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>
21 #include <scsi/scsi.h>
22 #include <scsi/scsi_cmnd.h>
23 #include <scsi/scsi_dbg.h>
24 #include <scsi/scsi_device.h>
25 #include <scsi/scsi_driver.h>
26 #include <scsi/scsi_eh.h>
27 #include <scsi/scsi_host.h>
29 #include "scsi_priv.h"
30 #include "scsi_logging.h"
33 #define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
34 #define SG_MEMPOOL_SIZE 32
36 struct scsi_host_sg_pool {
39 struct kmem_cache *slab;
43 #if (SCSI_MAX_PHYS_SEGMENTS < 32)
44 #error SCSI_MAX_PHYS_SEGMENTS is too small
47 #define SP(x) { x, "sgpool-" #x }
48 static struct scsi_host_sg_pool scsi_sg_pools[] = {
52 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
54 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
56 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
58 #if (SCSI_MAX_PHYS_SEGMENTS > 256)
59 #error SCSI_MAX_PHYS_SEGMENTS is too large
67 static void scsi_run_queue(struct request_queue *q);
70 * Function: scsi_unprep_request()
72 * Purpose: Remove all preparation done for a request, including its
73 * associated scsi_cmnd, so that it can be requeued.
75 * Arguments: req - request to unprepare
77 * Lock status: Assumed that no locks are held upon entry.
81 static void scsi_unprep_request(struct request *req)
83 struct scsi_cmnd *cmd = req->special;
85 req->cmd_flags &= ~REQ_DONTPREP;
88 scsi_put_command(cmd);
92 * Function: scsi_queue_insert()
94 * Purpose: Insert a command in the midlevel queue.
96 * Arguments: cmd - command that we are adding to queue.
97 * reason - why we are inserting command to queue.
99 * Lock status: Assumed that lock is not held upon entry.
103 * Notes: We do this for one of two cases. Either the host is busy
104 * and it cannot accept any more commands for the time being,
105 * or the device returned QUEUE_FULL and can accept no more
107 * Notes: This could be called either from an interrupt context or a
108 * normal process context.
110 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
112 struct Scsi_Host *host = cmd->device->host;
113 struct scsi_device *device = cmd->device;
114 struct request_queue *q = device->request_queue;
118 printk("Inserting command %p into mlqueue\n", cmd));
121 * Set the appropriate busy bit for the device/host.
123 * If the host/device isn't busy, assume that something actually
124 * completed, and that we should be able to queue a command now.
126 * Note that the prior mid-layer assumption that any host could
127 * always queue at least one command is now broken. The mid-layer
128 * will implement a user specifiable stall (see
129 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
130 * if a command is requeued with no other commands outstanding
131 * either for the device or for the host.
133 if (reason == SCSI_MLQUEUE_HOST_BUSY)
134 host->host_blocked = host->max_host_blocked;
135 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
136 device->device_blocked = device->max_device_blocked;
139 * Decrement the counters, since these commands are no longer
140 * active on the host/device.
142 scsi_device_unbusy(device);
145 * Requeue this command. It will go before all other commands
146 * that are already in the queue.
148 * NOTE: there is magic here about the way the queue is plugged if
149 * we have no outstanding commands.
151 * Although we *don't* plug the queue, we call the request
152 * function. The SCSI request function detects the blocked condition
153 * and plugs the queue appropriately.
155 spin_lock_irqsave(q->queue_lock, flags);
156 blk_requeue_request(q, cmd->request);
157 spin_unlock_irqrestore(q->queue_lock, flags);
165 * scsi_execute - insert request and wait for the result
168 * @data_direction: data direction
169 * @buffer: data buffer
170 * @bufflen: len of buffer
171 * @sense: optional sense buffer
172 * @timeout: request timeout in seconds
173 * @retries: number of times to retry request
174 * @flags: or into request flags;
176 * returns the req->errors value which is the the scsi_cmnd result
179 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
180 int data_direction, void *buffer, unsigned bufflen,
181 unsigned char *sense, int timeout, int retries, int flags)
184 int write = (data_direction == DMA_TO_DEVICE);
185 int ret = DRIVER_ERROR << 24;
187 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
189 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
190 buffer, bufflen, __GFP_WAIT))
193 req->cmd_len = COMMAND_SIZE(cmd[0]);
194 memcpy(req->cmd, cmd, req->cmd_len);
197 req->retries = retries;
198 req->timeout = timeout;
199 req->cmd_type = REQ_TYPE_BLOCK_PC;
200 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
203 * head injection *required* here otherwise quiesce won't work
205 blk_execute_rq(req->q, NULL, req, 1);
209 blk_put_request(req);
213 EXPORT_SYMBOL(scsi_execute);
216 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
217 int data_direction, void *buffer, unsigned bufflen,
218 struct scsi_sense_hdr *sshdr, int timeout, int retries)
224 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
226 return DRIVER_ERROR << 24;
228 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
229 sense, timeout, retries, 0);
231 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
236 EXPORT_SYMBOL(scsi_execute_req);
238 struct scsi_io_context {
240 void (*done)(void *data, char *sense, int result, int resid);
241 char sense[SCSI_SENSE_BUFFERSIZE];
244 static struct kmem_cache *scsi_io_context_cache;
246 static void scsi_end_async(struct request *req, int uptodate)
248 struct scsi_io_context *sioc = req->end_io_data;
251 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
253 kmem_cache_free(scsi_io_context_cache, sioc);
254 __blk_put_request(req->q, req);
257 static int scsi_merge_bio(struct request *rq, struct bio *bio)
259 struct request_queue *q = rq->q;
261 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
262 if (rq_data_dir(rq) == WRITE)
263 bio->bi_rw |= (1 << BIO_RW);
264 blk_queue_bounce(q, &bio);
267 blk_rq_bio_prep(q, rq, bio);
268 else if (!ll_back_merge_fn(q, rq, bio))
271 rq->biotail->bi_next = bio;
278 static int scsi_bi_endio(struct bio *bio, unsigned int bytes_done, int error)
288 * scsi_req_map_sg - map a scatterlist into a request
289 * @rq: request to fill
291 * @nsegs: number of elements
292 * @bufflen: len of buffer
293 * @gfp: memory allocation flags
295 * scsi_req_map_sg maps a scatterlist into a request so that the
296 * request can be sent to the block layer. We do not trust the scatterlist
297 * sent to use, as some ULDs use that struct to only organize the pages.
299 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
300 int nsegs, unsigned bufflen, gfp_t gfp)
302 struct request_queue *q = rq->q;
303 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
304 unsigned int data_len = 0, len, bytes, off;
306 struct bio *bio = NULL;
307 int i, err, nr_vecs = 0;
309 for (i = 0; i < nsegs; i++) {
316 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
319 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
322 bio = bio_alloc(gfp, nr_vecs);
327 bio->bi_end_io = scsi_bi_endio;
330 if (bio_add_pc_page(q, bio, page, bytes, off) !=
337 if (bio->bi_vcnt >= nr_vecs) {
338 err = scsi_merge_bio(rq, bio);
340 bio_endio(bio, bio->bi_size, 0);
352 rq->buffer = rq->data = NULL;
353 rq->data_len = data_len;
357 while ((bio = rq->bio) != NULL) {
358 rq->bio = bio->bi_next;
360 * call endio instead of bio_put incase it was bounced
362 bio_endio(bio, bio->bi_size, 0);
369 * scsi_execute_async - insert request
372 * @cmd_len: length of scsi cdb
373 * @data_direction: data direction
374 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
375 * @bufflen: len of buffer
376 * @use_sg: if buffer is a scatterlist this is the number of elements
377 * @timeout: request timeout in seconds
378 * @retries: number of times to retry request
379 * @flags: or into request flags
381 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
382 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
383 int use_sg, int timeout, int retries, void *privdata,
384 void (*done)(void *, char *, int, int), gfp_t gfp)
387 struct scsi_io_context *sioc;
389 int write = (data_direction == DMA_TO_DEVICE);
391 sioc = kmem_cache_alloc(scsi_io_context_cache, gfp);
393 return DRIVER_ERROR << 24;
394 memset(sioc, 0, sizeof(*sioc));
396 req = blk_get_request(sdev->request_queue, write, gfp);
399 req->cmd_type = REQ_TYPE_BLOCK_PC;
400 req->cmd_flags |= REQ_QUIET;
403 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
405 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
410 req->cmd_len = cmd_len;
411 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
412 memcpy(req->cmd, cmd, req->cmd_len);
413 req->sense = sioc->sense;
415 req->timeout = timeout;
416 req->retries = retries;
417 req->end_io_data = sioc;
419 sioc->data = privdata;
422 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
426 blk_put_request(req);
428 kmem_cache_free(scsi_io_context_cache, sioc);
429 return DRIVER_ERROR << 24;
431 EXPORT_SYMBOL_GPL(scsi_execute_async);
434 * Function: scsi_init_cmd_errh()
436 * Purpose: Initialize cmd fields related to error handling.
438 * Arguments: cmd - command that is ready to be queued.
440 * Notes: This function has the job of initializing a number of
441 * fields related to error handling. Typically this will
442 * be called once for each command, as required.
444 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
446 cmd->serial_number = 0;
447 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
448 if (cmd->cmd_len == 0)
449 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
452 void scsi_device_unbusy(struct scsi_device *sdev)
454 struct Scsi_Host *shost = sdev->host;
457 spin_lock_irqsave(shost->host_lock, flags);
459 if (unlikely(scsi_host_in_recovery(shost) &&
460 (shost->host_failed || shost->host_eh_scheduled)))
461 scsi_eh_wakeup(shost);
462 spin_unlock(shost->host_lock);
463 spin_lock(sdev->request_queue->queue_lock);
465 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
469 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
470 * and call blk_run_queue for all the scsi_devices on the target -
471 * including current_sdev first.
473 * Called with *no* scsi locks held.
475 static void scsi_single_lun_run(struct scsi_device *current_sdev)
477 struct Scsi_Host *shost = current_sdev->host;
478 struct scsi_device *sdev, *tmp;
479 struct scsi_target *starget = scsi_target(current_sdev);
482 spin_lock_irqsave(shost->host_lock, flags);
483 starget->starget_sdev_user = NULL;
484 spin_unlock_irqrestore(shost->host_lock, flags);
487 * Call blk_run_queue for all LUNs on the target, starting with
488 * current_sdev. We race with others (to set starget_sdev_user),
489 * but in most cases, we will be first. Ideally, each LU on the
490 * target would get some limited time or requests on the target.
492 blk_run_queue(current_sdev->request_queue);
494 spin_lock_irqsave(shost->host_lock, flags);
495 if (starget->starget_sdev_user)
497 list_for_each_entry_safe(sdev, tmp, &starget->devices,
498 same_target_siblings) {
499 if (sdev == current_sdev)
501 if (scsi_device_get(sdev))
504 spin_unlock_irqrestore(shost->host_lock, flags);
505 blk_run_queue(sdev->request_queue);
506 spin_lock_irqsave(shost->host_lock, flags);
508 scsi_device_put(sdev);
511 spin_unlock_irqrestore(shost->host_lock, flags);
515 * Function: scsi_run_queue()
517 * Purpose: Select a proper request queue to serve next
519 * Arguments: q - last request's queue
523 * Notes: The previous command was completely finished, start
524 * a new one if possible.
526 static void scsi_run_queue(struct request_queue *q)
528 struct scsi_device *sdev = q->queuedata;
529 struct Scsi_Host *shost = sdev->host;
532 if (sdev->single_lun)
533 scsi_single_lun_run(sdev);
535 spin_lock_irqsave(shost->host_lock, flags);
536 while (!list_empty(&shost->starved_list) &&
537 !shost->host_blocked && !shost->host_self_blocked &&
538 !((shost->can_queue > 0) &&
539 (shost->host_busy >= shost->can_queue))) {
541 * As long as shost is accepting commands and we have
542 * starved queues, call blk_run_queue. scsi_request_fn
543 * drops the queue_lock and can add us back to the
546 * host_lock protects the starved_list and starved_entry.
547 * scsi_request_fn must get the host_lock before checking
548 * or modifying starved_list or starved_entry.
550 sdev = list_entry(shost->starved_list.next,
551 struct scsi_device, starved_entry);
552 list_del_init(&sdev->starved_entry);
553 spin_unlock_irqrestore(shost->host_lock, flags);
556 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
557 !test_and_set_bit(QUEUE_FLAG_REENTER,
558 &sdev->request_queue->queue_flags)) {
559 blk_run_queue(sdev->request_queue);
560 clear_bit(QUEUE_FLAG_REENTER,
561 &sdev->request_queue->queue_flags);
563 blk_run_queue(sdev->request_queue);
565 spin_lock_irqsave(shost->host_lock, flags);
566 if (unlikely(!list_empty(&sdev->starved_entry)))
568 * sdev lost a race, and was put back on the
569 * starved list. This is unlikely but without this
570 * in theory we could loop forever.
574 spin_unlock_irqrestore(shost->host_lock, flags);
580 * Function: scsi_requeue_command()
582 * Purpose: Handle post-processing of completed commands.
584 * Arguments: q - queue to operate on
585 * cmd - command that may need to be requeued.
589 * Notes: After command completion, there may be blocks left
590 * over which weren't finished by the previous command
591 * this can be for a number of reasons - the main one is
592 * I/O errors in the middle of the request, in which case
593 * we need to request the blocks that come after the bad
595 * Notes: Upon return, cmd is a stale pointer.
597 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
599 struct request *req = cmd->request;
602 scsi_unprep_request(req);
603 spin_lock_irqsave(q->queue_lock, flags);
604 blk_requeue_request(q, req);
605 spin_unlock_irqrestore(q->queue_lock, flags);
610 void scsi_next_command(struct scsi_cmnd *cmd)
612 struct scsi_device *sdev = cmd->device;
613 struct request_queue *q = sdev->request_queue;
615 /* need to hold a reference on the device before we let go of the cmd */
616 get_device(&sdev->sdev_gendev);
618 scsi_put_command(cmd);
621 /* ok to remove device now */
622 put_device(&sdev->sdev_gendev);
625 void scsi_run_host_queues(struct Scsi_Host *shost)
627 struct scsi_device *sdev;
629 shost_for_each_device(sdev, shost)
630 scsi_run_queue(sdev->request_queue);
634 * Function: scsi_end_request()
636 * Purpose: Post-processing of completed commands (usually invoked at end
637 * of upper level post-processing and scsi_io_completion).
639 * Arguments: cmd - command that is complete.
640 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
641 * bytes - number of bytes of completed I/O
642 * requeue - indicates whether we should requeue leftovers.
644 * Lock status: Assumed that lock is not held upon entry.
646 * Returns: cmd if requeue required, NULL otherwise.
648 * Notes: This is called for block device requests in order to
649 * mark some number of sectors as complete.
651 * We are guaranteeing that the request queue will be goosed
652 * at some point during this call.
653 * Notes: If cmd was requeued, upon return it will be a stale pointer.
655 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
656 int bytes, int requeue)
658 request_queue_t *q = cmd->device->request_queue;
659 struct request *req = cmd->request;
663 * If there are blocks left over at the end, set up the command
664 * to queue the remainder of them.
666 if (end_that_request_chunk(req, uptodate, bytes)) {
667 int leftover = (req->hard_nr_sectors << 9);
669 if (blk_pc_request(req))
670 leftover = req->data_len;
672 /* kill remainder if no retrys */
673 if (!uptodate && blk_noretry_request(req))
674 end_that_request_chunk(req, 0, leftover);
678 * Bleah. Leftovers again. Stick the
679 * leftovers in the front of the
680 * queue, and goose the queue again.
682 scsi_requeue_command(q, cmd);
689 add_disk_randomness(req->rq_disk);
691 spin_lock_irqsave(q->queue_lock, flags);
692 if (blk_rq_tagged(req))
693 blk_queue_end_tag(q, req);
694 end_that_request_last(req, uptodate);
695 spin_unlock_irqrestore(q->queue_lock, flags);
698 * This will goose the queue request function at the end, so we don't
699 * need to worry about launching another command.
701 scsi_next_command(cmd);
705 struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
707 struct scsi_host_sg_pool *sgp;
708 struct scatterlist *sgl;
710 BUG_ON(!cmd->use_sg);
712 switch (cmd->use_sg) {
722 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
726 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
730 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
741 sgp = scsi_sg_pools + cmd->sglist_len;
742 sgl = mempool_alloc(sgp->pool, gfp_mask);
746 EXPORT_SYMBOL(scsi_alloc_sgtable);
748 void scsi_free_sgtable(struct scatterlist *sgl, int index)
750 struct scsi_host_sg_pool *sgp;
752 BUG_ON(index >= SG_MEMPOOL_NR);
754 sgp = scsi_sg_pools + index;
755 mempool_free(sgl, sgp->pool);
758 EXPORT_SYMBOL(scsi_free_sgtable);
761 * Function: scsi_release_buffers()
763 * Purpose: Completion processing for block device I/O requests.
765 * Arguments: cmd - command that we are bailing.
767 * Lock status: Assumed that no lock is held upon entry.
771 * Notes: In the event that an upper level driver rejects a
772 * command, we must release resources allocated during
773 * the __init_io() function. Primarily this would involve
774 * the scatter-gather table, and potentially any bounce
777 static void scsi_release_buffers(struct scsi_cmnd *cmd)
780 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
783 * Zero these out. They now point to freed memory, and it is
784 * dangerous to hang onto the pointers.
786 cmd->request_buffer = NULL;
787 cmd->request_bufflen = 0;
791 * Function: scsi_io_completion()
793 * Purpose: Completion processing for block device I/O requests.
795 * Arguments: cmd - command that is finished.
797 * Lock status: Assumed that no lock is held upon entry.
801 * Notes: This function is matched in terms of capabilities to
802 * the function that created the scatter-gather list.
803 * In other words, if there are no bounce buffers
804 * (the normal case for most drivers), we don't need
805 * the logic to deal with cleaning up afterwards.
807 * We must do one of several things here:
809 * a) Call scsi_end_request. This will finish off the
810 * specified number of sectors. If we are done, the
811 * command block will be released, and the queue
812 * function will be goosed. If we are not done, then
813 * scsi_end_request will directly goose the queue.
815 * b) We can just use scsi_requeue_command() here. This would
816 * be used if we just wanted to retry, for example.
818 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
820 int result = cmd->result;
821 int this_count = cmd->request_bufflen;
822 request_queue_t *q = cmd->device->request_queue;
823 struct request *req = cmd->request;
824 int clear_errors = 1;
825 struct scsi_sense_hdr sshdr;
827 int sense_deferred = 0;
829 scsi_release_buffers(cmd);
832 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
834 sense_deferred = scsi_sense_is_deferred(&sshdr);
837 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
838 req->errors = result;
841 if (sense_valid && req->sense) {
843 * SG_IO wants current and deferred errors
845 int len = 8 + cmd->sense_buffer[7];
847 if (len > SCSI_SENSE_BUFFERSIZE)
848 len = SCSI_SENSE_BUFFERSIZE;
849 memcpy(req->sense, cmd->sense_buffer, len);
850 req->sense_len = len;
853 req->data_len = cmd->resid;
857 * Next deal with any sectors which we were able to correctly
860 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
862 req->nr_sectors, good_bytes));
863 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
868 /* A number of bytes were successfully read. If there
869 * are leftovers and there is some kind of error
870 * (result != 0), retry the rest.
872 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
875 /* good_bytes = 0, or (inclusive) there were leftovers and
876 * result = 0, so scsi_end_request couldn't retry.
878 if (sense_valid && !sense_deferred) {
879 switch (sshdr.sense_key) {
881 if (cmd->device->removable) {
882 /* Detected disc change. Set a bit
883 * and quietly refuse further access.
885 cmd->device->changed = 1;
886 scsi_end_request(cmd, 0, this_count, 1);
889 /* Must have been a power glitch, or a
890 * bus reset. Could not have been a
891 * media change, so we just retry the
892 * request and see what happens.
894 scsi_requeue_command(q, cmd);
898 case ILLEGAL_REQUEST:
899 /* If we had an ILLEGAL REQUEST returned, then
900 * we may have performed an unsupported
901 * command. The only thing this should be
902 * would be a ten byte read where only a six
903 * byte read was supported. Also, on a system
904 * where READ CAPACITY failed, we may have
905 * read past the end of the disk.
907 if ((cmd->device->use_10_for_rw &&
908 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
909 (cmd->cmnd[0] == READ_10 ||
910 cmd->cmnd[0] == WRITE_10)) {
911 cmd->device->use_10_for_rw = 0;
912 /* This will cause a retry with a
915 scsi_requeue_command(q, cmd);
918 scsi_end_request(cmd, 0, this_count, 1);
923 /* If the device is in the process of becoming
924 * ready, or has a temporary blockage, retry.
926 if (sshdr.asc == 0x04) {
927 switch (sshdr.ascq) {
928 case 0x01: /* becoming ready */
929 case 0x04: /* format in progress */
930 case 0x05: /* rebuild in progress */
931 case 0x06: /* recalculation in progress */
932 case 0x07: /* operation in progress */
933 case 0x08: /* Long write in progress */
934 case 0x09: /* self test in progress */
935 scsi_requeue_command(q, cmd);
941 if (!(req->cmd_flags & REQ_QUIET)) {
942 scmd_printk(KERN_INFO, cmd,
943 "Device not ready: ");
944 scsi_print_sense_hdr("", &sshdr);
946 scsi_end_request(cmd, 0, this_count, 1);
948 case VOLUME_OVERFLOW:
949 if (!(req->cmd_flags & REQ_QUIET)) {
950 scmd_printk(KERN_INFO, cmd,
951 "Volume overflow, CDB: ");
952 __scsi_print_command(cmd->cmnd);
953 scsi_print_sense("", cmd);
955 /* See SSC3rXX or current. */
956 scsi_end_request(cmd, 0, this_count, 1);
962 if (host_byte(result) == DID_RESET) {
963 /* Third party bus reset or reset for error recovery
964 * reasons. Just retry the request and see what
967 scsi_requeue_command(q, cmd);
971 if (!(req->cmd_flags & REQ_QUIET)) {
972 scmd_printk(KERN_INFO, cmd,
973 "SCSI error: return code = 0x%08x\n",
975 if (driver_byte(result) & DRIVER_SENSE)
976 scsi_print_sense("", cmd);
979 scsi_end_request(cmd, 0, this_count, !result);
981 EXPORT_SYMBOL(scsi_io_completion);
984 * Function: scsi_init_io()
986 * Purpose: SCSI I/O initialize function.
988 * Arguments: cmd - Command descriptor we wish to initialize
990 * Returns: 0 on success
991 * BLKPREP_DEFER if the failure is retryable
992 * BLKPREP_KILL if the failure is fatal
994 static int scsi_init_io(struct scsi_cmnd *cmd)
996 struct request *req = cmd->request;
997 struct scatterlist *sgpnt;
1001 * We used to not use scatter-gather for single segment request,
1002 * but now we do (it makes highmem I/O easier to support without
1005 cmd->use_sg = req->nr_phys_segments;
1008 * If sg table allocation fails, requeue request later.
1010 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
1011 if (unlikely(!sgpnt)) {
1012 scsi_unprep_request(req);
1013 return BLKPREP_DEFER;
1017 cmd->request_buffer = (char *) sgpnt;
1018 if (blk_pc_request(req))
1019 cmd->request_bufflen = req->data_len;
1021 cmd->request_bufflen = req->nr_sectors << 9;
1024 * Next, walk the list, and fill in the addresses and sizes of
1027 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
1028 if (likely(count <= cmd->use_sg)) {
1029 cmd->use_sg = count;
1033 printk(KERN_ERR "Incorrect number of segments after building list\n");
1034 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
1035 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
1036 req->current_nr_sectors);
1038 /* release the command and kill it */
1039 scsi_release_buffers(cmd);
1040 scsi_put_command(cmd);
1041 return BLKPREP_KILL;
1044 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1045 sector_t *error_sector)
1047 struct scsi_device *sdev = q->queuedata;
1048 struct scsi_driver *drv;
1050 if (sdev->sdev_state != SDEV_RUNNING)
1053 drv = *(struct scsi_driver **) disk->private_data;
1054 if (drv->issue_flush)
1055 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1060 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1061 struct request *req)
1063 struct scsi_cmnd *cmd;
1065 if (!req->special) {
1066 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1074 /* pull a tag out of the request if we have one */
1075 cmd->tag = req->tag;
1081 static void scsi_blk_pc_done(struct scsi_cmnd *cmd)
1083 BUG_ON(!blk_pc_request(cmd->request));
1085 * This will complete the whole command with uptodate=1 so
1086 * as far as the block layer is concerned the command completed
1087 * successfully. Since this is a REQ_BLOCK_PC command the
1088 * caller should check the request's errors value
1090 scsi_io_completion(cmd, cmd->request_bufflen);
1093 static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1095 struct scsi_cmnd *cmd;
1097 cmd = scsi_get_cmd_from_req(sdev, req);
1099 return BLKPREP_DEFER;
1102 * BLOCK_PC requests may transfer data, in which case they must
1103 * a bio attached to them. Or they might contain a SCSI command
1104 * that does not transfer data, in which case they may optionally
1105 * submit a request without an attached bio.
1110 BUG_ON(!req->nr_phys_segments);
1112 ret = scsi_init_io(cmd);
1116 BUG_ON(req->data_len);
1119 cmd->request_bufflen = 0;
1120 cmd->request_buffer = NULL;
1125 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
1126 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1127 cmd->cmd_len = req->cmd_len;
1129 cmd->sc_data_direction = DMA_NONE;
1130 else if (rq_data_dir(req) == WRITE)
1131 cmd->sc_data_direction = DMA_TO_DEVICE;
1133 cmd->sc_data_direction = DMA_FROM_DEVICE;
1135 cmd->transfersize = req->data_len;
1136 cmd->allowed = req->retries;
1137 cmd->timeout_per_command = req->timeout;
1138 cmd->done = scsi_blk_pc_done;
1143 * Setup a REQ_TYPE_FS command. These are simple read/write request
1144 * from filesystems that still need to be translated to SCSI CDBs from
1147 static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1149 struct scsi_cmnd *cmd;
1150 struct scsi_driver *drv;
1154 * Filesystem requests must transfer data.
1156 BUG_ON(!req->nr_phys_segments);
1158 cmd = scsi_get_cmd_from_req(sdev, req);
1160 return BLKPREP_DEFER;
1162 ret = scsi_init_io(cmd);
1167 * Initialize the actual SCSI command for this request.
1169 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1170 if (unlikely(!drv->init_command(cmd))) {
1171 scsi_release_buffers(cmd);
1172 scsi_put_command(cmd);
1173 return BLKPREP_KILL;
1179 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1181 struct scsi_device *sdev = q->queuedata;
1182 int ret = BLKPREP_OK;
1185 * If the device is not in running state we will reject some
1188 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1189 switch (sdev->sdev_state) {
1192 * If the device is offline we refuse to process any
1193 * commands. The device must be brought online
1194 * before trying any recovery commands.
1196 sdev_printk(KERN_ERR, sdev,
1197 "rejecting I/O to offline device\n");
1202 * If the device is fully deleted, we refuse to
1203 * process any commands as well.
1205 sdev_printk(KERN_ERR, sdev,
1206 "rejecting I/O to dead device\n");
1212 * If the devices is blocked we defer normal commands.
1214 if (!(req->cmd_flags & REQ_PREEMPT))
1215 ret = BLKPREP_DEFER;
1219 * For any other not fully online state we only allow
1220 * special commands. In particular any user initiated
1221 * command is not allowed.
1223 if (!(req->cmd_flags & REQ_PREEMPT))
1228 if (ret != BLKPREP_OK)
1232 switch (req->cmd_type) {
1233 case REQ_TYPE_BLOCK_PC:
1234 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1237 ret = scsi_setup_fs_cmnd(sdev, req);
1241 * All other command types are not supported.
1243 * Note that these days the SCSI subsystem does not use
1244 * REQ_TYPE_SPECIAL requests anymore. These are only used
1245 * (directly or via blk_insert_request) by non-SCSI drivers.
1247 blk_dump_rq_flags(req, "SCSI bad req");
1255 req->errors = DID_NO_CONNECT << 16;
1259 * If we defer, the elv_next_request() returns NULL, but the
1260 * queue must be restarted, so we plug here if no returning
1261 * command will automatically do that.
1263 if (sdev->device_busy == 0)
1267 req->cmd_flags |= REQ_DONTPREP;
1274 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1277 * Called with the queue_lock held.
1279 static inline int scsi_dev_queue_ready(struct request_queue *q,
1280 struct scsi_device *sdev)
1282 if (sdev->device_busy >= sdev->queue_depth)
1284 if (sdev->device_busy == 0 && sdev->device_blocked) {
1286 * unblock after device_blocked iterates to zero
1288 if (--sdev->device_blocked == 0) {
1290 sdev_printk(KERN_INFO, sdev,
1291 "unblocking device at zero depth\n"));
1297 if (sdev->device_blocked)
1304 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1305 * return 0. We must end up running the queue again whenever 0 is
1306 * returned, else IO can hang.
1308 * Called with host_lock held.
1310 static inline int scsi_host_queue_ready(struct request_queue *q,
1311 struct Scsi_Host *shost,
1312 struct scsi_device *sdev)
1314 if (scsi_host_in_recovery(shost))
1316 if (shost->host_busy == 0 && shost->host_blocked) {
1318 * unblock after host_blocked iterates to zero
1320 if (--shost->host_blocked == 0) {
1322 printk("scsi%d unblocking host at zero depth\n",
1329 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1330 shost->host_blocked || shost->host_self_blocked) {
1331 if (list_empty(&sdev->starved_entry))
1332 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1336 /* We're OK to process the command, so we can't be starved */
1337 if (!list_empty(&sdev->starved_entry))
1338 list_del_init(&sdev->starved_entry);
1344 * Kill a request for a dead device
1346 static void scsi_kill_request(struct request *req, request_queue_t *q)
1348 struct scsi_cmnd *cmd = req->special;
1349 struct scsi_device *sdev = cmd->device;
1350 struct Scsi_Host *shost = sdev->host;
1352 blkdev_dequeue_request(req);
1354 if (unlikely(cmd == NULL)) {
1355 printk(KERN_CRIT "impossible request in %s.\n",
1360 scsi_init_cmd_errh(cmd);
1361 cmd->result = DID_NO_CONNECT << 16;
1362 atomic_inc(&cmd->device->iorequest_cnt);
1365 * SCSI request completion path will do scsi_device_unbusy(),
1366 * bump busy counts. To bump the counters, we need to dance
1367 * with the locks as normal issue path does.
1369 sdev->device_busy++;
1370 spin_unlock(sdev->request_queue->queue_lock);
1371 spin_lock(shost->host_lock);
1373 spin_unlock(shost->host_lock);
1374 spin_lock(sdev->request_queue->queue_lock);
1379 static void scsi_softirq_done(struct request *rq)
1381 struct scsi_cmnd *cmd = rq->completion_data;
1382 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
1385 INIT_LIST_HEAD(&cmd->eh_entry);
1387 disposition = scsi_decide_disposition(cmd);
1388 if (disposition != SUCCESS &&
1389 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1390 sdev_printk(KERN_ERR, cmd->device,
1391 "timing out command, waited %lus\n",
1393 disposition = SUCCESS;
1396 scsi_log_completion(cmd, disposition);
1398 switch (disposition) {
1400 scsi_finish_command(cmd);
1403 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1405 case ADD_TO_MLQUEUE:
1406 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1409 if (!scsi_eh_scmd_add(cmd, 0))
1410 scsi_finish_command(cmd);
1415 * Function: scsi_request_fn()
1417 * Purpose: Main strategy routine for SCSI.
1419 * Arguments: q - Pointer to actual queue.
1423 * Lock status: IO request lock assumed to be held when called.
1425 static void scsi_request_fn(struct request_queue *q)
1427 struct scsi_device *sdev = q->queuedata;
1428 struct Scsi_Host *shost;
1429 struct scsi_cmnd *cmd;
1430 struct request *req;
1433 printk("scsi: killing requests for dead queue\n");
1434 while ((req = elv_next_request(q)) != NULL)
1435 scsi_kill_request(req, q);
1439 if(!get_device(&sdev->sdev_gendev))
1440 /* We must be tearing the block queue down already */
1444 * To start with, we keep looping until the queue is empty, or until
1445 * the host is no longer able to accept any more requests.
1448 while (!blk_queue_plugged(q)) {
1451 * get next queueable request. We do this early to make sure
1452 * that the request is fully prepared even if we cannot
1455 req = elv_next_request(q);
1456 if (!req || !scsi_dev_queue_ready(q, sdev))
1459 if (unlikely(!scsi_device_online(sdev))) {
1460 sdev_printk(KERN_ERR, sdev,
1461 "rejecting I/O to offline device\n");
1462 scsi_kill_request(req, q);
1468 * Remove the request from the request list.
1470 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1471 blkdev_dequeue_request(req);
1472 sdev->device_busy++;
1474 spin_unlock(q->queue_lock);
1476 if (unlikely(cmd == NULL)) {
1477 printk(KERN_CRIT "impossible request in %s.\n"
1478 "please mail a stack trace to "
1479 "linux-scsi@vger.kernel.org\n",
1481 blk_dump_rq_flags(req, "foo");
1484 spin_lock(shost->host_lock);
1486 if (!scsi_host_queue_ready(q, shost, sdev))
1488 if (sdev->single_lun) {
1489 if (scsi_target(sdev)->starget_sdev_user &&
1490 scsi_target(sdev)->starget_sdev_user != sdev)
1492 scsi_target(sdev)->starget_sdev_user = sdev;
1497 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1498 * take the lock again.
1500 spin_unlock_irq(shost->host_lock);
1503 * Finally, initialize any error handling parameters, and set up
1504 * the timers for timeouts.
1506 scsi_init_cmd_errh(cmd);
1509 * Dispatch the command to the low-level driver.
1511 rtn = scsi_dispatch_cmd(cmd);
1512 spin_lock_irq(q->queue_lock);
1514 /* we're refusing the command; because of
1515 * the way locks get dropped, we need to
1516 * check here if plugging is required */
1517 if(sdev->device_busy == 0)
1527 spin_unlock_irq(shost->host_lock);
1530 * lock q, handle tag, requeue req, and decrement device_busy. We
1531 * must return with queue_lock held.
1533 * Decrementing device_busy without checking it is OK, as all such
1534 * cases (host limits or settings) should run the queue at some
1537 spin_lock_irq(q->queue_lock);
1538 blk_requeue_request(q, req);
1539 sdev->device_busy--;
1540 if(sdev->device_busy == 0)
1543 /* must be careful here...if we trigger the ->remove() function
1544 * we cannot be holding the q lock */
1545 spin_unlock_irq(q->queue_lock);
1546 put_device(&sdev->sdev_gendev);
1547 spin_lock_irq(q->queue_lock);
1550 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1552 struct device *host_dev;
1553 u64 bounce_limit = 0xffffffff;
1555 if (shost->unchecked_isa_dma)
1556 return BLK_BOUNCE_ISA;
1558 * Platforms with virtual-DMA translation
1559 * hardware have no practical limit.
1561 if (!PCI_DMA_BUS_IS_PHYS)
1562 return BLK_BOUNCE_ANY;
1564 host_dev = scsi_get_device(shost);
1565 if (host_dev && host_dev->dma_mask)
1566 bounce_limit = *host_dev->dma_mask;
1568 return bounce_limit;
1570 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1572 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1573 request_fn_proc *request_fn)
1575 struct request_queue *q;
1577 q = blk_init_queue(request_fn, NULL);
1581 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1582 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1583 blk_queue_max_sectors(q, shost->max_sectors);
1584 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1585 blk_queue_segment_boundary(q, shost->dma_boundary);
1587 if (!shost->use_clustering)
1588 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1591 EXPORT_SYMBOL(__scsi_alloc_queue);
1593 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1595 struct request_queue *q;
1597 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1601 blk_queue_prep_rq(q, scsi_prep_fn);
1602 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1603 blk_queue_softirq_done(q, scsi_softirq_done);
1607 void scsi_free_queue(struct request_queue *q)
1609 blk_cleanup_queue(q);
1613 * Function: scsi_block_requests()
1615 * Purpose: Utility function used by low-level drivers to prevent further
1616 * commands from being queued to the device.
1618 * Arguments: shost - Host in question
1622 * Lock status: No locks are assumed held.
1624 * Notes: There is no timer nor any other means by which the requests
1625 * get unblocked other than the low-level driver calling
1626 * scsi_unblock_requests().
1628 void scsi_block_requests(struct Scsi_Host *shost)
1630 shost->host_self_blocked = 1;
1632 EXPORT_SYMBOL(scsi_block_requests);
1635 * Function: scsi_unblock_requests()
1637 * Purpose: Utility function used by low-level drivers to allow further
1638 * commands from being queued to the device.
1640 * Arguments: shost - Host in question
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 * This is done as an API function so that changes to the
1651 * internals of the scsi mid-layer won't require wholesale
1652 * changes to drivers that use this feature.
1654 void scsi_unblock_requests(struct Scsi_Host *shost)
1656 shost->host_self_blocked = 0;
1657 scsi_run_host_queues(shost);
1659 EXPORT_SYMBOL(scsi_unblock_requests);
1661 int __init scsi_init_queue(void)
1665 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1666 sizeof(struct scsi_io_context),
1668 if (!scsi_io_context_cache) {
1669 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1673 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1674 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1675 int size = sgp->size * sizeof(struct scatterlist);
1677 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1678 SLAB_HWCACHE_ALIGN, NULL, NULL);
1680 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1684 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1687 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1695 void scsi_exit_queue(void)
1699 kmem_cache_destroy(scsi_io_context_cache);
1701 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1702 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1703 mempool_destroy(sgp->pool);
1704 kmem_cache_destroy(sgp->slab);
1709 * scsi_mode_select - issue a mode select
1710 * @sdev: SCSI device to be queried
1711 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1712 * @sp: Save page bit (0 == don't save, 1 == save)
1713 * @modepage: mode page being requested
1714 * @buffer: request buffer (may not be smaller than eight bytes)
1715 * @len: length of request buffer.
1716 * @timeout: command timeout
1717 * @retries: number of retries before failing
1718 * @data: returns a structure abstracting the mode header data
1719 * @sense: place to put sense data (or NULL if no sense to be collected).
1720 * must be SCSI_SENSE_BUFFERSIZE big.
1722 * Returns zero if successful; negative error number or scsi
1727 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1728 unsigned char *buffer, int len, int timeout, int retries,
1729 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1731 unsigned char cmd[10];
1732 unsigned char *real_buffer;
1735 memset(cmd, 0, sizeof(cmd));
1736 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1738 if (sdev->use_10_for_ms) {
1741 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1744 memcpy(real_buffer + 8, buffer, len);
1748 real_buffer[2] = data->medium_type;
1749 real_buffer[3] = data->device_specific;
1750 real_buffer[4] = data->longlba ? 0x01 : 0;
1752 real_buffer[6] = data->block_descriptor_length >> 8;
1753 real_buffer[7] = data->block_descriptor_length;
1755 cmd[0] = MODE_SELECT_10;
1759 if (len > 255 || data->block_descriptor_length > 255 ||
1763 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1766 memcpy(real_buffer + 4, buffer, len);
1769 real_buffer[1] = data->medium_type;
1770 real_buffer[2] = data->device_specific;
1771 real_buffer[3] = data->block_descriptor_length;
1774 cmd[0] = MODE_SELECT;
1778 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1779 sshdr, timeout, retries);
1783 EXPORT_SYMBOL_GPL(scsi_mode_select);
1786 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1787 * six bytes if necessary.
1788 * @sdev: SCSI device to be queried
1789 * @dbd: set if mode sense will allow block descriptors to be returned
1790 * @modepage: mode page being requested
1791 * @buffer: request buffer (may not be smaller than eight bytes)
1792 * @len: length of request buffer.
1793 * @timeout: command timeout
1794 * @retries: number of retries before failing
1795 * @data: returns a structure abstracting the mode header data
1796 * @sense: place to put sense data (or NULL if no sense to be collected).
1797 * must be SCSI_SENSE_BUFFERSIZE big.
1799 * Returns zero if unsuccessful, or the header offset (either 4
1800 * or 8 depending on whether a six or ten byte command was
1801 * issued) if successful.
1804 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1805 unsigned char *buffer, int len, int timeout, int retries,
1806 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1808 unsigned char cmd[12];
1812 struct scsi_sense_hdr my_sshdr;
1814 memset(data, 0, sizeof(*data));
1815 memset(&cmd[0], 0, 12);
1816 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1819 /* caller might not be interested in sense, but we need it */
1824 use_10_for_ms = sdev->use_10_for_ms;
1826 if (use_10_for_ms) {
1830 cmd[0] = MODE_SENSE_10;
1837 cmd[0] = MODE_SENSE;
1842 memset(buffer, 0, len);
1844 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1845 sshdr, timeout, retries);
1847 /* This code looks awful: what it's doing is making sure an
1848 * ILLEGAL REQUEST sense return identifies the actual command
1849 * byte as the problem. MODE_SENSE commands can return
1850 * ILLEGAL REQUEST if the code page isn't supported */
1852 if (use_10_for_ms && !scsi_status_is_good(result) &&
1853 (driver_byte(result) & DRIVER_SENSE)) {
1854 if (scsi_sense_valid(sshdr)) {
1855 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1856 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1858 * Invalid command operation code
1860 sdev->use_10_for_ms = 0;
1866 if(scsi_status_is_good(result)) {
1867 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1868 (modepage == 6 || modepage == 8))) {
1869 /* Initio breakage? */
1872 data->medium_type = 0;
1873 data->device_specific = 0;
1875 data->block_descriptor_length = 0;
1876 } else if(use_10_for_ms) {
1877 data->length = buffer[0]*256 + buffer[1] + 2;
1878 data->medium_type = buffer[2];
1879 data->device_specific = buffer[3];
1880 data->longlba = buffer[4] & 0x01;
1881 data->block_descriptor_length = buffer[6]*256
1884 data->length = buffer[0] + 1;
1885 data->medium_type = buffer[1];
1886 data->device_specific = buffer[2];
1887 data->block_descriptor_length = buffer[3];
1889 data->header_length = header_length;
1894 EXPORT_SYMBOL(scsi_mode_sense);
1897 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1900 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1902 struct scsi_sense_hdr sshdr;
1905 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
1908 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
1910 if ((scsi_sense_valid(&sshdr)) &&
1911 ((sshdr.sense_key == UNIT_ATTENTION) ||
1912 (sshdr.sense_key == NOT_READY))) {
1919 EXPORT_SYMBOL(scsi_test_unit_ready);
1922 * scsi_device_set_state - Take the given device through the device
1924 * @sdev: scsi device to change the state of.
1925 * @state: state to change to.
1927 * Returns zero if unsuccessful or an error if the requested
1928 * transition is illegal.
1931 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1933 enum scsi_device_state oldstate = sdev->sdev_state;
1935 if (state == oldstate)
1940 /* There are no legal states that come back to
1941 * created. This is the manually initialised start
2015 sdev->sdev_state = state;
2019 SCSI_LOG_ERROR_RECOVERY(1,
2020 sdev_printk(KERN_ERR, sdev,
2021 "Illegal state transition %s->%s\n",
2022 scsi_device_state_name(oldstate),
2023 scsi_device_state_name(state))
2027 EXPORT_SYMBOL(scsi_device_set_state);
2030 * scsi_device_quiesce - Block user issued commands.
2031 * @sdev: scsi device to quiesce.
2033 * This works by trying to transition to the SDEV_QUIESCE state
2034 * (which must be a legal transition). When the device is in this
2035 * state, only special requests will be accepted, all others will
2036 * be deferred. Since special requests may also be requeued requests,
2037 * a successful return doesn't guarantee the device will be
2038 * totally quiescent.
2040 * Must be called with user context, may sleep.
2042 * Returns zero if unsuccessful or an error if not.
2045 scsi_device_quiesce(struct scsi_device *sdev)
2047 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2051 scsi_run_queue(sdev->request_queue);
2052 while (sdev->device_busy) {
2053 msleep_interruptible(200);
2054 scsi_run_queue(sdev->request_queue);
2058 EXPORT_SYMBOL(scsi_device_quiesce);
2061 * scsi_device_resume - Restart user issued commands to a quiesced device.
2062 * @sdev: scsi device to resume.
2064 * Moves the device from quiesced back to running and restarts the
2067 * Must be called with user context, may sleep.
2070 scsi_device_resume(struct scsi_device *sdev)
2072 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2074 scsi_run_queue(sdev->request_queue);
2076 EXPORT_SYMBOL(scsi_device_resume);
2079 device_quiesce_fn(struct scsi_device *sdev, void *data)
2081 scsi_device_quiesce(sdev);
2085 scsi_target_quiesce(struct scsi_target *starget)
2087 starget_for_each_device(starget, NULL, device_quiesce_fn);
2089 EXPORT_SYMBOL(scsi_target_quiesce);
2092 device_resume_fn(struct scsi_device *sdev, void *data)
2094 scsi_device_resume(sdev);
2098 scsi_target_resume(struct scsi_target *starget)
2100 starget_for_each_device(starget, NULL, device_resume_fn);
2102 EXPORT_SYMBOL(scsi_target_resume);
2105 * scsi_internal_device_block - internal function to put a device
2106 * temporarily into the SDEV_BLOCK state
2107 * @sdev: device to block
2109 * Block request made by scsi lld's to temporarily stop all
2110 * scsi commands on the specified device. Called from interrupt
2111 * or normal process context.
2113 * Returns zero if successful or error if not
2116 * This routine transitions the device to the SDEV_BLOCK state
2117 * (which must be a legal transition). When the device is in this
2118 * state, all commands are deferred until the scsi lld reenables
2119 * the device with scsi_device_unblock or device_block_tmo fires.
2120 * This routine assumes the host_lock is held on entry.
2123 scsi_internal_device_block(struct scsi_device *sdev)
2125 request_queue_t *q = sdev->request_queue;
2126 unsigned long flags;
2129 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2134 * The device has transitioned to SDEV_BLOCK. Stop the
2135 * block layer from calling the midlayer with this device's
2138 spin_lock_irqsave(q->queue_lock, flags);
2140 spin_unlock_irqrestore(q->queue_lock, flags);
2144 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2147 * scsi_internal_device_unblock - resume a device after a block request
2148 * @sdev: device to resume
2150 * Called by scsi lld's or the midlayer to restart the device queue
2151 * for the previously suspended scsi device. Called from interrupt or
2152 * normal process context.
2154 * Returns zero if successful or error if not.
2157 * This routine transitions the device to the SDEV_RUNNING state
2158 * (which must be a legal transition) allowing the midlayer to
2159 * goose the queue for this device. This routine assumes the
2160 * host_lock is held upon entry.
2163 scsi_internal_device_unblock(struct scsi_device *sdev)
2165 request_queue_t *q = sdev->request_queue;
2167 unsigned long flags;
2170 * Try to transition the scsi device to SDEV_RUNNING
2171 * and goose the device queue if successful.
2173 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2177 spin_lock_irqsave(q->queue_lock, flags);
2179 spin_unlock_irqrestore(q->queue_lock, flags);
2183 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2186 device_block(struct scsi_device *sdev, void *data)
2188 scsi_internal_device_block(sdev);
2192 target_block(struct device *dev, void *data)
2194 if (scsi_is_target_device(dev))
2195 starget_for_each_device(to_scsi_target(dev), NULL,
2201 scsi_target_block(struct device *dev)
2203 if (scsi_is_target_device(dev))
2204 starget_for_each_device(to_scsi_target(dev), NULL,
2207 device_for_each_child(dev, NULL, target_block);
2209 EXPORT_SYMBOL_GPL(scsi_target_block);
2212 device_unblock(struct scsi_device *sdev, void *data)
2214 scsi_internal_device_unblock(sdev);
2218 target_unblock(struct device *dev, void *data)
2220 if (scsi_is_target_device(dev))
2221 starget_for_each_device(to_scsi_target(dev), NULL,
2227 scsi_target_unblock(struct device *dev)
2229 if (scsi_is_target_device(dev))
2230 starget_for_each_device(to_scsi_target(dev), NULL,
2233 device_for_each_child(dev, NULL, target_unblock);
2235 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2238 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2239 * @sg: scatter-gather list
2240 * @sg_count: number of segments in sg
2241 * @offset: offset in bytes into sg, on return offset into the mapped area
2242 * @len: bytes to map, on return number of bytes mapped
2244 * Returns virtual address of the start of the mapped page
2246 void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
2247 size_t *offset, size_t *len)
2250 size_t sg_len = 0, len_complete = 0;
2253 for (i = 0; i < sg_count; i++) {
2254 len_complete = sg_len; /* Complete sg-entries */
2255 sg_len += sg[i].length;
2256 if (sg_len > *offset)
2260 if (unlikely(i == sg_count)) {
2261 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2263 __FUNCTION__, sg_len, *offset, sg_count);
2268 /* Offset starting from the beginning of first page in this sg-entry */
2269 *offset = *offset - len_complete + sg[i].offset;
2271 /* Assumption: contiguous pages can be accessed as "page + i" */
2272 page = nth_page(sg[i].page, (*offset >> PAGE_SHIFT));
2273 *offset &= ~PAGE_MASK;
2275 /* Bytes in this sg-entry from *offset to the end of the page */
2276 sg_len = PAGE_SIZE - *offset;
2280 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2282 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2285 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously
2286 * mapped with scsi_kmap_atomic_sg
2287 * @virt: virtual address to be unmapped
2289 void scsi_kunmap_atomic_sg(void *virt)
2291 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2293 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);