Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[sfrench/cifs-2.6.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/init.h>
18 #include <linux/pci.h>
19 #include <linux/delay.h>
20 #include <linux/hardirq.h>
21 #include <linux/scatterlist.h>
22 #include <linux/blk-mq.h>
23 #include <linux/ratelimit.h>
24 #include <asm/unaligned.h>
25
26 #include <scsi/scsi.h>
27 #include <scsi/scsi_cmnd.h>
28 #include <scsi/scsi_dbg.h>
29 #include <scsi/scsi_device.h>
30 #include <scsi/scsi_driver.h>
31 #include <scsi/scsi_eh.h>
32 #include <scsi/scsi_host.h>
33 #include <scsi/scsi_transport.h> /* __scsi_init_queue() */
34 #include <scsi/scsi_dh.h>
35
36 #include <trace/events/scsi.h>
37
38 #include "scsi_debugfs.h"
39 #include "scsi_priv.h"
40 #include "scsi_logging.h"
41
42 static struct kmem_cache *scsi_sdb_cache;
43 static struct kmem_cache *scsi_sense_cache;
44 static struct kmem_cache *scsi_sense_isadma_cache;
45 static DEFINE_MUTEX(scsi_sense_cache_mutex);
46
47 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
48
49 static inline struct kmem_cache *
50 scsi_select_sense_cache(bool unchecked_isa_dma)
51 {
52         return unchecked_isa_dma ? scsi_sense_isadma_cache : scsi_sense_cache;
53 }
54
55 static void scsi_free_sense_buffer(bool unchecked_isa_dma,
56                                    unsigned char *sense_buffer)
57 {
58         kmem_cache_free(scsi_select_sense_cache(unchecked_isa_dma),
59                         sense_buffer);
60 }
61
62 static unsigned char *scsi_alloc_sense_buffer(bool unchecked_isa_dma,
63         gfp_t gfp_mask, int numa_node)
64 {
65         return kmem_cache_alloc_node(scsi_select_sense_cache(unchecked_isa_dma),
66                                      gfp_mask, numa_node);
67 }
68
69 int scsi_init_sense_cache(struct Scsi_Host *shost)
70 {
71         struct kmem_cache *cache;
72         int ret = 0;
73
74         cache = scsi_select_sense_cache(shost->unchecked_isa_dma);
75         if (cache)
76                 return 0;
77
78         mutex_lock(&scsi_sense_cache_mutex);
79         if (shost->unchecked_isa_dma) {
80                 scsi_sense_isadma_cache =
81                         kmem_cache_create("scsi_sense_cache(DMA)",
82                                 SCSI_SENSE_BUFFERSIZE, 0,
83                                 SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA, NULL);
84                 if (!scsi_sense_isadma_cache)
85                         ret = -ENOMEM;
86         } else {
87                 scsi_sense_cache =
88                         kmem_cache_create_usercopy("scsi_sense_cache",
89                                 SCSI_SENSE_BUFFERSIZE, 0, SLAB_HWCACHE_ALIGN,
90                                 0, SCSI_SENSE_BUFFERSIZE, NULL);
91                 if (!scsi_sense_cache)
92                         ret = -ENOMEM;
93         }
94
95         mutex_unlock(&scsi_sense_cache_mutex);
96         return ret;
97 }
98
99 /*
100  * When to reinvoke queueing after a resource shortage. It's 3 msecs to
101  * not change behaviour from the previous unplug mechanism, experimentation
102  * may prove this needs changing.
103  */
104 #define SCSI_QUEUE_DELAY        3
105
106 static void
107 scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
108 {
109         struct Scsi_Host *host = cmd->device->host;
110         struct scsi_device *device = cmd->device;
111         struct scsi_target *starget = scsi_target(device);
112
113         /*
114          * Set the appropriate busy bit for the device/host.
115          *
116          * If the host/device isn't busy, assume that something actually
117          * completed, and that we should be able to queue a command now.
118          *
119          * Note that the prior mid-layer assumption that any host could
120          * always queue at least one command is now broken.  The mid-layer
121          * will implement a user specifiable stall (see
122          * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
123          * if a command is requeued with no other commands outstanding
124          * either for the device or for the host.
125          */
126         switch (reason) {
127         case SCSI_MLQUEUE_HOST_BUSY:
128                 atomic_set(&host->host_blocked, host->max_host_blocked);
129                 break;
130         case SCSI_MLQUEUE_DEVICE_BUSY:
131         case SCSI_MLQUEUE_EH_RETRY:
132                 atomic_set(&device->device_blocked,
133                            device->max_device_blocked);
134                 break;
135         case SCSI_MLQUEUE_TARGET_BUSY:
136                 atomic_set(&starget->target_blocked,
137                            starget->max_target_blocked);
138                 break;
139         }
140 }
141
142 static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
143 {
144         struct scsi_device *sdev = cmd->device;
145
146         if (cmd->request->rq_flags & RQF_DONTPREP) {
147                 cmd->request->rq_flags &= ~RQF_DONTPREP;
148                 scsi_mq_uninit_cmd(cmd);
149         } else {
150                 WARN_ON_ONCE(true);
151         }
152         blk_mq_requeue_request(cmd->request, true);
153         put_device(&sdev->sdev_gendev);
154 }
155
156 /**
157  * __scsi_queue_insert - private queue insertion
158  * @cmd: The SCSI command being requeued
159  * @reason:  The reason for the requeue
160  * @unbusy: Whether the queue should be unbusied
161  *
162  * This is a private queue insertion.  The public interface
163  * scsi_queue_insert() always assumes the queue should be unbusied
164  * because it's always called before the completion.  This function is
165  * for a requeue after completion, which should only occur in this
166  * file.
167  */
168 static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy)
169 {
170         struct scsi_device *device = cmd->device;
171
172         SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd,
173                 "Inserting command %p into mlqueue\n", cmd));
174
175         scsi_set_blocked(cmd, reason);
176
177         /*
178          * Decrement the counters, since these commands are no longer
179          * active on the host/device.
180          */
181         if (unbusy)
182                 scsi_device_unbusy(device);
183
184         /*
185          * Requeue this command.  It will go before all other commands
186          * that are already in the queue. Schedule requeue work under
187          * lock such that the kblockd_schedule_work() call happens
188          * before blk_cleanup_queue() finishes.
189          */
190         cmd->result = 0;
191
192         /*
193          * Before a SCSI command is dispatched,
194          * get_device(&sdev->sdev_gendev) is called and the host,
195          * target and device busy counters are increased. Since
196          * requeuing a request causes these actions to be repeated and
197          * since scsi_device_unbusy() has already been called,
198          * put_device(&device->sdev_gendev) must still be called. Call
199          * put_device() after blk_mq_requeue_request() to avoid that
200          * removal of the SCSI device can start before requeueing has
201          * happened.
202          */
203         blk_mq_requeue_request(cmd->request, true);
204         put_device(&device->sdev_gendev);
205 }
206
207 /*
208  * Function:    scsi_queue_insert()
209  *
210  * Purpose:     Insert a command in the midlevel queue.
211  *
212  * Arguments:   cmd    - command that we are adding to queue.
213  *              reason - why we are inserting command to queue.
214  *
215  * Lock status: Assumed that lock is not held upon entry.
216  *
217  * Returns:     Nothing.
218  *
219  * Notes:       We do this for one of two cases.  Either the host is busy
220  *              and it cannot accept any more commands for the time being,
221  *              or the device returned QUEUE_FULL and can accept no more
222  *              commands.
223  * Notes:       This could be called either from an interrupt context or a
224  *              normal process context.
225  */
226 void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
227 {
228         __scsi_queue_insert(cmd, reason, true);
229 }
230
231
232 /**
233  * __scsi_execute - insert request and wait for the result
234  * @sdev:       scsi device
235  * @cmd:        scsi command
236  * @data_direction: data direction
237  * @buffer:     data buffer
238  * @bufflen:    len of buffer
239  * @sense:      optional sense buffer
240  * @sshdr:      optional decoded sense header
241  * @timeout:    request timeout in seconds
242  * @retries:    number of times to retry request
243  * @flags:      flags for ->cmd_flags
244  * @rq_flags:   flags for ->rq_flags
245  * @resid:      optional residual length
246  *
247  * Returns the scsi_cmnd result field if a command was executed, or a negative
248  * Linux error code if we didn't get that far.
249  */
250 int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
251                  int data_direction, void *buffer, unsigned bufflen,
252                  unsigned char *sense, struct scsi_sense_hdr *sshdr,
253                  int timeout, int retries, u64 flags, req_flags_t rq_flags,
254                  int *resid)
255 {
256         struct request *req;
257         struct scsi_request *rq;
258         int ret = DRIVER_ERROR << 24;
259
260         req = blk_get_request(sdev->request_queue,
261                         data_direction == DMA_TO_DEVICE ?
262                         REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT);
263         if (IS_ERR(req))
264                 return ret;
265         rq = scsi_req(req);
266
267         if (bufflen &&  blk_rq_map_kern(sdev->request_queue, req,
268                                         buffer, bufflen, GFP_NOIO))
269                 goto out;
270
271         rq->cmd_len = COMMAND_SIZE(cmd[0]);
272         memcpy(rq->cmd, cmd, rq->cmd_len);
273         rq->retries = retries;
274         req->timeout = timeout;
275         req->cmd_flags |= flags;
276         req->rq_flags |= rq_flags | RQF_QUIET;
277
278         /*
279          * head injection *required* here otherwise quiesce won't work
280          */
281         blk_execute_rq(req->q, NULL, req, 1);
282
283         /*
284          * Some devices (USB mass-storage in particular) may transfer
285          * garbage data together with a residue indicating that the data
286          * is invalid.  Prevent the garbage from being misinterpreted
287          * and prevent security leaks by zeroing out the excess data.
288          */
289         if (unlikely(rq->resid_len > 0 && rq->resid_len <= bufflen))
290                 memset(buffer + (bufflen - rq->resid_len), 0, rq->resid_len);
291
292         if (resid)
293                 *resid = rq->resid_len;
294         if (sense && rq->sense_len)
295                 memcpy(sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
296         if (sshdr)
297                 scsi_normalize_sense(rq->sense, rq->sense_len, sshdr);
298         ret = rq->result;
299  out:
300         blk_put_request(req);
301
302         return ret;
303 }
304 EXPORT_SYMBOL(__scsi_execute);
305
306 /*
307  * Function:    scsi_init_cmd_errh()
308  *
309  * Purpose:     Initialize cmd fields related to error handling.
310  *
311  * Arguments:   cmd     - command that is ready to be queued.
312  *
313  * Notes:       This function has the job of initializing a number of
314  *              fields related to error handling.   Typically this will
315  *              be called once for each command, as required.
316  */
317 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
318 {
319         scsi_set_resid(cmd, 0);
320         memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
321         if (cmd->cmd_len == 0)
322                 cmd->cmd_len = scsi_command_size(cmd->cmnd);
323 }
324
325 /*
326  * Decrement the host_busy counter and wake up the error handler if necessary.
327  * Avoid as follows that the error handler is not woken up if shost->host_busy
328  * == shost->host_failed: use call_rcu() in scsi_eh_scmd_add() in combination
329  * with an RCU read lock in this function to ensure that this function in its
330  * entirety either finishes before scsi_eh_scmd_add() increases the
331  * host_failed counter or that it notices the shost state change made by
332  * scsi_eh_scmd_add().
333  */
334 static void scsi_dec_host_busy(struct Scsi_Host *shost)
335 {
336         unsigned long flags;
337
338         rcu_read_lock();
339         atomic_dec(&shost->host_busy);
340         if (unlikely(scsi_host_in_recovery(shost))) {
341                 spin_lock_irqsave(shost->host_lock, flags);
342                 if (shost->host_failed || shost->host_eh_scheduled)
343                         scsi_eh_wakeup(shost);
344                 spin_unlock_irqrestore(shost->host_lock, flags);
345         }
346         rcu_read_unlock();
347 }
348
349 void scsi_device_unbusy(struct scsi_device *sdev)
350 {
351         struct Scsi_Host *shost = sdev->host;
352         struct scsi_target *starget = scsi_target(sdev);
353
354         scsi_dec_host_busy(shost);
355
356         if (starget->can_queue > 0)
357                 atomic_dec(&starget->target_busy);
358
359         atomic_dec(&sdev->device_busy);
360 }
361
362 static void scsi_kick_queue(struct request_queue *q)
363 {
364         blk_mq_run_hw_queues(q, false);
365 }
366
367 /*
368  * Called for single_lun devices on IO completion. Clear starget_sdev_user,
369  * and call blk_run_queue for all the scsi_devices on the target -
370  * including current_sdev first.
371  *
372  * Called with *no* scsi locks held.
373  */
374 static void scsi_single_lun_run(struct scsi_device *current_sdev)
375 {
376         struct Scsi_Host *shost = current_sdev->host;
377         struct scsi_device *sdev, *tmp;
378         struct scsi_target *starget = scsi_target(current_sdev);
379         unsigned long flags;
380
381         spin_lock_irqsave(shost->host_lock, flags);
382         starget->starget_sdev_user = NULL;
383         spin_unlock_irqrestore(shost->host_lock, flags);
384
385         /*
386          * Call blk_run_queue for all LUNs on the target, starting with
387          * current_sdev. We race with others (to set starget_sdev_user),
388          * but in most cases, we will be first. Ideally, each LU on the
389          * target would get some limited time or requests on the target.
390          */
391         scsi_kick_queue(current_sdev->request_queue);
392
393         spin_lock_irqsave(shost->host_lock, flags);
394         if (starget->starget_sdev_user)
395                 goto out;
396         list_for_each_entry_safe(sdev, tmp, &starget->devices,
397                         same_target_siblings) {
398                 if (sdev == current_sdev)
399                         continue;
400                 if (scsi_device_get(sdev))
401                         continue;
402
403                 spin_unlock_irqrestore(shost->host_lock, flags);
404                 scsi_kick_queue(sdev->request_queue);
405                 spin_lock_irqsave(shost->host_lock, flags);
406         
407                 scsi_device_put(sdev);
408         }
409  out:
410         spin_unlock_irqrestore(shost->host_lock, flags);
411 }
412
413 static inline bool scsi_device_is_busy(struct scsi_device *sdev)
414 {
415         if (atomic_read(&sdev->device_busy) >= sdev->queue_depth)
416                 return true;
417         if (atomic_read(&sdev->device_blocked) > 0)
418                 return true;
419         return false;
420 }
421
422 static inline bool scsi_target_is_busy(struct scsi_target *starget)
423 {
424         if (starget->can_queue > 0) {
425                 if (atomic_read(&starget->target_busy) >= starget->can_queue)
426                         return true;
427                 if (atomic_read(&starget->target_blocked) > 0)
428                         return true;
429         }
430         return false;
431 }
432
433 static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
434 {
435         if (shost->can_queue > 0 &&
436             atomic_read(&shost->host_busy) >= shost->can_queue)
437                 return true;
438         if (atomic_read(&shost->host_blocked) > 0)
439                 return true;
440         if (shost->host_self_blocked)
441                 return true;
442         return false;
443 }
444
445 static void scsi_starved_list_run(struct Scsi_Host *shost)
446 {
447         LIST_HEAD(starved_list);
448         struct scsi_device *sdev;
449         unsigned long flags;
450
451         spin_lock_irqsave(shost->host_lock, flags);
452         list_splice_init(&shost->starved_list, &starved_list);
453
454         while (!list_empty(&starved_list)) {
455                 struct request_queue *slq;
456
457                 /*
458                  * As long as shost is accepting commands and we have
459                  * starved queues, call blk_run_queue. scsi_request_fn
460                  * drops the queue_lock and can add us back to the
461                  * starved_list.
462                  *
463                  * host_lock protects the starved_list and starved_entry.
464                  * scsi_request_fn must get the host_lock before checking
465                  * or modifying starved_list or starved_entry.
466                  */
467                 if (scsi_host_is_busy(shost))
468                         break;
469
470                 sdev = list_entry(starved_list.next,
471                                   struct scsi_device, starved_entry);
472                 list_del_init(&sdev->starved_entry);
473                 if (scsi_target_is_busy(scsi_target(sdev))) {
474                         list_move_tail(&sdev->starved_entry,
475                                        &shost->starved_list);
476                         continue;
477                 }
478
479                 /*
480                  * Once we drop the host lock, a racing scsi_remove_device()
481                  * call may remove the sdev from the starved list and destroy
482                  * it and the queue.  Mitigate by taking a reference to the
483                  * queue and never touching the sdev again after we drop the
484                  * host lock.  Note: if __scsi_remove_device() invokes
485                  * blk_cleanup_queue() before the queue is run from this
486                  * function then blk_run_queue() will return immediately since
487                  * blk_cleanup_queue() marks the queue with QUEUE_FLAG_DYING.
488                  */
489                 slq = sdev->request_queue;
490                 if (!blk_get_queue(slq))
491                         continue;
492                 spin_unlock_irqrestore(shost->host_lock, flags);
493
494                 scsi_kick_queue(slq);
495                 blk_put_queue(slq);
496
497                 spin_lock_irqsave(shost->host_lock, flags);
498         }
499         /* put any unprocessed entries back */
500         list_splice(&starved_list, &shost->starved_list);
501         spin_unlock_irqrestore(shost->host_lock, flags);
502 }
503
504 /*
505  * Function:   scsi_run_queue()
506  *
507  * Purpose:    Select a proper request queue to serve next
508  *
509  * Arguments:  q       - last request's queue
510  *
511  * Returns:     Nothing
512  *
513  * Notes:      The previous command was completely finished, start
514  *             a new one if possible.
515  */
516 static void scsi_run_queue(struct request_queue *q)
517 {
518         struct scsi_device *sdev = q->queuedata;
519
520         if (scsi_target(sdev)->single_lun)
521                 scsi_single_lun_run(sdev);
522         if (!list_empty(&sdev->host->starved_list))
523                 scsi_starved_list_run(sdev->host);
524
525         blk_mq_run_hw_queues(q, false);
526 }
527
528 void scsi_requeue_run_queue(struct work_struct *work)
529 {
530         struct scsi_device *sdev;
531         struct request_queue *q;
532
533         sdev = container_of(work, struct scsi_device, requeue_work);
534         q = sdev->request_queue;
535         scsi_run_queue(q);
536 }
537
538 void scsi_run_host_queues(struct Scsi_Host *shost)
539 {
540         struct scsi_device *sdev;
541
542         shost_for_each_device(sdev, shost)
543                 scsi_run_queue(sdev->request_queue);
544 }
545
546 static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
547 {
548         if (!blk_rq_is_passthrough(cmd->request)) {
549                 struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
550
551                 if (drv->uninit_command)
552                         drv->uninit_command(cmd);
553         }
554 }
555
556 static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
557 {
558         if (cmd->sdb.table.nents)
559                 sg_free_table_chained(&cmd->sdb.table, true);
560         if (scsi_prot_sg_count(cmd))
561                 sg_free_table_chained(&cmd->prot_sdb->table, true);
562 }
563
564 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
565 {
566         scsi_mq_free_sgtables(cmd);
567         scsi_uninit_cmd(cmd);
568         scsi_del_cmd_from_list(cmd);
569 }
570
571 /* Returns false when no more bytes to process, true if there are more */
572 static bool scsi_end_request(struct request *req, blk_status_t error,
573                 unsigned int bytes)
574 {
575         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
576         struct scsi_device *sdev = cmd->device;
577         struct request_queue *q = sdev->request_queue;
578
579         if (blk_update_request(req, error, bytes))
580                 return true;
581
582         if (blk_queue_add_random(q))
583                 add_disk_randomness(req->rq_disk);
584
585         if (!blk_rq_is_scsi(req)) {
586                 WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
587                 cmd->flags &= ~SCMD_INITIALIZED;
588         }
589
590         /*
591          * Calling rcu_barrier() is not necessary here because the
592          * SCSI error handler guarantees that the function called by
593          * call_rcu() has been called before scsi_end_request() is
594          * called.
595          */
596         destroy_rcu_head(&cmd->rcu);
597
598         /*
599          * In the MQ case the command gets freed by __blk_mq_end_request,
600          * so we have to do all cleanup that depends on it earlier.
601          *
602          * We also can't kick the queues from irq context, so we
603          * will have to defer it to a workqueue.
604          */
605         scsi_mq_uninit_cmd(cmd);
606
607         /*
608          * queue is still alive, so grab the ref for preventing it
609          * from being cleaned up during running queue.
610          */
611         percpu_ref_get(&q->q_usage_counter);
612
613         __blk_mq_end_request(req, error);
614
615         if (scsi_target(sdev)->single_lun ||
616             !list_empty(&sdev->host->starved_list))
617                 kblockd_schedule_work(&sdev->requeue_work);
618         else
619                 blk_mq_run_hw_queues(q, true);
620
621         percpu_ref_put(&q->q_usage_counter);
622         put_device(&sdev->sdev_gendev);
623         return false;
624 }
625
626 /**
627  * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
628  * @cmd:        SCSI command
629  * @result:     scsi error code
630  *
631  * Translate a SCSI result code into a blk_status_t value. May reset the host
632  * byte of @cmd->result.
633  */
634 static blk_status_t scsi_result_to_blk_status(struct scsi_cmnd *cmd, int result)
635 {
636         switch (host_byte(result)) {
637         case DID_OK:
638                 /*
639                  * Also check the other bytes than the status byte in result
640                  * to handle the case when a SCSI LLD sets result to
641                  * DRIVER_SENSE << 24 without setting SAM_STAT_CHECK_CONDITION.
642                  */
643                 if (scsi_status_is_good(result) && (result & ~0xff) == 0)
644                         return BLK_STS_OK;
645                 return BLK_STS_IOERR;
646         case DID_TRANSPORT_FAILFAST:
647                 return BLK_STS_TRANSPORT;
648         case DID_TARGET_FAILURE:
649                 set_host_byte(cmd, DID_OK);
650                 return BLK_STS_TARGET;
651         case DID_NEXUS_FAILURE:
652                 set_host_byte(cmd, DID_OK);
653                 return BLK_STS_NEXUS;
654         case DID_ALLOC_FAILURE:
655                 set_host_byte(cmd, DID_OK);
656                 return BLK_STS_NOSPC;
657         case DID_MEDIUM_ERROR:
658                 set_host_byte(cmd, DID_OK);
659                 return BLK_STS_MEDIUM;
660         default:
661                 return BLK_STS_IOERR;
662         }
663 }
664
665 /* Helper for scsi_io_completion() when "reprep" action required. */
666 static void scsi_io_completion_reprep(struct scsi_cmnd *cmd,
667                                       struct request_queue *q)
668 {
669         /* A new command will be prepared and issued. */
670         scsi_mq_requeue_cmd(cmd);
671 }
672
673 /* Helper for scsi_io_completion() when special action required. */
674 static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
675 {
676         struct request_queue *q = cmd->device->request_queue;
677         struct request *req = cmd->request;
678         int level = 0;
679         enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
680               ACTION_DELAYED_RETRY} action;
681         unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
682         struct scsi_sense_hdr sshdr;
683         bool sense_valid;
684         bool sense_current = true;      /* false implies "deferred sense" */
685         blk_status_t blk_stat;
686
687         sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
688         if (sense_valid)
689                 sense_current = !scsi_sense_is_deferred(&sshdr);
690
691         blk_stat = scsi_result_to_blk_status(cmd, result);
692
693         if (host_byte(result) == DID_RESET) {
694                 /* Third party bus reset or reset for error recovery
695                  * reasons.  Just retry the command and see what
696                  * happens.
697                  */
698                 action = ACTION_RETRY;
699         } else if (sense_valid && sense_current) {
700                 switch (sshdr.sense_key) {
701                 case UNIT_ATTENTION:
702                         if (cmd->device->removable) {
703                                 /* Detected disc change.  Set a bit
704                                  * and quietly refuse further access.
705                                  */
706                                 cmd->device->changed = 1;
707                                 action = ACTION_FAIL;
708                         } else {
709                                 /* Must have been a power glitch, or a
710                                  * bus reset.  Could not have been a
711                                  * media change, so we just retry the
712                                  * command and see what happens.
713                                  */
714                                 action = ACTION_RETRY;
715                         }
716                         break;
717                 case ILLEGAL_REQUEST:
718                         /* If we had an ILLEGAL REQUEST returned, then
719                          * we may have performed an unsupported
720                          * command.  The only thing this should be
721                          * would be a ten byte read where only a six
722                          * byte read was supported.  Also, on a system
723                          * where READ CAPACITY failed, we may have
724                          * read past the end of the disk.
725                          */
726                         if ((cmd->device->use_10_for_rw &&
727                             sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
728                             (cmd->cmnd[0] == READ_10 ||
729                              cmd->cmnd[0] == WRITE_10)) {
730                                 /* This will issue a new 6-byte command. */
731                                 cmd->device->use_10_for_rw = 0;
732                                 action = ACTION_REPREP;
733                         } else if (sshdr.asc == 0x10) /* DIX */ {
734                                 action = ACTION_FAIL;
735                                 blk_stat = BLK_STS_PROTECTION;
736                         /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
737                         } else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
738                                 action = ACTION_FAIL;
739                                 blk_stat = BLK_STS_TARGET;
740                         } else
741                                 action = ACTION_FAIL;
742                         break;
743                 case ABORTED_COMMAND:
744                         action = ACTION_FAIL;
745                         if (sshdr.asc == 0x10) /* DIF */
746                                 blk_stat = BLK_STS_PROTECTION;
747                         break;
748                 case NOT_READY:
749                         /* If the device is in the process of becoming
750                          * ready, or has a temporary blockage, retry.
751                          */
752                         if (sshdr.asc == 0x04) {
753                                 switch (sshdr.ascq) {
754                                 case 0x01: /* becoming ready */
755                                 case 0x04: /* format in progress */
756                                 case 0x05: /* rebuild in progress */
757                                 case 0x06: /* recalculation in progress */
758                                 case 0x07: /* operation in progress */
759                                 case 0x08: /* Long write in progress */
760                                 case 0x09: /* self test in progress */
761                                 case 0x14: /* space allocation in progress */
762                                 case 0x1a: /* start stop unit in progress */
763                                 case 0x1b: /* sanitize in progress */
764                                 case 0x1d: /* configuration in progress */
765                                 case 0x24: /* depopulation in progress */
766                                         action = ACTION_DELAYED_RETRY;
767                                         break;
768                                 default:
769                                         action = ACTION_FAIL;
770                                         break;
771                                 }
772                         } else
773                                 action = ACTION_FAIL;
774                         break;
775                 case VOLUME_OVERFLOW:
776                         /* See SSC3rXX or current. */
777                         action = ACTION_FAIL;
778                         break;
779                 default:
780                         action = ACTION_FAIL;
781                         break;
782                 }
783         } else
784                 action = ACTION_FAIL;
785
786         if (action != ACTION_FAIL &&
787             time_before(cmd->jiffies_at_alloc + wait_for, jiffies))
788                 action = ACTION_FAIL;
789
790         switch (action) {
791         case ACTION_FAIL:
792                 /* Give up and fail the remainder of the request */
793                 if (!(req->rq_flags & RQF_QUIET)) {
794                         static DEFINE_RATELIMIT_STATE(_rs,
795                                         DEFAULT_RATELIMIT_INTERVAL,
796                                         DEFAULT_RATELIMIT_BURST);
797
798                         if (unlikely(scsi_logging_level))
799                                 level =
800                                      SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
801                                                     SCSI_LOG_MLCOMPLETE_BITS);
802
803                         /*
804                          * if logging is enabled the failure will be printed
805                          * in scsi_log_completion(), so avoid duplicate messages
806                          */
807                         if (!level && __ratelimit(&_rs)) {
808                                 scsi_print_result(cmd, NULL, FAILED);
809                                 if (driver_byte(result) == DRIVER_SENSE)
810                                         scsi_print_sense(cmd);
811                                 scsi_print_command(cmd);
812                         }
813                 }
814                 if (!scsi_end_request(req, blk_stat, blk_rq_err_bytes(req)))
815                         return;
816                 /*FALLTHRU*/
817         case ACTION_REPREP:
818                 scsi_io_completion_reprep(cmd, q);
819                 break;
820         case ACTION_RETRY:
821                 /* Retry the same command immediately */
822                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, false);
823                 break;
824         case ACTION_DELAYED_RETRY:
825                 /* Retry the same command after a delay */
826                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, false);
827                 break;
828         }
829 }
830
831 /*
832  * Helper for scsi_io_completion() when cmd->result is non-zero. Returns a
833  * new result that may suppress further error checking. Also modifies
834  * *blk_statp in some cases.
835  */
836 static int scsi_io_completion_nz_result(struct scsi_cmnd *cmd, int result,
837                                         blk_status_t *blk_statp)
838 {
839         bool sense_valid;
840         bool sense_current = true;      /* false implies "deferred sense" */
841         struct request *req = cmd->request;
842         struct scsi_sense_hdr sshdr;
843
844         sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
845         if (sense_valid)
846                 sense_current = !scsi_sense_is_deferred(&sshdr);
847
848         if (blk_rq_is_passthrough(req)) {
849                 if (sense_valid) {
850                         /*
851                          * SG_IO wants current and deferred errors
852                          */
853                         scsi_req(req)->sense_len =
854                                 min(8 + cmd->sense_buffer[7],
855                                     SCSI_SENSE_BUFFERSIZE);
856                 }
857                 if (sense_current)
858                         *blk_statp = scsi_result_to_blk_status(cmd, result);
859         } else if (blk_rq_bytes(req) == 0 && sense_current) {
860                 /*
861                  * Flush commands do not transfers any data, and thus cannot use
862                  * good_bytes != blk_rq_bytes(req) as the signal for an error.
863                  * This sets *blk_statp explicitly for the problem case.
864                  */
865                 *blk_statp = scsi_result_to_blk_status(cmd, result);
866         }
867         /*
868          * Recovered errors need reporting, but they're always treated as
869          * success, so fiddle the result code here.  For passthrough requests
870          * we already took a copy of the original into sreq->result which
871          * is what gets returned to the user
872          */
873         if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
874                 bool do_print = true;
875                 /*
876                  * if ATA PASS-THROUGH INFORMATION AVAILABLE [0x0, 0x1d]
877                  * skip print since caller wants ATA registers. Only occurs
878                  * on SCSI ATA PASS_THROUGH commands when CK_COND=1
879                  */
880                 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
881                         do_print = false;
882                 else if (req->rq_flags & RQF_QUIET)
883                         do_print = false;
884                 if (do_print)
885                         scsi_print_sense(cmd);
886                 result = 0;
887                 /* for passthrough, *blk_statp may be set */
888                 *blk_statp = BLK_STS_OK;
889         }
890         /*
891          * Another corner case: the SCSI status byte is non-zero but 'good'.
892          * Example: PRE-FETCH command returns SAM_STAT_CONDITION_MET when
893          * it is able to fit nominated LBs in its cache (and SAM_STAT_GOOD
894          * if it can't fit). Treat SAM_STAT_CONDITION_MET and the related
895          * intermediate statuses (both obsolete in SAM-4) as good.
896          */
897         if (status_byte(result) && scsi_status_is_good(result)) {
898                 result = 0;
899                 *blk_statp = BLK_STS_OK;
900         }
901         return result;
902 }
903
904 /*
905  * Function:    scsi_io_completion()
906  *
907  * Purpose:     Completion processing for block device I/O requests.
908  *
909  * Arguments:   cmd   - command that is finished.
910  *
911  * Lock status: Assumed that no lock is held upon entry.
912  *
913  * Returns:     Nothing
914  *
915  * Notes:       We will finish off the specified number of sectors.  If we
916  *              are done, the command block will be released and the queue
917  *              function will be goosed.  If we are not done then we have to
918  *              figure out what to do next:
919  *
920  *              a) We can call scsi_requeue_command().  The request
921  *                 will be unprepared and put back on the queue.  Then
922  *                 a new command will be created for it.  This should
923  *                 be used if we made forward progress, or if we want
924  *                 to switch from READ(10) to READ(6) for example.
925  *
926  *              b) We can call __scsi_queue_insert().  The request will
927  *                 be put back on the queue and retried using the same
928  *                 command as before, possibly after a delay.
929  *
930  *              c) We can call scsi_end_request() with blk_stat other than
931  *                 BLK_STS_OK, to fail the remainder of the request.
932  */
933 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
934 {
935         int result = cmd->result;
936         struct request_queue *q = cmd->device->request_queue;
937         struct request *req = cmd->request;
938         blk_status_t blk_stat = BLK_STS_OK;
939
940         if (unlikely(result))   /* a nz result may or may not be an error */
941                 result = scsi_io_completion_nz_result(cmd, result, &blk_stat);
942
943         if (unlikely(blk_rq_is_passthrough(req))) {
944                 /*
945                  * scsi_result_to_blk_status may have reset the host_byte
946                  */
947                 scsi_req(req)->result = cmd->result;
948         }
949
950         /*
951          * Next deal with any sectors which we were able to correctly
952          * handle.
953          */
954         SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
955                 "%u sectors total, %d bytes done.\n",
956                 blk_rq_sectors(req), good_bytes));
957
958         /*
959          * Next deal with any sectors which we were able to correctly
960          * handle. Failed, zero length commands always need to drop down
961          * to retry code. Fast path should return in this block.
962          */
963         if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) {
964                 if (likely(!scsi_end_request(req, blk_stat, good_bytes)))
965                         return; /* no bytes remaining */
966         }
967
968         /* Kill remainder if no retries. */
969         if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) {
970                 if (scsi_end_request(req, blk_stat, blk_rq_bytes(req)))
971                         WARN_ONCE(true,
972                             "Bytes remaining after failed, no-retry command");
973                 return;
974         }
975
976         /*
977          * If there had been no error, but we have leftover bytes in the
978          * requeues just queue the command up again.
979          */
980         if (likely(result == 0))
981                 scsi_io_completion_reprep(cmd, q);
982         else
983                 scsi_io_completion_action(cmd, result);
984 }
985
986 static blk_status_t scsi_init_sgtable(struct request *req,
987                 struct scsi_data_buffer *sdb)
988 {
989         int count;
990
991         /*
992          * If sg table allocation fails, requeue request later.
993          */
994         if (unlikely(sg_alloc_table_chained(&sdb->table,
995                         blk_rq_nr_phys_segments(req), sdb->table.sgl)))
996                 return BLK_STS_RESOURCE;
997
998         /* 
999          * Next, walk the list, and fill in the addresses and sizes of
1000          * each segment.
1001          */
1002         count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1003         BUG_ON(count > sdb->table.nents);
1004         sdb->table.nents = count;
1005         sdb->length = blk_rq_payload_bytes(req);
1006         return BLK_STS_OK;
1007 }
1008
1009 /*
1010  * Function:    scsi_init_io()
1011  *
1012  * Purpose:     SCSI I/O initialize function.
1013  *
1014  * Arguments:   cmd   - Command descriptor we wish to initialize
1015  *
1016  * Returns:     BLK_STS_OK on success
1017  *              BLK_STS_RESOURCE if the failure is retryable
1018  *              BLK_STS_IOERR if the failure is fatal
1019  */
1020 blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
1021 {
1022         struct request *rq = cmd->request;
1023         blk_status_t ret;
1024
1025         if (WARN_ON_ONCE(!blk_rq_nr_phys_segments(rq)))
1026                 return BLK_STS_IOERR;
1027
1028         ret = scsi_init_sgtable(rq, &cmd->sdb);
1029         if (ret)
1030                 return ret;
1031
1032         if (blk_integrity_rq(rq)) {
1033                 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1034                 int ivecs, count;
1035
1036                 if (WARN_ON_ONCE(!prot_sdb)) {
1037                         /*
1038                          * This can happen if someone (e.g. multipath)
1039                          * queues a command to a device on an adapter
1040                          * that does not support DIX.
1041                          */
1042                         ret = BLK_STS_IOERR;
1043                         goto out_free_sgtables;
1044                 }
1045
1046                 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1047
1048                 if (sg_alloc_table_chained(&prot_sdb->table, ivecs,
1049                                 prot_sdb->table.sgl)) {
1050                         ret = BLK_STS_RESOURCE;
1051                         goto out_free_sgtables;
1052                 }
1053
1054                 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1055                                                 prot_sdb->table.sgl);
1056                 BUG_ON(count > ivecs);
1057                 BUG_ON(count > queue_max_integrity_segments(rq->q));
1058
1059                 cmd->prot_sdb = prot_sdb;
1060                 cmd->prot_sdb->table.nents = count;
1061         }
1062
1063         return BLK_STS_OK;
1064 out_free_sgtables:
1065         scsi_mq_free_sgtables(cmd);
1066         return ret;
1067 }
1068 EXPORT_SYMBOL(scsi_init_io);
1069
1070 /**
1071  * scsi_initialize_rq - initialize struct scsi_cmnd partially
1072  * @rq: Request associated with the SCSI command to be initialized.
1073  *
1074  * This function initializes the members of struct scsi_cmnd that must be
1075  * initialized before request processing starts and that won't be
1076  * reinitialized if a SCSI command is requeued.
1077  *
1078  * Called from inside blk_get_request() for pass-through requests and from
1079  * inside scsi_init_command() for filesystem requests.
1080  */
1081 static void scsi_initialize_rq(struct request *rq)
1082 {
1083         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1084
1085         scsi_req_init(&cmd->req);
1086         init_rcu_head(&cmd->rcu);
1087         cmd->jiffies_at_alloc = jiffies;
1088         cmd->retries = 0;
1089 }
1090
1091 /* Add a command to the list used by the aacraid and dpt_i2o drivers */
1092 void scsi_add_cmd_to_list(struct scsi_cmnd *cmd)
1093 {
1094         struct scsi_device *sdev = cmd->device;
1095         struct Scsi_Host *shost = sdev->host;
1096         unsigned long flags;
1097
1098         if (shost->use_cmd_list) {
1099                 spin_lock_irqsave(&sdev->list_lock, flags);
1100                 list_add_tail(&cmd->list, &sdev->cmd_list);
1101                 spin_unlock_irqrestore(&sdev->list_lock, flags);
1102         }
1103 }
1104
1105 /* Remove a command from the list used by the aacraid and dpt_i2o drivers */
1106 void scsi_del_cmd_from_list(struct scsi_cmnd *cmd)
1107 {
1108         struct scsi_device *sdev = cmd->device;
1109         struct Scsi_Host *shost = sdev->host;
1110         unsigned long flags;
1111
1112         if (shost->use_cmd_list) {
1113                 spin_lock_irqsave(&sdev->list_lock, flags);
1114                 BUG_ON(list_empty(&cmd->list));
1115                 list_del_init(&cmd->list);
1116                 spin_unlock_irqrestore(&sdev->list_lock, flags);
1117         }
1118 }
1119
1120 /* Called after a request has been started. */
1121 void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
1122 {
1123         void *buf = cmd->sense_buffer;
1124         void *prot = cmd->prot_sdb;
1125         struct request *rq = blk_mq_rq_from_pdu(cmd);
1126         unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
1127         unsigned long jiffies_at_alloc;
1128         int retries;
1129
1130         if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) {
1131                 flags |= SCMD_INITIALIZED;
1132                 scsi_initialize_rq(rq);
1133         }
1134
1135         jiffies_at_alloc = cmd->jiffies_at_alloc;
1136         retries = cmd->retries;
1137         /* zero out the cmd, except for the embedded scsi_request */
1138         memset((char *)cmd + sizeof(cmd->req), 0,
1139                 sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);
1140
1141         cmd->device = dev;
1142         cmd->sense_buffer = buf;
1143         cmd->prot_sdb = prot;
1144         cmd->flags = flags;
1145         INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
1146         cmd->jiffies_at_alloc = jiffies_at_alloc;
1147         cmd->retries = retries;
1148
1149         scsi_add_cmd_to_list(cmd);
1150 }
1151
1152 static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
1153                 struct request *req)
1154 {
1155         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1156
1157         /*
1158          * Passthrough requests may transfer data, in which case they must
1159          * a bio attached to them.  Or they might contain a SCSI command
1160          * that does not transfer data, in which case they may optionally
1161          * submit a request without an attached bio.
1162          */
1163         if (req->bio) {
1164                 blk_status_t ret = scsi_init_io(cmd);
1165                 if (unlikely(ret != BLK_STS_OK))
1166                         return ret;
1167         } else {
1168                 BUG_ON(blk_rq_bytes(req));
1169
1170                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1171         }
1172
1173         cmd->cmd_len = scsi_req(req)->cmd_len;
1174         cmd->cmnd = scsi_req(req)->cmd;
1175         cmd->transfersize = blk_rq_bytes(req);
1176         cmd->allowed = scsi_req(req)->retries;
1177         return BLK_STS_OK;
1178 }
1179
1180 /*
1181  * Setup a normal block command.  These are simple request from filesystems
1182  * that still need to be translated to SCSI CDBs from the ULD.
1183  */
1184 static blk_status_t scsi_setup_fs_cmnd(struct scsi_device *sdev,
1185                 struct request *req)
1186 {
1187         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1188
1189         if (unlikely(sdev->handler && sdev->handler->prep_fn)) {
1190                 blk_status_t ret = sdev->handler->prep_fn(sdev, req);
1191                 if (ret != BLK_STS_OK)
1192                         return ret;
1193         }
1194
1195         cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd;
1196         memset(cmd->cmnd, 0, BLK_MAX_CDB);
1197         return scsi_cmd_to_driver(cmd)->init_command(cmd);
1198 }
1199
1200 static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
1201                 struct request *req)
1202 {
1203         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1204
1205         if (!blk_rq_bytes(req))
1206                 cmd->sc_data_direction = DMA_NONE;
1207         else if (rq_data_dir(req) == WRITE)
1208                 cmd->sc_data_direction = DMA_TO_DEVICE;
1209         else
1210                 cmd->sc_data_direction = DMA_FROM_DEVICE;
1211
1212         if (blk_rq_is_scsi(req))
1213                 return scsi_setup_scsi_cmnd(sdev, req);
1214         else
1215                 return scsi_setup_fs_cmnd(sdev, req);
1216 }
1217
1218 static blk_status_t
1219 scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1220 {
1221         switch (sdev->sdev_state) {
1222         case SDEV_OFFLINE:
1223         case SDEV_TRANSPORT_OFFLINE:
1224                 /*
1225                  * If the device is offline we refuse to process any
1226                  * commands.  The device must be brought online
1227                  * before trying any recovery commands.
1228                  */
1229                 sdev_printk(KERN_ERR, sdev,
1230                             "rejecting I/O to offline device\n");
1231                 return BLK_STS_IOERR;
1232         case SDEV_DEL:
1233                 /*
1234                  * If the device is fully deleted, we refuse to
1235                  * process any commands as well.
1236                  */
1237                 sdev_printk(KERN_ERR, sdev,
1238                             "rejecting I/O to dead device\n");
1239                 return BLK_STS_IOERR;
1240         case SDEV_BLOCK:
1241         case SDEV_CREATED_BLOCK:
1242                 return BLK_STS_RESOURCE;
1243         case SDEV_QUIESCE:
1244                 /*
1245                  * If the devices is blocked we defer normal commands.
1246                  */
1247                 if (req && !(req->rq_flags & RQF_PREEMPT))
1248                         return BLK_STS_RESOURCE;
1249                 return BLK_STS_OK;
1250         default:
1251                 /*
1252                  * For any other not fully online state we only allow
1253                  * special commands.  In particular any user initiated
1254                  * command is not allowed.
1255                  */
1256                 if (req && !(req->rq_flags & RQF_PREEMPT))
1257                         return BLK_STS_IOERR;
1258                 return BLK_STS_OK;
1259         }
1260 }
1261
1262 /*
1263  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1264  * return 0.
1265  *
1266  * Called with the queue_lock held.
1267  */
1268 static inline int scsi_dev_queue_ready(struct request_queue *q,
1269                                   struct scsi_device *sdev)
1270 {
1271         unsigned int busy;
1272
1273         busy = atomic_inc_return(&sdev->device_busy) - 1;
1274         if (atomic_read(&sdev->device_blocked)) {
1275                 if (busy)
1276                         goto out_dec;
1277
1278                 /*
1279                  * unblock after device_blocked iterates to zero
1280                  */
1281                 if (atomic_dec_return(&sdev->device_blocked) > 0)
1282                         goto out_dec;
1283                 SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
1284                                    "unblocking device at zero depth\n"));
1285         }
1286
1287         if (busy >= sdev->queue_depth)
1288                 goto out_dec;
1289
1290         return 1;
1291 out_dec:
1292         atomic_dec(&sdev->device_busy);
1293         return 0;
1294 }
1295
1296 /*
1297  * scsi_target_queue_ready: checks if there we can send commands to target
1298  * @sdev: scsi device on starget to check.
1299  */
1300 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1301                                            struct scsi_device *sdev)
1302 {
1303         struct scsi_target *starget = scsi_target(sdev);
1304         unsigned int busy;
1305
1306         if (starget->single_lun) {
1307                 spin_lock_irq(shost->host_lock);
1308                 if (starget->starget_sdev_user &&
1309                     starget->starget_sdev_user != sdev) {
1310                         spin_unlock_irq(shost->host_lock);
1311                         return 0;
1312                 }
1313                 starget->starget_sdev_user = sdev;
1314                 spin_unlock_irq(shost->host_lock);
1315         }
1316
1317         if (starget->can_queue <= 0)
1318                 return 1;
1319
1320         busy = atomic_inc_return(&starget->target_busy) - 1;
1321         if (atomic_read(&starget->target_blocked) > 0) {
1322                 if (busy)
1323                         goto starved;
1324
1325                 /*
1326                  * unblock after target_blocked iterates to zero
1327                  */
1328                 if (atomic_dec_return(&starget->target_blocked) > 0)
1329                         goto out_dec;
1330
1331                 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1332                                  "unblocking target at zero depth\n"));
1333         }
1334
1335         if (busy >= starget->can_queue)
1336                 goto starved;
1337
1338         return 1;
1339
1340 starved:
1341         spin_lock_irq(shost->host_lock);
1342         list_move_tail(&sdev->starved_entry, &shost->starved_list);
1343         spin_unlock_irq(shost->host_lock);
1344 out_dec:
1345         if (starget->can_queue > 0)
1346                 atomic_dec(&starget->target_busy);
1347         return 0;
1348 }
1349
1350 /*
1351  * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1352  * return 0. We must end up running the queue again whenever 0 is
1353  * returned, else IO can hang.
1354  */
1355 static inline int scsi_host_queue_ready(struct request_queue *q,
1356                                    struct Scsi_Host *shost,
1357                                    struct scsi_device *sdev)
1358 {
1359         unsigned int busy;
1360
1361         if (scsi_host_in_recovery(shost))
1362                 return 0;
1363
1364         busy = atomic_inc_return(&shost->host_busy) - 1;
1365         if (atomic_read(&shost->host_blocked) > 0) {
1366                 if (busy)
1367                         goto starved;
1368
1369                 /*
1370                  * unblock after host_blocked iterates to zero
1371                  */
1372                 if (atomic_dec_return(&shost->host_blocked) > 0)
1373                         goto out_dec;
1374
1375                 SCSI_LOG_MLQUEUE(3,
1376                         shost_printk(KERN_INFO, shost,
1377                                      "unblocking host at zero depth\n"));
1378         }
1379
1380         if (shost->can_queue > 0 && busy >= shost->can_queue)
1381                 goto starved;
1382         if (shost->host_self_blocked)
1383                 goto starved;
1384
1385         /* We're OK to process the command, so we can't be starved */
1386         if (!list_empty(&sdev->starved_entry)) {
1387                 spin_lock_irq(shost->host_lock);
1388                 if (!list_empty(&sdev->starved_entry))
1389                         list_del_init(&sdev->starved_entry);
1390                 spin_unlock_irq(shost->host_lock);
1391         }
1392
1393         return 1;
1394
1395 starved:
1396         spin_lock_irq(shost->host_lock);
1397         if (list_empty(&sdev->starved_entry))
1398                 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1399         spin_unlock_irq(shost->host_lock);
1400 out_dec:
1401         scsi_dec_host_busy(shost);
1402         return 0;
1403 }
1404
1405 /*
1406  * Busy state exporting function for request stacking drivers.
1407  *
1408  * For efficiency, no lock is taken to check the busy state of
1409  * shost/starget/sdev, since the returned value is not guaranteed and
1410  * may be changed after request stacking drivers call the function,
1411  * regardless of taking lock or not.
1412  *
1413  * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1414  * needs to return 'not busy'. Otherwise, request stacking drivers
1415  * may hold requests forever.
1416  */
1417 static bool scsi_mq_lld_busy(struct request_queue *q)
1418 {
1419         struct scsi_device *sdev = q->queuedata;
1420         struct Scsi_Host *shost;
1421
1422         if (blk_queue_dying(q))
1423                 return false;
1424
1425         shost = sdev->host;
1426
1427         /*
1428          * Ignore host/starget busy state.
1429          * Since block layer does not have a concept of fairness across
1430          * multiple queues, congestion of host/starget needs to be handled
1431          * in SCSI layer.
1432          */
1433         if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1434                 return true;
1435
1436         return false;
1437 }
1438
1439 static void scsi_softirq_done(struct request *rq)
1440 {
1441         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1442         unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1443         int disposition;
1444
1445         INIT_LIST_HEAD(&cmd->eh_entry);
1446
1447         atomic_inc(&cmd->device->iodone_cnt);
1448         if (cmd->result)
1449                 atomic_inc(&cmd->device->ioerr_cnt);
1450
1451         disposition = scsi_decide_disposition(cmd);
1452         if (disposition != SUCCESS &&
1453             time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1454                 sdev_printk(KERN_ERR, cmd->device,
1455                             "timing out command, waited %lus\n",
1456                             wait_for/HZ);
1457                 disposition = SUCCESS;
1458         }
1459
1460         scsi_log_completion(cmd, disposition);
1461
1462         switch (disposition) {
1463                 case SUCCESS:
1464                         scsi_finish_command(cmd);
1465                         break;
1466                 case NEEDS_RETRY:
1467                         scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1468                         break;
1469                 case ADD_TO_MLQUEUE:
1470                         scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1471                         break;
1472                 default:
1473                         scsi_eh_scmd_add(cmd);
1474                         break;
1475         }
1476 }
1477
1478 /**
1479  * scsi_dispatch_command - Dispatch a command to the low-level driver.
1480  * @cmd: command block we are dispatching.
1481  *
1482  * Return: nonzero return request was rejected and device's queue needs to be
1483  * plugged.
1484  */
1485 static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
1486 {
1487         struct Scsi_Host *host = cmd->device->host;
1488         int rtn = 0;
1489
1490         atomic_inc(&cmd->device->iorequest_cnt);
1491
1492         /* check if the device is still usable */
1493         if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
1494                 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
1495                  * returns an immediate error upwards, and signals
1496                  * that the device is no longer present */
1497                 cmd->result = DID_NO_CONNECT << 16;
1498                 goto done;
1499         }
1500
1501         /* Check to see if the scsi lld made this device blocked. */
1502         if (unlikely(scsi_device_blocked(cmd->device))) {
1503                 /*
1504                  * in blocked state, the command is just put back on
1505                  * the device queue.  The suspend state has already
1506                  * blocked the queue so future requests should not
1507                  * occur until the device transitions out of the
1508                  * suspend state.
1509                  */
1510                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1511                         "queuecommand : device blocked\n"));
1512                 return SCSI_MLQUEUE_DEVICE_BUSY;
1513         }
1514
1515         /* Store the LUN value in cmnd, if needed. */
1516         if (cmd->device->lun_in_cdb)
1517                 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
1518                                (cmd->device->lun << 5 & 0xe0);
1519
1520         scsi_log_send(cmd);
1521
1522         /*
1523          * Before we queue this command, check if the command
1524          * length exceeds what the host adapter can handle.
1525          */
1526         if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
1527                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1528                                "queuecommand : command too long. "
1529                                "cdb_size=%d host->max_cmd_len=%d\n",
1530                                cmd->cmd_len, cmd->device->host->max_cmd_len));
1531                 cmd->result = (DID_ABORT << 16);
1532                 goto done;
1533         }
1534
1535         if (unlikely(host->shost_state == SHOST_DEL)) {
1536                 cmd->result = (DID_NO_CONNECT << 16);
1537                 goto done;
1538
1539         }
1540
1541         trace_scsi_dispatch_cmd_start(cmd);
1542         rtn = host->hostt->queuecommand(host, cmd);
1543         if (rtn) {
1544                 trace_scsi_dispatch_cmd_error(cmd, rtn);
1545                 if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
1546                     rtn != SCSI_MLQUEUE_TARGET_BUSY)
1547                         rtn = SCSI_MLQUEUE_HOST_BUSY;
1548
1549                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1550                         "queuecommand : request rejected\n"));
1551         }
1552
1553         return rtn;
1554  done:
1555         cmd->scsi_done(cmd);
1556         return 0;
1557 }
1558
1559 /* Size in bytes of the sg-list stored in the scsi-mq command-private data. */
1560 static unsigned int scsi_mq_sgl_size(struct Scsi_Host *shost)
1561 {
1562         return min_t(unsigned int, shost->sg_tablesize, SG_CHUNK_SIZE) *
1563                 sizeof(struct scatterlist);
1564 }
1565
1566 static blk_status_t scsi_mq_prep_fn(struct request *req)
1567 {
1568         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1569         struct scsi_device *sdev = req->q->queuedata;
1570         struct Scsi_Host *shost = sdev->host;
1571         struct scatterlist *sg;
1572
1573         scsi_init_command(sdev, cmd);
1574
1575         cmd->request = req;
1576         cmd->tag = req->tag;
1577         cmd->prot_op = SCSI_PROT_NORMAL;
1578
1579         sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
1580         cmd->sdb.table.sgl = sg;
1581
1582         if (scsi_host_get_prot(shost)) {
1583                 memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
1584
1585                 cmd->prot_sdb->table.sgl =
1586                         (struct scatterlist *)(cmd->prot_sdb + 1);
1587         }
1588
1589         blk_mq_start_request(req);
1590
1591         return scsi_setup_cmnd(sdev, req);
1592 }
1593
1594 static void scsi_mq_done(struct scsi_cmnd *cmd)
1595 {
1596         if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
1597                 return;
1598         trace_scsi_dispatch_cmd_done(cmd);
1599
1600         /*
1601          * If the block layer didn't complete the request due to a timeout
1602          * injection, scsi must clear its internal completed state so that the
1603          * timeout handler will see it needs to escalate its own error
1604          * recovery.
1605          */
1606         if (unlikely(!blk_mq_complete_request(cmd->request)))
1607                 clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
1608 }
1609
1610 static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx)
1611 {
1612         struct request_queue *q = hctx->queue;
1613         struct scsi_device *sdev = q->queuedata;
1614
1615         atomic_dec(&sdev->device_busy);
1616         put_device(&sdev->sdev_gendev);
1617 }
1618
1619 static bool scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)
1620 {
1621         struct request_queue *q = hctx->queue;
1622         struct scsi_device *sdev = q->queuedata;
1623
1624         if (!get_device(&sdev->sdev_gendev))
1625                 goto out;
1626         if (!scsi_dev_queue_ready(q, sdev))
1627                 goto out_put_device;
1628
1629         return true;
1630
1631 out_put_device:
1632         put_device(&sdev->sdev_gendev);
1633 out:
1634         if (atomic_read(&sdev->device_busy) == 0 && !scsi_device_blocked(sdev))
1635                 blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY);
1636         return false;
1637 }
1638
1639 static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
1640                          const struct blk_mq_queue_data *bd)
1641 {
1642         struct request *req = bd->rq;
1643         struct request_queue *q = req->q;
1644         struct scsi_device *sdev = q->queuedata;
1645         struct Scsi_Host *shost = sdev->host;
1646         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1647         blk_status_t ret;
1648         int reason;
1649
1650         /*
1651          * If the device is not in running state we will reject some or all
1652          * commands.
1653          */
1654         if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1655                 ret = scsi_prep_state_check(sdev, req);
1656                 if (ret != BLK_STS_OK)
1657                         goto out_put_budget;
1658         }
1659
1660         ret = BLK_STS_RESOURCE;
1661         if (!scsi_target_queue_ready(shost, sdev))
1662                 goto out_put_budget;
1663         if (!scsi_host_queue_ready(q, shost, sdev))
1664                 goto out_dec_target_busy;
1665
1666         if (!(req->rq_flags & RQF_DONTPREP)) {
1667                 ret = scsi_mq_prep_fn(req);
1668                 if (ret != BLK_STS_OK)
1669                         goto out_dec_host_busy;
1670                 req->rq_flags |= RQF_DONTPREP;
1671         } else {
1672                 clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
1673                 blk_mq_start_request(req);
1674         }
1675
1676         if (sdev->simple_tags)
1677                 cmd->flags |= SCMD_TAGGED;
1678         else
1679                 cmd->flags &= ~SCMD_TAGGED;
1680
1681         scsi_init_cmd_errh(cmd);
1682         cmd->scsi_done = scsi_mq_done;
1683
1684         reason = scsi_dispatch_cmd(cmd);
1685         if (reason) {
1686                 scsi_set_blocked(cmd, reason);
1687                 ret = BLK_STS_RESOURCE;
1688                 goto out_dec_host_busy;
1689         }
1690
1691         return BLK_STS_OK;
1692
1693 out_dec_host_busy:
1694         scsi_dec_host_busy(shost);
1695 out_dec_target_busy:
1696         if (scsi_target(sdev)->can_queue > 0)
1697                 atomic_dec(&scsi_target(sdev)->target_busy);
1698 out_put_budget:
1699         scsi_mq_put_budget(hctx);
1700         switch (ret) {
1701         case BLK_STS_OK:
1702                 break;
1703         case BLK_STS_RESOURCE:
1704                 if (atomic_read(&sdev->device_busy) ||
1705                     scsi_device_blocked(sdev))
1706                         ret = BLK_STS_DEV_RESOURCE;
1707                 break;
1708         default:
1709                 if (unlikely(!scsi_device_online(sdev)))
1710                         scsi_req(req)->result = DID_NO_CONNECT << 16;
1711                 else
1712                         scsi_req(req)->result = DID_ERROR << 16;
1713                 /*
1714                  * Make sure to release all allocated resources when
1715                  * we hit an error, as we will never see this command
1716                  * again.
1717                  */
1718                 if (req->rq_flags & RQF_DONTPREP)
1719                         scsi_mq_uninit_cmd(cmd);
1720                 break;
1721         }
1722         return ret;
1723 }
1724
1725 static enum blk_eh_timer_return scsi_timeout(struct request *req,
1726                 bool reserved)
1727 {
1728         if (reserved)
1729                 return BLK_EH_RESET_TIMER;
1730         return scsi_times_out(req);
1731 }
1732
1733 static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
1734                                 unsigned int hctx_idx, unsigned int numa_node)
1735 {
1736         struct Scsi_Host *shost = set->driver_data;
1737         const bool unchecked_isa_dma = shost->unchecked_isa_dma;
1738         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1739         struct scatterlist *sg;
1740
1741         if (unchecked_isa_dma)
1742                 cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
1743         cmd->sense_buffer = scsi_alloc_sense_buffer(unchecked_isa_dma,
1744                                                     GFP_KERNEL, numa_node);
1745         if (!cmd->sense_buffer)
1746                 return -ENOMEM;
1747         cmd->req.sense = cmd->sense_buffer;
1748
1749         if (scsi_host_get_prot(shost)) {
1750                 sg = (void *)cmd + sizeof(struct scsi_cmnd) +
1751                         shost->hostt->cmd_size;
1752                 cmd->prot_sdb = (void *)sg + scsi_mq_sgl_size(shost);
1753         }
1754
1755         return 0;
1756 }
1757
1758 static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
1759                                  unsigned int hctx_idx)
1760 {
1761         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1762
1763         scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,
1764                                cmd->sense_buffer);
1765 }
1766
1767 static int scsi_map_queues(struct blk_mq_tag_set *set)
1768 {
1769         struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
1770
1771         if (shost->hostt->map_queues)
1772                 return shost->hostt->map_queues(shost);
1773         return blk_mq_map_queues(&set->map[0]);
1774 }
1775
1776 void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
1777 {
1778         struct device *dev = shost->dma_dev;
1779
1780         /*
1781          * this limit is imposed by hardware restrictions
1782          */
1783         blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1784                                         SG_MAX_SEGMENTS));
1785
1786         if (scsi_host_prot_dma(shost)) {
1787                 shost->sg_prot_tablesize =
1788                         min_not_zero(shost->sg_prot_tablesize,
1789                                      (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1790                 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1791                 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1792         }
1793
1794         blk_queue_max_hw_sectors(q, shost->max_sectors);
1795         if (shost->unchecked_isa_dma)
1796                 blk_queue_bounce_limit(q, BLK_BOUNCE_ISA);
1797         blk_queue_segment_boundary(q, shost->dma_boundary);
1798         dma_set_seg_boundary(dev, shost->dma_boundary);
1799
1800         blk_queue_max_segment_size(q, shost->max_segment_size);
1801         dma_set_max_seg_size(dev, shost->max_segment_size);
1802
1803         /*
1804          * Set a reasonable default alignment:  The larger of 32-byte (dword),
1805          * which is a common minimum for HBAs, and the minimum DMA alignment,
1806          * which is set by the platform.
1807          *
1808          * Devices that require a bigger alignment can increase it later.
1809          */
1810         blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
1811 }
1812 EXPORT_SYMBOL_GPL(__scsi_init_queue);
1813
1814 static const struct blk_mq_ops scsi_mq_ops = {
1815         .get_budget     = scsi_mq_get_budget,
1816         .put_budget     = scsi_mq_put_budget,
1817         .queue_rq       = scsi_queue_rq,
1818         .complete       = scsi_softirq_done,
1819         .timeout        = scsi_timeout,
1820 #ifdef CONFIG_BLK_DEBUG_FS
1821         .show_rq        = scsi_show_rq,
1822 #endif
1823         .init_request   = scsi_mq_init_request,
1824         .exit_request   = scsi_mq_exit_request,
1825         .initialize_rq_fn = scsi_initialize_rq,
1826         .busy           = scsi_mq_lld_busy,
1827         .map_queues     = scsi_map_queues,
1828 };
1829
1830 struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
1831 {
1832         sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set);
1833         if (IS_ERR(sdev->request_queue))
1834                 return NULL;
1835
1836         sdev->request_queue->queuedata = sdev;
1837         __scsi_init_queue(sdev->host, sdev->request_queue);
1838         blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, sdev->request_queue);
1839         return sdev->request_queue;
1840 }
1841
1842 int scsi_mq_setup_tags(struct Scsi_Host *shost)
1843 {
1844         unsigned int cmd_size, sgl_size;
1845
1846         sgl_size = scsi_mq_sgl_size(shost);
1847         cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
1848         if (scsi_host_get_prot(shost))
1849                 cmd_size += sizeof(struct scsi_data_buffer) + sgl_size;
1850
1851         memset(&shost->tag_set, 0, sizeof(shost->tag_set));
1852         shost->tag_set.ops = &scsi_mq_ops;
1853         shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
1854         shost->tag_set.queue_depth = shost->can_queue;
1855         shost->tag_set.cmd_size = cmd_size;
1856         shost->tag_set.numa_node = NUMA_NO_NODE;
1857         shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1858         shost->tag_set.flags |=
1859                 BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
1860         shost->tag_set.driver_data = shost;
1861
1862         return blk_mq_alloc_tag_set(&shost->tag_set);
1863 }
1864
1865 void scsi_mq_destroy_tags(struct Scsi_Host *shost)
1866 {
1867         blk_mq_free_tag_set(&shost->tag_set);
1868 }
1869
1870 /**
1871  * scsi_device_from_queue - return sdev associated with a request_queue
1872  * @q: The request queue to return the sdev from
1873  *
1874  * Return the sdev associated with a request queue or NULL if the
1875  * request_queue does not reference a SCSI device.
1876  */
1877 struct scsi_device *scsi_device_from_queue(struct request_queue *q)
1878 {
1879         struct scsi_device *sdev = NULL;
1880
1881         if (q->mq_ops == &scsi_mq_ops)
1882                 sdev = q->queuedata;
1883         if (!sdev || !get_device(&sdev->sdev_gendev))
1884                 sdev = NULL;
1885
1886         return sdev;
1887 }
1888 EXPORT_SYMBOL_GPL(scsi_device_from_queue);
1889
1890 /*
1891  * Function:    scsi_block_requests()
1892  *
1893  * Purpose:     Utility function used by low-level drivers to prevent further
1894  *              commands from being queued to the device.
1895  *
1896  * Arguments:   shost       - Host in question
1897  *
1898  * Returns:     Nothing
1899  *
1900  * Lock status: No locks are assumed held.
1901  *
1902  * Notes:       There is no timer nor any other means by which the requests
1903  *              get unblocked other than the low-level driver calling
1904  *              scsi_unblock_requests().
1905  */
1906 void scsi_block_requests(struct Scsi_Host *shost)
1907 {
1908         shost->host_self_blocked = 1;
1909 }
1910 EXPORT_SYMBOL(scsi_block_requests);
1911
1912 /*
1913  * Function:    scsi_unblock_requests()
1914  *
1915  * Purpose:     Utility function used by low-level drivers to allow further
1916  *              commands from being queued to the device.
1917  *
1918  * Arguments:   shost       - Host in question
1919  *
1920  * Returns:     Nothing
1921  *
1922  * Lock status: No locks are assumed held.
1923  *
1924  * Notes:       There is no timer nor any other means by which the requests
1925  *              get unblocked other than the low-level driver calling
1926  *              scsi_unblock_requests().
1927  *
1928  *              This is done as an API function so that changes to the
1929  *              internals of the scsi mid-layer won't require wholesale
1930  *              changes to drivers that use this feature.
1931  */
1932 void scsi_unblock_requests(struct Scsi_Host *shost)
1933 {
1934         shost->host_self_blocked = 0;
1935         scsi_run_host_queues(shost);
1936 }
1937 EXPORT_SYMBOL(scsi_unblock_requests);
1938
1939 int __init scsi_init_queue(void)
1940 {
1941         scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1942                                            sizeof(struct scsi_data_buffer),
1943                                            0, 0, NULL);
1944         if (!scsi_sdb_cache) {
1945                 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1946                 return -ENOMEM;
1947         }
1948
1949         return 0;
1950 }
1951
1952 void scsi_exit_queue(void)
1953 {
1954         kmem_cache_destroy(scsi_sense_cache);
1955         kmem_cache_destroy(scsi_sense_isadma_cache);
1956         kmem_cache_destroy(scsi_sdb_cache);
1957 }
1958
1959 /**
1960  *      scsi_mode_select - issue a mode select
1961  *      @sdev:  SCSI device to be queried
1962  *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
1963  *      @sp:    Save page bit (0 == don't save, 1 == save)
1964  *      @modepage: mode page being requested
1965  *      @buffer: request buffer (may not be smaller than eight bytes)
1966  *      @len:   length of request buffer.
1967  *      @timeout: command timeout
1968  *      @retries: number of retries before failing
1969  *      @data: returns a structure abstracting the mode header data
1970  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
1971  *              must be SCSI_SENSE_BUFFERSIZE big.
1972  *
1973  *      Returns zero if successful; negative error number or scsi
1974  *      status on error
1975  *
1976  */
1977 int
1978 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1979                  unsigned char *buffer, int len, int timeout, int retries,
1980                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1981 {
1982         unsigned char cmd[10];
1983         unsigned char *real_buffer;
1984         int ret;
1985
1986         memset(cmd, 0, sizeof(cmd));
1987         cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1988
1989         if (sdev->use_10_for_ms) {
1990                 if (len > 65535)
1991                         return -EINVAL;
1992                 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1993                 if (!real_buffer)
1994                         return -ENOMEM;
1995                 memcpy(real_buffer + 8, buffer, len);
1996                 len += 8;
1997                 real_buffer[0] = 0;
1998                 real_buffer[1] = 0;
1999                 real_buffer[2] = data->medium_type;
2000                 real_buffer[3] = data->device_specific;
2001                 real_buffer[4] = data->longlba ? 0x01 : 0;
2002                 real_buffer[5] = 0;
2003                 real_buffer[6] = data->block_descriptor_length >> 8;
2004                 real_buffer[7] = data->block_descriptor_length;
2005
2006                 cmd[0] = MODE_SELECT_10;
2007                 cmd[7] = len >> 8;
2008                 cmd[8] = len;
2009         } else {
2010                 if (len > 255 || data->block_descriptor_length > 255 ||
2011                     data->longlba)
2012                         return -EINVAL;
2013
2014                 real_buffer = kmalloc(4 + len, GFP_KERNEL);
2015                 if (!real_buffer)
2016                         return -ENOMEM;
2017                 memcpy(real_buffer + 4, buffer, len);
2018                 len += 4;
2019                 real_buffer[0] = 0;
2020                 real_buffer[1] = data->medium_type;
2021                 real_buffer[2] = data->device_specific;
2022                 real_buffer[3] = data->block_descriptor_length;
2023                 
2024
2025                 cmd[0] = MODE_SELECT;
2026                 cmd[4] = len;
2027         }
2028
2029         ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2030                                sshdr, timeout, retries, NULL);
2031         kfree(real_buffer);
2032         return ret;
2033 }
2034 EXPORT_SYMBOL_GPL(scsi_mode_select);
2035
2036 /**
2037  *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2038  *      @sdev:  SCSI device to be queried
2039  *      @dbd:   set if mode sense will allow block descriptors to be returned
2040  *      @modepage: mode page being requested
2041  *      @buffer: request buffer (may not be smaller than eight bytes)
2042  *      @len:   length of request buffer.
2043  *      @timeout: command timeout
2044  *      @retries: number of retries before failing
2045  *      @data: returns a structure abstracting the mode header data
2046  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2047  *              must be SCSI_SENSE_BUFFERSIZE big.
2048  *
2049  *      Returns zero if unsuccessful, or the header offset (either 4
2050  *      or 8 depending on whether a six or ten byte command was
2051  *      issued) if successful.
2052  */
2053 int
2054 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2055                   unsigned char *buffer, int len, int timeout, int retries,
2056                   struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2057 {
2058         unsigned char cmd[12];
2059         int use_10_for_ms;
2060         int header_length;
2061         int result, retry_count = retries;
2062         struct scsi_sense_hdr my_sshdr;
2063
2064         memset(data, 0, sizeof(*data));
2065         memset(&cmd[0], 0, 12);
2066         cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
2067         cmd[2] = modepage;
2068
2069         /* caller might not be interested in sense, but we need it */
2070         if (!sshdr)
2071                 sshdr = &my_sshdr;
2072
2073  retry:
2074         use_10_for_ms = sdev->use_10_for_ms;
2075
2076         if (use_10_for_ms) {
2077                 if (len < 8)
2078                         len = 8;
2079
2080                 cmd[0] = MODE_SENSE_10;
2081                 cmd[8] = len;
2082                 header_length = 8;
2083         } else {
2084                 if (len < 4)
2085                         len = 4;
2086
2087                 cmd[0] = MODE_SENSE;
2088                 cmd[4] = len;
2089                 header_length = 4;
2090         }
2091
2092         memset(buffer, 0, len);
2093
2094         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2095                                   sshdr, timeout, retries, NULL);
2096
2097         /* This code looks awful: what it's doing is making sure an
2098          * ILLEGAL REQUEST sense return identifies the actual command
2099          * byte as the problem.  MODE_SENSE commands can return
2100          * ILLEGAL REQUEST if the code page isn't supported */
2101
2102         if (use_10_for_ms && !scsi_status_is_good(result) &&
2103             driver_byte(result) == DRIVER_SENSE) {
2104                 if (scsi_sense_valid(sshdr)) {
2105                         if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2106                             (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2107                                 /* 
2108                                  * Invalid command operation code
2109                                  */
2110                                 sdev->use_10_for_ms = 0;
2111                                 goto retry;
2112                         }
2113                 }
2114         }
2115
2116         if(scsi_status_is_good(result)) {
2117                 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2118                              (modepage == 6 || modepage == 8))) {
2119                         /* Initio breakage? */
2120                         header_length = 0;
2121                         data->length = 13;
2122                         data->medium_type = 0;
2123                         data->device_specific = 0;
2124                         data->longlba = 0;
2125                         data->block_descriptor_length = 0;
2126                 } else if(use_10_for_ms) {
2127                         data->length = buffer[0]*256 + buffer[1] + 2;
2128                         data->medium_type = buffer[2];
2129                         data->device_specific = buffer[3];
2130                         data->longlba = buffer[4] & 0x01;
2131                         data->block_descriptor_length = buffer[6]*256
2132                                 + buffer[7];
2133                 } else {
2134                         data->length = buffer[0] + 1;
2135                         data->medium_type = buffer[1];
2136                         data->device_specific = buffer[2];
2137                         data->block_descriptor_length = buffer[3];
2138                 }
2139                 data->header_length = header_length;
2140         } else if ((status_byte(result) == CHECK_CONDITION) &&
2141                    scsi_sense_valid(sshdr) &&
2142                    sshdr->sense_key == UNIT_ATTENTION && retry_count) {
2143                 retry_count--;
2144                 goto retry;
2145         }
2146
2147         return result;
2148 }
2149 EXPORT_SYMBOL(scsi_mode_sense);
2150
2151 /**
2152  *      scsi_test_unit_ready - test if unit is ready
2153  *      @sdev:  scsi device to change the state of.
2154  *      @timeout: command timeout
2155  *      @retries: number of retries before failing
2156  *      @sshdr: outpout pointer for decoded sense information.
2157  *
2158  *      Returns zero if unsuccessful or an error if TUR failed.  For
2159  *      removable media, UNIT_ATTENTION sets ->changed flag.
2160  **/
2161 int
2162 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2163                      struct scsi_sense_hdr *sshdr)
2164 {
2165         char cmd[] = {
2166                 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2167         };
2168         int result;
2169
2170         /* try to eat the UNIT_ATTENTION if there are enough retries */
2171         do {
2172                 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2173                                           timeout, 1, NULL);
2174                 if (sdev->removable && scsi_sense_valid(sshdr) &&
2175                     sshdr->sense_key == UNIT_ATTENTION)
2176                         sdev->changed = 1;
2177         } while (scsi_sense_valid(sshdr) &&
2178                  sshdr->sense_key == UNIT_ATTENTION && --retries);
2179
2180         return result;
2181 }
2182 EXPORT_SYMBOL(scsi_test_unit_ready);
2183
2184 /**
2185  *      scsi_device_set_state - Take the given device through the device state model.
2186  *      @sdev:  scsi device to change the state of.
2187  *      @state: state to change to.
2188  *
2189  *      Returns zero if successful or an error if the requested
2190  *      transition is illegal.
2191  */
2192 int
2193 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2194 {
2195         enum scsi_device_state oldstate = sdev->sdev_state;
2196
2197         if (state == oldstate)
2198                 return 0;
2199
2200         switch (state) {
2201         case SDEV_CREATED:
2202                 switch (oldstate) {
2203                 case SDEV_CREATED_BLOCK:
2204                         break;
2205                 default:
2206                         goto illegal;
2207                 }
2208                 break;
2209                         
2210         case SDEV_RUNNING:
2211                 switch (oldstate) {
2212                 case SDEV_CREATED:
2213                 case SDEV_OFFLINE:
2214                 case SDEV_TRANSPORT_OFFLINE:
2215                 case SDEV_QUIESCE:
2216                 case SDEV_BLOCK:
2217                         break;
2218                 default:
2219                         goto illegal;
2220                 }
2221                 break;
2222
2223         case SDEV_QUIESCE:
2224                 switch (oldstate) {
2225                 case SDEV_RUNNING:
2226                 case SDEV_OFFLINE:
2227                 case SDEV_TRANSPORT_OFFLINE:
2228                         break;
2229                 default:
2230                         goto illegal;
2231                 }
2232                 break;
2233
2234         case SDEV_OFFLINE:
2235         case SDEV_TRANSPORT_OFFLINE:
2236                 switch (oldstate) {
2237                 case SDEV_CREATED:
2238                 case SDEV_RUNNING:
2239                 case SDEV_QUIESCE:
2240                 case SDEV_BLOCK:
2241                         break;
2242                 default:
2243                         goto illegal;
2244                 }
2245                 break;
2246
2247         case SDEV_BLOCK:
2248                 switch (oldstate) {
2249                 case SDEV_RUNNING:
2250                 case SDEV_CREATED_BLOCK:
2251                 case SDEV_OFFLINE:
2252                         break;
2253                 default:
2254                         goto illegal;
2255                 }
2256                 break;
2257
2258         case SDEV_CREATED_BLOCK:
2259                 switch (oldstate) {
2260                 case SDEV_CREATED:
2261                         break;
2262                 default:
2263                         goto illegal;
2264                 }
2265                 break;
2266
2267         case SDEV_CANCEL:
2268                 switch (oldstate) {
2269                 case SDEV_CREATED:
2270                 case SDEV_RUNNING:
2271                 case SDEV_QUIESCE:
2272                 case SDEV_OFFLINE:
2273                 case SDEV_TRANSPORT_OFFLINE:
2274                         break;
2275                 default:
2276                         goto illegal;
2277                 }
2278                 break;
2279
2280         case SDEV_DEL:
2281                 switch (oldstate) {
2282                 case SDEV_CREATED:
2283                 case SDEV_RUNNING:
2284                 case SDEV_OFFLINE:
2285                 case SDEV_TRANSPORT_OFFLINE:
2286                 case SDEV_CANCEL:
2287                 case SDEV_BLOCK:
2288                 case SDEV_CREATED_BLOCK:
2289                         break;
2290                 default:
2291                         goto illegal;
2292                 }
2293                 break;
2294
2295         }
2296         sdev->sdev_state = state;
2297         return 0;
2298
2299  illegal:
2300         SCSI_LOG_ERROR_RECOVERY(1,
2301                                 sdev_printk(KERN_ERR, sdev,
2302                                             "Illegal state transition %s->%s",
2303                                             scsi_device_state_name(oldstate),
2304                                             scsi_device_state_name(state))
2305                                 );
2306         return -EINVAL;
2307 }
2308 EXPORT_SYMBOL(scsi_device_set_state);
2309
2310 /**
2311  *      sdev_evt_emit - emit a single SCSI device uevent
2312  *      @sdev: associated SCSI device
2313  *      @evt: event to emit
2314  *
2315  *      Send a single uevent (scsi_event) to the associated scsi_device.
2316  */
2317 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2318 {
2319         int idx = 0;
2320         char *envp[3];
2321
2322         switch (evt->evt_type) {
2323         case SDEV_EVT_MEDIA_CHANGE:
2324                 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2325                 break;
2326         case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2327                 scsi_rescan_device(&sdev->sdev_gendev);
2328                 envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
2329                 break;
2330         case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2331                 envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
2332                 break;
2333         case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2334                envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
2335                 break;
2336         case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2337                 envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
2338                 break;
2339         case SDEV_EVT_LUN_CHANGE_REPORTED:
2340                 envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
2341                 break;
2342         case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2343                 envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
2344                 break;
2345         case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2346                 envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED";
2347                 break;
2348         default:
2349                 /* do nothing */
2350                 break;
2351         }
2352
2353         envp[idx++] = NULL;
2354
2355         kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2356 }
2357
2358 /**
2359  *      sdev_evt_thread - send a uevent for each scsi event
2360  *      @work: work struct for scsi_device
2361  *
2362  *      Dispatch queued events to their associated scsi_device kobjects
2363  *      as uevents.
2364  */
2365 void scsi_evt_thread(struct work_struct *work)
2366 {
2367         struct scsi_device *sdev;
2368         enum scsi_device_event evt_type;
2369         LIST_HEAD(event_list);
2370
2371         sdev = container_of(work, struct scsi_device, event_work);
2372
2373         for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
2374                 if (test_and_clear_bit(evt_type, sdev->pending_events))
2375                         sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
2376
2377         while (1) {
2378                 struct scsi_event *evt;
2379                 struct list_head *this, *tmp;
2380                 unsigned long flags;
2381
2382                 spin_lock_irqsave(&sdev->list_lock, flags);
2383                 list_splice_init(&sdev->event_list, &event_list);
2384                 spin_unlock_irqrestore(&sdev->list_lock, flags);
2385
2386                 if (list_empty(&event_list))
2387                         break;
2388
2389                 list_for_each_safe(this, tmp, &event_list) {
2390                         evt = list_entry(this, struct scsi_event, node);
2391                         list_del(&evt->node);
2392                         scsi_evt_emit(sdev, evt);
2393                         kfree(evt);
2394                 }
2395         }
2396 }
2397
2398 /**
2399  *      sdev_evt_send - send asserted event to uevent thread
2400  *      @sdev: scsi_device event occurred on
2401  *      @evt: event to send
2402  *
2403  *      Assert scsi device event asynchronously.
2404  */
2405 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2406 {
2407         unsigned long flags;
2408
2409 #if 0
2410         /* FIXME: currently this check eliminates all media change events
2411          * for polled devices.  Need to update to discriminate between AN
2412          * and polled events */
2413         if (!test_bit(evt->evt_type, sdev->supported_events)) {
2414                 kfree(evt);
2415                 return;
2416         }
2417 #endif
2418
2419         spin_lock_irqsave(&sdev->list_lock, flags);
2420         list_add_tail(&evt->node, &sdev->event_list);
2421         schedule_work(&sdev->event_work);
2422         spin_unlock_irqrestore(&sdev->list_lock, flags);
2423 }
2424 EXPORT_SYMBOL_GPL(sdev_evt_send);
2425
2426 /**
2427  *      sdev_evt_alloc - allocate a new scsi event
2428  *      @evt_type: type of event to allocate
2429  *      @gfpflags: GFP flags for allocation
2430  *
2431  *      Allocates and returns a new scsi_event.
2432  */
2433 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2434                                   gfp_t gfpflags)
2435 {
2436         struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2437         if (!evt)
2438                 return NULL;
2439
2440         evt->evt_type = evt_type;
2441         INIT_LIST_HEAD(&evt->node);
2442
2443         /* evt_type-specific initialization, if any */
2444         switch (evt_type) {
2445         case SDEV_EVT_MEDIA_CHANGE:
2446         case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2447         case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2448         case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2449         case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2450         case SDEV_EVT_LUN_CHANGE_REPORTED:
2451         case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2452         case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2453         default:
2454                 /* do nothing */
2455                 break;
2456         }
2457
2458         return evt;
2459 }
2460 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2461
2462 /**
2463  *      sdev_evt_send_simple - send asserted event to uevent thread
2464  *      @sdev: scsi_device event occurred on
2465  *      @evt_type: type of event to send
2466  *      @gfpflags: GFP flags for allocation
2467  *
2468  *      Assert scsi device event asynchronously, given an event type.
2469  */
2470 void sdev_evt_send_simple(struct scsi_device *sdev,
2471                           enum scsi_device_event evt_type, gfp_t gfpflags)
2472 {
2473         struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2474         if (!evt) {
2475                 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2476                             evt_type);
2477                 return;
2478         }
2479
2480         sdev_evt_send(sdev, evt);
2481 }
2482 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2483
2484 /**
2485  *      scsi_device_quiesce - Block user issued commands.
2486  *      @sdev:  scsi device to quiesce.
2487  *
2488  *      This works by trying to transition to the SDEV_QUIESCE state
2489  *      (which must be a legal transition).  When the device is in this
2490  *      state, only special requests will be accepted, all others will
2491  *      be deferred.  Since special requests may also be requeued requests,
2492  *      a successful return doesn't guarantee the device will be 
2493  *      totally quiescent.
2494  *
2495  *      Must be called with user context, may sleep.
2496  *
2497  *      Returns zero if unsuccessful or an error if not.
2498  */
2499 int
2500 scsi_device_quiesce(struct scsi_device *sdev)
2501 {
2502         struct request_queue *q = sdev->request_queue;
2503         int err;
2504
2505         /*
2506          * It is allowed to call scsi_device_quiesce() multiple times from
2507          * the same context but concurrent scsi_device_quiesce() calls are
2508          * not allowed.
2509          */
2510         WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current);
2511
2512         if (sdev->quiesced_by == current)
2513                 return 0;
2514
2515         blk_set_pm_only(q);
2516
2517         blk_mq_freeze_queue(q);
2518         /*
2519          * Ensure that the effect of blk_set_pm_only() will be visible
2520          * for percpu_ref_tryget() callers that occur after the queue
2521          * unfreeze even if the queue was already frozen before this function
2522          * was called. See also https://lwn.net/Articles/573497/.
2523          */
2524         synchronize_rcu();
2525         blk_mq_unfreeze_queue(q);
2526
2527         mutex_lock(&sdev->state_mutex);
2528         err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2529         if (err == 0)
2530                 sdev->quiesced_by = current;
2531         else
2532                 blk_clear_pm_only(q);
2533         mutex_unlock(&sdev->state_mutex);
2534
2535         return err;
2536 }
2537 EXPORT_SYMBOL(scsi_device_quiesce);
2538
2539 /**
2540  *      scsi_device_resume - Restart user issued commands to a quiesced device.
2541  *      @sdev:  scsi device to resume.
2542  *
2543  *      Moves the device from quiesced back to running and restarts the
2544  *      queues.
2545  *
2546  *      Must be called with user context, may sleep.
2547  */
2548 void scsi_device_resume(struct scsi_device *sdev)
2549 {
2550         /* check if the device state was mutated prior to resume, and if
2551          * so assume the state is being managed elsewhere (for example
2552          * device deleted during suspend)
2553          */
2554         mutex_lock(&sdev->state_mutex);
2555         if (sdev->quiesced_by) {
2556                 sdev->quiesced_by = NULL;
2557                 blk_clear_pm_only(sdev->request_queue);
2558         }
2559         if (sdev->sdev_state == SDEV_QUIESCE)
2560                 scsi_device_set_state(sdev, SDEV_RUNNING);
2561         mutex_unlock(&sdev->state_mutex);
2562 }
2563 EXPORT_SYMBOL(scsi_device_resume);
2564
2565 static void
2566 device_quiesce_fn(struct scsi_device *sdev, void *data)
2567 {
2568         scsi_device_quiesce(sdev);
2569 }
2570
2571 void
2572 scsi_target_quiesce(struct scsi_target *starget)
2573 {
2574         starget_for_each_device(starget, NULL, device_quiesce_fn);
2575 }
2576 EXPORT_SYMBOL(scsi_target_quiesce);
2577
2578 static void
2579 device_resume_fn(struct scsi_device *sdev, void *data)
2580 {
2581         scsi_device_resume(sdev);
2582 }
2583
2584 void
2585 scsi_target_resume(struct scsi_target *starget)
2586 {
2587         starget_for_each_device(starget, NULL, device_resume_fn);
2588 }
2589 EXPORT_SYMBOL(scsi_target_resume);
2590
2591 /**
2592  * scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state
2593  * @sdev: device to block
2594  *
2595  * Pause SCSI command processing on the specified device. Does not sleep.
2596  *
2597  * Returns zero if successful or a negative error code upon failure.
2598  *
2599  * Notes:
2600  * This routine transitions the device to the SDEV_BLOCK state (which must be
2601  * a legal transition). When the device is in this state, command processing
2602  * is paused until the device leaves the SDEV_BLOCK state. See also
2603  * scsi_internal_device_unblock_nowait().
2604  */
2605 int scsi_internal_device_block_nowait(struct scsi_device *sdev)
2606 {
2607         struct request_queue *q = sdev->request_queue;
2608         int err = 0;
2609
2610         err = scsi_device_set_state(sdev, SDEV_BLOCK);
2611         if (err) {
2612                 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2613
2614                 if (err)
2615                         return err;
2616         }
2617
2618         /* 
2619          * The device has transitioned to SDEV_BLOCK.  Stop the
2620          * block layer from calling the midlayer with this device's
2621          * request queue. 
2622          */
2623         blk_mq_quiesce_queue_nowait(q);
2624         return 0;
2625 }
2626 EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
2627
2628 /**
2629  * scsi_internal_device_block - try to transition to the SDEV_BLOCK state
2630  * @sdev: device to block
2631  *
2632  * Pause SCSI command processing on the specified device and wait until all
2633  * ongoing scsi_request_fn() / scsi_queue_rq() calls have finished. May sleep.
2634  *
2635  * Returns zero if successful or a negative error code upon failure.
2636  *
2637  * Note:
2638  * This routine transitions the device to the SDEV_BLOCK state (which must be
2639  * a legal transition). When the device is in this state, command processing
2640  * is paused until the device leaves the SDEV_BLOCK state. See also
2641  * scsi_internal_device_unblock().
2642  *
2643  * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
2644  * scsi_internal_device_block() has blocked a SCSI device and also
2645  * remove the rport mutex lock and unlock calls from srp_queuecommand().
2646  */
2647 static int scsi_internal_device_block(struct scsi_device *sdev)
2648 {
2649         struct request_queue *q = sdev->request_queue;
2650         int err;
2651
2652         mutex_lock(&sdev->state_mutex);
2653         err = scsi_internal_device_block_nowait(sdev);
2654         if (err == 0)
2655                 blk_mq_quiesce_queue(q);
2656         mutex_unlock(&sdev->state_mutex);
2657
2658         return err;
2659 }
2660  
2661 void scsi_start_queue(struct scsi_device *sdev)
2662 {
2663         struct request_queue *q = sdev->request_queue;
2664
2665         blk_mq_unquiesce_queue(q);
2666 }
2667
2668 /**
2669  * scsi_internal_device_unblock_nowait - resume a device after a block request
2670  * @sdev:       device to resume
2671  * @new_state:  state to set the device to after unblocking
2672  *
2673  * Restart the device queue for a previously suspended SCSI device. Does not
2674  * sleep.
2675  *
2676  * Returns zero if successful or a negative error code upon failure.
2677  *
2678  * Notes:
2679  * This routine transitions the device to the SDEV_RUNNING state or to one of
2680  * the offline states (which must be a legal transition) allowing the midlayer
2681  * to goose the queue for this device.
2682  */
2683 int scsi_internal_device_unblock_nowait(struct scsi_device *sdev,
2684                                         enum scsi_device_state new_state)
2685 {
2686         /*
2687          * Try to transition the scsi device to SDEV_RUNNING or one of the
2688          * offlined states and goose the device queue if successful.
2689          */
2690         switch (sdev->sdev_state) {
2691         case SDEV_BLOCK:
2692         case SDEV_TRANSPORT_OFFLINE:
2693                 sdev->sdev_state = new_state;
2694                 break;
2695         case SDEV_CREATED_BLOCK:
2696                 if (new_state == SDEV_TRANSPORT_OFFLINE ||
2697                     new_state == SDEV_OFFLINE)
2698                         sdev->sdev_state = new_state;
2699                 else
2700                         sdev->sdev_state = SDEV_CREATED;
2701                 break;
2702         case SDEV_CANCEL:
2703         case SDEV_OFFLINE:
2704                 break;
2705         default:
2706                 return -EINVAL;
2707         }
2708         scsi_start_queue(sdev);
2709
2710         return 0;
2711 }
2712 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
2713
2714 /**
2715  * scsi_internal_device_unblock - resume a device after a block request
2716  * @sdev:       device to resume
2717  * @new_state:  state to set the device to after unblocking
2718  *
2719  * Restart the device queue for a previously suspended SCSI device. May sleep.
2720  *
2721  * Returns zero if successful or a negative error code upon failure.
2722  *
2723  * Notes:
2724  * This routine transitions the device to the SDEV_RUNNING state or to one of
2725  * the offline states (which must be a legal transition) allowing the midlayer
2726  * to goose the queue for this device.
2727  */
2728 static int scsi_internal_device_unblock(struct scsi_device *sdev,
2729                                         enum scsi_device_state new_state)
2730 {
2731         int ret;
2732
2733         mutex_lock(&sdev->state_mutex);
2734         ret = scsi_internal_device_unblock_nowait(sdev, new_state);
2735         mutex_unlock(&sdev->state_mutex);
2736
2737         return ret;
2738 }
2739
2740 static void
2741 device_block(struct scsi_device *sdev, void *data)
2742 {
2743         scsi_internal_device_block(sdev);
2744 }
2745
2746 static int
2747 target_block(struct device *dev, void *data)
2748 {
2749         if (scsi_is_target_device(dev))
2750                 starget_for_each_device(to_scsi_target(dev), NULL,
2751                                         device_block);
2752         return 0;
2753 }
2754
2755 void
2756 scsi_target_block(struct device *dev)
2757 {
2758         if (scsi_is_target_device(dev))
2759                 starget_for_each_device(to_scsi_target(dev), NULL,
2760                                         device_block);
2761         else
2762                 device_for_each_child(dev, NULL, target_block);
2763 }
2764 EXPORT_SYMBOL_GPL(scsi_target_block);
2765
2766 static void
2767 device_unblock(struct scsi_device *sdev, void *data)
2768 {
2769         scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
2770 }
2771
2772 static int
2773 target_unblock(struct device *dev, void *data)
2774 {
2775         if (scsi_is_target_device(dev))
2776                 starget_for_each_device(to_scsi_target(dev), data,
2777                                         device_unblock);
2778         return 0;
2779 }
2780
2781 void
2782 scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
2783 {
2784         if (scsi_is_target_device(dev))
2785                 starget_for_each_device(to_scsi_target(dev), &new_state,
2786                                         device_unblock);
2787         else
2788                 device_for_each_child(dev, &new_state, target_unblock);
2789 }
2790 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2791
2792 /**
2793  * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2794  * @sgl:        scatter-gather list
2795  * @sg_count:   number of segments in sg
2796  * @offset:     offset in bytes into sg, on return offset into the mapped area
2797  * @len:        bytes to map, on return number of bytes mapped
2798  *
2799  * Returns virtual address of the start of the mapped page
2800  */
2801 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2802                           size_t *offset, size_t *len)
2803 {
2804         int i;
2805         size_t sg_len = 0, len_complete = 0;
2806         struct scatterlist *sg;
2807         struct page *page;
2808
2809         WARN_ON(!irqs_disabled());
2810
2811         for_each_sg(sgl, sg, sg_count, i) {
2812                 len_complete = sg_len; /* Complete sg-entries */
2813                 sg_len += sg->length;
2814                 if (sg_len > *offset)
2815                         break;
2816         }
2817
2818         if (unlikely(i == sg_count)) {
2819                 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2820                         "elements %d\n",
2821                        __func__, sg_len, *offset, sg_count);
2822                 WARN_ON(1);
2823                 return NULL;
2824         }
2825
2826         /* Offset starting from the beginning of first page in this sg-entry */
2827         *offset = *offset - len_complete + sg->offset;
2828
2829         /* Assumption: contiguous pages can be accessed as "page + i" */
2830         page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2831         *offset &= ~PAGE_MASK;
2832
2833         /* Bytes in this sg-entry from *offset to the end of the page */
2834         sg_len = PAGE_SIZE - *offset;
2835         if (*len > sg_len)
2836                 *len = sg_len;
2837
2838         return kmap_atomic(page);
2839 }
2840 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2841
2842 /**
2843  * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2844  * @virt:       virtual address to be unmapped
2845  */
2846 void scsi_kunmap_atomic_sg(void *virt)
2847 {
2848         kunmap_atomic(virt);
2849 }
2850 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
2851
2852 void sdev_disable_disk_events(struct scsi_device *sdev)
2853 {
2854         atomic_inc(&sdev->disk_events_disable_depth);
2855 }
2856 EXPORT_SYMBOL(sdev_disable_disk_events);
2857
2858 void sdev_enable_disk_events(struct scsi_device *sdev)
2859 {
2860         if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
2861                 return;
2862         atomic_dec(&sdev->disk_events_disable_depth);
2863 }
2864 EXPORT_SYMBOL(sdev_enable_disk_events);
2865
2866 /**
2867  * scsi_vpd_lun_id - return a unique device identification
2868  * @sdev: SCSI device
2869  * @id:   buffer for the identification
2870  * @id_len:  length of the buffer
2871  *
2872  * Copies a unique device identification into @id based
2873  * on the information in the VPD page 0x83 of the device.
2874  * The string will be formatted as a SCSI name string.
2875  *
2876  * Returns the length of the identification or error on failure.
2877  * If the identifier is longer than the supplied buffer the actual
2878  * identifier length is returned and the buffer is not zero-padded.
2879  */
2880 int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
2881 {
2882         u8 cur_id_type = 0xff;
2883         u8 cur_id_size = 0;
2884         const unsigned char *d, *cur_id_str;
2885         const struct scsi_vpd *vpd_pg83;
2886         int id_size = -EINVAL;
2887
2888         rcu_read_lock();
2889         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
2890         if (!vpd_pg83) {
2891                 rcu_read_unlock();
2892                 return -ENXIO;
2893         }
2894
2895         /*
2896          * Look for the correct descriptor.
2897          * Order of preference for lun descriptor:
2898          * - SCSI name string
2899          * - NAA IEEE Registered Extended
2900          * - EUI-64 based 16-byte
2901          * - EUI-64 based 12-byte
2902          * - NAA IEEE Registered
2903          * - NAA IEEE Extended
2904          * - T10 Vendor ID
2905          * as longer descriptors reduce the likelyhood
2906          * of identification clashes.
2907          */
2908
2909         /* The id string must be at least 20 bytes + terminating NULL byte */
2910         if (id_len < 21) {
2911                 rcu_read_unlock();
2912                 return -EINVAL;
2913         }
2914
2915         memset(id, 0, id_len);
2916         d = vpd_pg83->data + 4;
2917         while (d < vpd_pg83->data + vpd_pg83->len) {
2918                 /* Skip designators not referring to the LUN */
2919                 if ((d[1] & 0x30) != 0x00)
2920                         goto next_desig;
2921
2922                 switch (d[1] & 0xf) {
2923                 case 0x1:
2924                         /* T10 Vendor ID */
2925                         if (cur_id_size > d[3])
2926                                 break;
2927                         /* Prefer anything */
2928                         if (cur_id_type > 0x01 && cur_id_type != 0xff)
2929                                 break;
2930                         cur_id_size = d[3];
2931                         if (cur_id_size + 4 > id_len)
2932                                 cur_id_size = id_len - 4;
2933                         cur_id_str = d + 4;
2934                         cur_id_type = d[1] & 0xf;
2935                         id_size = snprintf(id, id_len, "t10.%*pE",
2936                                            cur_id_size, cur_id_str);
2937                         break;
2938                 case 0x2:
2939                         /* EUI-64 */
2940                         if (cur_id_size > d[3])
2941                                 break;
2942                         /* Prefer NAA IEEE Registered Extended */
2943                         if (cur_id_type == 0x3 &&
2944                             cur_id_size == d[3])
2945                                 break;
2946                         cur_id_size = d[3];
2947                         cur_id_str = d + 4;
2948                         cur_id_type = d[1] & 0xf;
2949                         switch (cur_id_size) {
2950                         case 8:
2951                                 id_size = snprintf(id, id_len,
2952                                                    "eui.%8phN",
2953                                                    cur_id_str);
2954                                 break;
2955                         case 12:
2956                                 id_size = snprintf(id, id_len,
2957                                                    "eui.%12phN",
2958                                                    cur_id_str);
2959                                 break;
2960                         case 16:
2961                                 id_size = snprintf(id, id_len,
2962                                                    "eui.%16phN",
2963                                                    cur_id_str);
2964                                 break;
2965                         default:
2966                                 cur_id_size = 0;
2967                                 break;
2968                         }
2969                         break;
2970                 case 0x3:
2971                         /* NAA */
2972                         if (cur_id_size > d[3])
2973                                 break;
2974                         cur_id_size = d[3];
2975                         cur_id_str = d + 4;
2976                         cur_id_type = d[1] & 0xf;
2977                         switch (cur_id_size) {
2978                         case 8:
2979                                 id_size = snprintf(id, id_len,
2980                                                    "naa.%8phN",
2981                                                    cur_id_str);
2982                                 break;
2983                         case 16:
2984                                 id_size = snprintf(id, id_len,
2985                                                    "naa.%16phN",
2986                                                    cur_id_str);
2987                                 break;
2988                         default:
2989                                 cur_id_size = 0;
2990                                 break;
2991                         }
2992                         break;
2993                 case 0x8:
2994                         /* SCSI name string */
2995                         if (cur_id_size + 4 > d[3])
2996                                 break;
2997                         /* Prefer others for truncated descriptor */
2998                         if (cur_id_size && d[3] > id_len)
2999                                 break;
3000                         cur_id_size = id_size = d[3];
3001                         cur_id_str = d + 4;
3002                         cur_id_type = d[1] & 0xf;
3003                         if (cur_id_size >= id_len)
3004                                 cur_id_size = id_len - 1;
3005                         memcpy(id, cur_id_str, cur_id_size);
3006                         /* Decrease priority for truncated descriptor */
3007                         if (cur_id_size != id_size)
3008                                 cur_id_size = 6;
3009                         break;
3010                 default:
3011                         break;
3012                 }
3013 next_desig:
3014                 d += d[3] + 4;
3015         }
3016         rcu_read_unlock();
3017
3018         return id_size;
3019 }
3020 EXPORT_SYMBOL(scsi_vpd_lun_id);
3021
3022 /*
3023  * scsi_vpd_tpg_id - return a target port group identifier
3024  * @sdev: SCSI device
3025  *
3026  * Returns the Target Port Group identifier from the information
3027  * froom VPD page 0x83 of the device.
3028  *
3029  * Returns the identifier or error on failure.
3030  */
3031 int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
3032 {
3033         const unsigned char *d;
3034         const struct scsi_vpd *vpd_pg83;
3035         int group_id = -EAGAIN, rel_port = -1;
3036
3037         rcu_read_lock();
3038         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3039         if (!vpd_pg83) {
3040                 rcu_read_unlock();
3041                 return -ENXIO;
3042         }
3043
3044         d = vpd_pg83->data + 4;
3045         while (d < vpd_pg83->data + vpd_pg83->len) {
3046                 switch (d[1] & 0xf) {
3047                 case 0x4:
3048                         /* Relative target port */
3049                         rel_port = get_unaligned_be16(&d[6]);
3050                         break;
3051                 case 0x5:
3052                         /* Target port group */
3053                         group_id = get_unaligned_be16(&d[6]);
3054                         break;
3055                 default:
3056                         break;
3057                 }
3058                 d += d[3] + 4;
3059         }
3060         rcu_read_unlock();
3061
3062         if (group_id >= 0 && rel_id && rel_port != -1)
3063                 *rel_id = rel_port;
3064
3065         return group_id;
3066 }
3067 EXPORT_SYMBOL(scsi_vpd_tpg_id);