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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/scsi/scsi_lib.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c2023
1 files changed, 2023 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
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index 000000000000..7cbc4127fb5a
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+++ b/drivers/scsi/scsi_lib.c
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1/*
2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
3 *
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
8 */
9
10#include <linux/bio.h>
11#include <linux/blkdev.h>
12#include <linux/completion.h>
13#include <linux/kernel.h>
14#include <linux/mempool.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/pci.h>
18#include <linux/delay.h>
19
20#include <scsi/scsi.h>
21#include <scsi/scsi_dbg.h>
22#include <scsi/scsi_device.h>
23#include <scsi/scsi_driver.h>
24#include <scsi/scsi_eh.h>
25#include <scsi/scsi_host.h>
26#include <scsi/scsi_request.h>
27
28#include "scsi_priv.h"
29#include "scsi_logging.h"
30
31
32#define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
33#define SG_MEMPOOL_SIZE 32
34
35struct scsi_host_sg_pool {
36 size_t size;
37 char *name;
38 kmem_cache_t *slab;
39 mempool_t *pool;
40};
41
42#if (SCSI_MAX_PHYS_SEGMENTS < 32)
43#error SCSI_MAX_PHYS_SEGMENTS is too small
44#endif
45
46#define SP(x) { x, "sgpool-" #x }
47struct scsi_host_sg_pool scsi_sg_pools[] = {
48 SP(8),
49 SP(16),
50 SP(32),
51#if (SCSI_MAX_PHYS_SEGMENTS > 32)
52 SP(64),
53#if (SCSI_MAX_PHYS_SEGMENTS > 64)
54 SP(128),
55#if (SCSI_MAX_PHYS_SEGMENTS > 128)
56 SP(256),
57#if (SCSI_MAX_PHYS_SEGMENTS > 256)
58#error SCSI_MAX_PHYS_SEGMENTS is too large
59#endif
60#endif
61#endif
62#endif
63};
64#undef SP
65
66
67/*
68 * Function: scsi_insert_special_req()
69 *
70 * Purpose: Insert pre-formed request into request queue.
71 *
72 * Arguments: sreq - request that is ready to be queued.
73 * at_head - boolean. True if we should insert at head
74 * of queue, false if we should insert at tail.
75 *
76 * Lock status: Assumed that lock is not held upon entry.
77 *
78 * Returns: Nothing
79 *
80 * Notes: This function is called from character device and from
81 * ioctl types of functions where the caller knows exactly
82 * what SCSI command needs to be issued. The idea is that
83 * we merely inject the command into the queue (at the head
84 * for now), and then call the queue request function to actually
85 * process it.
86 */
87int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
88{
89 /*
90 * Because users of this function are apt to reuse requests with no
91 * modification, we have to sanitise the request flags here
92 */
93 sreq->sr_request->flags &= ~REQ_DONTPREP;
94 blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
95 at_head, sreq, 0);
96 return 0;
97}
98
99/*
100 * Function: scsi_queue_insert()
101 *
102 * Purpose: Insert a command in the midlevel queue.
103 *
104 * Arguments: cmd - command that we are adding to queue.
105 * reason - why we are inserting command to queue.
106 *
107 * Lock status: Assumed that lock is not held upon entry.
108 *
109 * Returns: Nothing.
110 *
111 * Notes: We do this for one of two cases. Either the host is busy
112 * and it cannot accept any more commands for the time being,
113 * or the device returned QUEUE_FULL and can accept no more
114 * commands.
115 * Notes: This could be called either from an interrupt context or a
116 * normal process context.
117 */
118int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
119{
120 struct Scsi_Host *host = cmd->device->host;
121 struct scsi_device *device = cmd->device;
122
123 SCSI_LOG_MLQUEUE(1,
124 printk("Inserting command %p into mlqueue\n", cmd));
125
126 /*
127 * We are inserting the command into the ml queue. First, we
128 * cancel the timer, so it doesn't time out.
129 */
130 scsi_delete_timer(cmd);
131
132 /*
133 * Next, set the appropriate busy bit for the device/host.
134 *
135 * If the host/device isn't busy, assume that something actually
136 * completed, and that we should be able to queue a command now.
137 *
138 * Note that the prior mid-layer assumption that any host could
139 * always queue at least one command is now broken. The mid-layer
140 * will implement a user specifiable stall (see
141 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
142 * if a command is requeued with no other commands outstanding
143 * either for the device or for the host.
144 */
145 if (reason == SCSI_MLQUEUE_HOST_BUSY)
146 host->host_blocked = host->max_host_blocked;
147 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
148 device->device_blocked = device->max_device_blocked;
149
150 /*
151 * Register the fact that we own the thing for now.
152 */
153 cmd->state = SCSI_STATE_MLQUEUE;
154 cmd->owner = SCSI_OWNER_MIDLEVEL;
155
156 /*
157 * Decrement the counters, since these commands are no longer
158 * active on the host/device.
159 */
160 scsi_device_unbusy(device);
161
162 /*
163 * Insert this command at the head of the queue for it's device.
164 * It will go before all other commands that are already in the queue.
165 *
166 * NOTE: there is magic here about the way the queue is plugged if
167 * we have no outstanding commands.
168 *
169 * Although this *doesn't* plug the queue, it does call the request
170 * function. The SCSI request function detects the blocked condition
171 * and plugs the queue appropriately.
172 */
173 blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1);
174 return 0;
175}
176
177/*
178 * Function: scsi_do_req
179 *
180 * Purpose: Queue a SCSI request
181 *
182 * Arguments: sreq - command descriptor.
183 * cmnd - actual SCSI command to be performed.
184 * buffer - data buffer.
185 * bufflen - size of data buffer.
186 * done - completion function to be run.
187 * timeout - how long to let it run before timeout.
188 * retries - number of retries we allow.
189 *
190 * Lock status: No locks held upon entry.
191 *
192 * Returns: Nothing.
193 *
194 * Notes: This function is only used for queueing requests for things
195 * like ioctls and character device requests - this is because
196 * we essentially just inject a request into the queue for the
197 * device.
198 *
199 * In order to support the scsi_device_quiesce function, we
200 * now inject requests on the *head* of the device queue
201 * rather than the tail.
202 */
203void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
204 void *buffer, unsigned bufflen,
205 void (*done)(struct scsi_cmnd *),
206 int timeout, int retries)
207{
208 /*
209 * If the upper level driver is reusing these things, then
210 * we should release the low-level block now. Another one will
211 * be allocated later when this request is getting queued.
212 */
213 __scsi_release_request(sreq);
214
215 /*
216 * Our own function scsi_done (which marks the host as not busy,
217 * disables the timeout counter, etc) will be called by us or by the
218 * scsi_hosts[host].queuecommand() function needs to also call
219 * the completion function for the high level driver.
220 */
221 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
222 sreq->sr_bufflen = bufflen;
223 sreq->sr_buffer = buffer;
224 sreq->sr_allowed = retries;
225 sreq->sr_done = done;
226 sreq->sr_timeout_per_command = timeout;
227
228 if (sreq->sr_cmd_len == 0)
229 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
230
231 /*
232 * head injection *required* here otherwise quiesce won't work
233 */
234 scsi_insert_special_req(sreq, 1);
235}
236EXPORT_SYMBOL(scsi_do_req);
237
238static void scsi_wait_done(struct scsi_cmnd *cmd)
239{
240 struct request *req = cmd->request;
241 struct request_queue *q = cmd->device->request_queue;
242 unsigned long flags;
243
244 req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
245
246 spin_lock_irqsave(q->queue_lock, flags);
247 if (blk_rq_tagged(req))
248 blk_queue_end_tag(q, req);
249 spin_unlock_irqrestore(q->queue_lock, flags);
250
251 if (req->waiting)
252 complete(req->waiting);
253}
254
255/* This is the end routine we get to if a command was never attached
256 * to the request. Simply complete the request without changing
257 * rq_status; this will cause a DRIVER_ERROR. */
258static void scsi_wait_req_end_io(struct request *req)
259{
260 BUG_ON(!req->waiting);
261
262 complete(req->waiting);
263}
264
265void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
266 unsigned bufflen, int timeout, int retries)
267{
268 DECLARE_COMPLETION(wait);
269
270 sreq->sr_request->waiting = &wait;
271 sreq->sr_request->rq_status = RQ_SCSI_BUSY;
272 sreq->sr_request->end_io = scsi_wait_req_end_io;
273 scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
274 timeout, retries);
275 wait_for_completion(&wait);
276 sreq->sr_request->waiting = NULL;
277 if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
278 sreq->sr_result |= (DRIVER_ERROR << 24);
279
280 __scsi_release_request(sreq);
281}
282EXPORT_SYMBOL(scsi_wait_req);
283
284/*
285 * Function: scsi_init_cmd_errh()
286 *
287 * Purpose: Initialize cmd fields related to error handling.
288 *
289 * Arguments: cmd - command that is ready to be queued.
290 *
291 * Returns: Nothing
292 *
293 * Notes: This function has the job of initializing a number of
294 * fields related to error handling. Typically this will
295 * be called once for each command, as required.
296 */
297static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
298{
299 cmd->owner = SCSI_OWNER_MIDLEVEL;
300 cmd->serial_number = 0;
301 cmd->serial_number_at_timeout = 0;
302 cmd->abort_reason = 0;
303
304 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
305
306 if (cmd->cmd_len == 0)
307 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
308
309 /*
310 * We need saved copies of a number of fields - this is because
311 * error handling may need to overwrite these with different values
312 * to run different commands, and once error handling is complete,
313 * we will need to restore these values prior to running the actual
314 * command.
315 */
316 cmd->old_use_sg = cmd->use_sg;
317 cmd->old_cmd_len = cmd->cmd_len;
318 cmd->sc_old_data_direction = cmd->sc_data_direction;
319 cmd->old_underflow = cmd->underflow;
320 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
321 cmd->buffer = cmd->request_buffer;
322 cmd->bufflen = cmd->request_bufflen;
323 cmd->internal_timeout = NORMAL_TIMEOUT;
324 cmd->abort_reason = 0;
325
326 return 1;
327}
328
329/*
330 * Function: scsi_setup_cmd_retry()
331 *
332 * Purpose: Restore the command state for a retry
333 *
334 * Arguments: cmd - command to be restored
335 *
336 * Returns: Nothing
337 *
338 * Notes: Immediately prior to retrying a command, we need
339 * to restore certain fields that we saved above.
340 */
341void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
342{
343 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
344 cmd->request_buffer = cmd->buffer;
345 cmd->request_bufflen = cmd->bufflen;
346 cmd->use_sg = cmd->old_use_sg;
347 cmd->cmd_len = cmd->old_cmd_len;
348 cmd->sc_data_direction = cmd->sc_old_data_direction;
349 cmd->underflow = cmd->old_underflow;
350}
351
352void scsi_device_unbusy(struct scsi_device *sdev)
353{
354 struct Scsi_Host *shost = sdev->host;
355 unsigned long flags;
356
357 spin_lock_irqsave(shost->host_lock, flags);
358 shost->host_busy--;
359 if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
360 shost->host_failed))
361 scsi_eh_wakeup(shost);
362 spin_unlock(shost->host_lock);
363 spin_lock(&sdev->sdev_lock);
364 sdev->device_busy--;
365 spin_unlock_irqrestore(&sdev->sdev_lock, flags);
366}
367
368/*
369 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
370 * and call blk_run_queue for all the scsi_devices on the target -
371 * including current_sdev first.
372 *
373 * Called with *no* scsi locks held.
374 */
375static void scsi_single_lun_run(struct scsi_device *current_sdev)
376{
377 struct Scsi_Host *shost = current_sdev->host;
378 struct scsi_device *sdev, *tmp;
379 struct scsi_target *starget = scsi_target(current_sdev);
380 unsigned long flags;
381
382 spin_lock_irqsave(shost->host_lock, flags);
383 starget->starget_sdev_user = NULL;
384 spin_unlock_irqrestore(shost->host_lock, flags);
385
386 /*
387 * Call blk_run_queue for all LUNs on the target, starting with
388 * current_sdev. We race with others (to set starget_sdev_user),
389 * but in most cases, we will be first. Ideally, each LU on the
390 * target would get some limited time or requests on the target.
391 */
392 blk_run_queue(current_sdev->request_queue);
393
394 spin_lock_irqsave(shost->host_lock, flags);
395 if (starget->starget_sdev_user)
396 goto out;
397 list_for_each_entry_safe(sdev, tmp, &starget->devices,
398 same_target_siblings) {
399 if (sdev == current_sdev)
400 continue;
401 if (scsi_device_get(sdev))
402 continue;
403
404 spin_unlock_irqrestore(shost->host_lock, flags);
405 blk_run_queue(sdev->request_queue);
406 spin_lock_irqsave(shost->host_lock, flags);
407
408 scsi_device_put(sdev);
409 }
410 out:
411 spin_unlock_irqrestore(shost->host_lock, flags);
412}
413
414/*
415 * Function: scsi_run_queue()
416 *
417 * Purpose: Select a proper request queue to serve next
418 *
419 * Arguments: q - last request's queue
420 *
421 * Returns: Nothing
422 *
423 * Notes: The previous command was completely finished, start
424 * a new one if possible.
425 */
426static void scsi_run_queue(struct request_queue *q)
427{
428 struct scsi_device *sdev = q->queuedata;
429 struct Scsi_Host *shost = sdev->host;
430 unsigned long flags;
431
432 if (sdev->single_lun)
433 scsi_single_lun_run(sdev);
434
435 spin_lock_irqsave(shost->host_lock, flags);
436 while (!list_empty(&shost->starved_list) &&
437 !shost->host_blocked && !shost->host_self_blocked &&
438 !((shost->can_queue > 0) &&
439 (shost->host_busy >= shost->can_queue))) {
440 /*
441 * As long as shost is accepting commands and we have
442 * starved queues, call blk_run_queue. scsi_request_fn
443 * drops the queue_lock and can add us back to the
444 * starved_list.
445 *
446 * host_lock protects the starved_list and starved_entry.
447 * scsi_request_fn must get the host_lock before checking
448 * or modifying starved_list or starved_entry.
449 */
450 sdev = list_entry(shost->starved_list.next,
451 struct scsi_device, starved_entry);
452 list_del_init(&sdev->starved_entry);
453 spin_unlock_irqrestore(shost->host_lock, flags);
454
455 blk_run_queue(sdev->request_queue);
456
457 spin_lock_irqsave(shost->host_lock, flags);
458 if (unlikely(!list_empty(&sdev->starved_entry)))
459 /*
460 * sdev lost a race, and was put back on the
461 * starved list. This is unlikely but without this
462 * in theory we could loop forever.
463 */
464 break;
465 }
466 spin_unlock_irqrestore(shost->host_lock, flags);
467
468 blk_run_queue(q);
469}
470
471/*
472 * Function: scsi_requeue_command()
473 *
474 * Purpose: Handle post-processing of completed commands.
475 *
476 * Arguments: q - queue to operate on
477 * cmd - command that may need to be requeued.
478 *
479 * Returns: Nothing
480 *
481 * Notes: After command completion, there may be blocks left
482 * over which weren't finished by the previous command
483 * this can be for a number of reasons - the main one is
484 * I/O errors in the middle of the request, in which case
485 * we need to request the blocks that come after the bad
486 * sector.
487 */
488static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
489{
490 cmd->request->flags &= ~REQ_DONTPREP;
491 blk_insert_request(q, cmd->request, 1, cmd, 1);
492
493 scsi_run_queue(q);
494}
495
496void scsi_next_command(struct scsi_cmnd *cmd)
497{
498 struct request_queue *q = cmd->device->request_queue;
499
500 scsi_put_command(cmd);
501 scsi_run_queue(q);
502}
503
504void scsi_run_host_queues(struct Scsi_Host *shost)
505{
506 struct scsi_device *sdev;
507
508 shost_for_each_device(sdev, shost)
509 scsi_run_queue(sdev->request_queue);
510}
511
512/*
513 * Function: scsi_end_request()
514 *
515 * Purpose: Post-processing of completed commands (usually invoked at end
516 * of upper level post-processing and scsi_io_completion).
517 *
518 * Arguments: cmd - command that is complete.
519 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
520 * bytes - number of bytes of completed I/O
521 * requeue - indicates whether we should requeue leftovers.
522 *
523 * Lock status: Assumed that lock is not held upon entry.
524 *
525 * Returns: cmd if requeue done or required, NULL otherwise
526 *
527 * Notes: This is called for block device requests in order to
528 * mark some number of sectors as complete.
529 *
530 * We are guaranteeing that the request queue will be goosed
531 * at some point during this call.
532 */
533static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
534 int bytes, int requeue)
535{
536 request_queue_t *q = cmd->device->request_queue;
537 struct request *req = cmd->request;
538 unsigned long flags;
539
540 /*
541 * If there are blocks left over at the end, set up the command
542 * to queue the remainder of them.
543 */
544 if (end_that_request_chunk(req, uptodate, bytes)) {
545 int leftover = (req->hard_nr_sectors << 9);
546
547 if (blk_pc_request(req))
548 leftover = req->data_len;
549
550 /* kill remainder if no retrys */
551 if (!uptodate && blk_noretry_request(req))
552 end_that_request_chunk(req, 0, leftover);
553 else {
554 if (requeue)
555 /*
556 * Bleah. Leftovers again. Stick the
557 * leftovers in the front of the
558 * queue, and goose the queue again.
559 */
560 scsi_requeue_command(q, cmd);
561
562 return cmd;
563 }
564 }
565
566 add_disk_randomness(req->rq_disk);
567
568 spin_lock_irqsave(q->queue_lock, flags);
569 if (blk_rq_tagged(req))
570 blk_queue_end_tag(q, req);
571 end_that_request_last(req);
572 spin_unlock_irqrestore(q->queue_lock, flags);
573
574 /*
575 * This will goose the queue request function at the end, so we don't
576 * need to worry about launching another command.
577 */
578 scsi_next_command(cmd);
579 return NULL;
580}
581
582static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
583{
584 struct scsi_host_sg_pool *sgp;
585 struct scatterlist *sgl;
586
587 BUG_ON(!cmd->use_sg);
588
589 switch (cmd->use_sg) {
590 case 1 ... 8:
591 cmd->sglist_len = 0;
592 break;
593 case 9 ... 16:
594 cmd->sglist_len = 1;
595 break;
596 case 17 ... 32:
597 cmd->sglist_len = 2;
598 break;
599#if (SCSI_MAX_PHYS_SEGMENTS > 32)
600 case 33 ... 64:
601 cmd->sglist_len = 3;
602 break;
603#if (SCSI_MAX_PHYS_SEGMENTS > 64)
604 case 65 ... 128:
605 cmd->sglist_len = 4;
606 break;
607#if (SCSI_MAX_PHYS_SEGMENTS > 128)
608 case 129 ... 256:
609 cmd->sglist_len = 5;
610 break;
611#endif
612#endif
613#endif
614 default:
615 return NULL;
616 }
617
618 sgp = scsi_sg_pools + cmd->sglist_len;
619 sgl = mempool_alloc(sgp->pool, gfp_mask);
620 if (sgl)
621 memset(sgl, 0, sgp->size);
622 return sgl;
623}
624
625static void scsi_free_sgtable(struct scatterlist *sgl, int index)
626{
627 struct scsi_host_sg_pool *sgp;
628
629 BUG_ON(index > SG_MEMPOOL_NR);
630
631 sgp = scsi_sg_pools + index;
632 mempool_free(sgl, sgp->pool);
633}
634
635/*
636 * Function: scsi_release_buffers()
637 *
638 * Purpose: Completion processing for block device I/O requests.
639 *
640 * Arguments: cmd - command that we are bailing.
641 *
642 * Lock status: Assumed that no lock is held upon entry.
643 *
644 * Returns: Nothing
645 *
646 * Notes: In the event that an upper level driver rejects a
647 * command, we must release resources allocated during
648 * the __init_io() function. Primarily this would involve
649 * the scatter-gather table, and potentially any bounce
650 * buffers.
651 */
652static void scsi_release_buffers(struct scsi_cmnd *cmd)
653{
654 struct request *req = cmd->request;
655
656 /*
657 * Free up any indirection buffers we allocated for DMA purposes.
658 */
659 if (cmd->use_sg)
660 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
661 else if (cmd->request_buffer != req->buffer)
662 kfree(cmd->request_buffer);
663
664 /*
665 * Zero these out. They now point to freed memory, and it is
666 * dangerous to hang onto the pointers.
667 */
668 cmd->buffer = NULL;
669 cmd->bufflen = 0;
670 cmd->request_buffer = NULL;
671 cmd->request_bufflen = 0;
672}
673
674/*
675 * Function: scsi_io_completion()
676 *
677 * Purpose: Completion processing for block device I/O requests.
678 *
679 * Arguments: cmd - command that is finished.
680 *
681 * Lock status: Assumed that no lock is held upon entry.
682 *
683 * Returns: Nothing
684 *
685 * Notes: This function is matched in terms of capabilities to
686 * the function that created the scatter-gather list.
687 * In other words, if there are no bounce buffers
688 * (the normal case for most drivers), we don't need
689 * the logic to deal with cleaning up afterwards.
690 *
691 * We must do one of several things here:
692 *
693 * a) Call scsi_end_request. This will finish off the
694 * specified number of sectors. If we are done, the
695 * command block will be released, and the queue
696 * function will be goosed. If we are not done, then
697 * scsi_end_request will directly goose the queue.
698 *
699 * b) We can just use scsi_requeue_command() here. This would
700 * be used if we just wanted to retry, for example.
701 */
702void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
703 unsigned int block_bytes)
704{
705 int result = cmd->result;
706 int this_count = cmd->bufflen;
707 request_queue_t *q = cmd->device->request_queue;
708 struct request *req = cmd->request;
709 int clear_errors = 1;
710 struct scsi_sense_hdr sshdr;
711 int sense_valid = 0;
712 int sense_deferred = 0;
713
714 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
715 return;
716
717 /*
718 * Free up any indirection buffers we allocated for DMA purposes.
719 * For the case of a READ, we need to copy the data out of the
720 * bounce buffer and into the real buffer.
721 */
722 if (cmd->use_sg)
723 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
724 else if (cmd->buffer != req->buffer) {
725 if (rq_data_dir(req) == READ) {
726 unsigned long flags;
727 char *to = bio_kmap_irq(req->bio, &flags);
728 memcpy(to, cmd->buffer, cmd->bufflen);
729 bio_kunmap_irq(to, &flags);
730 }
731 kfree(cmd->buffer);
732 }
733
734 if (result) {
735 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
736 if (sense_valid)
737 sense_deferred = scsi_sense_is_deferred(&sshdr);
738 }
739 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
740 req->errors = result;
741 if (result) {
742 clear_errors = 0;
743 if (sense_valid && req->sense) {
744 /*
745 * SG_IO wants current and deferred errors
746 */
747 int len = 8 + cmd->sense_buffer[7];
748
749 if (len > SCSI_SENSE_BUFFERSIZE)
750 len = SCSI_SENSE_BUFFERSIZE;
751 memcpy(req->sense, cmd->sense_buffer, len);
752 req->sense_len = len;
753 }
754 } else
755 req->data_len = cmd->resid;
756 }
757
758 /*
759 * Zero these out. They now point to freed memory, and it is
760 * dangerous to hang onto the pointers.
761 */
762 cmd->buffer = NULL;
763 cmd->bufflen = 0;
764 cmd->request_buffer = NULL;
765 cmd->request_bufflen = 0;
766
767 /*
768 * Next deal with any sectors which we were able to correctly
769 * handle.
770 */
771 if (good_bytes >= 0) {
772 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
773 req->nr_sectors, good_bytes));
774 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
775
776 if (clear_errors)
777 req->errors = 0;
778 /*
779 * If multiple sectors are requested in one buffer, then
780 * they will have been finished off by the first command.
781 * If not, then we have a multi-buffer command.
782 *
783 * If block_bytes != 0, it means we had a medium error
784 * of some sort, and that we want to mark some number of
785 * sectors as not uptodate. Thus we want to inhibit
786 * requeueing right here - we will requeue down below
787 * when we handle the bad sectors.
788 */
789 cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
790
791 /*
792 * If the command completed without error, then either finish off the
793 * rest of the command, or start a new one.
794 */
795 if (result == 0 || cmd == NULL ) {
796 return;
797 }
798 }
799 /*
800 * Now, if we were good little boys and girls, Santa left us a request
801 * sense buffer. We can extract information from this, so we
802 * can choose a block to remap, etc.
803 */
804 if (sense_valid && !sense_deferred) {
805 switch (sshdr.sense_key) {
806 case UNIT_ATTENTION:
807 if (cmd->device->removable) {
808 /* detected disc change. set a bit
809 * and quietly refuse further access.
810 */
811 cmd->device->changed = 1;
812 cmd = scsi_end_request(cmd, 0,
813 this_count, 1);
814 return;
815 } else {
816 /*
817 * Must have been a power glitch, or a
818 * bus reset. Could not have been a
819 * media change, so we just retry the
820 * request and see what happens.
821 */
822 scsi_requeue_command(q, cmd);
823 return;
824 }
825 break;
826 case ILLEGAL_REQUEST:
827 /*
828 * If we had an ILLEGAL REQUEST returned, then we may
829 * have performed an unsupported command. The only
830 * thing this should be would be a ten byte read where
831 * only a six byte read was supported. Also, on a
832 * system where READ CAPACITY failed, we may have read
833 * past the end of the disk.
834 */
835 if (cmd->device->use_10_for_rw &&
836 (cmd->cmnd[0] == READ_10 ||
837 cmd->cmnd[0] == WRITE_10)) {
838 cmd->device->use_10_for_rw = 0;
839 /*
840 * This will cause a retry with a 6-byte
841 * command.
842 */
843 scsi_requeue_command(q, cmd);
844 result = 0;
845 } else {
846 cmd = scsi_end_request(cmd, 0, this_count, 1);
847 return;
848 }
849 break;
850 case NOT_READY:
851 /*
852 * If the device is in the process of becoming ready,
853 * retry.
854 */
855 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
856 scsi_requeue_command(q, cmd);
857 return;
858 }
859 printk(KERN_INFO "Device %s not ready.\n",
860 req->rq_disk ? req->rq_disk->disk_name : "");
861 cmd = scsi_end_request(cmd, 0, this_count, 1);
862 return;
863 case VOLUME_OVERFLOW:
864 printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
865 cmd->device->host->host_no,
866 (int)cmd->device->channel,
867 (int)cmd->device->id, (int)cmd->device->lun);
868 __scsi_print_command(cmd->data_cmnd);
869 scsi_print_sense("", cmd);
870 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
871 return;
872 default:
873 break;
874 }
875 } /* driver byte != 0 */
876 if (host_byte(result) == DID_RESET) {
877 /*
878 * Third party bus reset or reset for error
879 * recovery reasons. Just retry the request
880 * and see what happens.
881 */
882 scsi_requeue_command(q, cmd);
883 return;
884 }
885 if (result) {
886 printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
887 "= 0x%x\n", cmd->device->host->host_no,
888 cmd->device->channel,
889 cmd->device->id,
890 cmd->device->lun, result);
891
892 if (driver_byte(result) & DRIVER_SENSE)
893 scsi_print_sense("", cmd);
894 /*
895 * Mark a single buffer as not uptodate. Queue the remainder.
896 * We sometimes get this cruft in the event that a medium error
897 * isn't properly reported.
898 */
899 block_bytes = req->hard_cur_sectors << 9;
900 if (!block_bytes)
901 block_bytes = req->data_len;
902 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
903 }
904}
905EXPORT_SYMBOL(scsi_io_completion);
906
907/*
908 * Function: scsi_init_io()
909 *
910 * Purpose: SCSI I/O initialize function.
911 *
912 * Arguments: cmd - Command descriptor we wish to initialize
913 *
914 * Returns: 0 on success
915 * BLKPREP_DEFER if the failure is retryable
916 * BLKPREP_KILL if the failure is fatal
917 */
918static int scsi_init_io(struct scsi_cmnd *cmd)
919{
920 struct request *req = cmd->request;
921 struct scatterlist *sgpnt;
922 int count;
923
924 /*
925 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
926 */
927 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
928 cmd->request_bufflen = req->data_len;
929 cmd->request_buffer = req->data;
930 req->buffer = req->data;
931 cmd->use_sg = 0;
932 return 0;
933 }
934
935 /*
936 * we used to not use scatter-gather for single segment request,
937 * but now we do (it makes highmem I/O easier to support without
938 * kmapping pages)
939 */
940 cmd->use_sg = req->nr_phys_segments;
941
942 /*
943 * if sg table allocation fails, requeue request later.
944 */
945 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
946 if (unlikely(!sgpnt)) {
947 req->flags |= REQ_SPECIAL;
948 return BLKPREP_DEFER;
949 }
950
951 cmd->request_buffer = (char *) sgpnt;
952 cmd->request_bufflen = req->nr_sectors << 9;
953 if (blk_pc_request(req))
954 cmd->request_bufflen = req->data_len;
955 req->buffer = NULL;
956
957 /*
958 * Next, walk the list, and fill in the addresses and sizes of
959 * each segment.
960 */
961 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
962
963 /*
964 * mapped well, send it off
965 */
966 if (likely(count <= cmd->use_sg)) {
967 cmd->use_sg = count;
968 return 0;
969 }
970
971 printk(KERN_ERR "Incorrect number of segments after building list\n");
972 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
973 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
974 req->current_nr_sectors);
975
976 /* release the command and kill it */
977 scsi_release_buffers(cmd);
978 scsi_put_command(cmd);
979 return BLKPREP_KILL;
980}
981
982static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
983{
984 struct scsi_device *sdev = q->queuedata;
985 struct scsi_driver *drv;
986
987 if (sdev->sdev_state == SDEV_RUNNING) {
988 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
989
990 if (drv->prepare_flush)
991 return drv->prepare_flush(q, rq);
992 }
993
994 return 0;
995}
996
997static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
998{
999 struct scsi_device *sdev = q->queuedata;
1000 struct request *flush_rq = rq->end_io_data;
1001 struct scsi_driver *drv;
1002
1003 if (flush_rq->errors) {
1004 printk("scsi: barrier error, disabling flush support\n");
1005 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1006 }
1007
1008 if (sdev->sdev_state == SDEV_RUNNING) {
1009 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1010 drv->end_flush(q, rq);
1011 }
1012}
1013
1014static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1015 sector_t *error_sector)
1016{
1017 struct scsi_device *sdev = q->queuedata;
1018 struct scsi_driver *drv;
1019
1020 if (sdev->sdev_state != SDEV_RUNNING)
1021 return -ENXIO;
1022
1023 drv = *(struct scsi_driver **) disk->private_data;
1024 if (drv->issue_flush)
1025 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1026
1027 return -EOPNOTSUPP;
1028}
1029
1030static int scsi_prep_fn(struct request_queue *q, struct request *req)
1031{
1032 struct scsi_device *sdev = q->queuedata;
1033 struct scsi_cmnd *cmd;
1034 int specials_only = 0;
1035
1036 /*
1037 * Just check to see if the device is online. If it isn't, we
1038 * refuse to process any commands. The device must be brought
1039 * online before trying any recovery commands
1040 */
1041 if (unlikely(!scsi_device_online(sdev))) {
1042 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1043 sdev->host->host_no, sdev->id, sdev->lun);
1044 return BLKPREP_KILL;
1045 }
1046 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1047 /* OK, we're not in a running state don't prep
1048 * user commands */
1049 if (sdev->sdev_state == SDEV_DEL) {
1050 /* Device is fully deleted, no commands
1051 * at all allowed down */
1052 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1053 sdev->host->host_no, sdev->id, sdev->lun);
1054 return BLKPREP_KILL;
1055 }
1056 /* OK, we only allow special commands (i.e. not
1057 * user initiated ones */
1058 specials_only = sdev->sdev_state;
1059 }
1060
1061 /*
1062 * Find the actual device driver associated with this command.
1063 * The SPECIAL requests are things like character device or
1064 * ioctls, which did not originate from ll_rw_blk. Note that
1065 * the special field is also used to indicate the cmd for
1066 * the remainder of a partially fulfilled request that can
1067 * come up when there is a medium error. We have to treat
1068 * these two cases differently. We differentiate by looking
1069 * at request->cmd, as this tells us the real story.
1070 */
1071 if (req->flags & REQ_SPECIAL) {
1072 struct scsi_request *sreq = req->special;
1073
1074 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1075 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1076 if (unlikely(!cmd))
1077 goto defer;
1078 scsi_init_cmd_from_req(cmd, sreq);
1079 } else
1080 cmd = req->special;
1081 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1082
1083 if(unlikely(specials_only)) {
1084 if(specials_only == SDEV_QUIESCE ||
1085 specials_only == SDEV_BLOCK)
1086 return BLKPREP_DEFER;
1087
1088 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1089 sdev->host->host_no, sdev->id, sdev->lun);
1090 return BLKPREP_KILL;
1091 }
1092
1093
1094 /*
1095 * Now try and find a command block that we can use.
1096 */
1097 if (!req->special) {
1098 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1099 if (unlikely(!cmd))
1100 goto defer;
1101 } else
1102 cmd = req->special;
1103
1104 /* pull a tag out of the request if we have one */
1105 cmd->tag = req->tag;
1106 } else {
1107 blk_dump_rq_flags(req, "SCSI bad req");
1108 return BLKPREP_KILL;
1109 }
1110
1111 /* note the overloading of req->special. When the tag
1112 * is active it always means cmd. If the tag goes
1113 * back for re-queueing, it may be reset */
1114 req->special = cmd;
1115 cmd->request = req;
1116
1117 /*
1118 * FIXME: drop the lock here because the functions below
1119 * expect to be called without the queue lock held. Also,
1120 * previously, we dequeued the request before dropping the
1121 * lock. We hope REQ_STARTED prevents anything untoward from
1122 * happening now.
1123 */
1124 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1125 struct scsi_driver *drv;
1126 int ret;
1127
1128 /*
1129 * This will do a couple of things:
1130 * 1) Fill in the actual SCSI command.
1131 * 2) Fill in any other upper-level specific fields
1132 * (timeout).
1133 *
1134 * If this returns 0, it means that the request failed
1135 * (reading past end of disk, reading offline device,
1136 * etc). This won't actually talk to the device, but
1137 * some kinds of consistency checking may cause the
1138 * request to be rejected immediately.
1139 */
1140
1141 /*
1142 * This sets up the scatter-gather table (allocating if
1143 * required).
1144 */
1145 ret = scsi_init_io(cmd);
1146 if (ret) /* BLKPREP_KILL return also releases the command */
1147 return ret;
1148
1149 /*
1150 * Initialize the actual SCSI command for this request.
1151 */
1152 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1153 if (unlikely(!drv->init_command(cmd))) {
1154 scsi_release_buffers(cmd);
1155 scsi_put_command(cmd);
1156 return BLKPREP_KILL;
1157 }
1158 }
1159
1160 /*
1161 * The request is now prepped, no need to come back here
1162 */
1163 req->flags |= REQ_DONTPREP;
1164 return BLKPREP_OK;
1165
1166 defer:
1167 /* If we defer, the elv_next_request() returns NULL, but the
1168 * queue must be restarted, so we plug here if no returning
1169 * command will automatically do that. */
1170 if (sdev->device_busy == 0)
1171 blk_plug_device(q);
1172 return BLKPREP_DEFER;
1173}
1174
1175/*
1176 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1177 * return 0.
1178 *
1179 * Called with the queue_lock held.
1180 */
1181static inline int scsi_dev_queue_ready(struct request_queue *q,
1182 struct scsi_device *sdev)
1183{
1184 if (sdev->device_busy >= sdev->queue_depth)
1185 return 0;
1186 if (sdev->device_busy == 0 && sdev->device_blocked) {
1187 /*
1188 * unblock after device_blocked iterates to zero
1189 */
1190 if (--sdev->device_blocked == 0) {
1191 SCSI_LOG_MLQUEUE(3,
1192 printk("scsi%d (%d:%d) unblocking device at"
1193 " zero depth\n", sdev->host->host_no,
1194 sdev->id, sdev->lun));
1195 } else {
1196 blk_plug_device(q);
1197 return 0;
1198 }
1199 }
1200 if (sdev->device_blocked)
1201 return 0;
1202
1203 return 1;
1204}
1205
1206/*
1207 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1208 * return 0. We must end up running the queue again whenever 0 is
1209 * returned, else IO can hang.
1210 *
1211 * Called with host_lock held.
1212 */
1213static inline int scsi_host_queue_ready(struct request_queue *q,
1214 struct Scsi_Host *shost,
1215 struct scsi_device *sdev)
1216{
1217 if (test_bit(SHOST_RECOVERY, &shost->shost_state))
1218 return 0;
1219 if (shost->host_busy == 0 && shost->host_blocked) {
1220 /*
1221 * unblock after host_blocked iterates to zero
1222 */
1223 if (--shost->host_blocked == 0) {
1224 SCSI_LOG_MLQUEUE(3,
1225 printk("scsi%d unblocking host at zero depth\n",
1226 shost->host_no));
1227 } else {
1228 blk_plug_device(q);
1229 return 0;
1230 }
1231 }
1232 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1233 shost->host_blocked || shost->host_self_blocked) {
1234 if (list_empty(&sdev->starved_entry))
1235 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1236 return 0;
1237 }
1238
1239 /* We're OK to process the command, so we can't be starved */
1240 if (!list_empty(&sdev->starved_entry))
1241 list_del_init(&sdev->starved_entry);
1242
1243 return 1;
1244}
1245
1246/*
1247 * Kill requests for a dead device
1248 */
1249static void scsi_kill_requests(request_queue_t *q)
1250{
1251 struct request *req;
1252
1253 while ((req = elv_next_request(q)) != NULL) {
1254 blkdev_dequeue_request(req);
1255 req->flags |= REQ_QUIET;
1256 while (end_that_request_first(req, 0, req->nr_sectors))
1257 ;
1258 end_that_request_last(req);
1259 }
1260}
1261
1262/*
1263 * Function: scsi_request_fn()
1264 *
1265 * Purpose: Main strategy routine for SCSI.
1266 *
1267 * Arguments: q - Pointer to actual queue.
1268 *
1269 * Returns: Nothing
1270 *
1271 * Lock status: IO request lock assumed to be held when called.
1272 */
1273static void scsi_request_fn(struct request_queue *q)
1274{
1275 struct scsi_device *sdev = q->queuedata;
1276 struct Scsi_Host *shost;
1277 struct scsi_cmnd *cmd;
1278 struct request *req;
1279
1280 if (!sdev) {
1281 printk("scsi: killing requests for dead queue\n");
1282 scsi_kill_requests(q);
1283 return;
1284 }
1285
1286 if(!get_device(&sdev->sdev_gendev))
1287 /* We must be tearing the block queue down already */
1288 return;
1289
1290 /*
1291 * To start with, we keep looping until the queue is empty, or until
1292 * the host is no longer able to accept any more requests.
1293 */
1294 shost = sdev->host;
1295 while (!blk_queue_plugged(q)) {
1296 int rtn;
1297 /*
1298 * get next queueable request. We do this early to make sure
1299 * that the request is fully prepared even if we cannot
1300 * accept it.
1301 */
1302 req = elv_next_request(q);
1303 if (!req || !scsi_dev_queue_ready(q, sdev))
1304 break;
1305
1306 if (unlikely(!scsi_device_online(sdev))) {
1307 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1308 sdev->host->host_no, sdev->id, sdev->lun);
1309 blkdev_dequeue_request(req);
1310 req->flags |= REQ_QUIET;
1311 while (end_that_request_first(req, 0, req->nr_sectors))
1312 ;
1313 end_that_request_last(req);
1314 continue;
1315 }
1316
1317
1318 /*
1319 * Remove the request from the request list.
1320 */
1321 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1322 blkdev_dequeue_request(req);
1323 sdev->device_busy++;
1324
1325 spin_unlock(q->queue_lock);
1326 spin_lock(shost->host_lock);
1327
1328 if (!scsi_host_queue_ready(q, shost, sdev))
1329 goto not_ready;
1330 if (sdev->single_lun) {
1331 if (scsi_target(sdev)->starget_sdev_user &&
1332 scsi_target(sdev)->starget_sdev_user != sdev)
1333 goto not_ready;
1334 scsi_target(sdev)->starget_sdev_user = sdev;
1335 }
1336 shost->host_busy++;
1337
1338 /*
1339 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1340 * take the lock again.
1341 */
1342 spin_unlock_irq(shost->host_lock);
1343
1344 cmd = req->special;
1345 if (unlikely(cmd == NULL)) {
1346 printk(KERN_CRIT "impossible request in %s.\n"
1347 "please mail a stack trace to "
1348 "linux-scsi@vger.kernel.org",
1349 __FUNCTION__);
1350 BUG();
1351 }
1352
1353 /*
1354 * Finally, initialize any error handling parameters, and set up
1355 * the timers for timeouts.
1356 */
1357 scsi_init_cmd_errh(cmd);
1358
1359 /*
1360 * Dispatch the command to the low-level driver.
1361 */
1362 rtn = scsi_dispatch_cmd(cmd);
1363 spin_lock_irq(q->queue_lock);
1364 if(rtn) {
1365 /* we're refusing the command; because of
1366 * the way locks get dropped, we need to
1367 * check here if plugging is required */
1368 if(sdev->device_busy == 0)
1369 blk_plug_device(q);
1370
1371 break;
1372 }
1373 }
1374
1375 goto out;
1376
1377 not_ready:
1378 spin_unlock_irq(shost->host_lock);
1379
1380 /*
1381 * lock q, handle tag, requeue req, and decrement device_busy. We
1382 * must return with queue_lock held.
1383 *
1384 * Decrementing device_busy without checking it is OK, as all such
1385 * cases (host limits or settings) should run the queue at some
1386 * later time.
1387 */
1388 spin_lock_irq(q->queue_lock);
1389 blk_requeue_request(q, req);
1390 sdev->device_busy--;
1391 if(sdev->device_busy == 0)
1392 blk_plug_device(q);
1393 out:
1394 /* must be careful here...if we trigger the ->remove() function
1395 * we cannot be holding the q lock */
1396 spin_unlock_irq(q->queue_lock);
1397 put_device(&sdev->sdev_gendev);
1398 spin_lock_irq(q->queue_lock);
1399}
1400
1401u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1402{
1403 struct device *host_dev;
1404 u64 bounce_limit = 0xffffffff;
1405
1406 if (shost->unchecked_isa_dma)
1407 return BLK_BOUNCE_ISA;
1408 /*
1409 * Platforms with virtual-DMA translation
1410 * hardware have no practical limit.
1411 */
1412 if (!PCI_DMA_BUS_IS_PHYS)
1413 return BLK_BOUNCE_ANY;
1414
1415 host_dev = scsi_get_device(shost);
1416 if (host_dev && host_dev->dma_mask)
1417 bounce_limit = *host_dev->dma_mask;
1418
1419 return bounce_limit;
1420}
1421EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1422
1423struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1424{
1425 struct Scsi_Host *shost = sdev->host;
1426 struct request_queue *q;
1427
1428 q = blk_init_queue(scsi_request_fn, &sdev->sdev_lock);
1429 if (!q)
1430 return NULL;
1431
1432 blk_queue_prep_rq(q, scsi_prep_fn);
1433
1434 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1435 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1436 blk_queue_max_sectors(q, shost->max_sectors);
1437 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1438 blk_queue_segment_boundary(q, shost->dma_boundary);
1439 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1440
1441 /*
1442 * ordered tags are superior to flush ordering
1443 */
1444 if (shost->ordered_tag)
1445 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1446 else if (shost->ordered_flush) {
1447 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1448 q->prepare_flush_fn = scsi_prepare_flush_fn;
1449 q->end_flush_fn = scsi_end_flush_fn;
1450 }
1451
1452 if (!shost->use_clustering)
1453 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1454 return q;
1455}
1456
1457void scsi_free_queue(struct request_queue *q)
1458{
1459 blk_cleanup_queue(q);
1460}
1461
1462/*
1463 * Function: scsi_block_requests()
1464 *
1465 * Purpose: Utility function used by low-level drivers to prevent further
1466 * commands from being queued to the device.
1467 *
1468 * Arguments: shost - Host in question
1469 *
1470 * Returns: Nothing
1471 *
1472 * Lock status: No locks are assumed held.
1473 *
1474 * Notes: There is no timer nor any other means by which the requests
1475 * get unblocked other than the low-level driver calling
1476 * scsi_unblock_requests().
1477 */
1478void scsi_block_requests(struct Scsi_Host *shost)
1479{
1480 shost->host_self_blocked = 1;
1481}
1482EXPORT_SYMBOL(scsi_block_requests);
1483
1484/*
1485 * Function: scsi_unblock_requests()
1486 *
1487 * Purpose: Utility function used by low-level drivers to allow further
1488 * commands from being queued to the device.
1489 *
1490 * Arguments: shost - Host in question
1491 *
1492 * Returns: Nothing
1493 *
1494 * Lock status: No locks are assumed held.
1495 *
1496 * Notes: There is no timer nor any other means by which the requests
1497 * get unblocked other than the low-level driver calling
1498 * scsi_unblock_requests().
1499 *
1500 * This is done as an API function so that changes to the
1501 * internals of the scsi mid-layer won't require wholesale
1502 * changes to drivers that use this feature.
1503 */
1504void scsi_unblock_requests(struct Scsi_Host *shost)
1505{
1506 shost->host_self_blocked = 0;
1507 scsi_run_host_queues(shost);
1508}
1509EXPORT_SYMBOL(scsi_unblock_requests);
1510
1511int __init scsi_init_queue(void)
1512{
1513 int i;
1514
1515 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1516 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1517 int size = sgp->size * sizeof(struct scatterlist);
1518
1519 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1520 SLAB_HWCACHE_ALIGN, NULL, NULL);
1521 if (!sgp->slab) {
1522 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1523 sgp->name);
1524 }
1525
1526 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1527 mempool_alloc_slab, mempool_free_slab,
1528 sgp->slab);
1529 if (!sgp->pool) {
1530 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1531 sgp->name);
1532 }
1533 }
1534
1535 return 0;
1536}
1537
1538void scsi_exit_queue(void)
1539{
1540 int i;
1541
1542 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1543 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1544 mempool_destroy(sgp->pool);
1545 kmem_cache_destroy(sgp->slab);
1546 }
1547}
1548/**
1549 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1550 * six bytes if necessary.
1551 * @sreq: SCSI request to fill in with the MODE_SENSE
1552 * @dbd: set if mode sense will allow block descriptors to be returned
1553 * @modepage: mode page being requested
1554 * @buffer: request buffer (may not be smaller than eight bytes)
1555 * @len: length of request buffer.
1556 * @timeout: command timeout
1557 * @retries: number of retries before failing
1558 * @data: returns a structure abstracting the mode header data
1559 *
1560 * Returns zero if unsuccessful, or the header offset (either 4
1561 * or 8 depending on whether a six or ten byte command was
1562 * issued) if successful.
1563 **/
1564int
1565__scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
1566 unsigned char *buffer, int len, int timeout, int retries,
1567 struct scsi_mode_data *data) {
1568 unsigned char cmd[12];
1569 int use_10_for_ms;
1570 int header_length;
1571
1572 memset(data, 0, sizeof(*data));
1573 memset(&cmd[0], 0, 12);
1574 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1575 cmd[2] = modepage;
1576
1577 retry:
1578 use_10_for_ms = sreq->sr_device->use_10_for_ms;
1579
1580 if (use_10_for_ms) {
1581 if (len < 8)
1582 len = 8;
1583
1584 cmd[0] = MODE_SENSE_10;
1585 cmd[8] = len;
1586 header_length = 8;
1587 } else {
1588 if (len < 4)
1589 len = 4;
1590
1591 cmd[0] = MODE_SENSE;
1592 cmd[4] = len;
1593 header_length = 4;
1594 }
1595
1596 sreq->sr_cmd_len = 0;
1597 memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
1598 sreq->sr_data_direction = DMA_FROM_DEVICE;
1599
1600 memset(buffer, 0, len);
1601
1602 scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
1603
1604 /* This code looks awful: what it's doing is making sure an
1605 * ILLEGAL REQUEST sense return identifies the actual command
1606 * byte as the problem. MODE_SENSE commands can return
1607 * ILLEGAL REQUEST if the code page isn't supported */
1608
1609 if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
1610 (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
1611 struct scsi_sense_hdr sshdr;
1612
1613 if (scsi_request_normalize_sense(sreq, &sshdr)) {
1614 if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
1615 (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
1616 /*
1617 * Invalid command operation code
1618 */
1619 sreq->sr_device->use_10_for_ms = 0;
1620 goto retry;
1621 }
1622 }
1623 }
1624
1625 if(scsi_status_is_good(sreq->sr_result)) {
1626 data->header_length = header_length;
1627 if(use_10_for_ms) {
1628 data->length = buffer[0]*256 + buffer[1] + 2;
1629 data->medium_type = buffer[2];
1630 data->device_specific = buffer[3];
1631 data->longlba = buffer[4] & 0x01;
1632 data->block_descriptor_length = buffer[6]*256
1633 + buffer[7];
1634 } else {
1635 data->length = buffer[0] + 1;
1636 data->medium_type = buffer[1];
1637 data->device_specific = buffer[2];
1638 data->block_descriptor_length = buffer[3];
1639 }
1640 }
1641
1642 return sreq->sr_result;
1643}
1644EXPORT_SYMBOL(__scsi_mode_sense);
1645
1646/**
1647 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1648 * six bytes if necessary.
1649 * @sdev: scsi device to send command to.
1650 * @dbd: set if mode sense will disable block descriptors in the return
1651 * @modepage: mode page being requested
1652 * @buffer: request buffer (may not be smaller than eight bytes)
1653 * @len: length of request buffer.
1654 * @timeout: command timeout
1655 * @retries: number of retries before failing
1656 *
1657 * Returns zero if unsuccessful, or the header offset (either 4
1658 * or 8 depending on whether a six or ten byte command was
1659 * issued) if successful.
1660 **/
1661int
1662scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1663 unsigned char *buffer, int len, int timeout, int retries,
1664 struct scsi_mode_data *data)
1665{
1666 struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1667 int ret;
1668
1669 if (!sreq)
1670 return -1;
1671
1672 ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
1673 timeout, retries, data);
1674
1675 scsi_release_request(sreq);
1676
1677 return ret;
1678}
1679EXPORT_SYMBOL(scsi_mode_sense);
1680
1681int
1682scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1683{
1684 struct scsi_request *sreq;
1685 char cmd[] = {
1686 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1687 };
1688 int result;
1689
1690 sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1691 if (!sreq)
1692 return -ENOMEM;
1693
1694 sreq->sr_data_direction = DMA_NONE;
1695 scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
1696
1697 if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
1698 struct scsi_sense_hdr sshdr;
1699
1700 if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
1701 ((sshdr.sense_key == UNIT_ATTENTION) ||
1702 (sshdr.sense_key == NOT_READY))) {
1703 sdev->changed = 1;
1704 sreq->sr_result = 0;
1705 }
1706 }
1707 result = sreq->sr_result;
1708 scsi_release_request(sreq);
1709 return result;
1710}
1711EXPORT_SYMBOL(scsi_test_unit_ready);
1712
1713/**
1714 * scsi_device_set_state - Take the given device through the device
1715 * state model.
1716 * @sdev: scsi device to change the state of.
1717 * @state: state to change to.
1718 *
1719 * Returns zero if unsuccessful or an error if the requested
1720 * transition is illegal.
1721 **/
1722int
1723scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1724{
1725 enum scsi_device_state oldstate = sdev->sdev_state;
1726
1727 if (state == oldstate)
1728 return 0;
1729
1730 switch (state) {
1731 case SDEV_CREATED:
1732 /* There are no legal states that come back to
1733 * created. This is the manually initialised start
1734 * state */
1735 goto illegal;
1736
1737 case SDEV_RUNNING:
1738 switch (oldstate) {
1739 case SDEV_CREATED:
1740 case SDEV_OFFLINE:
1741 case SDEV_QUIESCE:
1742 case SDEV_BLOCK:
1743 break;
1744 default:
1745 goto illegal;
1746 }
1747 break;
1748
1749 case SDEV_QUIESCE:
1750 switch (oldstate) {
1751 case SDEV_RUNNING:
1752 case SDEV_OFFLINE:
1753 break;
1754 default:
1755 goto illegal;
1756 }
1757 break;
1758
1759 case SDEV_OFFLINE:
1760 switch (oldstate) {
1761 case SDEV_CREATED:
1762 case SDEV_RUNNING:
1763 case SDEV_QUIESCE:
1764 case SDEV_BLOCK:
1765 break;
1766 default:
1767 goto illegal;
1768 }
1769 break;
1770
1771 case SDEV_BLOCK:
1772 switch (oldstate) {
1773 case SDEV_CREATED:
1774 case SDEV_RUNNING:
1775 break;
1776 default:
1777 goto illegal;
1778 }
1779 break;
1780
1781 case SDEV_CANCEL:
1782 switch (oldstate) {
1783 case SDEV_CREATED:
1784 case SDEV_RUNNING:
1785 case SDEV_OFFLINE:
1786 case SDEV_BLOCK:
1787 break;
1788 default:
1789 goto illegal;
1790 }
1791 break;
1792
1793 case SDEV_DEL:
1794 switch (oldstate) {
1795 case SDEV_CANCEL:
1796 break;
1797 default:
1798 goto illegal;
1799 }
1800 break;
1801
1802 }
1803 sdev->sdev_state = state;
1804 return 0;
1805
1806 illegal:
1807 SCSI_LOG_ERROR_RECOVERY(1,
1808 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1809 "Illegal state transition %s->%s\n",
1810 scsi_device_state_name(oldstate),
1811 scsi_device_state_name(state))
1812 );
1813 return -EINVAL;
1814}
1815EXPORT_SYMBOL(scsi_device_set_state);
1816
1817/**
1818 * scsi_device_quiesce - Block user issued commands.
1819 * @sdev: scsi device to quiesce.
1820 *
1821 * This works by trying to transition to the SDEV_QUIESCE state
1822 * (which must be a legal transition). When the device is in this
1823 * state, only special requests will be accepted, all others will
1824 * be deferred. Since special requests may also be requeued requests,
1825 * a successful return doesn't guarantee the device will be
1826 * totally quiescent.
1827 *
1828 * Must be called with user context, may sleep.
1829 *
1830 * Returns zero if unsuccessful or an error if not.
1831 **/
1832int
1833scsi_device_quiesce(struct scsi_device *sdev)
1834{
1835 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1836 if (err)
1837 return err;
1838
1839 scsi_run_queue(sdev->request_queue);
1840 while (sdev->device_busy) {
1841 msleep_interruptible(200);
1842 scsi_run_queue(sdev->request_queue);
1843 }
1844 return 0;
1845}
1846EXPORT_SYMBOL(scsi_device_quiesce);
1847
1848/**
1849 * scsi_device_resume - Restart user issued commands to a quiesced device.
1850 * @sdev: scsi device to resume.
1851 *
1852 * Moves the device from quiesced back to running and restarts the
1853 * queues.
1854 *
1855 * Must be called with user context, may sleep.
1856 **/
1857void
1858scsi_device_resume(struct scsi_device *sdev)
1859{
1860 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1861 return;
1862 scsi_run_queue(sdev->request_queue);
1863}
1864EXPORT_SYMBOL(scsi_device_resume);
1865
1866static void
1867device_quiesce_fn(struct scsi_device *sdev, void *data)
1868{
1869 scsi_device_quiesce(sdev);
1870}
1871
1872void
1873scsi_target_quiesce(struct scsi_target *starget)
1874{
1875 starget_for_each_device(starget, NULL, device_quiesce_fn);
1876}
1877EXPORT_SYMBOL(scsi_target_quiesce);
1878
1879static void
1880device_resume_fn(struct scsi_device *sdev, void *data)
1881{
1882 scsi_device_resume(sdev);
1883}
1884
1885void
1886scsi_target_resume(struct scsi_target *starget)
1887{
1888 starget_for_each_device(starget, NULL, device_resume_fn);
1889}
1890EXPORT_SYMBOL(scsi_target_resume);
1891
1892/**
1893 * scsi_internal_device_block - internal function to put a device
1894 * temporarily into the SDEV_BLOCK state
1895 * @sdev: device to block
1896 *
1897 * Block request made by scsi lld's to temporarily stop all
1898 * scsi commands on the specified device. Called from interrupt
1899 * or normal process context.
1900 *
1901 * Returns zero if successful or error if not
1902 *
1903 * Notes:
1904 * This routine transitions the device to the SDEV_BLOCK state
1905 * (which must be a legal transition). When the device is in this
1906 * state, all commands are deferred until the scsi lld reenables
1907 * the device with scsi_device_unblock or device_block_tmo fires.
1908 * This routine assumes the host_lock is held on entry.
1909 **/
1910int
1911scsi_internal_device_block(struct scsi_device *sdev)
1912{
1913 request_queue_t *q = sdev->request_queue;
1914 unsigned long flags;
1915 int err = 0;
1916
1917 err = scsi_device_set_state(sdev, SDEV_BLOCK);
1918 if (err)
1919 return err;
1920
1921 /*
1922 * The device has transitioned to SDEV_BLOCK. Stop the
1923 * block layer from calling the midlayer with this device's
1924 * request queue.
1925 */
1926 spin_lock_irqsave(q->queue_lock, flags);
1927 blk_stop_queue(q);
1928 spin_unlock_irqrestore(q->queue_lock, flags);
1929
1930 return 0;
1931}
1932EXPORT_SYMBOL_GPL(scsi_internal_device_block);
1933
1934/**
1935 * scsi_internal_device_unblock - resume a device after a block request
1936 * @sdev: device to resume
1937 *
1938 * Called by scsi lld's or the midlayer to restart the device queue
1939 * for the previously suspended scsi device. Called from interrupt or
1940 * normal process context.
1941 *
1942 * Returns zero if successful or error if not.
1943 *
1944 * Notes:
1945 * This routine transitions the device to the SDEV_RUNNING state
1946 * (which must be a legal transition) allowing the midlayer to
1947 * goose the queue for this device. This routine assumes the
1948 * host_lock is held upon entry.
1949 **/
1950int
1951scsi_internal_device_unblock(struct scsi_device *sdev)
1952{
1953 request_queue_t *q = sdev->request_queue;
1954 int err;
1955 unsigned long flags;
1956
1957 /*
1958 * Try to transition the scsi device to SDEV_RUNNING
1959 * and goose the device queue if successful.
1960 */
1961 err = scsi_device_set_state(sdev, SDEV_RUNNING);
1962 if (err)
1963 return err;
1964
1965 spin_lock_irqsave(q->queue_lock, flags);
1966 blk_start_queue(q);
1967 spin_unlock_irqrestore(q->queue_lock, flags);
1968
1969 return 0;
1970}
1971EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
1972
1973static void
1974device_block(struct scsi_device *sdev, void *data)
1975{
1976 scsi_internal_device_block(sdev);
1977}
1978
1979static int
1980target_block(struct device *dev, void *data)
1981{
1982 if (scsi_is_target_device(dev))
1983 starget_for_each_device(to_scsi_target(dev), NULL,
1984 device_block);
1985 return 0;
1986}
1987
1988void
1989scsi_target_block(struct device *dev)
1990{
1991 if (scsi_is_target_device(dev))
1992 starget_for_each_device(to_scsi_target(dev), NULL,
1993 device_block);
1994 else
1995 device_for_each_child(dev, NULL, target_block);
1996}
1997EXPORT_SYMBOL_GPL(scsi_target_block);
1998
1999static void
2000device_unblock(struct scsi_device *sdev, void *data)
2001{
2002 scsi_internal_device_unblock(sdev);
2003}
2004
2005static int
2006target_unblock(struct device *dev, void *data)
2007{
2008 if (scsi_is_target_device(dev))
2009 starget_for_each_device(to_scsi_target(dev), NULL,
2010 device_unblock);
2011 return 0;
2012}
2013
2014void
2015scsi_target_unblock(struct device *dev)
2016{
2017 if (scsi_is_target_device(dev))
2018 starget_for_each_device(to_scsi_target(dev), NULL,
2019 device_unblock);
2020 else
2021 device_for_each_child(dev, NULL, target_unblock);
2022}
2023EXPORT_SYMBOL_GPL(scsi_target_unblock);
generated by cgit v1.2.2 (git 2.25.0) at 2025-11-09 09:07:46 -0500