014 Christoph Hellwig
4  *
5  *  SCSI queueing library.
6  *      Initial versions: Eric Youngdale (eric@andante.org).
7  *                        Based upon conversations with large numbers
8  *                        of people at Linux Expo.
9  */
10
11 #include <linux/bio.h>
12 #include <linux/bitops.h>
13 #include <linux/blkdev.h>
14 #include <linux/completion.h>
15 #include <linux/kernel.h>
16 #include <linux/export.h>
17 #include <linux/mempool.h>
18 #include <linux/slab.h>
19 #include <linux/init.h>
20 #include <linux/pci.h>
21 #include <linux/delay.h>
22 #include <linux/hardirq.h>
23 #include <linux/scatterlist.h>
24 #include <linux/blk-mq.h>
25 #include <linux/ratelimit.h>
26 #include <asm/unaligned.h>
27
28 #include <scsi/scsi.h>
29 #include <scsi/scsi_cmnd.h>
30 #include <scsi/scsi_dbg.h>
31 #include <scsi/scsi_device.h>
32 #include <scsi/scsi_driver.h>
33 #include <scsi/scsi_eh.h>
34 #include <scsi/scsi_host.h>
35 #include <scsi/scsi_dh.h>
36
37 #include <trace/events/scsi.h>
38
39 #include "scsi_priv.h"
40 #include "scsi_logging.h"
41
42
43 #define SG_MEMPOOL_NR           ARRAY_SIZE(scsi_sg_pools)
44 #define SG_MEMPOOL_SIZE         2
45
46 struct scsi_host_sg_pool {
47         size_t          size;
48         char            *name;
49         struct kmem_cache       *slab;
50         mempool_t       *pool;
51 };
52
53 #define SP(x) { .size = x, "sgpool-" __stringify(x) }
54 #if (SCSI_MAX_SG_SEGMENTS < 32)
55 #error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
56 #endif
57 static struct scsi_host_sg_pool scsi_sg_pools[] = {
58         SP(8),
59         SP(16),
60 #if (SCSI_MAX_SG_SEGMENTS > 32)
61         SP(32),
62 #if (SCSI_MAX_SG_SEGMENTS > 64)
63         SP(64),
64 #if (SCSI_MAX_SG_SEGMENTS > 128)
65         SP(128),
66 #if (SCSI_MAX_SG_SEGMENTS > 256)
67 #error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
68 #endif
69 #endif
70 #endif
71 #endif
72         SP(SCSI_MAX_SG_SEGMENTS)
73 };
74 #undef SP
75
76 struct kmem_cache *scsi_sdb_cache;
77
78 /*
79  * When to reinvoke queueing after a resource shortage. It's 3 msecs to
80  * not change behaviour from the previous unplug mechanism, experimentation
81  * may prove this needs changing.
82  */
83 #define SCSI_QUEUE_DELAY        3
84
85 static void
86 scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
87 {
88         struct Scsi_Host *host = cmd->device->host;
89         struct scsi_device *device = cmd->device;
90         struct scsi_target *starget = scsi_target(device);
91
92         /*
93          * Set the appropriate busy bit for the device/host.
94          *
95          * If the host/device isn't busy, assume that something actually
96          * completed, and that we should be able to queue a command now.
97          *
98          * Note that the prior mid-layer assumption that any host could
99          * always queue at least one command is now broken.  The mid-layer
100          * will implement a user specifiable stall (see
101          * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
102          * if a command is requeued with no other commands outstanding
103          * either for the device or for the host.
104          */
105         switch (reason) {
106         case SCSI_MLQUEUE_HOST_BUSY:
107                 atomic_set(&host->host_blocked, host->max_host_blocked);
108                 break;
109         case SCSI_MLQUEUE_DEVICE_BUSY:
110         case SCSI_MLQUEUE_EH_RETRY:
111                 atomic_set(&device->device_blocked,
112                            device->max_device_blocked);
113                 break;
114         case SCSI_MLQUEUE_TARGET_BUSY:
115                 atomic_set(&starget->target_blocked,
116                            starget->max_target_blocked);
117                 break;
118         }
119 }
120
121 static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
122 {
123         struct scsi_device *sdev = cmd->device;
124         struct request_queue *q = cmd->request->q;
125
126         blk_mq_requeue_request(cmd->request);
127         blk_mq_kick_requeue_list(q);
128         put_device(&sdev->sdev_gendev);
129 }
130
131 /**
132  * __scsi_queue_insert - private queue insertion
133  * @cmd: The SCSI command being requeued
134  * @reason:  The reason for the requeue
135  * @unbusy: Whether the queue should be unbusied
136  *
137  * This is a private queue insertion.  The public interface
138  * scsi_queue_insert() always assumes the queue should be unbusied
139  * because it's always called before the completion.  This function is
140  * for a requeue after completion, which should only occur in this
141  * file.
142  */
143 static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
144 {
145         struct scsi_device *device = cmd->device;
146         struct request_queue *q = device->request_queue;
147         unsigned long flags;
148
149         SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd,
150                 "Inserting command %p into mlqueue\n", cmd));
151
152         scsi_set_blocked(cmd, reason);
153
154         /*
155          * Decrement the counters, since these commands are no longer
156          * active on the host/device.
157          */
158         if (unbusy)
159                 scsi_device_unbusy(device);
160
161         /*
162          * Requeue this command.  It will go before all other commands
163          * that are already in the queue. Schedule requeue work under
164          * lock such that the kblockd_schedule_work() call happens
165          * before blk_cleanup_queue() finishes.
166          */
167         cmd->result = 0;
168         if (q->mq_ops) {
169                 scsi_mq_requeue_cmd(cmd);
170                 return;
171         }
172         spin_lock_irqsave(q->queue_lock, flags);
173         blk_requeue_request(q, cmd->request);
174         kblockd_schedule_work(&device->requeue_work);
175         spin_unlock_irqrestore(q->queue_lock, flags);
176 }
177
178 /*
179  * Function:    scsi_queue_insert()
180  *
181  * Purpose:     Insert a command in the midlevel queue.
182  *
183  * Arguments:   cmd    - command that we are adding to queue.
184  *              reason - why we are inserting command to queue.
185  *
186  * Lock status: Assumed that lock is not held upon entry.
187  *
188  * Returns:     Nothing.
189  *
190  * Notes:       We do this for one of two cases.  Either the host is busy
191  *              and it cannot accept any more commands for the time being,
192  *              or the device returned QUEUE_FULL and can accept no more
193  *              commands.
194  * Notes:       This could be called either from an interrupt context or a
195  *              normal process context.
196  */
197 void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
198 {
199         __scsi_queue_insert(cmd, reason, 1);
200 }
201 /**
202  * scsi_execute - insert request and wait for the result
203  * @sdev:       scsi device
204  * @cmd:        scsi command
205  * @data_direction: data direction
206  * @buffer:     data buffer
207  * @bufflen:    len of buffer
208  * @sense:      optional sense buffer
209  * @timeout:    request timeout in seconds
210  * @retries:    number of times to retry request
211  * @flags:      or into request flags;
212  * @resid:      optional residual length
213  *
214  * returns the req->errors value which is the scsi_cmnd result
215  * field.
216  */
217 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
218                  int data_direction, void *buffer, unsigned bufflen,
219                  unsigned char *sense, int timeout, int retries, u64 flags,
220                  int *resid)
221 {
222         struct request *req;
223         int write = (data_direction == DMA_TO_DEVICE);
224         int ret = DRIVER_ERROR << 24;
225
226         req = blk_get_request(sdev->request_queue, write, __GFP_RECLAIM);
227         if (IS_ERR(req))
228                 return ret;
229         blk_rq_set_block_pc(req);
230
231         if (bufflen &&  blk_rq_map_kern(sdev->request_queue, req,
232                                         buffer, bufflen, __GFP_RECLAIM))
233                 goto out;
234
235         req->cmd_len = COMMAND_SIZE(cmd[0]);
236         memcpy(req->cmd, cmd, req->cmd_len);
237         req->sense = sense;
238         req->sense_len = 0;
239         req->retries = retries;
240         req->timeout = timeout;
241         req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
242
243         /*
244          * head injection *required* here otherwise quiesce won't work
245          */
246         blk_execute_rq(req->q, NULL, req, 1);
247
248         /*
249          * Some devices (USB mass-storage in particular) may transfer
250          * garbage data together with a residue indicating that the data
251          * is invalid.  Prevent the garbage from being misinterpreted
252          * and prevent security leaks by zeroing out the excess data.
253          */
254         if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
255                 memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
256
257         if (resid)
258                 *resid = req->resid_len;
259         ret = req->errors;
260  out:
261         blk_put_request(req);
262
263         return ret;
264 }
265 EXPORT_SYMBOL(scsi_execute);
266
267 int scsi_execute_req_flags(struct scsi_device *sdev, const unsigned char *cmd,
268                      int data_direction, void *buffer, unsigned bufflen,
269                      struct scsi_sense_hdr *sshdr, int timeout, int retries,
270                      int *resid, u64 flags)
271 {
272         char *sense = NULL;
273         int result;
274         
275         if (sshdr) {
276                 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
277                 if (!sense)
278                         return DRIVER_ERROR << 24;
279         }
280         result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
281                               sense, timeout, retries, flags, resid);
282         if (sshdr)
283                 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
284
285         kfree(sense);
286         return result;
287 }
288 EXPORT_SYMBOL(scsi_execute_req_flags);
289
290 /*
291  * Function:    scsi_init_cmd_errh()
292  *
293  * Purpose:     Initialize cmd fields related to error handling.
294  *
295  * Arguments:   cmd     - command that is ready to be queued.
296  *
297  * Notes:       This function has the job of initializing a number of
298  *              fields related to error handling.   Typically this will
299  *              be called once for each command, as required.
300  */
301 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
302 {
303         cmd->serial_number = 0;
304         scsi_set_resid(cmd, 0);
305         memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
306         if (cmd->cmd_len == 0)
307                 cmd->cmd_len = scsi_command_size(cmd->cmnd);
308 }
309
310 void scsi_device_unbusy(struct scsi_device *sdev)
311 {
312         struct Scsi_Host *shost = sdev->host;
313         struct scsi_target *starget = scsi_target(sdev);
314         unsigned long flags;
315
316         atomic_dec(&shost->host_busy);
317         if (starget->can_queue > 0)
318                 atomic_dec(&starget->target_busy);
319
320         if (unlikely(scsi_host_in_recovery(shost) &&
321                      (shost->host_failed || shost->host_eh_scheduled))) {
322                 spin_lock_irqsave(shost->host_lock, flags);
323                 scsi_eh_wakeup(shost);
324                 spin_unlock_irqrestore(shost->host_lock, flags);
325         }
326
327         atomic_dec(&sdev->device_busy);
328 }
329
330 static void scsi_kick_queue(struct request_queue *q)
331 {
332         if (q->mq_ops)
333                 blk_mq_start_hw_queues(q);
334         else
335                 blk_run_queue(q);
336 }
337
338 /*
339  * Called for single_lun devices on IO completion. Clear starget_sdev_user,
340  * and call blk_run_queue for all the scsi_devices on the target -
341  * including current_sdev first.
342  *
343  * Called with *no* scsi locks held.
344  */
345 static void scsi_single_lun_run(struct scsi_device *current_sdev)
346 {
347         struct Scsi_Host *shost = current_sdev->host;
348         struct scsi_device *sdev, *tmp;
349         struct scsi_target *starget = scsi_target(current_sdev);
350         unsigned long flags;
351
352         spin_lock_irqsave(shost->host_lock, flags);
353         starget->starget_sdev_user = NULL;
354         spin_unlock_irqrestore(shost->host_lock, flags);
355
356         /*
357          * Call blk_run_queue for all LUNs on the target, starting with
358          * current_sdev. We race with others (to set starget_sdev_user),
359          * but in most cases, we will be first. Ideally, each LU on the
360          * target would get some limited time or requests on the target.
361          */
362         scsi_kick_queue(current_sdev->request_queue);
363
364         spin_lock_irqsave(shost->host_lock, flags);
365         if (starget->starget_sdev_user)
366                 goto out;
367         list_for_each_entry_safe(sdev, tmp, &starget->devices,
368                         same_target_siblings) {
369                 if (sdev == current_sdev)
370                         continue;
371                 if (scsi_device_get(sdev))
372                         continue;
373
374                 spin_unlock_irqrestore(shost->host_lock, flags);
375                 scsi_kick_queue(sdev->request_queue);
376                 spin_lock_irqsave(shost->host_lock, flags);
377         
378                 scsi_device_put(sdev);
379         }
380  out:
381         spin_unlock_irqrestore(shost->host_lock, flags);
382 }
383
384 static inline bool scsi_device_is_busy(struct scsi_device *sdev)
385 {
386         if (atomic_read(&sdev->device_busy) >= sdev->queue_depth)
387                 return true;
388         if (atomic_read(&sdev->device_blocked) > 0)
389                 return true;
390         return false;
391 }
392
393 static inline bool scsi_target_is_busy(struct scsi_target *starget)
394 {
395         if (starget->can_queue > 0) {
396                 if (atomic_read(&starget->target_busy) >= starget->can_queue)
397                         return true;
398                 if (atomic_read(&starget->target_blocked) > 0)
399                         return true;
400         }
401         return false;
402 }
403
404 static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
405 {
406         if (shost->can_queue > 0 &&
407             atomic_read(&shost->host_busy) >= shost->can_queue)
408                 return true;
409         if (atomic_read(&shost->host_blocked) > 0)
410                 return true;
411         if (shost->host_self_blocked)
412                 return true;
413         return false;
414 }
415
416 static void scsi_starved_list_run(struct Scsi_Host *shost)
417 {
418         LIST_HEAD(starved_list);
419         struct scsi_device *sdev;
420         unsigned long flags;
421
422         spin_lock_irqsave(shost->host_lock, flags);
423         list_splice_init(&shost->starved_list, &starved_list);
424
425         while (!list_empty(&starved_list)) {
426                 struct request_queue *slq;
427
428                 /*
429                  * As long as shost is accepting commands and we have
430                  * starved queues, call blk_run_queue. scsi_request_fn
431                  * drops the queue_lock and can add us back to the
432                  * starved_list.
433                  *
434                  * host_lock protects the starved_list and starved_entry.
435                  * scsi_request_fn must get the host_lock before checking
436                  * or modifying starved_list or starved_entry.
437                  */
438                 if (scsi_host_is_busy(shost))
439                         break;
440
441                 sdev = list_entry(starved_list.next,
442                                   struct scsi_device, starved_entry);
443                 list_del_init(&sdev->starved_entry);
444                 if (scsi_target_is_busy(scsi_target(sdev))) {
445                         list_move_tail(&sdev->starved_entry,
446                                        &shost->starved_list);
447                         continue;
448                 }
449
450                 /*
451                  * Once we drop the host lock, a racing scsi_remove_device()
452                  * call may remove the sdev from the starved list and destroy
453                  * it and the queue.  Mitigate by taking a reference to the
454                  * queue and never touching the sdev again after we drop the
455                  * host lock.  Note: if __scsi_remove_device() invokes
456                  * blk_cleanup_queue() before the queue is run from this
457                  * function then blk_run_queue() will return immediately since
458                  * blk_cleanup_queue() marks the queue with QUEUE_FLAG_DYING.
459                  */
460                 slq = sdev->request_queue;
461                 if (!blk_get_queue(slq))
462                         continue;
463                 spin_unlock_irqrestore(shost->host_lock, flags);
464
465                 scsi_kick_queue(slq);
466                 blk_put_queue(slq);
467
468                 spin_lock_irqsave(shost->host_lock, flags);
469         }
470         /* put any unprocessed entries back */
471         list_splice(&starved_list, &shost->starved_list);
472         spin_unlock_irqrestore(shost->host_lock, flags);
473 }
474
475 /*
476  * Function:   scsi_run_queue()
477  *
478  * Purpose:    Select a proper request queue to serve next
479  *
480  * Arguments:  q       - last request's queue
481  *
482  * Returns:     Nothing
483  *
484  * Notes:      The previous command was completely finished, start
485  *             a new one if possible.
486  */
487 static void scsi_run_queue(struct request_queue *q)
488 {
489         struct scsi_device *sdev = q->queuedata;
490
491         if (scsi_target(sdev)->single_lun)
492                 scsi_single_lun_run(sdev);
493         if (!list_empty(&sdev->host->starved_list))
494                 scsi_starved_list_run(sdev->host);
495
496         if (q->mq_ops)
497                 blk_mq_start_stopped_hw_queues(q, false);
498         else
499                 blk_run_queue(q);
500 }
501
502 void scsi_requeue_run_queue(struct work_struct *work)
503 {
504         struct scsi_device *sdev;
505         struct request_queue *q;
506
507         sdev = container_of(work, struct scsi_device, requeue_work);
508         q = sdev->request_queue;
509         scsi_run_queue(q);
510 }
511
512 /*
513  * Function:    scsi_requeue_command()
514  *
515  * Purpose:     Handle post-processing of completed commands.
516  *
517  * Arguments:   q       - queue to operate on
518  *              cmd     - command that may need to be requeued.
519  *
520  * Returns:     Nothing
521  *
522  * Notes:       After command completion, there may be blocks left
523  *              over which weren't finished by the previous command
524  *              this can be for a number of reasons - the main one is
525  *              I/O errors in the middle of the request, in which case
526  *              we need to request the blocks that come after the bad
527  *              sector.
528  * Notes:       Upon return, cmd is a stale pointer.
529  */
530 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
531 {
532         struct scsi_device *sdev = cmd->device;
533         struct request *req = cmd->request;
534         unsigned long flags;
535
536         spin_lock_irqsave(q->queue_lock, flags);
537         blk_unprep_request(req);
538         req->special = NULL;
539         scsi_put_command(cmd);
540         blk_requeue_request(q, req);
541         spin_unlock_irqrestore(q->queue_lock, flags);
542
543         scsi_run_queue(q);
544
545         put_device(&sdev->sdev_gendev);
546 }
547
548 void scsi_run_host_queues(struct Scsi_Host *shost)
549 {
550         struct scsi_device *sdev;
551
552         shost_for_each_device(sdev, shost)
553                 scsi_run_queue(sdev->request_queue);
554 }
555
556 static inline unsigned int scsi_sgtable_index(unsigned short nents)
557 {
558         unsigned int index;
559
560         BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
561
562         if (nents <= 8)
563                 index = 0;
564         else
565                 index = get_count_order(nents) - 3;
566
567         return index;
568 }
569
570 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
571 {
572         struct scsi_host_sg_pool *sgp;
573
574         sgp = scsi_sg_pools + scsi_sgtable_index(nents);
575         mempool_free(sgl, sgp->pool);
576 }
577
578 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
579 {
580         struct scsi_host_sg_pool *sgp;
581
582         sgp = scsi_sg_pools + scsi_sgtable_index(nents);
583         return mempool_alloc(sgp->pool, gfp_mask);
584 }
585
586 static void scsi_free_sgtable(struct scsi_data_buffer *sdb, bool mq)
587 {
588         if (mq && sdb->table.orig_nents <= SCSI_MAX_SG_SEGMENTS)
589                 return;
590         __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, mq, scsi_sg_free);
591 }
592
593 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, bool mq)
594 {
595         struct scatterlist *first_chunk = NULL;
596         int ret;
597
598         BUG_ON(!nents);
599
600         if (mq) {
601                 if (nents <= SCSI_MAX_SG_SEGMENTS) {
602                         sdb->table.nents = sdb->table.orig_nents = nents;
603                         sg_init_table(sdb->table.sgl, nents);
604                         return 0;
605                 }
606                 first_chunk = sdb->table.sgl;
607         }
608
609         ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
610                                first_chunk, GFP_ATOMIC, scsi_sg_alloc);
611         if (unlikely(ret))
612                 scsi_free_sgtable(sdb, mq);
613         return ret;
614 }
615
616 static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
617 {
618         if (cmd->request->cmd_type == REQ_TYPE_FS) {
619                 struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
620
621                 if (drv->uninit_command)
622                         drv->uninit_command(cmd);
623         }
624 }
625
626 static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
627 {
628         if (cmd->sdb.table.nents)
629                 scsi_free_sgtable(&cmd->sdb, true);
630         if (cmd->request->next_rq && cmd->request->next_rq->special)
631                 scsi_free_sgtable(cmd->request->next_rq->special, true);
632         if (scsi_prot_sg_count(cmd))
633                 scsi_free_sgtable(cmd->prot_sdb, true);
634 }
635
636 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
637 {
638         struct scsi_device *sdev = cmd->device;
639         struct Scsi_Host *shost = sdev->host;
640         unsigned long flags;
641
642         scsi_mq_free_sgtables(cmd);
643         scsi_uninit_cmd(cmd);
644
645         if (shost->use_cmd_list) {
646                 BUG_ON(list_empty(&cmd->list));
647                 spin_lock_irqsave(&sdev->list_lock, flags);
648                 list_del_init(&cmd->list);
649                 spin_unlock_irqrestore(&sdev->list_lock, flags);
650         }
651 }
652
653 /*
654  * Function:    scsi_release_buffers()
655  *
656  * Purpose:     Free resources allocate for a scsi_command.
657  *
658  * Arguments:   cmd     - command that we are bailing.
659  *
660  * Lock status: Assumed that no lock is held upon entry.
661  *
662  * Returns:     Nothing
663  *
664  * Notes:       In the event that an upper level driver rejects a
665  *              command, we must release resources allocated during
666  *              the __init_io() function.  Primarily this would involve
667  *              the scatter-gather table.
668  */
669 static void scsi_release_buffers(struct scsi_cmnd *cmd)
670 {
671         if (cmd->sdb.table.nents)
672                 scsi_free_sgtable(&cmd->sdb, false);
673
674         memset(&cmd->sdb, 0, sizeof(cmd->sdb));
675
676         if (scsi_prot_sg_count(cmd))
677                 scsi_free_sgtable(cmd->prot_sdb, false);
678 }
679
680 static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
681 {
682         struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special;
683
684         scsi_free_sgtable(bidi_sdb, false);
685         kmem_cache_free(scsi_sdb_cache, bidi_sdb);
686         cmd->request->next_rq->special = NULL;
687 }
688
689 static bool scsi_end_request(struct request *req, int error,
690                 unsigned int bytes, unsigned int bidi_bytes)
691 {
692         struct scsi_cmnd *cmd = req->special;
693         struct scsi_device *sdev = cmd->device;
694         struct request_queue *q = sdev->request_queue;
695
696         if (blk_update_request(req, error, bytes))
697                 return true;
698
699         /* Bidi request must be completed as a whole */
700         if (unlikely(bidi_bytes) &&
701             blk_update_request(req->next_rq, error, bidi_bytes))
702                 return true;
703
704         if (blk_queue_add_random(q))
705                 add_disk_randomness(req->rq_disk);
706
707         if (req->mq_ctx) {
708                 /*
709                  * In the MQ case the command gets freed by __blk_mq_end_request,
710                  * so we have to do all cleanup that depends on it earlier.
711                  *
712                  * We also can't kick the queues from irq context, so we
713                  * will have to defer it to a workqueue.
714                  */
715                 scsi_mq_uninit_cmd(cmd);
716
717                 __blk_mq_end_request(req, error);
718
719                 if (scsi_target(sdev)->single_lun ||
720                     !list_empty(&sdev->host->starved_list))
721                         kblockd_schedule_work(&sdev->requeue_work);
722                 else
723                         blk_mq_start_stopped_hw_queues(q, true);
724         } else {
725                 unsigned long flags;
726
727                 if (bidi_bytes)
728                         scsi_release_bidi_buffers(cmd);
729
730                 spin_lock_irqsave(q->queue_lock, flags);
731                 blk_finish_request(req, error);
732                 spin_unlock_irqrestore(q->queue_lock, flags);
733
734                 scsi_release_buffers(cmd);
735
736                 scsi_put_command(cmd);
737                 scsi_run_queue(q);
738         }
739
740         put_device(&sdev->sdev_gendev);
741         return false;
742 }
743
744 /**
745  * __scsi_error_from_host_byte - translate SCSI error code into errno
746  * @cmd:        SCSI command (unused)
747  * @result:     scsi error code
748  *
749  * Translate SCSI error code into standard UNIX errno.
750  * Return values:
751  * -ENOLINK     temporary transport failure
752  * -EREMOTEIO   permanent target failure, do not retry
753  * -EBADE       permanent nexus failure, retry on other path
754  * -ENOSPC      No write space available
755  * -ENODATA     Medium error
756  * -EIO         unspecified I/O error
757  */
758 static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
759 {
760         int error = 0;
761
762         switch(host_byte(result)) {
763         case DID_TRANSPORT_FAILFAST:
764                 error = -ENOLINK;
765                 break;
766         case DID_TARGET_FAILURE:
767                 set_host_byte(cmd, DID_OK);
768                 error = -EREMOTEIO;
769                 break;
770         case DID_NEXUS_FAILURE:
771                 set_host_byte(cmd, DID_OK);
772                 error = -EBADE;
773                 break;
774         case DID_ALLOC_FAILURE:
775                 set_host_byte(cmd, DID_OK);
776                 error = -ENOSPC;
777                 break;
778         case DID_MEDIUM_ERROR:
779                 set_host_byte(cmd, DID_OK);
780                 error = -ENODATA;
781                 break;
782         default:
783                 error = -EIO;
784                 break;
785         }
786
787         return error;
788 }
789
790 /*
791  * Function:    scsi_io_completion()
792  *
793  * Purpose:     Completion processing for block device I/O requests.
794  *
795  * Arguments:   cmd   - command that is finished.
796  *
797  * Lock status: Assumed that no lock is held upon entry.
798  *
799  * Returns:     Nothing
800  *
801  * Notes:       We will finish off the specified number of sectors.  If we
802  *              are done, the command block will be released and the queue
803  *              function will be goosed.  If we are not done then we have to
804  *              figure out what to do next:
805  *
806  *              a) We can call scsi_requeue_command().  The request
807  *                 will be unprepared and put back on the queue.  Then
808  *                 a new command will be created for it.  This should
809  *                 be used if we made forward progress, or if we want
810  *                 to switch from READ(10) to READ(6) for example.
811  *
812  *              b) We can call __scsi_queue_insert().  The request will
813  *                 be put back on the queue and retried using the same
814  *                 command as before, possibly after a delay.
815  *
816  *              c) We can call scsi_end_request() with -EIO to fail
817  *                 the remainder of the request.
818  */
819 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
820 {
821         int result = cmd->result;
822         struct request_queue *q = cmd->device->request_queue;
823         struct request *req = cmd->request;
824         int error = 0;
825         struct scsi_sense_hdr sshdr;
826         bool sense_valid = false;
827         int sense_deferred = 0, level = 0;
828         enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
829               ACTION_DELAYED_RETRY} action;
830         unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
831
832         if (result) {
833                 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
834                 if (sense_valid)
835                         sense_deferred = scsi_sense_is_deferred(&sshdr);
836         }
837
838         if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
839                 if (result) {
840                         if (sense_valid && req->sense) {
841                                 /*
842                                  * SG_IO wants current and deferred errors
843                                  */
844                                 int len = 8 + cmd->sense_buffer[7];
845
846                                 if (len > SCSI_SENSE_BUFFERSIZE)
847                                         len = SCSI_SENSE_BUFFERSIZE;
848                                 memcpy(req->sense, cmd->sense_buffer,  len);
849                                 req->sense_len = len;
850                         }
851                         if (!sense_deferred)
852                                 error = __scsi_error_from_host_byte(cmd, result);
853                 }
854                 /*
855                  * __scsi_error_from_host_byte may have reset the host_byte
856                  */
857                 req->errors = cmd->result;
858
859                 req->resid_len = scsi_get_resid(cmd);
860
861                 if (scsi_bidi_cmnd(cmd)) {
862                         /*
863                          * Bidi commands Must be complete as a whole,
864                          * both sides at once.
865                          */
866                         req->next_rq->resid_len = scsi_in(cmd)->resid;
867                         if (scsi_end_request(req, 0, blk_rq_bytes(req),
868                                         blk_rq_bytes(req->next_rq)))
869                                 BUG();
870                         return;
871                 }
872         } else if (blk_rq_bytes(req) == 0 && result && !sense_deferred) {
873                 /*
874                  * Certain non BLOCK_PC requests are commands that don't
875                  * actually transfer anything (FLUSH), so cannot use
876                  * good_bytes != blk_rq_bytes(req) as the signal for an error.
877                  * This sets the error explicitly for the problem case.
878                  */
879                 error = __scsi_error_from_host_byte(cmd, result);
880         }
881
882         /* no bidi support for !REQ_TYPE_BLOCK_PC yet */
883         BUG_ON(blk_bidi_rq(req));
884
885         /*
886          * Next deal with any sectors which we were able to correctly
887          * handle.
888          */
889         SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
890                 "%u sectors total, %d bytes done.\n",
891                 blk_rq_sectors(req), good_bytes));
892
893         /*
894          * Recovered errors need reporting, but they're always treated
895          * as success, so fiddle the result code here.  For BLOCK_PC
896          * we already took a copy of the original into rq->errors which
897          * is what gets returned to the user
898          */
899         if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
900                 /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
901                  * print since caller wants ATA registers. Only occurs on
902                  * SCSI ATA PASS_THROUGH commands when CK_COND=1
903                  */
904                 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
905                         ;
906                 else if (!(req->cmd_flags & REQ_QUIET))
907                         scsi_print_sense(cmd);
908                 result = 0;
909                 /* BLOCK_PC may have set error */
910                 error = 0;
911         }
912
913         /*
914          * If we finished all bytes in the request we are done now.
915          */
916         if (!scsi_end_request(req, error, good_bytes, 0))
917                 return;
918
919         /*
920          * Kill remainder if no retrys.
921          */
922         if (error && scsi_noretry_cmd(cmd)) {
923                 if (scsi_end_request(req, error, blk_rq_bytes(req), 0))
924                         BUG();
925                 return;
926         }
927
928         /*
929          * If there had been no error, but we have leftover bytes in the
930          * requeues just queue the command up again.
931          */
932         if (result == 0)
933                 goto requeue;
934
935         error = __scsi_error_from_host_byte(cmd, result);
936
937         if (host_byte(result) == DID_RESET) {
938                 /* Third party bus reset or reset for error recovery
939                  * reasons.  Just retry the command and see what
940                  * happens.
941                  */
942                 action = ACTION_RETRY;
943         } else if (sense_valid && !sense_deferred) {
944                 switch (sshdr.sense_key) {
945                 case UNIT_ATTENTION:
946                         if (cmd->device->removable) {
947                                 /* Detected disc change.  Set a bit
948                                  * and quietly refuse further access.
949                                  */
950                                 cmd->device->changed = 1;
951                                 action = ACTION_FAIL;
952                         } else {
953                                 /* Must have been a power glitch, or a
954                                  * bus reset.  Could not have been a
955                                  * media change, so we just retry the
956                                  * command and see what happens.
957                                  */
958                                 action = ACTION_RETRY;
959                         }
960                         break;
961                 case ILLEGAL_REQUEST:
962                         /* If we had an ILLEGAL REQUEST returned, then
963                          * we may have performed an unsupported
964                          * command.  The only thing this should be
965                          * would be a ten byte read where only a six
966                          * byte read was supported.  Also, on a system
967                          * where READ CAPACITY failed, we may have
968                          * read past the end of the disk.
969                          */
970                         if ((cmd->device->use_10_for_rw &&
971                             sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
972                             (cmd->cmnd[0] == READ_10 ||
973                              cmd->cmnd[0] == WRITE_10)) {
974                                 /* This will issue a new 6-byte command. */
975                                 cmd->device->use_10_for_rw = 0;
976                                 action = ACTION_REPREP;
977                         } else if (sshdr.asc == 0x10) /* DIX */ {
978                                 action = ACTION_FAIL;
979                                 error = -EILSEQ;
980                         /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
981                         } else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
982                                 action = ACTION_FAIL;
983                                 error = -EREMOTEIO;
984                         } else
985                                 action = ACTION_FAIL;
986                         break;
987                 case ABORTED_COMMAND:
988                         action = ACTION_FAIL;
989                         if (sshdr.asc == 0x10) /* DIF */
990                                 error = -EILSEQ;
991                         break;
992                 case NOT_READY:
993                         /* If the device is in the process of becoming
994                          * ready, or has a temporary blockage, retry.
995                          */
996                         if (sshdr.asc == 0x04) {
997                                 switch (sshdr.ascq) {
998                                 case 0x01: /* becoming ready */
999                                 case 0x04: /* format in progress */
1000                                 case 0x05: /* rebuild in progress */
1001                                 case 0x06: /* recalculation in progress */
1002                                 case 0x07: /* operation in progress */
1003                                 case 0x08: /* Long write in progress */
1004                                 case 0x09: /* self test in progress */
1005                                 case 0x14: /* space allocation in progress */
1006                                         action = ACTION_DELAYED_RETRY;
1007                                         break;
1008                                 default:
1009                                         action = ACTION_FAIL;
1010                                         break;
1011                                 }
1012                         } else
1013                                 action = ACTION_FAIL;
1014                         break;
1015                 case VOLUME_OVERFLOW:
1016                         /* See SSC3rXX or current. */
1017                         action = ACTION_FAIL;
1018                         break;
1019                 default:
1020                         action = ACTION_FAIL;
1021                         break;
1022                 }
1023         } else
1024                 action = ACTION_FAIL;
1025
1026         if (action != ACTION_FAIL &&
1027             time_before(cmd->jiffies_at_alloc + wait_for, jiffies))
1028                 action = ACTION_FAIL;
1029
1030         switch (action) {
1031         case ACTION_FAIL:
1032                 /* Give up and fail the remainder of the request */
1033                 if (!(req->cmd_flags & REQ_QUIET)) {
1034                         static DEFINE_RATELIMIT_STATE(_rs,
1035                                         DEFAULT_RATELIMIT_INTERVAL,
1036                                         DEFAULT_RATELIMIT_BURST);
1037
1038                         if (unlikely(scsi_logging_level))
1039                                 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
1040                                                        SCSI_LOG_MLCOMPLETE_BITS);
1041
1042                         /*
1043                          * if logging is enabled the failure will be printed
1044                          * in scsi_log_completion(), so avoid duplicate messages
1045                          */
1046                         if (!level && __ratelimit(&_rs)) {
1047                                 scsi_print_result(cmd, NULL, FAILED);
1048                                 if (driver_byte(result) & DRIVER_SENSE)
1049                                         scsi_print_sense(cmd);
1050                                 scsi_print_command(cmd);
1051                         }
1052                 }
1053                 if (!scsi_end_request(req, error, blk_rq_err_bytes(req), 0))
1054                         return;
1055                 /*FALLTHRU*/
1056         case ACTION_REPREP:
1057         requeue:
1058                 /* Unprep the request and put it back at the head of the queue.
1059                  * A new command will be prepared and issued.
1060                  */
1061                 if (q->mq_ops) {
1062                         cmd->request->cmd_flags &= ~REQ_DONTPREP;
1063                         scsi_mq_uninit_cmd(cmd);
1064                         scsi_mq_requeue_cmd(cmd);
1065                 } else {
1066                         scsi_release_buffers(cmd);
1067                         scsi_requeue_command(q, cmd);
1068                 }
1069                 break;
1070         case ACTION_RETRY:
1071                 /* Retry the same command immediately */
1072                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
1073                 break;
1074         case ACTION_DELAYED_RETRY:
1075                 /* Retry the same command after a delay */
1076                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
1077                 break;
1078         }
1079 }
1080
1081 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb)
1082 {
1083         int count;
1084
1085         /*
1086          * If sg table allocation fails, requeue request later.
1087          */
1088         if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
1089                                         req->mq_ctx != NULL)))
1090                 return BLKPREP_DEFER;
1091
1092         /* 
1093          * Next, walk the list, and fill in the addresses and sizes of
1094          * each segment.
1095          */
1096         count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1097         BUG_ON(count > sdb->table.nents);
1098         sdb->table.nents = count;
1099         sdb->length = blk_rq_bytes(req);
1100         return BLKPREP_OK;
1101 }
1102
1103 /*
1104  * Function:    scsi_init_io()
1105  *
1106  * Purpose:     SCSI I/O initialize function.
1107  *
1108  * Arguments:   cmd   - Command descriptor we wish to initialize
1109  *
1110  * Returns:     0 on success
1111  *              BLKPREP_DEFER if the failure is retryable
1112  *              BLKPREP_KILL if the failure is fatal
1113  */
1114 int scsi_init_io(struct scsi_cmnd *cmd)
1115 {
1116         struct scsi_device *sdev = cmd->device;
1117         struct request *rq = cmd->request;
1118         bool is_mq = (rq->mq_ctx != NULL);
1119         int error;
1120
1121         BUG_ON(!rq->nr_phys_segments);
1122
1123         error = scsi_init_sgtable(rq, &cmd->sdb);
1124         if (error)
1125                 goto err_exit;
1126
1127         if (blk_bidi_rq(rq)) {
1128                 if (!rq->q->mq_ops) {
1129                         struct scsi_data_buffer *bidi_sdb =
1130                                 kmem_cache_zalloc(scsi_sdb_cache, GFP_ATOMIC);
1131                         if (!bidi_sdb) {
1132                                 error = BLKPREP_DEFER;
1133                                 goto err_exit;
1134                         }
1135
1136                         rq->next_rq->special = bidi_sdb;
1137                 }
1138
1139                 error = scsi_init_sgtable(rq->next_rq, rq->next_rq->special);
1140                 if (error)
1141                         goto err_exit;
1142         }
1143
1144         if (blk_integrity_rq(rq)) {
1145                 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1146                 int ivecs, count;
1147
1148                 if (prot_sdb == NULL) {
1149                         /*
1150                          * This can happen if someone (e.g. multipath)
1151                          * queues a command to a device on an adapter
1152                          * that does not support DIX.
1153                          */
1154                         WARN_ON_ONCE(1);
1155                         error = BLKPREP_KILL;
1156                         goto err_exit;
1157                 }
1158
1159                 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1160
1161                 if (scsi_alloc_sgtable(prot_sdb, ivecs, is_mq)) {
1162                         error = BLKPREP_DEFER;
1163                         goto err_exit;
1164                 }
1165
1166                 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1167                                                 prot_sdb->table.sgl);
1168                 BUG_ON(unlikely(count > ivecs));
1169                 BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1170
1171                 cmd->prot_sdb = prot_sdb;
1172                 cmd->prot_sdb->table.nents = count;
1173         }
1174
1175         return BLKPREP_OK;
1176 err_exit:
1177         if (is_mq) {
1178                 scsi_mq_free_sgtables(cmd);
1179         } else {
1180                 scsi_release_buffers(cmd);
1181                 cmd->request->special = NULL;
1182                 scsi_put_command(cmd);
1183                 put_device(&sdev->sdev_gendev);
1184         }
1185         return error;
1186 }
1187 EXPORT_SYMBOL(scsi_init_io);
1188
1189 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1190                 struct request *req)
1191 {
1192         struct scsi_cmnd *cmd;
1193
1194         if (!req->special) {
1195                 /* Bail if we can't get a reference to the device */
1196                 if (!get_device(&sdev->sdev_gendev))
1197                         return NULL;
1198
1199                 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1200                 if (unlikely(!cmd)) {
1201                         put_device(&sdev->sdev_gendev);
1202                         return NULL;
1203                 }
1204                 req->special = cmd;
1205         } else {
1206                 cmd = req->special;
1207         }
1208
1209         /* pull a tag out of the request if we have one */
1210         cmd->tag = req->tag;
1211         cmd->request = req;
1212
1213         cmd->cmnd = req->cmd;
1214         cmd->prot_op = SCSI_PROT_NORMAL;
1215
1216         return cmd;
1217 }
1218
1219 static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1220 {
1221         struct scsi_cmnd *cmd = req->special;
1222
1223         /*
1224          * BLOCK_PC requests may transfer data, in which case they must
1225          * a bio attached to them.  Or they might contain a SCSI command
1226          * that does not transfer data, in which case they may optionally
1227          * submit a request without an attached bio.
1228          */
1229         if (req->bio) {
1230                 int ret = scsi_init_io(cmd);
1231                 if (unlikely(ret))
1232                         return ret;
1233         } else {
1234                 BUG_ON(blk_rq_bytes(req));
1235
1236                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1237         }
1238
1239         cmd->cmd_len = req->cmd_len;
1240         cmd->transfersize = blk_rq_bytes(req);
1241         cmd->allowed = req->retries;
1242         return BLKPREP_OK;
1243 }
1244
1245 /*
1246  * Setup a REQ_TYPE_FS command.  These are simple request from filesystems
1247  * that still need to be translated to SCSI CDBs from the ULD.
1248  */
1249 static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1250 {
1251         struct scsi_cmnd *cmd = req->special;
1252
1253         if (unlikely(sdev->handler && sdev->handler->prep_fn)) {
1254                 int ret = sdev->handler->prep_fn(sdev, req);
1255                 if (ret != BLKPREP_OK)
1256                         return ret;
1257         }
1258
1259         memset(cmd->cmnd, 0, BLK_MAX_CDB);
1260         return scsi_cmd_to_driver(cmd)->init_command(cmd);
1261 }
1262
1263 static int scsi_setup_cmnd(struct scsi_device *sdev, struct request *req)
1264 {
1265         struct scsi_cmnd *cmd = req->special;
1266
1267         if (!blk_rq_bytes(req))
1268                 cmd->sc_data_direction = DMA_NONE;
1269         else if (rq_data_dir(req) == WRITE)
1270                 cmd->sc_data_direction = DMA_TO_DEVICE;
1271         else
1272                 cmd->sc_data_direction = DMA_FROM_DEVICE;
1273
1274         switch (req->cmd_type) {
1275         case REQ_TYPE_FS:
1276                 return scsi_setup_fs_cmnd(sdev, req);
1277         case REQ_TYPE_BLOCK_PC:
1278                 return scsi_setup_blk_pc_cmnd(sdev, req);
1279         default:
1280                 return BLKPREP_KILL;
1281         }
1282 }
1283
1284 static int
1285 scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1286 {
1287         int ret = BLKPREP_OK;
1288
1289         /*
1290          * If the device is not in running state we will reject some
1291          * or all commands.
1292          */
1293         if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1294                 switch (sdev->sdev_state) {
1295                 case SDEV_OFFLINE:
1296                 case SDEV_TRANSPORT_OFFLINE:
1297                         /*
1298                          * If the device is offline we refuse to process any
1299                          * commands.  The device must be brought online
1300                          * before trying any recovery commands.
1301                          */
1302                         sdev_printk(KERN_ERR, sdev,
1303                                     "rejecting I/O to offline device\n");
1304                         ret = BLKPREP_KILL;
1305                         break;
1306                 case SDEV_DEL:
1307                         /*
1308                          * If the device is fully deleted, we refuse to
1309                          * process any commands as well.
1310                          */
1311                         sdev_printk(KERN_ERR, sdev,
1312                                     "rejecting I/O to dead device\n");
1313                         ret = BLKPREP_KILL;
1314                         break;
1315                 case SDEV_BLOCK:
1316                 case SDEV_CREATED_BLOCK:
1317                         ret = BLKPREP_DEFER;
1318                         break;
1319                 case SDEV_QUIESCE:
1320                         /*
1321                          * If the devices is blocked we defer normal commands.
1322                          */
1323                         if (!(req->cmd_flags & REQ_PREEMPT))
1324                                 ret = BLKPREP_DEFER;
1325                         break;
1326                 default:
1327                         /*
1328                          * For any other not fully online state we only allow
1329                          * special commands.  In particular any user initiated
1330                          * command is not allowed.
1331                          */
1332                         if (!(req->cmd_flags & REQ_PREEMPT))
1333                                 ret = BLKPREP_KILL;
1334                         break;
1335                 }
1336         }
1337         return ret;
1338 }
1339
1340 static int
1341 scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1342 {
1343         struct scsi_device *sdev = q->queuedata;
1344
1345         switch (ret) {
1346         case BLKPREP_KILL:
1347         case BLKPREP_INVALID:
1348                 req->errors = DID_NO_CONNECT << 16;
1349                 /* release the command and kill it */
1350                 if (req->special) {
1351                         struct scsi_cmnd *cmd = req->special;
1352                         scsi_release_buffers(cmd);
1353                         scsi_put_command(cmd);
1354                         put_device(&sdev->sdev_gendev);
1355                         req->special = NULL;
1356                 }
1357                 break;
1358         case BLKPREP_DEFER:
1359                 /*
1360                  * If we defer, the blk_peek_request() returns NULL, but the
1361                  * queue must be restarted, so we schedule a callback to happen
1362                  * shortly.
1363                  */
1364                 if (atomic_read(&sdev->device_busy) == 0)
1365                         blk_delay_queue(q, SCSI_QUEUE_DELAY);
1366                 break;
1367         default:
1368                 req->cmd_flags |= REQ_DONTPREP;
1369         }
1370
1371         return ret;
1372 }
1373
1374 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1375 {
1376         struct scsi_device *sdev = q->queuedata;
1377         struct scsi_cmnd *cmd;
1378         int ret;
1379
1380         ret = scsi_prep_state_check(sdev, req);
1381         if (ret != BLKPREP_OK)
1382                 goto out;
1383
1384         cmd = scsi_get_cmd_from_req(sdev, req);
1385         if (unlikely(!cmd)) {
1386                 ret = BLKPREP_DEFER;
1387                 goto out;
1388         }
1389
1390         ret = scsi_setup_cmnd(sdev, req);
1391 out:
1392         return scsi_prep_return(q, req, ret);
1393 }
1394
1395 static void scsi_unprep_fn(struct request_queue *q, struct request *req)
1396 {
1397         scsi_uninit_cmd(req->special);
1398 }
1399
1400 /*
1401  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1402  * return 0.
1403  *
1404  * Called with the queue_lock held.
1405  */
1406 static inline int scsi_dev_queue_ready(struct request_queue *q,
1407                                   struct scsi_device *sdev)
1408 {
1409         unsigned int busy;
1410
1411         busy = atomic_inc_return(&sdev->device_busy) - 1;
1412         if (atomic_read(&sdev->device_blocked)) {
1413                 if (busy)
1414                         goto out_dec;
1415
1416                 /*
1417                  * unblock after device_blocked iterates to zero
1418                  */
1419                 if (atomic_dec_return(&sdev->device_blocked) > 0) {
1420                         /*
1421                          * For the MQ case we take care of this in the caller.
1422                          */
1423                         if (!q->mq_ops)
1424                                 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1425                         goto out_dec;
1426                 }
1427                 SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
1428                                    "unblocking device at zero depth\n"));
1429         }
1430
1431         if (busy >= sdev->queue_depth)
1432                 goto out_dec;
1433
1434         return 1;
1435 out_dec:
1436         atomic_dec(&sdev->device_busy);
1437         return 0;
1438 }
1439
1440 /*
1441  * scsi_target_queue_ready: checks if there we can send commands to target
1442  * @sdev: scsi device on starget to check.
1443  */
1444 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1445                                            struct scsi_device *sdev)
1446 {
1447         struct scsi_target *starget = scsi_target(sdev);
1448         unsigned int busy;
1449
1450         if (starget->single_lun) {
1451                 spin_lock_irq(shost->host_lock);
1452                 if (starget->starget_sdev_user &&
1453                     starget->starget_sdev_user != sdev) {
1454                         spin_unlock_irq(shost->host_lock);
1455                         return 0;
1456                 }
1457                 starget->starget_sdev_user = sdev;
1458                 spin_unlock_irq(shost->host_lock);
1459         }
1460
1461         if (starget->can_queue <= 0)
1462                 return 1;
1463
1464         busy = atomic_inc_return(&starget->target_busy) - 1;
1465         if (atomic_read(&starget->target_blocked) > 0) {
1466                 if (busy)
1467                         goto starved;
1468
1469                 /*
1470                  * unblock after target_blocked iterates to zero
1471                  */
1472                 if (atomic_dec_return(&starget->target_blocked) > 0)
1473                         goto out_dec;
1474
1475                 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1476                                  "unblocking target at zero depth\n"));
1477         }
1478
1479         if (busy >= starget->can_queue)
1480                 goto starved;
1481
1482         return 1;
1483
1484 starved:
1485         spin_lock_irq(shost->host_lock);
1486         list_move_tail(&sdev->starved_entry, &shost->starved_list);
1487         spin_unlock_irq(shost->host_lock);
1488 out_dec:
1489         if (starget->can_queue > 0)
1490                 atomic_dec(&starget->target_busy);
1491         return 0;
1492 }
1493
1494 /*
1495  * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1496  * return 0. We must end up running the queue again whenever 0 is
1497  * returned, else IO can hang.
1498  */
1499 static inline int scsi_host_queue_ready(struct request_queue *q,
1500                                    struct Scsi_Host *shost,
1501                                    struct scsi_device *sdev)
1502 {
1503         unsigned int busy;
1504
1505         if (scsi_host_in_recovery(shost))
1506                 return 0;
1507
1508         busy = atomic_inc_return(&shost->host_busy) - 1;
1509         if (atomic_read(&shost->host_blocked) > 0) {
1510                 if (busy)
1511                         goto starved;
1512
1513                 /*
1514                  * unblock after host_blocked iterates to zero
1515                  */
1516                 if (atomic_dec_return(&shost->host_blocked) > 0)
1517                         goto out_dec;
1518
1519                 SCSI_LOG_MLQUEUE(3,
1520                         shost_printk(KERN_INFO, shost,
1521                                      "unblocking host at zero depth\n"));
1522         }
1523
1524         if (shost->can_queue > 0 && busy >= shost->can_queue)
1525                 goto starved;
1526         if (shost->host_self_blocked)
1527                 goto starved;
1528
1529         /* We're OK to process the command, so we can't be starved */
1530         if (!list_empty(&sdev->starved_entry)) {
1531                 spin_lock_irq(shost->host_lock);
1532                 if (!list_empty(&sdev->starved_entry))
1533                         list_del_init(&sdev->starved_entry);
1534                 spin_unlock_irq(shost->host_lock);
1535         }
1536
1537         return 1;
1538
1539 starved:
1540         spin_lock_irq(shost->host_lock);
1541         if (list_empty(&sdev->starved_entry))
1542                 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1543         spin_unlock_irq(shost->host_lock);
1544 out_dec:
1545         atomic_dec(&shost->host_busy);
1546         return 0;
1547 }
1548
1549 /*
1550  * Busy state exporting function for request stacking drivers.
1551  *
1552  * For efficiency, no lock is taken to check the busy state of
1553  * shost/starget/sdev, since the returned value is not guaranteed and
1554  * may be changed after request stacking drivers call the function,
1555  * regardless of taking lock or not.
1556  *
1557  * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1558  * needs to return 'not busy'. Otherwise, request stacking drivers
1559  * may hold requests forever.
1560  */
1561 static int scsi_lld_busy(struct request_queue *q)
1562 {
1563         struct scsi_device *sdev = q->queuedata;
1564         struct Scsi_Host *shost;
1565
1566         if (blk_queue_dying(q))
1567                 return 0;
1568
1569         shost = sdev->host;
1570
1571         /*
1572          * Ignore host/starget busy state.
1573          * Since block layer does not have a concept of fairness across
1574          * multiple queues, congestion of host/starget needs to be handled
1575          * in SCSI layer.
1576          */
1577         if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1578                 return 1;
1579
1580         return 0;
1581 }
1582
1583 /*
1584  * Kill a request for a dead device
1585  */
1586 static void scsi_kill_request(struct request *req, struct request_queue *q)
1587 {
1588         struct scsi_cmnd *cmd = req->special;
1589         struct scsi_device *sdev;
1590         struct scsi_target *starget;
1591         struct Scsi_Host *shost;
1592
1593         blk_start_request(req);
1594
1595         scmd_printk(KERN_INFO, cmd, "killing request\n");
1596
1597         sdev = cmd->device;
1598         starget = scsi_target(sdev);
1599         shost = sdev->host;
1600         scsi_init_cmd_errh(cmd);
1601         cmd->result = DID_NO_CONNECT << 16;
1602         atomic_inc(&cmd->device->iorequest_cnt);
1603
1604         /*
1605          * SCSI request completion path will do scsi_device_unbusy(),
1606          * bump busy counts.  To bump the counters, we need to dance
1607          * with the locks as normal issue path does.
1608          */
1609         atomic_inc(&sdev->device_busy);
1610         atomic_inc(&shost->host_busy);
1611         if (starget->can_queue > 0)
1612                 atomic_inc(&starget->target_busy);
1613
1614         blk_complete_request(req);
1615 }
1616
1617 static void scsi_softirq_done(struct request *rq)
1618 {
1619         struct scsi_cmnd *cmd = rq->special;
1620         unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1621         int disposition;
1622
1623         INIT_LIST_HEAD(&cmd->eh_entry);
1624
1625         atomic_inc(&cmd->device->iodone_cnt);
1626         if (cmd->result)
1627                 atomic_inc(&cmd->device->ioerr_cnt);
1628
1629         disposition = scsi_decide_disposition(cmd);
1630         if (disposition != SUCCESS &&
1631             time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1632                 sdev_printk(KERN_ERR, cmd->device,
1633                             "timing out command, waited %lus\n",
1634                             wait_for/HZ);
1635                 disposition = SUCCESS;
1636         }
1637
1638         scsi_log_completion(cmd, disposition);
1639
1640         switch (disposition) {
1641                 case SUCCESS:
1642                         scsi_finish_command(cmd);
1643                         break;
1644                 case NEEDS_RETRY:
1645                         scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1646                         break;
1647                 case ADD_TO_MLQUEUE:
1648                         scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1649                         break;
1650                 default:
1651                         if (!scsi_eh_scmd_add(cmd, 0))
1652                                 scsi_finish_command(cmd);
1653         }
1654 }
1655
1656 /**
1657  * scsi_dispatch_command - Dispatch a command to the low-level driver.
1658  * @cmd: command block we are dispatching.
1659  *
1660  * Return: nonzero return request was rejected and device's queue needs to be
1661  * plugged.
1662  */
1663 static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
1664 {
1665         struct Scsi_Host *host = cmd->device->host;
1666         int rtn = 0;
1667
1668         atomic_inc(&cmd->device->iorequest_cnt);
1669
1670         /* check if the device is still usable */
1671         if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
1672                 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
1673                  * returns an immediate error upwards, and signals
1674                  * that the device is no longer present */
1675                 cmd->result = DID_NO_CONNECT << 16;
1676                 goto done;
1677         }
1678
1679         /* Check to see if the scsi lld made this device blocked. */
1680         if (unlikely(scsi_device_blocked(cmd->device))) {
1681                 /*
1682                  * in blocked state, the command is just put back on
1683                  * the device queue.  The suspend state has already
1684                  * blocked the queue so future requests should not
1685                  * occur until the device transitions out of the
1686                  * suspend state.
1687                  */
1688                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1689                         "queuecommand : device blocked\n"));
1690                 return SCSI_MLQUEUE_DEVICE_BUSY;
1691         }
1692
1693         /* Store the LUN value in cmnd, if needed. */
1694         if (cmd->device->lun_in_cdb)
1695                 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
1696                                (cmd->device->lun << 5 & 0xe0);
1697
1698         scsi_log_send(cmd);
1699
1700         /*
1701          * Before we queue this command, check if the command
1702          * length exceeds what the host adapter can handle.
1703          */
1704         if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
1705                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1706                                "queuecommand : command too long. "
1707                                "cdb_size=%d host->max_cmd_len=%d\n",
1708                                cmd->cmd_len, cmd->device->host->max_cmd_len));
1709                 cmd->result = (DID_ABORT << 16);
1710                 goto done;
1711         }
1712
1713         if (unlikely(host->shost_state == SHOST_DEL)) {
1714                 cmd->result = (DID_NO_CONNECT << 16);
1715                 goto done;
1716
1717         }
1718
1719         trace_scsi_dispatch_cmd_start(cmd);
1720         rtn = host->hostt->queuecommand(host, cmd);
1721         if (rtn) {
1722                 trace_scsi_dispatch_cmd_error(cmd, rtn);
1723                 if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
1724                     rtn != SCSI_MLQUEUE_TARGET_BUSY)
1725                         rtn = SCSI_MLQUEUE_HOST_BUSY;
1726
1727                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1728                         "queuecommand : request rejected\n"));
1729         }
1730
1731         return rtn;
1732  done:
1733         cmd->scsi_done(cmd);
1734         return 0;
1735 }
1736
1737 /**
1738  * scsi_done - Invoke completion on finished SCSI command.
1739  * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
1740  * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
1741  *
1742  * Description: This function is the mid-level's (SCSI Core) interrupt routine,
1743  * which regains ownership of the SCSI command (de facto) from a LLDD, and
1744  * calls blk_complete_request() for further processing.
1745  *
1746  * This function is interrupt context safe.
1747  */
1748 static void scsi_done(struct scsi_cmnd *cmd)
1749 {
1750         trace_scsi_dispatch_cmd_done(cmd);
1751         blk_complete_request(cmd->request);
1752 }
1753
1754 /*
1755  * Function:    scsi_request_fn()
1756  *
1757  * Purpose:     Main strategy routine for SCSI.
1758  *
1759  * Arguments:   q       - Pointer to actual queue.
1760  *
1761  * Returns:     Nothing
1762  *
1763  * Lock status: IO request lock assumed to be held when called.
1764  */
1765 static void scsi_request_fn(struct request_queue *q)
1766         __releases(q->queue_lock)
1767         __acquires(q->queue_lock)
1768 {
1769         struct scsi_device *sdev = q->queuedata;
1770         struct Scsi_Host *shost;
1771         struct scsi_cmnd *cmd;
1772         struct request *req;
1773
1774         /*
1775          * To start with, we keep looping until the queue is empty, or until
1776          * the host is no longer able to accept any more requests.
1777          */
1778         shost = sdev->host;
1779         for (;;) {
1780                 int rtn;
1781                 /*
1782                  * get next queueable request.  We do this early to make sure
1783                  * that the request is fully prepared even if we cannot
1784                  * accept it.
1785                  */
1786                 req = blk_peek_request(q);
1787                 if (!req)
1788                         break;
1789
1790                 if (unlikely(!scsi_device_online(sdev))) {
1791                         sdev_printk(KERN_ERR, sdev,
1792                                     "rejecting I/O to offline device\n");
1793                         scsi_kill_request(req, q);
1794                         continue;
1795                 }
1796
1797                 if (!scsi_dev_queue_ready(q, sdev))
1798                         break;
1799
1800                 /*
1801                  * Remove the request from the request list.
1802                  */
1803                 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1804                         blk_start_request(req);
1805
1806                 spin_unlock_irq(q->queue_lock);
1807                 cmd = req->special;
1808                 if (unlikely(cmd == NULL)) {
1809                         printk(KERN_CRIT "impossible request in %s.\n"
1810                                          "please mail a stack trace to "
1811                                          "linux-scsi@vger.kernel.org\n",
1812                                          __func__);
1813                         blk_dump_rq_flags(req, "foo");
1814                         BUG();
1815                 }
1816
1817                 /*
1818                  * We hit this when the driver is using a host wide
1819                  * tag map. For device level tag maps the queue_depth check
1820                  * in the device ready fn would prevent us from trying
1821                  * to allocate a tag. Since the map is a shared host resource
1822                  * we add the dev to the starved list so it eventually gets
1823                  * a run when a tag is freed.
1824                  */
1825                 if (blk_queue_tagged(q) && !(req->cmd_flags & REQ_QUEUED)) {
1826                         spin_lock_irq(shost->host_lock);
1827                         if (list_empty(&sdev->starved_entry))
1828                                 list_add_tail(&sdev->starved_entry,
1829                                               &shost->starved_list);
1830                         spin_unlock_irq(shost->host_lock);
1831                         goto not_ready;
1832                 }
1833
1834                 if (!scsi_target_queue_ready(shost, sdev))
1835                         goto not_ready;
1836
1837                 if (!scsi_host_queue_ready(q, shost, sdev))
1838                         goto host_not_ready;
1839         
1840                 if (sdev->simple_tags)
1841                         cmd->flags |= SCMD_TAGGED;
1842                 else
1843                         cmd->flags &= ~SCMD_TAGGED;
1844
1845                 /*
1846                  * Finally, initialize any error handling parameters, and set up
1847                  * the timers for timeouts.
1848                  */
1849                 scsi_init_cmd_errh(cmd);
1850
1851                 /*
1852                  * Dispatch the command to the low-level driver.
1853                  */
1854                 cmd->scsi_done = scsi_done;
1855                 rtn = scsi_dispatch_cmd(cmd);
1856                 if (rtn) {
1857                         scsi_queue_insert(cmd, rtn);
1858                         spin_lock_irq(q->queue_lock);
1859                         goto out_delay;
1860                 }
1861                 spin_lock_irq(q->queue_lock);
1862         }
1863
1864         return;
1865
1866  host_not_ready:
1867         if (scsi_target(sdev)->can_queue > 0)
1868                 atomic_dec(&scsi_target(sdev)->target_busy);
1869  not_ready:
1870         /*
1871          * lock q, handle tag, requeue req, and decrement device_busy. We
1872          * must return with queue_lock held.
1873          *
1874          * Decrementing device_busy without checking it is OK, as all such
1875          * cases (host limits or settings) should run the queue at some
1876          * later time.
1877          */
1878         spin_lock_irq(q->queue_lock);
1879         blk_requeue_request(q, req);
1880         atomic_dec(&sdev->device_busy);
1881 out_delay:
1882         if (!atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev))
1883                 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1884 }
1885
1886 static inline int prep_to_mq(int ret)
1887 {
1888         switch (ret) {
1889         case BLKPREP_OK:
1890                 return 0;
1891         case BLKPREP_DEFER:
1892                 return BLK_MQ_RQ_QUEUE_BUSY;
1893         default:
1894                 return BLK_MQ_RQ_QUEUE_ERROR;
1895         }
1896 }
1897
1898 static int scsi_mq_prep_fn(struct request *req)
1899 {
1900         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1901         struct scsi_device *sdev = req->q->queuedata;
1902         struct Scsi_Host *shost = sdev->host;
1903         unsigned char *sense_buf = cmd->sense_buffer;
1904         struct scatterlist *sg;
1905
1906         memset(cmd, 0, sizeof(struct scsi_cmnd));
1907
1908         req->special = cmd;
1909
1910         cmd->request = req;
1911         cmd->device = sdev;
1912         cmd->sense_buffer = sense_buf;
1913
1914         cmd->tag = req->tag;
1915
1916         cmd->cmnd = req->cmd;
1917         cmd->prot_op = SCSI_PROT_NORMAL;
1918
1919         INIT_LIST_HEAD(&cmd->list);
1920         INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
1921         cmd->jiffies_at_alloc = jiffies;
1922
1923         if (shost->use_cmd_list) {
1924                 spin_lock_irq(&sdev->list_lock);
1925                 list_add_tail(&cmd->list, &sdev->cmd_list);
1926                 spin_unlock_irq(&sdev->list_lock);
1927         }
1928
1929         sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
1930         cmd->sdb.table.sgl = sg;
1931
1932         if (scsi_host_get_prot(shost)) {
1933                 cmd->prot_sdb = (void *)sg +
1934                         min_t(unsigned int,
1935                               shost->sg_tablesize, SCSI_MAX_SG_SEGMENTS) *
1936                         sizeof(struct scatterlist);
1937                 memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
1938
1939                 cmd->prot_sdb->table.sgl =
1940                         (struct scatterlist *)(cmd->prot_sdb + 1);
1941         }
1942
1943         if (blk_bidi_rq(req)) {
1944                 struct request *next_rq = req->next_rq;
1945                 struct scsi_data_buffer *bidi_sdb = blk_mq_rq_to_pdu(next_rq);
1946
1947                 memset(bidi_sdb, 0, sizeof(struct scsi_data_buffer));
1948                 bidi_sdb->table.sgl =
1949                         (struct scatterlist *)(bidi_sdb + 1);
1950
1951                 next_rq->special = bidi_sdb;
1952         }
1953
1954         blk_mq_start_request(req);
1955
1956         return scsi_setup_cmnd(sdev, req);
1957 }
1958
1959 static void scsi_mq_done(struct scsi_cmnd *cmd)
1960 {
1961         trace_scsi_dispatch_cmd_done(cmd);
1962         blk_mq_complete_request(cmd->request, cmd->request->errors);
1963 }
1964
1965 static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
1966                          const struct blk_mq_queue_data *bd)
1967 {
1968         struct request *req = bd->rq;
1969         struct request_queue *q = req->q;
1970         struct scsi_device *sdev = q->queuedata;
1971         struct Scsi_Host *shost = sdev->host;
1972         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1973         int ret;
1974         int reason;
1975
1976         ret = prep_to_mq(scsi_prep_state_check(sdev, req));
1977         if (ret)
1978                 goto out;
1979
1980         ret = BLK_MQ_RQ_QUEUE_BUSY;
1981         if (!get_device(&sdev->sdev_gendev))
1982                 goto out;
1983
1984         if (!scsi_dev_queue_ready(q, sdev))
1985                 goto out_put_device;
1986         if (!scsi_target_queue_ready(shost, sdev))
1987                 goto out_dec_device_busy;
1988         if (!scsi_host_queue_ready(q, shost, sdev))
1989                 goto out_dec_target_busy;
1990
1991
1992         if (!(req->cmd_flags & REQ_DONTPREP)) {
1993                 ret = prep_to_mq(scsi_mq_prep_fn(req));
1994                 if (ret)
1995                         goto out_dec_host_busy;
1996                 req->cmd_flags |= REQ_DONTPREP;
1997         } else {
1998                 blk_mq_start_request(req);
1999         }
2000
2001         if (sdev->simple_tags)
2002                 cmd->flags |= SCMD_TAGGED;
2003         else
2004                 cmd->flags &= ~SCMD_TAGGED;
2005
2006         scsi_init_cmd_errh(cmd);
2007         cmd->scsi_done = scsi_mq_done;
2008
2009         reason = scsi_dispatch_cmd(cmd);
2010         if (reason) {
2011                 scsi_set_blocked(cmd, reason);
2012                 ret = BLK_MQ_RQ_QUEUE_BUSY;
2013                 goto out_dec_host_busy;
2014         }
2015
2016         return BLK_MQ_RQ_QUEUE_OK;
2017
2018 out_dec_host_busy:
2019         atomic_dec(&shost->host_busy);
2020 out_dec_target_busy:
2021         if (scsi_target(sdev)->can_queue > 0)
2022                 atomic_dec(&scsi_target(sdev)->target_busy);
2023 out_dec_device_busy:
2024         atomic_dec(&sdev->device_busy);
2025 out_put_device:
2026         put_device(&sdev->sdev_gendev);
2027 out:
2028         switch (ret) {
2029         case BLK_MQ_RQ_QUEUE_BUSY:
2030                 blk_mq_stop_hw_queue(hctx);
2031                 if (atomic_read(&sdev->device_busy) == 0 &&
2032                     !scsi_device_blocked(sdev))
2033                         blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY);
2034                 break;
2035         case BLK_MQ_RQ_QUEUE_ERROR:
2036                 /*
2037                  * Make sure to release all allocated ressources when
2038                  * we hit an error, as we will never see this command
2039                  * again.
2040                  */
2041                 if (req->cmd_flags & REQ_DONTPREP)
2042                         scsi_mq_uninit_cmd(cmd);
2043                 break;
2044         default:
2045                 break;
2046         }
2047         return ret;
2048 }
2049
2050 static enum blk_eh_timer_return scsi_timeout(struct request *req,
2051                 bool reserved)
2052 {
2053         if (reserved)
2054                 return BLK_EH_RESET_TIMER;
2055         return scsi_times_out(req);
2056 }
2057
2058 static int scsi_init_request(void *data, struct request *rq,
2059                 unsigned int hctx_idx, unsigned int request_idx,
2060                 unsigned int numa_node)
2061 {
2062         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
2063
2064         cmd->sense_buffer = kzalloc_node(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL,
2065                         numa_node);
2066         if (!cmd->sense_buffer)
2067                 return -ENOMEM;
2068         return 0;
2069 }
2070
2071 static void scsi_exit_request(void *data, struct request *rq,
2072                 unsigned int hctx_idx, unsigned int request_idx)
2073 {
2074         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
2075
2076         kfree(cmd->sense_buffer);
2077 }
2078
2079 static u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
2080 {
2081         struct device *host_dev;
2082         u64 bounce_limit = 0xffffffff;
2083
2084         if (shost->unchecked_isa_dma)
2085                 return BLK_BOUNCE_ISA;
2086         /*
2087          * Platforms with virtual-DMA translation
2088          * hardware have no practical limit.
2089          */
2090         if (!PCI_DMA_BUS_IS_PHYS)
2091                 return BLK_BOUNCE_ANY;
2092
2093         host_dev = scsi_get_device(shost);
2094         if (host_dev && host_dev->dma_mask)
2095                 bounce_limit = (u64)dma_max_pfn(host_dev) << PAGE_SHIFT;
2096
2097         return bounce_limit;
2098 }
2099
2100 static void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
2101 {
2102         struct device *dev = shost->dma_dev;
2103
2104         /*
2105          * this limit is imposed by hardware restrictions
2106          */
2107         blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
2108                                         SCSI_MAX_SG_CHAIN_SEGMENTS));
2109
2110         if (scsi_host_prot_dma(shost)) {
2111                 shost->sg_prot_tablesize =
2112                         min_not_zero(shost->sg_prot_tablesize,
2113                                      (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
2114                 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
2115                 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
2116         }
2117
2118         blk_queue_max_hw_sectors(q, shost->max_sectors);
2119         blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
2120         blk_queue_segment_boundary(q, shost->dma_boundary);
2121         dma_set_seg_boundary(dev, shost->dma_boundary);
2122
2123         blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
2124
2125         if (!shost->use_clustering)
2126                 q->limits.cluster = 0;
2127
2128         /*
2129          * set a reasonable default alignment on word boundaries: the
2130          * host and device may alter it using
2131          * blk_queue_update_dma_alignment() later.
2132          */
2133         blk_queue_dma_alignment(q, 0x03);
2134 }
2135
2136 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
2137                                          request_fn_proc *request_fn)
2138 {
2139         struct request_queue *q;
2140
2141         q = blk_init_queue(request_fn, NULL);
2142         if (!q)
2143                 return NULL;
2144         __scsi_init_queue(shost, q);
2145         return q;
2146 }
2147 EXPORT_SYMBOL(__scsi_alloc_queue);
2148
2149 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
2150 {
2151         struct request_queue *q;
2152
2153         q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
2154         if (!q)
2155                 return NULL;
2156
2157         blk_queue_prep_rq(q, scsi_prep_fn);
2158         blk_queue_unprep_rq(q, scsi_unprep_fn);
2159         blk_queue_softirq_done(q, scsi_softirq_done);
2160         blk_queue_rq_timed_out(q, scsi_times_out);
2161         blk_queue_lld_busy(q, scsi_lld_busy);
2162         return q;
2163 }
2164
2165 static struct blk_mq_ops scsi_mq_ops = {
2166         .map_queue      = blk_mq_map_queue,
2167         .queue_rq       = scsi_queue_rq,
2168         .complete       = scsi_softirq_done,
2169         .timeout        = scsi_timeout,
2170         .init_request   = scsi_init_request,
2171         .exit_request   = scsi_exit_request,
2172 };
2173
2174 struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
2175 {
2176         sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set);
2177         if (IS_ERR(sdev->request_queue))
2178                 return NULL;
2179
2180         sdev->request_queue->queuedata = sdev;
2181         __scsi_init_queue(sdev->host, sdev->request_queue);
2182         return sdev->request_queue;
2183 }
2184
2185 int scsi_mq_setup_tags(struct Scsi_Host *shost)
2186 {
2187         unsigned int cmd_size, sgl_size, tbl_size;
2188
2189         tbl_size = shost->sg_tablesize;
2190         if (tbl_size > SCSI_MAX_SG_SEGMENTS)
2191                 tbl_size = SCSI_MAX_SG_SEGMENTS;
2192         sgl_size = tbl_size * sizeof(struct scatterlist);
2193         cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
2194         if (scsi_host_get_prot(shost))
2195                 cmd_size += sizeof(struct scsi_data_buffer) + sgl_size;
2196
2197         memset(&shost->tag_set, 0, sizeof(shost->tag_set));
2198         shost->tag_set.ops = &scsi_mq_ops;
2199         shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
2200         shost->tag_set.queue_depth = shost->can_queue;
2201         shost->tag_set.cmd_size = cmd_size;
2202         shost->tag_set.numa_node = NUMA_NO_NODE;
2203         shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
2204         shost->tag_set.flags |=
2205                 BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
2206         shost->tag_set.driver_data = shost;
2207
2208         return blk_mq_alloc_tag_set(&shost->tag_set);
2209 }
2210
2211 void scsi_mq_destroy_tags(struct Scsi_Host *shost)
2212 {
2213         blk_mq_free_tag_set(&shost->tag_set);
2214 }
2215
2216 /*
2217  * Function:    scsi_block_requests()
2218  *
2219  * Purpose:     Utility function used by low-level drivers to prevent further
2220  *              commands from being queued to the device.
2221  *
2222  * Arguments:   shost       - Host in question
2223  *
2224  * Returns:     Nothing
2225  *
2226  * Lock status: No locks are assumed held.
2227  *
2228  * Notes:       There is no timer nor any other means by which the requests
2229  *              get unblocked other than the low-level driver calling
2230  *              scsi_unblock_requests().
2231  */
2232 void scsi_block_requests(struct Scsi_Host *shost)
2233 {
2234         shost->host_self_blocked = 1;
2235 }
2236 EXPORT_SYMBOL(scsi_block_requests);
2237
2238 /*
2239  * Function:    scsi_unblock_requests()
2240  *
2241  * Purpose:     Utility function used by low-level drivers to allow further
2242  *              commands from being queued to the device.
2243  *
2244  * Arguments:   shost       - Host in question
2245  *
2246  * Returns:     Nothing
2247  *
2248  * Lock status: No locks are assumed held.
2249  *
2250  * Notes:       There is no timer nor any other means by which the requests
2251  *              get unblocked other than the low-level driver calling
2252  *              scsi_unblock_requests().
2253  *
2254  *              This is done as an API function so that changes to the
2255  *              internals of the scsi mid-layer won't require wholesale
2256  *              changes to drivers that use this feature.
2257  */
2258 void scsi_unblock_requests(struct Scsi_Host *shost)
2259 {
2260         shost->host_self_blocked = 0;
2261         scsi_run_host_queues(shost);
2262 }
2263 EXPORT_SYMBOL(scsi_unblock_requests);
2264
2265 int __init scsi_init_queue(void)
2266 {
2267         int i;
2268
2269         scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
2270                                            sizeof(struct scsi_data_buffer),
2271                                            0, 0, NULL);
2272         if (!scsi_sdb_cache) {
2273                 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
2274                 return -ENOMEM;
2275         }
2276
2277         for (i = 0; i < SG_MEMPOOL_NR; i++) {
2278                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
2279                 int size = sgp->size * sizeof(struct scatterlist);
2280
2281                 sgp->slab = kmem_cache_create(sgp->name, size, 0,
2282                                 SLAB_HWCACHE_ALIGN, NULL);
2283                 if (!sgp->slab) {
2284                         printk(KERN_ERR "SCSI: can't init sg slab %s\n",
2285                                         sgp->name);
2286                         goto cleanup_sdb;
2287                 }
2288
2289                 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
2290                                                      sgp->slab);
2291                 if (!sgp->pool) {
2292                         printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
2293                                         sgp->name);
2294                         goto cleanup_sdb;
2295                 }
2296         }
2297
2298         return 0;
2299
2300 cleanup_sdb:
2301         for (i = 0; i < SG_MEMPOOL_NR; i++) {
2302                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
2303                 if (sgp->pool)
2304                         mempool_destroy(sgp->pool);
2305                 if (sgp->slab)
2306                         kmem_cache_destroy(sgp->slab);
2307         }
2308         kmem_cache_destroy(scsi_sdb_cache);
2309
2310         return -ENOMEM;
2311 }
2312
2313 void scsi_exit_queue(void)
2314 {
2315         int i;
2316
2317         kmem_cache_destroy(scsi_sdb_cache);
2318
2319         for (i = 0; i < SG_MEMPOOL_NR; i++) {
2320                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
2321                 mempool_destroy(sgp->pool);
2322                 kmem_cache_destroy(sgp->slab);
2323         }
2324 }
2325
2326 /**
2327  *      scsi_mode_select - issue a mode select
2328  *      @sdev:  SCSI device to be queried
2329  *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
2330  *      @sp:    Save page bit (0 == don't save, 1 == save)
2331  *      @modepage: mode page being requested
2332  *      @buffer: request buffer (may not be smaller than eight bytes)
2333  *      @len:   length of request buffer.
2334  *      @timeout: command timeout
2335  *      @retries: number of retries before failing
2336  *      @data: returns a structure abstracting the mode header data
2337  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2338  *              must be SCSI_SENSE_BUFFERSIZE big.
2339  *
2340  *      Returns zero if successful; negative error number or scsi
2341  *      status on error
2342  *
2343  */
2344 int
2345 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
2346                  unsigned char *buffer, int len, int timeout, int retries,
2347                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2348 {
2349         unsigned char cmd[10];
2350         unsigned char *real_buffer;
2351         int ret;
2352
2353         memset(cmd, 0, sizeof(cmd));
2354         cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
2355
2356         if (sdev->use_10_for_ms) {
2357                 if (len > 65535)
2358                         return -EINVAL;
2359                 real_buffer = kmalloc(8 + len, GFP_KERNEL);
2360                 if (!real_buffer)
2361                         return -ENOMEM;
2362                 memcpy(real_buffer + 8, buffer, len);
2363                 len += 8;
2364                 real_buffer[0] = 0;
2365                 real_buffer[1] = 0;
2366                 real_buffer[2] = data->medium_type;
2367                 real_buffer[3] = data->device_specific;
2368                 real_buffer[4] = data->longlba ? 0x01 : 0;
2369                 real_buffer[5] = 0;
2370                 real_buffer[6] = data->block_descriptor_length >> 8;
2371                 real_buffer[7] = data->block_descriptor_length;
2372
2373                 cmd[0] = MODE_SELECT_10;
2374                 cmd[7] = len >> 8;
2375                 cmd[8] = len;
2376         } else {
2377                 if (len > 255 || data->block_descriptor_length > 255 ||
2378                     data->longlba)
2379                         return -EINVAL;
2380
2381                 real_buffer = kmalloc(4 + len, GFP_KERNEL);
2382                 if (!real_buffer)
2383                         return -ENOMEM;
2384                 memcpy(real_buffer + 4, buffer, len);
2385                 len += 4;
2386                 real_buffer[0] = 0;
2387                 real_buffer[1] = data->medium_type;
2388                 real_buffer[2] = data->device_specific;
2389                 real_buffer[3] = data->block_descriptor_length;
2390                 
2391
2392                 cmd[0] = MODE_SELECT;
2393                 cmd[4] = len;
2394         }
2395
2396         ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2397                                sshdr, timeout, retries, NULL);
2398         kfree(real_buffer);
2399         return ret;
2400 }
2401 EXPORT_SYMBOL_GPL(scsi_mode_select);
2402
2403 /**
2404  *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2405  *      @sdev:  SCSI device to be queried
2406  *      @dbd:   set if mode sense will allow block descriptors to be returned
2407  *      @modepage: mode page being requested
2408  *      @buffer: request buffer (may not be smaller than eight bytes)
2409  *      @len:   length of request buffer.
2410  *      @timeout: command timeout
2411  *      @retries: number of retries before failing
2412  *      @data: returns a structure abstracting the mode header data
2413  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2414  *              must be SCSI_SENSE_BUFFERSIZE big.
2415  *
2416  *      Returns zero if unsuccessful, or the header offset (either 4
2417  *      or 8 depending on whether a six or ten byte command was
2418  *      issued) if successful.
2419  */
2420 int
2421 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2422                   unsigned char *buffer, int len, int timeout, int retries,
2423                   struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2424 {
2425         unsigned char cmd[12];
2426         int use_10_for_ms;
2427         int header_length;
2428         int result, retry_count = retries;
2429         struct scsi_sense_hdr my_sshdr;
2430
2431         memset(data, 0, sizeof(*data));
2432         memset(&cmd[0], 0, 12);
2433         cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
2434         cmd[2] = modepage;
2435
2436         /* caller might not be interested in sense, but we need it */
2437         if (!sshdr)
2438                 sshdr = &my_sshdr;
2439
2440  retry:
2441         use_10_for_ms = sdev->use_10_for_ms;
2442
2443         if (use_10_for_ms) {
2444                 if (len < 8)
2445                         len = 8;
2446
2447                 cmd[0] = MODE_SENSE_10;
2448                 cmd[8] = len;
2449                 header_length = 8;
2450         } else {
2451                 if (len < 4)
2452                         len = 4;
2453
2454                 cmd[0] = MODE_SENSE;
2455                 cmd[4] = len;
2456                 header_length = 4;
2457         }
2458
2459         memset(buffer, 0, len);
2460
2461         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2462                                   sshdr, timeout, retries, NULL);
2463
2464         /* This code looks awful: what it's doing is making sure an
2465          * ILLEGAL REQUEST sense return identifies the actual command
2466          * byte as the problem.  MODE_SENSE commands can return
2467          * ILLEGAL REQUEST if the code page isn't supported */
2468
2469         if (use_10_for_ms && !scsi_status_is_good(result) &&
2470             (driver_byte(result) & DRIVER_SENSE)) {
2471                 if (scsi_sense_valid(sshdr)) {
2472                         if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2473                             (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2474                                 /* 
2475                                  * Invalid command operation code
2476                                  */
2477                                 sdev->use_10_for_ms = 0;
2478                                 goto retry;
2479                         }
2480                 }
2481         }
2482
2483         if(scsi_status_is_good(result)) {
2484                 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2485                              (modepage == 6 || modepage == 8))) {
2486                         /* Initio breakage? */
2487                         header_length = 0;
2488                         data->length = 13;
2489                         data->medium_type = 0;
2490                         data->device_specific = 0;
2491                         data->longlba = 0;
2492                         data->block_descriptor_length = 0;
2493                 } else if(use_10_for_ms) {
2494                         data->length = buffer[0]*256 + buffer[1] + 2;
2495                         data->medium_type = buffer[2];
2496                         data->device_specific = buffer[3];
2497                         data->longlba = buffer[4] & 0x01;
2498                         data->block_descriptor_length = buffer[6]*256
2499                                 + buffer[7];
2500                 } else {
2501                         data->length = buffer[0] + 1;
2502                         data->medium_type = buffer[1];
2503                         data->device_specific = buffer[2];
2504                         data->block_descriptor_length = buffer[3];
2505                 }
2506                 data->header_length = header_length;
2507         } else if ((status_byte(result) == CHECK_CONDITION) &&
2508                    scsi_sense_valid(sshdr) &&
2509                    sshdr->sense_key == UNIT_ATTENTION && retry_count) {
2510                 retry_count--;
2511                 goto retry;
2512         }
2513
2514         return result;
2515 }
2516 EXPORT_SYMBOL(scsi_mode_sense);
2517
2518 /**
2519  *      scsi_test_unit_ready - test if unit is ready
2520  *      @sdev:  scsi device to change the state of.
2521  *      @timeout: command timeout
2522  *      @retries: number of retries before failing
2523  *      @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2524  *              returning sense. Make sure that this is cleared before passing
2525  *              in.
2526  *
2527  *      Returns zero if unsuccessful or an error if TUR failed.  For
2528  *      removable media, UNIT_ATTENTION sets ->changed flag.
2529  **/
2530 int
2531 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2532                      struct scsi_sense_hdr *sshdr_external)
2533 {
2534         char cmd[] = {
2535                 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2536         };
2537         struct scsi_sense_hdr *sshdr;
2538         int result;
2539
2540         if (!sshdr_external)
2541                 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2542         else
2543                 sshdr = sshdr_external;
2544
2545         /* try to eat the UNIT_ATTENTION if there are enough retries */
2546         do {
2547                 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2548                                           timeout, retries, NULL);
2549                 if (sdev->removable && scsi_sense_valid(sshdr) &&
2550                     sshdr->sense_key == UNIT_ATTENTION)
2551                         sdev->changed = 1;
2552         } while (scsi_sense_valid(sshdr) &&
2553                  sshdr->sense_key == UNIT_ATTENTION && --retries);
2554
2555         if (!sshdr_external)
2556                 kfree(sshdr);
2557         return result;
2558 }
2559 EXPORT_SYMBOL(scsi_test_unit_ready);
2560
2561 /**
2562  *      scsi_device_set_state - Take the given device through the device state model.
2563  *      @sdev:  scsi device to change the state of.
2564  *      @state: state to change to.
2565  *
2566  *      Returns zero if unsuccessful or an error if the requested 
2567  *      transition is illegal.
2568  */
2569 int
2570 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2571 {
2572         enum scsi_device_state oldstate = sdev->sdev_state;
2573
2574         if (state == oldstate)
2575                 return 0;
2576
2577         switch (state) {
2578         case SDEV_CREATED:
2579                 switch (oldstate) {
2580                 case SDEV_CREATED_BLOCK:
2581                         break;
2582                 default:
2583                         goto illegal;
2584                 }
2585                 break;
2586                         
2587         case SDEV_RUNNING:
2588                 switch (oldstate) {
2589                 case SDEV_CREATED:
2590                 case SDEV_OFFLINE:
2591                 case SDEV_TRANSPORT_OFFLINE:
2592                 case SDEV_QUIESCE:
2593                 case SDEV_BLOCK:
2594                         break;
2595                 default:
2596                         goto illegal;
2597                 }
2598                 break;
2599
2600         case SDEV_QUIESCE:
2601                 switch (oldstate) {
2602                 case SDEV_RUNNING:
2603                 case SDEV_OFFLINE:
2604                 case SDEV_TRANSPORT_OFFLINE:
2605                         break;
2606                 default:
2607                         goto illegal;
2608                 }
2609                 break;
2610
2611         case SDEV_OFFLINE:
2612         case SDEV_TRANSPORT_OFFLINE:
2613                 switch (oldstate) {
2614                 case SDEV_CREATED:
2615                 case SDEV_RUNNING:
2616                 case SDEV_QUIESCE:
2617                 case SDEV_BLOCK:
2618                         break;
2619                 default:
2620                         goto illegal;
2621                 }
2622                 break;
2623
2624         case SDEV_BLOCK:
2625                 switch (oldstate) {
2626                 case SDEV_RUNNING:
2627                 case SDEV_CREATED_BLOCK:
2628                         break;
2629                 default:
2630                         goto illegal;
2631                 }
2632                 break;
2633
2634         case SDEV_CREATED_BLOCK:
2635                 switch (oldstate) {
2636                 case SDEV_CREATED:
2637                         break;
2638                 default:
2639                         goto illegal;
2640                 }
2641                 break;
2642
2643         case SDEV_CANCEL:
2644                 switch (oldstate) {
2645                 case SDEV_CREATED:
2646                 case SDEV_RUNNING:
2647                 case SDEV_QUIESCE:
2648                 case SDEV_OFFLINE:
2649                 case SDEV_TRANSPORT_OFFLINE:
2650                 case SDEV_BLOCK:
2651                         break;
2652                 default:
2653                         goto illegal;
2654                 }
2655                 break;
2656
2657         case SDEV_DEL:
2658                 switch (oldstate) {
2659                 case SDEV_CREATED:
2660                 case SDEV_RUNNING:
2661                 case SDEV_OFFLINE:
2662                 case SDEV_TRANSPORT_OFFLINE:
2663                 case SDEV_CANCEL:
2664                 case SDEV_CREATED_BLOCK:
2665                         break;
2666                 default:
2667                         goto illegal;
2668                 }
2669                 break;
2670
2671         }
2672         sdev->sdev_state = state;
2673         return 0;
2674
2675  illegal:
2676         SCSI_LOG_ERROR_RECOVERY(1,
2677                                 sdev_printk(KERN_ERR, sdev,
2678                                             "Illegal state transition %s->%s",
2679                                             scsi_device_state_name(oldstate),
2680                                             scsi_device_state_name(state))
2681                                 );
2682         return -EINVAL;
2683 }
2684 EXPORT_SYMBOL(scsi_device_set_state);
2685
2686 /**
2687  *      sdev_evt_emit - emit a single SCSI device uevent
2688  *      @sdev: associated SCSI device
2689  *      @evt: event to emit
2690  *
2691  *      Send a single uevent (scsi_event) to the associated scsi_device.
2692  */
2693 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2694 {
2695         int idx = 0;
2696         char *envp[3];
2697
2698         switch (evt->evt_type) {
2699         case SDEV_EVT_MEDIA_CHANGE:
2700                 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2701                 break;
2702         case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2703                 scsi_rescan_device(&sdev->sdev_gendev);
2704                 envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
2705                 break;
2706         case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2707                 envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
2708                 break;
2709         case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2710                envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
2711                 break;
2712         case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2713                 envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
2714                 break;
2715         case SDEV_EVT_LUN_CHANGE_REPORTED:
2716                 envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
2717                 break;
2718         case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2719                 envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
2720                 break;
2721         default:
2722                 /* do nothing */
2723                 break;
2724         }
2725
2726         envp[idx++] = NULL;
2727
2728         kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2729 }
2730
2731 /**
2732  *      sdev_evt_thread - send a uevent for each scsi event
2733  *      @work: work struct for scsi_device
2734  *
2735  *      Dispatch queued events to their associated scsi_device kobjects
2736  *      as uevents.
2737  */
2738 void scsi_evt_thread(struct work_struct *work)
2739 {
2740         struct scsi_device *sdev;
2741         enum scsi_device_event evt_type;
2742         LIST_HEAD(event_list);
2743
2744         sdev = container_of(work, struct scsi_device, event_work);
2745
2746         for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
2747                 if (test_and_clear_bit(evt_type, sdev->pending_events))
2748                         sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
2749
2750         while (1) {
2751                 struct scsi_event *evt;
2752                 struct list_head *this, *tmp;
2753                 unsigned long flags;
2754
2755                 spin_lock_irqsave(&sdev->list_lock, flags);
2756                 list_splice_init(&sdev->event_list, &event_list);
2757                 spin_unlock_irqrestore(&sdev->list_lock, flags);
2758
2759                 if (list_empty(&event_list))
2760                         break;
2761
2762                 list_for_each_safe(this, tmp, &event_list) {
2763                         evt = list_entry(this, struct scsi_event, node);
2764                         list_del(&evt->node);
2765                         scsi_evt_emit(sdev, evt);
2766                         kfree(evt);
2767                 }
2768         }
2769 }
2770
2771 /**
2772  *      sdev_evt_send - send asserted event to uevent thread
2773  *      @sdev: scsi_device event occurred on
2774  *      @evt: event to send
2775  *
2776  *      Assert scsi device event asynchronously.
2777  */
2778 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2779 {
2780         unsigned long flags;
2781
2782 #if 0
2783         /* FIXME: currently this check eliminates all media change events
2784          * for polled devices.  Need to update to discriminate between AN
2785          * and polled events */
2786         if (!test_bit(evt->evt_type, sdev->supported_events)) {
2787                 kfree(evt);
2788                 return;
2789         }
2790 #endif
2791
2792         spin_lock_irqsave(&sdev->list_lock, flags);
2793         list_add_tail(&evt->node, &sdev->event_list);
2794         schedule_work(&sdev->event_work);
2795         spin_unlock_irqrestore(&sdev->list_lock, flags);
2796 }
2797 EXPORT_SYMBOL_GPL(sdev_evt_send);
2798
2799 /**
2800  *      sdev_evt_alloc - allocate a new scsi event
2801  *      @evt_type: type of event to allocate
2802  *      @gfpflags: GFP flags for allocation
2803  *
2804  *      Allocates and returns a new scsi_event.
2805  */
2806 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2807                                   gfp_t gfpflags)
2808 {
2809         struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2810         if (!evt)
2811                 return NULL;
2812
2813         evt->evt_type = evt_type;
2814         INIT_LIST_HEAD(&evt->node);
2815
2816         /* evt_type-specific initialization, if any */
2817         switch (evt_type) {
2818         case SDEV_EVT_MEDIA_CHANGE:
2819         case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2820         case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2821         case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2822         case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2823         case SDEV_EVT_LUN_CHANGE_REPORTED:
2824         case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2825         default:
2826                 /* do nothing */
2827                 break;
2828         }
2829
2830         return evt;
2831 }
2832 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2833
2834 /**
2835  *      sdev_evt_send_simple - send asserted event to uevent thread
2836  *      @sdev: scsi_device event occurred on
2837  *      @evt_type: type of event to send
2838  *      @gfpflags: GFP flags for allocation
2839  *
2840  *      Assert scsi device event asynchronously, given an event type.
2841  */
2842 void sdev_evt_send_simple(struct scsi_device *sdev,
2843                           enum scsi_device_event evt_type, gfp_t gfpflags)
2844 {
2845         struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2846         if (!evt) {
2847                 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2848                             evt_type);
2849                 return;
2850         }
2851
2852         sdev_evt_send(sdev, evt);
2853 }
2854 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2855
2856 /**
2857  *      scsi_device_quiesce - Block user issued commands.
2858  *      @sdev:  scsi device to quiesce.
2859  *
2860  *      This works by trying to transition to the SDEV_QUIESCE state
2861  *      (which must be a legal transition).  When the device is in this
2862  *      state, only special requests will be accepted, all others will
2863  *      be deferred.  Since special requests may also be requeued requests,
2864  *      a successful return doesn't guarantee the device will be 
2865  *      totally quiescent.
2866  *
2867  *      Must be called with user context, may sleep.
2868  *
2869  *      Returns zero if unsuccessful or an error if not.
2870  */
2871 int
2872 scsi_device_quiesce(struct scsi_device *sdev)
2873 {
2874         int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2875         if (err)
2876                 return err;
2877
2878         scsi_run_queue(sdev->request_queue);
2879         while (atomic_read(&sdev->device_busy)) {
2880                 msleep_interruptible(200);
2881                 scsi_run_queue(sdev->request_queue);
2882         }
2883         return 0;
2884 }
2885 EXPORT_SYMBOL(scsi_device_quiesce);
2886
2887 /**
2888  *      scsi_device_resume - Restart user issued commands to a quiesced device.
2889  *      @sdev:  scsi device to resume.
2890  *
2891  *      Moves the device from quiesced back to running and restarts the
2892  *      queues.
2893  *
2894  *      Must be called with user context, may sleep.
2895  */
2896 void scsi_device_resume(struct scsi_device *sdev)
2897 {
2898         /* check if the device state was mutated prior to resume, and if
2899          * so assume the state is being managed elsewhere (for example
2900          * device deleted during suspend)
2901          */
2902         if (sdev->sdev_state != SDEV_QUIESCE ||
2903             scsi_device_set_state(sdev, SDEV_RUNNING))
2904                 return;
2905         scsi_run_queue(sdev->request_queue);
2906 }
2907 EXPORT_SYMBOL(scsi_device_resume);
2908
2909 static void
2910 device_quiesce_fn(struct scsi_device *sdev, void *data)
2911 {
2912         scsi_device_quiesce(sdev);
2913 }
2914
2915 void
2916 scsi_target_quiesce(struct scsi_target *starget)
2917 {
2918         starget_for_each_device(starget, NULL, device_quiesce_fn);
2919 }
2920 EXPORT_SYMBOL(scsi_target_quiesce);
2921
2922 static void
2923 device_resume_fn(struct scsi_device *sdev, void *data)
2924 {
2925         scsi_device_resume(sdev);
2926 }
2927
2928 void
2929 scsi_target_resume(struct scsi_target *starget)
2930 {
2931         starget_for_each_device(starget, NULL, device_resume_fn);
2932 }
2933 EXPORT_SYMBOL(scsi_target_resume);
2934
2935 /**
2936  * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2937  * @sdev:       device to block
2938  *
2939  * Block request made by scsi lld's to temporarily stop all
2940  * scsi commands on the specified device.  Called from interrupt
2941  * or normal process context.
2942  *
2943  * Returns zero if successful or error if not
2944  *
2945  * Notes:       
2946  *      This routine transitions the device to the SDEV_BLOCK state
2947  *      (which must be a legal transition).  When the device is in this
2948  *      state, all commands are deferred until the scsi lld reenables
2949  *      the device with scsi_device_unblock or device_block_tmo fires.
2950  */
2951 int
2952 scsi_internal_device_block(struct scsi_device *sdev)
2953 {
2954         struct request_queue *q = sdev->request_queue;
2955         unsigned long flags;
2956         int err = 0;
2957
2958         err = scsi_device_set_state(sdev, SDEV_BLOCK);
2959         if (err) {
2960                 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2961
2962                 if (err)
2963                         return err;
2964         }
2965
2966         /* 
2967          * The device has transitioned to SDEV_BLOCK.  Stop the
2968          * block layer from calling the midlayer with this device's
2969          * request queue. 
2970          */
2971         if (q->mq_ops) {
2972                 blk_mq_stop_hw_queues(q);
2973         } else {
2974                 spin_lock_irqsave(q->queue_lock, flags);
2975                 blk_stop_queue(q);
2976                 spin_unlock_irqrestore(q->queue_lock, flags);
2977         }
2978
2979         return 0;
2980 }
2981 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2982  
2983 /**
2984  * scsi_internal_device_unblock - resume a device after a block request
2985  * @sdev:       device to resume
2986  * @new_state:  state to set devices to after unblocking
2987  *
2988  * Called by scsi lld's or the midlayer to restart the device queue
2989  * for the previously suspended scsi device.  Called from interrupt or
2990  * normal process context.
2991  *
2992  * Returns zero if successful or error if not.
2993  *
2994  * Notes:       
2995  *      This routine transitions the device to the SDEV_RUNNING state
2996  *      or to one of the offline states (which must be a legal transition)
2997  *      allowing the midlayer to goose the queue for this device.
2998  */
2999 int
3000 scsi_internal_device_unblock(struct scsi_device *sdev,
3001                              enum scsi_device_state new_state)
3002 {
3003         struct request_queue *q = sdev->request_queue; 
3004         unsigned long flags;
3005
3006         /*
3007          * Try to transition the scsi device to SDEV_RUNNING or one of the
3008          * offlined states and goose the device queue if successful.
3009          */
3010         if ((sdev->sdev_state == SDEV_BLOCK) ||
3011             (sdev->sdev_state == SDEV_TRANSPORT_OFFLINE))
3012                 sdev->sdev_state = new_state;
3013         else if (sdev->sdev_state == SDEV_CREATED_BLOCK) {
3014                 if (new_state == SDEV_TRANSPORT_OFFLINE ||
3015                     new_state == SDEV_OFFLINE)
3016                         sdev->sdev_state = new_state;
3017                 else
3018                         sdev->sdev_state = SDEV_CREATED;
3019         } else if (sdev->sdev_state != SDEV_CANCEL &&
3020                  sdev->sdev_state != SDEV_OFFLINE)
3021                 return -EINVAL;
3022
3023         if (q->mq_ops) {
3024                 blk_mq_start_stopped_hw_queues(q, false);
3025         } else {
3026                 spin_lock_irqsave(q->queue_lock, flags);
3027                 blk_start_queue(q);
3028                 spin_unlock_irqrestore(q->queue_lock, flags);
3029         }
3030
3031         return 0;
3032 }
3033 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
3034
3035 static void
3036 device_block(struct scsi_device *sdev, void *data)
3037 {
3038         scsi_internal_device_block(sdev);
3039 }
3040
3041 static int
3042 target_block(struct device *dev, void *data)
3043 {
3044         if (scsi_is_target_device(dev))
3045                 starget_for_each_device(to_scsi_target(dev), NULL,
3046                                         device_block);
3047         return 0;
3048 }
3049
3050 void
3051 scsi_target_block(struct device *dev)
3052 {
3053         if (scsi_is_target_device(dev))
3054                 starget_for_each_device(to_scsi_target(dev), NULL,
3055                                         device_block);
3056         else
3057                 device_for_each_child(dev, NULL, target_block);
3058 }
3059 EXPORT_SYMBOL_GPL(scsi_target_block);
3060
3061 static void
3062 device_unblock(struct scsi_device *sdev, void *data)
3063 {
3064         scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
3065 }
3066
3067 static int
3068 target_unblock(struct device *dev, void *data)
3069 {
3070         if (scsi_is_target_device(dev))
3071                 starget_for_each_device(to_scsi_target(dev), data,
3072                                         device_unblock);
3073         return 0;
3074 }
3075
3076 void
3077 scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
3078 {
3079         if (scsi_is_target_device(dev))
3080                 starget_for_each_device(to_scsi_target(dev), &new_state,
3081                                         device_unblock);
3082         else
3083                 device_for_each_child(dev, &new_state, target_unblock);
3084 }
3085 EXPORT_SYMBOL_GPL(scsi_target_unblock);
3086
3087 /**
3088  * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
3089  * @sgl:        scatter-gather list
3090  * @sg_count:   number of segments in sg
3091  * @offset:     offset in bytes into sg, on return offset into the mapped area
3092  * @len:        bytes to map, on return number of bytes mapped
3093  *
3094  * Returns virtual address of the start of the mapped page
3095  */
3096 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
3097                           size_t *offset, size_t *len)
3098 {
3099         int i;
3100         size_t sg_len = 0, len_complete = 0;
3101         struct scatterlist *sg;
3102         struct page *page;
3103
3104         WARN_ON(!irqs_disabled());
3105
3106         for_each_sg(sgl, sg, sg_count, i) {
3107                 len_complete = sg_len; /* Complete sg-entries */
3108                 sg_len += sg->length;
3109                 if (sg_len > *offset)
3110                         break;
3111         }
3112
3113         if (unlikely(i == sg_count)) {
3114                 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
3115                         "elements %d\n",
3116                        __func__, sg_len, *offset, sg_count);
3117                 WARN_ON(1);
3118                 return NULL;
3119         }
3120
3121         /* Offset starting from the beginning of first page in this sg-entry */
3122         *offset = *offset - len_complete + sg->offset;
3123
3124         /* Assumption: contiguous pages can be accessed as "page + i" */
3125         page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
3126         *offset &= ~PAGE_MASK;
3127
3128         /* Bytes in this sg-entry from *offset to the end of the page */
3129         sg_len = PAGE_SIZE - *offset;
3130         if (*len > sg_len)
3131                 *len = sg_len;
3132
3133         return kmap_atomic(page);
3134 }
3135 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
3136
3137 /**
3138  * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
3139  * @virt:       virtual address to be unmapped
3140  */
3141 void scsi_kunmap_atomic_sg(void *virt)
3142 {
3143         kunmap_atomic(virt);
3144 }
3145 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
3146
3147 void sdev_disable_disk_events(struct scsi_device *sdev)
3148 {
3149         atomic_inc(&sdev->disk_events_disable_depth);
3150 }
3151 EXPORT_SYMBOL(sdev_disable_disk_events);
3152
3153 void sdev_enable_disk_events(struct scsi_device *sdev)
3154 {
3155         if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
3156                 return;
3157         atomic_dec(&sdev->disk_events_disable_depth);
3158 }
3159 EXPORT_SYMBOL(sdev_enable_disk_events);
3160
3161 /**
3162  * scsi_vpd_lun_id - return a unique device identification
3163  * @sdev: SCSI device
3164  * @id:   buffer for the identification
3165  * @id_len:  length of the buffer
3166  *
3167  * Copies a unique device identification into @id based
3168  * on the information in the VPD page 0x83 of the device.
3169  * The string will be formatted as a SCSI name string.
3170  *
3171  * Returns the length of the identification or error on failure.
3172  * If the identifier is longer than the supplied buffer the actual
3173  * identifier length is returned and the buffer is not zero-padded.
3174  */
3175 int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
3176 {
3177         u8 cur_id_type = 0xff;
3178         u8 cur_id_size = 0;
3179         unsigned char *d, *cur_id_str;
3180         unsigned char __rcu *vpd_pg83;
3181         int id_size = -EINVAL;
3182
3183         rcu_read_lock();
3184         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3185         if (!vpd_pg83) {
3186                 rcu_read_unlock();
3187                 return -ENXIO;
3188         }
3189
3190         /*
3191          * Look for the correct descriptor.
3192          * Order of preference for lun descriptor:
3193          * - SCSI name string
3194          * - NAA IEEE Registered Extended
3195          * - EUI-64 based 16-byte
3196          * - EUI-64 based 12-byte
3197          * - NAA IEEE Registered
3198          * - NAA IEEE Extended
3199          * as longer descriptors reduce the likelyhood
3200          * of identification clashes.
3201          */
3202
3203         /* The id string must be at least 20 bytes + terminating NULL byte */
3204         if (id_len < 21) {
3205                 rcu_read_unlock();
3206                 return -EINVAL;
3207         }
3208
3209         memset(id, 0, id_len);
3210         d = vpd_pg83 + 4;
3211         while (d < vpd_pg83 + sdev->vpd_pg83_len) {
3212                 /* Skip designators not referring to the LUN */
3213                 if ((d[1] & 0x30) != 0x00)
3214                         goto next_desig;
3215
3216                 switch (d[1] & 0xf) {
3217                 case 0x2:
3218                         /* EUI-64 */
3219                         if (cur_id_size > d[3])
3220                                 break;
3221                         /* Prefer NAA IEEE Registered Extended */
3222                         if (cur_id_type == 0x3 &&
3223                             cur_id_size == d[3])
3224                                 break;
3225                         cur_id_size = d[3];
3226                         cur_id_str = d + 4;
3227                         cur_id_type = d[1] & 0xf;
3228                         switch (cur_id_size) {
3229                         case 8:
3230                                 id_size = snprintf(id, id_len,
3231                                                    "eui.%8phN",
3232                                                    cur_id_str);
3233                                 break;
3234                         case 12:
3235                                 id_size = snprintf(id, id_len,
3236                                                    "eui.%12phN",
3237                                                    cur_id_str);
3238                                 break;
3239                         case 16:
3240                                 id_size = snprintf(id, id_len,
3241                                                    "eui.%16phN",
3242                                                    cur_id_str);
3243                                 break;
3244                         default:
3245                                 cur_id_size = 0;
3246                                 break;
3247                         }
3248                         break;
3249                 case 0x3:
3250                         /* NAA */
3251                         if (cur_id_size > d[3])
3252                                 break;
3253                         cur_id_size = d[3];
3254                         cur_id_str = d + 4;
3255                         cur_id_type = d[1] & 0xf;
3256                         switch (cur_id_size) {
3257                         case 8:
3258                                 id_size = snprintf(id, id_len,
3259                                                    "naa.%8phN",
3260                                                    cur_id_str);
3261                                 break;
3262                         case 16:
3263                                 id_size = snprintf(id, id_len,
3264                                                    "naa.%16phN",
3265                                                    cur_id_str);
3266                                 break;
3267                         default:
3268                                 cur_id_size = 0;
3269                                 break;
3270                         }
3271                         break;
3272                 case 0x8:
3273                         /* SCSI name string */
3274                         if (cur_id_size + 4 > d[3])
3275                                 break;
3276                         /* Prefer others for truncated descriptor */
3277                         if (cur_id_size && d[3] > id_len)
3278                                 break;
3279                         cur_id_size = id_size = d[3];
3280                         cur_id_str = d + 4;
3281                         cur_id_type = d[1] & 0xf;
3282                         if (cur_id_size >= id_len)
3283                                 cur_id_size = id_len - 1;
3284                         memcpy(id, cur_id_str, cur_id_size);
3285                         /* Decrease priority for truncated descriptor */
3286                         if (cur_id_size != id_size)
3287                                 cur_id_size = 6;
3288                         break;
3289                 default:
3290                         break;
3291                 }
3292 next_desig:
3293                 d += d[3] + 4;
3294         }
3295         rcu_read_unlock();
3296
3297         return id_size;
3298 }
3299 EXPORT_SYMBOL(scsi_vpd_lun_id);
3300
3301 /*
3302  * scsi_vpd_tpg_id - return a target port group identifier
3303  * @sdev: SCSI device
3304  *
3305  * Returns the Target Port Group identifier from the information
3306  * froom VPD page 0x83 of the device.
3307  *
3308  * Returns the identifier or error on failure.
3309  */
3310 int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
3311 {
3312         unsigned char *d;
3313         unsigned char __rcu *vpd_pg83;
3314         int group_id = -EAGAIN, rel_port = -1;
3315
3316         rcu_read_lock();
3317         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3318         if (!vpd_pg83) {
3319                 rcu_read_unlock();
3320                 return -ENXIO;
3321         }
3322
3323         d = sdev->vpd_pg83 + 4;
3324         while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
3325                 switch (d[1] & 0xf) {
3326                 case 0x4:
3327                         /* Relative target port */
3328                         rel_port = get_unaligned_be16(&d[6]);
3329                         break;
3330                 case 0x5:
3331                         /* Target port group */
3332                         group_id = get_unaligned_be16(&d[6]);
3333                         break;
3334                 default:
3335                         break;
3336                 }
3337                 d += d[3] + 4;
3338         }
3339         rcu_read_unlock();
3340
3341         if (group_id >= 0 && rel_id && rel_port != -1)
3342                 *rel_id = rel_port;
3343
3344         return group_id;
3345 }
3346 EXPORT_SYMBOL(scsi_vpd_tpg_id);