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1da177e4 LT |
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 | ||
35 | struct 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 } | |
47 | struct 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 | */ | |
87 | int 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 | */ | |
118 | int 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 | */ | |
203 | void 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 | } | |
236 | EXPORT_SYMBOL(scsi_do_req); | |
237 | ||
238 | static 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. */ | |
258 | static void scsi_wait_req_end_io(struct request *req) | |
259 | { | |
260 | BUG_ON(!req->waiting); | |
261 | ||
262 | complete(req->waiting); | |
263 | } | |
264 | ||
265 | void 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 | } | |
282 | EXPORT_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 | */ | |
297 | static 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 | */ | |
341 | void 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 | ||
352 | void 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 | */ | |
375 | static 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 | */ | |
426 | static 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 | */ | |
488 | static 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 | ||
496 | void 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 | ||
504 | void 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 | */ | |
533 | static 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 | ||
582 | static 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 | ||
625 | static 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 | */ | |
652 | static 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 | */ | |
702 | void 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 | } | |
905 | EXPORT_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 | */ | |
918 | static 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 | ||
982 | static 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 | ||
997 | static 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 | ||
1014 | static 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 | ||
1030 | static 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 | */ | |
1181 | static 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 | */ | |
1213 | static 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 | */ | |
1249 | static 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 | */ | |
1273 | static 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 | ||
1401 | u64 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 | } | |
1421 | EXPORT_SYMBOL(scsi_calculate_bounce_limit); | |
1422 | ||
1423 | struct 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 | ||
1457 | void 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 | */ | |
1478 | void scsi_block_requests(struct Scsi_Host *shost) | |
1479 | { | |
1480 | shost->host_self_blocked = 1; | |
1481 | } | |
1482 | EXPORT_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 | */ | |
1504 | void scsi_unblock_requests(struct Scsi_Host *shost) | |
1505 | { | |
1506 | shost->host_self_blocked = 0; | |
1507 | scsi_run_host_queues(shost); | |
1508 | } | |
1509 | EXPORT_SYMBOL(scsi_unblock_requests); | |
1510 | ||
1511 | int __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 | ||
1538 | void 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 | **/ | |
1564 | int | |
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 | } | |
1644 | EXPORT_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 | **/ | |
1661 | int | |
1662 | scsi_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 | } | |
1679 | EXPORT_SYMBOL(scsi_mode_sense); | |
1680 | ||
1681 | int | |
1682 | scsi_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 | } | |
1711 | EXPORT_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 | **/ | |
1722 | int | |
1723 | scsi_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 | } | |
1815 | EXPORT_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 | **/ | |
1832 | int | |
1833 | scsi_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 | } | |
1846 | EXPORT_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 | **/ | |
1857 | void | |
1858 | scsi_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 | } | |
1864 | EXPORT_SYMBOL(scsi_device_resume); | |
1865 | ||
1866 | static void | |
1867 | device_quiesce_fn(struct scsi_device *sdev, void *data) | |
1868 | { | |
1869 | scsi_device_quiesce(sdev); | |
1870 | } | |
1871 | ||
1872 | void | |
1873 | scsi_target_quiesce(struct scsi_target *starget) | |
1874 | { | |
1875 | starget_for_each_device(starget, NULL, device_quiesce_fn); | |
1876 | } | |
1877 | EXPORT_SYMBOL(scsi_target_quiesce); | |
1878 | ||
1879 | static void | |
1880 | device_resume_fn(struct scsi_device *sdev, void *data) | |
1881 | { | |
1882 | scsi_device_resume(sdev); | |
1883 | } | |
1884 | ||
1885 | void | |
1886 | scsi_target_resume(struct scsi_target *starget) | |
1887 | { | |
1888 | starget_for_each_device(starget, NULL, device_resume_fn); | |
1889 | } | |
1890 | EXPORT_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 | **/ | |
1910 | int | |
1911 | scsi_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 | } | |
1932 | EXPORT_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 | **/ | |
1950 | int | |
1951 | scsi_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 | } | |
1971 | EXPORT_SYMBOL_GPL(scsi_internal_device_unblock); | |
1972 | ||
1973 | static void | |
1974 | device_block(struct scsi_device *sdev, void *data) | |
1975 | { | |
1976 | scsi_internal_device_block(sdev); | |
1977 | } | |
1978 | ||
1979 | static int | |
1980 | target_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 | ||
1988 | void | |
1989 | scsi_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 | } | |
1997 | EXPORT_SYMBOL_GPL(scsi_target_block); | |
1998 | ||
1999 | static void | |
2000 | device_unblock(struct scsi_device *sdev, void *data) | |
2001 | { | |
2002 | scsi_internal_device_unblock(sdev); | |
2003 | } | |
2004 | ||
2005 | static int | |
2006 | target_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 | ||
2014 | void | |
2015 | scsi_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 | } | |
2023 | EXPORT_SYMBOL_GPL(scsi_target_unblock); |