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>
20 #include <scsi/scsi.h>
21 #include <scsi/scsi_dbg.h>
22 #include <scsi/scsi_device.h>
23 #include <scsi/scsi_driver.h>
24 #include <scsi/scsi_eh.h>
25 #include <scsi/scsi_host.h>
26 #include <scsi/scsi_request.h>
28 #include "scsi_priv.h"
29 #include "scsi_logging.h"
32 #define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
33 #define SG_MEMPOOL_SIZE 32
35 struct scsi_host_sg_pool {
42 #if (SCSI_MAX_PHYS_SEGMENTS < 32)
43 #error SCSI_MAX_PHYS_SEGMENTS is too small
46 #define SP(x) { x, "sgpool-" #x }
47 static struct scsi_host_sg_pool scsi_sg_pools[] = {
51 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
53 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
55 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
57 #if (SCSI_MAX_PHYS_SEGMENTS > 256)
58 #error SCSI_MAX_PHYS_SEGMENTS is too large
66 static void scsi_run_queue(struct request_queue *q);
69 * Function: scsi_unprep_request()
71 * Purpose: Remove all preparation done for a request, including its
72 * associated scsi_cmnd, so that it can be requeued.
74 * Arguments: req - request to unprepare
76 * Lock status: Assumed that no locks are held upon entry.
80 static void scsi_unprep_request(struct request *req)
82 struct scsi_cmnd *cmd = req->special;
84 req->flags &= ~REQ_DONTPREP;
85 req->special = (req->flags & REQ_SPECIAL) ? cmd->sc_request : NULL;
87 scsi_put_command(cmd);
91 * Function: scsi_queue_insert()
93 * Purpose: Insert a command in the midlevel queue.
95 * Arguments: cmd - command that we are adding to queue.
96 * reason - why we are inserting command to queue.
98 * Lock status: Assumed that lock is not held upon entry.
102 * Notes: We do this for one of two cases. Either the host is busy
103 * and it cannot accept any more commands for the time being,
104 * or the device returned QUEUE_FULL and can accept no more
106 * Notes: This could be called either from an interrupt context or a
107 * normal process context.
109 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
111 struct Scsi_Host *host = cmd->device->host;
112 struct scsi_device *device = cmd->device;
113 struct request_queue *q = device->request_queue;
117 printk("Inserting command %p into mlqueue\n", cmd));
120 * Set the appropriate busy bit for the device/host.
122 * If the host/device isn't busy, assume that something actually
123 * completed, and that we should be able to queue a command now.
125 * Note that the prior mid-layer assumption that any host could
126 * always queue at least one command is now broken. The mid-layer
127 * will implement a user specifiable stall (see
128 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
129 * if a command is requeued with no other commands outstanding
130 * either for the device or for the host.
132 if (reason == SCSI_MLQUEUE_HOST_BUSY)
133 host->host_blocked = host->max_host_blocked;
134 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
135 device->device_blocked = device->max_device_blocked;
138 * Decrement the counters, since these commands are no longer
139 * active on the host/device.
141 scsi_device_unbusy(device);
144 * Requeue this command. It will go before all other commands
145 * that are already in the queue.
147 * NOTE: there is magic here about the way the queue is plugged if
148 * we have no outstanding commands.
150 * Although we *don't* plug the queue, we call the request
151 * function. The SCSI request function detects the blocked condition
152 * and plugs the queue appropriately.
154 spin_lock_irqsave(q->queue_lock, flags);
155 blk_requeue_request(q, cmd->request);
156 spin_unlock_irqrestore(q->queue_lock, flags);
164 * Function: scsi_do_req
166 * Purpose: Queue a SCSI request
168 * Arguments: sreq - command descriptor.
169 * cmnd - actual SCSI command to be performed.
170 * buffer - data buffer.
171 * bufflen - size of data buffer.
172 * done - completion function to be run.
173 * timeout - how long to let it run before timeout.
174 * retries - number of retries we allow.
176 * Lock status: No locks held upon entry.
180 * Notes: This function is only used for queueing requests for things
181 * like ioctls and character device requests - this is because
182 * we essentially just inject a request into the queue for the
185 * In order to support the scsi_device_quiesce function, we
186 * now inject requests on the *head* of the device queue
187 * rather than the tail.
189 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
190 void *buffer, unsigned bufflen,
191 void (*done)(struct scsi_cmnd *),
192 int timeout, int retries)
195 * If the upper level driver is reusing these things, then
196 * we should release the low-level block now. Another one will
197 * be allocated later when this request is getting queued.
199 __scsi_release_request(sreq);
202 * Our own function scsi_done (which marks the host as not busy,
203 * disables the timeout counter, etc) will be called by us or by the
204 * scsi_hosts[host].queuecommand() function needs to also call
205 * the completion function for the high level driver.
207 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
208 sreq->sr_bufflen = bufflen;
209 sreq->sr_buffer = buffer;
210 sreq->sr_allowed = retries;
211 sreq->sr_done = done;
212 sreq->sr_timeout_per_command = timeout;
214 if (sreq->sr_cmd_len == 0)
215 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
218 * head injection *required* here otherwise quiesce won't work
220 * Because users of this function are apt to reuse requests with no
221 * modification, we have to sanitise the request flags here
223 sreq->sr_request->flags &= ~REQ_DONTPREP;
224 blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
227 EXPORT_SYMBOL(scsi_do_req);
230 * scsi_execute - insert request and wait for the result
233 * @data_direction: data direction
234 * @buffer: data buffer
235 * @bufflen: len of buffer
236 * @sense: optional sense buffer
237 * @timeout: request timeout in seconds
238 * @retries: number of times to retry request
239 * @flags: or into request flags;
241 * returns the req->errors value which is the the scsi_cmnd result
244 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
245 int data_direction, void *buffer, unsigned bufflen,
246 unsigned char *sense, int timeout, int retries, int flags)
249 int write = (data_direction == DMA_TO_DEVICE);
250 int ret = DRIVER_ERROR << 24;
252 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
254 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
255 buffer, bufflen, __GFP_WAIT))
258 req->cmd_len = COMMAND_SIZE(cmd[0]);
259 memcpy(req->cmd, cmd, req->cmd_len);
262 req->retries = retries;
263 req->timeout = timeout;
264 req->flags |= flags | REQ_BLOCK_PC | REQ_SPECIAL | REQ_QUIET;
267 * head injection *required* here otherwise quiesce won't work
269 blk_execute_rq(req->q, NULL, req, 1);
273 blk_put_request(req);
277 EXPORT_SYMBOL(scsi_execute);
280 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
281 int data_direction, void *buffer, unsigned bufflen,
282 struct scsi_sense_hdr *sshdr, int timeout, int retries)
288 sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
290 return DRIVER_ERROR << 24;
291 memset(sense, 0, SCSI_SENSE_BUFFERSIZE);
293 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
294 sense, timeout, retries, 0);
296 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
301 EXPORT_SYMBOL(scsi_execute_req);
303 struct scsi_io_context {
305 void (*done)(void *data, char *sense, int result, int resid);
306 char sense[SCSI_SENSE_BUFFERSIZE];
309 static void scsi_end_async(struct request *req)
311 struct scsi_io_context *sioc = req->end_io_data;
314 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
317 __blk_put_request(req->q, req);
320 static int scsi_merge_bio(struct request *rq, struct bio *bio)
322 struct request_queue *q = rq->q;
324 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
325 if (rq_data_dir(rq) == WRITE)
326 bio->bi_rw |= (1 << BIO_RW);
327 blk_queue_bounce(q, &bio);
330 blk_rq_bio_prep(q, rq, bio);
331 else if (!q->back_merge_fn(q, rq, bio))
334 rq->biotail->bi_next = bio;
336 rq->hard_nr_sectors += bio_sectors(bio);
337 rq->nr_sectors = rq->hard_nr_sectors;
343 static int scsi_bi_endio(struct bio *bio, unsigned int bytes_done, int error)
353 * scsi_req_map_sg - map a scatterlist into a request
354 * @rq: request to fill
356 * @nsegs: number of elements
357 * @bufflen: len of buffer
358 * @gfp: memory allocation flags
360 * scsi_req_map_sg maps a scatterlist into a request so that the
361 * request can be sent to the block layer. We do not trust the scatterlist
362 * sent to use, as some ULDs use that struct to only organize the pages.
364 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
365 int nsegs, unsigned bufflen, gfp_t gfp)
367 struct request_queue *q = rq->q;
368 int nr_pages = (bufflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
369 unsigned int data_len = 0, len, bytes, off;
371 struct bio *bio = NULL;
372 int i, err, nr_vecs = 0;
374 for (i = 0; i < nsegs; i++) {
381 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
384 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
387 bio = bio_alloc(gfp, nr_vecs);
392 bio->bi_end_io = scsi_bi_endio;
395 if (bio_add_pc_page(q, bio, page, bytes, off) !=
402 if (bio->bi_vcnt >= nr_vecs) {
403 err = scsi_merge_bio(rq, bio);
405 bio_endio(bio, bio->bi_size, 0);
417 rq->buffer = rq->data = NULL;
418 rq->data_len = data_len;
422 while ((bio = rq->bio) != NULL) {
423 rq->bio = bio->bi_next;
425 * call endio instead of bio_put incase it was bounced
427 bio_endio(bio, bio->bi_size, 0);
434 * scsi_execute_async - insert request
437 * @data_direction: data direction
438 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
439 * @bufflen: len of buffer
440 * @use_sg: if buffer is a scatterlist this is the number of elements
441 * @timeout: request timeout in seconds
442 * @retries: number of times to retry request
443 * @flags: or into request flags
445 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
446 int data_direction, void *buffer, unsigned bufflen,
447 int use_sg, int timeout, int retries, void *privdata,
448 void (*done)(void *, char *, int, int), gfp_t gfp)
451 struct scsi_io_context *sioc;
453 int write = (data_direction == DMA_TO_DEVICE);
455 sioc = kzalloc(sizeof(*sioc), gfp);
457 return DRIVER_ERROR << 24;
459 req = blk_get_request(sdev->request_queue, write, gfp);
464 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
466 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
471 req->cmd_len = COMMAND_SIZE(cmd[0]);
472 memcpy(req->cmd, cmd, req->cmd_len);
473 req->sense = sioc->sense;
475 req->timeout = timeout;
476 req->retries = retries;
477 req->flags |= REQ_BLOCK_PC | REQ_QUIET;
478 req->end_io_data = sioc;
480 sioc->data = privdata;
483 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
487 blk_put_request(req);
490 return DRIVER_ERROR << 24;
492 EXPORT_SYMBOL_GPL(scsi_execute_async);
495 * Function: scsi_init_cmd_errh()
497 * Purpose: Initialize cmd fields related to error handling.
499 * Arguments: cmd - command that is ready to be queued.
503 * Notes: This function has the job of initializing a number of
504 * fields related to error handling. Typically this will
505 * be called once for each command, as required.
507 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
509 cmd->serial_number = 0;
511 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
513 if (cmd->cmd_len == 0)
514 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
517 * We need saved copies of a number of fields - this is because
518 * error handling may need to overwrite these with different values
519 * to run different commands, and once error handling is complete,
520 * we will need to restore these values prior to running the actual
523 cmd->old_use_sg = cmd->use_sg;
524 cmd->old_cmd_len = cmd->cmd_len;
525 cmd->sc_old_data_direction = cmd->sc_data_direction;
526 cmd->old_underflow = cmd->underflow;
527 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
528 cmd->buffer = cmd->request_buffer;
529 cmd->bufflen = cmd->request_bufflen;
535 * Function: scsi_setup_cmd_retry()
537 * Purpose: Restore the command state for a retry
539 * Arguments: cmd - command to be restored
543 * Notes: Immediately prior to retrying a command, we need
544 * to restore certain fields that we saved above.
546 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
548 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
549 cmd->request_buffer = cmd->buffer;
550 cmd->request_bufflen = cmd->bufflen;
551 cmd->use_sg = cmd->old_use_sg;
552 cmd->cmd_len = cmd->old_cmd_len;
553 cmd->sc_data_direction = cmd->sc_old_data_direction;
554 cmd->underflow = cmd->old_underflow;
557 void scsi_device_unbusy(struct scsi_device *sdev)
559 struct Scsi_Host *shost = sdev->host;
562 spin_lock_irqsave(shost->host_lock, flags);
564 if (unlikely(scsi_host_in_recovery(shost) &&
566 scsi_eh_wakeup(shost);
567 spin_unlock(shost->host_lock);
568 spin_lock(sdev->request_queue->queue_lock);
570 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
574 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
575 * and call blk_run_queue for all the scsi_devices on the target -
576 * including current_sdev first.
578 * Called with *no* scsi locks held.
580 static void scsi_single_lun_run(struct scsi_device *current_sdev)
582 struct Scsi_Host *shost = current_sdev->host;
583 struct scsi_device *sdev, *tmp;
584 struct scsi_target *starget = scsi_target(current_sdev);
587 spin_lock_irqsave(shost->host_lock, flags);
588 starget->starget_sdev_user = NULL;
589 spin_unlock_irqrestore(shost->host_lock, flags);
592 * Call blk_run_queue for all LUNs on the target, starting with
593 * current_sdev. We race with others (to set starget_sdev_user),
594 * but in most cases, we will be first. Ideally, each LU on the
595 * target would get some limited time or requests on the target.
597 blk_run_queue(current_sdev->request_queue);
599 spin_lock_irqsave(shost->host_lock, flags);
600 if (starget->starget_sdev_user)
602 list_for_each_entry_safe(sdev, tmp, &starget->devices,
603 same_target_siblings) {
604 if (sdev == current_sdev)
606 if (scsi_device_get(sdev))
609 spin_unlock_irqrestore(shost->host_lock, flags);
610 blk_run_queue(sdev->request_queue);
611 spin_lock_irqsave(shost->host_lock, flags);
613 scsi_device_put(sdev);
616 spin_unlock_irqrestore(shost->host_lock, flags);
620 * Function: scsi_run_queue()
622 * Purpose: Select a proper request queue to serve next
624 * Arguments: q - last request's queue
628 * Notes: The previous command was completely finished, start
629 * a new one if possible.
631 static void scsi_run_queue(struct request_queue *q)
633 struct scsi_device *sdev = q->queuedata;
634 struct Scsi_Host *shost = sdev->host;
637 if (sdev->single_lun)
638 scsi_single_lun_run(sdev);
640 spin_lock_irqsave(shost->host_lock, flags);
641 while (!list_empty(&shost->starved_list) &&
642 !shost->host_blocked && !shost->host_self_blocked &&
643 !((shost->can_queue > 0) &&
644 (shost->host_busy >= shost->can_queue))) {
646 * As long as shost is accepting commands and we have
647 * starved queues, call blk_run_queue. scsi_request_fn
648 * drops the queue_lock and can add us back to the
651 * host_lock protects the starved_list and starved_entry.
652 * scsi_request_fn must get the host_lock before checking
653 * or modifying starved_list or starved_entry.
655 sdev = list_entry(shost->starved_list.next,
656 struct scsi_device, starved_entry);
657 list_del_init(&sdev->starved_entry);
658 spin_unlock_irqrestore(shost->host_lock, flags);
660 blk_run_queue(sdev->request_queue);
662 spin_lock_irqsave(shost->host_lock, flags);
663 if (unlikely(!list_empty(&sdev->starved_entry)))
665 * sdev lost a race, and was put back on the
666 * starved list. This is unlikely but without this
667 * in theory we could loop forever.
671 spin_unlock_irqrestore(shost->host_lock, flags);
677 * Function: scsi_requeue_command()
679 * Purpose: Handle post-processing of completed commands.
681 * Arguments: q - queue to operate on
682 * cmd - command that may need to be requeued.
686 * Notes: After command completion, there may be blocks left
687 * over which weren't finished by the previous command
688 * this can be for a number of reasons - the main one is
689 * I/O errors in the middle of the request, in which case
690 * we need to request the blocks that come after the bad
692 * Notes: Upon return, cmd is a stale pointer.
694 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
696 struct request *req = cmd->request;
699 scsi_unprep_request(req);
700 spin_lock_irqsave(q->queue_lock, flags);
701 blk_requeue_request(q, req);
702 spin_unlock_irqrestore(q->queue_lock, flags);
707 void scsi_next_command(struct scsi_cmnd *cmd)
709 struct scsi_device *sdev = cmd->device;
710 struct request_queue *q = sdev->request_queue;
712 /* need to hold a reference on the device before we let go of the cmd */
713 get_device(&sdev->sdev_gendev);
715 scsi_put_command(cmd);
718 /* ok to remove device now */
719 put_device(&sdev->sdev_gendev);
722 void scsi_run_host_queues(struct Scsi_Host *shost)
724 struct scsi_device *sdev;
726 shost_for_each_device(sdev, shost)
727 scsi_run_queue(sdev->request_queue);
731 * Function: scsi_end_request()
733 * Purpose: Post-processing of completed commands (usually invoked at end
734 * of upper level post-processing and scsi_io_completion).
736 * Arguments: cmd - command that is complete.
737 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
738 * bytes - number of bytes of completed I/O
739 * requeue - indicates whether we should requeue leftovers.
741 * Lock status: Assumed that lock is not held upon entry.
743 * Returns: cmd if requeue required, NULL otherwise.
745 * Notes: This is called for block device requests in order to
746 * mark some number of sectors as complete.
748 * We are guaranteeing that the request queue will be goosed
749 * at some point during this call.
750 * Notes: If cmd was requeued, upon return it will be a stale pointer.
752 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
753 int bytes, int requeue)
755 request_queue_t *q = cmd->device->request_queue;
756 struct request *req = cmd->request;
760 * If there are blocks left over at the end, set up the command
761 * to queue the remainder of them.
763 if (end_that_request_chunk(req, uptodate, bytes)) {
764 int leftover = (req->hard_nr_sectors << 9);
766 if (blk_pc_request(req))
767 leftover = req->data_len;
769 /* kill remainder if no retrys */
770 if (!uptodate && blk_noretry_request(req))
771 end_that_request_chunk(req, 0, leftover);
775 * Bleah. Leftovers again. Stick the
776 * leftovers in the front of the
777 * queue, and goose the queue again.
779 scsi_requeue_command(q, cmd);
786 add_disk_randomness(req->rq_disk);
788 spin_lock_irqsave(q->queue_lock, flags);
789 if (blk_rq_tagged(req))
790 blk_queue_end_tag(q, req);
791 end_that_request_last(req);
792 spin_unlock_irqrestore(q->queue_lock, flags);
795 * This will goose the queue request function at the end, so we don't
796 * need to worry about launching another command.
798 scsi_next_command(cmd);
802 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
804 struct scsi_host_sg_pool *sgp;
805 struct scatterlist *sgl;
807 BUG_ON(!cmd->use_sg);
809 switch (cmd->use_sg) {
819 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
823 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
827 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
838 sgp = scsi_sg_pools + cmd->sglist_len;
839 sgl = mempool_alloc(sgp->pool, gfp_mask);
843 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
845 struct scsi_host_sg_pool *sgp;
847 BUG_ON(index >= SG_MEMPOOL_NR);
849 sgp = scsi_sg_pools + index;
850 mempool_free(sgl, sgp->pool);
854 * Function: scsi_release_buffers()
856 * Purpose: Completion processing for block device I/O requests.
858 * Arguments: cmd - command that we are bailing.
860 * Lock status: Assumed that no lock is held upon entry.
864 * Notes: In the event that an upper level driver rejects a
865 * command, we must release resources allocated during
866 * the __init_io() function. Primarily this would involve
867 * the scatter-gather table, and potentially any bounce
870 static void scsi_release_buffers(struct scsi_cmnd *cmd)
872 struct request *req = cmd->request;
875 * Free up any indirection buffers we allocated for DMA purposes.
878 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
879 else if (cmd->request_buffer != req->buffer)
880 kfree(cmd->request_buffer);
883 * Zero these out. They now point to freed memory, and it is
884 * dangerous to hang onto the pointers.
888 cmd->request_buffer = NULL;
889 cmd->request_bufflen = 0;
893 * Function: scsi_io_completion()
895 * Purpose: Completion processing for block device I/O requests.
897 * Arguments: cmd - command that is finished.
899 * Lock status: Assumed that no lock is held upon entry.
903 * Notes: This function is matched in terms of capabilities to
904 * the function that created the scatter-gather list.
905 * In other words, if there are no bounce buffers
906 * (the normal case for most drivers), we don't need
907 * the logic to deal with cleaning up afterwards.
909 * We must do one of several things here:
911 * a) Call scsi_end_request. This will finish off the
912 * specified number of sectors. If we are done, the
913 * command block will be released, and the queue
914 * function will be goosed. If we are not done, then
915 * scsi_end_request will directly goose the queue.
917 * b) We can just use scsi_requeue_command() here. This would
918 * be used if we just wanted to retry, for example.
920 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
921 unsigned int block_bytes)
923 int result = cmd->result;
924 int this_count = cmd->bufflen;
925 request_queue_t *q = cmd->device->request_queue;
926 struct request *req = cmd->request;
927 int clear_errors = 1;
928 struct scsi_sense_hdr sshdr;
930 int sense_deferred = 0;
932 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
936 * Free up any indirection buffers we allocated for DMA purposes.
937 * For the case of a READ, we need to copy the data out of the
938 * bounce buffer and into the real buffer.
941 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
942 else if (cmd->buffer != req->buffer) {
943 if (rq_data_dir(req) == READ) {
945 char *to = bio_kmap_irq(req->bio, &flags);
946 memcpy(to, cmd->buffer, cmd->bufflen);
947 bio_kunmap_irq(to, &flags);
953 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
955 sense_deferred = scsi_sense_is_deferred(&sshdr);
957 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
958 req->errors = result;
961 if (sense_valid && req->sense) {
963 * SG_IO wants current and deferred errors
965 int len = 8 + cmd->sense_buffer[7];
967 if (len > SCSI_SENSE_BUFFERSIZE)
968 len = SCSI_SENSE_BUFFERSIZE;
969 memcpy(req->sense, cmd->sense_buffer, len);
970 req->sense_len = len;
973 req->data_len = cmd->resid;
977 * Zero these out. They now point to freed memory, and it is
978 * dangerous to hang onto the pointers.
982 cmd->request_buffer = NULL;
983 cmd->request_bufflen = 0;
986 * Next deal with any sectors which we were able to correctly
989 if (good_bytes >= 0) {
990 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
991 req->nr_sectors, good_bytes));
992 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
997 * If multiple sectors are requested in one buffer, then
998 * they will have been finished off by the first command.
999 * If not, then we have a multi-buffer command.
1001 * If block_bytes != 0, it means we had a medium error
1002 * of some sort, and that we want to mark some number of
1003 * sectors as not uptodate. Thus we want to inhibit
1004 * requeueing right here - we will requeue down below
1005 * when we handle the bad sectors.
1009 * If the command completed without error, then either
1010 * finish off the rest of the command, or start a new one.
1012 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
1016 * Now, if we were good little boys and girls, Santa left us a request
1017 * sense buffer. We can extract information from this, so we
1018 * can choose a block to remap, etc.
1020 if (sense_valid && !sense_deferred) {
1021 switch (sshdr.sense_key) {
1022 case UNIT_ATTENTION:
1023 if (cmd->device->removable) {
1024 /* detected disc change. set a bit
1025 * and quietly refuse further access.
1027 cmd->device->changed = 1;
1028 scsi_end_request(cmd, 0,
1033 * Must have been a power glitch, or a
1034 * bus reset. Could not have been a
1035 * media change, so we just retry the
1036 * request and see what happens.
1038 scsi_requeue_command(q, cmd);
1042 case ILLEGAL_REQUEST:
1044 * If we had an ILLEGAL REQUEST returned, then we may
1045 * have performed an unsupported command. The only
1046 * thing this should be would be a ten byte read where
1047 * only a six byte read was supported. Also, on a
1048 * system where READ CAPACITY failed, we may have read
1049 * past the end of the disk.
1051 if ((cmd->device->use_10_for_rw &&
1052 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
1053 (cmd->cmnd[0] == READ_10 ||
1054 cmd->cmnd[0] == WRITE_10)) {
1055 cmd->device->use_10_for_rw = 0;
1057 * This will cause a retry with a 6-byte
1060 scsi_requeue_command(q, cmd);
1063 scsi_end_request(cmd, 0, this_count, 1);
1069 * If the device is in the process of becoming ready,
1072 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
1073 scsi_requeue_command(q, cmd);
1076 if (!(req->flags & REQ_QUIET))
1077 scmd_printk(KERN_INFO, cmd,
1078 "Device not ready.\n");
1079 scsi_end_request(cmd, 0, this_count, 1);
1081 case VOLUME_OVERFLOW:
1082 if (!(req->flags & REQ_QUIET)) {
1083 scmd_printk(KERN_INFO, cmd,
1084 "Volume overflow, CDB: ");
1085 __scsi_print_command(cmd->data_cmnd);
1086 scsi_print_sense("", cmd);
1088 scsi_end_request(cmd, 0, block_bytes, 1);
1093 } /* driver byte != 0 */
1094 if (host_byte(result) == DID_RESET) {
1096 * Third party bus reset or reset for error
1097 * recovery reasons. Just retry the request
1098 * and see what happens.
1100 scsi_requeue_command(q, cmd);
1104 if (!(req->flags & REQ_QUIET)) {
1105 scmd_printk(KERN_INFO, cmd,
1106 "SCSI error: return code = 0x%x\n", result);
1108 if (driver_byte(result) & DRIVER_SENSE)
1109 scsi_print_sense("", cmd);
1112 * Mark a single buffer as not uptodate. Queue the remainder.
1113 * We sometimes get this cruft in the event that a medium error
1114 * isn't properly reported.
1116 block_bytes = req->hard_cur_sectors << 9;
1118 block_bytes = req->data_len;
1119 scsi_end_request(cmd, 0, block_bytes, 1);
1122 EXPORT_SYMBOL(scsi_io_completion);
1125 * Function: scsi_init_io()
1127 * Purpose: SCSI I/O initialize function.
1129 * Arguments: cmd - Command descriptor we wish to initialize
1131 * Returns: 0 on success
1132 * BLKPREP_DEFER if the failure is retryable
1133 * BLKPREP_KILL if the failure is fatal
1135 static int scsi_init_io(struct scsi_cmnd *cmd)
1137 struct request *req = cmd->request;
1138 struct scatterlist *sgpnt;
1142 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
1144 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
1145 cmd->request_bufflen = req->data_len;
1146 cmd->request_buffer = req->data;
1147 req->buffer = req->data;
1153 * we used to not use scatter-gather for single segment request,
1154 * but now we do (it makes highmem I/O easier to support without
1157 cmd->use_sg = req->nr_phys_segments;
1160 * if sg table allocation fails, requeue request later.
1162 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
1163 if (unlikely(!sgpnt)) {
1164 scsi_unprep_request(req);
1165 return BLKPREP_DEFER;
1168 cmd->request_buffer = (char *) sgpnt;
1169 cmd->request_bufflen = req->nr_sectors << 9;
1170 if (blk_pc_request(req))
1171 cmd->request_bufflen = req->data_len;
1175 * Next, walk the list, and fill in the addresses and sizes of
1178 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
1181 * mapped well, send it off
1183 if (likely(count <= cmd->use_sg)) {
1184 cmd->use_sg = count;
1188 printk(KERN_ERR "Incorrect number of segments after building list\n");
1189 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
1190 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
1191 req->current_nr_sectors);
1193 /* release the command and kill it */
1194 scsi_release_buffers(cmd);
1195 scsi_put_command(cmd);
1196 return BLKPREP_KILL;
1199 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
1201 struct scsi_device *sdev = q->queuedata;
1202 struct scsi_driver *drv;
1204 if (sdev->sdev_state == SDEV_RUNNING) {
1205 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1207 if (drv->prepare_flush)
1208 return drv->prepare_flush(q, rq);
1214 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
1216 struct scsi_device *sdev = q->queuedata;
1217 struct request *flush_rq = rq->end_io_data;
1218 struct scsi_driver *drv;
1220 if (flush_rq->errors) {
1221 printk("scsi: barrier error, disabling flush support\n");
1222 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1225 if (sdev->sdev_state == SDEV_RUNNING) {
1226 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1227 drv->end_flush(q, rq);
1231 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1232 sector_t *error_sector)
1234 struct scsi_device *sdev = q->queuedata;
1235 struct scsi_driver *drv;
1237 if (sdev->sdev_state != SDEV_RUNNING)
1240 drv = *(struct scsi_driver **) disk->private_data;
1241 if (drv->issue_flush)
1242 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1247 static void scsi_generic_done(struct scsi_cmnd *cmd)
1249 BUG_ON(!blk_pc_request(cmd->request));
1250 scsi_io_completion(cmd, cmd->result == 0 ? cmd->bufflen : 0, 0);
1253 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1255 struct scsi_device *sdev = q->queuedata;
1256 struct scsi_cmnd *cmd;
1257 int specials_only = 0;
1260 * Just check to see if the device is online. If it isn't, we
1261 * refuse to process any commands. The device must be brought
1262 * online before trying any recovery commands
1264 if (unlikely(!scsi_device_online(sdev))) {
1265 sdev_printk(KERN_ERR, sdev,
1266 "rejecting I/O to offline device\n");
1269 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1270 /* OK, we're not in a running state don't prep
1272 if (sdev->sdev_state == SDEV_DEL) {
1273 /* Device is fully deleted, no commands
1274 * at all allowed down */
1275 sdev_printk(KERN_ERR, sdev,
1276 "rejecting I/O to dead device\n");
1279 /* OK, we only allow special commands (i.e. not
1280 * user initiated ones */
1281 specials_only = sdev->sdev_state;
1285 * Find the actual device driver associated with this command.
1286 * The SPECIAL requests are things like character device or
1287 * ioctls, which did not originate from ll_rw_blk. Note that
1288 * the special field is also used to indicate the cmd for
1289 * the remainder of a partially fulfilled request that can
1290 * come up when there is a medium error. We have to treat
1291 * these two cases differently. We differentiate by looking
1292 * at request->cmd, as this tells us the real story.
1294 if (req->flags & REQ_SPECIAL && req->special) {
1295 struct scsi_request *sreq = req->special;
1297 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1298 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1301 scsi_init_cmd_from_req(cmd, sreq);
1304 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1306 if(unlikely(specials_only) && !(req->flags & REQ_SPECIAL)) {
1307 if(specials_only == SDEV_QUIESCE ||
1308 specials_only == SDEV_BLOCK)
1311 sdev_printk(KERN_ERR, sdev,
1312 "rejecting I/O to device being removed\n");
1318 * Now try and find a command block that we can use.
1320 if (!req->special) {
1321 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1327 /* pull a tag out of the request if we have one */
1328 cmd->tag = req->tag;
1330 blk_dump_rq_flags(req, "SCSI bad req");
1334 /* note the overloading of req->special. When the tag
1335 * is active it always means cmd. If the tag goes
1336 * back for re-queueing, it may be reset */
1341 * FIXME: drop the lock here because the functions below
1342 * expect to be called without the queue lock held. Also,
1343 * previously, we dequeued the request before dropping the
1344 * lock. We hope REQ_STARTED prevents anything untoward from
1347 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1348 struct scsi_driver *drv;
1352 * This will do a couple of things:
1353 * 1) Fill in the actual SCSI command.
1354 * 2) Fill in any other upper-level specific fields
1357 * If this returns 0, it means that the request failed
1358 * (reading past end of disk, reading offline device,
1359 * etc). This won't actually talk to the device, but
1360 * some kinds of consistency checking may cause the
1361 * request to be rejected immediately.
1365 * This sets up the scatter-gather table (allocating if
1368 ret = scsi_init_io(cmd);
1370 /* For BLKPREP_KILL/DEFER the cmd was released */
1378 * Initialize the actual SCSI command for this request.
1381 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1382 if (unlikely(!drv->init_command(cmd))) {
1383 scsi_release_buffers(cmd);
1384 scsi_put_command(cmd);
1388 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1389 cmd->cmd_len = req->cmd_len;
1390 if (rq_data_dir(req) == WRITE)
1391 cmd->sc_data_direction = DMA_TO_DEVICE;
1392 else if (req->data_len)
1393 cmd->sc_data_direction = DMA_FROM_DEVICE;
1395 cmd->sc_data_direction = DMA_NONE;
1397 cmd->transfersize = req->data_len;
1398 cmd->allowed = req->retries;
1399 cmd->timeout_per_command = req->timeout;
1400 cmd->done = scsi_generic_done;
1405 * The request is now prepped, no need to come back here
1407 req->flags |= REQ_DONTPREP;
1411 /* If we defer, the elv_next_request() returns NULL, but the
1412 * queue must be restarted, so we plug here if no returning
1413 * command will automatically do that. */
1414 if (sdev->device_busy == 0)
1416 return BLKPREP_DEFER;
1418 req->errors = DID_NO_CONNECT << 16;
1419 return BLKPREP_KILL;
1423 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1426 * Called with the queue_lock held.
1428 static inline int scsi_dev_queue_ready(struct request_queue *q,
1429 struct scsi_device *sdev)
1431 if (sdev->device_busy >= sdev->queue_depth)
1433 if (sdev->device_busy == 0 && sdev->device_blocked) {
1435 * unblock after device_blocked iterates to zero
1437 if (--sdev->device_blocked == 0) {
1439 sdev_printk(KERN_INFO, sdev,
1440 "unblocking device at zero depth\n"));
1446 if (sdev->device_blocked)
1453 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1454 * return 0. We must end up running the queue again whenever 0 is
1455 * returned, else IO can hang.
1457 * Called with host_lock held.
1459 static inline int scsi_host_queue_ready(struct request_queue *q,
1460 struct Scsi_Host *shost,
1461 struct scsi_device *sdev)
1463 if (scsi_host_in_recovery(shost))
1465 if (shost->host_busy == 0 && shost->host_blocked) {
1467 * unblock after host_blocked iterates to zero
1469 if (--shost->host_blocked == 0) {
1471 printk("scsi%d unblocking host at zero depth\n",
1478 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1479 shost->host_blocked || shost->host_self_blocked) {
1480 if (list_empty(&sdev->starved_entry))
1481 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1485 /* We're OK to process the command, so we can't be starved */
1486 if (!list_empty(&sdev->starved_entry))
1487 list_del_init(&sdev->starved_entry);
1493 * Kill a request for a dead device
1495 static void scsi_kill_request(struct request *req, request_queue_t *q)
1497 struct scsi_cmnd *cmd = req->special;
1499 blkdev_dequeue_request(req);
1501 if (unlikely(cmd == NULL)) {
1502 printk(KERN_CRIT "impossible request in %s.\n",
1507 scsi_init_cmd_errh(cmd);
1508 cmd->result = DID_NO_CONNECT << 16;
1509 atomic_inc(&cmd->device->iorequest_cnt);
1514 * Function: scsi_request_fn()
1516 * Purpose: Main strategy routine for SCSI.
1518 * Arguments: q - Pointer to actual queue.
1522 * Lock status: IO request lock assumed to be held when called.
1524 static void scsi_request_fn(struct request_queue *q)
1526 struct scsi_device *sdev = q->queuedata;
1527 struct Scsi_Host *shost;
1528 struct scsi_cmnd *cmd;
1529 struct request *req;
1532 printk("scsi: killing requests for dead queue\n");
1533 while ((req = elv_next_request(q)) != NULL)
1534 scsi_kill_request(req, q);
1538 if(!get_device(&sdev->sdev_gendev))
1539 /* We must be tearing the block queue down already */
1543 * To start with, we keep looping until the queue is empty, or until
1544 * the host is no longer able to accept any more requests.
1547 while (!blk_queue_plugged(q)) {
1550 * get next queueable request. We do this early to make sure
1551 * that the request is fully prepared even if we cannot
1554 req = elv_next_request(q);
1555 if (!req || !scsi_dev_queue_ready(q, sdev))
1558 if (unlikely(!scsi_device_online(sdev))) {
1559 sdev_printk(KERN_ERR, sdev,
1560 "rejecting I/O to offline device\n");
1561 scsi_kill_request(req, q);
1567 * Remove the request from the request list.
1569 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1570 blkdev_dequeue_request(req);
1571 sdev->device_busy++;
1573 spin_unlock(q->queue_lock);
1575 if (unlikely(cmd == NULL)) {
1576 printk(KERN_CRIT "impossible request in %s.\n"
1577 "please mail a stack trace to "
1578 "linux-scsi@vger.kernel.org",
1582 spin_lock(shost->host_lock);
1584 if (!scsi_host_queue_ready(q, shost, sdev))
1586 if (sdev->single_lun) {
1587 if (scsi_target(sdev)->starget_sdev_user &&
1588 scsi_target(sdev)->starget_sdev_user != sdev)
1590 scsi_target(sdev)->starget_sdev_user = sdev;
1595 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1596 * take the lock again.
1598 spin_unlock_irq(shost->host_lock);
1601 * Finally, initialize any error handling parameters, and set up
1602 * the timers for timeouts.
1604 scsi_init_cmd_errh(cmd);
1607 * Dispatch the command to the low-level driver.
1609 rtn = scsi_dispatch_cmd(cmd);
1610 spin_lock_irq(q->queue_lock);
1612 /* we're refusing the command; because of
1613 * the way locks get dropped, we need to
1614 * check here if plugging is required */
1615 if(sdev->device_busy == 0)
1625 spin_unlock_irq(shost->host_lock);
1628 * lock q, handle tag, requeue req, and decrement device_busy. We
1629 * must return with queue_lock held.
1631 * Decrementing device_busy without checking it is OK, as all such
1632 * cases (host limits or settings) should run the queue at some
1635 spin_lock_irq(q->queue_lock);
1636 blk_requeue_request(q, req);
1637 sdev->device_busy--;
1638 if(sdev->device_busy == 0)
1641 /* must be careful here...if we trigger the ->remove() function
1642 * we cannot be holding the q lock */
1643 spin_unlock_irq(q->queue_lock);
1644 put_device(&sdev->sdev_gendev);
1645 spin_lock_irq(q->queue_lock);
1648 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1650 struct device *host_dev;
1651 u64 bounce_limit = 0xffffffff;
1653 if (shost->unchecked_isa_dma)
1654 return BLK_BOUNCE_ISA;
1656 * Platforms with virtual-DMA translation
1657 * hardware have no practical limit.
1659 if (!PCI_DMA_BUS_IS_PHYS)
1660 return BLK_BOUNCE_ANY;
1662 host_dev = scsi_get_device(shost);
1663 if (host_dev && host_dev->dma_mask)
1664 bounce_limit = *host_dev->dma_mask;
1666 return bounce_limit;
1668 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1670 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1672 struct Scsi_Host *shost = sdev->host;
1673 struct request_queue *q;
1675 q = blk_init_queue(scsi_request_fn, NULL);
1679 blk_queue_prep_rq(q, scsi_prep_fn);
1681 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1682 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1683 blk_queue_max_sectors(q, shost->max_sectors);
1684 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1685 blk_queue_segment_boundary(q, shost->dma_boundary);
1686 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1689 * ordered tags are superior to flush ordering
1691 if (shost->ordered_tag)
1692 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1693 else if (shost->ordered_flush) {
1694 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1695 q->prepare_flush_fn = scsi_prepare_flush_fn;
1696 q->end_flush_fn = scsi_end_flush_fn;
1699 if (!shost->use_clustering)
1700 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1704 void scsi_free_queue(struct request_queue *q)
1706 blk_cleanup_queue(q);
1710 * Function: scsi_block_requests()
1712 * Purpose: Utility function used by low-level drivers to prevent further
1713 * commands from being queued to the device.
1715 * Arguments: shost - Host in question
1719 * Lock status: No locks are assumed held.
1721 * Notes: There is no timer nor any other means by which the requests
1722 * get unblocked other than the low-level driver calling
1723 * scsi_unblock_requests().
1725 void scsi_block_requests(struct Scsi_Host *shost)
1727 shost->host_self_blocked = 1;
1729 EXPORT_SYMBOL(scsi_block_requests);
1732 * Function: scsi_unblock_requests()
1734 * Purpose: Utility function used by low-level drivers to allow further
1735 * commands from being queued to the device.
1737 * Arguments: shost - Host in question
1741 * Lock status: No locks are assumed held.
1743 * Notes: There is no timer nor any other means by which the requests
1744 * get unblocked other than the low-level driver calling
1745 * scsi_unblock_requests().
1747 * This is done as an API function so that changes to the
1748 * internals of the scsi mid-layer won't require wholesale
1749 * changes to drivers that use this feature.
1751 void scsi_unblock_requests(struct Scsi_Host *shost)
1753 shost->host_self_blocked = 0;
1754 scsi_run_host_queues(shost);
1756 EXPORT_SYMBOL(scsi_unblock_requests);
1758 int __init scsi_init_queue(void)
1762 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1763 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1764 int size = sgp->size * sizeof(struct scatterlist);
1766 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1767 SLAB_HWCACHE_ALIGN, NULL, NULL);
1769 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1773 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1774 mempool_alloc_slab, mempool_free_slab,
1777 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1785 void scsi_exit_queue(void)
1789 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1790 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1791 mempool_destroy(sgp->pool);
1792 kmem_cache_destroy(sgp->slab);
1796 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1797 * six bytes if necessary.
1798 * @sdev: SCSI device to be queried
1799 * @dbd: set if mode sense will allow block descriptors to be returned
1800 * @modepage: mode page being requested
1801 * @buffer: request buffer (may not be smaller than eight bytes)
1802 * @len: length of request buffer.
1803 * @timeout: command timeout
1804 * @retries: number of retries before failing
1805 * @data: returns a structure abstracting the mode header data
1806 * @sense: place to put sense data (or NULL if no sense to be collected).
1807 * must be SCSI_SENSE_BUFFERSIZE big.
1809 * Returns zero if unsuccessful, or the header offset (either 4
1810 * or 8 depending on whether a six or ten byte command was
1811 * issued) if successful.
1814 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1815 unsigned char *buffer, int len, int timeout, int retries,
1816 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) {
1817 unsigned char cmd[12];
1821 struct scsi_sense_hdr my_sshdr;
1823 memset(data, 0, sizeof(*data));
1824 memset(&cmd[0], 0, 12);
1825 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1828 /* caller might not be interested in sense, but we need it */
1833 use_10_for_ms = sdev->use_10_for_ms;
1835 if (use_10_for_ms) {
1839 cmd[0] = MODE_SENSE_10;
1846 cmd[0] = MODE_SENSE;
1851 memset(buffer, 0, len);
1853 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1854 sshdr, timeout, retries);
1856 /* This code looks awful: what it's doing is making sure an
1857 * ILLEGAL REQUEST sense return identifies the actual command
1858 * byte as the problem. MODE_SENSE commands can return
1859 * ILLEGAL REQUEST if the code page isn't supported */
1861 if (use_10_for_ms && !scsi_status_is_good(result) &&
1862 (driver_byte(result) & DRIVER_SENSE)) {
1863 if (scsi_sense_valid(sshdr)) {
1864 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1865 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1867 * Invalid command operation code
1869 sdev->use_10_for_ms = 0;
1875 if(scsi_status_is_good(result)) {
1876 data->header_length = header_length;
1878 data->length = buffer[0]*256 + buffer[1] + 2;
1879 data->medium_type = buffer[2];
1880 data->device_specific = buffer[3];
1881 data->longlba = buffer[4] & 0x01;
1882 data->block_descriptor_length = buffer[6]*256
1885 data->length = buffer[0] + 1;
1886 data->medium_type = buffer[1];
1887 data->device_specific = buffer[2];
1888 data->block_descriptor_length = buffer[3];
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
2011 sdev->sdev_state = state;
2015 SCSI_LOG_ERROR_RECOVERY(1,
2016 sdev_printk(KERN_ERR, sdev,
2017 "Illegal state transition %s->%s\n",
2018 scsi_device_state_name(oldstate),
2019 scsi_device_state_name(state))
2023 EXPORT_SYMBOL(scsi_device_set_state);
2026 * scsi_device_quiesce - Block user issued commands.
2027 * @sdev: scsi device to quiesce.
2029 * This works by trying to transition to the SDEV_QUIESCE state
2030 * (which must be a legal transition). When the device is in this
2031 * state, only special requests will be accepted, all others will
2032 * be deferred. Since special requests may also be requeued requests,
2033 * a successful return doesn't guarantee the device will be
2034 * totally quiescent.
2036 * Must be called with user context, may sleep.
2038 * Returns zero if unsuccessful or an error if not.
2041 scsi_device_quiesce(struct scsi_device *sdev)
2043 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2047 scsi_run_queue(sdev->request_queue);
2048 while (sdev->device_busy) {
2049 msleep_interruptible(200);
2050 scsi_run_queue(sdev->request_queue);
2054 EXPORT_SYMBOL(scsi_device_quiesce);
2057 * scsi_device_resume - Restart user issued commands to a quiesced device.
2058 * @sdev: scsi device to resume.
2060 * Moves the device from quiesced back to running and restarts the
2063 * Must be called with user context, may sleep.
2066 scsi_device_resume(struct scsi_device *sdev)
2068 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2070 scsi_run_queue(sdev->request_queue);
2072 EXPORT_SYMBOL(scsi_device_resume);
2075 device_quiesce_fn(struct scsi_device *sdev, void *data)
2077 scsi_device_quiesce(sdev);
2081 scsi_target_quiesce(struct scsi_target *starget)
2083 starget_for_each_device(starget, NULL, device_quiesce_fn);
2085 EXPORT_SYMBOL(scsi_target_quiesce);
2088 device_resume_fn(struct scsi_device *sdev, void *data)
2090 scsi_device_resume(sdev);
2094 scsi_target_resume(struct scsi_target *starget)
2096 starget_for_each_device(starget, NULL, device_resume_fn);
2098 EXPORT_SYMBOL(scsi_target_resume);
2101 * scsi_internal_device_block - internal function to put a device
2102 * temporarily into the SDEV_BLOCK state
2103 * @sdev: device to block
2105 * Block request made by scsi lld's to temporarily stop all
2106 * scsi commands on the specified device. Called from interrupt
2107 * or normal process context.
2109 * Returns zero if successful or error if not
2112 * This routine transitions the device to the SDEV_BLOCK state
2113 * (which must be a legal transition). When the device is in this
2114 * state, all commands are deferred until the scsi lld reenables
2115 * the device with scsi_device_unblock or device_block_tmo fires.
2116 * This routine assumes the host_lock is held on entry.
2119 scsi_internal_device_block(struct scsi_device *sdev)
2121 request_queue_t *q = sdev->request_queue;
2122 unsigned long flags;
2125 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2130 * The device has transitioned to SDEV_BLOCK. Stop the
2131 * block layer from calling the midlayer with this device's
2134 spin_lock_irqsave(q->queue_lock, flags);
2136 spin_unlock_irqrestore(q->queue_lock, flags);
2140 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2143 * scsi_internal_device_unblock - resume a device after a block request
2144 * @sdev: device to resume
2146 * Called by scsi lld's or the midlayer to restart the device queue
2147 * for the previously suspended scsi device. Called from interrupt or
2148 * normal process context.
2150 * Returns zero if successful or error if not.
2153 * This routine transitions the device to the SDEV_RUNNING state
2154 * (which must be a legal transition) allowing the midlayer to
2155 * goose the queue for this device. This routine assumes the
2156 * host_lock is held upon entry.
2159 scsi_internal_device_unblock(struct scsi_device *sdev)
2161 request_queue_t *q = sdev->request_queue;
2163 unsigned long flags;
2166 * Try to transition the scsi device to SDEV_RUNNING
2167 * and goose the device queue if successful.
2169 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2173 spin_lock_irqsave(q->queue_lock, flags);
2175 spin_unlock_irqrestore(q->queue_lock, flags);
2179 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2182 device_block(struct scsi_device *sdev, void *data)
2184 scsi_internal_device_block(sdev);
2188 target_block(struct device *dev, void *data)
2190 if (scsi_is_target_device(dev))
2191 starget_for_each_device(to_scsi_target(dev), NULL,
2197 scsi_target_block(struct device *dev)
2199 if (scsi_is_target_device(dev))
2200 starget_for_each_device(to_scsi_target(dev), NULL,
2203 device_for_each_child(dev, NULL, target_block);
2205 EXPORT_SYMBOL_GPL(scsi_target_block);
2208 device_unblock(struct scsi_device *sdev, void *data)
2210 scsi_internal_device_unblock(sdev);
2214 target_unblock(struct device *dev, void *data)
2216 if (scsi_is_target_device(dev))
2217 starget_for_each_device(to_scsi_target(dev), NULL,
2223 scsi_target_unblock(struct device *dev)
2225 if (scsi_is_target_device(dev))
2226 starget_for_each_device(to_scsi_target(dev), NULL,
2229 device_for_each_child(dev, NULL, target_unblock);
2231 EXPORT_SYMBOL_GPL(scsi_target_unblock);