2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/completion.h>
13 #include <linux/kernel.h>
14 #include <linux/mempool.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/pci.h>
18 #include <linux/delay.h>
19 #include <linux/hardirq.h>
20 #include <linux/scatterlist.h>
22 #include <scsi/scsi.h>
23 #include <scsi/scsi_cmnd.h>
24 #include <scsi/scsi_dbg.h>
25 #include <scsi/scsi_device.h>
26 #include <scsi/scsi_driver.h>
27 #include <scsi/scsi_eh.h>
28 #include <scsi/scsi_host.h>
30 #include "scsi_priv.h"
31 #include "scsi_logging.h"
34 #define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
35 #define SG_MEMPOOL_SIZE 2
38 * The maximum number of SG segments that we will put inside a scatterlist
39 * (unless chaining is used). Should ideally fit inside a single page, to
40 * avoid a higher order allocation.
42 #define SCSI_MAX_SG_SEGMENTS 128
44 struct scsi_host_sg_pool {
47 struct kmem_cache *slab;
51 #define SP(x) { x, "sgpool-" #x }
52 static struct scsi_host_sg_pool scsi_sg_pools[] = {
55 #if (SCSI_MAX_SG_SEGMENTS > 16)
57 #if (SCSI_MAX_SG_SEGMENTS > 32)
59 #if (SCSI_MAX_SG_SEGMENTS > 64)
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 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);
266 return blk_rq_append_bio(q, rq, bio);
269 static void scsi_bi_endio(struct bio *bio, int error)
275 * scsi_req_map_sg - map a scatterlist into a request
276 * @rq: request to fill
278 * @nsegs: number of elements
279 * @bufflen: len of buffer
280 * @gfp: memory allocation flags
282 * scsi_req_map_sg maps a scatterlist into a request so that the
283 * request can be sent to the block layer. We do not trust the scatterlist
284 * sent to use, as some ULDs use that struct to only organize the pages.
286 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
287 int nsegs, unsigned bufflen, gfp_t gfp)
289 struct request_queue *q = rq->q;
290 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
291 unsigned int data_len = bufflen, len, bytes, off;
292 struct scatterlist *sg;
294 struct bio *bio = NULL;
295 int i, err, nr_vecs = 0;
297 for_each_sg(sgl, sg, nsegs, i) {
303 while (len > 0 && data_len > 0) {
305 * sg sends a scatterlist that is larger than
306 * the data_len it wants transferred for certain
309 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
310 bytes = min(bytes, data_len);
313 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
316 bio = bio_alloc(gfp, nr_vecs);
321 bio->bi_end_io = scsi_bi_endio;
324 if (bio_add_pc_page(q, bio, page, bytes, off) !=
331 if (bio->bi_vcnt >= nr_vecs) {
332 err = scsi_merge_bio(rq, bio);
347 rq->buffer = rq->data = NULL;
348 rq->data_len = bufflen;
352 while ((bio = rq->bio) != NULL) {
353 rq->bio = bio->bi_next;
355 * call endio instead of bio_put incase it was bounced
364 * scsi_execute_async - insert request
367 * @cmd_len: length of scsi cdb
368 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
369 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
370 * @bufflen: len of buffer
371 * @use_sg: if buffer is a scatterlist this is the number of elements
372 * @timeout: request timeout in seconds
373 * @retries: number of times to retry request
374 * @privdata: data passed to done()
375 * @done: callback function when done
376 * @gfp: memory allocation flags
378 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
379 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
380 int use_sg, int timeout, int retries, void *privdata,
381 void (*done)(void *, char *, int, int), gfp_t gfp)
384 struct scsi_io_context *sioc;
386 int write = (data_direction == DMA_TO_DEVICE);
388 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
390 return DRIVER_ERROR << 24;
392 req = blk_get_request(sdev->request_queue, write, gfp);
395 req->cmd_type = REQ_TYPE_BLOCK_PC;
396 req->cmd_flags |= REQ_QUIET;
399 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
401 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
406 req->cmd_len = cmd_len;
407 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
408 memcpy(req->cmd, cmd, req->cmd_len);
409 req->sense = sioc->sense;
411 req->timeout = timeout;
412 req->retries = retries;
413 req->end_io_data = sioc;
415 sioc->data = privdata;
418 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
422 blk_put_request(req);
424 kmem_cache_free(scsi_io_context_cache, sioc);
425 return DRIVER_ERROR << 24;
427 EXPORT_SYMBOL_GPL(scsi_execute_async);
430 * Function: scsi_init_cmd_errh()
432 * Purpose: Initialize cmd fields related to error handling.
434 * Arguments: cmd - command that is ready to be queued.
436 * Notes: This function has the job of initializing a number of
437 * fields related to error handling. Typically this will
438 * be called once for each command, as required.
440 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
442 cmd->serial_number = 0;
444 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
445 if (cmd->cmd_len == 0)
446 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
449 void scsi_device_unbusy(struct scsi_device *sdev)
451 struct Scsi_Host *shost = sdev->host;
454 spin_lock_irqsave(shost->host_lock, flags);
456 if (unlikely(scsi_host_in_recovery(shost) &&
457 (shost->host_failed || shost->host_eh_scheduled)))
458 scsi_eh_wakeup(shost);
459 spin_unlock(shost->host_lock);
460 spin_lock(sdev->request_queue->queue_lock);
462 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
466 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
467 * and call blk_run_queue for all the scsi_devices on the target -
468 * including current_sdev first.
470 * Called with *no* scsi locks held.
472 static void scsi_single_lun_run(struct scsi_device *current_sdev)
474 struct Scsi_Host *shost = current_sdev->host;
475 struct scsi_device *sdev, *tmp;
476 struct scsi_target *starget = scsi_target(current_sdev);
479 spin_lock_irqsave(shost->host_lock, flags);
480 starget->starget_sdev_user = NULL;
481 spin_unlock_irqrestore(shost->host_lock, flags);
484 * Call blk_run_queue for all LUNs on the target, starting with
485 * current_sdev. We race with others (to set starget_sdev_user),
486 * but in most cases, we will be first. Ideally, each LU on the
487 * target would get some limited time or requests on the target.
489 blk_run_queue(current_sdev->request_queue);
491 spin_lock_irqsave(shost->host_lock, flags);
492 if (starget->starget_sdev_user)
494 list_for_each_entry_safe(sdev, tmp, &starget->devices,
495 same_target_siblings) {
496 if (sdev == current_sdev)
498 if (scsi_device_get(sdev))
501 spin_unlock_irqrestore(shost->host_lock, flags);
502 blk_run_queue(sdev->request_queue);
503 spin_lock_irqsave(shost->host_lock, flags);
505 scsi_device_put(sdev);
508 spin_unlock_irqrestore(shost->host_lock, flags);
512 * Function: scsi_run_queue()
514 * Purpose: Select a proper request queue to serve next
516 * Arguments: q - last request's queue
520 * Notes: The previous command was completely finished, start
521 * a new one if possible.
523 static void scsi_run_queue(struct request_queue *q)
525 struct scsi_device *sdev = q->queuedata;
526 struct Scsi_Host *shost = sdev->host;
529 if (scsi_target(sdev)->single_lun)
530 scsi_single_lun_run(sdev);
532 spin_lock_irqsave(shost->host_lock, flags);
533 while (!list_empty(&shost->starved_list) &&
534 !shost->host_blocked && !shost->host_self_blocked &&
535 !((shost->can_queue > 0) &&
536 (shost->host_busy >= shost->can_queue))) {
538 * As long as shost is accepting commands and we have
539 * starved queues, call blk_run_queue. scsi_request_fn
540 * drops the queue_lock and can add us back to the
543 * host_lock protects the starved_list and starved_entry.
544 * scsi_request_fn must get the host_lock before checking
545 * or modifying starved_list or starved_entry.
547 sdev = list_entry(shost->starved_list.next,
548 struct scsi_device, starved_entry);
549 list_del_init(&sdev->starved_entry);
550 spin_unlock_irqrestore(shost->host_lock, flags);
553 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
554 !test_and_set_bit(QUEUE_FLAG_REENTER,
555 &sdev->request_queue->queue_flags)) {
556 blk_run_queue(sdev->request_queue);
557 clear_bit(QUEUE_FLAG_REENTER,
558 &sdev->request_queue->queue_flags);
560 blk_run_queue(sdev->request_queue);
562 spin_lock_irqsave(shost->host_lock, flags);
563 if (unlikely(!list_empty(&sdev->starved_entry)))
565 * sdev lost a race, and was put back on the
566 * starved list. This is unlikely but without this
567 * in theory we could loop forever.
571 spin_unlock_irqrestore(shost->host_lock, flags);
577 * Function: scsi_requeue_command()
579 * Purpose: Handle post-processing of completed commands.
581 * Arguments: q - queue to operate on
582 * cmd - command that may need to be requeued.
586 * Notes: After command completion, there may be blocks left
587 * over which weren't finished by the previous command
588 * this can be for a number of reasons - the main one is
589 * I/O errors in the middle of the request, in which case
590 * we need to request the blocks that come after the bad
592 * Notes: Upon return, cmd is a stale pointer.
594 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
596 struct request *req = cmd->request;
599 scsi_unprep_request(req);
600 spin_lock_irqsave(q->queue_lock, flags);
601 blk_requeue_request(q, req);
602 spin_unlock_irqrestore(q->queue_lock, flags);
607 void scsi_next_command(struct scsi_cmnd *cmd)
609 struct scsi_device *sdev = cmd->device;
610 struct request_queue *q = sdev->request_queue;
612 /* need to hold a reference on the device before we let go of the cmd */
613 get_device(&sdev->sdev_gendev);
615 scsi_put_command(cmd);
618 /* ok to remove device now */
619 put_device(&sdev->sdev_gendev);
622 void scsi_run_host_queues(struct Scsi_Host *shost)
624 struct scsi_device *sdev;
626 shost_for_each_device(sdev, shost)
627 scsi_run_queue(sdev->request_queue);
631 * Function: scsi_end_request()
633 * Purpose: Post-processing of completed commands (usually invoked at end
634 * of upper level post-processing and scsi_io_completion).
636 * Arguments: cmd - command that is complete.
637 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
638 * bytes - number of bytes of completed I/O
639 * requeue - indicates whether we should requeue leftovers.
641 * Lock status: Assumed that lock is not held upon entry.
643 * Returns: cmd if requeue required, NULL otherwise.
645 * Notes: This is called for block device requests in order to
646 * mark some number of sectors as complete.
648 * We are guaranteeing that the request queue will be goosed
649 * at some point during this call.
650 * Notes: If cmd was requeued, upon return it will be a stale pointer.
652 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
653 int bytes, int requeue)
655 struct request_queue *q = cmd->device->request_queue;
656 struct request *req = cmd->request;
660 * If there are blocks left over at the end, set up the command
661 * to queue the remainder of them.
663 if (end_that_request_chunk(req, uptodate, bytes)) {
664 int leftover = (req->hard_nr_sectors << 9);
666 if (blk_pc_request(req))
667 leftover = req->data_len;
669 /* kill remainder if no retrys */
670 if (!uptodate && blk_noretry_request(req))
671 end_that_request_chunk(req, 0, leftover);
675 * Bleah. Leftovers again. Stick the
676 * leftovers in the front of the
677 * queue, and goose the queue again.
679 scsi_requeue_command(q, cmd);
686 add_disk_randomness(req->rq_disk);
688 spin_lock_irqsave(q->queue_lock, flags);
689 if (blk_rq_tagged(req))
690 blk_queue_end_tag(q, req);
691 end_that_request_last(req, uptodate);
692 spin_unlock_irqrestore(q->queue_lock, flags);
695 * This will goose the queue request function at the end, so we don't
696 * need to worry about launching another command.
698 scsi_next_command(cmd);
703 * Like SCSI_MAX_SG_SEGMENTS, but for archs that have sg chaining. This limit
704 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
706 #define SCSI_MAX_SG_CHAIN_SEGMENTS 2048
708 static inline unsigned int scsi_sgtable_index(unsigned short nents)
719 #if (SCSI_MAX_SG_SEGMENTS > 16)
723 #if (SCSI_MAX_SG_SEGMENTS > 32)
727 #if (SCSI_MAX_SG_SEGMENTS > 64)
735 printk(KERN_ERR "scsi: bad segment count=%d\n", nents);
742 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
744 struct scsi_host_sg_pool *sgp;
746 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
747 mempool_free(sgl, sgp->pool);
750 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
752 struct scsi_host_sg_pool *sgp;
754 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
755 return mempool_alloc(sgp->pool, gfp_mask);
758 int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
762 BUG_ON(!cmd->use_sg);
764 ret = __sg_alloc_table(&cmd->sg_table, cmd->use_sg, gfp_mask, scsi_sg_alloc);
766 __sg_free_table(&cmd->sg_table, scsi_sg_free);
768 cmd->request_buffer = cmd->sg_table.sgl;
772 EXPORT_SYMBOL(scsi_alloc_sgtable);
774 void scsi_free_sgtable(struct scsi_cmnd *cmd)
776 __sg_free_table(&cmd->sg_table, scsi_sg_free);
779 EXPORT_SYMBOL(scsi_free_sgtable);
782 * Function: scsi_release_buffers()
784 * Purpose: Completion processing for block device I/O requests.
786 * Arguments: cmd - command that we are bailing.
788 * Lock status: Assumed that no lock is held upon entry.
792 * Notes: In the event that an upper level driver rejects a
793 * command, we must release resources allocated during
794 * the __init_io() function. Primarily this would involve
795 * the scatter-gather table, and potentially any bounce
798 static void scsi_release_buffers(struct scsi_cmnd *cmd)
801 scsi_free_sgtable(cmd);
804 * Zero these out. They now point to freed memory, and it is
805 * dangerous to hang onto the pointers.
807 cmd->request_buffer = NULL;
808 cmd->request_bufflen = 0;
812 * Function: scsi_io_completion()
814 * Purpose: Completion processing for block device I/O requests.
816 * Arguments: cmd - command that is finished.
818 * Lock status: Assumed that no lock is held upon entry.
822 * Notes: This function is matched in terms of capabilities to
823 * the function that created the scatter-gather list.
824 * In other words, if there are no bounce buffers
825 * (the normal case for most drivers), we don't need
826 * the logic to deal with cleaning up afterwards.
828 * We must do one of several things here:
830 * a) Call scsi_end_request. This will finish off the
831 * specified number of sectors. If we are done, the
832 * command block will be released, and the queue
833 * function will be goosed. If we are not done, then
834 * scsi_end_request will directly goose the queue.
836 * b) We can just use scsi_requeue_command() here. This would
837 * be used if we just wanted to retry, for example.
839 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
841 int result = cmd->result;
842 int this_count = cmd->request_bufflen;
843 struct request_queue *q = cmd->device->request_queue;
844 struct request *req = cmd->request;
845 int clear_errors = 1;
846 struct scsi_sense_hdr sshdr;
848 int sense_deferred = 0;
850 scsi_release_buffers(cmd);
853 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
855 sense_deferred = scsi_sense_is_deferred(&sshdr);
858 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
859 req->errors = result;
862 if (sense_valid && req->sense) {
864 * SG_IO wants current and deferred errors
866 int len = 8 + cmd->sense_buffer[7];
868 if (len > SCSI_SENSE_BUFFERSIZE)
869 len = SCSI_SENSE_BUFFERSIZE;
870 memcpy(req->sense, cmd->sense_buffer, len);
871 req->sense_len = len;
874 req->data_len = cmd->resid;
878 * Next deal with any sectors which we were able to correctly
881 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
883 req->nr_sectors, good_bytes));
884 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
889 /* A number of bytes were successfully read. If there
890 * are leftovers and there is some kind of error
891 * (result != 0), retry the rest.
893 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
896 /* good_bytes = 0, or (inclusive) there were leftovers and
897 * result = 0, so scsi_end_request couldn't retry.
899 if (sense_valid && !sense_deferred) {
900 switch (sshdr.sense_key) {
902 if (cmd->device->removable) {
903 /* Detected disc change. Set a bit
904 * and quietly refuse further access.
906 cmd->device->changed = 1;
907 scsi_end_request(cmd, 0, this_count, 1);
910 /* Must have been a power glitch, or a
911 * bus reset. Could not have been a
912 * media change, so we just retry the
913 * request and see what happens.
915 scsi_requeue_command(q, cmd);
919 case ILLEGAL_REQUEST:
920 /* If we had an ILLEGAL REQUEST returned, then
921 * we may have performed an unsupported
922 * command. The only thing this should be
923 * would be a ten byte read where only a six
924 * byte read was supported. Also, on a system
925 * where READ CAPACITY failed, we may have
926 * read past the end of the disk.
928 if ((cmd->device->use_10_for_rw &&
929 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
930 (cmd->cmnd[0] == READ_10 ||
931 cmd->cmnd[0] == WRITE_10)) {
932 cmd->device->use_10_for_rw = 0;
933 /* This will cause a retry with a
936 scsi_requeue_command(q, cmd);
939 scsi_end_request(cmd, 0, this_count, 1);
944 /* If the device is in the process of becoming
945 * ready, or has a temporary blockage, retry.
947 if (sshdr.asc == 0x04) {
948 switch (sshdr.ascq) {
949 case 0x01: /* becoming ready */
950 case 0x04: /* format in progress */
951 case 0x05: /* rebuild in progress */
952 case 0x06: /* recalculation in progress */
953 case 0x07: /* operation in progress */
954 case 0x08: /* Long write in progress */
955 case 0x09: /* self test in progress */
956 scsi_requeue_command(q, cmd);
962 if (!(req->cmd_flags & REQ_QUIET))
963 scsi_cmd_print_sense_hdr(cmd,
967 scsi_end_request(cmd, 0, this_count, 1);
969 case VOLUME_OVERFLOW:
970 if (!(req->cmd_flags & REQ_QUIET)) {
971 scmd_printk(KERN_INFO, cmd,
972 "Volume overflow, CDB: ");
973 __scsi_print_command(cmd->cmnd);
974 scsi_print_sense("", cmd);
976 /* See SSC3rXX or current. */
977 scsi_end_request(cmd, 0, this_count, 1);
983 if (host_byte(result) == DID_RESET) {
984 /* Third party bus reset or reset for error recovery
985 * reasons. Just retry the request and see what
988 scsi_requeue_command(q, cmd);
992 if (!(req->cmd_flags & REQ_QUIET)) {
993 scsi_print_result(cmd);
994 if (driver_byte(result) & DRIVER_SENSE)
995 scsi_print_sense("", cmd);
998 scsi_end_request(cmd, 0, this_count, !result);
1002 * Function: scsi_init_io()
1004 * Purpose: SCSI I/O initialize function.
1006 * Arguments: cmd - Command descriptor we wish to initialize
1008 * Returns: 0 on success
1009 * BLKPREP_DEFER if the failure is retryable
1011 static int scsi_init_io(struct scsi_cmnd *cmd)
1013 struct request *req = cmd->request;
1017 * We used to not use scatter-gather for single segment request,
1018 * but now we do (it makes highmem I/O easier to support without
1021 cmd->use_sg = req->nr_phys_segments;
1024 * If sg table allocation fails, requeue request later.
1026 if (unlikely(scsi_alloc_sgtable(cmd, GFP_ATOMIC))) {
1027 scsi_unprep_request(req);
1028 return BLKPREP_DEFER;
1032 if (blk_pc_request(req))
1033 cmd->request_bufflen = req->data_len;
1035 cmd->request_bufflen = req->nr_sectors << 9;
1038 * Next, walk the list, and fill in the addresses and sizes of
1041 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
1042 BUG_ON(count > cmd->use_sg);
1043 cmd->use_sg = count;
1047 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1048 struct request *req)
1050 struct scsi_cmnd *cmd;
1052 if (!req->special) {
1053 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1061 /* pull a tag out of the request if we have one */
1062 cmd->tag = req->tag;
1068 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1070 struct scsi_cmnd *cmd;
1071 int ret = scsi_prep_state_check(sdev, req);
1073 if (ret != BLKPREP_OK)
1076 cmd = scsi_get_cmd_from_req(sdev, req);
1078 return BLKPREP_DEFER;
1081 * BLOCK_PC requests may transfer data, in which case they must
1082 * a bio attached to them. Or they might contain a SCSI command
1083 * that does not transfer data, in which case they may optionally
1084 * submit a request without an attached bio.
1089 BUG_ON(!req->nr_phys_segments);
1091 ret = scsi_init_io(cmd);
1095 BUG_ON(req->data_len);
1098 cmd->request_bufflen = 0;
1099 cmd->request_buffer = NULL;
1104 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
1105 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1106 cmd->cmd_len = req->cmd_len;
1108 cmd->sc_data_direction = DMA_NONE;
1109 else if (rq_data_dir(req) == WRITE)
1110 cmd->sc_data_direction = DMA_TO_DEVICE;
1112 cmd->sc_data_direction = DMA_FROM_DEVICE;
1114 cmd->transfersize = req->data_len;
1115 cmd->allowed = req->retries;
1116 cmd->timeout_per_command = req->timeout;
1119 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1122 * Setup a REQ_TYPE_FS command. These are simple read/write request
1123 * from filesystems that still need to be translated to SCSI CDBs from
1126 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1128 struct scsi_cmnd *cmd;
1129 int ret = scsi_prep_state_check(sdev, req);
1131 if (ret != BLKPREP_OK)
1134 * Filesystem requests must transfer data.
1136 BUG_ON(!req->nr_phys_segments);
1138 cmd = scsi_get_cmd_from_req(sdev, req);
1140 return BLKPREP_DEFER;
1142 return scsi_init_io(cmd);
1144 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1146 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1148 int ret = BLKPREP_OK;
1151 * If the device is not in running state we will reject some
1154 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1155 switch (sdev->sdev_state) {
1158 * If the device is offline we refuse to process any
1159 * commands. The device must be brought online
1160 * before trying any recovery commands.
1162 sdev_printk(KERN_ERR, sdev,
1163 "rejecting I/O to offline device\n");
1168 * If the device is fully deleted, we refuse to
1169 * process any commands as well.
1171 sdev_printk(KERN_ERR, sdev,
1172 "rejecting I/O to dead device\n");
1178 * If the devices is blocked we defer normal commands.
1180 if (!(req->cmd_flags & REQ_PREEMPT))
1181 ret = BLKPREP_DEFER;
1185 * For any other not fully online state we only allow
1186 * special commands. In particular any user initiated
1187 * command is not allowed.
1189 if (!(req->cmd_flags & REQ_PREEMPT))
1196 EXPORT_SYMBOL(scsi_prep_state_check);
1198 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1200 struct scsi_device *sdev = q->queuedata;
1204 req->errors = DID_NO_CONNECT << 16;
1205 /* release the command and kill it */
1207 struct scsi_cmnd *cmd = req->special;
1208 scsi_release_buffers(cmd);
1209 scsi_put_command(cmd);
1210 req->special = NULL;
1215 * If we defer, the elv_next_request() returns NULL, but the
1216 * queue must be restarted, so we plug here if no returning
1217 * command will automatically do that.
1219 if (sdev->device_busy == 0)
1223 req->cmd_flags |= REQ_DONTPREP;
1228 EXPORT_SYMBOL(scsi_prep_return);
1230 int scsi_prep_fn(struct request_queue *q, struct request *req)
1232 struct scsi_device *sdev = q->queuedata;
1233 int ret = BLKPREP_KILL;
1235 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1236 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1237 return scsi_prep_return(q, req, ret);
1241 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1244 * Called with the queue_lock held.
1246 static inline int scsi_dev_queue_ready(struct request_queue *q,
1247 struct scsi_device *sdev)
1249 if (sdev->device_busy >= sdev->queue_depth)
1251 if (sdev->device_busy == 0 && sdev->device_blocked) {
1253 * unblock after device_blocked iterates to zero
1255 if (--sdev->device_blocked == 0) {
1257 sdev_printk(KERN_INFO, sdev,
1258 "unblocking device at zero depth\n"));
1264 if (sdev->device_blocked)
1271 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1272 * return 0. We must end up running the queue again whenever 0 is
1273 * returned, else IO can hang.
1275 * Called with host_lock held.
1277 static inline int scsi_host_queue_ready(struct request_queue *q,
1278 struct Scsi_Host *shost,
1279 struct scsi_device *sdev)
1281 if (scsi_host_in_recovery(shost))
1283 if (shost->host_busy == 0 && shost->host_blocked) {
1285 * unblock after host_blocked iterates to zero
1287 if (--shost->host_blocked == 0) {
1289 printk("scsi%d unblocking host at zero depth\n",
1296 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1297 shost->host_blocked || shost->host_self_blocked) {
1298 if (list_empty(&sdev->starved_entry))
1299 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1303 /* We're OK to process the command, so we can't be starved */
1304 if (!list_empty(&sdev->starved_entry))
1305 list_del_init(&sdev->starved_entry);
1311 * Kill a request for a dead device
1313 static void scsi_kill_request(struct request *req, struct request_queue *q)
1315 struct scsi_cmnd *cmd = req->special;
1316 struct scsi_device *sdev = cmd->device;
1317 struct Scsi_Host *shost = sdev->host;
1319 blkdev_dequeue_request(req);
1321 if (unlikely(cmd == NULL)) {
1322 printk(KERN_CRIT "impossible request in %s.\n",
1327 scsi_init_cmd_errh(cmd);
1328 cmd->result = DID_NO_CONNECT << 16;
1329 atomic_inc(&cmd->device->iorequest_cnt);
1332 * SCSI request completion path will do scsi_device_unbusy(),
1333 * bump busy counts. To bump the counters, we need to dance
1334 * with the locks as normal issue path does.
1336 sdev->device_busy++;
1337 spin_unlock(sdev->request_queue->queue_lock);
1338 spin_lock(shost->host_lock);
1340 spin_unlock(shost->host_lock);
1341 spin_lock(sdev->request_queue->queue_lock);
1346 static void scsi_softirq_done(struct request *rq)
1348 struct scsi_cmnd *cmd = rq->completion_data;
1349 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
1352 INIT_LIST_HEAD(&cmd->eh_entry);
1354 disposition = scsi_decide_disposition(cmd);
1355 if (disposition != SUCCESS &&
1356 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1357 sdev_printk(KERN_ERR, cmd->device,
1358 "timing out command, waited %lus\n",
1360 disposition = SUCCESS;
1363 scsi_log_completion(cmd, disposition);
1365 switch (disposition) {
1367 scsi_finish_command(cmd);
1370 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1372 case ADD_TO_MLQUEUE:
1373 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1376 if (!scsi_eh_scmd_add(cmd, 0))
1377 scsi_finish_command(cmd);
1382 * Function: scsi_request_fn()
1384 * Purpose: Main strategy routine for SCSI.
1386 * Arguments: q - Pointer to actual queue.
1390 * Lock status: IO request lock assumed to be held when called.
1392 static void scsi_request_fn(struct request_queue *q)
1394 struct scsi_device *sdev = q->queuedata;
1395 struct Scsi_Host *shost;
1396 struct scsi_cmnd *cmd;
1397 struct request *req;
1400 printk("scsi: killing requests for dead queue\n");
1401 while ((req = elv_next_request(q)) != NULL)
1402 scsi_kill_request(req, q);
1406 if(!get_device(&sdev->sdev_gendev))
1407 /* We must be tearing the block queue down already */
1411 * To start with, we keep looping until the queue is empty, or until
1412 * the host is no longer able to accept any more requests.
1415 while (!blk_queue_plugged(q)) {
1418 * get next queueable request. We do this early to make sure
1419 * that the request is fully prepared even if we cannot
1422 req = elv_next_request(q);
1423 if (!req || !scsi_dev_queue_ready(q, sdev))
1426 if (unlikely(!scsi_device_online(sdev))) {
1427 sdev_printk(KERN_ERR, sdev,
1428 "rejecting I/O to offline device\n");
1429 scsi_kill_request(req, q);
1435 * Remove the request from the request list.
1437 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1438 blkdev_dequeue_request(req);
1439 sdev->device_busy++;
1441 spin_unlock(q->queue_lock);
1443 if (unlikely(cmd == NULL)) {
1444 printk(KERN_CRIT "impossible request in %s.\n"
1445 "please mail a stack trace to "
1446 "linux-scsi@vger.kernel.org\n",
1448 blk_dump_rq_flags(req, "foo");
1451 spin_lock(shost->host_lock);
1453 if (!scsi_host_queue_ready(q, shost, sdev))
1455 if (scsi_target(sdev)->single_lun) {
1456 if (scsi_target(sdev)->starget_sdev_user &&
1457 scsi_target(sdev)->starget_sdev_user != sdev)
1459 scsi_target(sdev)->starget_sdev_user = sdev;
1464 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1465 * take the lock again.
1467 spin_unlock_irq(shost->host_lock);
1470 * Finally, initialize any error handling parameters, and set up
1471 * the timers for timeouts.
1473 scsi_init_cmd_errh(cmd);
1476 * Dispatch the command to the low-level driver.
1478 rtn = scsi_dispatch_cmd(cmd);
1479 spin_lock_irq(q->queue_lock);
1481 /* we're refusing the command; because of
1482 * the way locks get dropped, we need to
1483 * check here if plugging is required */
1484 if(sdev->device_busy == 0)
1494 spin_unlock_irq(shost->host_lock);
1497 * lock q, handle tag, requeue req, and decrement device_busy. We
1498 * must return with queue_lock held.
1500 * Decrementing device_busy without checking it is OK, as all such
1501 * cases (host limits or settings) should run the queue at some
1504 spin_lock_irq(q->queue_lock);
1505 blk_requeue_request(q, req);
1506 sdev->device_busy--;
1507 if(sdev->device_busy == 0)
1510 /* must be careful here...if we trigger the ->remove() function
1511 * we cannot be holding the q lock */
1512 spin_unlock_irq(q->queue_lock);
1513 put_device(&sdev->sdev_gendev);
1514 spin_lock_irq(q->queue_lock);
1517 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1519 struct device *host_dev;
1520 u64 bounce_limit = 0xffffffff;
1522 if (shost->unchecked_isa_dma)
1523 return BLK_BOUNCE_ISA;
1525 * Platforms with virtual-DMA translation
1526 * hardware have no practical limit.
1528 if (!PCI_DMA_BUS_IS_PHYS)
1529 return BLK_BOUNCE_ANY;
1531 host_dev = scsi_get_device(shost);
1532 if (host_dev && host_dev->dma_mask)
1533 bounce_limit = *host_dev->dma_mask;
1535 return bounce_limit;
1537 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1539 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1540 request_fn_proc *request_fn)
1542 struct request_queue *q;
1544 q = blk_init_queue(request_fn, NULL);
1549 * this limit is imposed by hardware restrictions
1551 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1554 * In the future, sg chaining support will be mandatory and this
1555 * ifdef can then go away. Right now we don't have all archs
1556 * converted, so better keep it safe.
1558 #ifdef ARCH_HAS_SG_CHAIN
1559 if (shost->use_sg_chaining)
1560 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1562 blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
1564 blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
1567 blk_queue_max_sectors(q, shost->max_sectors);
1568 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1569 blk_queue_segment_boundary(q, shost->dma_boundary);
1571 if (!shost->use_clustering)
1572 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1575 * set a reasonable default alignment on word boundaries: the
1576 * host and device may alter it using
1577 * blk_queue_update_dma_alignment() later.
1579 blk_queue_dma_alignment(q, 0x03);
1583 EXPORT_SYMBOL(__scsi_alloc_queue);
1585 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1587 struct request_queue *q;
1589 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1593 blk_queue_prep_rq(q, scsi_prep_fn);
1594 blk_queue_softirq_done(q, scsi_softirq_done);
1598 void scsi_free_queue(struct request_queue *q)
1600 blk_cleanup_queue(q);
1604 * Function: scsi_block_requests()
1606 * Purpose: Utility function used by low-level drivers to prevent further
1607 * commands from being queued to the device.
1609 * Arguments: shost - Host in question
1613 * Lock status: No locks are assumed held.
1615 * Notes: There is no timer nor any other means by which the requests
1616 * get unblocked other than the low-level driver calling
1617 * scsi_unblock_requests().
1619 void scsi_block_requests(struct Scsi_Host *shost)
1621 shost->host_self_blocked = 1;
1623 EXPORT_SYMBOL(scsi_block_requests);
1626 * Function: scsi_unblock_requests()
1628 * Purpose: Utility function used by low-level drivers to allow further
1629 * commands from being queued to the device.
1631 * Arguments: shost - Host in question
1635 * Lock status: No locks are assumed held.
1637 * Notes: There is no timer nor any other means by which the requests
1638 * get unblocked other than the low-level driver calling
1639 * scsi_unblock_requests().
1641 * This is done as an API function so that changes to the
1642 * internals of the scsi mid-layer won't require wholesale
1643 * changes to drivers that use this feature.
1645 void scsi_unblock_requests(struct Scsi_Host *shost)
1647 shost->host_self_blocked = 0;
1648 scsi_run_host_queues(shost);
1650 EXPORT_SYMBOL(scsi_unblock_requests);
1652 int __init scsi_init_queue(void)
1656 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1657 sizeof(struct scsi_io_context),
1659 if (!scsi_io_context_cache) {
1660 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1664 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1665 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1666 int size = sgp->size * sizeof(struct scatterlist);
1668 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1669 SLAB_HWCACHE_ALIGN, NULL);
1671 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1675 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1678 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1686 void scsi_exit_queue(void)
1690 kmem_cache_destroy(scsi_io_context_cache);
1692 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1693 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1694 mempool_destroy(sgp->pool);
1695 kmem_cache_destroy(sgp->slab);
1700 * scsi_mode_select - issue a mode select
1701 * @sdev: SCSI device to be queried
1702 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1703 * @sp: Save page bit (0 == don't save, 1 == save)
1704 * @modepage: mode page being requested
1705 * @buffer: request buffer (may not be smaller than eight bytes)
1706 * @len: length of request buffer.
1707 * @timeout: command timeout
1708 * @retries: number of retries before failing
1709 * @data: returns a structure abstracting the mode header data
1710 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1711 * must be SCSI_SENSE_BUFFERSIZE big.
1713 * Returns zero if successful; negative error number or scsi
1718 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1719 unsigned char *buffer, int len, int timeout, int retries,
1720 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1722 unsigned char cmd[10];
1723 unsigned char *real_buffer;
1726 memset(cmd, 0, sizeof(cmd));
1727 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1729 if (sdev->use_10_for_ms) {
1732 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1735 memcpy(real_buffer + 8, buffer, len);
1739 real_buffer[2] = data->medium_type;
1740 real_buffer[3] = data->device_specific;
1741 real_buffer[4] = data->longlba ? 0x01 : 0;
1743 real_buffer[6] = data->block_descriptor_length >> 8;
1744 real_buffer[7] = data->block_descriptor_length;
1746 cmd[0] = MODE_SELECT_10;
1750 if (len > 255 || data->block_descriptor_length > 255 ||
1754 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1757 memcpy(real_buffer + 4, buffer, len);
1760 real_buffer[1] = data->medium_type;
1761 real_buffer[2] = data->device_specific;
1762 real_buffer[3] = data->block_descriptor_length;
1765 cmd[0] = MODE_SELECT;
1769 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1770 sshdr, timeout, retries);
1774 EXPORT_SYMBOL_GPL(scsi_mode_select);
1777 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1778 * @sdev: SCSI device to be queried
1779 * @dbd: set if mode sense will allow block descriptors to be returned
1780 * @modepage: mode page being requested
1781 * @buffer: request buffer (may not be smaller than eight bytes)
1782 * @len: length of request buffer.
1783 * @timeout: command timeout
1784 * @retries: number of retries before failing
1785 * @data: returns a structure abstracting the mode header data
1786 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1787 * must be SCSI_SENSE_BUFFERSIZE big.
1789 * Returns zero if unsuccessful, or the header offset (either 4
1790 * or 8 depending on whether a six or ten byte command was
1791 * issued) if successful.
1794 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1795 unsigned char *buffer, int len, int timeout, int retries,
1796 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1798 unsigned char cmd[12];
1802 struct scsi_sense_hdr my_sshdr;
1804 memset(data, 0, sizeof(*data));
1805 memset(&cmd[0], 0, 12);
1806 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1809 /* caller might not be interested in sense, but we need it */
1814 use_10_for_ms = sdev->use_10_for_ms;
1816 if (use_10_for_ms) {
1820 cmd[0] = MODE_SENSE_10;
1827 cmd[0] = MODE_SENSE;
1832 memset(buffer, 0, len);
1834 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1835 sshdr, timeout, retries);
1837 /* This code looks awful: what it's doing is making sure an
1838 * ILLEGAL REQUEST sense return identifies the actual command
1839 * byte as the problem. MODE_SENSE commands can return
1840 * ILLEGAL REQUEST if the code page isn't supported */
1842 if (use_10_for_ms && !scsi_status_is_good(result) &&
1843 (driver_byte(result) & DRIVER_SENSE)) {
1844 if (scsi_sense_valid(sshdr)) {
1845 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1846 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1848 * Invalid command operation code
1850 sdev->use_10_for_ms = 0;
1856 if(scsi_status_is_good(result)) {
1857 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1858 (modepage == 6 || modepage == 8))) {
1859 /* Initio breakage? */
1862 data->medium_type = 0;
1863 data->device_specific = 0;
1865 data->block_descriptor_length = 0;
1866 } else if(use_10_for_ms) {
1867 data->length = buffer[0]*256 + buffer[1] + 2;
1868 data->medium_type = buffer[2];
1869 data->device_specific = buffer[3];
1870 data->longlba = buffer[4] & 0x01;
1871 data->block_descriptor_length = buffer[6]*256
1874 data->length = buffer[0] + 1;
1875 data->medium_type = buffer[1];
1876 data->device_specific = buffer[2];
1877 data->block_descriptor_length = buffer[3];
1879 data->header_length = header_length;
1884 EXPORT_SYMBOL(scsi_mode_sense);
1887 * scsi_test_unit_ready - test if unit is ready
1888 * @sdev: scsi device to change the state of.
1889 * @timeout: command timeout
1890 * @retries: number of retries before failing
1891 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
1892 * returning sense. Make sure that this is cleared before passing
1895 * Returns zero if unsuccessful or an error if TUR failed. For
1896 * removable media, a return of NOT_READY or UNIT_ATTENTION is
1897 * translated to success, with the ->changed flag updated.
1900 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
1901 struct scsi_sense_hdr *sshdr_external)
1904 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1906 struct scsi_sense_hdr *sshdr;
1909 if (!sshdr_external)
1910 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
1912 sshdr = sshdr_external;
1914 /* try to eat the UNIT_ATTENTION if there are enough retries */
1916 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
1918 } while ((driver_byte(result) & DRIVER_SENSE) &&
1919 sshdr && sshdr->sense_key == UNIT_ATTENTION &&
1923 /* could not allocate sense buffer, so can't process it */
1926 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
1928 if ((scsi_sense_valid(sshdr)) &&
1929 ((sshdr->sense_key == UNIT_ATTENTION) ||
1930 (sshdr->sense_key == NOT_READY))) {
1935 if (!sshdr_external)
1939 EXPORT_SYMBOL(scsi_test_unit_ready);
1942 * scsi_device_set_state - Take the given device through the device state model.
1943 * @sdev: scsi device to change the state of.
1944 * @state: state to change to.
1946 * Returns zero if unsuccessful or an error if the requested
1947 * transition is illegal.
1950 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1952 enum scsi_device_state oldstate = sdev->sdev_state;
1954 if (state == oldstate)
1959 /* There are no legal states that come back to
1960 * created. This is the manually initialised start
2034 sdev->sdev_state = state;
2038 SCSI_LOG_ERROR_RECOVERY(1,
2039 sdev_printk(KERN_ERR, sdev,
2040 "Illegal state transition %s->%s\n",
2041 scsi_device_state_name(oldstate),
2042 scsi_device_state_name(state))
2046 EXPORT_SYMBOL(scsi_device_set_state);
2049 * sdev_evt_emit - emit a single SCSI device uevent
2050 * @sdev: associated SCSI device
2051 * @evt: event to emit
2053 * Send a single uevent (scsi_event) to the associated scsi_device.
2055 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2060 switch (evt->evt_type) {
2061 case SDEV_EVT_MEDIA_CHANGE:
2062 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2072 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2076 * sdev_evt_thread - send a uevent for each scsi event
2077 * @work: work struct for scsi_device
2079 * Dispatch queued events to their associated scsi_device kobjects
2082 void scsi_evt_thread(struct work_struct *work)
2084 struct scsi_device *sdev;
2085 LIST_HEAD(event_list);
2087 sdev = container_of(work, struct scsi_device, event_work);
2090 struct scsi_event *evt;
2091 struct list_head *this, *tmp;
2092 unsigned long flags;
2094 spin_lock_irqsave(&sdev->list_lock, flags);
2095 list_splice_init(&sdev->event_list, &event_list);
2096 spin_unlock_irqrestore(&sdev->list_lock, flags);
2098 if (list_empty(&event_list))
2101 list_for_each_safe(this, tmp, &event_list) {
2102 evt = list_entry(this, struct scsi_event, node);
2103 list_del(&evt->node);
2104 scsi_evt_emit(sdev, evt);
2111 * sdev_evt_send - send asserted event to uevent thread
2112 * @sdev: scsi_device event occurred on
2113 * @evt: event to send
2115 * Assert scsi device event asynchronously.
2117 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2119 unsigned long flags;
2121 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2126 spin_lock_irqsave(&sdev->list_lock, flags);
2127 list_add_tail(&evt->node, &sdev->event_list);
2128 schedule_work(&sdev->event_work);
2129 spin_unlock_irqrestore(&sdev->list_lock, flags);
2131 EXPORT_SYMBOL_GPL(sdev_evt_send);
2134 * sdev_evt_alloc - allocate a new scsi event
2135 * @evt_type: type of event to allocate
2136 * @gfpflags: GFP flags for allocation
2138 * Allocates and returns a new scsi_event.
2140 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2143 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2147 evt->evt_type = evt_type;
2148 INIT_LIST_HEAD(&evt->node);
2150 /* evt_type-specific initialization, if any */
2152 case SDEV_EVT_MEDIA_CHANGE:
2160 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2163 * sdev_evt_send_simple - send asserted event to uevent thread
2164 * @sdev: scsi_device event occurred on
2165 * @evt_type: type of event to send
2166 * @gfpflags: GFP flags for allocation
2168 * Assert scsi device event asynchronously, given an event type.
2170 void sdev_evt_send_simple(struct scsi_device *sdev,
2171 enum scsi_device_event evt_type, gfp_t gfpflags)
2173 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2175 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2180 sdev_evt_send(sdev, evt);
2182 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2185 * scsi_device_quiesce - Block user issued commands.
2186 * @sdev: scsi device to quiesce.
2188 * This works by trying to transition to the SDEV_QUIESCE state
2189 * (which must be a legal transition). When the device is in this
2190 * state, only special requests will be accepted, all others will
2191 * be deferred. Since special requests may also be requeued requests,
2192 * a successful return doesn't guarantee the device will be
2193 * totally quiescent.
2195 * Must be called with user context, may sleep.
2197 * Returns zero if unsuccessful or an error if not.
2200 scsi_device_quiesce(struct scsi_device *sdev)
2202 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2206 scsi_run_queue(sdev->request_queue);
2207 while (sdev->device_busy) {
2208 msleep_interruptible(200);
2209 scsi_run_queue(sdev->request_queue);
2213 EXPORT_SYMBOL(scsi_device_quiesce);
2216 * scsi_device_resume - Restart user issued commands to a quiesced device.
2217 * @sdev: scsi device to resume.
2219 * Moves the device from quiesced back to running and restarts the
2222 * Must be called with user context, may sleep.
2225 scsi_device_resume(struct scsi_device *sdev)
2227 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2229 scsi_run_queue(sdev->request_queue);
2231 EXPORT_SYMBOL(scsi_device_resume);
2234 device_quiesce_fn(struct scsi_device *sdev, void *data)
2236 scsi_device_quiesce(sdev);
2240 scsi_target_quiesce(struct scsi_target *starget)
2242 starget_for_each_device(starget, NULL, device_quiesce_fn);
2244 EXPORT_SYMBOL(scsi_target_quiesce);
2247 device_resume_fn(struct scsi_device *sdev, void *data)
2249 scsi_device_resume(sdev);
2253 scsi_target_resume(struct scsi_target *starget)
2255 starget_for_each_device(starget, NULL, device_resume_fn);
2257 EXPORT_SYMBOL(scsi_target_resume);
2260 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2261 * @sdev: device to block
2263 * Block request made by scsi lld's to temporarily stop all
2264 * scsi commands on the specified device. Called from interrupt
2265 * or normal process context.
2267 * Returns zero if successful or error if not
2270 * This routine transitions the device to the SDEV_BLOCK state
2271 * (which must be a legal transition). When the device is in this
2272 * state, all commands are deferred until the scsi lld reenables
2273 * the device with scsi_device_unblock or device_block_tmo fires.
2274 * This routine assumes the host_lock is held on entry.
2277 scsi_internal_device_block(struct scsi_device *sdev)
2279 struct request_queue *q = sdev->request_queue;
2280 unsigned long flags;
2283 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2288 * The device has transitioned to SDEV_BLOCK. Stop the
2289 * block layer from calling the midlayer with this device's
2292 spin_lock_irqsave(q->queue_lock, flags);
2294 spin_unlock_irqrestore(q->queue_lock, flags);
2298 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2301 * scsi_internal_device_unblock - resume a device after a block request
2302 * @sdev: device to resume
2304 * Called by scsi lld's or the midlayer to restart the device queue
2305 * for the previously suspended scsi device. Called from interrupt or
2306 * normal process context.
2308 * Returns zero if successful or error if not.
2311 * This routine transitions the device to the SDEV_RUNNING state
2312 * (which must be a legal transition) allowing the midlayer to
2313 * goose the queue for this device. This routine assumes the
2314 * host_lock is held upon entry.
2317 scsi_internal_device_unblock(struct scsi_device *sdev)
2319 struct request_queue *q = sdev->request_queue;
2321 unsigned long flags;
2324 * Try to transition the scsi device to SDEV_RUNNING
2325 * and goose the device queue if successful.
2327 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2331 spin_lock_irqsave(q->queue_lock, flags);
2333 spin_unlock_irqrestore(q->queue_lock, flags);
2337 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2340 device_block(struct scsi_device *sdev, void *data)
2342 scsi_internal_device_block(sdev);
2346 target_block(struct device *dev, void *data)
2348 if (scsi_is_target_device(dev))
2349 starget_for_each_device(to_scsi_target(dev), NULL,
2355 scsi_target_block(struct device *dev)
2357 if (scsi_is_target_device(dev))
2358 starget_for_each_device(to_scsi_target(dev), NULL,
2361 device_for_each_child(dev, NULL, target_block);
2363 EXPORT_SYMBOL_GPL(scsi_target_block);
2366 device_unblock(struct scsi_device *sdev, void *data)
2368 scsi_internal_device_unblock(sdev);
2372 target_unblock(struct device *dev, void *data)
2374 if (scsi_is_target_device(dev))
2375 starget_for_each_device(to_scsi_target(dev), NULL,
2381 scsi_target_unblock(struct device *dev)
2383 if (scsi_is_target_device(dev))
2384 starget_for_each_device(to_scsi_target(dev), NULL,
2387 device_for_each_child(dev, NULL, target_unblock);
2389 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2392 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2393 * @sgl: scatter-gather list
2394 * @sg_count: number of segments in sg
2395 * @offset: offset in bytes into sg, on return offset into the mapped area
2396 * @len: bytes to map, on return number of bytes mapped
2398 * Returns virtual address of the start of the mapped page
2400 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2401 size_t *offset, size_t *len)
2404 size_t sg_len = 0, len_complete = 0;
2405 struct scatterlist *sg;
2408 WARN_ON(!irqs_disabled());
2410 for_each_sg(sgl, sg, sg_count, i) {
2411 len_complete = sg_len; /* Complete sg-entries */
2412 sg_len += sg->length;
2413 if (sg_len > *offset)
2417 if (unlikely(i == sg_count)) {
2418 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2420 __FUNCTION__, sg_len, *offset, sg_count);
2425 /* Offset starting from the beginning of first page in this sg-entry */
2426 *offset = *offset - len_complete + sg->offset;
2428 /* Assumption: contiguous pages can be accessed as "page + i" */
2429 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2430 *offset &= ~PAGE_MASK;
2432 /* Bytes in this sg-entry from *offset to the end of the page */
2433 sg_len = PAGE_SIZE - *offset;
2437 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2439 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2442 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2443 * @virt: virtual address to be unmapped
2445 void scsi_kunmap_atomic_sg(void *virt)
2447 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2449 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);