[SCSI] libiscsi: rename iscsi_cmd_task to iscsi_task
[linux-2.6/kvm.git] / drivers / scsi / scsi_lib.c
blob033c58a65f50d6c4b07ce94278178b316a9ac7f0
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 static struct kmem_cache *scsi_bidi_sdb_cache;
70 static void scsi_run_queue(struct request_queue *q);
73 * Function: scsi_unprep_request()
75 * Purpose: Remove all preparation done for a request, including its
76 * associated scsi_cmnd, so that it can be requeued.
78 * Arguments: req - request to unprepare
80 * Lock status: Assumed that no locks are held upon entry.
82 * Returns: Nothing.
84 static void scsi_unprep_request(struct request *req)
86 struct scsi_cmnd *cmd = req->special;
88 req->cmd_flags &= ~REQ_DONTPREP;
89 req->special = NULL;
91 scsi_put_command(cmd);
95 * Function: scsi_queue_insert()
97 * Purpose: Insert a command in the midlevel queue.
99 * Arguments: cmd - command that we are adding to queue.
100 * reason - why we are inserting command to queue.
102 * Lock status: Assumed that lock is not held upon entry.
104 * Returns: Nothing.
106 * Notes: We do this for one of two cases. Either the host is busy
107 * and it cannot accept any more commands for the time being,
108 * or the device returned QUEUE_FULL and can accept no more
109 * commands.
110 * Notes: This could be called either from an interrupt context or a
111 * normal process context.
113 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
115 struct Scsi_Host *host = cmd->device->host;
116 struct scsi_device *device = cmd->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 if (reason == SCSI_MLQUEUE_HOST_BUSY)
137 host->host_blocked = host->max_host_blocked;
138 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
139 device->device_blocked = device->max_device_blocked;
142 * Decrement the counters, since these commands are no longer
143 * active on the host/device.
145 scsi_device_unbusy(device);
148 * Requeue this command. It will go before all other commands
149 * that are already in the queue.
151 * NOTE: there is magic here about the way the queue is plugged if
152 * we have no outstanding commands.
154 * Although we *don't* plug the queue, we call the request
155 * function. The SCSI request function detects the blocked condition
156 * and plugs the queue appropriately.
158 spin_lock_irqsave(q->queue_lock, flags);
159 blk_requeue_request(q, cmd->request);
160 spin_unlock_irqrestore(q->queue_lock, flags);
162 scsi_run_queue(q);
164 return 0;
168 * scsi_execute - insert request and wait for the result
169 * @sdev: scsi device
170 * @cmd: scsi command
171 * @data_direction: data direction
172 * @buffer: data buffer
173 * @bufflen: len of buffer
174 * @sense: optional sense buffer
175 * @timeout: request timeout in seconds
176 * @retries: number of times to retry request
177 * @flags: or into request flags;
179 * returns the req->errors value which is the scsi_cmnd result
180 * field.
182 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
183 int data_direction, void *buffer, unsigned bufflen,
184 unsigned char *sense, int timeout, int retries, int flags)
186 struct request *req;
187 int write = (data_direction == DMA_TO_DEVICE);
188 int ret = DRIVER_ERROR << 24;
190 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
192 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
193 buffer, bufflen, __GFP_WAIT))
194 goto out;
196 req->cmd_len = COMMAND_SIZE(cmd[0]);
197 memcpy(req->cmd, cmd, req->cmd_len);
198 req->sense = sense;
199 req->sense_len = 0;
200 req->retries = retries;
201 req->timeout = timeout;
202 req->cmd_type = REQ_TYPE_BLOCK_PC;
203 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
206 * head injection *required* here otherwise quiesce won't work
208 blk_execute_rq(req->q, NULL, req, 1);
210 ret = req->errors;
211 out:
212 blk_put_request(req);
214 return ret;
216 EXPORT_SYMBOL(scsi_execute);
219 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
220 int data_direction, void *buffer, unsigned bufflen,
221 struct scsi_sense_hdr *sshdr, int timeout, int retries)
223 char *sense = NULL;
224 int result;
226 if (sshdr) {
227 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
228 if (!sense)
229 return DRIVER_ERROR << 24;
231 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
232 sense, timeout, retries, 0);
233 if (sshdr)
234 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
236 kfree(sense);
237 return result;
239 EXPORT_SYMBOL(scsi_execute_req);
241 struct scsi_io_context {
242 void *data;
243 void (*done)(void *data, char *sense, int result, int resid);
244 char sense[SCSI_SENSE_BUFFERSIZE];
247 static struct kmem_cache *scsi_io_context_cache;
249 static void scsi_end_async(struct request *req, int uptodate)
251 struct scsi_io_context *sioc = req->end_io_data;
253 if (sioc->done)
254 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
256 kmem_cache_free(scsi_io_context_cache, sioc);
257 __blk_put_request(req->q, req);
260 static int scsi_merge_bio(struct request *rq, struct bio *bio)
262 struct request_queue *q = rq->q;
264 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
265 if (rq_data_dir(rq) == WRITE)
266 bio->bi_rw |= (1 << BIO_RW);
267 blk_queue_bounce(q, &bio);
269 return blk_rq_append_bio(q, rq, bio);
272 static void scsi_bi_endio(struct bio *bio, int error)
274 bio_put(bio);
278 * scsi_req_map_sg - map a scatterlist into a request
279 * @rq: request to fill
280 * @sgl: scatterlist
281 * @nsegs: number of elements
282 * @bufflen: len of buffer
283 * @gfp: memory allocation flags
285 * scsi_req_map_sg maps a scatterlist into a request so that the
286 * request can be sent to the block layer. We do not trust the scatterlist
287 * sent to use, as some ULDs use that struct to only organize the pages.
289 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
290 int nsegs, unsigned bufflen, gfp_t gfp)
292 struct request_queue *q = rq->q;
293 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
294 unsigned int data_len = bufflen, len, bytes, off;
295 struct scatterlist *sg;
296 struct page *page;
297 struct bio *bio = NULL;
298 int i, err, nr_vecs = 0;
300 for_each_sg(sgl, sg, nsegs, i) {
301 page = sg_page(sg);
302 off = sg->offset;
303 len = sg->length;
305 while (len > 0 && data_len > 0) {
307 * sg sends a scatterlist that is larger than
308 * the data_len it wants transferred for certain
309 * IO sizes
311 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
312 bytes = min(bytes, data_len);
314 if (!bio) {
315 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
316 nr_pages -= nr_vecs;
318 bio = bio_alloc(gfp, nr_vecs);
319 if (!bio) {
320 err = -ENOMEM;
321 goto free_bios;
323 bio->bi_end_io = scsi_bi_endio;
326 if (bio_add_pc_page(q, bio, page, bytes, off) !=
327 bytes) {
328 bio_put(bio);
329 err = -EINVAL;
330 goto free_bios;
333 if (bio->bi_vcnt >= nr_vecs) {
334 err = scsi_merge_bio(rq, bio);
335 if (err) {
336 bio_endio(bio, 0);
337 goto free_bios;
339 bio = NULL;
342 page++;
343 len -= bytes;
344 data_len -=bytes;
345 off = 0;
349 rq->buffer = rq->data = NULL;
350 rq->data_len = bufflen;
351 return 0;
353 free_bios:
354 while ((bio = rq->bio) != NULL) {
355 rq->bio = bio->bi_next;
357 * call endio instead of bio_put incase it was bounced
359 bio_endio(bio, 0);
362 return err;
366 * scsi_execute_async - insert request
367 * @sdev: scsi device
368 * @cmd: scsi command
369 * @cmd_len: length of scsi cdb
370 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
371 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
372 * @bufflen: len of buffer
373 * @use_sg: if buffer is a scatterlist this is the number of elements
374 * @timeout: request timeout in seconds
375 * @retries: number of times to retry request
376 * @privdata: data passed to done()
377 * @done: callback function when done
378 * @gfp: memory allocation flags
380 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
381 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
382 int use_sg, int timeout, int retries, void *privdata,
383 void (*done)(void *, char *, int, int), gfp_t gfp)
385 struct request *req;
386 struct scsi_io_context *sioc;
387 int err = 0;
388 int write = (data_direction == DMA_TO_DEVICE);
390 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
391 if (!sioc)
392 return DRIVER_ERROR << 24;
394 req = blk_get_request(sdev->request_queue, write, gfp);
395 if (!req)
396 goto free_sense;
397 req->cmd_type = REQ_TYPE_BLOCK_PC;
398 req->cmd_flags |= REQ_QUIET;
400 if (use_sg)
401 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
402 else if (bufflen)
403 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
405 if (err)
406 goto free_req;
408 req->cmd_len = cmd_len;
409 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
410 memcpy(req->cmd, cmd, req->cmd_len);
411 req->sense = sioc->sense;
412 req->sense_len = 0;
413 req->timeout = timeout;
414 req->retries = retries;
415 req->end_io_data = sioc;
417 sioc->data = privdata;
418 sioc->done = done;
420 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
421 return 0;
423 free_req:
424 blk_put_request(req);
425 free_sense:
426 kmem_cache_free(scsi_io_context_cache, sioc);
427 return DRIVER_ERROR << 24;
429 EXPORT_SYMBOL_GPL(scsi_execute_async);
432 * Function: scsi_init_cmd_errh()
434 * Purpose: Initialize cmd fields related to error handling.
436 * Arguments: cmd - command that is ready to be queued.
438 * Notes: This function has the job of initializing a number of
439 * fields related to error handling. Typically this will
440 * be called once for each command, as required.
442 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
444 cmd->serial_number = 0;
445 scsi_set_resid(cmd, 0);
446 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
447 if (cmd->cmd_len == 0)
448 cmd->cmd_len = scsi_command_size(cmd->cmnd);
451 void scsi_device_unbusy(struct scsi_device *sdev)
453 struct Scsi_Host *shost = sdev->host;
454 unsigned long flags;
456 spin_lock_irqsave(shost->host_lock, flags);
457 shost->host_busy--;
458 if (unlikely(scsi_host_in_recovery(shost) &&
459 (shost->host_failed || shost->host_eh_scheduled)))
460 scsi_eh_wakeup(shost);
461 spin_unlock(shost->host_lock);
462 spin_lock(sdev->request_queue->queue_lock);
463 sdev->device_busy--;
464 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
468 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
469 * and call blk_run_queue for all the scsi_devices on the target -
470 * including current_sdev first.
472 * Called with *no* scsi locks held.
474 static void scsi_single_lun_run(struct scsi_device *current_sdev)
476 struct Scsi_Host *shost = current_sdev->host;
477 struct scsi_device *sdev, *tmp;
478 struct scsi_target *starget = scsi_target(current_sdev);
479 unsigned long flags;
481 spin_lock_irqsave(shost->host_lock, flags);
482 starget->starget_sdev_user = NULL;
483 spin_unlock_irqrestore(shost->host_lock, flags);
486 * Call blk_run_queue for all LUNs on the target, starting with
487 * current_sdev. We race with others (to set starget_sdev_user),
488 * but in most cases, we will be first. Ideally, each LU on the
489 * target would get some limited time or requests on the target.
491 blk_run_queue(current_sdev->request_queue);
493 spin_lock_irqsave(shost->host_lock, flags);
494 if (starget->starget_sdev_user)
495 goto out;
496 list_for_each_entry_safe(sdev, tmp, &starget->devices,
497 same_target_siblings) {
498 if (sdev == current_sdev)
499 continue;
500 if (scsi_device_get(sdev))
501 continue;
503 spin_unlock_irqrestore(shost->host_lock, flags);
504 blk_run_queue(sdev->request_queue);
505 spin_lock_irqsave(shost->host_lock, flags);
507 scsi_device_put(sdev);
509 out:
510 spin_unlock_irqrestore(shost->host_lock, flags);
514 * Function: scsi_run_queue()
516 * Purpose: Select a proper request queue to serve next
518 * Arguments: q - last request's queue
520 * Returns: Nothing
522 * Notes: The previous command was completely finished, start
523 * a new one if possible.
525 static void scsi_run_queue(struct request_queue *q)
527 struct scsi_device *sdev = q->queuedata;
528 struct Scsi_Host *shost = sdev->host;
529 unsigned long flags;
531 if (scsi_target(sdev)->single_lun)
532 scsi_single_lun_run(sdev);
534 spin_lock_irqsave(shost->host_lock, flags);
535 while (!list_empty(&shost->starved_list) &&
536 !shost->host_blocked && !shost->host_self_blocked &&
537 !((shost->can_queue > 0) &&
538 (shost->host_busy >= shost->can_queue))) {
540 int flagset;
543 * As long as shost is accepting commands and we have
544 * starved queues, call blk_run_queue. scsi_request_fn
545 * drops the queue_lock and can add us back to the
546 * starved_list.
548 * host_lock protects the starved_list and starved_entry.
549 * scsi_request_fn must get the host_lock before checking
550 * or modifying starved_list or starved_entry.
552 sdev = list_entry(shost->starved_list.next,
553 struct scsi_device, starved_entry);
554 list_del_init(&sdev->starved_entry);
555 spin_unlock(shost->host_lock);
557 spin_lock(sdev->request_queue->queue_lock);
558 flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
559 !test_bit(QUEUE_FLAG_REENTER,
560 &sdev->request_queue->queue_flags);
561 if (flagset)
562 queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
563 __blk_run_queue(sdev->request_queue);
564 if (flagset)
565 queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
566 spin_unlock(sdev->request_queue->queue_lock);
568 spin_lock(shost->host_lock);
569 if (unlikely(!list_empty(&sdev->starved_entry)))
571 * sdev lost a race, and was put back on the
572 * starved list. This is unlikely but without this
573 * in theory we could loop forever.
575 break;
577 spin_unlock_irqrestore(shost->host_lock, flags);
579 blk_run_queue(q);
583 * Function: scsi_requeue_command()
585 * Purpose: Handle post-processing of completed commands.
587 * Arguments: q - queue to operate on
588 * cmd - command that may need to be requeued.
590 * Returns: Nothing
592 * Notes: After command completion, there may be blocks left
593 * over which weren't finished by the previous command
594 * this can be for a number of reasons - the main one is
595 * I/O errors in the middle of the request, in which case
596 * we need to request the blocks that come after the bad
597 * sector.
598 * Notes: Upon return, cmd is a stale pointer.
600 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
602 struct request *req = cmd->request;
603 unsigned long flags;
605 scsi_unprep_request(req);
606 spin_lock_irqsave(q->queue_lock, flags);
607 blk_requeue_request(q, req);
608 spin_unlock_irqrestore(q->queue_lock, flags);
610 scsi_run_queue(q);
613 void scsi_next_command(struct scsi_cmnd *cmd)
615 struct scsi_device *sdev = cmd->device;
616 struct request_queue *q = sdev->request_queue;
618 /* need to hold a reference on the device before we let go of the cmd */
619 get_device(&sdev->sdev_gendev);
621 scsi_put_command(cmd);
622 scsi_run_queue(q);
624 /* ok to remove device now */
625 put_device(&sdev->sdev_gendev);
628 void scsi_run_host_queues(struct Scsi_Host *shost)
630 struct scsi_device *sdev;
632 shost_for_each_device(sdev, shost)
633 scsi_run_queue(sdev->request_queue);
637 * Function: scsi_end_request()
639 * Purpose: Post-processing of completed commands (usually invoked at end
640 * of upper level post-processing and scsi_io_completion).
642 * Arguments: cmd - command that is complete.
643 * error - 0 if I/O indicates success, < 0 for I/O error.
644 * bytes - number of bytes of completed I/O
645 * requeue - indicates whether we should requeue leftovers.
647 * Lock status: Assumed that lock is not held upon entry.
649 * Returns: cmd if requeue required, NULL otherwise.
651 * Notes: This is called for block device requests in order to
652 * mark some number of sectors as complete.
654 * We are guaranteeing that the request queue will be goosed
655 * at some point during this call.
656 * Notes: If cmd was requeued, upon return it will be a stale pointer.
658 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
659 int bytes, int requeue)
661 struct request_queue *q = cmd->device->request_queue;
662 struct request *req = cmd->request;
665 * If there are blocks left over at the end, set up the command
666 * to queue the remainder of them.
668 if (blk_end_request(req, error, bytes)) {
669 int leftover = (req->hard_nr_sectors << 9);
671 if (blk_pc_request(req))
672 leftover = req->data_len;
674 /* kill remainder if no retrys */
675 if (error && blk_noretry_request(req))
676 blk_end_request(req, error, leftover);
677 else {
678 if (requeue) {
680 * Bleah. Leftovers again. Stick the
681 * leftovers in the front of the
682 * queue, and goose the queue again.
684 scsi_requeue_command(q, cmd);
685 cmd = NULL;
687 return cmd;
692 * This will goose the queue request function at the end, so we don't
693 * need to worry about launching another command.
695 scsi_next_command(cmd);
696 return NULL;
699 static inline unsigned int scsi_sgtable_index(unsigned short nents)
701 unsigned int index;
703 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
705 if (nents <= 8)
706 index = 0;
707 else
708 index = get_count_order(nents) - 3;
710 return index;
713 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
715 struct scsi_host_sg_pool *sgp;
717 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
718 mempool_free(sgl, sgp->pool);
721 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
723 struct scsi_host_sg_pool *sgp;
725 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
726 return mempool_alloc(sgp->pool, gfp_mask);
729 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
730 gfp_t gfp_mask)
732 int ret;
734 BUG_ON(!nents);
736 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
737 gfp_mask, scsi_sg_alloc);
738 if (unlikely(ret))
739 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
740 scsi_sg_free);
742 return ret;
745 static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
747 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
751 * Function: scsi_release_buffers()
753 * Purpose: Completion processing for block device I/O requests.
755 * Arguments: cmd - command that we are bailing.
757 * Lock status: Assumed that no lock is held upon entry.
759 * Returns: Nothing
761 * Notes: In the event that an upper level driver rejects a
762 * command, we must release resources allocated during
763 * the __init_io() function. Primarily this would involve
764 * the scatter-gather table, and potentially any bounce
765 * buffers.
767 void scsi_release_buffers(struct scsi_cmnd *cmd)
769 if (cmd->sdb.table.nents)
770 scsi_free_sgtable(&cmd->sdb);
772 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
774 if (scsi_bidi_cmnd(cmd)) {
775 struct scsi_data_buffer *bidi_sdb =
776 cmd->request->next_rq->special;
777 scsi_free_sgtable(bidi_sdb);
778 kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb);
779 cmd->request->next_rq->special = NULL;
782 EXPORT_SYMBOL(scsi_release_buffers);
785 * Bidi commands Must be complete as a whole, both sides at once.
786 * If part of the bytes were written and lld returned
787 * scsi_in()->resid and/or scsi_out()->resid this information will be left
788 * in req->data_len and req->next_rq->data_len. The upper-layer driver can
789 * decide what to do with this information.
791 static void scsi_end_bidi_request(struct scsi_cmnd *cmd)
793 struct request *req = cmd->request;
794 unsigned int dlen = req->data_len;
795 unsigned int next_dlen = req->next_rq->data_len;
797 req->data_len = scsi_out(cmd)->resid;
798 req->next_rq->data_len = scsi_in(cmd)->resid;
800 /* The req and req->next_rq have not been completed */
801 BUG_ON(blk_end_bidi_request(req, 0, dlen, next_dlen));
803 scsi_release_buffers(cmd);
806 * This will goose the queue request function at the end, so we don't
807 * need to worry about launching another command.
809 scsi_next_command(cmd);
813 * Function: scsi_io_completion()
815 * Purpose: Completion processing for block device I/O requests.
817 * Arguments: cmd - command that is finished.
819 * Lock status: Assumed that no lock is held upon entry.
821 * Returns: Nothing
823 * Notes: This function is matched in terms of capabilities to
824 * the function that created the scatter-gather list.
825 * In other words, if there are no bounce buffers
826 * (the normal case for most drivers), we don't need
827 * the logic to deal with cleaning up afterwards.
829 * We must do one of several things here:
831 * a) Call scsi_end_request. This will finish off the
832 * specified number of sectors. If we are done, the
833 * command block will be released, and the queue
834 * function will be goosed. If we are not done, then
835 * scsi_end_request will directly goose the queue.
837 * b) We can just use scsi_requeue_command() here. This would
838 * be used if we just wanted to retry, for example.
840 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
842 int result = cmd->result;
843 int this_count = scsi_bufflen(cmd);
844 struct request_queue *q = cmd->device->request_queue;
845 struct request *req = cmd->request;
846 int error = 0;
847 struct scsi_sense_hdr sshdr;
848 int sense_valid = 0;
849 int sense_deferred = 0;
851 if (result) {
852 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
853 if (sense_valid)
854 sense_deferred = scsi_sense_is_deferred(&sshdr);
857 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
858 req->errors = result;
859 if (result) {
860 if (sense_valid && req->sense) {
862 * SG_IO wants current and deferred errors
864 int len = 8 + cmd->sense_buffer[7];
866 if (len > SCSI_SENSE_BUFFERSIZE)
867 len = SCSI_SENSE_BUFFERSIZE;
868 memcpy(req->sense, cmd->sense_buffer, len);
869 req->sense_len = len;
871 if (!sense_deferred)
872 error = -EIO;
874 if (scsi_bidi_cmnd(cmd)) {
875 /* will also release_buffers */
876 scsi_end_bidi_request(cmd);
877 return;
879 req->data_len = scsi_get_resid(cmd);
882 BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */
883 scsi_release_buffers(cmd);
886 * Next deal with any sectors which we were able to correctly
887 * handle.
889 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
890 "%d bytes done.\n",
891 req->nr_sectors, good_bytes));
893 /* A number of bytes were successfully read. If there
894 * are leftovers and there is some kind of error
895 * (result != 0), retry the rest.
897 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
898 return;
900 /* good_bytes = 0, or (inclusive) there were leftovers and
901 * result = 0, so scsi_end_request couldn't retry.
903 if (sense_valid && !sense_deferred) {
904 switch (sshdr.sense_key) {
905 case UNIT_ATTENTION:
906 if (cmd->device->removable) {
907 /* Detected disc change. Set a bit
908 * and quietly refuse further access.
910 cmd->device->changed = 1;
911 scsi_end_request(cmd, -EIO, this_count, 1);
912 return;
913 } else {
914 /* Must have been a power glitch, or a
915 * bus reset. Could not have been a
916 * media change, so we just retry the
917 * request and see what happens.
919 scsi_requeue_command(q, cmd);
920 return;
922 break;
923 case ILLEGAL_REQUEST:
924 /* If we had an ILLEGAL REQUEST returned, then
925 * we may have performed an unsupported
926 * command. The only thing this should be
927 * would be a ten byte read where only a six
928 * byte read was supported. Also, on a system
929 * where READ CAPACITY failed, we may have
930 * read past the end of the disk.
932 if ((cmd->device->use_10_for_rw &&
933 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
934 (cmd->cmnd[0] == READ_10 ||
935 cmd->cmnd[0] == WRITE_10)) {
936 cmd->device->use_10_for_rw = 0;
937 /* This will cause a retry with a
938 * 6-byte command.
940 scsi_requeue_command(q, cmd);
941 return;
942 } else {
943 scsi_end_request(cmd, -EIO, this_count, 1);
944 return;
946 break;
947 case NOT_READY:
948 /* If the device is in the process of becoming
949 * ready, or has a temporary blockage, retry.
951 if (sshdr.asc == 0x04) {
952 switch (sshdr.ascq) {
953 case 0x01: /* becoming ready */
954 case 0x04: /* format in progress */
955 case 0x05: /* rebuild in progress */
956 case 0x06: /* recalculation in progress */
957 case 0x07: /* operation in progress */
958 case 0x08: /* Long write in progress */
959 case 0x09: /* self test in progress */
960 scsi_requeue_command(q, cmd);
961 return;
962 default:
963 break;
966 if (!(req->cmd_flags & REQ_QUIET))
967 scsi_cmd_print_sense_hdr(cmd,
968 "Device not ready",
969 &sshdr);
971 scsi_end_request(cmd, -EIO, this_count, 1);
972 return;
973 case VOLUME_OVERFLOW:
974 if (!(req->cmd_flags & REQ_QUIET)) {
975 scmd_printk(KERN_INFO, cmd,
976 "Volume overflow, CDB: ");
977 __scsi_print_command(cmd->cmnd);
978 scsi_print_sense("", cmd);
980 /* See SSC3rXX or current. */
981 scsi_end_request(cmd, -EIO, this_count, 1);
982 return;
983 default:
984 break;
987 if (host_byte(result) == DID_RESET) {
988 /* Third party bus reset or reset for error recovery
989 * reasons. Just retry the request and see what
990 * happens.
992 scsi_requeue_command(q, cmd);
993 return;
995 if (result) {
996 if (!(req->cmd_flags & REQ_QUIET)) {
997 scsi_print_result(cmd);
998 if (driver_byte(result) & DRIVER_SENSE)
999 scsi_print_sense("", cmd);
1002 scsi_end_request(cmd, -EIO, this_count, !result);
1005 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
1006 gfp_t gfp_mask)
1008 int count;
1011 * If sg table allocation fails, requeue request later.
1013 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
1014 gfp_mask))) {
1015 return BLKPREP_DEFER;
1018 req->buffer = NULL;
1021 * Next, walk the list, and fill in the addresses and sizes of
1022 * each segment.
1024 count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1025 BUG_ON(count > sdb->table.nents);
1026 sdb->table.nents = count;
1027 if (blk_pc_request(req))
1028 sdb->length = req->data_len;
1029 else
1030 sdb->length = req->nr_sectors << 9;
1031 return BLKPREP_OK;
1035 * Function: scsi_init_io()
1037 * Purpose: SCSI I/O initialize function.
1039 * Arguments: cmd - Command descriptor we wish to initialize
1041 * Returns: 0 on success
1042 * BLKPREP_DEFER if the failure is retryable
1043 * BLKPREP_KILL if the failure is fatal
1045 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1047 int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
1048 if (error)
1049 goto err_exit;
1051 if (blk_bidi_rq(cmd->request)) {
1052 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1053 scsi_bidi_sdb_cache, GFP_ATOMIC);
1054 if (!bidi_sdb) {
1055 error = BLKPREP_DEFER;
1056 goto err_exit;
1059 cmd->request->next_rq->special = bidi_sdb;
1060 error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
1061 GFP_ATOMIC);
1062 if (error)
1063 goto err_exit;
1066 return BLKPREP_OK ;
1068 err_exit:
1069 scsi_release_buffers(cmd);
1070 if (error == BLKPREP_KILL)
1071 scsi_put_command(cmd);
1072 else /* BLKPREP_DEFER */
1073 scsi_unprep_request(cmd->request);
1075 return error;
1077 EXPORT_SYMBOL(scsi_init_io);
1079 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1080 struct request *req)
1082 struct scsi_cmnd *cmd;
1084 if (!req->special) {
1085 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1086 if (unlikely(!cmd))
1087 return NULL;
1088 req->special = cmd;
1089 } else {
1090 cmd = req->special;
1093 /* pull a tag out of the request if we have one */
1094 cmd->tag = req->tag;
1095 cmd->request = req;
1097 cmd->cmnd = req->cmd;
1099 return cmd;
1102 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1104 struct scsi_cmnd *cmd;
1105 int ret = scsi_prep_state_check(sdev, req);
1107 if (ret != BLKPREP_OK)
1108 return ret;
1110 cmd = scsi_get_cmd_from_req(sdev, req);
1111 if (unlikely(!cmd))
1112 return BLKPREP_DEFER;
1115 * BLOCK_PC requests may transfer data, in which case they must
1116 * a bio attached to them. Or they might contain a SCSI command
1117 * that does not transfer data, in which case they may optionally
1118 * submit a request without an attached bio.
1120 if (req->bio) {
1121 int ret;
1123 BUG_ON(!req->nr_phys_segments);
1125 ret = scsi_init_io(cmd, GFP_ATOMIC);
1126 if (unlikely(ret))
1127 return ret;
1128 } else {
1129 BUG_ON(req->data_len);
1130 BUG_ON(req->data);
1132 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1133 req->buffer = NULL;
1136 cmd->cmd_len = req->cmd_len;
1137 if (!req->data_len)
1138 cmd->sc_data_direction = DMA_NONE;
1139 else if (rq_data_dir(req) == WRITE)
1140 cmd->sc_data_direction = DMA_TO_DEVICE;
1141 else
1142 cmd->sc_data_direction = DMA_FROM_DEVICE;
1144 cmd->transfersize = req->data_len;
1145 cmd->allowed = req->retries;
1146 cmd->timeout_per_command = req->timeout;
1147 return BLKPREP_OK;
1149 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1152 * Setup a REQ_TYPE_FS command. These are simple read/write request
1153 * from filesystems that still need to be translated to SCSI CDBs from
1154 * the ULD.
1156 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1158 struct scsi_cmnd *cmd;
1159 int ret = scsi_prep_state_check(sdev, req);
1161 if (ret != BLKPREP_OK)
1162 return ret;
1164 if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1165 && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1166 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1167 if (ret != BLKPREP_OK)
1168 return ret;
1172 * Filesystem requests must transfer data.
1174 BUG_ON(!req->nr_phys_segments);
1176 cmd = scsi_get_cmd_from_req(sdev, req);
1177 if (unlikely(!cmd))
1178 return BLKPREP_DEFER;
1180 memset(cmd->cmnd, 0, BLK_MAX_CDB);
1181 return scsi_init_io(cmd, GFP_ATOMIC);
1183 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1185 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1187 int ret = BLKPREP_OK;
1190 * If the device is not in running state we will reject some
1191 * or all commands.
1193 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1194 switch (sdev->sdev_state) {
1195 case SDEV_OFFLINE:
1197 * If the device is offline we refuse to process any
1198 * commands. The device must be brought online
1199 * before trying any recovery commands.
1201 sdev_printk(KERN_ERR, sdev,
1202 "rejecting I/O to offline device\n");
1203 ret = BLKPREP_KILL;
1204 break;
1205 case SDEV_DEL:
1207 * If the device is fully deleted, we refuse to
1208 * process any commands as well.
1210 sdev_printk(KERN_ERR, sdev,
1211 "rejecting I/O to dead device\n");
1212 ret = BLKPREP_KILL;
1213 break;
1214 case SDEV_QUIESCE:
1215 case SDEV_BLOCK:
1217 * If the devices is blocked we defer normal commands.
1219 if (!(req->cmd_flags & REQ_PREEMPT))
1220 ret = BLKPREP_DEFER;
1221 break;
1222 default:
1224 * For any other not fully online state we only allow
1225 * special commands. In particular any user initiated
1226 * command is not allowed.
1228 if (!(req->cmd_flags & REQ_PREEMPT))
1229 ret = BLKPREP_KILL;
1230 break;
1233 return ret;
1235 EXPORT_SYMBOL(scsi_prep_state_check);
1237 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1239 struct scsi_device *sdev = q->queuedata;
1241 switch (ret) {
1242 case BLKPREP_KILL:
1243 req->errors = DID_NO_CONNECT << 16;
1244 /* release the command and kill it */
1245 if (req->special) {
1246 struct scsi_cmnd *cmd = req->special;
1247 scsi_release_buffers(cmd);
1248 scsi_put_command(cmd);
1249 req->special = NULL;
1251 break;
1252 case BLKPREP_DEFER:
1254 * If we defer, the elv_next_request() returns NULL, but the
1255 * queue must be restarted, so we plug here if no returning
1256 * command will automatically do that.
1258 if (sdev->device_busy == 0)
1259 blk_plug_device(q);
1260 break;
1261 default:
1262 req->cmd_flags |= REQ_DONTPREP;
1265 return ret;
1267 EXPORT_SYMBOL(scsi_prep_return);
1269 int scsi_prep_fn(struct request_queue *q, struct request *req)
1271 struct scsi_device *sdev = q->queuedata;
1272 int ret = BLKPREP_KILL;
1274 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1275 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1276 return scsi_prep_return(q, req, ret);
1280 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1281 * return 0.
1283 * Called with the queue_lock held.
1285 static inline int scsi_dev_queue_ready(struct request_queue *q,
1286 struct scsi_device *sdev)
1288 if (sdev->device_busy >= sdev->queue_depth)
1289 return 0;
1290 if (sdev->device_busy == 0 && sdev->device_blocked) {
1292 * unblock after device_blocked iterates to zero
1294 if (--sdev->device_blocked == 0) {
1295 SCSI_LOG_MLQUEUE(3,
1296 sdev_printk(KERN_INFO, sdev,
1297 "unblocking device at zero depth\n"));
1298 } else {
1299 blk_plug_device(q);
1300 return 0;
1303 if (sdev->device_blocked)
1304 return 0;
1306 return 1;
1310 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1311 * return 0. We must end up running the queue again whenever 0 is
1312 * returned, else IO can hang.
1314 * Called with host_lock held.
1316 static inline int scsi_host_queue_ready(struct request_queue *q,
1317 struct Scsi_Host *shost,
1318 struct scsi_device *sdev)
1320 if (scsi_host_in_recovery(shost))
1321 return 0;
1322 if (shost->host_busy == 0 && shost->host_blocked) {
1324 * unblock after host_blocked iterates to zero
1326 if (--shost->host_blocked == 0) {
1327 SCSI_LOG_MLQUEUE(3,
1328 printk("scsi%d unblocking host at zero depth\n",
1329 shost->host_no));
1330 } else {
1331 blk_plug_device(q);
1332 return 0;
1335 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1336 shost->host_blocked || shost->host_self_blocked) {
1337 if (list_empty(&sdev->starved_entry))
1338 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1339 return 0;
1342 /* We're OK to process the command, so we can't be starved */
1343 if (!list_empty(&sdev->starved_entry))
1344 list_del_init(&sdev->starved_entry);
1346 return 1;
1350 * Kill a request for a dead device
1352 static void scsi_kill_request(struct request *req, struct request_queue *q)
1354 struct scsi_cmnd *cmd = req->special;
1355 struct scsi_device *sdev = cmd->device;
1356 struct Scsi_Host *shost = sdev->host;
1358 blkdev_dequeue_request(req);
1360 if (unlikely(cmd == NULL)) {
1361 printk(KERN_CRIT "impossible request in %s.\n",
1362 __FUNCTION__);
1363 BUG();
1366 scsi_init_cmd_errh(cmd);
1367 cmd->result = DID_NO_CONNECT << 16;
1368 atomic_inc(&cmd->device->iorequest_cnt);
1371 * SCSI request completion path will do scsi_device_unbusy(),
1372 * bump busy counts. To bump the counters, we need to dance
1373 * with the locks as normal issue path does.
1375 sdev->device_busy++;
1376 spin_unlock(sdev->request_queue->queue_lock);
1377 spin_lock(shost->host_lock);
1378 shost->host_busy++;
1379 spin_unlock(shost->host_lock);
1380 spin_lock(sdev->request_queue->queue_lock);
1382 __scsi_done(cmd);
1385 static void scsi_softirq_done(struct request *rq)
1387 struct scsi_cmnd *cmd = rq->completion_data;
1388 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
1389 int disposition;
1391 INIT_LIST_HEAD(&cmd->eh_entry);
1393 disposition = scsi_decide_disposition(cmd);
1394 if (disposition != SUCCESS &&
1395 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1396 sdev_printk(KERN_ERR, cmd->device,
1397 "timing out command, waited %lus\n",
1398 wait_for/HZ);
1399 disposition = SUCCESS;
1402 scsi_log_completion(cmd, disposition);
1404 switch (disposition) {
1405 case SUCCESS:
1406 scsi_finish_command(cmd);
1407 break;
1408 case NEEDS_RETRY:
1409 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1410 break;
1411 case ADD_TO_MLQUEUE:
1412 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1413 break;
1414 default:
1415 if (!scsi_eh_scmd_add(cmd, 0))
1416 scsi_finish_command(cmd);
1421 * Function: scsi_request_fn()
1423 * Purpose: Main strategy routine for SCSI.
1425 * Arguments: q - Pointer to actual queue.
1427 * Returns: Nothing
1429 * Lock status: IO request lock assumed to be held when called.
1431 static void scsi_request_fn(struct request_queue *q)
1433 struct scsi_device *sdev = q->queuedata;
1434 struct Scsi_Host *shost;
1435 struct scsi_cmnd *cmd;
1436 struct request *req;
1438 if (!sdev) {
1439 printk("scsi: killing requests for dead queue\n");
1440 while ((req = elv_next_request(q)) != NULL)
1441 scsi_kill_request(req, q);
1442 return;
1445 if(!get_device(&sdev->sdev_gendev))
1446 /* We must be tearing the block queue down already */
1447 return;
1450 * To start with, we keep looping until the queue is empty, or until
1451 * the host is no longer able to accept any more requests.
1453 shost = sdev->host;
1454 while (!blk_queue_plugged(q)) {
1455 int rtn;
1457 * get next queueable request. We do this early to make sure
1458 * that the request is fully prepared even if we cannot
1459 * accept it.
1461 req = elv_next_request(q);
1462 if (!req || !scsi_dev_queue_ready(q, sdev))
1463 break;
1465 if (unlikely(!scsi_device_online(sdev))) {
1466 sdev_printk(KERN_ERR, sdev,
1467 "rejecting I/O to offline device\n");
1468 scsi_kill_request(req, q);
1469 continue;
1474 * Remove the request from the request list.
1476 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1477 blkdev_dequeue_request(req);
1478 sdev->device_busy++;
1480 spin_unlock(q->queue_lock);
1481 cmd = req->special;
1482 if (unlikely(cmd == NULL)) {
1483 printk(KERN_CRIT "impossible request in %s.\n"
1484 "please mail a stack trace to "
1485 "linux-scsi@vger.kernel.org\n",
1486 __FUNCTION__);
1487 blk_dump_rq_flags(req, "foo");
1488 BUG();
1490 spin_lock(shost->host_lock);
1492 if (!scsi_host_queue_ready(q, shost, sdev))
1493 goto not_ready;
1494 if (scsi_target(sdev)->single_lun) {
1495 if (scsi_target(sdev)->starget_sdev_user &&
1496 scsi_target(sdev)->starget_sdev_user != sdev)
1497 goto not_ready;
1498 scsi_target(sdev)->starget_sdev_user = sdev;
1500 shost->host_busy++;
1503 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1504 * take the lock again.
1506 spin_unlock_irq(shost->host_lock);
1509 * Finally, initialize any error handling parameters, and set up
1510 * the timers for timeouts.
1512 scsi_init_cmd_errh(cmd);
1515 * Dispatch the command to the low-level driver.
1517 rtn = scsi_dispatch_cmd(cmd);
1518 spin_lock_irq(q->queue_lock);
1519 if(rtn) {
1520 /* we're refusing the command; because of
1521 * the way locks get dropped, we need to
1522 * check here if plugging is required */
1523 if(sdev->device_busy == 0)
1524 blk_plug_device(q);
1526 break;
1530 goto out;
1532 not_ready:
1533 spin_unlock_irq(shost->host_lock);
1536 * lock q, handle tag, requeue req, and decrement device_busy. We
1537 * must return with queue_lock held.
1539 * Decrementing device_busy without checking it is OK, as all such
1540 * cases (host limits or settings) should run the queue at some
1541 * later time.
1543 spin_lock_irq(q->queue_lock);
1544 blk_requeue_request(q, req);
1545 sdev->device_busy--;
1546 if(sdev->device_busy == 0)
1547 blk_plug_device(q);
1548 out:
1549 /* must be careful here...if we trigger the ->remove() function
1550 * we cannot be holding the q lock */
1551 spin_unlock_irq(q->queue_lock);
1552 put_device(&sdev->sdev_gendev);
1553 spin_lock_irq(q->queue_lock);
1556 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1558 struct device *host_dev;
1559 u64 bounce_limit = 0xffffffff;
1561 if (shost->unchecked_isa_dma)
1562 return BLK_BOUNCE_ISA;
1564 * Platforms with virtual-DMA translation
1565 * hardware have no practical limit.
1567 if (!PCI_DMA_BUS_IS_PHYS)
1568 return BLK_BOUNCE_ANY;
1570 host_dev = scsi_get_device(shost);
1571 if (host_dev && host_dev->dma_mask)
1572 bounce_limit = *host_dev->dma_mask;
1574 return bounce_limit;
1576 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1578 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1579 request_fn_proc *request_fn)
1581 struct request_queue *q;
1582 struct device *dev = shost->shost_gendev.parent;
1584 q = blk_init_queue(request_fn, NULL);
1585 if (!q)
1586 return NULL;
1589 * this limit is imposed by hardware restrictions
1591 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1592 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1594 blk_queue_max_sectors(q, shost->max_sectors);
1595 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1596 blk_queue_segment_boundary(q, shost->dma_boundary);
1597 dma_set_seg_boundary(dev, shost->dma_boundary);
1599 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1601 /* New queue, no concurrency on queue_flags */
1602 if (!shost->use_clustering)
1603 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
1606 * set a reasonable default alignment on word boundaries: the
1607 * host and device may alter it using
1608 * blk_queue_update_dma_alignment() later.
1610 blk_queue_dma_alignment(q, 0x03);
1612 return q;
1614 EXPORT_SYMBOL(__scsi_alloc_queue);
1616 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1618 struct request_queue *q;
1620 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1621 if (!q)
1622 return NULL;
1624 blk_queue_prep_rq(q, scsi_prep_fn);
1625 blk_queue_softirq_done(q, scsi_softirq_done);
1626 return q;
1629 void scsi_free_queue(struct request_queue *q)
1631 blk_cleanup_queue(q);
1635 * Function: scsi_block_requests()
1637 * Purpose: Utility function used by low-level drivers to prevent further
1638 * commands from being queued to the device.
1640 * Arguments: shost - Host in question
1642 * Returns: Nothing
1644 * Lock status: No locks are assumed held.
1646 * Notes: There is no timer nor any other means by which the requests
1647 * get unblocked other than the low-level driver calling
1648 * scsi_unblock_requests().
1650 void scsi_block_requests(struct Scsi_Host *shost)
1652 shost->host_self_blocked = 1;
1654 EXPORT_SYMBOL(scsi_block_requests);
1657 * Function: scsi_unblock_requests()
1659 * Purpose: Utility function used by low-level drivers to allow further
1660 * commands from being queued to the device.
1662 * Arguments: shost - Host in question
1664 * Returns: Nothing
1666 * Lock status: No locks are assumed held.
1668 * Notes: There is no timer nor any other means by which the requests
1669 * get unblocked other than the low-level driver calling
1670 * scsi_unblock_requests().
1672 * This is done as an API function so that changes to the
1673 * internals of the scsi mid-layer won't require wholesale
1674 * changes to drivers that use this feature.
1676 void scsi_unblock_requests(struct Scsi_Host *shost)
1678 shost->host_self_blocked = 0;
1679 scsi_run_host_queues(shost);
1681 EXPORT_SYMBOL(scsi_unblock_requests);
1683 int __init scsi_init_queue(void)
1685 int i;
1687 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1688 sizeof(struct scsi_io_context),
1689 0, 0, NULL);
1690 if (!scsi_io_context_cache) {
1691 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1692 return -ENOMEM;
1695 scsi_bidi_sdb_cache = kmem_cache_create("scsi_bidi_sdb",
1696 sizeof(struct scsi_data_buffer),
1697 0, 0, NULL);
1698 if (!scsi_bidi_sdb_cache) {
1699 printk(KERN_ERR "SCSI: can't init scsi bidi sdb cache\n");
1700 goto cleanup_io_context;
1703 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1704 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1705 int size = sgp->size * sizeof(struct scatterlist);
1707 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1708 SLAB_HWCACHE_ALIGN, NULL);
1709 if (!sgp->slab) {
1710 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1711 sgp->name);
1712 goto cleanup_bidi_sdb;
1715 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1716 sgp->slab);
1717 if (!sgp->pool) {
1718 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1719 sgp->name);
1720 goto cleanup_bidi_sdb;
1724 return 0;
1726 cleanup_bidi_sdb:
1727 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1728 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1729 if (sgp->pool)
1730 mempool_destroy(sgp->pool);
1731 if (sgp->slab)
1732 kmem_cache_destroy(sgp->slab);
1734 kmem_cache_destroy(scsi_bidi_sdb_cache);
1735 cleanup_io_context:
1736 kmem_cache_destroy(scsi_io_context_cache);
1738 return -ENOMEM;
1741 void scsi_exit_queue(void)
1743 int i;
1745 kmem_cache_destroy(scsi_io_context_cache);
1746 kmem_cache_destroy(scsi_bidi_sdb_cache);
1748 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1749 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1750 mempool_destroy(sgp->pool);
1751 kmem_cache_destroy(sgp->slab);
1756 * scsi_mode_select - issue a mode select
1757 * @sdev: SCSI device to be queried
1758 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1759 * @sp: Save page bit (0 == don't save, 1 == save)
1760 * @modepage: mode page being requested
1761 * @buffer: request buffer (may not be smaller than eight bytes)
1762 * @len: length of request buffer.
1763 * @timeout: command timeout
1764 * @retries: number of retries before failing
1765 * @data: returns a structure abstracting the mode header data
1766 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1767 * must be SCSI_SENSE_BUFFERSIZE big.
1769 * Returns zero if successful; negative error number or scsi
1770 * status on error
1774 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1775 unsigned char *buffer, int len, int timeout, int retries,
1776 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1778 unsigned char cmd[10];
1779 unsigned char *real_buffer;
1780 int ret;
1782 memset(cmd, 0, sizeof(cmd));
1783 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1785 if (sdev->use_10_for_ms) {
1786 if (len > 65535)
1787 return -EINVAL;
1788 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1789 if (!real_buffer)
1790 return -ENOMEM;
1791 memcpy(real_buffer + 8, buffer, len);
1792 len += 8;
1793 real_buffer[0] = 0;
1794 real_buffer[1] = 0;
1795 real_buffer[2] = data->medium_type;
1796 real_buffer[3] = data->device_specific;
1797 real_buffer[4] = data->longlba ? 0x01 : 0;
1798 real_buffer[5] = 0;
1799 real_buffer[6] = data->block_descriptor_length >> 8;
1800 real_buffer[7] = data->block_descriptor_length;
1802 cmd[0] = MODE_SELECT_10;
1803 cmd[7] = len >> 8;
1804 cmd[8] = len;
1805 } else {
1806 if (len > 255 || data->block_descriptor_length > 255 ||
1807 data->longlba)
1808 return -EINVAL;
1810 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1811 if (!real_buffer)
1812 return -ENOMEM;
1813 memcpy(real_buffer + 4, buffer, len);
1814 len += 4;
1815 real_buffer[0] = 0;
1816 real_buffer[1] = data->medium_type;
1817 real_buffer[2] = data->device_specific;
1818 real_buffer[3] = data->block_descriptor_length;
1821 cmd[0] = MODE_SELECT;
1822 cmd[4] = len;
1825 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1826 sshdr, timeout, retries);
1827 kfree(real_buffer);
1828 return ret;
1830 EXPORT_SYMBOL_GPL(scsi_mode_select);
1833 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1834 * @sdev: SCSI device to be queried
1835 * @dbd: set if mode sense will allow block descriptors to be returned
1836 * @modepage: mode page being requested
1837 * @buffer: request buffer (may not be smaller than eight bytes)
1838 * @len: length of request buffer.
1839 * @timeout: command timeout
1840 * @retries: number of retries before failing
1841 * @data: returns a structure abstracting the mode header data
1842 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1843 * must be SCSI_SENSE_BUFFERSIZE big.
1845 * Returns zero if unsuccessful, or the header offset (either 4
1846 * or 8 depending on whether a six or ten byte command was
1847 * issued) if successful.
1850 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1851 unsigned char *buffer, int len, int timeout, int retries,
1852 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1854 unsigned char cmd[12];
1855 int use_10_for_ms;
1856 int header_length;
1857 int result;
1858 struct scsi_sense_hdr my_sshdr;
1860 memset(data, 0, sizeof(*data));
1861 memset(&cmd[0], 0, 12);
1862 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1863 cmd[2] = modepage;
1865 /* caller might not be interested in sense, but we need it */
1866 if (!sshdr)
1867 sshdr = &my_sshdr;
1869 retry:
1870 use_10_for_ms = sdev->use_10_for_ms;
1872 if (use_10_for_ms) {
1873 if (len < 8)
1874 len = 8;
1876 cmd[0] = MODE_SENSE_10;
1877 cmd[8] = len;
1878 header_length = 8;
1879 } else {
1880 if (len < 4)
1881 len = 4;
1883 cmd[0] = MODE_SENSE;
1884 cmd[4] = len;
1885 header_length = 4;
1888 memset(buffer, 0, len);
1890 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1891 sshdr, timeout, retries);
1893 /* This code looks awful: what it's doing is making sure an
1894 * ILLEGAL REQUEST sense return identifies the actual command
1895 * byte as the problem. MODE_SENSE commands can return
1896 * ILLEGAL REQUEST if the code page isn't supported */
1898 if (use_10_for_ms && !scsi_status_is_good(result) &&
1899 (driver_byte(result) & DRIVER_SENSE)) {
1900 if (scsi_sense_valid(sshdr)) {
1901 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1902 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1904 * Invalid command operation code
1906 sdev->use_10_for_ms = 0;
1907 goto retry;
1912 if(scsi_status_is_good(result)) {
1913 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1914 (modepage == 6 || modepage == 8))) {
1915 /* Initio breakage? */
1916 header_length = 0;
1917 data->length = 13;
1918 data->medium_type = 0;
1919 data->device_specific = 0;
1920 data->longlba = 0;
1921 data->block_descriptor_length = 0;
1922 } else if(use_10_for_ms) {
1923 data->length = buffer[0]*256 + buffer[1] + 2;
1924 data->medium_type = buffer[2];
1925 data->device_specific = buffer[3];
1926 data->longlba = buffer[4] & 0x01;
1927 data->block_descriptor_length = buffer[6]*256
1928 + buffer[7];
1929 } else {
1930 data->length = buffer[0] + 1;
1931 data->medium_type = buffer[1];
1932 data->device_specific = buffer[2];
1933 data->block_descriptor_length = buffer[3];
1935 data->header_length = header_length;
1938 return result;
1940 EXPORT_SYMBOL(scsi_mode_sense);
1943 * scsi_test_unit_ready - test if unit is ready
1944 * @sdev: scsi device to change the state of.
1945 * @timeout: command timeout
1946 * @retries: number of retries before failing
1947 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
1948 * returning sense. Make sure that this is cleared before passing
1949 * in.
1951 * Returns zero if unsuccessful or an error if TUR failed. For
1952 * removable media, a return of NOT_READY or UNIT_ATTENTION is
1953 * translated to success, with the ->changed flag updated.
1956 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
1957 struct scsi_sense_hdr *sshdr_external)
1959 char cmd[] = {
1960 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1962 struct scsi_sense_hdr *sshdr;
1963 int result;
1965 if (!sshdr_external)
1966 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
1967 else
1968 sshdr = sshdr_external;
1970 /* try to eat the UNIT_ATTENTION if there are enough retries */
1971 do {
1972 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
1973 timeout, retries);
1974 } while ((driver_byte(result) & DRIVER_SENSE) &&
1975 sshdr && sshdr->sense_key == UNIT_ATTENTION &&
1976 --retries);
1978 if (!sshdr)
1979 /* could not allocate sense buffer, so can't process it */
1980 return result;
1982 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
1984 if ((scsi_sense_valid(sshdr)) &&
1985 ((sshdr->sense_key == UNIT_ATTENTION) ||
1986 (sshdr->sense_key == NOT_READY))) {
1987 sdev->changed = 1;
1988 result = 0;
1991 if (!sshdr_external)
1992 kfree(sshdr);
1993 return result;
1995 EXPORT_SYMBOL(scsi_test_unit_ready);
1998 * scsi_device_set_state - Take the given device through the device state model.
1999 * @sdev: scsi device to change the state of.
2000 * @state: state to change to.
2002 * Returns zero if unsuccessful or an error if the requested
2003 * transition is illegal.
2006 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2008 enum scsi_device_state oldstate = sdev->sdev_state;
2010 if (state == oldstate)
2011 return 0;
2013 switch (state) {
2014 case SDEV_CREATED:
2015 /* There are no legal states that come back to
2016 * created. This is the manually initialised start
2017 * state */
2018 goto illegal;
2020 case SDEV_RUNNING:
2021 switch (oldstate) {
2022 case SDEV_CREATED:
2023 case SDEV_OFFLINE:
2024 case SDEV_QUIESCE:
2025 case SDEV_BLOCK:
2026 break;
2027 default:
2028 goto illegal;
2030 break;
2032 case SDEV_QUIESCE:
2033 switch (oldstate) {
2034 case SDEV_RUNNING:
2035 case SDEV_OFFLINE:
2036 break;
2037 default:
2038 goto illegal;
2040 break;
2042 case SDEV_OFFLINE:
2043 switch (oldstate) {
2044 case SDEV_CREATED:
2045 case SDEV_RUNNING:
2046 case SDEV_QUIESCE:
2047 case SDEV_BLOCK:
2048 break;
2049 default:
2050 goto illegal;
2052 break;
2054 case SDEV_BLOCK:
2055 switch (oldstate) {
2056 case SDEV_CREATED:
2057 case SDEV_RUNNING:
2058 break;
2059 default:
2060 goto illegal;
2062 break;
2064 case SDEV_CANCEL:
2065 switch (oldstate) {
2066 case SDEV_CREATED:
2067 case SDEV_RUNNING:
2068 case SDEV_QUIESCE:
2069 case SDEV_OFFLINE:
2070 case SDEV_BLOCK:
2071 break;
2072 default:
2073 goto illegal;
2075 break;
2077 case SDEV_DEL:
2078 switch (oldstate) {
2079 case SDEV_CREATED:
2080 case SDEV_RUNNING:
2081 case SDEV_OFFLINE:
2082 case SDEV_CANCEL:
2083 break;
2084 default:
2085 goto illegal;
2087 break;
2090 sdev->sdev_state = state;
2091 return 0;
2093 illegal:
2094 SCSI_LOG_ERROR_RECOVERY(1,
2095 sdev_printk(KERN_ERR, sdev,
2096 "Illegal state transition %s->%s\n",
2097 scsi_device_state_name(oldstate),
2098 scsi_device_state_name(state))
2100 return -EINVAL;
2102 EXPORT_SYMBOL(scsi_device_set_state);
2105 * sdev_evt_emit - emit a single SCSI device uevent
2106 * @sdev: associated SCSI device
2107 * @evt: event to emit
2109 * Send a single uevent (scsi_event) to the associated scsi_device.
2111 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2113 int idx = 0;
2114 char *envp[3];
2116 switch (evt->evt_type) {
2117 case SDEV_EVT_MEDIA_CHANGE:
2118 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2119 break;
2121 default:
2122 /* do nothing */
2123 break;
2126 envp[idx++] = NULL;
2128 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2132 * sdev_evt_thread - send a uevent for each scsi event
2133 * @work: work struct for scsi_device
2135 * Dispatch queued events to their associated scsi_device kobjects
2136 * as uevents.
2138 void scsi_evt_thread(struct work_struct *work)
2140 struct scsi_device *sdev;
2141 LIST_HEAD(event_list);
2143 sdev = container_of(work, struct scsi_device, event_work);
2145 while (1) {
2146 struct scsi_event *evt;
2147 struct list_head *this, *tmp;
2148 unsigned long flags;
2150 spin_lock_irqsave(&sdev->list_lock, flags);
2151 list_splice_init(&sdev->event_list, &event_list);
2152 spin_unlock_irqrestore(&sdev->list_lock, flags);
2154 if (list_empty(&event_list))
2155 break;
2157 list_for_each_safe(this, tmp, &event_list) {
2158 evt = list_entry(this, struct scsi_event, node);
2159 list_del(&evt->node);
2160 scsi_evt_emit(sdev, evt);
2161 kfree(evt);
2167 * sdev_evt_send - send asserted event to uevent thread
2168 * @sdev: scsi_device event occurred on
2169 * @evt: event to send
2171 * Assert scsi device event asynchronously.
2173 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2175 unsigned long flags;
2177 #if 0
2178 /* FIXME: currently this check eliminates all media change events
2179 * for polled devices. Need to update to discriminate between AN
2180 * and polled events */
2181 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2182 kfree(evt);
2183 return;
2185 #endif
2187 spin_lock_irqsave(&sdev->list_lock, flags);
2188 list_add_tail(&evt->node, &sdev->event_list);
2189 schedule_work(&sdev->event_work);
2190 spin_unlock_irqrestore(&sdev->list_lock, flags);
2192 EXPORT_SYMBOL_GPL(sdev_evt_send);
2195 * sdev_evt_alloc - allocate a new scsi event
2196 * @evt_type: type of event to allocate
2197 * @gfpflags: GFP flags for allocation
2199 * Allocates and returns a new scsi_event.
2201 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2202 gfp_t gfpflags)
2204 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2205 if (!evt)
2206 return NULL;
2208 evt->evt_type = evt_type;
2209 INIT_LIST_HEAD(&evt->node);
2211 /* evt_type-specific initialization, if any */
2212 switch (evt_type) {
2213 case SDEV_EVT_MEDIA_CHANGE:
2214 default:
2215 /* do nothing */
2216 break;
2219 return evt;
2221 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2224 * sdev_evt_send_simple - send asserted event to uevent thread
2225 * @sdev: scsi_device event occurred on
2226 * @evt_type: type of event to send
2227 * @gfpflags: GFP flags for allocation
2229 * Assert scsi device event asynchronously, given an event type.
2231 void sdev_evt_send_simple(struct scsi_device *sdev,
2232 enum scsi_device_event evt_type, gfp_t gfpflags)
2234 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2235 if (!evt) {
2236 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2237 evt_type);
2238 return;
2241 sdev_evt_send(sdev, evt);
2243 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2246 * scsi_device_quiesce - Block user issued commands.
2247 * @sdev: scsi device to quiesce.
2249 * This works by trying to transition to the SDEV_QUIESCE state
2250 * (which must be a legal transition). When the device is in this
2251 * state, only special requests will be accepted, all others will
2252 * be deferred. Since special requests may also be requeued requests,
2253 * a successful return doesn't guarantee the device will be
2254 * totally quiescent.
2256 * Must be called with user context, may sleep.
2258 * Returns zero if unsuccessful or an error if not.
2261 scsi_device_quiesce(struct scsi_device *sdev)
2263 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2264 if (err)
2265 return err;
2267 scsi_run_queue(sdev->request_queue);
2268 while (sdev->device_busy) {
2269 msleep_interruptible(200);
2270 scsi_run_queue(sdev->request_queue);
2272 return 0;
2274 EXPORT_SYMBOL(scsi_device_quiesce);
2277 * scsi_device_resume - Restart user issued commands to a quiesced device.
2278 * @sdev: scsi device to resume.
2280 * Moves the device from quiesced back to running and restarts the
2281 * queues.
2283 * Must be called with user context, may sleep.
2285 void
2286 scsi_device_resume(struct scsi_device *sdev)
2288 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2289 return;
2290 scsi_run_queue(sdev->request_queue);
2292 EXPORT_SYMBOL(scsi_device_resume);
2294 static void
2295 device_quiesce_fn(struct scsi_device *sdev, void *data)
2297 scsi_device_quiesce(sdev);
2300 void
2301 scsi_target_quiesce(struct scsi_target *starget)
2303 starget_for_each_device(starget, NULL, device_quiesce_fn);
2305 EXPORT_SYMBOL(scsi_target_quiesce);
2307 static void
2308 device_resume_fn(struct scsi_device *sdev, void *data)
2310 scsi_device_resume(sdev);
2313 void
2314 scsi_target_resume(struct scsi_target *starget)
2316 starget_for_each_device(starget, NULL, device_resume_fn);
2318 EXPORT_SYMBOL(scsi_target_resume);
2321 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2322 * @sdev: device to block
2324 * Block request made by scsi lld's to temporarily stop all
2325 * scsi commands on the specified device. Called from interrupt
2326 * or normal process context.
2328 * Returns zero if successful or error if not
2330 * Notes:
2331 * This routine transitions the device to the SDEV_BLOCK state
2332 * (which must be a legal transition). When the device is in this
2333 * state, all commands are deferred until the scsi lld reenables
2334 * the device with scsi_device_unblock or device_block_tmo fires.
2335 * This routine assumes the host_lock is held on entry.
2338 scsi_internal_device_block(struct scsi_device *sdev)
2340 struct request_queue *q = sdev->request_queue;
2341 unsigned long flags;
2342 int err = 0;
2344 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2345 if (err)
2346 return err;
2349 * The device has transitioned to SDEV_BLOCK. Stop the
2350 * block layer from calling the midlayer with this device's
2351 * request queue.
2353 spin_lock_irqsave(q->queue_lock, flags);
2354 blk_stop_queue(q);
2355 spin_unlock_irqrestore(q->queue_lock, flags);
2357 return 0;
2359 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2362 * scsi_internal_device_unblock - resume a device after a block request
2363 * @sdev: device to resume
2365 * Called by scsi lld's or the midlayer to restart the device queue
2366 * for the previously suspended scsi device. Called from interrupt or
2367 * normal process context.
2369 * Returns zero if successful or error if not.
2371 * Notes:
2372 * This routine transitions the device to the SDEV_RUNNING state
2373 * (which must be a legal transition) allowing the midlayer to
2374 * goose the queue for this device. This routine assumes the
2375 * host_lock is held upon entry.
2378 scsi_internal_device_unblock(struct scsi_device *sdev)
2380 struct request_queue *q = sdev->request_queue;
2381 int err;
2382 unsigned long flags;
2385 * Try to transition the scsi device to SDEV_RUNNING
2386 * and goose the device queue if successful.
2388 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2389 if (err)
2390 return err;
2392 spin_lock_irqsave(q->queue_lock, flags);
2393 blk_start_queue(q);
2394 spin_unlock_irqrestore(q->queue_lock, flags);
2396 return 0;
2398 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2400 static void
2401 device_block(struct scsi_device *sdev, void *data)
2403 scsi_internal_device_block(sdev);
2406 static int
2407 target_block(struct device *dev, void *data)
2409 if (scsi_is_target_device(dev))
2410 starget_for_each_device(to_scsi_target(dev), NULL,
2411 device_block);
2412 return 0;
2415 void
2416 scsi_target_block(struct device *dev)
2418 if (scsi_is_target_device(dev))
2419 starget_for_each_device(to_scsi_target(dev), NULL,
2420 device_block);
2421 else
2422 device_for_each_child(dev, NULL, target_block);
2424 EXPORT_SYMBOL_GPL(scsi_target_block);
2426 static void
2427 device_unblock(struct scsi_device *sdev, void *data)
2429 scsi_internal_device_unblock(sdev);
2432 static int
2433 target_unblock(struct device *dev, void *data)
2435 if (scsi_is_target_device(dev))
2436 starget_for_each_device(to_scsi_target(dev), NULL,
2437 device_unblock);
2438 return 0;
2441 void
2442 scsi_target_unblock(struct device *dev)
2444 if (scsi_is_target_device(dev))
2445 starget_for_each_device(to_scsi_target(dev), NULL,
2446 device_unblock);
2447 else
2448 device_for_each_child(dev, NULL, target_unblock);
2450 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2453 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2454 * @sgl: scatter-gather list
2455 * @sg_count: number of segments in sg
2456 * @offset: offset in bytes into sg, on return offset into the mapped area
2457 * @len: bytes to map, on return number of bytes mapped
2459 * Returns virtual address of the start of the mapped page
2461 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2462 size_t *offset, size_t *len)
2464 int i;
2465 size_t sg_len = 0, len_complete = 0;
2466 struct scatterlist *sg;
2467 struct page *page;
2469 WARN_ON(!irqs_disabled());
2471 for_each_sg(sgl, sg, sg_count, i) {
2472 len_complete = sg_len; /* Complete sg-entries */
2473 sg_len += sg->length;
2474 if (sg_len > *offset)
2475 break;
2478 if (unlikely(i == sg_count)) {
2479 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2480 "elements %d\n",
2481 __FUNCTION__, sg_len, *offset, sg_count);
2482 WARN_ON(1);
2483 return NULL;
2486 /* Offset starting from the beginning of first page in this sg-entry */
2487 *offset = *offset - len_complete + sg->offset;
2489 /* Assumption: contiguous pages can be accessed as "page + i" */
2490 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2491 *offset &= ~PAGE_MASK;
2493 /* Bytes in this sg-entry from *offset to the end of the page */
2494 sg_len = PAGE_SIZE - *offset;
2495 if (*len > sg_len)
2496 *len = sg_len;
2498 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2500 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2503 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2504 * @virt: virtual address to be unmapped
2506 void scsi_kunmap_atomic_sg(void *virt)
2508 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2510 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);