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.
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/completion.h>
13 #include <linux/kernel.h>
14 #include <linux/mempool.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/pci.h>
18 #include <linux/delay.h>
19 #include <linux/hardirq.h>
20 #include <linux/scatterlist.h>
22 #include <scsi/scsi.h>
23 #include <scsi/scsi_cmnd.h>
24 #include <scsi/scsi_dbg.h>
25 #include <scsi/scsi_device.h>
26 #include <scsi/scsi_driver.h>
27 #include <scsi/scsi_eh.h>
28 #include <scsi/scsi_host.h>
30 #include "scsi_priv.h"
31 #include "scsi_logging.h"
34 #define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
35 #define SG_MEMPOOL_SIZE 2
37 struct scsi_host_sg_pool {
40 struct kmem_cache *slab;
44 #define SP(x) { x, "sgpool-" #x }
45 static struct scsi_host_sg_pool scsi_sg_pools[] = {
54 static void scsi_run_queue(struct request_queue *q);
57 * Function: scsi_unprep_request()
59 * Purpose: Remove all preparation done for a request, including its
60 * associated scsi_cmnd, so that it can be requeued.
62 * Arguments: req - request to unprepare
64 * Lock status: Assumed that no locks are held upon entry.
68 static void scsi_unprep_request(struct request *req)
70 struct scsi_cmnd *cmd = req->special;
72 req->cmd_flags &= ~REQ_DONTPREP;
75 scsi_put_command(cmd);
79 * Function: scsi_queue_insert()
81 * Purpose: Insert a command in the midlevel queue.
83 * Arguments: cmd - command that we are adding to queue.
84 * reason - why we are inserting command to queue.
86 * Lock status: Assumed that lock is not held upon entry.
90 * Notes: We do this for one of two cases. Either the host is busy
91 * and it cannot accept any more commands for the time being,
92 * or the device returned QUEUE_FULL and can accept no more
94 * Notes: This could be called either from an interrupt context or a
95 * normal process context.
97 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
99 struct Scsi_Host *host = cmd->device->host;
100 struct scsi_device *device = cmd->device;
101 struct request_queue *q = device->request_queue;
105 printk("Inserting command %p into mlqueue\n", cmd));
108 * Set the appropriate busy bit for the device/host.
110 * If the host/device isn't busy, assume that something actually
111 * completed, and that we should be able to queue a command now.
113 * Note that the prior mid-layer assumption that any host could
114 * always queue at least one command is now broken. The mid-layer
115 * will implement a user specifiable stall (see
116 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
117 * if a command is requeued with no other commands outstanding
118 * either for the device or for the host.
120 if (reason == SCSI_MLQUEUE_HOST_BUSY)
121 host->host_blocked = host->max_host_blocked;
122 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
123 device->device_blocked = device->max_device_blocked;
126 * Decrement the counters, since these commands are no longer
127 * active on the host/device.
129 scsi_device_unbusy(device);
132 * Requeue this command. It will go before all other commands
133 * that are already in the queue.
135 * NOTE: there is magic here about the way the queue is plugged if
136 * we have no outstanding commands.
138 * Although we *don't* plug the queue, we call the request
139 * function. The SCSI request function detects the blocked condition
140 * and plugs the queue appropriately.
142 spin_lock_irqsave(q->queue_lock, flags);
143 blk_requeue_request(q, cmd->request);
144 spin_unlock_irqrestore(q->queue_lock, flags);
152 * scsi_execute - insert request and wait for the result
155 * @data_direction: data direction
156 * @buffer: data buffer
157 * @bufflen: len of buffer
158 * @sense: optional sense buffer
159 * @timeout: request timeout in seconds
160 * @retries: number of times to retry request
161 * @flags: or into request flags;
163 * returns the req->errors value which is the scsi_cmnd result
166 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
167 int data_direction, void *buffer, unsigned bufflen,
168 unsigned char *sense, int timeout, int retries, int flags)
171 int write = (data_direction == DMA_TO_DEVICE);
172 int ret = DRIVER_ERROR << 24;
174 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
176 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
177 buffer, bufflen, __GFP_WAIT))
180 req->cmd_len = COMMAND_SIZE(cmd[0]);
181 memcpy(req->cmd, cmd, req->cmd_len);
184 req->retries = retries;
185 req->timeout = timeout;
186 req->cmd_type = REQ_TYPE_BLOCK_PC;
187 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
190 * head injection *required* here otherwise quiesce won't work
192 blk_execute_rq(req->q, NULL, req, 1);
196 blk_put_request(req);
200 EXPORT_SYMBOL(scsi_execute);
203 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
204 int data_direction, void *buffer, unsigned bufflen,
205 struct scsi_sense_hdr *sshdr, int timeout, int retries)
211 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
213 return DRIVER_ERROR << 24;
215 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
216 sense, timeout, retries, 0);
218 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
223 EXPORT_SYMBOL(scsi_execute_req);
225 struct scsi_io_context {
227 void (*done)(void *data, char *sense, int result, int resid);
228 char sense[SCSI_SENSE_BUFFERSIZE];
231 static struct kmem_cache *scsi_io_context_cache;
233 static void scsi_end_async(struct request *req, int uptodate)
235 struct scsi_io_context *sioc = req->end_io_data;
238 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
240 kmem_cache_free(scsi_io_context_cache, sioc);
241 __blk_put_request(req->q, req);
244 static int scsi_merge_bio(struct request *rq, struct bio *bio)
246 struct request_queue *q = rq->q;
248 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
249 if (rq_data_dir(rq) == WRITE)
250 bio->bi_rw |= (1 << BIO_RW);
251 blk_queue_bounce(q, &bio);
253 return blk_rq_append_bio(q, rq, bio);
256 static void scsi_bi_endio(struct bio *bio, int error)
262 * scsi_req_map_sg - map a scatterlist into a request
263 * @rq: request to fill
265 * @nsegs: number of elements
266 * @bufflen: len of buffer
267 * @gfp: memory allocation flags
269 * scsi_req_map_sg maps a scatterlist into a request so that the
270 * request can be sent to the block layer. We do not trust the scatterlist
271 * sent to use, as some ULDs use that struct to only organize the pages.
273 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
274 int nsegs, unsigned bufflen, gfp_t gfp)
276 struct request_queue *q = rq->q;
277 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
278 unsigned int data_len = bufflen, len, bytes, off;
279 struct scatterlist *sg;
281 struct bio *bio = NULL;
282 int i, err, nr_vecs = 0;
284 for_each_sg(sgl, sg, nsegs, i) {
290 while (len > 0 && data_len > 0) {
292 * sg sends a scatterlist that is larger than
293 * the data_len it wants transferred for certain
296 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
297 bytes = min(bytes, data_len);
300 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
303 bio = bio_alloc(gfp, nr_vecs);
308 bio->bi_end_io = scsi_bi_endio;
311 if (bio_add_pc_page(q, bio, page, bytes, off) !=
318 if (bio->bi_vcnt >= nr_vecs) {
319 err = scsi_merge_bio(rq, bio);
334 rq->buffer = rq->data = NULL;
335 rq->data_len = bufflen;
339 while ((bio = rq->bio) != NULL) {
340 rq->bio = bio->bi_next;
342 * call endio instead of bio_put incase it was bounced
351 * scsi_execute_async - insert request
354 * @cmd_len: length of scsi cdb
355 * @data_direction: data direction
356 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
357 * @bufflen: len of buffer
358 * @use_sg: if buffer is a scatterlist this is the number of elements
359 * @timeout: request timeout in seconds
360 * @retries: number of times to retry request
361 * @flags: or into request flags
363 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
364 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
365 int use_sg, int timeout, int retries, void *privdata,
366 void (*done)(void *, char *, int, int), gfp_t gfp)
369 struct scsi_io_context *sioc;
371 int write = (data_direction == DMA_TO_DEVICE);
373 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
375 return DRIVER_ERROR << 24;
377 req = blk_get_request(sdev->request_queue, write, gfp);
380 req->cmd_type = REQ_TYPE_BLOCK_PC;
381 req->cmd_flags |= REQ_QUIET;
384 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
386 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
391 req->cmd_len = cmd_len;
392 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
393 memcpy(req->cmd, cmd, req->cmd_len);
394 req->sense = sioc->sense;
396 req->timeout = timeout;
397 req->retries = retries;
398 req->end_io_data = sioc;
400 sioc->data = privdata;
403 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
407 blk_put_request(req);
409 kmem_cache_free(scsi_io_context_cache, sioc);
410 return DRIVER_ERROR << 24;
412 EXPORT_SYMBOL_GPL(scsi_execute_async);
415 * Function: scsi_init_cmd_errh()
417 * Purpose: Initialize cmd fields related to error handling.
419 * Arguments: cmd - command that is ready to be queued.
421 * Notes: This function has the job of initializing a number of
422 * fields related to error handling. Typically this will
423 * be called once for each command, as required.
425 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
427 cmd->serial_number = 0;
429 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
430 if (cmd->cmd_len == 0)
431 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
434 void scsi_device_unbusy(struct scsi_device *sdev)
436 struct Scsi_Host *shost = sdev->host;
439 spin_lock_irqsave(shost->host_lock, flags);
441 if (unlikely(scsi_host_in_recovery(shost) &&
442 (shost->host_failed || shost->host_eh_scheduled)))
443 scsi_eh_wakeup(shost);
444 spin_unlock(shost->host_lock);
445 spin_lock(sdev->request_queue->queue_lock);
447 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
451 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
452 * and call blk_run_queue for all the scsi_devices on the target -
453 * including current_sdev first.
455 * Called with *no* scsi locks held.
457 static void scsi_single_lun_run(struct scsi_device *current_sdev)
459 struct Scsi_Host *shost = current_sdev->host;
460 struct scsi_device *sdev, *tmp;
461 struct scsi_target *starget = scsi_target(current_sdev);
464 spin_lock_irqsave(shost->host_lock, flags);
465 starget->starget_sdev_user = NULL;
466 spin_unlock_irqrestore(shost->host_lock, flags);
469 * Call blk_run_queue for all LUNs on the target, starting with
470 * current_sdev. We race with others (to set starget_sdev_user),
471 * but in most cases, we will be first. Ideally, each LU on the
472 * target would get some limited time or requests on the target.
474 blk_run_queue(current_sdev->request_queue);
476 spin_lock_irqsave(shost->host_lock, flags);
477 if (starget->starget_sdev_user)
479 list_for_each_entry_safe(sdev, tmp, &starget->devices,
480 same_target_siblings) {
481 if (sdev == current_sdev)
483 if (scsi_device_get(sdev))
486 spin_unlock_irqrestore(shost->host_lock, flags);
487 blk_run_queue(sdev->request_queue);
488 spin_lock_irqsave(shost->host_lock, flags);
490 scsi_device_put(sdev);
493 spin_unlock_irqrestore(shost->host_lock, flags);
497 * Function: scsi_run_queue()
499 * Purpose: Select a proper request queue to serve next
501 * Arguments: q - last request's queue
505 * Notes: The previous command was completely finished, start
506 * a new one if possible.
508 static void scsi_run_queue(struct request_queue *q)
510 struct scsi_device *sdev = q->queuedata;
511 struct Scsi_Host *shost = sdev->host;
514 if (sdev->single_lun)
515 scsi_single_lun_run(sdev);
517 spin_lock_irqsave(shost->host_lock, flags);
518 while (!list_empty(&shost->starved_list) &&
519 !shost->host_blocked && !shost->host_self_blocked &&
520 !((shost->can_queue > 0) &&
521 (shost->host_busy >= shost->can_queue))) {
523 * As long as shost is accepting commands and we have
524 * starved queues, call blk_run_queue. scsi_request_fn
525 * drops the queue_lock and can add us back to the
528 * host_lock protects the starved_list and starved_entry.
529 * scsi_request_fn must get the host_lock before checking
530 * or modifying starved_list or starved_entry.
532 sdev = list_entry(shost->starved_list.next,
533 struct scsi_device, starved_entry);
534 list_del_init(&sdev->starved_entry);
535 spin_unlock_irqrestore(shost->host_lock, flags);
538 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
539 !test_and_set_bit(QUEUE_FLAG_REENTER,
540 &sdev->request_queue->queue_flags)) {
541 blk_run_queue(sdev->request_queue);
542 clear_bit(QUEUE_FLAG_REENTER,
543 &sdev->request_queue->queue_flags);
545 blk_run_queue(sdev->request_queue);
547 spin_lock_irqsave(shost->host_lock, flags);
548 if (unlikely(!list_empty(&sdev->starved_entry)))
550 * sdev lost a race, and was put back on the
551 * starved list. This is unlikely but without this
552 * in theory we could loop forever.
556 spin_unlock_irqrestore(shost->host_lock, flags);
562 * Function: scsi_requeue_command()
564 * Purpose: Handle post-processing of completed commands.
566 * Arguments: q - queue to operate on
567 * cmd - command that may need to be requeued.
571 * Notes: After command completion, there may be blocks left
572 * over which weren't finished by the previous command
573 * this can be for a number of reasons - the main one is
574 * I/O errors in the middle of the request, in which case
575 * we need to request the blocks that come after the bad
577 * Notes: Upon return, cmd is a stale pointer.
579 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
581 struct request *req = cmd->request;
584 scsi_unprep_request(req);
585 spin_lock_irqsave(q->queue_lock, flags);
586 blk_requeue_request(q, req);
587 spin_unlock_irqrestore(q->queue_lock, flags);
592 void scsi_next_command(struct scsi_cmnd *cmd)
594 struct scsi_device *sdev = cmd->device;
595 struct request_queue *q = sdev->request_queue;
597 /* need to hold a reference on the device before we let go of the cmd */
598 get_device(&sdev->sdev_gendev);
600 scsi_put_command(cmd);
603 /* ok to remove device now */
604 put_device(&sdev->sdev_gendev);
607 void scsi_run_host_queues(struct Scsi_Host *shost)
609 struct scsi_device *sdev;
611 shost_for_each_device(sdev, shost)
612 scsi_run_queue(sdev->request_queue);
616 * Function: scsi_end_request()
618 * Purpose: Post-processing of completed commands (usually invoked at end
619 * of upper level post-processing and scsi_io_completion).
621 * Arguments: cmd - command that is complete.
622 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
623 * bytes - number of bytes of completed I/O
624 * requeue - indicates whether we should requeue leftovers.
626 * Lock status: Assumed that lock is not held upon entry.
628 * Returns: cmd if requeue required, NULL otherwise.
630 * Notes: This is called for block device requests in order to
631 * mark some number of sectors as complete.
633 * We are guaranteeing that the request queue will be goosed
634 * at some point during this call.
635 * Notes: If cmd was requeued, upon return it will be a stale pointer.
637 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
638 int bytes, int requeue)
640 struct request_queue *q = cmd->device->request_queue;
641 struct request *req = cmd->request;
645 * If there are blocks left over at the end, set up the command
646 * to queue the remainder of them.
648 if (end_that_request_chunk(req, uptodate, bytes)) {
649 int leftover = (req->hard_nr_sectors << 9);
651 if (blk_pc_request(req))
652 leftover = req->data_len;
654 /* kill remainder if no retrys */
655 if (!uptodate && blk_noretry_request(req))
656 end_that_request_chunk(req, 0, leftover);
660 * Bleah. Leftovers again. Stick the
661 * leftovers in the front of the
662 * queue, and goose the queue again.
664 scsi_requeue_command(q, cmd);
671 add_disk_randomness(req->rq_disk);
673 spin_lock_irqsave(q->queue_lock, flags);
674 if (blk_rq_tagged(req))
675 blk_queue_end_tag(q, req);
676 end_that_request_last(req, uptodate);
677 spin_unlock_irqrestore(q->queue_lock, flags);
680 * This will goose the queue request function at the end, so we don't
681 * need to worry about launching another command.
683 scsi_next_command(cmd);
688 * The maximum number of SG segments that we will put inside a scatterlist
689 * (unless chaining is used). Should ideally fit inside a single page, to
690 * avoid a higher order allocation.
692 #define SCSI_MAX_SG_SEGMENTS 128
695 * Like SCSI_MAX_SG_SEGMENTS, but for archs that have sg chaining. This limit
696 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
698 #define SCSI_MAX_SG_CHAIN_SEGMENTS 2048
700 static inline unsigned int scsi_sgtable_index(unsigned short nents)
717 case 65 ... SCSI_MAX_SG_SEGMENTS:
721 printk(KERN_ERR "scsi: bad segment count=%d\n", nents);
728 struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
730 struct scsi_host_sg_pool *sgp;
731 struct scatterlist *sgl, *prev, *ret;
735 BUG_ON(!cmd->use_sg);
741 if (this > SCSI_MAX_SG_SEGMENTS) {
742 this = SCSI_MAX_SG_SEGMENTS - 1;
743 index = SG_MEMPOOL_NR - 1;
745 index = scsi_sgtable_index(this);
749 sgp = scsi_sg_pools + index;
751 sgl = mempool_alloc(sgp->pool, gfp_mask);
755 memset(sgl, 0, sizeof(*sgl) * sgp->size);
758 * first loop through, set initial index and return value
761 cmd->sglist_len = index;
766 * chain previous sglist, if any. we know the previous
767 * sglist must be the biggest one, or we would not have
768 * ended up doing another loop.
771 sg_chain(prev, SCSI_MAX_SG_SEGMENTS, sgl);
774 * don't allow subsequent mempool allocs to sleep, it would
775 * violate the mempool principle.
777 gfp_mask &= ~__GFP_WAIT;
778 gfp_mask |= __GFP_HIGH;
783 * ->use_sg may get modified after dma mapping has potentially
784 * shrunk the number of segments, so keep a copy of it for free.
786 cmd->__use_sg = cmd->use_sg;
791 * Free entries chained off ret. Since we were trying to
792 * allocate another sglist, we know that all entries are of
795 sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
797 ret = &ret[SCSI_MAX_SG_SEGMENTS - 1];
799 while ((sgl = sg_chain_ptr(ret)) != NULL) {
800 ret = &sgl[SCSI_MAX_SG_SEGMENTS - 1];
801 mempool_free(sgl, sgp->pool);
804 mempool_free(prev, sgp->pool);
809 EXPORT_SYMBOL(scsi_alloc_sgtable);
811 void scsi_free_sgtable(struct scsi_cmnd *cmd)
813 struct scatterlist *sgl = cmd->request_buffer;
814 struct scsi_host_sg_pool *sgp;
816 BUG_ON(cmd->sglist_len >= SG_MEMPOOL_NR);
819 * if this is the biggest size sglist, check if we have
820 * chained parts we need to free
822 if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {
823 unsigned short this, left;
824 struct scatterlist *next;
827 left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);
828 next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);
829 while (left && next) {
832 if (this > SCSI_MAX_SG_SEGMENTS) {
833 this = SCSI_MAX_SG_SEGMENTS - 1;
834 index = SG_MEMPOOL_NR - 1;
836 index = scsi_sgtable_index(this);
840 sgp = scsi_sg_pools + index;
843 next = sg_chain_ptr(&sgl[sgp->size - 1]);
845 mempool_free(sgl, sgp->pool);
849 * Restore original, will be freed below
851 sgl = cmd->request_buffer;
854 sgp = scsi_sg_pools + cmd->sglist_len;
855 mempool_free(sgl, sgp->pool);
858 EXPORT_SYMBOL(scsi_free_sgtable);
861 * Function: scsi_release_buffers()
863 * Purpose: Completion processing for block device I/O requests.
865 * Arguments: cmd - command that we are bailing.
867 * Lock status: Assumed that no lock is held upon entry.
871 * Notes: In the event that an upper level driver rejects a
872 * command, we must release resources allocated during
873 * the __init_io() function. Primarily this would involve
874 * the scatter-gather table, and potentially any bounce
877 static void scsi_release_buffers(struct scsi_cmnd *cmd)
880 scsi_free_sgtable(cmd);
883 * Zero these out. They now point to freed memory, and it is
884 * dangerous to hang onto the pointers.
886 cmd->request_buffer = NULL;
887 cmd->request_bufflen = 0;
891 * Function: scsi_io_completion()
893 * Purpose: Completion processing for block device I/O requests.
895 * Arguments: cmd - command that is finished.
897 * Lock status: Assumed that no lock is held upon entry.
901 * Notes: This function is matched in terms of capabilities to
902 * the function that created the scatter-gather list.
903 * In other words, if there are no bounce buffers
904 * (the normal case for most drivers), we don't need
905 * the logic to deal with cleaning up afterwards.
907 * We must do one of several things here:
909 * a) Call scsi_end_request. This will finish off the
910 * specified number of sectors. If we are done, the
911 * command block will be released, and the queue
912 * function will be goosed. If we are not done, then
913 * scsi_end_request will directly goose the queue.
915 * b) We can just use scsi_requeue_command() here. This would
916 * be used if we just wanted to retry, for example.
918 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
920 int result = cmd->result;
921 int this_count = cmd->request_bufflen;
922 struct request_queue *q = cmd->device->request_queue;
923 struct request *req = cmd->request;
924 int clear_errors = 1;
925 struct scsi_sense_hdr sshdr;
927 int sense_deferred = 0;
929 scsi_release_buffers(cmd);
932 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
934 sense_deferred = scsi_sense_is_deferred(&sshdr);
937 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
938 req->errors = result;
941 if (sense_valid && req->sense) {
943 * SG_IO wants current and deferred errors
945 int len = 8 + cmd->sense_buffer[7];
947 if (len > SCSI_SENSE_BUFFERSIZE)
948 len = SCSI_SENSE_BUFFERSIZE;
949 memcpy(req->sense, cmd->sense_buffer, len);
950 req->sense_len = len;
953 req->data_len = cmd->resid;
957 * Next deal with any sectors which we were able to correctly
960 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
962 req->nr_sectors, good_bytes));
963 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
968 /* A number of bytes were successfully read. If there
969 * are leftovers and there is some kind of error
970 * (result != 0), retry the rest.
972 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
975 /* good_bytes = 0, or (inclusive) there were leftovers and
976 * result = 0, so scsi_end_request couldn't retry.
978 if (sense_valid && !sense_deferred) {
979 switch (sshdr.sense_key) {
981 if (cmd->device->removable) {
982 /* Detected disc change. Set a bit
983 * and quietly refuse further access.
985 cmd->device->changed = 1;
986 scsi_end_request(cmd, 0, this_count, 1);
989 /* Must have been a power glitch, or a
990 * bus reset. Could not have been a
991 * media change, so we just retry the
992 * request and see what happens.
994 scsi_requeue_command(q, cmd);
998 case ILLEGAL_REQUEST:
999 /* If we had an ILLEGAL REQUEST returned, then
1000 * we may have performed an unsupported
1001 * command. The only thing this should be
1002 * would be a ten byte read where only a six
1003 * byte read was supported. Also, on a system
1004 * where READ CAPACITY failed, we may have
1005 * read past the end of the disk.
1007 if ((cmd->device->use_10_for_rw &&
1008 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
1009 (cmd->cmnd[0] == READ_10 ||
1010 cmd->cmnd[0] == WRITE_10)) {
1011 cmd->device->use_10_for_rw = 0;
1012 /* This will cause a retry with a
1015 scsi_requeue_command(q, cmd);
1018 scsi_end_request(cmd, 0, this_count, 1);
1023 /* If the device is in the process of becoming
1024 * ready, or has a temporary blockage, retry.
1026 if (sshdr.asc == 0x04) {
1027 switch (sshdr.ascq) {
1028 case 0x01: /* becoming ready */
1029 case 0x04: /* format in progress */
1030 case 0x05: /* rebuild in progress */
1031 case 0x06: /* recalculation in progress */
1032 case 0x07: /* operation in progress */
1033 case 0x08: /* Long write in progress */
1034 case 0x09: /* self test in progress */
1035 scsi_requeue_command(q, cmd);
1041 if (!(req->cmd_flags & REQ_QUIET))
1042 scsi_cmd_print_sense_hdr(cmd,
1046 scsi_end_request(cmd, 0, this_count, 1);
1048 case VOLUME_OVERFLOW:
1049 if (!(req->cmd_flags & REQ_QUIET)) {
1050 scmd_printk(KERN_INFO, cmd,
1051 "Volume overflow, CDB: ");
1052 __scsi_print_command(cmd->cmnd);
1053 scsi_print_sense("", cmd);
1055 /* See SSC3rXX or current. */
1056 scsi_end_request(cmd, 0, this_count, 1);
1062 if (host_byte(result) == DID_RESET) {
1063 /* Third party bus reset or reset for error recovery
1064 * reasons. Just retry the request and see what
1067 scsi_requeue_command(q, cmd);
1071 if (!(req->cmd_flags & REQ_QUIET)) {
1072 scsi_print_result(cmd);
1073 if (driver_byte(result) & DRIVER_SENSE)
1074 scsi_print_sense("", cmd);
1077 scsi_end_request(cmd, 0, this_count, !result);
1081 * Function: scsi_init_io()
1083 * Purpose: SCSI I/O initialize function.
1085 * Arguments: cmd - Command descriptor we wish to initialize
1087 * Returns: 0 on success
1088 * BLKPREP_DEFER if the failure is retryable
1089 * BLKPREP_KILL if the failure is fatal
1091 static int scsi_init_io(struct scsi_cmnd *cmd)
1093 struct request *req = cmd->request;
1097 * We used to not use scatter-gather for single segment request,
1098 * but now we do (it makes highmem I/O easier to support without
1101 cmd->use_sg = req->nr_phys_segments;
1104 * If sg table allocation fails, requeue request later.
1106 cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
1107 if (unlikely(!cmd->request_buffer)) {
1108 scsi_unprep_request(req);
1109 return BLKPREP_DEFER;
1113 if (blk_pc_request(req))
1114 cmd->request_bufflen = req->data_len;
1116 cmd->request_bufflen = req->nr_sectors << 9;
1119 * Next, walk the list, and fill in the addresses and sizes of
1122 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
1123 if (likely(count <= cmd->use_sg)) {
1124 cmd->use_sg = count;
1128 printk(KERN_ERR "Incorrect number of segments after building list\n");
1129 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
1130 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
1131 req->current_nr_sectors);
1133 return BLKPREP_KILL;
1136 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1137 struct request *req)
1139 struct scsi_cmnd *cmd;
1141 if (!req->special) {
1142 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1150 /* pull a tag out of the request if we have one */
1151 cmd->tag = req->tag;
1157 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1159 struct scsi_cmnd *cmd;
1160 int ret = scsi_prep_state_check(sdev, req);
1162 if (ret != BLKPREP_OK)
1165 cmd = scsi_get_cmd_from_req(sdev, req);
1167 return BLKPREP_DEFER;
1170 * BLOCK_PC requests may transfer data, in which case they must
1171 * a bio attached to them. Or they might contain a SCSI command
1172 * that does not transfer data, in which case they may optionally
1173 * submit a request without an attached bio.
1178 BUG_ON(!req->nr_phys_segments);
1180 ret = scsi_init_io(cmd);
1184 BUG_ON(req->data_len);
1187 cmd->request_bufflen = 0;
1188 cmd->request_buffer = NULL;
1193 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
1194 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1195 cmd->cmd_len = req->cmd_len;
1197 cmd->sc_data_direction = DMA_NONE;
1198 else if (rq_data_dir(req) == WRITE)
1199 cmd->sc_data_direction = DMA_TO_DEVICE;
1201 cmd->sc_data_direction = DMA_FROM_DEVICE;
1203 cmd->transfersize = req->data_len;
1204 cmd->allowed = req->retries;
1205 cmd->timeout_per_command = req->timeout;
1208 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1211 * Setup a REQ_TYPE_FS command. These are simple read/write request
1212 * from filesystems that still need to be translated to SCSI CDBs from
1215 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1217 struct scsi_cmnd *cmd;
1218 int ret = scsi_prep_state_check(sdev, req);
1220 if (ret != BLKPREP_OK)
1223 * Filesystem requests must transfer data.
1225 BUG_ON(!req->nr_phys_segments);
1227 cmd = scsi_get_cmd_from_req(sdev, req);
1229 return BLKPREP_DEFER;
1231 return scsi_init_io(cmd);
1233 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1235 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1237 int ret = BLKPREP_OK;
1240 * If the device is not in running state we will reject some
1243 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1244 switch (sdev->sdev_state) {
1247 * If the device is offline we refuse to process any
1248 * commands. The device must be brought online
1249 * before trying any recovery commands.
1251 sdev_printk(KERN_ERR, sdev,
1252 "rejecting I/O to offline device\n");
1257 * If the device is fully deleted, we refuse to
1258 * process any commands as well.
1260 sdev_printk(KERN_ERR, sdev,
1261 "rejecting I/O to dead device\n");
1267 * If the devices is blocked we defer normal commands.
1269 if (!(req->cmd_flags & REQ_PREEMPT))
1270 ret = BLKPREP_DEFER;
1274 * For any other not fully online state we only allow
1275 * special commands. In particular any user initiated
1276 * command is not allowed.
1278 if (!(req->cmd_flags & REQ_PREEMPT))
1285 EXPORT_SYMBOL(scsi_prep_state_check);
1287 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1289 struct scsi_device *sdev = q->queuedata;
1293 req->errors = DID_NO_CONNECT << 16;
1294 /* release the command and kill it */
1296 struct scsi_cmnd *cmd = req->special;
1297 scsi_release_buffers(cmd);
1298 scsi_put_command(cmd);
1299 req->special = NULL;
1304 * If we defer, the elv_next_request() returns NULL, but the
1305 * queue must be restarted, so we plug here if no returning
1306 * command will automatically do that.
1308 if (sdev->device_busy == 0)
1312 req->cmd_flags |= REQ_DONTPREP;
1317 EXPORT_SYMBOL(scsi_prep_return);
1319 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1321 struct scsi_device *sdev = q->queuedata;
1322 int ret = BLKPREP_KILL;
1324 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1325 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1326 return scsi_prep_return(q, req, ret);
1330 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1333 * Called with the queue_lock held.
1335 static inline int scsi_dev_queue_ready(struct request_queue *q,
1336 struct scsi_device *sdev)
1338 if (sdev->device_busy >= sdev->queue_depth)
1340 if (sdev->device_busy == 0 && sdev->device_blocked) {
1342 * unblock after device_blocked iterates to zero
1344 if (--sdev->device_blocked == 0) {
1346 sdev_printk(KERN_INFO, sdev,
1347 "unblocking device at zero depth\n"));
1353 if (sdev->device_blocked)
1360 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1361 * return 0. We must end up running the queue again whenever 0 is
1362 * returned, else IO can hang.
1364 * Called with host_lock held.
1366 static inline int scsi_host_queue_ready(struct request_queue *q,
1367 struct Scsi_Host *shost,
1368 struct scsi_device *sdev)
1370 if (scsi_host_in_recovery(shost))
1372 if (shost->host_busy == 0 && shost->host_blocked) {
1374 * unblock after host_blocked iterates to zero
1376 if (--shost->host_blocked == 0) {
1378 printk("scsi%d unblocking host at zero depth\n",
1385 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1386 shost->host_blocked || shost->host_self_blocked) {
1387 if (list_empty(&sdev->starved_entry))
1388 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1392 /* We're OK to process the command, so we can't be starved */
1393 if (!list_empty(&sdev->starved_entry))
1394 list_del_init(&sdev->starved_entry);
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 = cmd->device;
1406 struct Scsi_Host *shost = sdev->host;
1408 blkdev_dequeue_request(req);
1410 if (unlikely(cmd == NULL)) {
1411 printk(KERN_CRIT "impossible request in %s.\n",
1416 scsi_init_cmd_errh(cmd);
1417 cmd->result = DID_NO_CONNECT << 16;
1418 atomic_inc(&cmd->device->iorequest_cnt);
1421 * SCSI request completion path will do scsi_device_unbusy(),
1422 * bump busy counts. To bump the counters, we need to dance
1423 * with the locks as normal issue path does.
1425 sdev->device_busy++;
1426 spin_unlock(sdev->request_queue->queue_lock);
1427 spin_lock(shost->host_lock);
1429 spin_unlock(shost->host_lock);
1430 spin_lock(sdev->request_queue->queue_lock);
1435 static void scsi_softirq_done(struct request *rq)
1437 struct scsi_cmnd *cmd = rq->completion_data;
1438 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
1441 INIT_LIST_HEAD(&cmd->eh_entry);
1443 disposition = scsi_decide_disposition(cmd);
1444 if (disposition != SUCCESS &&
1445 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1446 sdev_printk(KERN_ERR, cmd->device,
1447 "timing out command, waited %lus\n",
1449 disposition = SUCCESS;
1452 scsi_log_completion(cmd, disposition);
1454 switch (disposition) {
1456 scsi_finish_command(cmd);
1459 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1461 case ADD_TO_MLQUEUE:
1462 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1465 if (!scsi_eh_scmd_add(cmd, 0))
1466 scsi_finish_command(cmd);
1471 * Function: scsi_request_fn()
1473 * Purpose: Main strategy routine for SCSI.
1475 * Arguments: q - Pointer to actual queue.
1479 * Lock status: IO request lock assumed to be held when called.
1481 static void scsi_request_fn(struct request_queue *q)
1483 struct scsi_device *sdev = q->queuedata;
1484 struct Scsi_Host *shost;
1485 struct scsi_cmnd *cmd;
1486 struct request *req;
1489 printk("scsi: killing requests for dead queue\n");
1490 while ((req = elv_next_request(q)) != NULL)
1491 scsi_kill_request(req, q);
1495 if(!get_device(&sdev->sdev_gendev))
1496 /* We must be tearing the block queue down already */
1500 * To start with, we keep looping until the queue is empty, or until
1501 * the host is no longer able to accept any more requests.
1504 while (!blk_queue_plugged(q)) {
1507 * get next queueable request. We do this early to make sure
1508 * that the request is fully prepared even if we cannot
1511 req = elv_next_request(q);
1512 if (!req || !scsi_dev_queue_ready(q, sdev))
1515 if (unlikely(!scsi_device_online(sdev))) {
1516 sdev_printk(KERN_ERR, sdev,
1517 "rejecting I/O to offline device\n");
1518 scsi_kill_request(req, q);
1524 * Remove the request from the request list.
1526 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1527 blkdev_dequeue_request(req);
1528 sdev->device_busy++;
1530 spin_unlock(q->queue_lock);
1532 if (unlikely(cmd == NULL)) {
1533 printk(KERN_CRIT "impossible request in %s.\n"
1534 "please mail a stack trace to "
1535 "linux-scsi@vger.kernel.org\n",
1537 blk_dump_rq_flags(req, "foo");
1540 spin_lock(shost->host_lock);
1542 if (!scsi_host_queue_ready(q, shost, sdev))
1544 if (sdev->single_lun) {
1545 if (scsi_target(sdev)->starget_sdev_user &&
1546 scsi_target(sdev)->starget_sdev_user != sdev)
1548 scsi_target(sdev)->starget_sdev_user = sdev;
1553 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1554 * take the lock again.
1556 spin_unlock_irq(shost->host_lock);
1559 * Finally, initialize any error handling parameters, and set up
1560 * the timers for timeouts.
1562 scsi_init_cmd_errh(cmd);
1565 * Dispatch the command to the low-level driver.
1567 rtn = scsi_dispatch_cmd(cmd);
1568 spin_lock_irq(q->queue_lock);
1570 /* we're refusing the command; because of
1571 * the way locks get dropped, we need to
1572 * check here if plugging is required */
1573 if(sdev->device_busy == 0)
1583 spin_unlock_irq(shost->host_lock);
1586 * lock q, handle tag, requeue req, and decrement device_busy. We
1587 * must return with queue_lock held.
1589 * Decrementing device_busy without checking it is OK, as all such
1590 * cases (host limits or settings) should run the queue at some
1593 spin_lock_irq(q->queue_lock);
1594 blk_requeue_request(q, req);
1595 sdev->device_busy--;
1596 if(sdev->device_busy == 0)
1599 /* must be careful here...if we trigger the ->remove() function
1600 * we cannot be holding the q lock */
1601 spin_unlock_irq(q->queue_lock);
1602 put_device(&sdev->sdev_gendev);
1603 spin_lock_irq(q->queue_lock);
1606 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1608 struct device *host_dev;
1609 u64 bounce_limit = 0xffffffff;
1611 if (shost->unchecked_isa_dma)
1612 return BLK_BOUNCE_ISA;
1614 * Platforms with virtual-DMA translation
1615 * hardware have no practical limit.
1617 if (!PCI_DMA_BUS_IS_PHYS)
1618 return BLK_BOUNCE_ANY;
1620 host_dev = scsi_get_device(shost);
1621 if (host_dev && host_dev->dma_mask)
1622 bounce_limit = *host_dev->dma_mask;
1624 return bounce_limit;
1626 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1628 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1629 request_fn_proc *request_fn)
1631 struct request_queue *q;
1633 q = blk_init_queue(request_fn, NULL);
1638 * this limit is imposed by hardware restrictions
1640 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1643 * In the future, sg chaining support will be mandatory and this
1644 * ifdef can then go away. Right now we don't have all archs
1645 * converted, so better keep it safe.
1647 #ifdef ARCH_HAS_SG_CHAIN
1648 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1650 blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
1653 blk_queue_max_sectors(q, shost->max_sectors);
1654 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1655 blk_queue_segment_boundary(q, shost->dma_boundary);
1657 if (!shost->use_clustering)
1658 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1661 EXPORT_SYMBOL(__scsi_alloc_queue);
1663 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1665 struct request_queue *q;
1667 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1671 blk_queue_prep_rq(q, scsi_prep_fn);
1672 blk_queue_softirq_done(q, scsi_softirq_done);
1676 void scsi_free_queue(struct request_queue *q)
1678 blk_cleanup_queue(q);
1682 * Function: scsi_block_requests()
1684 * Purpose: Utility function used by low-level drivers to prevent further
1685 * commands from being queued to the device.
1687 * Arguments: shost - Host in question
1691 * Lock status: No locks are assumed held.
1693 * Notes: There is no timer nor any other means by which the requests
1694 * get unblocked other than the low-level driver calling
1695 * scsi_unblock_requests().
1697 void scsi_block_requests(struct Scsi_Host *shost)
1699 shost->host_self_blocked = 1;
1701 EXPORT_SYMBOL(scsi_block_requests);
1704 * Function: scsi_unblock_requests()
1706 * Purpose: Utility function used by low-level drivers to allow further
1707 * commands from being queued to the device.
1709 * Arguments: shost - Host in question
1713 * Lock status: No locks are assumed held.
1715 * Notes: There is no timer nor any other means by which the requests
1716 * get unblocked other than the low-level driver calling
1717 * scsi_unblock_requests().
1719 * This is done as an API function so that changes to the
1720 * internals of the scsi mid-layer won't require wholesale
1721 * changes to drivers that use this feature.
1723 void scsi_unblock_requests(struct Scsi_Host *shost)
1725 shost->host_self_blocked = 0;
1726 scsi_run_host_queues(shost);
1728 EXPORT_SYMBOL(scsi_unblock_requests);
1730 int __init scsi_init_queue(void)
1734 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1735 sizeof(struct scsi_io_context),
1737 if (!scsi_io_context_cache) {
1738 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1742 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1743 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1744 int size = sgp->size * sizeof(struct scatterlist);
1746 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1747 SLAB_HWCACHE_ALIGN, NULL);
1749 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1753 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1756 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1764 void scsi_exit_queue(void)
1768 kmem_cache_destroy(scsi_io_context_cache);
1770 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1771 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1772 mempool_destroy(sgp->pool);
1773 kmem_cache_destroy(sgp->slab);
1778 * scsi_mode_select - issue a mode select
1779 * @sdev: SCSI device to be queried
1780 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1781 * @sp: Save page bit (0 == don't save, 1 == save)
1782 * @modepage: mode page being requested
1783 * @buffer: request buffer (may not be smaller than eight bytes)
1784 * @len: length of request buffer.
1785 * @timeout: command timeout
1786 * @retries: number of retries before failing
1787 * @data: returns a structure abstracting the mode header data
1788 * @sense: place to put sense data (or NULL if no sense to be collected).
1789 * must be SCSI_SENSE_BUFFERSIZE big.
1791 * Returns zero if successful; negative error number or scsi
1796 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1797 unsigned char *buffer, int len, int timeout, int retries,
1798 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1800 unsigned char cmd[10];
1801 unsigned char *real_buffer;
1804 memset(cmd, 0, sizeof(cmd));
1805 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1807 if (sdev->use_10_for_ms) {
1810 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1813 memcpy(real_buffer + 8, buffer, len);
1817 real_buffer[2] = data->medium_type;
1818 real_buffer[3] = data->device_specific;
1819 real_buffer[4] = data->longlba ? 0x01 : 0;
1821 real_buffer[6] = data->block_descriptor_length >> 8;
1822 real_buffer[7] = data->block_descriptor_length;
1824 cmd[0] = MODE_SELECT_10;
1828 if (len > 255 || data->block_descriptor_length > 255 ||
1832 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1835 memcpy(real_buffer + 4, buffer, len);
1838 real_buffer[1] = data->medium_type;
1839 real_buffer[2] = data->device_specific;
1840 real_buffer[3] = data->block_descriptor_length;
1843 cmd[0] = MODE_SELECT;
1847 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1848 sshdr, timeout, retries);
1852 EXPORT_SYMBOL_GPL(scsi_mode_select);
1855 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1856 * six bytes if necessary.
1857 * @sdev: SCSI device to be queried
1858 * @dbd: set if mode sense will allow block descriptors to be returned
1859 * @modepage: mode page being requested
1860 * @buffer: request buffer (may not be smaller than eight bytes)
1861 * @len: length of request buffer.
1862 * @timeout: command timeout
1863 * @retries: number of retries before failing
1864 * @data: returns a structure abstracting the mode header data
1865 * @sense: place to put sense data (or NULL if no sense to be collected).
1866 * must be SCSI_SENSE_BUFFERSIZE big.
1868 * Returns zero if unsuccessful, or the header offset (either 4
1869 * or 8 depending on whether a six or ten byte command was
1870 * issued) if successful.
1873 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1874 unsigned char *buffer, int len, int timeout, int retries,
1875 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1877 unsigned char cmd[12];
1881 struct scsi_sense_hdr my_sshdr;
1883 memset(data, 0, sizeof(*data));
1884 memset(&cmd[0], 0, 12);
1885 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1888 /* caller might not be interested in sense, but we need it */
1893 use_10_for_ms = sdev->use_10_for_ms;
1895 if (use_10_for_ms) {
1899 cmd[0] = MODE_SENSE_10;
1906 cmd[0] = MODE_SENSE;
1911 memset(buffer, 0, len);
1913 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1914 sshdr, timeout, retries);
1916 /* This code looks awful: what it's doing is making sure an
1917 * ILLEGAL REQUEST sense return identifies the actual command
1918 * byte as the problem. MODE_SENSE commands can return
1919 * ILLEGAL REQUEST if the code page isn't supported */
1921 if (use_10_for_ms && !scsi_status_is_good(result) &&
1922 (driver_byte(result) & DRIVER_SENSE)) {
1923 if (scsi_sense_valid(sshdr)) {
1924 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1925 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1927 * Invalid command operation code
1929 sdev->use_10_for_ms = 0;
1935 if(scsi_status_is_good(result)) {
1936 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1937 (modepage == 6 || modepage == 8))) {
1938 /* Initio breakage? */
1941 data->medium_type = 0;
1942 data->device_specific = 0;
1944 data->block_descriptor_length = 0;
1945 } else if(use_10_for_ms) {
1946 data->length = buffer[0]*256 + buffer[1] + 2;
1947 data->medium_type = buffer[2];
1948 data->device_specific = buffer[3];
1949 data->longlba = buffer[4] & 0x01;
1950 data->block_descriptor_length = buffer[6]*256
1953 data->length = buffer[0] + 1;
1954 data->medium_type = buffer[1];
1955 data->device_specific = buffer[2];
1956 data->block_descriptor_length = buffer[3];
1958 data->header_length = header_length;
1963 EXPORT_SYMBOL(scsi_mode_sense);
1966 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1969 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1971 struct scsi_sense_hdr sshdr;
1974 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
1977 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
1979 if ((scsi_sense_valid(&sshdr)) &&
1980 ((sshdr.sense_key == UNIT_ATTENTION) ||
1981 (sshdr.sense_key == NOT_READY))) {
1988 EXPORT_SYMBOL(scsi_test_unit_ready);
1991 * scsi_device_set_state - Take the given device through the device
1993 * @sdev: scsi device to change the state of.
1994 * @state: state to change to.
1996 * Returns zero if unsuccessful or an error if the requested
1997 * transition is illegal.
2000 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2002 enum scsi_device_state oldstate = sdev->sdev_state;
2004 if (state == oldstate)
2009 /* There are no legal states that come back to
2010 * created. This is the manually initialised start
2084 sdev->sdev_state = state;
2088 SCSI_LOG_ERROR_RECOVERY(1,
2089 sdev_printk(KERN_ERR, sdev,
2090 "Illegal state transition %s->%s\n",
2091 scsi_device_state_name(oldstate),
2092 scsi_device_state_name(state))
2096 EXPORT_SYMBOL(scsi_device_set_state);
2099 * scsi_device_quiesce - Block user issued commands.
2100 * @sdev: scsi device to quiesce.
2102 * This works by trying to transition to the SDEV_QUIESCE state
2103 * (which must be a legal transition). When the device is in this
2104 * state, only special requests will be accepted, all others will
2105 * be deferred. Since special requests may also be requeued requests,
2106 * a successful return doesn't guarantee the device will be
2107 * totally quiescent.
2109 * Must be called with user context, may sleep.
2111 * Returns zero if unsuccessful or an error if not.
2114 scsi_device_quiesce(struct scsi_device *sdev)
2116 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2120 scsi_run_queue(sdev->request_queue);
2121 while (sdev->device_busy) {
2122 msleep_interruptible(200);
2123 scsi_run_queue(sdev->request_queue);
2127 EXPORT_SYMBOL(scsi_device_quiesce);
2130 * scsi_device_resume - Restart user issued commands to a quiesced device.
2131 * @sdev: scsi device to resume.
2133 * Moves the device from quiesced back to running and restarts the
2136 * Must be called with user context, may sleep.
2139 scsi_device_resume(struct scsi_device *sdev)
2141 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2143 scsi_run_queue(sdev->request_queue);
2145 EXPORT_SYMBOL(scsi_device_resume);
2148 device_quiesce_fn(struct scsi_device *sdev, void *data)
2150 scsi_device_quiesce(sdev);
2154 scsi_target_quiesce(struct scsi_target *starget)
2156 starget_for_each_device(starget, NULL, device_quiesce_fn);
2158 EXPORT_SYMBOL(scsi_target_quiesce);
2161 device_resume_fn(struct scsi_device *sdev, void *data)
2163 scsi_device_resume(sdev);
2167 scsi_target_resume(struct scsi_target *starget)
2169 starget_for_each_device(starget, NULL, device_resume_fn);
2171 EXPORT_SYMBOL(scsi_target_resume);
2174 * scsi_internal_device_block - internal function to put a device
2175 * temporarily into the SDEV_BLOCK state
2176 * @sdev: device to block
2178 * Block request made by scsi lld's to temporarily stop all
2179 * scsi commands on the specified device. Called from interrupt
2180 * or normal process context.
2182 * Returns zero if successful or error if not
2185 * This routine transitions the device to the SDEV_BLOCK state
2186 * (which must be a legal transition). When the device is in this
2187 * state, all commands are deferred until the scsi lld reenables
2188 * the device with scsi_device_unblock or device_block_tmo fires.
2189 * This routine assumes the host_lock is held on entry.
2192 scsi_internal_device_block(struct scsi_device *sdev)
2194 struct request_queue *q = sdev->request_queue;
2195 unsigned long flags;
2198 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2203 * The device has transitioned to SDEV_BLOCK. Stop the
2204 * block layer from calling the midlayer with this device's
2207 spin_lock_irqsave(q->queue_lock, flags);
2209 spin_unlock_irqrestore(q->queue_lock, flags);
2213 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2216 * scsi_internal_device_unblock - resume a device after a block request
2217 * @sdev: device to resume
2219 * Called by scsi lld's or the midlayer to restart the device queue
2220 * for the previously suspended scsi device. Called from interrupt or
2221 * normal process context.
2223 * Returns zero if successful or error if not.
2226 * This routine transitions the device to the SDEV_RUNNING state
2227 * (which must be a legal transition) allowing the midlayer to
2228 * goose the queue for this device. This routine assumes the
2229 * host_lock is held upon entry.
2232 scsi_internal_device_unblock(struct scsi_device *sdev)
2234 struct request_queue *q = sdev->request_queue;
2236 unsigned long flags;
2239 * Try to transition the scsi device to SDEV_RUNNING
2240 * and goose the device queue if successful.
2242 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2246 spin_lock_irqsave(q->queue_lock, flags);
2248 spin_unlock_irqrestore(q->queue_lock, flags);
2252 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2255 device_block(struct scsi_device *sdev, void *data)
2257 scsi_internal_device_block(sdev);
2261 target_block(struct device *dev, void *data)
2263 if (scsi_is_target_device(dev))
2264 starget_for_each_device(to_scsi_target(dev), NULL,
2270 scsi_target_block(struct device *dev)
2272 if (scsi_is_target_device(dev))
2273 starget_for_each_device(to_scsi_target(dev), NULL,
2276 device_for_each_child(dev, NULL, target_block);
2278 EXPORT_SYMBOL_GPL(scsi_target_block);
2281 device_unblock(struct scsi_device *sdev, void *data)
2283 scsi_internal_device_unblock(sdev);
2287 target_unblock(struct device *dev, void *data)
2289 if (scsi_is_target_device(dev))
2290 starget_for_each_device(to_scsi_target(dev), NULL,
2296 scsi_target_unblock(struct device *dev)
2298 if (scsi_is_target_device(dev))
2299 starget_for_each_device(to_scsi_target(dev), NULL,
2302 device_for_each_child(dev, NULL, target_unblock);
2304 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2307 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2308 * @sg: scatter-gather list
2309 * @sg_count: number of segments in sg
2310 * @offset: offset in bytes into sg, on return offset into the mapped area
2311 * @len: bytes to map, on return number of bytes mapped
2313 * Returns virtual address of the start of the mapped page
2315 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2316 size_t *offset, size_t *len)
2319 size_t sg_len = 0, len_complete = 0;
2320 struct scatterlist *sg;
2323 WARN_ON(!irqs_disabled());
2325 for_each_sg(sgl, sg, sg_count, i) {
2326 len_complete = sg_len; /* Complete sg-entries */
2327 sg_len += sg->length;
2328 if (sg_len > *offset)
2332 if (unlikely(i == sg_count)) {
2333 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2335 __FUNCTION__, sg_len, *offset, sg_count);
2340 /* Offset starting from the beginning of first page in this sg-entry */
2341 *offset = *offset - len_complete + sg->offset;
2343 /* Assumption: contiguous pages can be accessed as "page + i" */
2344 page = nth_page(sg->page, (*offset >> PAGE_SHIFT));
2345 *offset &= ~PAGE_MASK;
2347 /* Bytes in this sg-entry from *offset to the end of the page */
2348 sg_len = PAGE_SIZE - *offset;
2352 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2354 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2357 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously
2358 * mapped with scsi_kmap_atomic_sg
2359 * @virt: virtual address to be unmapped
2361 void scsi_kunmap_atomic_sg(void *virt)
2363 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2365 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);