RS485: fix inconsistencies in the meaning of some variables
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / scsi / scsi_lib.c
blob06bc26554a67359a8656ef976b6d483e71bfd0fb
1 /*
2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
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 */
10 #include <linux/bio.h>
11 #include <linux/bitops.h>
12 #include <linux/blkdev.h>
13 #include <linux/completion.h>
14 #include <linux/kernel.h>
15 #include <linux/export.h>
16 #include <linux/mempool.h>
17 #include <linux/slab.h>
18 #include <linux/init.h>
19 #include <linux/pci.h>
20 #include <linux/delay.h>
21 #include <linux/hardirq.h>
22 #include <linux/scatterlist.h>
24 #include <scsi/scsi.h>
25 #include <scsi/scsi_cmnd.h>
26 #include <scsi/scsi_dbg.h>
27 #include <scsi/scsi_device.h>
28 #include <scsi/scsi_driver.h>
29 #include <scsi/scsi_eh.h>
30 #include <scsi/scsi_host.h>
32 #include "scsi_priv.h"
33 #include "scsi_logging.h"
36 #define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
37 #define SG_MEMPOOL_SIZE 2
39 struct scsi_host_sg_pool {
40 size_t size;
41 char *name;
42 struct kmem_cache *slab;
43 mempool_t *pool;
46 #define SP(x) { x, "sgpool-" __stringify(x) }
47 #if (SCSI_MAX_SG_SEGMENTS < 32)
48 #error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
49 #endif
50 static struct scsi_host_sg_pool scsi_sg_pools[] = {
51 SP(8),
52 SP(16),
53 #if (SCSI_MAX_SG_SEGMENTS > 32)
54 SP(32),
55 #if (SCSI_MAX_SG_SEGMENTS > 64)
56 SP(64),
57 #if (SCSI_MAX_SG_SEGMENTS > 128)
58 SP(128),
59 #if (SCSI_MAX_SG_SEGMENTS > 256)
60 #error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
61 #endif
62 #endif
63 #endif
64 #endif
65 SP(SCSI_MAX_SG_SEGMENTS)
67 #undef SP
69 struct kmem_cache *scsi_sdb_cache;
72 * When to reinvoke queueing after a resource shortage. It's 3 msecs to
73 * not change behaviour from the previous unplug mechanism, experimentation
74 * may prove this needs changing.
76 #define SCSI_QUEUE_DELAY 3
79 * Function: scsi_unprep_request()
81 * Purpose: Remove all preparation done for a request, including its
82 * associated scsi_cmnd, so that it can be requeued.
84 * Arguments: req - request to unprepare
86 * Lock status: Assumed that no locks are held upon entry.
88 * Returns: Nothing.
90 static void scsi_unprep_request(struct request *req)
92 struct scsi_cmnd *cmd = req->special;
94 blk_unprep_request(req);
95 req->special = NULL;
97 scsi_put_command(cmd);
101 * __scsi_queue_insert - private queue insertion
102 * @cmd: The SCSI command being requeued
103 * @reason: The reason for the requeue
104 * @unbusy: Whether the queue should be unbusied
106 * This is a private queue insertion. The public interface
107 * scsi_queue_insert() always assumes the queue should be unbusied
108 * because it's always called before the completion. This function is
109 * for a requeue after completion, which should only occur in this
110 * file.
112 static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
114 struct Scsi_Host *host = cmd->device->host;
115 struct scsi_device *device = cmd->device;
116 struct scsi_target *starget = scsi_target(device);
117 struct request_queue *q = device->request_queue;
118 unsigned long flags;
120 SCSI_LOG_MLQUEUE(1,
121 printk("Inserting command %p into mlqueue\n", cmd));
124 * Set the appropriate busy bit for the device/host.
126 * If the host/device isn't busy, assume that something actually
127 * completed, and that we should be able to queue a command now.
129 * Note that the prior mid-layer assumption that any host could
130 * always queue at least one command is now broken. The mid-layer
131 * will implement a user specifiable stall (see
132 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
133 * if a command is requeued with no other commands outstanding
134 * either for the device or for the host.
136 switch (reason) {
137 case SCSI_MLQUEUE_HOST_BUSY:
138 host->host_blocked = host->max_host_blocked;
139 break;
140 case SCSI_MLQUEUE_DEVICE_BUSY:
141 case SCSI_MLQUEUE_EH_RETRY:
142 device->device_blocked = device->max_device_blocked;
143 break;
144 case SCSI_MLQUEUE_TARGET_BUSY:
145 starget->target_blocked = starget->max_target_blocked;
146 break;
150 * Decrement the counters, since these commands are no longer
151 * active on the host/device.
153 if (unbusy)
154 scsi_device_unbusy(device);
157 * Requeue this command. It will go before all other commands
158 * that are already in the queue.
160 spin_lock_irqsave(q->queue_lock, flags);
161 blk_requeue_request(q, cmd->request);
162 spin_unlock_irqrestore(q->queue_lock, flags);
164 kblockd_schedule_work(q, &device->requeue_work);
166 return 0;
170 * Function: scsi_queue_insert()
172 * Purpose: Insert a command in the midlevel queue.
174 * Arguments: cmd - command that we are adding to queue.
175 * reason - why we are inserting command to queue.
177 * Lock status: Assumed that lock is not held upon entry.
179 * Returns: Nothing.
181 * Notes: We do this for one of two cases. Either the host is busy
182 * and it cannot accept any more commands for the time being,
183 * or the device returned QUEUE_FULL and can accept no more
184 * commands.
185 * Notes: This could be called either from an interrupt context or a
186 * normal process context.
188 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
190 return __scsi_queue_insert(cmd, reason, 1);
193 * scsi_execute - insert request and wait for the result
194 * @sdev: scsi device
195 * @cmd: scsi command
196 * @data_direction: data direction
197 * @buffer: data buffer
198 * @bufflen: len of buffer
199 * @sense: optional sense buffer
200 * @timeout: request timeout in seconds
201 * @retries: number of times to retry request
202 * @flags: or into request flags;
203 * @resid: optional residual length
205 * returns the req->errors value which is the scsi_cmnd result
206 * field.
208 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
209 int data_direction, void *buffer, unsigned bufflen,
210 unsigned char *sense, int timeout, int retries, int flags,
211 int *resid)
213 struct request *req;
214 int write = (data_direction == DMA_TO_DEVICE);
215 int ret = DRIVER_ERROR << 24;
217 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
218 if (!req)
219 return ret;
221 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
222 buffer, bufflen, __GFP_WAIT))
223 goto out;
225 req->cmd_len = COMMAND_SIZE(cmd[0]);
226 memcpy(req->cmd, cmd, req->cmd_len);
227 req->sense = sense;
228 req->sense_len = 0;
229 req->retries = retries;
230 req->timeout = timeout;
231 req->cmd_type = REQ_TYPE_BLOCK_PC;
232 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
235 * head injection *required* here otherwise quiesce won't work
237 blk_execute_rq(req->q, NULL, req, 1);
240 * Some devices (USB mass-storage in particular) may transfer
241 * garbage data together with a residue indicating that the data
242 * is invalid. Prevent the garbage from being misinterpreted
243 * and prevent security leaks by zeroing out the excess data.
245 if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
246 memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
248 if (resid)
249 *resid = req->resid_len;
250 ret = req->errors;
251 out:
252 blk_put_request(req);
254 return ret;
256 EXPORT_SYMBOL(scsi_execute);
259 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
260 int data_direction, void *buffer, unsigned bufflen,
261 struct scsi_sense_hdr *sshdr, int timeout, int retries,
262 int *resid)
264 char *sense = NULL;
265 int result;
267 if (sshdr) {
268 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
269 if (!sense)
270 return DRIVER_ERROR << 24;
272 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
273 sense, timeout, retries, 0, resid);
274 if (sshdr)
275 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
277 kfree(sense);
278 return result;
280 EXPORT_SYMBOL(scsi_execute_req);
283 * Function: scsi_init_cmd_errh()
285 * Purpose: Initialize cmd fields related to error handling.
287 * Arguments: cmd - command that is ready to be queued.
289 * Notes: This function has the job of initializing a number of
290 * fields related to error handling. Typically this will
291 * be called once for each command, as required.
293 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
295 cmd->serial_number = 0;
296 scsi_set_resid(cmd, 0);
297 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
298 if (cmd->cmd_len == 0)
299 cmd->cmd_len = scsi_command_size(cmd->cmnd);
302 void scsi_device_unbusy(struct scsi_device *sdev)
304 struct Scsi_Host *shost = sdev->host;
305 struct scsi_target *starget = scsi_target(sdev);
306 unsigned long flags;
308 spin_lock_irqsave(shost->host_lock, flags);
309 shost->host_busy--;
310 starget->target_busy--;
311 if (unlikely(scsi_host_in_recovery(shost) &&
312 (shost->host_failed || shost->host_eh_scheduled)))
313 scsi_eh_wakeup(shost);
314 spin_unlock(shost->host_lock);
315 spin_lock(sdev->request_queue->queue_lock);
316 sdev->device_busy--;
317 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
321 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
322 * and call blk_run_queue for all the scsi_devices on the target -
323 * including current_sdev first.
325 * Called with *no* scsi locks held.
327 static void scsi_single_lun_run(struct scsi_device *current_sdev)
329 struct Scsi_Host *shost = current_sdev->host;
330 struct scsi_device *sdev, *tmp;
331 struct scsi_target *starget = scsi_target(current_sdev);
332 unsigned long flags;
334 spin_lock_irqsave(shost->host_lock, flags);
335 starget->starget_sdev_user = NULL;
336 spin_unlock_irqrestore(shost->host_lock, flags);
339 * Call blk_run_queue for all LUNs on the target, starting with
340 * current_sdev. We race with others (to set starget_sdev_user),
341 * but in most cases, we will be first. Ideally, each LU on the
342 * target would get some limited time or requests on the target.
344 blk_run_queue(current_sdev->request_queue);
346 spin_lock_irqsave(shost->host_lock, flags);
347 if (starget->starget_sdev_user)
348 goto out;
349 list_for_each_entry_safe(sdev, tmp, &starget->devices,
350 same_target_siblings) {
351 if (sdev == current_sdev)
352 continue;
353 if (scsi_device_get(sdev))
354 continue;
356 spin_unlock_irqrestore(shost->host_lock, flags);
357 blk_run_queue(sdev->request_queue);
358 spin_lock_irqsave(shost->host_lock, flags);
360 scsi_device_put(sdev);
362 out:
363 spin_unlock_irqrestore(shost->host_lock, flags);
366 static inline int scsi_device_is_busy(struct scsi_device *sdev)
368 if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
369 return 1;
371 return 0;
374 static inline int scsi_target_is_busy(struct scsi_target *starget)
376 return ((starget->can_queue > 0 &&
377 starget->target_busy >= starget->can_queue) ||
378 starget->target_blocked);
381 static inline int scsi_host_is_busy(struct Scsi_Host *shost)
383 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
384 shost->host_blocked || shost->host_self_blocked)
385 return 1;
387 return 0;
391 * Function: scsi_run_queue()
393 * Purpose: Select a proper request queue to serve next
395 * Arguments: q - last request's queue
397 * Returns: Nothing
399 * Notes: The previous command was completely finished, start
400 * a new one if possible.
402 static void scsi_run_queue(struct request_queue *q)
404 struct scsi_device *sdev = q->queuedata;
405 struct Scsi_Host *shost;
406 LIST_HEAD(starved_list);
407 unsigned long flags;
409 /* if the device is dead, sdev will be NULL, so no queue to run */
410 if (!sdev)
411 return;
413 shost = sdev->host;
414 if (scsi_target(sdev)->single_lun)
415 scsi_single_lun_run(sdev);
417 spin_lock_irqsave(shost->host_lock, flags);
418 list_splice_init(&shost->starved_list, &starved_list);
420 while (!list_empty(&starved_list)) {
422 * As long as shost is accepting commands and we have
423 * starved queues, call blk_run_queue. scsi_request_fn
424 * drops the queue_lock and can add us back to the
425 * starved_list.
427 * host_lock protects the starved_list and starved_entry.
428 * scsi_request_fn must get the host_lock before checking
429 * or modifying starved_list or starved_entry.
431 if (scsi_host_is_busy(shost))
432 break;
434 sdev = list_entry(starved_list.next,
435 struct scsi_device, starved_entry);
436 list_del_init(&sdev->starved_entry);
437 if (scsi_target_is_busy(scsi_target(sdev))) {
438 list_move_tail(&sdev->starved_entry,
439 &shost->starved_list);
440 continue;
443 spin_unlock(shost->host_lock);
444 spin_lock(sdev->request_queue->queue_lock);
445 __blk_run_queue(sdev->request_queue);
446 spin_unlock(sdev->request_queue->queue_lock);
447 spin_lock(shost->host_lock);
449 /* put any unprocessed entries back */
450 list_splice(&starved_list, &shost->starved_list);
451 spin_unlock_irqrestore(shost->host_lock, flags);
453 blk_run_queue(q);
456 void scsi_requeue_run_queue(struct work_struct *work)
458 struct scsi_device *sdev;
459 struct request_queue *q;
461 sdev = container_of(work, struct scsi_device, requeue_work);
462 q = sdev->request_queue;
463 scsi_run_queue(q);
467 * Function: scsi_requeue_command()
469 * Purpose: Handle post-processing of completed commands.
471 * Arguments: q - queue to operate on
472 * cmd - command that may need to be requeued.
474 * Returns: Nothing
476 * Notes: After command completion, there may be blocks left
477 * over which weren't finished by the previous command
478 * this can be for a number of reasons - the main one is
479 * I/O errors in the middle of the request, in which case
480 * we need to request the blocks that come after the bad
481 * sector.
482 * Notes: Upon return, cmd is a stale pointer.
484 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
486 struct request *req = cmd->request;
487 unsigned long flags;
489 spin_lock_irqsave(q->queue_lock, flags);
490 scsi_unprep_request(req);
491 blk_requeue_request(q, req);
492 spin_unlock_irqrestore(q->queue_lock, flags);
494 scsi_run_queue(q);
497 void scsi_next_command(struct scsi_cmnd *cmd)
499 struct scsi_device *sdev = cmd->device;
500 struct request_queue *q = sdev->request_queue;
502 /* need to hold a reference on the device before we let go of the cmd */
503 get_device(&sdev->sdev_gendev);
505 scsi_put_command(cmd);
506 scsi_run_queue(q);
508 /* ok to remove device now */
509 put_device(&sdev->sdev_gendev);
512 void scsi_run_host_queues(struct Scsi_Host *shost)
514 struct scsi_device *sdev;
516 shost_for_each_device(sdev, shost)
517 scsi_run_queue(sdev->request_queue);
520 static void __scsi_release_buffers(struct scsi_cmnd *, int);
523 * Function: scsi_end_request()
525 * Purpose: Post-processing of completed commands (usually invoked at end
526 * of upper level post-processing and scsi_io_completion).
528 * Arguments: cmd - command that is complete.
529 * error - 0 if I/O indicates success, < 0 for I/O error.
530 * bytes - number of bytes of completed I/O
531 * requeue - indicates whether we should requeue leftovers.
533 * Lock status: Assumed that lock is not held upon entry.
535 * Returns: cmd if requeue required, NULL otherwise.
537 * Notes: This is called for block device requests in order to
538 * mark some number of sectors as complete.
540 * We are guaranteeing that the request queue will be goosed
541 * at some point during this call.
542 * Notes: If cmd was requeued, upon return it will be a stale pointer.
544 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
545 int bytes, int requeue)
547 struct request_queue *q = cmd->device->request_queue;
548 struct request *req = cmd->request;
551 * If there are blocks left over at the end, set up the command
552 * to queue the remainder of them.
554 if (blk_end_request(req, error, bytes)) {
555 /* kill remainder if no retrys */
556 if (error && scsi_noretry_cmd(cmd))
557 blk_end_request_all(req, error);
558 else {
559 if (requeue) {
561 * Bleah. Leftovers again. Stick the
562 * leftovers in the front of the
563 * queue, and goose the queue again.
565 scsi_release_buffers(cmd);
566 scsi_requeue_command(q, cmd);
567 cmd = NULL;
569 return cmd;
574 * This will goose the queue request function at the end, so we don't
575 * need to worry about launching another command.
577 __scsi_release_buffers(cmd, 0);
578 scsi_next_command(cmd);
579 return NULL;
582 static inline unsigned int scsi_sgtable_index(unsigned short nents)
584 unsigned int index;
586 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
588 if (nents <= 8)
589 index = 0;
590 else
591 index = get_count_order(nents) - 3;
593 return index;
596 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
598 struct scsi_host_sg_pool *sgp;
600 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
601 mempool_free(sgl, sgp->pool);
604 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
606 struct scsi_host_sg_pool *sgp;
608 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
609 return mempool_alloc(sgp->pool, gfp_mask);
612 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
613 gfp_t gfp_mask)
615 int ret;
617 BUG_ON(!nents);
619 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
620 gfp_mask, scsi_sg_alloc);
621 if (unlikely(ret))
622 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
623 scsi_sg_free);
625 return ret;
628 static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
630 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
633 static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
636 if (cmd->sdb.table.nents)
637 scsi_free_sgtable(&cmd->sdb);
639 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
641 if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
642 struct scsi_data_buffer *bidi_sdb =
643 cmd->request->next_rq->special;
644 scsi_free_sgtable(bidi_sdb);
645 kmem_cache_free(scsi_sdb_cache, bidi_sdb);
646 cmd->request->next_rq->special = NULL;
649 if (scsi_prot_sg_count(cmd))
650 scsi_free_sgtable(cmd->prot_sdb);
654 * Function: scsi_release_buffers()
656 * Purpose: Completion processing for block device I/O requests.
658 * Arguments: cmd - command that we are bailing.
660 * Lock status: Assumed that no lock is held upon entry.
662 * Returns: Nothing
664 * Notes: In the event that an upper level driver rejects a
665 * command, we must release resources allocated during
666 * the __init_io() function. Primarily this would involve
667 * the scatter-gather table, and potentially any bounce
668 * buffers.
670 void scsi_release_buffers(struct scsi_cmnd *cmd)
672 __scsi_release_buffers(cmd, 1);
674 EXPORT_SYMBOL(scsi_release_buffers);
676 static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
678 int error = 0;
680 switch(host_byte(result)) {
681 case DID_TRANSPORT_FAILFAST:
682 error = -ENOLINK;
683 break;
684 case DID_TARGET_FAILURE:
685 cmd->result |= (DID_OK << 16);
686 error = -EREMOTEIO;
687 break;
688 case DID_NEXUS_FAILURE:
689 cmd->result |= (DID_OK << 16);
690 error = -EBADE;
691 break;
692 default:
693 error = -EIO;
694 break;
697 return error;
701 * Function: scsi_io_completion()
703 * Purpose: Completion processing for block device I/O requests.
705 * Arguments: cmd - command that is finished.
707 * Lock status: Assumed that no lock is held upon entry.
709 * Returns: Nothing
711 * Notes: This function is matched in terms of capabilities to
712 * the function that created the scatter-gather list.
713 * In other words, if there are no bounce buffers
714 * (the normal case for most drivers), we don't need
715 * the logic to deal with cleaning up afterwards.
717 * We must call scsi_end_request(). This will finish off
718 * the specified number of sectors. If we are done, the
719 * command block will be released and the queue function
720 * will be goosed. If we are not done then we have to
721 * figure out what to do next:
723 * a) We can call scsi_requeue_command(). The request
724 * will be unprepared and put back on the queue. Then
725 * a new command will be created for it. This should
726 * be used if we made forward progress, or if we want
727 * to switch from READ(10) to READ(6) for example.
729 * b) We can call scsi_queue_insert(). The request will
730 * be put back on the queue and retried using the same
731 * command as before, possibly after a delay.
733 * c) We can call blk_end_request() with -EIO to fail
734 * the remainder of the request.
736 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
738 int result = cmd->result;
739 struct request_queue *q = cmd->device->request_queue;
740 struct request *req = cmd->request;
741 int error = 0;
742 struct scsi_sense_hdr sshdr;
743 int sense_valid = 0;
744 int sense_deferred = 0;
745 enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
746 ACTION_DELAYED_RETRY} action;
747 char *description = NULL;
749 if (result) {
750 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
751 if (sense_valid)
752 sense_deferred = scsi_sense_is_deferred(&sshdr);
755 if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
756 req->errors = result;
757 if (result) {
758 if (sense_valid && req->sense) {
760 * SG_IO wants current and deferred errors
762 int len = 8 + cmd->sense_buffer[7];
764 if (len > SCSI_SENSE_BUFFERSIZE)
765 len = SCSI_SENSE_BUFFERSIZE;
766 memcpy(req->sense, cmd->sense_buffer, len);
767 req->sense_len = len;
769 if (!sense_deferred)
770 error = __scsi_error_from_host_byte(cmd, result);
773 req->resid_len = scsi_get_resid(cmd);
775 if (scsi_bidi_cmnd(cmd)) {
777 * Bidi commands Must be complete as a whole,
778 * both sides at once.
780 req->next_rq->resid_len = scsi_in(cmd)->resid;
782 scsi_release_buffers(cmd);
783 blk_end_request_all(req, 0);
785 scsi_next_command(cmd);
786 return;
790 /* no bidi support for !REQ_TYPE_BLOCK_PC yet */
791 BUG_ON(blk_bidi_rq(req));
794 * Next deal with any sectors which we were able to correctly
795 * handle.
797 SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, "
798 "%d bytes done.\n",
799 blk_rq_sectors(req), good_bytes));
802 * Recovered errors need reporting, but they're always treated
803 * as success, so fiddle the result code here. For BLOCK_PC
804 * we already took a copy of the original into rq->errors which
805 * is what gets returned to the user
807 if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
808 /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
809 * print since caller wants ATA registers. Only occurs on
810 * SCSI ATA PASS_THROUGH commands when CK_COND=1
812 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
814 else if (!(req->cmd_flags & REQ_QUIET))
815 scsi_print_sense("", cmd);
816 result = 0;
817 /* BLOCK_PC may have set error */
818 error = 0;
822 * A number of bytes were successfully read. If there
823 * are leftovers and there is some kind of error
824 * (result != 0), retry the rest.
826 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
827 return;
829 error = __scsi_error_from_host_byte(cmd, result);
831 if (host_byte(result) == DID_RESET) {
832 /* Third party bus reset or reset for error recovery
833 * reasons. Just retry the command and see what
834 * happens.
836 action = ACTION_RETRY;
837 } else if (sense_valid && !sense_deferred) {
838 switch (sshdr.sense_key) {
839 case UNIT_ATTENTION:
840 if (cmd->device->removable) {
841 /* Detected disc change. Set a bit
842 * and quietly refuse further access.
844 cmd->device->changed = 1;
845 description = "Media Changed";
846 action = ACTION_FAIL;
847 } else {
848 /* Must have been a power glitch, or a
849 * bus reset. Could not have been a
850 * media change, so we just retry the
851 * command and see what happens.
853 action = ACTION_RETRY;
855 break;
856 case ILLEGAL_REQUEST:
857 /* If we had an ILLEGAL REQUEST returned, then
858 * we may have performed an unsupported
859 * command. The only thing this should be
860 * would be a ten byte read where only a six
861 * byte read was supported. Also, on a system
862 * where READ CAPACITY failed, we may have
863 * read past the end of the disk.
865 if ((cmd->device->use_10_for_rw &&
866 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
867 (cmd->cmnd[0] == READ_10 ||
868 cmd->cmnd[0] == WRITE_10)) {
869 /* This will issue a new 6-byte command. */
870 cmd->device->use_10_for_rw = 0;
871 action = ACTION_REPREP;
872 } else if (sshdr.asc == 0x10) /* DIX */ {
873 description = "Host Data Integrity Failure";
874 action = ACTION_FAIL;
875 error = -EILSEQ;
876 /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
877 } else if ((sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
878 (cmd->cmnd[0] == UNMAP ||
879 cmd->cmnd[0] == WRITE_SAME_16 ||
880 cmd->cmnd[0] == WRITE_SAME)) {
881 description = "Discard failure";
882 action = ACTION_FAIL;
883 } else
884 action = ACTION_FAIL;
885 break;
886 case ABORTED_COMMAND:
887 action = ACTION_FAIL;
888 if (sshdr.asc == 0x10) { /* DIF */
889 description = "Target Data Integrity Failure";
890 error = -EILSEQ;
892 break;
893 case NOT_READY:
894 /* If the device is in the process of becoming
895 * ready, or has a temporary blockage, retry.
897 if (sshdr.asc == 0x04) {
898 switch (sshdr.ascq) {
899 case 0x01: /* becoming ready */
900 case 0x04: /* format in progress */
901 case 0x05: /* rebuild in progress */
902 case 0x06: /* recalculation in progress */
903 case 0x07: /* operation in progress */
904 case 0x08: /* Long write in progress */
905 case 0x09: /* self test in progress */
906 case 0x14: /* space allocation in progress */
907 action = ACTION_DELAYED_RETRY;
908 break;
909 default:
910 description = "Device not ready";
911 action = ACTION_FAIL;
912 break;
914 } else {
915 description = "Device not ready";
916 action = ACTION_FAIL;
918 break;
919 case VOLUME_OVERFLOW:
920 /* See SSC3rXX or current. */
921 action = ACTION_FAIL;
922 break;
923 default:
924 description = "Unhandled sense code";
925 action = ACTION_FAIL;
926 break;
928 } else {
929 description = "Unhandled error code";
930 action = ACTION_FAIL;
933 switch (action) {
934 case ACTION_FAIL:
935 /* Give up and fail the remainder of the request */
936 scsi_release_buffers(cmd);
937 if (!(req->cmd_flags & REQ_QUIET)) {
938 if (description)
939 scmd_printk(KERN_INFO, cmd, "%s\n",
940 description);
941 scsi_print_result(cmd);
942 if (driver_byte(result) & DRIVER_SENSE)
943 scsi_print_sense("", cmd);
944 scsi_print_command(cmd);
946 if (blk_end_request_err(req, error))
947 scsi_requeue_command(q, cmd);
948 else
949 scsi_next_command(cmd);
950 break;
951 case ACTION_REPREP:
952 /* Unprep the request and put it back at the head of the queue.
953 * A new command will be prepared and issued.
955 scsi_release_buffers(cmd);
956 scsi_requeue_command(q, cmd);
957 break;
958 case ACTION_RETRY:
959 /* Retry the same command immediately */
960 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
961 break;
962 case ACTION_DELAYED_RETRY:
963 /* Retry the same command after a delay */
964 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
965 break;
969 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
970 gfp_t gfp_mask)
972 int count;
975 * If sg table allocation fails, requeue request later.
977 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
978 gfp_mask))) {
979 return BLKPREP_DEFER;
982 req->buffer = NULL;
985 * Next, walk the list, and fill in the addresses and sizes of
986 * each segment.
988 count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
989 BUG_ON(count > sdb->table.nents);
990 sdb->table.nents = count;
991 sdb->length = blk_rq_bytes(req);
992 return BLKPREP_OK;
996 * Function: scsi_init_io()
998 * Purpose: SCSI I/O initialize function.
1000 * Arguments: cmd - Command descriptor we wish to initialize
1002 * Returns: 0 on success
1003 * BLKPREP_DEFER if the failure is retryable
1004 * BLKPREP_KILL if the failure is fatal
1006 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1008 struct request *rq = cmd->request;
1010 int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask);
1011 if (error)
1012 goto err_exit;
1014 if (blk_bidi_rq(rq)) {
1015 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1016 scsi_sdb_cache, GFP_ATOMIC);
1017 if (!bidi_sdb) {
1018 error = BLKPREP_DEFER;
1019 goto err_exit;
1022 rq->next_rq->special = bidi_sdb;
1023 error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC);
1024 if (error)
1025 goto err_exit;
1028 if (blk_integrity_rq(rq)) {
1029 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1030 int ivecs, count;
1032 BUG_ON(prot_sdb == NULL);
1033 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1035 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1036 error = BLKPREP_DEFER;
1037 goto err_exit;
1040 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1041 prot_sdb->table.sgl);
1042 BUG_ON(unlikely(count > ivecs));
1043 BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1045 cmd->prot_sdb = prot_sdb;
1046 cmd->prot_sdb->table.nents = count;
1049 return BLKPREP_OK ;
1051 err_exit:
1052 scsi_release_buffers(cmd);
1053 cmd->request->special = NULL;
1054 scsi_put_command(cmd);
1055 return error;
1057 EXPORT_SYMBOL(scsi_init_io);
1059 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1060 struct request *req)
1062 struct scsi_cmnd *cmd;
1064 if (!req->special) {
1065 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1066 if (unlikely(!cmd))
1067 return NULL;
1068 req->special = cmd;
1069 } else {
1070 cmd = req->special;
1073 /* pull a tag out of the request if we have one */
1074 cmd->tag = req->tag;
1075 cmd->request = req;
1077 cmd->cmnd = req->cmd;
1078 cmd->prot_op = SCSI_PROT_NORMAL;
1080 return cmd;
1083 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1085 struct scsi_cmnd *cmd;
1086 int ret = scsi_prep_state_check(sdev, req);
1088 if (ret != BLKPREP_OK)
1089 return ret;
1091 cmd = scsi_get_cmd_from_req(sdev, req);
1092 if (unlikely(!cmd))
1093 return BLKPREP_DEFER;
1096 * BLOCK_PC requests may transfer data, in which case they must
1097 * a bio attached to them. Or they might contain a SCSI command
1098 * that does not transfer data, in which case they may optionally
1099 * submit a request without an attached bio.
1101 if (req->bio) {
1102 int ret;
1104 BUG_ON(!req->nr_phys_segments);
1106 ret = scsi_init_io(cmd, GFP_ATOMIC);
1107 if (unlikely(ret))
1108 return ret;
1109 } else {
1110 BUG_ON(blk_rq_bytes(req));
1112 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1113 req->buffer = NULL;
1116 cmd->cmd_len = req->cmd_len;
1117 if (!blk_rq_bytes(req))
1118 cmd->sc_data_direction = DMA_NONE;
1119 else if (rq_data_dir(req) == WRITE)
1120 cmd->sc_data_direction = DMA_TO_DEVICE;
1121 else
1122 cmd->sc_data_direction = DMA_FROM_DEVICE;
1124 cmd->transfersize = blk_rq_bytes(req);
1125 cmd->allowed = req->retries;
1126 return BLKPREP_OK;
1128 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1131 * Setup a REQ_TYPE_FS command. These are simple read/write request
1132 * from filesystems that still need to be translated to SCSI CDBs from
1133 * the ULD.
1135 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1137 struct scsi_cmnd *cmd;
1138 int ret = scsi_prep_state_check(sdev, req);
1140 if (ret != BLKPREP_OK)
1141 return ret;
1143 if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1144 && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1145 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1146 if (ret != BLKPREP_OK)
1147 return ret;
1151 * Filesystem requests must transfer data.
1153 BUG_ON(!req->nr_phys_segments);
1155 cmd = scsi_get_cmd_from_req(sdev, req);
1156 if (unlikely(!cmd))
1157 return BLKPREP_DEFER;
1159 memset(cmd->cmnd, 0, BLK_MAX_CDB);
1160 return scsi_init_io(cmd, GFP_ATOMIC);
1162 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1164 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1166 int ret = BLKPREP_OK;
1169 * If the device is not in running state we will reject some
1170 * or all commands.
1172 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1173 switch (sdev->sdev_state) {
1174 case SDEV_OFFLINE:
1176 * If the device is offline we refuse to process any
1177 * commands. The device must be brought online
1178 * before trying any recovery commands.
1180 sdev_printk(KERN_ERR, sdev,
1181 "rejecting I/O to offline device\n");
1182 ret = BLKPREP_KILL;
1183 break;
1184 case SDEV_DEL:
1186 * If the device is fully deleted, we refuse to
1187 * process any commands as well.
1189 sdev_printk(KERN_ERR, sdev,
1190 "rejecting I/O to dead device\n");
1191 ret = BLKPREP_KILL;
1192 break;
1193 case SDEV_QUIESCE:
1194 case SDEV_BLOCK:
1195 case SDEV_CREATED_BLOCK:
1197 * If the devices is blocked we defer normal commands.
1199 if (!(req->cmd_flags & REQ_PREEMPT))
1200 ret = BLKPREP_DEFER;
1201 break;
1202 default:
1204 * For any other not fully online state we only allow
1205 * special commands. In particular any user initiated
1206 * command is not allowed.
1208 if (!(req->cmd_flags & REQ_PREEMPT))
1209 ret = BLKPREP_KILL;
1210 break;
1213 return ret;
1215 EXPORT_SYMBOL(scsi_prep_state_check);
1217 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1219 struct scsi_device *sdev = q->queuedata;
1221 switch (ret) {
1222 case BLKPREP_KILL:
1223 req->errors = DID_NO_CONNECT << 16;
1224 /* release the command and kill it */
1225 if (req->special) {
1226 struct scsi_cmnd *cmd = req->special;
1227 scsi_release_buffers(cmd);
1228 scsi_put_command(cmd);
1229 req->special = NULL;
1231 break;
1232 case BLKPREP_DEFER:
1234 * If we defer, the blk_peek_request() returns NULL, but the
1235 * queue must be restarted, so we schedule a callback to happen
1236 * shortly.
1238 if (sdev->device_busy == 0)
1239 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1240 break;
1241 default:
1242 req->cmd_flags |= REQ_DONTPREP;
1245 return ret;
1247 EXPORT_SYMBOL(scsi_prep_return);
1249 int scsi_prep_fn(struct request_queue *q, struct request *req)
1251 struct scsi_device *sdev = q->queuedata;
1252 int ret = BLKPREP_KILL;
1254 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1255 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1256 return scsi_prep_return(q, req, ret);
1258 EXPORT_SYMBOL(scsi_prep_fn);
1261 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1262 * return 0.
1264 * Called with the queue_lock held.
1266 static inline int scsi_dev_queue_ready(struct request_queue *q,
1267 struct scsi_device *sdev)
1269 if (sdev->device_busy == 0 && sdev->device_blocked) {
1271 * unblock after device_blocked iterates to zero
1273 if (--sdev->device_blocked == 0) {
1274 SCSI_LOG_MLQUEUE(3,
1275 sdev_printk(KERN_INFO, sdev,
1276 "unblocking device at zero depth\n"));
1277 } else {
1278 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1279 return 0;
1282 if (scsi_device_is_busy(sdev))
1283 return 0;
1285 return 1;
1290 * scsi_target_queue_ready: checks if there we can send commands to target
1291 * @sdev: scsi device on starget to check.
1293 * Called with the host lock held.
1295 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1296 struct scsi_device *sdev)
1298 struct scsi_target *starget = scsi_target(sdev);
1300 if (starget->single_lun) {
1301 if (starget->starget_sdev_user &&
1302 starget->starget_sdev_user != sdev)
1303 return 0;
1304 starget->starget_sdev_user = sdev;
1307 if (starget->target_busy == 0 && starget->target_blocked) {
1309 * unblock after target_blocked iterates to zero
1311 if (--starget->target_blocked == 0) {
1312 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1313 "unblocking target at zero depth\n"));
1314 } else
1315 return 0;
1318 if (scsi_target_is_busy(starget)) {
1319 if (list_empty(&sdev->starved_entry))
1320 list_add_tail(&sdev->starved_entry,
1321 &shost->starved_list);
1322 return 0;
1325 /* We're OK to process the command, so we can't be starved */
1326 if (!list_empty(&sdev->starved_entry))
1327 list_del_init(&sdev->starved_entry);
1328 return 1;
1332 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1333 * return 0. We must end up running the queue again whenever 0 is
1334 * returned, else IO can hang.
1336 * Called with host_lock held.
1338 static inline int scsi_host_queue_ready(struct request_queue *q,
1339 struct Scsi_Host *shost,
1340 struct scsi_device *sdev)
1342 if (scsi_host_in_recovery(shost))
1343 return 0;
1344 if (shost->host_busy == 0 && shost->host_blocked) {
1346 * unblock after host_blocked iterates to zero
1348 if (--shost->host_blocked == 0) {
1349 SCSI_LOG_MLQUEUE(3,
1350 printk("scsi%d unblocking host at zero depth\n",
1351 shost->host_no));
1352 } else {
1353 return 0;
1356 if (scsi_host_is_busy(shost)) {
1357 if (list_empty(&sdev->starved_entry))
1358 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1359 return 0;
1362 /* We're OK to process the command, so we can't be starved */
1363 if (!list_empty(&sdev->starved_entry))
1364 list_del_init(&sdev->starved_entry);
1366 return 1;
1370 * Busy state exporting function for request stacking drivers.
1372 * For efficiency, no lock is taken to check the busy state of
1373 * shost/starget/sdev, since the returned value is not guaranteed and
1374 * may be changed after request stacking drivers call the function,
1375 * regardless of taking lock or not.
1377 * When scsi can't dispatch I/Os anymore and needs to kill I/Os
1378 * (e.g. !sdev), scsi needs to return 'not busy'.
1379 * Otherwise, request stacking drivers may hold requests forever.
1381 static int scsi_lld_busy(struct request_queue *q)
1383 struct scsi_device *sdev = q->queuedata;
1384 struct Scsi_Host *shost;
1385 struct scsi_target *starget;
1387 if (!sdev)
1388 return 0;
1390 shost = sdev->host;
1391 starget = scsi_target(sdev);
1393 if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
1394 scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
1395 return 1;
1397 return 0;
1401 * Kill a request for a dead device
1403 static void scsi_kill_request(struct request *req, struct request_queue *q)
1405 struct scsi_cmnd *cmd = req->special;
1406 struct scsi_device *sdev;
1407 struct scsi_target *starget;
1408 struct Scsi_Host *shost;
1410 blk_start_request(req);
1412 sdev = cmd->device;
1413 starget = scsi_target(sdev);
1414 shost = sdev->host;
1415 scsi_init_cmd_errh(cmd);
1416 cmd->result = DID_NO_CONNECT << 16;
1417 atomic_inc(&cmd->device->iorequest_cnt);
1420 * SCSI request completion path will do scsi_device_unbusy(),
1421 * bump busy counts. To bump the counters, we need to dance
1422 * with the locks as normal issue path does.
1424 sdev->device_busy++;
1425 spin_unlock(sdev->request_queue->queue_lock);
1426 spin_lock(shost->host_lock);
1427 shost->host_busy++;
1428 starget->target_busy++;
1429 spin_unlock(shost->host_lock);
1430 spin_lock(sdev->request_queue->queue_lock);
1432 blk_complete_request(req);
1435 static void scsi_softirq_done(struct request *rq)
1437 struct scsi_cmnd *cmd = rq->special;
1438 unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1439 int disposition;
1441 INIT_LIST_HEAD(&cmd->eh_entry);
1443 atomic_inc(&cmd->device->iodone_cnt);
1444 if (cmd->result)
1445 atomic_inc(&cmd->device->ioerr_cnt);
1447 disposition = scsi_decide_disposition(cmd);
1448 if (disposition != SUCCESS &&
1449 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1450 sdev_printk(KERN_ERR, cmd->device,
1451 "timing out command, waited %lus\n",
1452 wait_for/HZ);
1453 disposition = SUCCESS;
1456 scsi_log_completion(cmd, disposition);
1458 switch (disposition) {
1459 case SUCCESS:
1460 scsi_finish_command(cmd);
1461 break;
1462 case NEEDS_RETRY:
1463 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1464 break;
1465 case ADD_TO_MLQUEUE:
1466 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1467 break;
1468 default:
1469 if (!scsi_eh_scmd_add(cmd, 0))
1470 scsi_finish_command(cmd);
1475 * Function: scsi_request_fn()
1477 * Purpose: Main strategy routine for SCSI.
1479 * Arguments: q - Pointer to actual queue.
1481 * Returns: Nothing
1483 * Lock status: IO request lock assumed to be held when called.
1485 static void scsi_request_fn(struct request_queue *q)
1487 struct scsi_device *sdev = q->queuedata;
1488 struct Scsi_Host *shost;
1489 struct scsi_cmnd *cmd;
1490 struct request *req;
1492 if (!sdev) {
1493 printk("scsi: killing requests for dead queue\n");
1494 while ((req = blk_peek_request(q)) != NULL)
1495 scsi_kill_request(req, q);
1496 return;
1499 if(!get_device(&sdev->sdev_gendev))
1500 /* We must be tearing the block queue down already */
1501 return;
1504 * To start with, we keep looping until the queue is empty, or until
1505 * the host is no longer able to accept any more requests.
1507 shost = sdev->host;
1508 for (;;) {
1509 int rtn;
1511 * get next queueable request. We do this early to make sure
1512 * that the request is fully prepared even if we cannot
1513 * accept it.
1515 req = blk_peek_request(q);
1516 if (!req || !scsi_dev_queue_ready(q, sdev))
1517 break;
1519 if (unlikely(!scsi_device_online(sdev))) {
1520 sdev_printk(KERN_ERR, sdev,
1521 "rejecting I/O to offline device\n");
1522 scsi_kill_request(req, q);
1523 continue;
1528 * Remove the request from the request list.
1530 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1531 blk_start_request(req);
1532 sdev->device_busy++;
1534 spin_unlock(q->queue_lock);
1535 cmd = req->special;
1536 if (unlikely(cmd == NULL)) {
1537 printk(KERN_CRIT "impossible request in %s.\n"
1538 "please mail a stack trace to "
1539 "linux-scsi@vger.kernel.org\n",
1540 __func__);
1541 blk_dump_rq_flags(req, "foo");
1542 BUG();
1544 spin_lock(shost->host_lock);
1547 * We hit this when the driver is using a host wide
1548 * tag map. For device level tag maps the queue_depth check
1549 * in the device ready fn would prevent us from trying
1550 * to allocate a tag. Since the map is a shared host resource
1551 * we add the dev to the starved list so it eventually gets
1552 * a run when a tag is freed.
1554 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1555 if (list_empty(&sdev->starved_entry))
1556 list_add_tail(&sdev->starved_entry,
1557 &shost->starved_list);
1558 goto not_ready;
1561 if (!scsi_target_queue_ready(shost, sdev))
1562 goto not_ready;
1564 if (!scsi_host_queue_ready(q, shost, sdev))
1565 goto not_ready;
1567 scsi_target(sdev)->target_busy++;
1568 shost->host_busy++;
1571 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1572 * take the lock again.
1574 spin_unlock_irq(shost->host_lock);
1577 * Finally, initialize any error handling parameters, and set up
1578 * the timers for timeouts.
1580 scsi_init_cmd_errh(cmd);
1583 * Dispatch the command to the low-level driver.
1585 rtn = scsi_dispatch_cmd(cmd);
1586 spin_lock_irq(q->queue_lock);
1587 if (rtn)
1588 goto out_delay;
1591 goto out;
1593 not_ready:
1594 spin_unlock_irq(shost->host_lock);
1597 * lock q, handle tag, requeue req, and decrement device_busy. We
1598 * must return with queue_lock held.
1600 * Decrementing device_busy without checking it is OK, as all such
1601 * cases (host limits or settings) should run the queue at some
1602 * later time.
1604 spin_lock_irq(q->queue_lock);
1605 blk_requeue_request(q, req);
1606 sdev->device_busy--;
1607 out_delay:
1608 if (sdev->device_busy == 0)
1609 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1610 out:
1611 /* must be careful here...if we trigger the ->remove() function
1612 * we cannot be holding the q lock */
1613 spin_unlock_irq(q->queue_lock);
1614 put_device(&sdev->sdev_gendev);
1615 spin_lock_irq(q->queue_lock);
1618 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1620 struct device *host_dev;
1621 u64 bounce_limit = 0xffffffff;
1623 if (shost->unchecked_isa_dma)
1624 return BLK_BOUNCE_ISA;
1626 * Platforms with virtual-DMA translation
1627 * hardware have no practical limit.
1629 if (!PCI_DMA_BUS_IS_PHYS)
1630 return BLK_BOUNCE_ANY;
1632 host_dev = scsi_get_device(shost);
1633 if (host_dev && host_dev->dma_mask)
1634 bounce_limit = *host_dev->dma_mask;
1636 return bounce_limit;
1638 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1640 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1641 request_fn_proc *request_fn)
1643 struct request_queue *q;
1644 struct device *dev = shost->shost_gendev.parent;
1646 q = blk_init_queue(request_fn, NULL);
1647 if (!q)
1648 return NULL;
1651 * this limit is imposed by hardware restrictions
1653 blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1654 SCSI_MAX_SG_CHAIN_SEGMENTS));
1656 if (scsi_host_prot_dma(shost)) {
1657 shost->sg_prot_tablesize =
1658 min_not_zero(shost->sg_prot_tablesize,
1659 (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1660 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1661 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1664 blk_queue_max_hw_sectors(q, shost->max_sectors);
1665 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1666 blk_queue_segment_boundary(q, shost->dma_boundary);
1667 dma_set_seg_boundary(dev, shost->dma_boundary);
1669 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1671 if (!shost->use_clustering)
1672 q->limits.cluster = 0;
1675 * set a reasonable default alignment on word boundaries: the
1676 * host and device may alter it using
1677 * blk_queue_update_dma_alignment() later.
1679 blk_queue_dma_alignment(q, 0x03);
1681 return q;
1683 EXPORT_SYMBOL(__scsi_alloc_queue);
1685 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1687 struct request_queue *q;
1689 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1690 if (!q)
1691 return NULL;
1693 blk_queue_prep_rq(q, scsi_prep_fn);
1694 blk_queue_softirq_done(q, scsi_softirq_done);
1695 blk_queue_rq_timed_out(q, scsi_times_out);
1696 blk_queue_lld_busy(q, scsi_lld_busy);
1697 return q;
1700 void scsi_free_queue(struct request_queue *q)
1702 unsigned long flags;
1704 WARN_ON(q->queuedata);
1706 /* cause scsi_request_fn() to kill all non-finished requests */
1707 spin_lock_irqsave(q->queue_lock, flags);
1708 q->request_fn(q);
1709 spin_unlock_irqrestore(q->queue_lock, flags);
1711 blk_cleanup_queue(q);
1715 * Function: scsi_block_requests()
1717 * Purpose: Utility function used by low-level drivers to prevent further
1718 * commands from being queued to the device.
1720 * Arguments: shost - Host in question
1722 * Returns: Nothing
1724 * Lock status: No locks are assumed held.
1726 * Notes: There is no timer nor any other means by which the requests
1727 * get unblocked other than the low-level driver calling
1728 * scsi_unblock_requests().
1730 void scsi_block_requests(struct Scsi_Host *shost)
1732 shost->host_self_blocked = 1;
1734 EXPORT_SYMBOL(scsi_block_requests);
1737 * Function: scsi_unblock_requests()
1739 * Purpose: Utility function used by low-level drivers to allow further
1740 * commands from being queued to the device.
1742 * Arguments: shost - Host in question
1744 * Returns: Nothing
1746 * Lock status: No locks are assumed held.
1748 * Notes: There is no timer nor any other means by which the requests
1749 * get unblocked other than the low-level driver calling
1750 * scsi_unblock_requests().
1752 * This is done as an API function so that changes to the
1753 * internals of the scsi mid-layer won't require wholesale
1754 * changes to drivers that use this feature.
1756 void scsi_unblock_requests(struct Scsi_Host *shost)
1758 shost->host_self_blocked = 0;
1759 scsi_run_host_queues(shost);
1761 EXPORT_SYMBOL(scsi_unblock_requests);
1763 int __init scsi_init_queue(void)
1765 int i;
1767 scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1768 sizeof(struct scsi_data_buffer),
1769 0, 0, NULL);
1770 if (!scsi_sdb_cache) {
1771 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1772 return -ENOMEM;
1775 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1776 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1777 int size = sgp->size * sizeof(struct scatterlist);
1779 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1780 SLAB_HWCACHE_ALIGN, NULL);
1781 if (!sgp->slab) {
1782 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1783 sgp->name);
1784 goto cleanup_sdb;
1787 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1788 sgp->slab);
1789 if (!sgp->pool) {
1790 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1791 sgp->name);
1792 goto cleanup_sdb;
1796 return 0;
1798 cleanup_sdb:
1799 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1800 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1801 if (sgp->pool)
1802 mempool_destroy(sgp->pool);
1803 if (sgp->slab)
1804 kmem_cache_destroy(sgp->slab);
1806 kmem_cache_destroy(scsi_sdb_cache);
1808 return -ENOMEM;
1811 void scsi_exit_queue(void)
1813 int i;
1815 kmem_cache_destroy(scsi_sdb_cache);
1817 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1818 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1819 mempool_destroy(sgp->pool);
1820 kmem_cache_destroy(sgp->slab);
1825 * scsi_mode_select - issue a mode select
1826 * @sdev: SCSI device to be queried
1827 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1828 * @sp: Save page bit (0 == don't save, 1 == save)
1829 * @modepage: mode page being requested
1830 * @buffer: request buffer (may not be smaller than eight bytes)
1831 * @len: length of request buffer.
1832 * @timeout: command timeout
1833 * @retries: number of retries before failing
1834 * @data: returns a structure abstracting the mode header data
1835 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1836 * must be SCSI_SENSE_BUFFERSIZE big.
1838 * Returns zero if successful; negative error number or scsi
1839 * status on error
1843 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1844 unsigned char *buffer, int len, int timeout, int retries,
1845 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1847 unsigned char cmd[10];
1848 unsigned char *real_buffer;
1849 int ret;
1851 memset(cmd, 0, sizeof(cmd));
1852 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1854 if (sdev->use_10_for_ms) {
1855 if (len > 65535)
1856 return -EINVAL;
1857 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1858 if (!real_buffer)
1859 return -ENOMEM;
1860 memcpy(real_buffer + 8, buffer, len);
1861 len += 8;
1862 real_buffer[0] = 0;
1863 real_buffer[1] = 0;
1864 real_buffer[2] = data->medium_type;
1865 real_buffer[3] = data->device_specific;
1866 real_buffer[4] = data->longlba ? 0x01 : 0;
1867 real_buffer[5] = 0;
1868 real_buffer[6] = data->block_descriptor_length >> 8;
1869 real_buffer[7] = data->block_descriptor_length;
1871 cmd[0] = MODE_SELECT_10;
1872 cmd[7] = len >> 8;
1873 cmd[8] = len;
1874 } else {
1875 if (len > 255 || data->block_descriptor_length > 255 ||
1876 data->longlba)
1877 return -EINVAL;
1879 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1880 if (!real_buffer)
1881 return -ENOMEM;
1882 memcpy(real_buffer + 4, buffer, len);
1883 len += 4;
1884 real_buffer[0] = 0;
1885 real_buffer[1] = data->medium_type;
1886 real_buffer[2] = data->device_specific;
1887 real_buffer[3] = data->block_descriptor_length;
1890 cmd[0] = MODE_SELECT;
1891 cmd[4] = len;
1894 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1895 sshdr, timeout, retries, NULL);
1896 kfree(real_buffer);
1897 return ret;
1899 EXPORT_SYMBOL_GPL(scsi_mode_select);
1902 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1903 * @sdev: SCSI device to be queried
1904 * @dbd: set if mode sense will allow block descriptors to be returned
1905 * @modepage: mode page being requested
1906 * @buffer: request buffer (may not be smaller than eight bytes)
1907 * @len: length of request buffer.
1908 * @timeout: command timeout
1909 * @retries: number of retries before failing
1910 * @data: returns a structure abstracting the mode header data
1911 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1912 * must be SCSI_SENSE_BUFFERSIZE big.
1914 * Returns zero if unsuccessful, or the header offset (either 4
1915 * or 8 depending on whether a six or ten byte command was
1916 * issued) if successful.
1919 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1920 unsigned char *buffer, int len, int timeout, int retries,
1921 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1923 unsigned char cmd[12];
1924 int use_10_for_ms;
1925 int header_length;
1926 int result;
1927 struct scsi_sense_hdr my_sshdr;
1929 memset(data, 0, sizeof(*data));
1930 memset(&cmd[0], 0, 12);
1931 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1932 cmd[2] = modepage;
1934 /* caller might not be interested in sense, but we need it */
1935 if (!sshdr)
1936 sshdr = &my_sshdr;
1938 retry:
1939 use_10_for_ms = sdev->use_10_for_ms;
1941 if (use_10_for_ms) {
1942 if (len < 8)
1943 len = 8;
1945 cmd[0] = MODE_SENSE_10;
1946 cmd[8] = len;
1947 header_length = 8;
1948 } else {
1949 if (len < 4)
1950 len = 4;
1952 cmd[0] = MODE_SENSE;
1953 cmd[4] = len;
1954 header_length = 4;
1957 memset(buffer, 0, len);
1959 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1960 sshdr, timeout, retries, NULL);
1962 /* This code looks awful: what it's doing is making sure an
1963 * ILLEGAL REQUEST sense return identifies the actual command
1964 * byte as the problem. MODE_SENSE commands can return
1965 * ILLEGAL REQUEST if the code page isn't supported */
1967 if (use_10_for_ms && !scsi_status_is_good(result) &&
1968 (driver_byte(result) & DRIVER_SENSE)) {
1969 if (scsi_sense_valid(sshdr)) {
1970 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1971 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1973 * Invalid command operation code
1975 sdev->use_10_for_ms = 0;
1976 goto retry;
1981 if(scsi_status_is_good(result)) {
1982 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1983 (modepage == 6 || modepage == 8))) {
1984 /* Initio breakage? */
1985 header_length = 0;
1986 data->length = 13;
1987 data->medium_type = 0;
1988 data->device_specific = 0;
1989 data->longlba = 0;
1990 data->block_descriptor_length = 0;
1991 } else if(use_10_for_ms) {
1992 data->length = buffer[0]*256 + buffer[1] + 2;
1993 data->medium_type = buffer[2];
1994 data->device_specific = buffer[3];
1995 data->longlba = buffer[4] & 0x01;
1996 data->block_descriptor_length = buffer[6]*256
1997 + buffer[7];
1998 } else {
1999 data->length = buffer[0] + 1;
2000 data->medium_type = buffer[1];
2001 data->device_specific = buffer[2];
2002 data->block_descriptor_length = buffer[3];
2004 data->header_length = header_length;
2007 return result;
2009 EXPORT_SYMBOL(scsi_mode_sense);
2012 * scsi_test_unit_ready - test if unit is ready
2013 * @sdev: scsi device to change the state of.
2014 * @timeout: command timeout
2015 * @retries: number of retries before failing
2016 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2017 * returning sense. Make sure that this is cleared before passing
2018 * in.
2020 * Returns zero if unsuccessful or an error if TUR failed. For
2021 * removable media, UNIT_ATTENTION sets ->changed flag.
2024 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2025 struct scsi_sense_hdr *sshdr_external)
2027 char cmd[] = {
2028 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2030 struct scsi_sense_hdr *sshdr;
2031 int result;
2033 if (!sshdr_external)
2034 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2035 else
2036 sshdr = sshdr_external;
2038 /* try to eat the UNIT_ATTENTION if there are enough retries */
2039 do {
2040 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2041 timeout, retries, NULL);
2042 if (sdev->removable && scsi_sense_valid(sshdr) &&
2043 sshdr->sense_key == UNIT_ATTENTION)
2044 sdev->changed = 1;
2045 } while (scsi_sense_valid(sshdr) &&
2046 sshdr->sense_key == UNIT_ATTENTION && --retries);
2048 if (!sshdr_external)
2049 kfree(sshdr);
2050 return result;
2052 EXPORT_SYMBOL(scsi_test_unit_ready);
2055 * scsi_device_set_state - Take the given device through the device state model.
2056 * @sdev: scsi device to change the state of.
2057 * @state: state to change to.
2059 * Returns zero if unsuccessful or an error if the requested
2060 * transition is illegal.
2063 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2065 enum scsi_device_state oldstate = sdev->sdev_state;
2067 if (state == oldstate)
2068 return 0;
2070 switch (state) {
2071 case SDEV_CREATED:
2072 switch (oldstate) {
2073 case SDEV_CREATED_BLOCK:
2074 break;
2075 default:
2076 goto illegal;
2078 break;
2080 case SDEV_RUNNING:
2081 switch (oldstate) {
2082 case SDEV_CREATED:
2083 case SDEV_OFFLINE:
2084 case SDEV_QUIESCE:
2085 case SDEV_BLOCK:
2086 break;
2087 default:
2088 goto illegal;
2090 break;
2092 case SDEV_QUIESCE:
2093 switch (oldstate) {
2094 case SDEV_RUNNING:
2095 case SDEV_OFFLINE:
2096 break;
2097 default:
2098 goto illegal;
2100 break;
2102 case SDEV_OFFLINE:
2103 switch (oldstate) {
2104 case SDEV_CREATED:
2105 case SDEV_RUNNING:
2106 case SDEV_QUIESCE:
2107 case SDEV_BLOCK:
2108 break;
2109 default:
2110 goto illegal;
2112 break;
2114 case SDEV_BLOCK:
2115 switch (oldstate) {
2116 case SDEV_RUNNING:
2117 case SDEV_CREATED_BLOCK:
2118 break;
2119 default:
2120 goto illegal;
2122 break;
2124 case SDEV_CREATED_BLOCK:
2125 switch (oldstate) {
2126 case SDEV_CREATED:
2127 break;
2128 default:
2129 goto illegal;
2131 break;
2133 case SDEV_CANCEL:
2134 switch (oldstate) {
2135 case SDEV_CREATED:
2136 case SDEV_RUNNING:
2137 case SDEV_QUIESCE:
2138 case SDEV_OFFLINE:
2139 case SDEV_BLOCK:
2140 break;
2141 default:
2142 goto illegal;
2144 break;
2146 case SDEV_DEL:
2147 switch (oldstate) {
2148 case SDEV_CREATED:
2149 case SDEV_RUNNING:
2150 case SDEV_OFFLINE:
2151 case SDEV_CANCEL:
2152 break;
2153 default:
2154 goto illegal;
2156 break;
2159 sdev->sdev_state = state;
2160 return 0;
2162 illegal:
2163 SCSI_LOG_ERROR_RECOVERY(1,
2164 sdev_printk(KERN_ERR, sdev,
2165 "Illegal state transition %s->%s\n",
2166 scsi_device_state_name(oldstate),
2167 scsi_device_state_name(state))
2169 return -EINVAL;
2171 EXPORT_SYMBOL(scsi_device_set_state);
2174 * sdev_evt_emit - emit a single SCSI device uevent
2175 * @sdev: associated SCSI device
2176 * @evt: event to emit
2178 * Send a single uevent (scsi_event) to the associated scsi_device.
2180 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2182 int idx = 0;
2183 char *envp[3];
2185 switch (evt->evt_type) {
2186 case SDEV_EVT_MEDIA_CHANGE:
2187 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2188 break;
2190 default:
2191 /* do nothing */
2192 break;
2195 envp[idx++] = NULL;
2197 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2201 * sdev_evt_thread - send a uevent for each scsi event
2202 * @work: work struct for scsi_device
2204 * Dispatch queued events to their associated scsi_device kobjects
2205 * as uevents.
2207 void scsi_evt_thread(struct work_struct *work)
2209 struct scsi_device *sdev;
2210 LIST_HEAD(event_list);
2212 sdev = container_of(work, struct scsi_device, event_work);
2214 while (1) {
2215 struct scsi_event *evt;
2216 struct list_head *this, *tmp;
2217 unsigned long flags;
2219 spin_lock_irqsave(&sdev->list_lock, flags);
2220 list_splice_init(&sdev->event_list, &event_list);
2221 spin_unlock_irqrestore(&sdev->list_lock, flags);
2223 if (list_empty(&event_list))
2224 break;
2226 list_for_each_safe(this, tmp, &event_list) {
2227 evt = list_entry(this, struct scsi_event, node);
2228 list_del(&evt->node);
2229 scsi_evt_emit(sdev, evt);
2230 kfree(evt);
2236 * sdev_evt_send - send asserted event to uevent thread
2237 * @sdev: scsi_device event occurred on
2238 * @evt: event to send
2240 * Assert scsi device event asynchronously.
2242 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2244 unsigned long flags;
2246 #if 0
2247 /* FIXME: currently this check eliminates all media change events
2248 * for polled devices. Need to update to discriminate between AN
2249 * and polled events */
2250 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2251 kfree(evt);
2252 return;
2254 #endif
2256 spin_lock_irqsave(&sdev->list_lock, flags);
2257 list_add_tail(&evt->node, &sdev->event_list);
2258 schedule_work(&sdev->event_work);
2259 spin_unlock_irqrestore(&sdev->list_lock, flags);
2261 EXPORT_SYMBOL_GPL(sdev_evt_send);
2264 * sdev_evt_alloc - allocate a new scsi event
2265 * @evt_type: type of event to allocate
2266 * @gfpflags: GFP flags for allocation
2268 * Allocates and returns a new scsi_event.
2270 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2271 gfp_t gfpflags)
2273 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2274 if (!evt)
2275 return NULL;
2277 evt->evt_type = evt_type;
2278 INIT_LIST_HEAD(&evt->node);
2280 /* evt_type-specific initialization, if any */
2281 switch (evt_type) {
2282 case SDEV_EVT_MEDIA_CHANGE:
2283 default:
2284 /* do nothing */
2285 break;
2288 return evt;
2290 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2293 * sdev_evt_send_simple - send asserted event to uevent thread
2294 * @sdev: scsi_device event occurred on
2295 * @evt_type: type of event to send
2296 * @gfpflags: GFP flags for allocation
2298 * Assert scsi device event asynchronously, given an event type.
2300 void sdev_evt_send_simple(struct scsi_device *sdev,
2301 enum scsi_device_event evt_type, gfp_t gfpflags)
2303 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2304 if (!evt) {
2305 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2306 evt_type);
2307 return;
2310 sdev_evt_send(sdev, evt);
2312 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2315 * scsi_device_quiesce - Block user issued commands.
2316 * @sdev: scsi device to quiesce.
2318 * This works by trying to transition to the SDEV_QUIESCE state
2319 * (which must be a legal transition). When the device is in this
2320 * state, only special requests will be accepted, all others will
2321 * be deferred. Since special requests may also be requeued requests,
2322 * a successful return doesn't guarantee the device will be
2323 * totally quiescent.
2325 * Must be called with user context, may sleep.
2327 * Returns zero if unsuccessful or an error if not.
2330 scsi_device_quiesce(struct scsi_device *sdev)
2332 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2333 if (err)
2334 return err;
2336 scsi_run_queue(sdev->request_queue);
2337 while (sdev->device_busy) {
2338 msleep_interruptible(200);
2339 scsi_run_queue(sdev->request_queue);
2341 return 0;
2343 EXPORT_SYMBOL(scsi_device_quiesce);
2346 * scsi_device_resume - Restart user issued commands to a quiesced device.
2347 * @sdev: scsi device to resume.
2349 * Moves the device from quiesced back to running and restarts the
2350 * queues.
2352 * Must be called with user context, may sleep.
2354 void
2355 scsi_device_resume(struct scsi_device *sdev)
2357 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2358 return;
2359 scsi_run_queue(sdev->request_queue);
2361 EXPORT_SYMBOL(scsi_device_resume);
2363 static void
2364 device_quiesce_fn(struct scsi_device *sdev, void *data)
2366 scsi_device_quiesce(sdev);
2369 void
2370 scsi_target_quiesce(struct scsi_target *starget)
2372 starget_for_each_device(starget, NULL, device_quiesce_fn);
2374 EXPORT_SYMBOL(scsi_target_quiesce);
2376 static void
2377 device_resume_fn(struct scsi_device *sdev, void *data)
2379 scsi_device_resume(sdev);
2382 void
2383 scsi_target_resume(struct scsi_target *starget)
2385 starget_for_each_device(starget, NULL, device_resume_fn);
2387 EXPORT_SYMBOL(scsi_target_resume);
2390 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2391 * @sdev: device to block
2393 * Block request made by scsi lld's to temporarily stop all
2394 * scsi commands on the specified device. Called from interrupt
2395 * or normal process context.
2397 * Returns zero if successful or error if not
2399 * Notes:
2400 * This routine transitions the device to the SDEV_BLOCK state
2401 * (which must be a legal transition). When the device is in this
2402 * state, all commands are deferred until the scsi lld reenables
2403 * the device with scsi_device_unblock or device_block_tmo fires.
2404 * This routine assumes the host_lock is held on entry.
2407 scsi_internal_device_block(struct scsi_device *sdev)
2409 struct request_queue *q = sdev->request_queue;
2410 unsigned long flags;
2411 int err = 0;
2413 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2414 if (err) {
2415 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2417 if (err)
2418 return err;
2422 * The device has transitioned to SDEV_BLOCK. Stop the
2423 * block layer from calling the midlayer with this device's
2424 * request queue.
2426 spin_lock_irqsave(q->queue_lock, flags);
2427 blk_stop_queue(q);
2428 spin_unlock_irqrestore(q->queue_lock, flags);
2430 return 0;
2432 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2435 * scsi_internal_device_unblock - resume a device after a block request
2436 * @sdev: device to resume
2438 * Called by scsi lld's or the midlayer to restart the device queue
2439 * for the previously suspended scsi device. Called from interrupt or
2440 * normal process context.
2442 * Returns zero if successful or error if not.
2444 * Notes:
2445 * This routine transitions the device to the SDEV_RUNNING state
2446 * (which must be a legal transition) allowing the midlayer to
2447 * goose the queue for this device. This routine assumes the
2448 * host_lock is held upon entry.
2451 scsi_internal_device_unblock(struct scsi_device *sdev)
2453 struct request_queue *q = sdev->request_queue;
2454 unsigned long flags;
2457 * Try to transition the scsi device to SDEV_RUNNING
2458 * and goose the device queue if successful.
2460 if (sdev->sdev_state == SDEV_BLOCK)
2461 sdev->sdev_state = SDEV_RUNNING;
2462 else if (sdev->sdev_state == SDEV_CREATED_BLOCK)
2463 sdev->sdev_state = SDEV_CREATED;
2464 else if (sdev->sdev_state != SDEV_CANCEL &&
2465 sdev->sdev_state != SDEV_OFFLINE)
2466 return -EINVAL;
2468 spin_lock_irqsave(q->queue_lock, flags);
2469 blk_start_queue(q);
2470 spin_unlock_irqrestore(q->queue_lock, flags);
2472 return 0;
2474 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2476 static void
2477 device_block(struct scsi_device *sdev, void *data)
2479 scsi_internal_device_block(sdev);
2482 static int
2483 target_block(struct device *dev, void *data)
2485 if (scsi_is_target_device(dev))
2486 starget_for_each_device(to_scsi_target(dev), NULL,
2487 device_block);
2488 return 0;
2491 void
2492 scsi_target_block(struct device *dev)
2494 if (scsi_is_target_device(dev))
2495 starget_for_each_device(to_scsi_target(dev), NULL,
2496 device_block);
2497 else
2498 device_for_each_child(dev, NULL, target_block);
2500 EXPORT_SYMBOL_GPL(scsi_target_block);
2502 static void
2503 device_unblock(struct scsi_device *sdev, void *data)
2505 scsi_internal_device_unblock(sdev);
2508 static int
2509 target_unblock(struct device *dev, void *data)
2511 if (scsi_is_target_device(dev))
2512 starget_for_each_device(to_scsi_target(dev), NULL,
2513 device_unblock);
2514 return 0;
2517 void
2518 scsi_target_unblock(struct device *dev)
2520 if (scsi_is_target_device(dev))
2521 starget_for_each_device(to_scsi_target(dev), NULL,
2522 device_unblock);
2523 else
2524 device_for_each_child(dev, NULL, target_unblock);
2526 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2529 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2530 * @sgl: scatter-gather list
2531 * @sg_count: number of segments in sg
2532 * @offset: offset in bytes into sg, on return offset into the mapped area
2533 * @len: bytes to map, on return number of bytes mapped
2535 * Returns virtual address of the start of the mapped page
2537 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2538 size_t *offset, size_t *len)
2540 int i;
2541 size_t sg_len = 0, len_complete = 0;
2542 struct scatterlist *sg;
2543 struct page *page;
2545 WARN_ON(!irqs_disabled());
2547 for_each_sg(sgl, sg, sg_count, i) {
2548 len_complete = sg_len; /* Complete sg-entries */
2549 sg_len += sg->length;
2550 if (sg_len > *offset)
2551 break;
2554 if (unlikely(i == sg_count)) {
2555 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2556 "elements %d\n",
2557 __func__, sg_len, *offset, sg_count);
2558 WARN_ON(1);
2559 return NULL;
2562 /* Offset starting from the beginning of first page in this sg-entry */
2563 *offset = *offset - len_complete + sg->offset;
2565 /* Assumption: contiguous pages can be accessed as "page + i" */
2566 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2567 *offset &= ~PAGE_MASK;
2569 /* Bytes in this sg-entry from *offset to the end of the page */
2570 sg_len = PAGE_SIZE - *offset;
2571 if (*len > sg_len)
2572 *len = sg_len;
2574 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2576 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2579 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2580 * @virt: virtual address to be unmapped
2582 void scsi_kunmap_atomic_sg(void *virt)
2584 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2586 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);