TTY: serial, remove dead code from 68328
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / scsi / scsi_lib.c
blobfc3f168decb4606cf479e5b6878236f9cfb5ca24
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/mempool.h>
16 #include <linux/slab.h>
17 #include <linux/init.h>
18 #include <linux/pci.h>
19 #include <linux/delay.h>
20 #include <linux/hardirq.h>
21 #include <linux/scatterlist.h>
23 #include <scsi/scsi.h>
24 #include <scsi/scsi_cmnd.h>
25 #include <scsi/scsi_dbg.h>
26 #include <scsi/scsi_device.h>
27 #include <scsi/scsi_driver.h>
28 #include <scsi/scsi_eh.h>
29 #include <scsi/scsi_host.h>
31 #include "scsi_priv.h"
32 #include "scsi_logging.h"
35 #define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
36 #define SG_MEMPOOL_SIZE 2
38 struct scsi_host_sg_pool {
39 size_t size;
40 char *name;
41 struct kmem_cache *slab;
42 mempool_t *pool;
45 #define SP(x) { x, "sgpool-" __stringify(x) }
46 #if (SCSI_MAX_SG_SEGMENTS < 32)
47 #error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
48 #endif
49 static struct scsi_host_sg_pool scsi_sg_pools[] = {
50 SP(8),
51 SP(16),
52 #if (SCSI_MAX_SG_SEGMENTS > 32)
53 SP(32),
54 #if (SCSI_MAX_SG_SEGMENTS > 64)
55 SP(64),
56 #if (SCSI_MAX_SG_SEGMENTS > 128)
57 SP(128),
58 #if (SCSI_MAX_SG_SEGMENTS > 256)
59 #error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
60 #endif
61 #endif
62 #endif
63 #endif
64 SP(SCSI_MAX_SG_SEGMENTS)
66 #undef SP
68 struct kmem_cache *scsi_sdb_cache;
71 * When to reinvoke queueing after a resource shortage. It's 3 msecs to
72 * not change behaviour from the previous unplug mechanism, experimentation
73 * may prove this needs changing.
75 #define SCSI_QUEUE_DELAY 3
78 * Function: scsi_unprep_request()
80 * Purpose: Remove all preparation done for a request, including its
81 * associated scsi_cmnd, so that it can be requeued.
83 * Arguments: req - request to unprepare
85 * Lock status: Assumed that no locks are held upon entry.
87 * Returns: Nothing.
89 static void scsi_unprep_request(struct request *req)
91 struct scsi_cmnd *cmd = req->special;
93 blk_unprep_request(req);
94 req->special = NULL;
96 scsi_put_command(cmd);
99 /**
100 * __scsi_queue_insert - private queue insertion
101 * @cmd: The SCSI command being requeued
102 * @reason: The reason for the requeue
103 * @unbusy: Whether the queue should be unbusied
105 * This is a private queue insertion. The public interface
106 * scsi_queue_insert() always assumes the queue should be unbusied
107 * because it's always called before the completion. This function is
108 * for a requeue after completion, which should only occur in this
109 * file.
111 static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
113 struct Scsi_Host *host = cmd->device->host;
114 struct scsi_device *device = cmd->device;
115 struct scsi_target *starget = scsi_target(device);
116 struct request_queue *q = device->request_queue;
117 unsigned long flags;
119 SCSI_LOG_MLQUEUE(1,
120 printk("Inserting command %p into mlqueue\n", cmd));
123 * Set the appropriate busy bit for the device/host.
125 * If the host/device isn't busy, assume that something actually
126 * completed, and that we should be able to queue a command now.
128 * Note that the prior mid-layer assumption that any host could
129 * always queue at least one command is now broken. The mid-layer
130 * will implement a user specifiable stall (see
131 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
132 * if a command is requeued with no other commands outstanding
133 * either for the device or for the host.
135 switch (reason) {
136 case SCSI_MLQUEUE_HOST_BUSY:
137 host->host_blocked = host->max_host_blocked;
138 break;
139 case SCSI_MLQUEUE_DEVICE_BUSY:
140 case SCSI_MLQUEUE_EH_RETRY:
141 device->device_blocked = device->max_device_blocked;
142 break;
143 case SCSI_MLQUEUE_TARGET_BUSY:
144 starget->target_blocked = starget->max_target_blocked;
145 break;
149 * Decrement the counters, since these commands are no longer
150 * active on the host/device.
152 if (unbusy)
153 scsi_device_unbusy(device);
156 * Requeue this command. It will go before all other commands
157 * that are already in the queue.
159 spin_lock_irqsave(q->queue_lock, flags);
160 blk_requeue_request(q, cmd->request);
161 spin_unlock_irqrestore(q->queue_lock, flags);
163 kblockd_schedule_work(q, &device->requeue_work);
165 return 0;
169 * Function: scsi_queue_insert()
171 * Purpose: Insert a command in the midlevel queue.
173 * Arguments: cmd - command that we are adding to queue.
174 * reason - why we are inserting command to queue.
176 * Lock status: Assumed that lock is not held upon entry.
178 * Returns: Nothing.
180 * Notes: We do this for one of two cases. Either the host is busy
181 * and it cannot accept any more commands for the time being,
182 * or the device returned QUEUE_FULL and can accept no more
183 * commands.
184 * Notes: This could be called either from an interrupt context or a
185 * normal process context.
187 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
189 return __scsi_queue_insert(cmd, reason, 1);
192 * scsi_execute - insert request and wait for the result
193 * @sdev: scsi device
194 * @cmd: scsi command
195 * @data_direction: data direction
196 * @buffer: data buffer
197 * @bufflen: len of buffer
198 * @sense: optional sense buffer
199 * @timeout: request timeout in seconds
200 * @retries: number of times to retry request
201 * @flags: or into request flags;
202 * @resid: optional residual length
204 * returns the req->errors value which is the scsi_cmnd result
205 * field.
207 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
208 int data_direction, void *buffer, unsigned bufflen,
209 unsigned char *sense, int timeout, int retries, int flags,
210 int *resid)
212 struct request *req;
213 int write = (data_direction == DMA_TO_DEVICE);
214 int ret = DRIVER_ERROR << 24;
216 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
217 if (!req)
218 return ret;
220 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
221 buffer, bufflen, __GFP_WAIT))
222 goto out;
224 req->cmd_len = COMMAND_SIZE(cmd[0]);
225 memcpy(req->cmd, cmd, req->cmd_len);
226 req->sense = sense;
227 req->sense_len = 0;
228 req->retries = retries;
229 req->timeout = timeout;
230 req->cmd_type = REQ_TYPE_BLOCK_PC;
231 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
234 * head injection *required* here otherwise quiesce won't work
236 blk_execute_rq(req->q, NULL, req, 1);
239 * Some devices (USB mass-storage in particular) may transfer
240 * garbage data together with a residue indicating that the data
241 * is invalid. Prevent the garbage from being misinterpreted
242 * and prevent security leaks by zeroing out the excess data.
244 if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
245 memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
247 if (resid)
248 *resid = req->resid_len;
249 ret = req->errors;
250 out:
251 blk_put_request(req);
253 return ret;
255 EXPORT_SYMBOL(scsi_execute);
258 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
259 int data_direction, void *buffer, unsigned bufflen,
260 struct scsi_sense_hdr *sshdr, int timeout, int retries,
261 int *resid)
263 char *sense = NULL;
264 int result;
266 if (sshdr) {
267 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
268 if (!sense)
269 return DRIVER_ERROR << 24;
271 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
272 sense, timeout, retries, 0, resid);
273 if (sshdr)
274 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
276 kfree(sense);
277 return result;
279 EXPORT_SYMBOL(scsi_execute_req);
282 * Function: scsi_init_cmd_errh()
284 * Purpose: Initialize cmd fields related to error handling.
286 * Arguments: cmd - command that is ready to be queued.
288 * Notes: This function has the job of initializing a number of
289 * fields related to error handling. Typically this will
290 * be called once for each command, as required.
292 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
294 cmd->serial_number = 0;
295 scsi_set_resid(cmd, 0);
296 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
297 if (cmd->cmd_len == 0)
298 cmd->cmd_len = scsi_command_size(cmd->cmnd);
301 void scsi_device_unbusy(struct scsi_device *sdev)
303 struct Scsi_Host *shost = sdev->host;
304 struct scsi_target *starget = scsi_target(sdev);
305 unsigned long flags;
307 spin_lock_irqsave(shost->host_lock, flags);
308 shost->host_busy--;
309 starget->target_busy--;
310 if (unlikely(scsi_host_in_recovery(shost) &&
311 (shost->host_failed || shost->host_eh_scheduled)))
312 scsi_eh_wakeup(shost);
313 spin_unlock(shost->host_lock);
314 spin_lock(sdev->request_queue->queue_lock);
315 sdev->device_busy--;
316 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
320 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
321 * and call blk_run_queue for all the scsi_devices on the target -
322 * including current_sdev first.
324 * Called with *no* scsi locks held.
326 static void scsi_single_lun_run(struct scsi_device *current_sdev)
328 struct Scsi_Host *shost = current_sdev->host;
329 struct scsi_device *sdev, *tmp;
330 struct scsi_target *starget = scsi_target(current_sdev);
331 unsigned long flags;
333 spin_lock_irqsave(shost->host_lock, flags);
334 starget->starget_sdev_user = NULL;
335 spin_unlock_irqrestore(shost->host_lock, flags);
338 * Call blk_run_queue for all LUNs on the target, starting with
339 * current_sdev. We race with others (to set starget_sdev_user),
340 * but in most cases, we will be first. Ideally, each LU on the
341 * target would get some limited time or requests on the target.
343 blk_run_queue(current_sdev->request_queue);
345 spin_lock_irqsave(shost->host_lock, flags);
346 if (starget->starget_sdev_user)
347 goto out;
348 list_for_each_entry_safe(sdev, tmp, &starget->devices,
349 same_target_siblings) {
350 if (sdev == current_sdev)
351 continue;
352 if (scsi_device_get(sdev))
353 continue;
355 spin_unlock_irqrestore(shost->host_lock, flags);
356 blk_run_queue(sdev->request_queue);
357 spin_lock_irqsave(shost->host_lock, flags);
359 scsi_device_put(sdev);
361 out:
362 spin_unlock_irqrestore(shost->host_lock, flags);
365 static inline int scsi_device_is_busy(struct scsi_device *sdev)
367 if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
368 return 1;
370 return 0;
373 static inline int scsi_target_is_busy(struct scsi_target *starget)
375 return ((starget->can_queue > 0 &&
376 starget->target_busy >= starget->can_queue) ||
377 starget->target_blocked);
380 static inline int scsi_host_is_busy(struct Scsi_Host *shost)
382 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
383 shost->host_blocked || shost->host_self_blocked)
384 return 1;
386 return 0;
390 * Function: scsi_run_queue()
392 * Purpose: Select a proper request queue to serve next
394 * Arguments: q - last request's queue
396 * Returns: Nothing
398 * Notes: The previous command was completely finished, start
399 * a new one if possible.
401 static void scsi_run_queue(struct request_queue *q)
403 struct scsi_device *sdev = q->queuedata;
404 struct Scsi_Host *shost;
405 LIST_HEAD(starved_list);
406 unsigned long flags;
408 /* if the device is dead, sdev will be NULL, so no queue to run */
409 if (!sdev)
410 return;
412 shost = sdev->host;
413 if (scsi_target(sdev)->single_lun)
414 scsi_single_lun_run(sdev);
416 spin_lock_irqsave(shost->host_lock, flags);
417 list_splice_init(&shost->starved_list, &starved_list);
419 while (!list_empty(&starved_list)) {
421 * As long as shost is accepting commands and we have
422 * starved queues, call blk_run_queue. scsi_request_fn
423 * drops the queue_lock and can add us back to the
424 * starved_list.
426 * host_lock protects the starved_list and starved_entry.
427 * scsi_request_fn must get the host_lock before checking
428 * or modifying starved_list or starved_entry.
430 if (scsi_host_is_busy(shost))
431 break;
433 sdev = list_entry(starved_list.next,
434 struct scsi_device, starved_entry);
435 list_del_init(&sdev->starved_entry);
436 if (scsi_target_is_busy(scsi_target(sdev))) {
437 list_move_tail(&sdev->starved_entry,
438 &shost->starved_list);
439 continue;
442 spin_unlock(shost->host_lock);
443 spin_lock(sdev->request_queue->queue_lock);
444 __blk_run_queue(sdev->request_queue);
445 spin_unlock(sdev->request_queue->queue_lock);
446 spin_lock(shost->host_lock);
448 /* put any unprocessed entries back */
449 list_splice(&starved_list, &shost->starved_list);
450 spin_unlock_irqrestore(shost->host_lock, flags);
452 blk_run_queue(q);
455 void scsi_requeue_run_queue(struct work_struct *work)
457 struct scsi_device *sdev;
458 struct request_queue *q;
460 sdev = container_of(work, struct scsi_device, requeue_work);
461 q = sdev->request_queue;
462 scsi_run_queue(q);
466 * Function: scsi_requeue_command()
468 * Purpose: Handle post-processing of completed commands.
470 * Arguments: q - queue to operate on
471 * cmd - command that may need to be requeued.
473 * Returns: Nothing
475 * Notes: After command completion, there may be blocks left
476 * over which weren't finished by the previous command
477 * this can be for a number of reasons - the main one is
478 * I/O errors in the middle of the request, in which case
479 * we need to request the blocks that come after the bad
480 * sector.
481 * Notes: Upon return, cmd is a stale pointer.
483 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
485 struct request *req = cmd->request;
486 unsigned long flags;
488 spin_lock_irqsave(q->queue_lock, flags);
489 scsi_unprep_request(req);
490 blk_requeue_request(q, req);
491 spin_unlock_irqrestore(q->queue_lock, flags);
493 scsi_run_queue(q);
496 void scsi_next_command(struct scsi_cmnd *cmd)
498 struct scsi_device *sdev = cmd->device;
499 struct request_queue *q = sdev->request_queue;
501 /* need to hold a reference on the device before we let go of the cmd */
502 get_device(&sdev->sdev_gendev);
504 scsi_put_command(cmd);
505 scsi_run_queue(q);
507 /* ok to remove device now */
508 put_device(&sdev->sdev_gendev);
511 void scsi_run_host_queues(struct Scsi_Host *shost)
513 struct scsi_device *sdev;
515 shost_for_each_device(sdev, shost)
516 scsi_run_queue(sdev->request_queue);
519 static void __scsi_release_buffers(struct scsi_cmnd *, int);
522 * Function: scsi_end_request()
524 * Purpose: Post-processing of completed commands (usually invoked at end
525 * of upper level post-processing and scsi_io_completion).
527 * Arguments: cmd - command that is complete.
528 * error - 0 if I/O indicates success, < 0 for I/O error.
529 * bytes - number of bytes of completed I/O
530 * requeue - indicates whether we should requeue leftovers.
532 * Lock status: Assumed that lock is not held upon entry.
534 * Returns: cmd if requeue required, NULL otherwise.
536 * Notes: This is called for block device requests in order to
537 * mark some number of sectors as complete.
539 * We are guaranteeing that the request queue will be goosed
540 * at some point during this call.
541 * Notes: If cmd was requeued, upon return it will be a stale pointer.
543 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
544 int bytes, int requeue)
546 struct request_queue *q = cmd->device->request_queue;
547 struct request *req = cmd->request;
550 * If there are blocks left over at the end, set up the command
551 * to queue the remainder of them.
553 if (blk_end_request(req, error, bytes)) {
554 /* kill remainder if no retrys */
555 if (error && scsi_noretry_cmd(cmd))
556 blk_end_request_all(req, error);
557 else {
558 if (requeue) {
560 * Bleah. Leftovers again. Stick the
561 * leftovers in the front of the
562 * queue, and goose the queue again.
564 scsi_release_buffers(cmd);
565 scsi_requeue_command(q, cmd);
566 cmd = NULL;
568 return cmd;
573 * This will goose the queue request function at the end, so we don't
574 * need to worry about launching another command.
576 __scsi_release_buffers(cmd, 0);
577 scsi_next_command(cmd);
578 return NULL;
581 static inline unsigned int scsi_sgtable_index(unsigned short nents)
583 unsigned int index;
585 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
587 if (nents <= 8)
588 index = 0;
589 else
590 index = get_count_order(nents) - 3;
592 return index;
595 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
597 struct scsi_host_sg_pool *sgp;
599 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
600 mempool_free(sgl, sgp->pool);
603 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
605 struct scsi_host_sg_pool *sgp;
607 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
608 return mempool_alloc(sgp->pool, gfp_mask);
611 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
612 gfp_t gfp_mask)
614 int ret;
616 BUG_ON(!nents);
618 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
619 gfp_mask, scsi_sg_alloc);
620 if (unlikely(ret))
621 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
622 scsi_sg_free);
624 return ret;
627 static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
629 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
632 static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
635 if (cmd->sdb.table.nents)
636 scsi_free_sgtable(&cmd->sdb);
638 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
640 if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
641 struct scsi_data_buffer *bidi_sdb =
642 cmd->request->next_rq->special;
643 scsi_free_sgtable(bidi_sdb);
644 kmem_cache_free(scsi_sdb_cache, bidi_sdb);
645 cmd->request->next_rq->special = NULL;
648 if (scsi_prot_sg_count(cmd))
649 scsi_free_sgtable(cmd->prot_sdb);
653 * Function: scsi_release_buffers()
655 * Purpose: Completion processing for block device I/O requests.
657 * Arguments: cmd - command that we are bailing.
659 * Lock status: Assumed that no lock is held upon entry.
661 * Returns: Nothing
663 * Notes: In the event that an upper level driver rejects a
664 * command, we must release resources allocated during
665 * the __init_io() function. Primarily this would involve
666 * the scatter-gather table, and potentially any bounce
667 * buffers.
669 void scsi_release_buffers(struct scsi_cmnd *cmd)
671 __scsi_release_buffers(cmd, 1);
673 EXPORT_SYMBOL(scsi_release_buffers);
675 static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
677 int error = 0;
679 switch(host_byte(result)) {
680 case DID_TRANSPORT_FAILFAST:
681 error = -ENOLINK;
682 break;
683 case DID_TARGET_FAILURE:
684 cmd->result |= (DID_OK << 16);
685 error = -EREMOTEIO;
686 break;
687 case DID_NEXUS_FAILURE:
688 cmd->result |= (DID_OK << 16);
689 error = -EBADE;
690 break;
691 default:
692 error = -EIO;
693 break;
696 return error;
700 * Function: scsi_io_completion()
702 * Purpose: Completion processing for block device I/O requests.
704 * Arguments: cmd - command that is finished.
706 * Lock status: Assumed that no lock is held upon entry.
708 * Returns: Nothing
710 * Notes: This function is matched in terms of capabilities to
711 * the function that created the scatter-gather list.
712 * In other words, if there are no bounce buffers
713 * (the normal case for most drivers), we don't need
714 * the logic to deal with cleaning up afterwards.
716 * We must call scsi_end_request(). This will finish off
717 * the specified number of sectors. If we are done, the
718 * command block will be released and the queue function
719 * will be goosed. If we are not done then we have to
720 * figure out what to do next:
722 * a) We can call scsi_requeue_command(). The request
723 * will be unprepared and put back on the queue. Then
724 * a new command will be created for it. This should
725 * be used if we made forward progress, or if we want
726 * to switch from READ(10) to READ(6) for example.
728 * b) We can call scsi_queue_insert(). The request will
729 * be put back on the queue and retried using the same
730 * command as before, possibly after a delay.
732 * c) We can call blk_end_request() with -EIO to fail
733 * the remainder of the request.
735 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
737 int result = cmd->result;
738 struct request_queue *q = cmd->device->request_queue;
739 struct request *req = cmd->request;
740 int error = 0;
741 struct scsi_sense_hdr sshdr;
742 int sense_valid = 0;
743 int sense_deferred = 0;
744 enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
745 ACTION_DELAYED_RETRY} action;
746 char *description = NULL;
748 if (result) {
749 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
750 if (sense_valid)
751 sense_deferred = scsi_sense_is_deferred(&sshdr);
754 if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
755 req->errors = result;
756 if (result) {
757 if (sense_valid && req->sense) {
759 * SG_IO wants current and deferred errors
761 int len = 8 + cmd->sense_buffer[7];
763 if (len > SCSI_SENSE_BUFFERSIZE)
764 len = SCSI_SENSE_BUFFERSIZE;
765 memcpy(req->sense, cmd->sense_buffer, len);
766 req->sense_len = len;
768 if (!sense_deferred)
769 error = __scsi_error_from_host_byte(cmd, result);
772 req->resid_len = scsi_get_resid(cmd);
774 if (scsi_bidi_cmnd(cmd)) {
776 * Bidi commands Must be complete as a whole,
777 * both sides at once.
779 req->next_rq->resid_len = scsi_in(cmd)->resid;
781 scsi_release_buffers(cmd);
782 blk_end_request_all(req, 0);
784 scsi_next_command(cmd);
785 return;
789 /* no bidi support for !REQ_TYPE_BLOCK_PC yet */
790 BUG_ON(blk_bidi_rq(req));
793 * Next deal with any sectors which we were able to correctly
794 * handle.
796 SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, "
797 "%d bytes done.\n",
798 blk_rq_sectors(req), good_bytes));
801 * Recovered errors need reporting, but they're always treated
802 * as success, so fiddle the result code here. For BLOCK_PC
803 * we already took a copy of the original into rq->errors which
804 * is what gets returned to the user
806 if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
807 /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
808 * print since caller wants ATA registers. Only occurs on
809 * SCSI ATA PASS_THROUGH commands when CK_COND=1
811 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
813 else if (!(req->cmd_flags & REQ_QUIET))
814 scsi_print_sense("", cmd);
815 result = 0;
816 /* BLOCK_PC may have set error */
817 error = 0;
821 * A number of bytes were successfully read. If there
822 * are leftovers and there is some kind of error
823 * (result != 0), retry the rest.
825 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
826 return;
828 error = __scsi_error_from_host_byte(cmd, result);
830 if (host_byte(result) == DID_RESET) {
831 /* Third party bus reset or reset for error recovery
832 * reasons. Just retry the command and see what
833 * happens.
835 action = ACTION_RETRY;
836 } else if (sense_valid && !sense_deferred) {
837 switch (sshdr.sense_key) {
838 case UNIT_ATTENTION:
839 if (cmd->device->removable) {
840 /* Detected disc change. Set a bit
841 * and quietly refuse further access.
843 cmd->device->changed = 1;
844 description = "Media Changed";
845 action = ACTION_FAIL;
846 } else {
847 /* Must have been a power glitch, or a
848 * bus reset. Could not have been a
849 * media change, so we just retry the
850 * command and see what happens.
852 action = ACTION_RETRY;
854 break;
855 case ILLEGAL_REQUEST:
856 /* If we had an ILLEGAL REQUEST returned, then
857 * we may have performed an unsupported
858 * command. The only thing this should be
859 * would be a ten byte read where only a six
860 * byte read was supported. Also, on a system
861 * where READ CAPACITY failed, we may have
862 * read past the end of the disk.
864 if ((cmd->device->use_10_for_rw &&
865 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
866 (cmd->cmnd[0] == READ_10 ||
867 cmd->cmnd[0] == WRITE_10)) {
868 /* This will issue a new 6-byte command. */
869 cmd->device->use_10_for_rw = 0;
870 action = ACTION_REPREP;
871 } else if (sshdr.asc == 0x10) /* DIX */ {
872 description = "Host Data Integrity Failure";
873 action = ACTION_FAIL;
874 error = -EILSEQ;
875 /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
876 } else if ((sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
877 (cmd->cmnd[0] == UNMAP ||
878 cmd->cmnd[0] == WRITE_SAME_16 ||
879 cmd->cmnd[0] == WRITE_SAME)) {
880 description = "Discard failure";
881 action = ACTION_FAIL;
882 } else
883 action = ACTION_FAIL;
884 break;
885 case ABORTED_COMMAND:
886 action = ACTION_FAIL;
887 if (sshdr.asc == 0x10) { /* DIF */
888 description = "Target Data Integrity Failure";
889 error = -EILSEQ;
891 break;
892 case NOT_READY:
893 /* If the device is in the process of becoming
894 * ready, or has a temporary blockage, retry.
896 if (sshdr.asc == 0x04) {
897 switch (sshdr.ascq) {
898 case 0x01: /* becoming ready */
899 case 0x04: /* format in progress */
900 case 0x05: /* rebuild in progress */
901 case 0x06: /* recalculation in progress */
902 case 0x07: /* operation in progress */
903 case 0x08: /* Long write in progress */
904 case 0x09: /* self test in progress */
905 case 0x14: /* space allocation in progress */
906 action = ACTION_DELAYED_RETRY;
907 break;
908 default:
909 description = "Device not ready";
910 action = ACTION_FAIL;
911 break;
913 } else {
914 description = "Device not ready";
915 action = ACTION_FAIL;
917 break;
918 case VOLUME_OVERFLOW:
919 /* See SSC3rXX or current. */
920 action = ACTION_FAIL;
921 break;
922 default:
923 description = "Unhandled sense code";
924 action = ACTION_FAIL;
925 break;
927 } else {
928 description = "Unhandled error code";
929 action = ACTION_FAIL;
932 switch (action) {
933 case ACTION_FAIL:
934 /* Give up and fail the remainder of the request */
935 scsi_release_buffers(cmd);
936 if (!(req->cmd_flags & REQ_QUIET)) {
937 if (description)
938 scmd_printk(KERN_INFO, cmd, "%s\n",
939 description);
940 scsi_print_result(cmd);
941 if (driver_byte(result) & DRIVER_SENSE)
942 scsi_print_sense("", cmd);
943 scsi_print_command(cmd);
945 if (blk_end_request_err(req, error))
946 scsi_requeue_command(q, cmd);
947 else
948 scsi_next_command(cmd);
949 break;
950 case ACTION_REPREP:
951 /* Unprep the request and put it back at the head of the queue.
952 * A new command will be prepared and issued.
954 scsi_release_buffers(cmd);
955 scsi_requeue_command(q, cmd);
956 break;
957 case ACTION_RETRY:
958 /* Retry the same command immediately */
959 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
960 break;
961 case ACTION_DELAYED_RETRY:
962 /* Retry the same command after a delay */
963 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
964 break;
968 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
969 gfp_t gfp_mask)
971 int count;
974 * If sg table allocation fails, requeue request later.
976 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
977 gfp_mask))) {
978 return BLKPREP_DEFER;
981 req->buffer = NULL;
984 * Next, walk the list, and fill in the addresses and sizes of
985 * each segment.
987 count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
988 BUG_ON(count > sdb->table.nents);
989 sdb->table.nents = count;
990 sdb->length = blk_rq_bytes(req);
991 return BLKPREP_OK;
995 * Function: scsi_init_io()
997 * Purpose: SCSI I/O initialize function.
999 * Arguments: cmd - Command descriptor we wish to initialize
1001 * Returns: 0 on success
1002 * BLKPREP_DEFER if the failure is retryable
1003 * BLKPREP_KILL if the failure is fatal
1005 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1007 struct request *rq = cmd->request;
1009 int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask);
1010 if (error)
1011 goto err_exit;
1013 if (blk_bidi_rq(rq)) {
1014 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1015 scsi_sdb_cache, GFP_ATOMIC);
1016 if (!bidi_sdb) {
1017 error = BLKPREP_DEFER;
1018 goto err_exit;
1021 rq->next_rq->special = bidi_sdb;
1022 error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC);
1023 if (error)
1024 goto err_exit;
1027 if (blk_integrity_rq(rq)) {
1028 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1029 int ivecs, count;
1031 BUG_ON(prot_sdb == NULL);
1032 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1034 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1035 error = BLKPREP_DEFER;
1036 goto err_exit;
1039 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1040 prot_sdb->table.sgl);
1041 BUG_ON(unlikely(count > ivecs));
1042 BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1044 cmd->prot_sdb = prot_sdb;
1045 cmd->prot_sdb->table.nents = count;
1048 return BLKPREP_OK ;
1050 err_exit:
1051 scsi_release_buffers(cmd);
1052 cmd->request->special = NULL;
1053 scsi_put_command(cmd);
1054 return error;
1056 EXPORT_SYMBOL(scsi_init_io);
1058 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1059 struct request *req)
1061 struct scsi_cmnd *cmd;
1063 if (!req->special) {
1064 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1065 if (unlikely(!cmd))
1066 return NULL;
1067 req->special = cmd;
1068 } else {
1069 cmd = req->special;
1072 /* pull a tag out of the request if we have one */
1073 cmd->tag = req->tag;
1074 cmd->request = req;
1076 cmd->cmnd = req->cmd;
1077 cmd->prot_op = SCSI_PROT_NORMAL;
1079 return cmd;
1082 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1084 struct scsi_cmnd *cmd;
1085 int ret = scsi_prep_state_check(sdev, req);
1087 if (ret != BLKPREP_OK)
1088 return ret;
1090 cmd = scsi_get_cmd_from_req(sdev, req);
1091 if (unlikely(!cmd))
1092 return BLKPREP_DEFER;
1095 * BLOCK_PC requests may transfer data, in which case they must
1096 * a bio attached to them. Or they might contain a SCSI command
1097 * that does not transfer data, in which case they may optionally
1098 * submit a request without an attached bio.
1100 if (req->bio) {
1101 int ret;
1103 BUG_ON(!req->nr_phys_segments);
1105 ret = scsi_init_io(cmd, GFP_ATOMIC);
1106 if (unlikely(ret))
1107 return ret;
1108 } else {
1109 BUG_ON(blk_rq_bytes(req));
1111 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1112 req->buffer = NULL;
1115 cmd->cmd_len = req->cmd_len;
1116 if (!blk_rq_bytes(req))
1117 cmd->sc_data_direction = DMA_NONE;
1118 else if (rq_data_dir(req) == WRITE)
1119 cmd->sc_data_direction = DMA_TO_DEVICE;
1120 else
1121 cmd->sc_data_direction = DMA_FROM_DEVICE;
1123 cmd->transfersize = blk_rq_bytes(req);
1124 cmd->allowed = req->retries;
1125 return BLKPREP_OK;
1127 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1130 * Setup a REQ_TYPE_FS command. These are simple read/write request
1131 * from filesystems that still need to be translated to SCSI CDBs from
1132 * the ULD.
1134 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1136 struct scsi_cmnd *cmd;
1137 int ret = scsi_prep_state_check(sdev, req);
1139 if (ret != BLKPREP_OK)
1140 return ret;
1142 if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1143 && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1144 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1145 if (ret != BLKPREP_OK)
1146 return ret;
1150 * Filesystem requests must transfer data.
1152 BUG_ON(!req->nr_phys_segments);
1154 cmd = scsi_get_cmd_from_req(sdev, req);
1155 if (unlikely(!cmd))
1156 return BLKPREP_DEFER;
1158 memset(cmd->cmnd, 0, BLK_MAX_CDB);
1159 return scsi_init_io(cmd, GFP_ATOMIC);
1161 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1163 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1165 int ret = BLKPREP_OK;
1168 * If the device is not in running state we will reject some
1169 * or all commands.
1171 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1172 switch (sdev->sdev_state) {
1173 case SDEV_OFFLINE:
1175 * If the device is offline we refuse to process any
1176 * commands. The device must be brought online
1177 * before trying any recovery commands.
1179 sdev_printk(KERN_ERR, sdev,
1180 "rejecting I/O to offline device\n");
1181 ret = BLKPREP_KILL;
1182 break;
1183 case SDEV_DEL:
1185 * If the device is fully deleted, we refuse to
1186 * process any commands as well.
1188 sdev_printk(KERN_ERR, sdev,
1189 "rejecting I/O to dead device\n");
1190 ret = BLKPREP_KILL;
1191 break;
1192 case SDEV_QUIESCE:
1193 case SDEV_BLOCK:
1194 case SDEV_CREATED_BLOCK:
1196 * If the devices is blocked we defer normal commands.
1198 if (!(req->cmd_flags & REQ_PREEMPT))
1199 ret = BLKPREP_DEFER;
1200 break;
1201 default:
1203 * For any other not fully online state we only allow
1204 * special commands. In particular any user initiated
1205 * command is not allowed.
1207 if (!(req->cmd_flags & REQ_PREEMPT))
1208 ret = BLKPREP_KILL;
1209 break;
1212 return ret;
1214 EXPORT_SYMBOL(scsi_prep_state_check);
1216 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1218 struct scsi_device *sdev = q->queuedata;
1220 switch (ret) {
1221 case BLKPREP_KILL:
1222 req->errors = DID_NO_CONNECT << 16;
1223 /* release the command and kill it */
1224 if (req->special) {
1225 struct scsi_cmnd *cmd = req->special;
1226 scsi_release_buffers(cmd);
1227 scsi_put_command(cmd);
1228 req->special = NULL;
1230 break;
1231 case BLKPREP_DEFER:
1233 * If we defer, the blk_peek_request() returns NULL, but the
1234 * queue must be restarted, so we schedule a callback to happen
1235 * shortly.
1237 if (sdev->device_busy == 0)
1238 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1239 break;
1240 default:
1241 req->cmd_flags |= REQ_DONTPREP;
1244 return ret;
1246 EXPORT_SYMBOL(scsi_prep_return);
1248 int scsi_prep_fn(struct request_queue *q, struct request *req)
1250 struct scsi_device *sdev = q->queuedata;
1251 int ret = BLKPREP_KILL;
1253 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1254 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1255 return scsi_prep_return(q, req, ret);
1257 EXPORT_SYMBOL(scsi_prep_fn);
1260 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1261 * return 0.
1263 * Called with the queue_lock held.
1265 static inline int scsi_dev_queue_ready(struct request_queue *q,
1266 struct scsi_device *sdev)
1268 if (sdev->device_busy == 0 && sdev->device_blocked) {
1270 * unblock after device_blocked iterates to zero
1272 if (--sdev->device_blocked == 0) {
1273 SCSI_LOG_MLQUEUE(3,
1274 sdev_printk(KERN_INFO, sdev,
1275 "unblocking device at zero depth\n"));
1276 } else {
1277 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1278 return 0;
1281 if (scsi_device_is_busy(sdev))
1282 return 0;
1284 return 1;
1289 * scsi_target_queue_ready: checks if there we can send commands to target
1290 * @sdev: scsi device on starget to check.
1292 * Called with the host lock held.
1294 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1295 struct scsi_device *sdev)
1297 struct scsi_target *starget = scsi_target(sdev);
1299 if (starget->single_lun) {
1300 if (starget->starget_sdev_user &&
1301 starget->starget_sdev_user != sdev)
1302 return 0;
1303 starget->starget_sdev_user = sdev;
1306 if (starget->target_busy == 0 && starget->target_blocked) {
1308 * unblock after target_blocked iterates to zero
1310 if (--starget->target_blocked == 0) {
1311 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1312 "unblocking target at zero depth\n"));
1313 } else
1314 return 0;
1317 if (scsi_target_is_busy(starget)) {
1318 if (list_empty(&sdev->starved_entry))
1319 list_add_tail(&sdev->starved_entry,
1320 &shost->starved_list);
1321 return 0;
1324 /* We're OK to process the command, so we can't be starved */
1325 if (!list_empty(&sdev->starved_entry))
1326 list_del_init(&sdev->starved_entry);
1327 return 1;
1331 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1332 * return 0. We must end up running the queue again whenever 0 is
1333 * returned, else IO can hang.
1335 * Called with host_lock held.
1337 static inline int scsi_host_queue_ready(struct request_queue *q,
1338 struct Scsi_Host *shost,
1339 struct scsi_device *sdev)
1341 if (scsi_host_in_recovery(shost))
1342 return 0;
1343 if (shost->host_busy == 0 && shost->host_blocked) {
1345 * unblock after host_blocked iterates to zero
1347 if (--shost->host_blocked == 0) {
1348 SCSI_LOG_MLQUEUE(3,
1349 printk("scsi%d unblocking host at zero depth\n",
1350 shost->host_no));
1351 } else {
1352 return 0;
1355 if (scsi_host_is_busy(shost)) {
1356 if (list_empty(&sdev->starved_entry))
1357 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1358 return 0;
1361 /* We're OK to process the command, so we can't be starved */
1362 if (!list_empty(&sdev->starved_entry))
1363 list_del_init(&sdev->starved_entry);
1365 return 1;
1369 * Busy state exporting function for request stacking drivers.
1371 * For efficiency, no lock is taken to check the busy state of
1372 * shost/starget/sdev, since the returned value is not guaranteed and
1373 * may be changed after request stacking drivers call the function,
1374 * regardless of taking lock or not.
1376 * When scsi can't dispatch I/Os anymore and needs to kill I/Os
1377 * (e.g. !sdev), scsi needs to return 'not busy'.
1378 * Otherwise, request stacking drivers may hold requests forever.
1380 static int scsi_lld_busy(struct request_queue *q)
1382 struct scsi_device *sdev = q->queuedata;
1383 struct Scsi_Host *shost;
1384 struct scsi_target *starget;
1386 if (!sdev)
1387 return 0;
1389 shost = sdev->host;
1390 starget = scsi_target(sdev);
1392 if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
1393 scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
1394 return 1;
1396 return 0;
1400 * Kill a request for a dead device
1402 static void scsi_kill_request(struct request *req, struct request_queue *q)
1404 struct scsi_cmnd *cmd = req->special;
1405 struct scsi_device *sdev;
1406 struct scsi_target *starget;
1407 struct Scsi_Host *shost;
1409 blk_start_request(req);
1411 sdev = cmd->device;
1412 starget = scsi_target(sdev);
1413 shost = sdev->host;
1414 scsi_init_cmd_errh(cmd);
1415 cmd->result = DID_NO_CONNECT << 16;
1416 atomic_inc(&cmd->device->iorequest_cnt);
1419 * SCSI request completion path will do scsi_device_unbusy(),
1420 * bump busy counts. To bump the counters, we need to dance
1421 * with the locks as normal issue path does.
1423 sdev->device_busy++;
1424 spin_unlock(sdev->request_queue->queue_lock);
1425 spin_lock(shost->host_lock);
1426 shost->host_busy++;
1427 starget->target_busy++;
1428 spin_unlock(shost->host_lock);
1429 spin_lock(sdev->request_queue->queue_lock);
1431 blk_complete_request(req);
1434 static void scsi_softirq_done(struct request *rq)
1436 struct scsi_cmnd *cmd = rq->special;
1437 unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1438 int disposition;
1440 INIT_LIST_HEAD(&cmd->eh_entry);
1442 atomic_inc(&cmd->device->iodone_cnt);
1443 if (cmd->result)
1444 atomic_inc(&cmd->device->ioerr_cnt);
1446 disposition = scsi_decide_disposition(cmd);
1447 if (disposition != SUCCESS &&
1448 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1449 sdev_printk(KERN_ERR, cmd->device,
1450 "timing out command, waited %lus\n",
1451 wait_for/HZ);
1452 disposition = SUCCESS;
1455 scsi_log_completion(cmd, disposition);
1457 switch (disposition) {
1458 case SUCCESS:
1459 scsi_finish_command(cmd);
1460 break;
1461 case NEEDS_RETRY:
1462 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1463 break;
1464 case ADD_TO_MLQUEUE:
1465 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1466 break;
1467 default:
1468 if (!scsi_eh_scmd_add(cmd, 0))
1469 scsi_finish_command(cmd);
1474 * Function: scsi_request_fn()
1476 * Purpose: Main strategy routine for SCSI.
1478 * Arguments: q - Pointer to actual queue.
1480 * Returns: Nothing
1482 * Lock status: IO request lock assumed to be held when called.
1484 static void scsi_request_fn(struct request_queue *q)
1486 struct scsi_device *sdev = q->queuedata;
1487 struct Scsi_Host *shost;
1488 struct scsi_cmnd *cmd;
1489 struct request *req;
1491 if (!sdev) {
1492 printk("scsi: killing requests for dead queue\n");
1493 while ((req = blk_peek_request(q)) != NULL)
1494 scsi_kill_request(req, q);
1495 return;
1498 if(!get_device(&sdev->sdev_gendev))
1499 /* We must be tearing the block queue down already */
1500 return;
1503 * To start with, we keep looping until the queue is empty, or until
1504 * the host is no longer able to accept any more requests.
1506 shost = sdev->host;
1507 for (;;) {
1508 int rtn;
1510 * get next queueable request. We do this early to make sure
1511 * that the request is fully prepared even if we cannot
1512 * accept it.
1514 req = blk_peek_request(q);
1515 if (!req || !scsi_dev_queue_ready(q, sdev))
1516 break;
1518 if (unlikely(!scsi_device_online(sdev))) {
1519 sdev_printk(KERN_ERR, sdev,
1520 "rejecting I/O to offline device\n");
1521 scsi_kill_request(req, q);
1522 continue;
1527 * Remove the request from the request list.
1529 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1530 blk_start_request(req);
1531 sdev->device_busy++;
1533 spin_unlock(q->queue_lock);
1534 cmd = req->special;
1535 if (unlikely(cmd == NULL)) {
1536 printk(KERN_CRIT "impossible request in %s.\n"
1537 "please mail a stack trace to "
1538 "linux-scsi@vger.kernel.org\n",
1539 __func__);
1540 blk_dump_rq_flags(req, "foo");
1541 BUG();
1543 spin_lock(shost->host_lock);
1546 * We hit this when the driver is using a host wide
1547 * tag map. For device level tag maps the queue_depth check
1548 * in the device ready fn would prevent us from trying
1549 * to allocate a tag. Since the map is a shared host resource
1550 * we add the dev to the starved list so it eventually gets
1551 * a run when a tag is freed.
1553 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1554 if (list_empty(&sdev->starved_entry))
1555 list_add_tail(&sdev->starved_entry,
1556 &shost->starved_list);
1557 goto not_ready;
1560 if (!scsi_target_queue_ready(shost, sdev))
1561 goto not_ready;
1563 if (!scsi_host_queue_ready(q, shost, sdev))
1564 goto not_ready;
1566 scsi_target(sdev)->target_busy++;
1567 shost->host_busy++;
1570 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1571 * take the lock again.
1573 spin_unlock_irq(shost->host_lock);
1576 * Finally, initialize any error handling parameters, and set up
1577 * the timers for timeouts.
1579 scsi_init_cmd_errh(cmd);
1582 * Dispatch the command to the low-level driver.
1584 rtn = scsi_dispatch_cmd(cmd);
1585 spin_lock_irq(q->queue_lock);
1586 if (rtn)
1587 goto out_delay;
1590 goto out;
1592 not_ready:
1593 spin_unlock_irq(shost->host_lock);
1596 * lock q, handle tag, requeue req, and decrement device_busy. We
1597 * must return with queue_lock held.
1599 * Decrementing device_busy without checking it is OK, as all such
1600 * cases (host limits or settings) should run the queue at some
1601 * later time.
1603 spin_lock_irq(q->queue_lock);
1604 blk_requeue_request(q, req);
1605 sdev->device_busy--;
1606 out_delay:
1607 if (sdev->device_busy == 0)
1608 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1609 out:
1610 /* must be careful here...if we trigger the ->remove() function
1611 * we cannot be holding the q lock */
1612 spin_unlock_irq(q->queue_lock);
1613 put_device(&sdev->sdev_gendev);
1614 spin_lock_irq(q->queue_lock);
1617 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1619 struct device *host_dev;
1620 u64 bounce_limit = 0xffffffff;
1622 if (shost->unchecked_isa_dma)
1623 return BLK_BOUNCE_ISA;
1625 * Platforms with virtual-DMA translation
1626 * hardware have no practical limit.
1628 if (!PCI_DMA_BUS_IS_PHYS)
1629 return BLK_BOUNCE_ANY;
1631 host_dev = scsi_get_device(shost);
1632 if (host_dev && host_dev->dma_mask)
1633 bounce_limit = *host_dev->dma_mask;
1635 return bounce_limit;
1637 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1639 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1640 request_fn_proc *request_fn)
1642 struct request_queue *q;
1643 struct device *dev = shost->shost_gendev.parent;
1645 q = blk_init_queue(request_fn, NULL);
1646 if (!q)
1647 return NULL;
1650 * this limit is imposed by hardware restrictions
1652 blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1653 SCSI_MAX_SG_CHAIN_SEGMENTS));
1655 if (scsi_host_prot_dma(shost)) {
1656 shost->sg_prot_tablesize =
1657 min_not_zero(shost->sg_prot_tablesize,
1658 (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1659 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1660 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1663 blk_queue_max_hw_sectors(q, shost->max_sectors);
1664 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1665 blk_queue_segment_boundary(q, shost->dma_boundary);
1666 dma_set_seg_boundary(dev, shost->dma_boundary);
1668 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1670 if (!shost->use_clustering)
1671 q->limits.cluster = 0;
1674 * set a reasonable default alignment on word boundaries: the
1675 * host and device may alter it using
1676 * blk_queue_update_dma_alignment() later.
1678 blk_queue_dma_alignment(q, 0x03);
1680 return q;
1682 EXPORT_SYMBOL(__scsi_alloc_queue);
1684 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1686 struct request_queue *q;
1688 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1689 if (!q)
1690 return NULL;
1692 blk_queue_prep_rq(q, scsi_prep_fn);
1693 blk_queue_softirq_done(q, scsi_softirq_done);
1694 blk_queue_rq_timed_out(q, scsi_times_out);
1695 blk_queue_lld_busy(q, scsi_lld_busy);
1696 return q;
1699 void scsi_free_queue(struct request_queue *q)
1701 blk_cleanup_queue(q);
1705 * Function: scsi_block_requests()
1707 * Purpose: Utility function used by low-level drivers to prevent further
1708 * commands from being queued to the device.
1710 * Arguments: shost - Host in question
1712 * Returns: Nothing
1714 * Lock status: No locks are assumed held.
1716 * Notes: There is no timer nor any other means by which the requests
1717 * get unblocked other than the low-level driver calling
1718 * scsi_unblock_requests().
1720 void scsi_block_requests(struct Scsi_Host *shost)
1722 shost->host_self_blocked = 1;
1724 EXPORT_SYMBOL(scsi_block_requests);
1727 * Function: scsi_unblock_requests()
1729 * Purpose: Utility function used by low-level drivers to allow further
1730 * commands from being queued to the device.
1732 * Arguments: shost - Host in question
1734 * Returns: Nothing
1736 * Lock status: No locks are assumed held.
1738 * Notes: There is no timer nor any other means by which the requests
1739 * get unblocked other than the low-level driver calling
1740 * scsi_unblock_requests().
1742 * This is done as an API function so that changes to the
1743 * internals of the scsi mid-layer won't require wholesale
1744 * changes to drivers that use this feature.
1746 void scsi_unblock_requests(struct Scsi_Host *shost)
1748 shost->host_self_blocked = 0;
1749 scsi_run_host_queues(shost);
1751 EXPORT_SYMBOL(scsi_unblock_requests);
1753 int __init scsi_init_queue(void)
1755 int i;
1757 scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1758 sizeof(struct scsi_data_buffer),
1759 0, 0, NULL);
1760 if (!scsi_sdb_cache) {
1761 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1762 return -ENOMEM;
1765 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1766 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1767 int size = sgp->size * sizeof(struct scatterlist);
1769 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1770 SLAB_HWCACHE_ALIGN, NULL);
1771 if (!sgp->slab) {
1772 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1773 sgp->name);
1774 goto cleanup_sdb;
1777 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1778 sgp->slab);
1779 if (!sgp->pool) {
1780 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1781 sgp->name);
1782 goto cleanup_sdb;
1786 return 0;
1788 cleanup_sdb:
1789 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1790 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1791 if (sgp->pool)
1792 mempool_destroy(sgp->pool);
1793 if (sgp->slab)
1794 kmem_cache_destroy(sgp->slab);
1796 kmem_cache_destroy(scsi_sdb_cache);
1798 return -ENOMEM;
1801 void scsi_exit_queue(void)
1803 int i;
1805 kmem_cache_destroy(scsi_sdb_cache);
1807 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1808 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1809 mempool_destroy(sgp->pool);
1810 kmem_cache_destroy(sgp->slab);
1815 * scsi_mode_select - issue a mode select
1816 * @sdev: SCSI device to be queried
1817 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1818 * @sp: Save page bit (0 == don't save, 1 == save)
1819 * @modepage: mode page being requested
1820 * @buffer: request buffer (may not be smaller than eight bytes)
1821 * @len: length of request buffer.
1822 * @timeout: command timeout
1823 * @retries: number of retries before failing
1824 * @data: returns a structure abstracting the mode header data
1825 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1826 * must be SCSI_SENSE_BUFFERSIZE big.
1828 * Returns zero if successful; negative error number or scsi
1829 * status on error
1833 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1834 unsigned char *buffer, int len, int timeout, int retries,
1835 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1837 unsigned char cmd[10];
1838 unsigned char *real_buffer;
1839 int ret;
1841 memset(cmd, 0, sizeof(cmd));
1842 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1844 if (sdev->use_10_for_ms) {
1845 if (len > 65535)
1846 return -EINVAL;
1847 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1848 if (!real_buffer)
1849 return -ENOMEM;
1850 memcpy(real_buffer + 8, buffer, len);
1851 len += 8;
1852 real_buffer[0] = 0;
1853 real_buffer[1] = 0;
1854 real_buffer[2] = data->medium_type;
1855 real_buffer[3] = data->device_specific;
1856 real_buffer[4] = data->longlba ? 0x01 : 0;
1857 real_buffer[5] = 0;
1858 real_buffer[6] = data->block_descriptor_length >> 8;
1859 real_buffer[7] = data->block_descriptor_length;
1861 cmd[0] = MODE_SELECT_10;
1862 cmd[7] = len >> 8;
1863 cmd[8] = len;
1864 } else {
1865 if (len > 255 || data->block_descriptor_length > 255 ||
1866 data->longlba)
1867 return -EINVAL;
1869 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1870 if (!real_buffer)
1871 return -ENOMEM;
1872 memcpy(real_buffer + 4, buffer, len);
1873 len += 4;
1874 real_buffer[0] = 0;
1875 real_buffer[1] = data->medium_type;
1876 real_buffer[2] = data->device_specific;
1877 real_buffer[3] = data->block_descriptor_length;
1880 cmd[0] = MODE_SELECT;
1881 cmd[4] = len;
1884 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1885 sshdr, timeout, retries, NULL);
1886 kfree(real_buffer);
1887 return ret;
1889 EXPORT_SYMBOL_GPL(scsi_mode_select);
1892 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1893 * @sdev: SCSI device to be queried
1894 * @dbd: set if mode sense will allow block descriptors to be returned
1895 * @modepage: mode page being requested
1896 * @buffer: request buffer (may not be smaller than eight bytes)
1897 * @len: length of request buffer.
1898 * @timeout: command timeout
1899 * @retries: number of retries before failing
1900 * @data: returns a structure abstracting the mode header data
1901 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1902 * must be SCSI_SENSE_BUFFERSIZE big.
1904 * Returns zero if unsuccessful, or the header offset (either 4
1905 * or 8 depending on whether a six or ten byte command was
1906 * issued) if successful.
1909 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1910 unsigned char *buffer, int len, int timeout, int retries,
1911 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1913 unsigned char cmd[12];
1914 int use_10_for_ms;
1915 int header_length;
1916 int result;
1917 struct scsi_sense_hdr my_sshdr;
1919 memset(data, 0, sizeof(*data));
1920 memset(&cmd[0], 0, 12);
1921 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1922 cmd[2] = modepage;
1924 /* caller might not be interested in sense, but we need it */
1925 if (!sshdr)
1926 sshdr = &my_sshdr;
1928 retry:
1929 use_10_for_ms = sdev->use_10_for_ms;
1931 if (use_10_for_ms) {
1932 if (len < 8)
1933 len = 8;
1935 cmd[0] = MODE_SENSE_10;
1936 cmd[8] = len;
1937 header_length = 8;
1938 } else {
1939 if (len < 4)
1940 len = 4;
1942 cmd[0] = MODE_SENSE;
1943 cmd[4] = len;
1944 header_length = 4;
1947 memset(buffer, 0, len);
1949 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1950 sshdr, timeout, retries, NULL);
1952 /* This code looks awful: what it's doing is making sure an
1953 * ILLEGAL REQUEST sense return identifies the actual command
1954 * byte as the problem. MODE_SENSE commands can return
1955 * ILLEGAL REQUEST if the code page isn't supported */
1957 if (use_10_for_ms && !scsi_status_is_good(result) &&
1958 (driver_byte(result) & DRIVER_SENSE)) {
1959 if (scsi_sense_valid(sshdr)) {
1960 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1961 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1963 * Invalid command operation code
1965 sdev->use_10_for_ms = 0;
1966 goto retry;
1971 if(scsi_status_is_good(result)) {
1972 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1973 (modepage == 6 || modepage == 8))) {
1974 /* Initio breakage? */
1975 header_length = 0;
1976 data->length = 13;
1977 data->medium_type = 0;
1978 data->device_specific = 0;
1979 data->longlba = 0;
1980 data->block_descriptor_length = 0;
1981 } else if(use_10_for_ms) {
1982 data->length = buffer[0]*256 + buffer[1] + 2;
1983 data->medium_type = buffer[2];
1984 data->device_specific = buffer[3];
1985 data->longlba = buffer[4] & 0x01;
1986 data->block_descriptor_length = buffer[6]*256
1987 + buffer[7];
1988 } else {
1989 data->length = buffer[0] + 1;
1990 data->medium_type = buffer[1];
1991 data->device_specific = buffer[2];
1992 data->block_descriptor_length = buffer[3];
1994 data->header_length = header_length;
1997 return result;
1999 EXPORT_SYMBOL(scsi_mode_sense);
2002 * scsi_test_unit_ready - test if unit is ready
2003 * @sdev: scsi device to change the state of.
2004 * @timeout: command timeout
2005 * @retries: number of retries before failing
2006 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2007 * returning sense. Make sure that this is cleared before passing
2008 * in.
2010 * Returns zero if unsuccessful or an error if TUR failed. For
2011 * removable media, UNIT_ATTENTION sets ->changed flag.
2014 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2015 struct scsi_sense_hdr *sshdr_external)
2017 char cmd[] = {
2018 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2020 struct scsi_sense_hdr *sshdr;
2021 int result;
2023 if (!sshdr_external)
2024 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2025 else
2026 sshdr = sshdr_external;
2028 /* try to eat the UNIT_ATTENTION if there are enough retries */
2029 do {
2030 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2031 timeout, retries, NULL);
2032 if (sdev->removable && scsi_sense_valid(sshdr) &&
2033 sshdr->sense_key == UNIT_ATTENTION)
2034 sdev->changed = 1;
2035 } while (scsi_sense_valid(sshdr) &&
2036 sshdr->sense_key == UNIT_ATTENTION && --retries);
2038 if (!sshdr_external)
2039 kfree(sshdr);
2040 return result;
2042 EXPORT_SYMBOL(scsi_test_unit_ready);
2045 * scsi_device_set_state - Take the given device through the device state model.
2046 * @sdev: scsi device to change the state of.
2047 * @state: state to change to.
2049 * Returns zero if unsuccessful or an error if the requested
2050 * transition is illegal.
2053 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2055 enum scsi_device_state oldstate = sdev->sdev_state;
2057 if (state == oldstate)
2058 return 0;
2060 switch (state) {
2061 case SDEV_CREATED:
2062 switch (oldstate) {
2063 case SDEV_CREATED_BLOCK:
2064 break;
2065 default:
2066 goto illegal;
2068 break;
2070 case SDEV_RUNNING:
2071 switch (oldstate) {
2072 case SDEV_CREATED:
2073 case SDEV_OFFLINE:
2074 case SDEV_QUIESCE:
2075 case SDEV_BLOCK:
2076 break;
2077 default:
2078 goto illegal;
2080 break;
2082 case SDEV_QUIESCE:
2083 switch (oldstate) {
2084 case SDEV_RUNNING:
2085 case SDEV_OFFLINE:
2086 break;
2087 default:
2088 goto illegal;
2090 break;
2092 case SDEV_OFFLINE:
2093 switch (oldstate) {
2094 case SDEV_CREATED:
2095 case SDEV_RUNNING:
2096 case SDEV_QUIESCE:
2097 case SDEV_BLOCK:
2098 break;
2099 default:
2100 goto illegal;
2102 break;
2104 case SDEV_BLOCK:
2105 switch (oldstate) {
2106 case SDEV_RUNNING:
2107 case SDEV_CREATED_BLOCK:
2108 break;
2109 default:
2110 goto illegal;
2112 break;
2114 case SDEV_CREATED_BLOCK:
2115 switch (oldstate) {
2116 case SDEV_CREATED:
2117 break;
2118 default:
2119 goto illegal;
2121 break;
2123 case SDEV_CANCEL:
2124 switch (oldstate) {
2125 case SDEV_CREATED:
2126 case SDEV_RUNNING:
2127 case SDEV_QUIESCE:
2128 case SDEV_OFFLINE:
2129 case SDEV_BLOCK:
2130 break;
2131 default:
2132 goto illegal;
2134 break;
2136 case SDEV_DEL:
2137 switch (oldstate) {
2138 case SDEV_CREATED:
2139 case SDEV_RUNNING:
2140 case SDEV_OFFLINE:
2141 case SDEV_CANCEL:
2142 break;
2143 default:
2144 goto illegal;
2146 break;
2149 sdev->sdev_state = state;
2150 return 0;
2152 illegal:
2153 SCSI_LOG_ERROR_RECOVERY(1,
2154 sdev_printk(KERN_ERR, sdev,
2155 "Illegal state transition %s->%s\n",
2156 scsi_device_state_name(oldstate),
2157 scsi_device_state_name(state))
2159 return -EINVAL;
2161 EXPORT_SYMBOL(scsi_device_set_state);
2164 * sdev_evt_emit - emit a single SCSI device uevent
2165 * @sdev: associated SCSI device
2166 * @evt: event to emit
2168 * Send a single uevent (scsi_event) to the associated scsi_device.
2170 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2172 int idx = 0;
2173 char *envp[3];
2175 switch (evt->evt_type) {
2176 case SDEV_EVT_MEDIA_CHANGE:
2177 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2178 break;
2180 default:
2181 /* do nothing */
2182 break;
2185 envp[idx++] = NULL;
2187 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2191 * sdev_evt_thread - send a uevent for each scsi event
2192 * @work: work struct for scsi_device
2194 * Dispatch queued events to their associated scsi_device kobjects
2195 * as uevents.
2197 void scsi_evt_thread(struct work_struct *work)
2199 struct scsi_device *sdev;
2200 LIST_HEAD(event_list);
2202 sdev = container_of(work, struct scsi_device, event_work);
2204 while (1) {
2205 struct scsi_event *evt;
2206 struct list_head *this, *tmp;
2207 unsigned long flags;
2209 spin_lock_irqsave(&sdev->list_lock, flags);
2210 list_splice_init(&sdev->event_list, &event_list);
2211 spin_unlock_irqrestore(&sdev->list_lock, flags);
2213 if (list_empty(&event_list))
2214 break;
2216 list_for_each_safe(this, tmp, &event_list) {
2217 evt = list_entry(this, struct scsi_event, node);
2218 list_del(&evt->node);
2219 scsi_evt_emit(sdev, evt);
2220 kfree(evt);
2226 * sdev_evt_send - send asserted event to uevent thread
2227 * @sdev: scsi_device event occurred on
2228 * @evt: event to send
2230 * Assert scsi device event asynchronously.
2232 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2234 unsigned long flags;
2236 #if 0
2237 /* FIXME: currently this check eliminates all media change events
2238 * for polled devices. Need to update to discriminate between AN
2239 * and polled events */
2240 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2241 kfree(evt);
2242 return;
2244 #endif
2246 spin_lock_irqsave(&sdev->list_lock, flags);
2247 list_add_tail(&evt->node, &sdev->event_list);
2248 schedule_work(&sdev->event_work);
2249 spin_unlock_irqrestore(&sdev->list_lock, flags);
2251 EXPORT_SYMBOL_GPL(sdev_evt_send);
2254 * sdev_evt_alloc - allocate a new scsi event
2255 * @evt_type: type of event to allocate
2256 * @gfpflags: GFP flags for allocation
2258 * Allocates and returns a new scsi_event.
2260 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2261 gfp_t gfpflags)
2263 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2264 if (!evt)
2265 return NULL;
2267 evt->evt_type = evt_type;
2268 INIT_LIST_HEAD(&evt->node);
2270 /* evt_type-specific initialization, if any */
2271 switch (evt_type) {
2272 case SDEV_EVT_MEDIA_CHANGE:
2273 default:
2274 /* do nothing */
2275 break;
2278 return evt;
2280 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2283 * sdev_evt_send_simple - send asserted event to uevent thread
2284 * @sdev: scsi_device event occurred on
2285 * @evt_type: type of event to send
2286 * @gfpflags: GFP flags for allocation
2288 * Assert scsi device event asynchronously, given an event type.
2290 void sdev_evt_send_simple(struct scsi_device *sdev,
2291 enum scsi_device_event evt_type, gfp_t gfpflags)
2293 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2294 if (!evt) {
2295 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2296 evt_type);
2297 return;
2300 sdev_evt_send(sdev, evt);
2302 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2305 * scsi_device_quiesce - Block user issued commands.
2306 * @sdev: scsi device to quiesce.
2308 * This works by trying to transition to the SDEV_QUIESCE state
2309 * (which must be a legal transition). When the device is in this
2310 * state, only special requests will be accepted, all others will
2311 * be deferred. Since special requests may also be requeued requests,
2312 * a successful return doesn't guarantee the device will be
2313 * totally quiescent.
2315 * Must be called with user context, may sleep.
2317 * Returns zero if unsuccessful or an error if not.
2320 scsi_device_quiesce(struct scsi_device *sdev)
2322 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2323 if (err)
2324 return err;
2326 scsi_run_queue(sdev->request_queue);
2327 while (sdev->device_busy) {
2328 msleep_interruptible(200);
2329 scsi_run_queue(sdev->request_queue);
2331 return 0;
2333 EXPORT_SYMBOL(scsi_device_quiesce);
2336 * scsi_device_resume - Restart user issued commands to a quiesced device.
2337 * @sdev: scsi device to resume.
2339 * Moves the device from quiesced back to running and restarts the
2340 * queues.
2342 * Must be called with user context, may sleep.
2344 void
2345 scsi_device_resume(struct scsi_device *sdev)
2347 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2348 return;
2349 scsi_run_queue(sdev->request_queue);
2351 EXPORT_SYMBOL(scsi_device_resume);
2353 static void
2354 device_quiesce_fn(struct scsi_device *sdev, void *data)
2356 scsi_device_quiesce(sdev);
2359 void
2360 scsi_target_quiesce(struct scsi_target *starget)
2362 starget_for_each_device(starget, NULL, device_quiesce_fn);
2364 EXPORT_SYMBOL(scsi_target_quiesce);
2366 static void
2367 device_resume_fn(struct scsi_device *sdev, void *data)
2369 scsi_device_resume(sdev);
2372 void
2373 scsi_target_resume(struct scsi_target *starget)
2375 starget_for_each_device(starget, NULL, device_resume_fn);
2377 EXPORT_SYMBOL(scsi_target_resume);
2380 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2381 * @sdev: device to block
2383 * Block request made by scsi lld's to temporarily stop all
2384 * scsi commands on the specified device. Called from interrupt
2385 * or normal process context.
2387 * Returns zero if successful or error if not
2389 * Notes:
2390 * This routine transitions the device to the SDEV_BLOCK state
2391 * (which must be a legal transition). When the device is in this
2392 * state, all commands are deferred until the scsi lld reenables
2393 * the device with scsi_device_unblock or device_block_tmo fires.
2394 * This routine assumes the host_lock is held on entry.
2397 scsi_internal_device_block(struct scsi_device *sdev)
2399 struct request_queue *q = sdev->request_queue;
2400 unsigned long flags;
2401 int err = 0;
2403 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2404 if (err) {
2405 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2407 if (err)
2408 return err;
2412 * The device has transitioned to SDEV_BLOCK. Stop the
2413 * block layer from calling the midlayer with this device's
2414 * request queue.
2416 spin_lock_irqsave(q->queue_lock, flags);
2417 blk_stop_queue(q);
2418 spin_unlock_irqrestore(q->queue_lock, flags);
2420 return 0;
2422 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2425 * scsi_internal_device_unblock - resume a device after a block request
2426 * @sdev: device to resume
2428 * Called by scsi lld's or the midlayer to restart the device queue
2429 * for the previously suspended scsi device. Called from interrupt or
2430 * normal process context.
2432 * Returns zero if successful or error if not.
2434 * Notes:
2435 * This routine transitions the device to the SDEV_RUNNING state
2436 * (which must be a legal transition) allowing the midlayer to
2437 * goose the queue for this device. This routine assumes the
2438 * host_lock is held upon entry.
2441 scsi_internal_device_unblock(struct scsi_device *sdev)
2443 struct request_queue *q = sdev->request_queue;
2444 unsigned long flags;
2447 * Try to transition the scsi device to SDEV_RUNNING
2448 * and goose the device queue if successful.
2450 if (sdev->sdev_state == SDEV_BLOCK)
2451 sdev->sdev_state = SDEV_RUNNING;
2452 else if (sdev->sdev_state == SDEV_CREATED_BLOCK)
2453 sdev->sdev_state = SDEV_CREATED;
2454 else if (sdev->sdev_state != SDEV_CANCEL &&
2455 sdev->sdev_state != SDEV_OFFLINE)
2456 return -EINVAL;
2458 spin_lock_irqsave(q->queue_lock, flags);
2459 blk_start_queue(q);
2460 spin_unlock_irqrestore(q->queue_lock, flags);
2462 return 0;
2464 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2466 static void
2467 device_block(struct scsi_device *sdev, void *data)
2469 scsi_internal_device_block(sdev);
2472 static int
2473 target_block(struct device *dev, void *data)
2475 if (scsi_is_target_device(dev))
2476 starget_for_each_device(to_scsi_target(dev), NULL,
2477 device_block);
2478 return 0;
2481 void
2482 scsi_target_block(struct device *dev)
2484 if (scsi_is_target_device(dev))
2485 starget_for_each_device(to_scsi_target(dev), NULL,
2486 device_block);
2487 else
2488 device_for_each_child(dev, NULL, target_block);
2490 EXPORT_SYMBOL_GPL(scsi_target_block);
2492 static void
2493 device_unblock(struct scsi_device *sdev, void *data)
2495 scsi_internal_device_unblock(sdev);
2498 static int
2499 target_unblock(struct device *dev, void *data)
2501 if (scsi_is_target_device(dev))
2502 starget_for_each_device(to_scsi_target(dev), NULL,
2503 device_unblock);
2504 return 0;
2507 void
2508 scsi_target_unblock(struct device *dev)
2510 if (scsi_is_target_device(dev))
2511 starget_for_each_device(to_scsi_target(dev), NULL,
2512 device_unblock);
2513 else
2514 device_for_each_child(dev, NULL, target_unblock);
2516 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2519 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2520 * @sgl: scatter-gather list
2521 * @sg_count: number of segments in sg
2522 * @offset: offset in bytes into sg, on return offset into the mapped area
2523 * @len: bytes to map, on return number of bytes mapped
2525 * Returns virtual address of the start of the mapped page
2527 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2528 size_t *offset, size_t *len)
2530 int i;
2531 size_t sg_len = 0, len_complete = 0;
2532 struct scatterlist *sg;
2533 struct page *page;
2535 WARN_ON(!irqs_disabled());
2537 for_each_sg(sgl, sg, sg_count, i) {
2538 len_complete = sg_len; /* Complete sg-entries */
2539 sg_len += sg->length;
2540 if (sg_len > *offset)
2541 break;
2544 if (unlikely(i == sg_count)) {
2545 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2546 "elements %d\n",
2547 __func__, sg_len, *offset, sg_count);
2548 WARN_ON(1);
2549 return NULL;
2552 /* Offset starting from the beginning of first page in this sg-entry */
2553 *offset = *offset - len_complete + sg->offset;
2555 /* Assumption: contiguous pages can be accessed as "page + i" */
2556 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2557 *offset &= ~PAGE_MASK;
2559 /* Bytes in this sg-entry from *offset to the end of the page */
2560 sg_len = PAGE_SIZE - *offset;
2561 if (*len > sg_len)
2562 *len = sg_len;
2564 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2566 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2569 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2570 * @virt: virtual address to be unmapped
2572 void scsi_kunmap_atomic_sg(void *virt)
2574 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2576 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);