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
42static struct kmem_cache *scsi_sdb_cache;
43static struct kmem_cache *scsi_sense_cache;
44static struct kmem_cache *scsi_sense_isadma_cache;
45static DEFINE_MUTEX(scsi_sense_cache_mutex);
46
47static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
48
49static inline struct kmem_cache *
50scsi_select_sense_cache(bool unchecked_isa_dma)
51{
52 return unchecked_isa_dma ? scsi_sense_isadma_cache : scsi_sense_cache;
53}
54
55static 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
62static 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
69int 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
106static void
107scsi_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
142static 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 */
168static 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 */
226void 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 */
250int __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}
304EXPORT_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 */
317static 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 */
334static 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
349void 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
362static 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 */
374static 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
413static 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
422static 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
433static 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
445static 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 */
516static 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
528void 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
538void 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
546static 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
556static 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
564static 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 */
572static 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 */
634static 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. */
666static 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. */
674static 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 */
836static 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 */
933void 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
986static 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 */
1020blk_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;
1064out_free_sgtables:
1065 scsi_mq_free_sgtables(cmd);
1066 return ret;
1067}
1068EXPORT_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 */
1081static 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 */
1092void 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 */
1106void 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. */
1121void 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
1152static 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 */
1184static 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
1200static 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
1218static blk_status_t
1219scsi_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 */
1268static 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;
1291out_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 */
1300static 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
1340starved:
1341 spin_lock_irq(shost->host_lock);
1342 list_move_tail(&sdev->starved_entry, &shost->starved_list);
1343 spin_unlock_irq(shost->host_lock);
1344out_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 */
1355static 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
1395starved:
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);
1400out_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 */
1417static 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
1439static 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 */
1485static 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. */
1560static 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
1566static 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
1594static 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
1610static 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
1619static 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
1631out_put_device:
1632 put_device(&sdev->sdev_gendev);
1633out:
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
1639static 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
1693out_dec_host_busy:
1694 scsi_dec_host_busy(shost);
1695out_dec_target_busy:
1696 if (scsi_target(sdev)->can_queue > 0)
1697 atomic_dec(&scsi_target(sdev)->target_busy);
1698out_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 /*
1710 * Make sure to release all allocated ressources when
1711 * we hit an error, as we will never see this command
1712 * again.
1713 */
1714 if (req->rq_flags & RQF_DONTPREP)
1715 scsi_mq_uninit_cmd(cmd);
1716 break;
1717 }
1718 return ret;
1719}
1720
1721static enum blk_eh_timer_return scsi_timeout(struct request *req,
1722 bool reserved)
1723{
1724 if (reserved)
1725 return BLK_EH_RESET_TIMER;
1726 return scsi_times_out(req);
1727}
1728
1729static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
1730 unsigned int hctx_idx, unsigned int numa_node)
1731{
1732 struct Scsi_Host *shost = set->driver_data;
1733 const bool unchecked_isa_dma = shost->unchecked_isa_dma;
1734 struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1735 struct scatterlist *sg;
1736
1737 if (unchecked_isa_dma)
1738 cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
1739 cmd->sense_buffer = scsi_alloc_sense_buffer(unchecked_isa_dma,
1740 GFP_KERNEL, numa_node);
1741 if (!cmd->sense_buffer)
1742 return -ENOMEM;
1743 cmd->req.sense = cmd->sense_buffer;
1744
1745 if (scsi_host_get_prot(shost)) {
1746 sg = (void *)cmd + sizeof(struct scsi_cmnd) +
1747 shost->hostt->cmd_size;
1748 cmd->prot_sdb = (void *)sg + scsi_mq_sgl_size(shost);
1749 }
1750
1751 return 0;
1752}
1753
1754static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
1755 unsigned int hctx_idx)
1756{
1757 struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1758
1759 scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,
1760 cmd->sense_buffer);
1761}
1762
1763static int scsi_map_queues(struct blk_mq_tag_set *set)
1764{
1765 struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
1766
1767 if (shost->hostt->map_queues)
1768 return shost->hostt->map_queues(shost);
1769 return blk_mq_map_queues(&set->map[0]);
1770}
1771
1772void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
1773{
1774 struct device *dev = shost->dma_dev;
1775
1776 /*
1777 * this limit is imposed by hardware restrictions
1778 */
1779 blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1780 SG_MAX_SEGMENTS));
1781
1782 if (scsi_host_prot_dma(shost)) {
1783 shost->sg_prot_tablesize =
1784 min_not_zero(shost->sg_prot_tablesize,
1785 (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1786 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1787 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1788 }
1789
1790 blk_queue_max_hw_sectors(q, shost->max_sectors);
1791 if (shost->unchecked_isa_dma)
1792 blk_queue_bounce_limit(q, BLK_BOUNCE_ISA);
1793 blk_queue_segment_boundary(q, shost->dma_boundary);
1794 dma_set_seg_boundary(dev, shost->dma_boundary);
1795
1796 blk_queue_max_segment_size(q, shost->max_segment_size);
1797 dma_set_max_seg_size(dev, shost->max_segment_size);
1798
1799 /*
1800 * Set a reasonable default alignment: The larger of 32-byte (dword),
1801 * which is a common minimum for HBAs, and the minimum DMA alignment,
1802 * which is set by the platform.
1803 *
1804 * Devices that require a bigger alignment can increase it later.
1805 */
1806 blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
1807}
1808EXPORT_SYMBOL_GPL(__scsi_init_queue);
1809
1810static const struct blk_mq_ops scsi_mq_ops = {
1811 .get_budget = scsi_mq_get_budget,
1812 .put_budget = scsi_mq_put_budget,
1813 .queue_rq = scsi_queue_rq,
1814 .complete = scsi_softirq_done,
1815 .timeout = scsi_timeout,
1816#ifdef CONFIG_BLK_DEBUG_FS
1817 .show_rq = scsi_show_rq,
1818#endif
1819 .init_request = scsi_mq_init_request,
1820 .exit_request = scsi_mq_exit_request,
1821 .initialize_rq_fn = scsi_initialize_rq,
1822 .busy = scsi_mq_lld_busy,
1823 .map_queues = scsi_map_queues,
1824};
1825
1826struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
1827{
1828 sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set);
1829 if (IS_ERR(sdev->request_queue))
1830 return NULL;
1831
1832 sdev->request_queue->queuedata = sdev;
1833 __scsi_init_queue(sdev->host, sdev->request_queue);
1834 blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, sdev->request_queue);
1835 return sdev->request_queue;
1836}
1837
1838int scsi_mq_setup_tags(struct Scsi_Host *shost)
1839{
1840 unsigned int cmd_size, sgl_size;
1841
1842 sgl_size = scsi_mq_sgl_size(shost);
1843 cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
1844 if (scsi_host_get_prot(shost))
1845 cmd_size += sizeof(struct scsi_data_buffer) + sgl_size;
1846
1847 memset(&shost->tag_set, 0, sizeof(shost->tag_set));
1848 shost->tag_set.ops = &scsi_mq_ops;
1849 shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
1850 shost->tag_set.queue_depth = shost->can_queue;
1851 shost->tag_set.cmd_size = cmd_size;
1852 shost->tag_set.numa_node = NUMA_NO_NODE;
1853 shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1854 shost->tag_set.flags |=
1855 BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
1856 shost->tag_set.driver_data = shost;
1857
1858 return blk_mq_alloc_tag_set(&shost->tag_set);
1859}
1860
1861void scsi_mq_destroy_tags(struct Scsi_Host *shost)
1862{
1863 blk_mq_free_tag_set(&shost->tag_set);
1864}
1865
1866/**
1867 * scsi_device_from_queue - return sdev associated with a request_queue
1868 * @q: The request queue to return the sdev from
1869 *
1870 * Return the sdev associated with a request queue or NULL if the
1871 * request_queue does not reference a SCSI device.
1872 */
1873struct scsi_device *scsi_device_from_queue(struct request_queue *q)
1874{
1875 struct scsi_device *sdev = NULL;
1876
1877 if (q->mq_ops == &scsi_mq_ops)
1878 sdev = q->queuedata;
1879 if (!sdev || !get_device(&sdev->sdev_gendev))
1880 sdev = NULL;
1881
1882 return sdev;
1883}
1884EXPORT_SYMBOL_GPL(scsi_device_from_queue);
1885
1886/*
1887 * Function: scsi_block_requests()
1888 *
1889 * Purpose: Utility function used by low-level drivers to prevent further
1890 * commands from being queued to the device.
1891 *
1892 * Arguments: shost - Host in question
1893 *
1894 * Returns: Nothing
1895 *
1896 * Lock status: No locks are assumed held.
1897 *
1898 * Notes: There is no timer nor any other means by which the requests
1899 * get unblocked other than the low-level driver calling
1900 * scsi_unblock_requests().
1901 */
1902void scsi_block_requests(struct Scsi_Host *shost)
1903{
1904 shost->host_self_blocked = 1;
1905}
1906EXPORT_SYMBOL(scsi_block_requests);
1907
1908/*
1909 * Function: scsi_unblock_requests()
1910 *
1911 * Purpose: Utility function used by low-level drivers to allow further
1912 * commands from being queued to the device.
1913 *
1914 * Arguments: shost - Host in question
1915 *
1916 * Returns: Nothing
1917 *
1918 * Lock status: No locks are assumed held.
1919 *
1920 * Notes: There is no timer nor any other means by which the requests
1921 * get unblocked other than the low-level driver calling
1922 * scsi_unblock_requests().
1923 *
1924 * This is done as an API function so that changes to the
1925 * internals of the scsi mid-layer won't require wholesale
1926 * changes to drivers that use this feature.
1927 */
1928void scsi_unblock_requests(struct Scsi_Host *shost)
1929{
1930 shost->host_self_blocked = 0;
1931 scsi_run_host_queues(shost);
1932}
1933EXPORT_SYMBOL(scsi_unblock_requests);
1934
1935int __init scsi_init_queue(void)
1936{
1937 scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1938 sizeof(struct scsi_data_buffer),
1939 0, 0, NULL);
1940 if (!scsi_sdb_cache) {
1941 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1942 return -ENOMEM;
1943 }
1944
1945 return 0;
1946}
1947
1948void scsi_exit_queue(void)
1949{
1950 kmem_cache_destroy(scsi_sense_cache);
1951 kmem_cache_destroy(scsi_sense_isadma_cache);
1952 kmem_cache_destroy(scsi_sdb_cache);
1953}
1954
1955/**
1956 * scsi_mode_select - issue a mode select
1957 * @sdev: SCSI device to be queried
1958 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1959 * @sp: Save page bit (0 == don't save, 1 == save)
1960 * @modepage: mode page being requested
1961 * @buffer: request buffer (may not be smaller than eight bytes)
1962 * @len: length of request buffer.
1963 * @timeout: command timeout
1964 * @retries: number of retries before failing
1965 * @data: returns a structure abstracting the mode header data
1966 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1967 * must be SCSI_SENSE_BUFFERSIZE big.
1968 *
1969 * Returns zero if successful; negative error number or scsi
1970 * status on error
1971 *
1972 */
1973int
1974scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1975 unsigned char *buffer, int len, int timeout, int retries,
1976 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1977{
1978 unsigned char cmd[10];
1979 unsigned char *real_buffer;
1980 int ret;
1981
1982 memset(cmd, 0, sizeof(cmd));
1983 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1984
1985 if (sdev->use_10_for_ms) {
1986 if (len > 65535)
1987 return -EINVAL;
1988 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1989 if (!real_buffer)
1990 return -ENOMEM;
1991 memcpy(real_buffer + 8, buffer, len);
1992 len += 8;
1993 real_buffer[0] = 0;
1994 real_buffer[1] = 0;
1995 real_buffer[2] = data->medium_type;
1996 real_buffer[3] = data->device_specific;
1997 real_buffer[4] = data->longlba ? 0x01 : 0;
1998 real_buffer[5] = 0;
1999 real_buffer[6] = data->block_descriptor_length >> 8;
2000 real_buffer[7] = data->block_descriptor_length;
2001
2002 cmd[0] = MODE_SELECT_10;
2003 cmd[7] = len >> 8;
2004 cmd[8] = len;
2005 } else {
2006 if (len > 255 || data->block_descriptor_length > 255 ||
2007 data->longlba)
2008 return -EINVAL;
2009
2010 real_buffer = kmalloc(4 + len, GFP_KERNEL);
2011 if (!real_buffer)
2012 return -ENOMEM;
2013 memcpy(real_buffer + 4, buffer, len);
2014 len += 4;
2015 real_buffer[0] = 0;
2016 real_buffer[1] = data->medium_type;
2017 real_buffer[2] = data->device_specific;
2018 real_buffer[3] = data->block_descriptor_length;
2019
2020
2021 cmd[0] = MODE_SELECT;
2022 cmd[4] = len;
2023 }
2024
2025 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2026 sshdr, timeout, retries, NULL);
2027 kfree(real_buffer);
2028 return ret;
2029}
2030EXPORT_SYMBOL_GPL(scsi_mode_select);
2031
2032/**
2033 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2034 * @sdev: SCSI device to be queried
2035 * @dbd: set if mode sense will allow block descriptors to be returned
2036 * @modepage: mode page being requested
2037 * @buffer: request buffer (may not be smaller than eight bytes)
2038 * @len: length of request buffer.
2039 * @timeout: command timeout
2040 * @retries: number of retries before failing
2041 * @data: returns a structure abstracting the mode header data
2042 * @sshdr: place to put sense data (or NULL if no sense to be collected).
2043 * must be SCSI_SENSE_BUFFERSIZE big.
2044 *
2045 * Returns zero if unsuccessful, or the header offset (either 4
2046 * or 8 depending on whether a six or ten byte command was
2047 * issued) if successful.
2048 */
2049int
2050scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2051 unsigned char *buffer, int len, int timeout, int retries,
2052 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2053{
2054 unsigned char cmd[12];
2055 int use_10_for_ms;
2056 int header_length;
2057 int result, retry_count = retries;
2058 struct scsi_sense_hdr my_sshdr;
2059
2060 memset(data, 0, sizeof(*data));
2061 memset(&cmd[0], 0, 12);
2062 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
2063 cmd[2] = modepage;
2064
2065 /* caller might not be interested in sense, but we need it */
2066 if (!sshdr)
2067 sshdr = &my_sshdr;
2068
2069 retry:
2070 use_10_for_ms = sdev->use_10_for_ms;
2071
2072 if (use_10_for_ms) {
2073 if (len < 8)
2074 len = 8;
2075
2076 cmd[0] = MODE_SENSE_10;
2077 cmd[8] = len;
2078 header_length = 8;
2079 } else {
2080 if (len < 4)
2081 len = 4;
2082
2083 cmd[0] = MODE_SENSE;
2084 cmd[4] = len;
2085 header_length = 4;
2086 }
2087
2088 memset(buffer, 0, len);
2089
2090 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2091 sshdr, timeout, retries, NULL);
2092
2093 /* This code looks awful: what it's doing is making sure an
2094 * ILLEGAL REQUEST sense return identifies the actual command
2095 * byte as the problem. MODE_SENSE commands can return
2096 * ILLEGAL REQUEST if the code page isn't supported */
2097
2098 if (use_10_for_ms && !scsi_status_is_good(result) &&
2099 driver_byte(result) == DRIVER_SENSE) {
2100 if (scsi_sense_valid(sshdr)) {
2101 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2102 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2103 /*
2104 * Invalid command operation code
2105 */
2106 sdev->use_10_for_ms = 0;
2107 goto retry;
2108 }
2109 }
2110 }
2111
2112 if(scsi_status_is_good(result)) {
2113 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2114 (modepage == 6 || modepage == 8))) {
2115 /* Initio breakage? */
2116 header_length = 0;
2117 data->length = 13;
2118 data->medium_type = 0;
2119 data->device_specific = 0;
2120 data->longlba = 0;
2121 data->block_descriptor_length = 0;
2122 } else if(use_10_for_ms) {
2123 data->length = buffer[0]*256 + buffer[1] + 2;
2124 data->medium_type = buffer[2];
2125 data->device_specific = buffer[3];
2126 data->longlba = buffer[4] & 0x01;
2127 data->block_descriptor_length = buffer[6]*256
2128 + buffer[7];
2129 } else {
2130 data->length = buffer[0] + 1;
2131 data->medium_type = buffer[1];
2132 data->device_specific = buffer[2];
2133 data->block_descriptor_length = buffer[3];
2134 }
2135 data->header_length = header_length;
2136 } else if ((status_byte(result) == CHECK_CONDITION) &&
2137 scsi_sense_valid(sshdr) &&
2138 sshdr->sense_key == UNIT_ATTENTION && retry_count) {
2139 retry_count--;
2140 goto retry;
2141 }
2142
2143 return result;
2144}
2145EXPORT_SYMBOL(scsi_mode_sense);
2146
2147/**
2148 * scsi_test_unit_ready - test if unit is ready
2149 * @sdev: scsi device to change the state of.
2150 * @timeout: command timeout
2151 * @retries: number of retries before failing
2152 * @sshdr: outpout pointer for decoded sense information.
2153 *
2154 * Returns zero if unsuccessful or an error if TUR failed. For
2155 * removable media, UNIT_ATTENTION sets ->changed flag.
2156 **/
2157int
2158scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2159 struct scsi_sense_hdr *sshdr)
2160{
2161 char cmd[] = {
2162 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2163 };
2164 int result;
2165
2166 /* try to eat the UNIT_ATTENTION if there are enough retries */
2167 do {
2168 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2169 timeout, 1, NULL);
2170 if (sdev->removable && scsi_sense_valid(sshdr) &&
2171 sshdr->sense_key == UNIT_ATTENTION)
2172 sdev->changed = 1;
2173 } while (scsi_sense_valid(sshdr) &&
2174 sshdr->sense_key == UNIT_ATTENTION && --retries);
2175
2176 return result;
2177}
2178EXPORT_SYMBOL(scsi_test_unit_ready);
2179
2180/**
2181 * scsi_device_set_state - Take the given device through the device state model.
2182 * @sdev: scsi device to change the state of.
2183 * @state: state to change to.
2184 *
2185 * Returns zero if successful or an error if the requested
2186 * transition is illegal.
2187 */
2188int
2189scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2190{
2191 enum scsi_device_state oldstate = sdev->sdev_state;
2192
2193 if (state == oldstate)
2194 return 0;
2195
2196 switch (state) {
2197 case SDEV_CREATED:
2198 switch (oldstate) {
2199 case SDEV_CREATED_BLOCK:
2200 break;
2201 default:
2202 goto illegal;
2203 }
2204 break;
2205
2206 case SDEV_RUNNING:
2207 switch (oldstate) {
2208 case SDEV_CREATED:
2209 case SDEV_OFFLINE:
2210 case SDEV_TRANSPORT_OFFLINE:
2211 case SDEV_QUIESCE:
2212 case SDEV_BLOCK:
2213 break;
2214 default:
2215 goto illegal;
2216 }
2217 break;
2218
2219 case SDEV_QUIESCE:
2220 switch (oldstate) {
2221 case SDEV_RUNNING:
2222 case SDEV_OFFLINE:
2223 case SDEV_TRANSPORT_OFFLINE:
2224 break;
2225 default:
2226 goto illegal;
2227 }
2228 break;
2229
2230 case SDEV_OFFLINE:
2231 case SDEV_TRANSPORT_OFFLINE:
2232 switch (oldstate) {
2233 case SDEV_CREATED:
2234 case SDEV_RUNNING:
2235 case SDEV_QUIESCE:
2236 case SDEV_BLOCK:
2237 break;
2238 default:
2239 goto illegal;
2240 }
2241 break;
2242
2243 case SDEV_BLOCK:
2244 switch (oldstate) {
2245 case SDEV_RUNNING:
2246 case SDEV_CREATED_BLOCK:
2247 case SDEV_OFFLINE:
2248 break;
2249 default:
2250 goto illegal;
2251 }
2252 break;
2253
2254 case SDEV_CREATED_BLOCK:
2255 switch (oldstate) {
2256 case SDEV_CREATED:
2257 break;
2258 default:
2259 goto illegal;
2260 }
2261 break;
2262
2263 case SDEV_CANCEL:
2264 switch (oldstate) {
2265 case SDEV_CREATED:
2266 case SDEV_RUNNING:
2267 case SDEV_QUIESCE:
2268 case SDEV_OFFLINE:
2269 case SDEV_TRANSPORT_OFFLINE:
2270 break;
2271 default:
2272 goto illegal;
2273 }
2274 break;
2275
2276 case SDEV_DEL:
2277 switch (oldstate) {
2278 case SDEV_CREATED:
2279 case SDEV_RUNNING:
2280 case SDEV_OFFLINE:
2281 case SDEV_TRANSPORT_OFFLINE:
2282 case SDEV_CANCEL:
2283 case SDEV_BLOCK:
2284 case SDEV_CREATED_BLOCK:
2285 break;
2286 default:
2287 goto illegal;
2288 }
2289 break;
2290
2291 }
2292 sdev->sdev_state = state;
2293 return 0;
2294
2295 illegal:
2296 SCSI_LOG_ERROR_RECOVERY(1,
2297 sdev_printk(KERN_ERR, sdev,
2298 "Illegal state transition %s->%s",
2299 scsi_device_state_name(oldstate),
2300 scsi_device_state_name(state))
2301 );
2302 return -EINVAL;
2303}
2304EXPORT_SYMBOL(scsi_device_set_state);
2305
2306/**
2307 * sdev_evt_emit - emit a single SCSI device uevent
2308 * @sdev: associated SCSI device
2309 * @evt: event to emit
2310 *
2311 * Send a single uevent (scsi_event) to the associated scsi_device.
2312 */
2313static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2314{
2315 int idx = 0;
2316 char *envp[3];
2317
2318 switch (evt->evt_type) {
2319 case SDEV_EVT_MEDIA_CHANGE:
2320 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2321 break;
2322 case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2323 scsi_rescan_device(&sdev->sdev_gendev);
2324 envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
2325 break;
2326 case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2327 envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
2328 break;
2329 case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2330 envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
2331 break;
2332 case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2333 envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
2334 break;
2335 case SDEV_EVT_LUN_CHANGE_REPORTED:
2336 envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
2337 break;
2338 case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2339 envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
2340 break;
2341 case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2342 envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED";
2343 break;
2344 default:
2345 /* do nothing */
2346 break;
2347 }
2348
2349 envp[idx++] = NULL;
2350
2351 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2352}
2353
2354/**
2355 * sdev_evt_thread - send a uevent for each scsi event
2356 * @work: work struct for scsi_device
2357 *
2358 * Dispatch queued events to their associated scsi_device kobjects
2359 * as uevents.
2360 */
2361void scsi_evt_thread(struct work_struct *work)
2362{
2363 struct scsi_device *sdev;
2364 enum scsi_device_event evt_type;
2365 LIST_HEAD(event_list);
2366
2367 sdev = container_of(work, struct scsi_device, event_work);
2368
2369 for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
2370 if (test_and_clear_bit(evt_type, sdev->pending_events))
2371 sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
2372
2373 while (1) {
2374 struct scsi_event *evt;
2375 struct list_head *this, *tmp;
2376 unsigned long flags;
2377
2378 spin_lock_irqsave(&sdev->list_lock, flags);
2379 list_splice_init(&sdev->event_list, &event_list);
2380 spin_unlock_irqrestore(&sdev->list_lock, flags);
2381
2382 if (list_empty(&event_list))
2383 break;
2384
2385 list_for_each_safe(this, tmp, &event_list) {
2386 evt = list_entry(this, struct scsi_event, node);
2387 list_del(&evt->node);
2388 scsi_evt_emit(sdev, evt);
2389 kfree(evt);
2390 }
2391 }
2392}
2393
2394/**
2395 * sdev_evt_send - send asserted event to uevent thread
2396 * @sdev: scsi_device event occurred on
2397 * @evt: event to send
2398 *
2399 * Assert scsi device event asynchronously.
2400 */
2401void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2402{
2403 unsigned long flags;
2404
2405#if 0
2406 /* FIXME: currently this check eliminates all media change events
2407 * for polled devices. Need to update to discriminate between AN
2408 * and polled events */
2409 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2410 kfree(evt);
2411 return;
2412 }
2413#endif
2414
2415 spin_lock_irqsave(&sdev->list_lock, flags);
2416 list_add_tail(&evt->node, &sdev->event_list);
2417 schedule_work(&sdev->event_work);
2418 spin_unlock_irqrestore(&sdev->list_lock, flags);
2419}
2420EXPORT_SYMBOL_GPL(sdev_evt_send);
2421
2422/**
2423 * sdev_evt_alloc - allocate a new scsi event
2424 * @evt_type: type of event to allocate
2425 * @gfpflags: GFP flags for allocation
2426 *
2427 * Allocates and returns a new scsi_event.
2428 */
2429struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2430 gfp_t gfpflags)
2431{
2432 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2433 if (!evt)
2434 return NULL;
2435
2436 evt->evt_type = evt_type;
2437 INIT_LIST_HEAD(&evt->node);
2438
2439 /* evt_type-specific initialization, if any */
2440 switch (evt_type) {
2441 case SDEV_EVT_MEDIA_CHANGE:
2442 case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2443 case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2444 case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2445 case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2446 case SDEV_EVT_LUN_CHANGE_REPORTED:
2447 case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2448 case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2449 default:
2450 /* do nothing */
2451 break;
2452 }
2453
2454 return evt;
2455}
2456EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2457
2458/**
2459 * sdev_evt_send_simple - send asserted event to uevent thread
2460 * @sdev: scsi_device event occurred on
2461 * @evt_type: type of event to send
2462 * @gfpflags: GFP flags for allocation
2463 *
2464 * Assert scsi device event asynchronously, given an event type.
2465 */
2466void sdev_evt_send_simple(struct scsi_device *sdev,
2467 enum scsi_device_event evt_type, gfp_t gfpflags)
2468{
2469 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2470 if (!evt) {
2471 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2472 evt_type);
2473 return;
2474 }
2475
2476 sdev_evt_send(sdev, evt);
2477}
2478EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2479
2480/**
2481 * scsi_device_quiesce - Block user issued commands.
2482 * @sdev: scsi device to quiesce.
2483 *
2484 * This works by trying to transition to the SDEV_QUIESCE state
2485 * (which must be a legal transition). When the device is in this
2486 * state, only special requests will be accepted, all others will
2487 * be deferred. Since special requests may also be requeued requests,
2488 * a successful return doesn't guarantee the device will be
2489 * totally quiescent.
2490 *
2491 * Must be called with user context, may sleep.
2492 *
2493 * Returns zero if unsuccessful or an error if not.
2494 */
2495int
2496scsi_device_quiesce(struct scsi_device *sdev)
2497{
2498 struct request_queue *q = sdev->request_queue;
2499 int err;
2500
2501 /*
2502 * It is allowed to call scsi_device_quiesce() multiple times from
2503 * the same context but concurrent scsi_device_quiesce() calls are
2504 * not allowed.
2505 */
2506 WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current);
2507
2508 if (sdev->quiesced_by == current)
2509 return 0;
2510
2511 blk_set_pm_only(q);
2512
2513 blk_mq_freeze_queue(q);
2514 /*
2515 * Ensure that the effect of blk_set_pm_only() will be visible
2516 * for percpu_ref_tryget() callers that occur after the queue
2517 * unfreeze even if the queue was already frozen before this function
2518 * was called. See also https://lwn.net/Articles/573497/.
2519 */
2520 synchronize_rcu();
2521 blk_mq_unfreeze_queue(q);
2522
2523 mutex_lock(&sdev->state_mutex);
2524 err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2525 if (err == 0)
2526 sdev->quiesced_by = current;
2527 else
2528 blk_clear_pm_only(q);
2529 mutex_unlock(&sdev->state_mutex);
2530
2531 return err;
2532}
2533EXPORT_SYMBOL(scsi_device_quiesce);
2534
2535/**
2536 * scsi_device_resume - Restart user issued commands to a quiesced device.
2537 * @sdev: scsi device to resume.
2538 *
2539 * Moves the device from quiesced back to running and restarts the
2540 * queues.
2541 *
2542 * Must be called with user context, may sleep.
2543 */
2544void scsi_device_resume(struct scsi_device *sdev)
2545{
2546 /* check if the device state was mutated prior to resume, and if
2547 * so assume the state is being managed elsewhere (for example
2548 * device deleted during suspend)
2549 */
2550 mutex_lock(&sdev->state_mutex);
2551 if (sdev->quiesced_by) {
2552 sdev->quiesced_by = NULL;
2553 blk_clear_pm_only(sdev->request_queue);
2554 }
2555 if (sdev->sdev_state == SDEV_QUIESCE)
2556 scsi_device_set_state(sdev, SDEV_RUNNING);
2557 mutex_unlock(&sdev->state_mutex);
2558}
2559EXPORT_SYMBOL(scsi_device_resume);
2560
2561static void
2562device_quiesce_fn(struct scsi_device *sdev, void *data)
2563{
2564 scsi_device_quiesce(sdev);
2565}
2566
2567void
2568scsi_target_quiesce(struct scsi_target *starget)
2569{
2570 starget_for_each_device(starget, NULL, device_quiesce_fn);
2571}
2572EXPORT_SYMBOL(scsi_target_quiesce);
2573
2574static void
2575device_resume_fn(struct scsi_device *sdev, void *data)
2576{
2577 scsi_device_resume(sdev);
2578}
2579
2580void
2581scsi_target_resume(struct scsi_target *starget)
2582{
2583 starget_for_each_device(starget, NULL, device_resume_fn);
2584}
2585EXPORT_SYMBOL(scsi_target_resume);
2586
2587/**
2588 * scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state
2589 * @sdev: device to block
2590 *
2591 * Pause SCSI command processing on the specified device. Does not sleep.
2592 *
2593 * Returns zero if successful or a negative error code upon failure.
2594 *
2595 * Notes:
2596 * This routine transitions the device to the SDEV_BLOCK state (which must be
2597 * a legal transition). When the device is in this state, command processing
2598 * is paused until the device leaves the SDEV_BLOCK state. See also
2599 * scsi_internal_device_unblock_nowait().
2600 */
2601int scsi_internal_device_block_nowait(struct scsi_device *sdev)
2602{
2603 struct request_queue *q = sdev->request_queue;
2604 int err = 0;
2605
2606 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2607 if (err) {
2608 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2609
2610 if (err)
2611 return err;
2612 }
2613
2614 /*
2615 * The device has transitioned to SDEV_BLOCK. Stop the
2616 * block layer from calling the midlayer with this device's
2617 * request queue.
2618 */
2619 blk_mq_quiesce_queue_nowait(q);
2620 return 0;
2621}
2622EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
2623
2624/**
2625 * scsi_internal_device_block - try to transition to the SDEV_BLOCK state
2626 * @sdev: device to block
2627 *
2628 * Pause SCSI command processing on the specified device and wait until all
2629 * ongoing scsi_request_fn() / scsi_queue_rq() calls have finished. May sleep.
2630 *
2631 * Returns zero if successful or a negative error code upon failure.
2632 *
2633 * Note:
2634 * This routine transitions the device to the SDEV_BLOCK state (which must be
2635 * a legal transition). When the device is in this state, command processing
2636 * is paused until the device leaves the SDEV_BLOCK state. See also
2637 * scsi_internal_device_unblock().
2638 *
2639 * To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
2640 * scsi_internal_device_block() has blocked a SCSI device and also
2641 * remove the rport mutex lock and unlock calls from srp_queuecommand().
2642 */
2643static int scsi_internal_device_block(struct scsi_device *sdev)
2644{
2645 struct request_queue *q = sdev->request_queue;
2646 int err;
2647
2648 mutex_lock(&sdev->state_mutex);
2649 err = scsi_internal_device_block_nowait(sdev);
2650 if (err == 0)
2651 blk_mq_quiesce_queue(q);
2652 mutex_unlock(&sdev->state_mutex);
2653
2654 return err;
2655}
2656
2657void scsi_start_queue(struct scsi_device *sdev)
2658{
2659 struct request_queue *q = sdev->request_queue;
2660
2661 blk_mq_unquiesce_queue(q);
2662}
2663
2664/**
2665 * scsi_internal_device_unblock_nowait - resume a device after a block request
2666 * @sdev: device to resume
2667 * @new_state: state to set the device to after unblocking
2668 *
2669 * Restart the device queue for a previously suspended SCSI device. Does not
2670 * sleep.
2671 *
2672 * Returns zero if successful or a negative error code upon failure.
2673 *
2674 * Notes:
2675 * This routine transitions the device to the SDEV_RUNNING state or to one of
2676 * the offline states (which must be a legal transition) allowing the midlayer
2677 * to goose the queue for this device.
2678 */
2679int scsi_internal_device_unblock_nowait(struct scsi_device *sdev,
2680 enum scsi_device_state new_state)
2681{
2682 /*
2683 * Try to transition the scsi device to SDEV_RUNNING or one of the
2684 * offlined states and goose the device queue if successful.
2685 */
2686 switch (sdev->sdev_state) {
2687 case SDEV_BLOCK:
2688 case SDEV_TRANSPORT_OFFLINE:
2689 sdev->sdev_state = new_state;
2690 break;
2691 case SDEV_CREATED_BLOCK:
2692 if (new_state == SDEV_TRANSPORT_OFFLINE ||
2693 new_state == SDEV_OFFLINE)
2694 sdev->sdev_state = new_state;
2695 else
2696 sdev->sdev_state = SDEV_CREATED;
2697 break;
2698 case SDEV_CANCEL:
2699 case SDEV_OFFLINE:
2700 break;
2701 default:
2702 return -EINVAL;
2703 }
2704 scsi_start_queue(sdev);
2705
2706 return 0;
2707}
2708EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
2709
2710/**
2711 * scsi_internal_device_unblock - resume a device after a block request
2712 * @sdev: device to resume
2713 * @new_state: state to set the device to after unblocking
2714 *
2715 * Restart the device queue for a previously suspended SCSI device. May sleep.
2716 *
2717 * Returns zero if successful or a negative error code upon failure.
2718 *
2719 * Notes:
2720 * This routine transitions the device to the SDEV_RUNNING state or to one of
2721 * the offline states (which must be a legal transition) allowing the midlayer
2722 * to goose the queue for this device.
2723 */
2724static int scsi_internal_device_unblock(struct scsi_device *sdev,
2725 enum scsi_device_state new_state)
2726{
2727 int ret;
2728
2729 mutex_lock(&sdev->state_mutex);
2730 ret = scsi_internal_device_unblock_nowait(sdev, new_state);
2731 mutex_unlock(&sdev->state_mutex);
2732
2733 return ret;
2734}
2735
2736static void
2737device_block(struct scsi_device *sdev, void *data)
2738{
2739 scsi_internal_device_block(sdev);
2740}
2741
2742static int
2743target_block(struct device *dev, void *data)
2744{
2745 if (scsi_is_target_device(dev))
2746 starget_for_each_device(to_scsi_target(dev), NULL,
2747 device_block);
2748 return 0;
2749}
2750
2751void
2752scsi_target_block(struct device *dev)
2753{
2754 if (scsi_is_target_device(dev))
2755 starget_for_each_device(to_scsi_target(dev), NULL,
2756 device_block);
2757 else
2758 device_for_each_child(dev, NULL, target_block);
2759}
2760EXPORT_SYMBOL_GPL(scsi_target_block);
2761
2762static void
2763device_unblock(struct scsi_device *sdev, void *data)
2764{
2765 scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
2766}
2767
2768static int
2769target_unblock(struct device *dev, void *data)
2770{
2771 if (scsi_is_target_device(dev))
2772 starget_for_each_device(to_scsi_target(dev), data,
2773 device_unblock);
2774 return 0;
2775}
2776
2777void
2778scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
2779{
2780 if (scsi_is_target_device(dev))
2781 starget_for_each_device(to_scsi_target(dev), &new_state,
2782 device_unblock);
2783 else
2784 device_for_each_child(dev, &new_state, target_unblock);
2785}
2786EXPORT_SYMBOL_GPL(scsi_target_unblock);
2787
2788/**
2789 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2790 * @sgl: scatter-gather list
2791 * @sg_count: number of segments in sg
2792 * @offset: offset in bytes into sg, on return offset into the mapped area
2793 * @len: bytes to map, on return number of bytes mapped
2794 *
2795 * Returns virtual address of the start of the mapped page
2796 */
2797void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2798 size_t *offset, size_t *len)
2799{
2800 int i;
2801 size_t sg_len = 0, len_complete = 0;
2802 struct scatterlist *sg;
2803 struct page *page;
2804
2805 WARN_ON(!irqs_disabled());
2806
2807 for_each_sg(sgl, sg, sg_count, i) {
2808 len_complete = sg_len; /* Complete sg-entries */
2809 sg_len += sg->length;
2810 if (sg_len > *offset)
2811 break;
2812 }
2813
2814 if (unlikely(i == sg_count)) {
2815 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2816 "elements %d\n",
2817 __func__, sg_len, *offset, sg_count);
2818 WARN_ON(1);
2819 return NULL;
2820 }
2821
2822 /* Offset starting from the beginning of first page in this sg-entry */
2823 *offset = *offset - len_complete + sg->offset;
2824
2825 /* Assumption: contiguous pages can be accessed as "page + i" */
2826 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2827 *offset &= ~PAGE_MASK;
2828
2829 /* Bytes in this sg-entry from *offset to the end of the page */
2830 sg_len = PAGE_SIZE - *offset;
2831 if (*len > sg_len)
2832 *len = sg_len;
2833
2834 return kmap_atomic(page);
2835}
2836EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2837
2838/**
2839 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2840 * @virt: virtual address to be unmapped
2841 */
2842void scsi_kunmap_atomic_sg(void *virt)
2843{
2844 kunmap_atomic(virt);
2845}
2846EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
2847
2848void sdev_disable_disk_events(struct scsi_device *sdev)
2849{
2850 atomic_inc(&sdev->disk_events_disable_depth);
2851}
2852EXPORT_SYMBOL(sdev_disable_disk_events);
2853
2854void sdev_enable_disk_events(struct scsi_device *sdev)
2855{
2856 if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
2857 return;
2858 atomic_dec(&sdev->disk_events_disable_depth);
2859}
2860EXPORT_SYMBOL(sdev_enable_disk_events);
2861
2862/**
2863 * scsi_vpd_lun_id - return a unique device identification
2864 * @sdev: SCSI device
2865 * @id: buffer for the identification
2866 * @id_len: length of the buffer
2867 *
2868 * Copies a unique device identification into @id based
2869 * on the information in the VPD page 0x83 of the device.
2870 * The string will be formatted as a SCSI name string.
2871 *
2872 * Returns the length of the identification or error on failure.
2873 * If the identifier is longer than the supplied buffer the actual
2874 * identifier length is returned and the buffer is not zero-padded.
2875 */
2876int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
2877{
2878 u8 cur_id_type = 0xff;
2879 u8 cur_id_size = 0;
2880 const unsigned char *d, *cur_id_str;
2881 const struct scsi_vpd *vpd_pg83;
2882 int id_size = -EINVAL;
2883
2884 rcu_read_lock();
2885 vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
2886 if (!vpd_pg83) {
2887 rcu_read_unlock();
2888 return -ENXIO;
2889 }
2890
2891 /*
2892 * Look for the correct descriptor.
2893 * Order of preference for lun descriptor:
2894 * - SCSI name string
2895 * - NAA IEEE Registered Extended
2896 * - EUI-64 based 16-byte
2897 * - EUI-64 based 12-byte
2898 * - NAA IEEE Registered
2899 * - NAA IEEE Extended
2900 * - T10 Vendor ID
2901 * as longer descriptors reduce the likelyhood
2902 * of identification clashes.
2903 */
2904
2905 /* The id string must be at least 20 bytes + terminating NULL byte */
2906 if (id_len < 21) {
2907 rcu_read_unlock();
2908 return -EINVAL;
2909 }
2910
2911 memset(id, 0, id_len);
2912 d = vpd_pg83->data + 4;
2913 while (d < vpd_pg83->data + vpd_pg83->len) {
2914 /* Skip designators not referring to the LUN */
2915 if ((d[1] & 0x30) != 0x00)
2916 goto next_desig;
2917
2918 switch (d[1] & 0xf) {
2919 case 0x1:
2920 /* T10 Vendor ID */
2921 if (cur_id_size > d[3])
2922 break;
2923 /* Prefer anything */
2924 if (cur_id_type > 0x01 && cur_id_type != 0xff)
2925 break;
2926 cur_id_size = d[3];
2927 if (cur_id_size + 4 > id_len)
2928 cur_id_size = id_len - 4;
2929 cur_id_str = d + 4;
2930 cur_id_type = d[1] & 0xf;
2931 id_size = snprintf(id, id_len, "t10.%*pE",
2932 cur_id_size, cur_id_str);
2933 break;
2934 case 0x2:
2935 /* EUI-64 */
2936 if (cur_id_size > d[3])
2937 break;
2938 /* Prefer NAA IEEE Registered Extended */
2939 if (cur_id_type == 0x3 &&
2940 cur_id_size == d[3])
2941 break;
2942 cur_id_size = d[3];
2943 cur_id_str = d + 4;
2944 cur_id_type = d[1] & 0xf;
2945 switch (cur_id_size) {
2946 case 8:
2947 id_size = snprintf(id, id_len,
2948 "eui.%8phN",
2949 cur_id_str);
2950 break;
2951 case 12:
2952 id_size = snprintf(id, id_len,
2953 "eui.%12phN",
2954 cur_id_str);
2955 break;
2956 case 16:
2957 id_size = snprintf(id, id_len,
2958 "eui.%16phN",
2959 cur_id_str);
2960 break;
2961 default:
2962 cur_id_size = 0;
2963 break;
2964 }
2965 break;
2966 case 0x3:
2967 /* NAA */
2968 if (cur_id_size > d[3])
2969 break;
2970 cur_id_size = d[3];
2971 cur_id_str = d + 4;
2972 cur_id_type = d[1] & 0xf;
2973 switch (cur_id_size) {
2974 case 8:
2975 id_size = snprintf(id, id_len,
2976 "naa.%8phN",
2977 cur_id_str);
2978 break;
2979 case 16:
2980 id_size = snprintf(id, id_len,
2981 "naa.%16phN",
2982 cur_id_str);
2983 break;
2984 default:
2985 cur_id_size = 0;
2986 break;
2987 }
2988 break;
2989 case 0x8:
2990 /* SCSI name string */
2991 if (cur_id_size + 4 > d[3])
2992 break;
2993 /* Prefer others for truncated descriptor */
2994 if (cur_id_size && d[3] > id_len)
2995 break;
2996 cur_id_size = id_size = d[3];
2997 cur_id_str = d + 4;
2998 cur_id_type = d[1] & 0xf;
2999 if (cur_id_size >= id_len)
3000 cur_id_size = id_len - 1;
3001 memcpy(id, cur_id_str, cur_id_size);
3002 /* Decrease priority for truncated descriptor */
3003 if (cur_id_size != id_size)
3004 cur_id_size = 6;
3005 break;
3006 default:
3007 break;
3008 }
3009next_desig:
3010 d += d[3] + 4;
3011 }
3012 rcu_read_unlock();
3013
3014 return id_size;
3015}
3016EXPORT_SYMBOL(scsi_vpd_lun_id);
3017
3018/*
3019 * scsi_vpd_tpg_id - return a target port group identifier
3020 * @sdev: SCSI device
3021 *
3022 * Returns the Target Port Group identifier from the information
3023 * froom VPD page 0x83 of the device.
3024 *
3025 * Returns the identifier or error on failure.
3026 */
3027int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
3028{
3029 const unsigned char *d;
3030 const struct scsi_vpd *vpd_pg83;
3031 int group_id = -EAGAIN, rel_port = -1;
3032
3033 rcu_read_lock();
3034 vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3035 if (!vpd_pg83) {
3036 rcu_read_unlock();
3037 return -ENXIO;
3038 }
3039
3040 d = vpd_pg83->data + 4;
3041 while (d < vpd_pg83->data + vpd_pg83->len) {
3042 switch (d[1] & 0xf) {
3043 case 0x4:
3044 /* Relative target port */
3045 rel_port = get_unaligned_be16(&d[6]);
3046 break;
3047 case 0x5:
3048 /* Target port group */
3049 group_id = get_unaligned_be16(&d[6]);
3050 break;
3051 default:
3052 break;
3053 }
3054 d += d[3] + 4;
3055 }
3056 rcu_read_unlock();
3057
3058 if (group_id >= 0 && rel_id && rel_port != -1)
3059 *rel_id = rel_port;
3060
3061 return group_id;
3062}
3063EXPORT_SYMBOL(scsi_vpd_tpg_id);
3064