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/bitops.h>
12 #include <linux/blkdev.h>
13 #include <linux/completion.h>
14 #include <linux/kernel.h>
15 #include <linux/mempool.h>
16 #include <linux/slab.h>
17 #include <linux/init.h>
18 #include <linux/pci.h>
19 #include <linux/delay.h>
20 #include <linux/hardirq.h>
21 #include <linux/scatterlist.h>
23 #include <scsi/scsi.h>
24 #include <scsi/scsi_cmnd.h>
25 #include <scsi/scsi_dbg.h>
26 #include <scsi/scsi_device.h>
27 #include <scsi/scsi_driver.h>
28 #include <scsi/scsi_eh.h>
29 #include <scsi/scsi_host.h>
31 #include "scsi_priv.h"
32 #include "scsi_logging.h"
35 #define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
36 #define SG_MEMPOOL_SIZE 2
38 struct scsi_host_sg_pool {
41 struct kmem_cache *slab;
45 #define SP(x) { x, "sgpool-" __stringify(x) }
46 #if (SCSI_MAX_SG_SEGMENTS < 32)
47 #error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
49 static struct scsi_host_sg_pool scsi_sg_pools[] = {
52 #if (SCSI_MAX_SG_SEGMENTS > 32)
54 #if (SCSI_MAX_SG_SEGMENTS > 64)
56 #if (SCSI_MAX_SG_SEGMENTS > 128)
58 #if (SCSI_MAX_SG_SEGMENTS > 256)
59 #error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
64 SP(SCSI_MAX_SG_SEGMENTS)
68 static struct kmem_cache *scsi_bidi_sdb_cache;
70 static void scsi_run_queue(struct request_queue *q);
73 * Function: scsi_unprep_request()
75 * Purpose: Remove all preparation done for a request, including its
76 * associated scsi_cmnd, so that it can be requeued.
78 * Arguments: req - request to unprepare
80 * Lock status: Assumed that no locks are held upon entry.
84 static void scsi_unprep_request(struct request *req)
86 struct scsi_cmnd *cmd = req->special;
88 req->cmd_flags &= ~REQ_DONTPREP;
91 scsi_put_command(cmd);
95 * Function: scsi_queue_insert()
97 * Purpose: Insert a command in the midlevel queue.
99 * Arguments: cmd - command that we are adding to queue.
100 * reason - why we are inserting command to queue.
102 * Lock status: Assumed that lock is not held upon entry.
106 * Notes: We do this for one of two cases. Either the host is busy
107 * and it cannot accept any more commands for the time being,
108 * or the device returned QUEUE_FULL and can accept no more
110 * Notes: This could be called either from an interrupt context or a
111 * normal process context.
113 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
115 struct Scsi_Host *host = cmd->device->host;
116 struct scsi_device *device = cmd->device;
117 struct request_queue *q = device->request_queue;
121 printk("Inserting command %p into mlqueue\n", cmd));
124 * Set the appropriate busy bit for the device/host.
126 * If the host/device isn't busy, assume that something actually
127 * completed, and that we should be able to queue a command now.
129 * Note that the prior mid-layer assumption that any host could
130 * always queue at least one command is now broken. The mid-layer
131 * will implement a user specifiable stall (see
132 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
133 * if a command is requeued with no other commands outstanding
134 * either for the device or for the host.
136 if (reason == SCSI_MLQUEUE_HOST_BUSY)
137 host->host_blocked = host->max_host_blocked;
138 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
139 device->device_blocked = device->max_device_blocked;
142 * Decrement the counters, since these commands are no longer
143 * active on the host/device.
145 scsi_device_unbusy(device);
148 * Requeue this command. It will go before all other commands
149 * that are already in the queue.
151 * NOTE: there is magic here about the way the queue is plugged if
152 * we have no outstanding commands.
154 * Although we *don't* plug the queue, we call the request
155 * function. The SCSI request function detects the blocked condition
156 * and plugs the queue appropriately.
158 spin_lock_irqsave(q->queue_lock, flags);
159 blk_requeue_request(q, cmd->request);
160 spin_unlock_irqrestore(q->queue_lock, flags);
168 * scsi_execute - insert request and wait for the result
171 * @data_direction: data direction
172 * @buffer: data buffer
173 * @bufflen: len of buffer
174 * @sense: optional sense buffer
175 * @timeout: request timeout in seconds
176 * @retries: number of times to retry request
177 * @flags: or into request flags;
179 * returns the req->errors value which is the scsi_cmnd result
182 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
183 int data_direction, void *buffer, unsigned bufflen,
184 unsigned char *sense, int timeout, int retries, int flags)
187 int write = (data_direction == DMA_TO_DEVICE);
188 int ret = DRIVER_ERROR << 24;
190 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
192 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
193 buffer, bufflen, __GFP_WAIT))
196 req->cmd_len = COMMAND_SIZE(cmd[0]);
197 memcpy(req->cmd, cmd, req->cmd_len);
200 req->retries = retries;
201 req->timeout = timeout;
202 req->cmd_type = REQ_TYPE_BLOCK_PC;
203 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
206 * head injection *required* here otherwise quiesce won't work
208 blk_execute_rq(req->q, NULL, req, 1);
212 blk_put_request(req);
216 EXPORT_SYMBOL(scsi_execute);
219 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
220 int data_direction, void *buffer, unsigned bufflen,
221 struct scsi_sense_hdr *sshdr, int timeout, int retries)
227 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
229 return DRIVER_ERROR << 24;
231 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
232 sense, timeout, retries, 0);
234 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
239 EXPORT_SYMBOL(scsi_execute_req);
241 struct scsi_io_context {
243 void (*done)(void *data, char *sense, int result, int resid);
244 char sense[SCSI_SENSE_BUFFERSIZE];
247 static struct kmem_cache *scsi_io_context_cache;
249 static void scsi_end_async(struct request *req, int uptodate)
251 struct scsi_io_context *sioc = req->end_io_data;
254 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
256 kmem_cache_free(scsi_io_context_cache, sioc);
257 __blk_put_request(req->q, req);
260 static int scsi_merge_bio(struct request *rq, struct bio *bio)
262 struct request_queue *q = rq->q;
264 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
265 if (rq_data_dir(rq) == WRITE)
266 bio->bi_rw |= (1 << BIO_RW);
267 blk_queue_bounce(q, &bio);
269 return blk_rq_append_bio(q, rq, bio);
272 static void scsi_bi_endio(struct bio *bio, int error)
278 * scsi_req_map_sg - map a scatterlist into a request
279 * @rq: request to fill
281 * @nsegs: number of elements
282 * @bufflen: len of buffer
283 * @gfp: memory allocation flags
285 * scsi_req_map_sg maps a scatterlist into a request so that the
286 * request can be sent to the block layer. We do not trust the scatterlist
287 * sent to use, as some ULDs use that struct to only organize the pages.
289 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
290 int nsegs, unsigned bufflen, gfp_t gfp)
292 struct request_queue *q = rq->q;
293 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
294 unsigned int data_len = bufflen, len, bytes, off;
295 struct scatterlist *sg;
297 struct bio *bio = NULL;
298 int i, err, nr_vecs = 0;
300 for_each_sg(sgl, sg, nsegs, i) {
306 while (len > 0 && data_len > 0) {
308 * sg sends a scatterlist that is larger than
309 * the data_len it wants transferred for certain
312 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
313 bytes = min(bytes, data_len);
316 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
319 bio = bio_alloc(gfp, nr_vecs);
324 bio->bi_end_io = scsi_bi_endio;
327 if (bio_add_pc_page(q, bio, page, bytes, off) !=
334 if (bio->bi_vcnt >= nr_vecs) {
335 err = scsi_merge_bio(rq, bio);
350 rq->buffer = rq->data = NULL;
351 rq->data_len = bufflen;
355 while ((bio = rq->bio) != NULL) {
356 rq->bio = bio->bi_next;
358 * call endio instead of bio_put incase it was bounced
367 * scsi_execute_async - insert request
370 * @cmd_len: length of scsi cdb
371 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
372 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
373 * @bufflen: len of buffer
374 * @use_sg: if buffer is a scatterlist this is the number of elements
375 * @timeout: request timeout in seconds
376 * @retries: number of times to retry request
377 * @privdata: data passed to done()
378 * @done: callback function when done
379 * @gfp: memory allocation flags
381 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
382 int cmd_len, int data_direction, void *buffer, unsigned bufflen,
383 int use_sg, int timeout, int retries, void *privdata,
384 void (*done)(void *, char *, int, int), gfp_t gfp)
387 struct scsi_io_context *sioc;
389 int write = (data_direction == DMA_TO_DEVICE);
391 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
393 return DRIVER_ERROR << 24;
395 req = blk_get_request(sdev->request_queue, write, gfp);
398 req->cmd_type = REQ_TYPE_BLOCK_PC;
399 req->cmd_flags |= REQ_QUIET;
402 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
404 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
409 req->cmd_len = cmd_len;
410 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
411 memcpy(req->cmd, cmd, req->cmd_len);
412 req->sense = sioc->sense;
414 req->timeout = timeout;
415 req->retries = retries;
416 req->end_io_data = sioc;
418 sioc->data = privdata;
421 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
425 blk_put_request(req);
427 kmem_cache_free(scsi_io_context_cache, sioc);
428 return DRIVER_ERROR << 24;
430 EXPORT_SYMBOL_GPL(scsi_execute_async);
433 * Function: scsi_init_cmd_errh()
435 * Purpose: Initialize cmd fields related to error handling.
437 * Arguments: cmd - command that is ready to be queued.
439 * Notes: This function has the job of initializing a number of
440 * fields related to error handling. Typically this will
441 * be called once for each command, as required.
443 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
445 cmd->serial_number = 0;
446 scsi_set_resid(cmd, 0);
447 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
448 if (cmd->cmd_len == 0)
449 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
452 void scsi_device_unbusy(struct scsi_device *sdev)
454 struct Scsi_Host *shost = sdev->host;
457 spin_lock_irqsave(shost->host_lock, flags);
459 if (unlikely(scsi_host_in_recovery(shost) &&
460 (shost->host_failed || shost->host_eh_scheduled)))
461 scsi_eh_wakeup(shost);
462 spin_unlock(shost->host_lock);
463 spin_lock(sdev->request_queue->queue_lock);
465 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
469 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
470 * and call blk_run_queue for all the scsi_devices on the target -
471 * including current_sdev first.
473 * Called with *no* scsi locks held.
475 static void scsi_single_lun_run(struct scsi_device *current_sdev)
477 struct Scsi_Host *shost = current_sdev->host;
478 struct scsi_device *sdev, *tmp;
479 struct scsi_target *starget = scsi_target(current_sdev);
482 spin_lock_irqsave(shost->host_lock, flags);
483 starget->starget_sdev_user = NULL;
484 spin_unlock_irqrestore(shost->host_lock, flags);
487 * Call blk_run_queue for all LUNs on the target, starting with
488 * current_sdev. We race with others (to set starget_sdev_user),
489 * but in most cases, we will be first. Ideally, each LU on the
490 * target would get some limited time or requests on the target.
492 blk_run_queue(current_sdev->request_queue);
494 spin_lock_irqsave(shost->host_lock, flags);
495 if (starget->starget_sdev_user)
497 list_for_each_entry_safe(sdev, tmp, &starget->devices,
498 same_target_siblings) {
499 if (sdev == current_sdev)
501 if (scsi_device_get(sdev))
504 spin_unlock_irqrestore(shost->host_lock, flags);
505 blk_run_queue(sdev->request_queue);
506 spin_lock_irqsave(shost->host_lock, flags);
508 scsi_device_put(sdev);
511 spin_unlock_irqrestore(shost->host_lock, flags);
515 * Function: scsi_run_queue()
517 * Purpose: Select a proper request queue to serve next
519 * Arguments: q - last request's queue
523 * Notes: The previous command was completely finished, start
524 * a new one if possible.
526 static void scsi_run_queue(struct request_queue *q)
528 struct scsi_device *sdev = q->queuedata;
529 struct Scsi_Host *shost = sdev->host;
532 if (scsi_target(sdev)->single_lun)
533 scsi_single_lun_run(sdev);
535 spin_lock_irqsave(shost->host_lock, flags);
536 while (!list_empty(&shost->starved_list) &&
537 !shost->host_blocked && !shost->host_self_blocked &&
538 !((shost->can_queue > 0) &&
539 (shost->host_busy >= shost->can_queue))) {
541 * As long as shost is accepting commands and we have
542 * starved queues, call blk_run_queue. scsi_request_fn
543 * drops the queue_lock and can add us back to the
546 * host_lock protects the starved_list and starved_entry.
547 * scsi_request_fn must get the host_lock before checking
548 * or modifying starved_list or starved_entry.
550 sdev = list_entry(shost->starved_list.next,
551 struct scsi_device, starved_entry);
552 list_del_init(&sdev->starved_entry);
553 spin_unlock_irqrestore(shost->host_lock, flags);
556 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
557 !test_and_set_bit(QUEUE_FLAG_REENTER,
558 &sdev->request_queue->queue_flags)) {
559 blk_run_queue(sdev->request_queue);
560 clear_bit(QUEUE_FLAG_REENTER,
561 &sdev->request_queue->queue_flags);
563 blk_run_queue(sdev->request_queue);
565 spin_lock_irqsave(shost->host_lock, flags);
566 if (unlikely(!list_empty(&sdev->starved_entry)))
568 * sdev lost a race, and was put back on the
569 * starved list. This is unlikely but without this
570 * in theory we could loop forever.
574 spin_unlock_irqrestore(shost->host_lock, flags);
580 * Function: scsi_requeue_command()
582 * Purpose: Handle post-processing of completed commands.
584 * Arguments: q - queue to operate on
585 * cmd - command that may need to be requeued.
589 * Notes: After command completion, there may be blocks left
590 * over which weren't finished by the previous command
591 * this can be for a number of reasons - the main one is
592 * I/O errors in the middle of the request, in which case
593 * we need to request the blocks that come after the bad
595 * Notes: Upon return, cmd is a stale pointer.
597 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
599 struct request *req = cmd->request;
602 scsi_unprep_request(req);
603 spin_lock_irqsave(q->queue_lock, flags);
604 blk_requeue_request(q, req);
605 spin_unlock_irqrestore(q->queue_lock, flags);
610 void scsi_next_command(struct scsi_cmnd *cmd)
612 struct scsi_device *sdev = cmd->device;
613 struct request_queue *q = sdev->request_queue;
615 /* need to hold a reference on the device before we let go of the cmd */
616 get_device(&sdev->sdev_gendev);
618 scsi_put_command(cmd);
621 /* ok to remove device now */
622 put_device(&sdev->sdev_gendev);
625 void scsi_run_host_queues(struct Scsi_Host *shost)
627 struct scsi_device *sdev;
629 shost_for_each_device(sdev, shost)
630 scsi_run_queue(sdev->request_queue);
634 * Function: scsi_end_request()
636 * Purpose: Post-processing of completed commands (usually invoked at end
637 * of upper level post-processing and scsi_io_completion).
639 * Arguments: cmd - command that is complete.
640 * error - 0 if I/O indicates success, < 0 for I/O error.
641 * bytes - number of bytes of completed I/O
642 * requeue - indicates whether we should requeue leftovers.
644 * Lock status: Assumed that lock is not held upon entry.
646 * Returns: cmd if requeue required, NULL otherwise.
648 * Notes: This is called for block device requests in order to
649 * mark some number of sectors as complete.
651 * We are guaranteeing that the request queue will be goosed
652 * at some point during this call.
653 * Notes: If cmd was requeued, upon return it will be a stale pointer.
655 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
656 int bytes, int requeue)
658 struct request_queue *q = cmd->device->request_queue;
659 struct request *req = cmd->request;
662 * If there are blocks left over at the end, set up the command
663 * to queue the remainder of them.
665 if (blk_end_request(req, error, bytes)) {
666 int leftover = (req->hard_nr_sectors << 9);
668 if (blk_pc_request(req))
669 leftover = req->data_len;
671 /* kill remainder if no retrys */
672 if (error && blk_noretry_request(req))
673 blk_end_request(req, error, leftover);
677 * Bleah. Leftovers again. Stick the
678 * leftovers in the front of the
679 * queue, and goose the queue again.
681 scsi_requeue_command(q, cmd);
689 * This will goose the queue request function at the end, so we don't
690 * need to worry about launching another command.
692 scsi_next_command(cmd);
696 static inline unsigned int scsi_sgtable_index(unsigned short nents)
700 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
705 index = get_count_order(nents) - 3;
710 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
712 struct scsi_host_sg_pool *sgp;
714 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
715 mempool_free(sgl, sgp->pool);
718 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
720 struct scsi_host_sg_pool *sgp;
722 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
723 return mempool_alloc(sgp->pool, gfp_mask);
726 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
733 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
734 gfp_mask, scsi_sg_alloc);
736 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
742 static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
744 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
748 * Function: scsi_release_buffers()
750 * Purpose: Completion processing for block device I/O requests.
752 * Arguments: cmd - command that we are bailing.
754 * Lock status: Assumed that no lock is held upon entry.
758 * Notes: In the event that an upper level driver rejects a
759 * command, we must release resources allocated during
760 * the __init_io() function. Primarily this would involve
761 * the scatter-gather table, and potentially any bounce
764 void scsi_release_buffers(struct scsi_cmnd *cmd)
766 if (cmd->sdb.table.nents)
767 scsi_free_sgtable(&cmd->sdb);
769 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
771 if (scsi_bidi_cmnd(cmd)) {
772 struct scsi_data_buffer *bidi_sdb =
773 cmd->request->next_rq->special;
774 scsi_free_sgtable(bidi_sdb);
775 kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb);
776 cmd->request->next_rq->special = NULL;
779 EXPORT_SYMBOL(scsi_release_buffers);
782 * Bidi commands Must be complete as a whole, both sides at once.
783 * If part of the bytes were written and lld returned
784 * scsi_in()->resid and/or scsi_out()->resid this information will be left
785 * in req->data_len and req->next_rq->data_len. The upper-layer driver can
786 * decide what to do with this information.
788 void scsi_end_bidi_request(struct scsi_cmnd *cmd)
790 struct request *req = cmd->request;
791 unsigned int dlen = req->data_len;
792 unsigned int next_dlen = req->next_rq->data_len;
794 req->data_len = scsi_out(cmd)->resid;
795 req->next_rq->data_len = scsi_in(cmd)->resid;
797 /* The req and req->next_rq have not been completed */
798 BUG_ON(blk_end_bidi_request(req, 0, dlen, next_dlen));
800 scsi_release_buffers(cmd);
803 * This will goose the queue request function at the end, so we don't
804 * need to worry about launching another command.
806 scsi_next_command(cmd);
810 * Function: scsi_io_completion()
812 * Purpose: Completion processing for block device I/O requests.
814 * Arguments: cmd - command that is finished.
816 * Lock status: Assumed that no lock is held upon entry.
820 * Notes: This function is matched in terms of capabilities to
821 * the function that created the scatter-gather list.
822 * In other words, if there are no bounce buffers
823 * (the normal case for most drivers), we don't need
824 * the logic to deal with cleaning up afterwards.
826 * We must do one of several things here:
828 * a) Call scsi_end_request. This will finish off the
829 * specified number of sectors. If we are done, the
830 * command block will be released, and the queue
831 * function will be goosed. If we are not done, then
832 * scsi_end_request will directly goose the queue.
834 * b) We can just use scsi_requeue_command() here. This would
835 * be used if we just wanted to retry, for example.
837 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
839 int result = cmd->result;
840 int this_count = scsi_bufflen(cmd);
841 struct request_queue *q = cmd->device->request_queue;
842 struct request *req = cmd->request;
843 int clear_errors = 1;
844 struct scsi_sense_hdr sshdr;
846 int sense_deferred = 0;
849 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
851 sense_deferred = scsi_sense_is_deferred(&sshdr);
854 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
855 req->errors = result;
858 if (sense_valid && req->sense) {
860 * SG_IO wants current and deferred errors
862 int len = 8 + cmd->sense_buffer[7];
864 if (len > SCSI_SENSE_BUFFERSIZE)
865 len = SCSI_SENSE_BUFFERSIZE;
866 memcpy(req->sense, cmd->sense_buffer, len);
867 req->sense_len = len;
870 if (scsi_bidi_cmnd(cmd)) {
871 /* will also release_buffers */
872 scsi_end_bidi_request(cmd);
875 req->data_len = scsi_get_resid(cmd);
878 BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */
879 scsi_release_buffers(cmd);
882 * Next deal with any sectors which we were able to correctly
885 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
887 req->nr_sectors, good_bytes));
892 /* A number of bytes were successfully read. If there
893 * are leftovers and there is some kind of error
894 * (result != 0), retry the rest.
896 if (scsi_end_request(cmd, 0, good_bytes, result == 0) == NULL)
899 /* good_bytes = 0, or (inclusive) there were leftovers and
900 * result = 0, so scsi_end_request couldn't retry.
902 if (sense_valid && !sense_deferred) {
903 switch (sshdr.sense_key) {
905 if (cmd->device->removable) {
906 /* Detected disc change. Set a bit
907 * and quietly refuse further access.
909 cmd->device->changed = 1;
910 scsi_end_request(cmd, -EIO, this_count, 1);
913 /* Must have been a power glitch, or a
914 * bus reset. Could not have been a
915 * media change, so we just retry the
916 * request and see what happens.
918 scsi_requeue_command(q, cmd);
922 case ILLEGAL_REQUEST:
923 /* If we had an ILLEGAL REQUEST returned, then
924 * we may have performed an unsupported
925 * command. The only thing this should be
926 * would be a ten byte read where only a six
927 * byte read was supported. Also, on a system
928 * where READ CAPACITY failed, we may have
929 * read past the end of the disk.
931 if ((cmd->device->use_10_for_rw &&
932 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
933 (cmd->cmnd[0] == READ_10 ||
934 cmd->cmnd[0] == WRITE_10)) {
935 cmd->device->use_10_for_rw = 0;
936 /* This will cause a retry with a
939 scsi_requeue_command(q, cmd);
942 scsi_end_request(cmd, -EIO, this_count, 1);
947 /* If the device is in the process of becoming
948 * ready, or has a temporary blockage, retry.
950 if (sshdr.asc == 0x04) {
951 switch (sshdr.ascq) {
952 case 0x01: /* becoming ready */
953 case 0x04: /* format in progress */
954 case 0x05: /* rebuild in progress */
955 case 0x06: /* recalculation in progress */
956 case 0x07: /* operation in progress */
957 case 0x08: /* Long write in progress */
958 case 0x09: /* self test in progress */
959 scsi_requeue_command(q, cmd);
965 if (!(req->cmd_flags & REQ_QUIET))
966 scsi_cmd_print_sense_hdr(cmd,
970 scsi_end_request(cmd, -EIO, this_count, 1);
972 case VOLUME_OVERFLOW:
973 if (!(req->cmd_flags & REQ_QUIET)) {
974 scmd_printk(KERN_INFO, cmd,
975 "Volume overflow, CDB: ");
976 __scsi_print_command(cmd->cmnd);
977 scsi_print_sense("", cmd);
979 /* See SSC3rXX or current. */
980 scsi_end_request(cmd, -EIO, this_count, 1);
986 if (host_byte(result) == DID_RESET) {
987 /* Third party bus reset or reset for error recovery
988 * reasons. Just retry the request and see what
991 scsi_requeue_command(q, cmd);
995 if (!(req->cmd_flags & REQ_QUIET)) {
996 scsi_print_result(cmd);
997 if (driver_byte(result) & DRIVER_SENSE)
998 scsi_print_sense("", cmd);
1001 scsi_end_request(cmd, -EIO, this_count, !result);
1004 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
1010 * If sg table allocation fails, requeue request later.
1012 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
1014 return BLKPREP_DEFER;
1018 if (blk_pc_request(req))
1019 sdb->length = req->data_len;
1021 sdb->length = req->nr_sectors << 9;
1024 * Next, walk the list, and fill in the addresses and sizes of
1027 count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1028 BUG_ON(count > sdb->table.nents);
1029 sdb->table.nents = count;
1034 * Function: scsi_init_io()
1036 * Purpose: SCSI I/O initialize function.
1038 * Arguments: cmd - Command descriptor we wish to initialize
1040 * Returns: 0 on success
1041 * BLKPREP_DEFER if the failure is retryable
1042 * BLKPREP_KILL if the failure is fatal
1044 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1046 int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
1050 if (blk_bidi_rq(cmd->request)) {
1051 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1052 scsi_bidi_sdb_cache, GFP_ATOMIC);
1054 error = BLKPREP_DEFER;
1058 cmd->request->next_rq->special = bidi_sdb;
1059 error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
1068 scsi_release_buffers(cmd);
1069 if (error == BLKPREP_KILL)
1070 scsi_put_command(cmd);
1071 else /* BLKPREP_DEFER */
1072 scsi_unprep_request(cmd->request);
1076 EXPORT_SYMBOL(scsi_init_io);
1078 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1079 struct request *req)
1081 struct scsi_cmnd *cmd;
1083 if (!req->special) {
1084 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1092 /* pull a tag out of the request if we have one */
1093 cmd->tag = req->tag;
1099 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1101 struct scsi_cmnd *cmd;
1102 int ret = scsi_prep_state_check(sdev, req);
1104 if (ret != BLKPREP_OK)
1107 cmd = scsi_get_cmd_from_req(sdev, req);
1109 return BLKPREP_DEFER;
1112 * BLOCK_PC requests may transfer data, in which case they must
1113 * a bio attached to them. Or they might contain a SCSI command
1114 * that does not transfer data, in which case they may optionally
1115 * submit a request without an attached bio.
1120 BUG_ON(!req->nr_phys_segments);
1122 ret = scsi_init_io(cmd, GFP_ATOMIC);
1126 BUG_ON(req->data_len);
1129 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1133 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
1134 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1135 cmd->cmd_len = req->cmd_len;
1137 cmd->sc_data_direction = DMA_NONE;
1138 else if (rq_data_dir(req) == WRITE)
1139 cmd->sc_data_direction = DMA_TO_DEVICE;
1141 cmd->sc_data_direction = DMA_FROM_DEVICE;
1143 cmd->transfersize = req->data_len;
1144 cmd->allowed = req->retries;
1145 cmd->timeout_per_command = req->timeout;
1148 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1151 * Setup a REQ_TYPE_FS command. These are simple read/write request
1152 * from filesystems that still need to be translated to SCSI CDBs from
1155 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1157 struct scsi_cmnd *cmd;
1158 int ret = scsi_prep_state_check(sdev, req);
1160 if (ret != BLKPREP_OK)
1163 * Filesystem requests must transfer data.
1165 BUG_ON(!req->nr_phys_segments);
1167 cmd = scsi_get_cmd_from_req(sdev, req);
1169 return BLKPREP_DEFER;
1171 return scsi_init_io(cmd, GFP_ATOMIC);
1173 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1175 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1177 int ret = BLKPREP_OK;
1180 * If the device is not in running state we will reject some
1183 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1184 switch (sdev->sdev_state) {
1187 * If the device is offline we refuse to process any
1188 * commands. The device must be brought online
1189 * before trying any recovery commands.
1191 sdev_printk(KERN_ERR, sdev,
1192 "rejecting I/O to offline device\n");
1197 * If the device is fully deleted, we refuse to
1198 * process any commands as well.
1200 sdev_printk(KERN_ERR, sdev,
1201 "rejecting I/O to dead device\n");
1207 * If the devices is blocked we defer normal commands.
1209 if (!(req->cmd_flags & REQ_PREEMPT))
1210 ret = BLKPREP_DEFER;
1214 * For any other not fully online state we only allow
1215 * special commands. In particular any user initiated
1216 * command is not allowed.
1218 if (!(req->cmd_flags & REQ_PREEMPT))
1225 EXPORT_SYMBOL(scsi_prep_state_check);
1227 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1229 struct scsi_device *sdev = q->queuedata;
1233 req->errors = DID_NO_CONNECT << 16;
1234 /* release the command and kill it */
1236 struct scsi_cmnd *cmd = req->special;
1237 scsi_release_buffers(cmd);
1238 scsi_put_command(cmd);
1239 req->special = NULL;
1244 * If we defer, the elv_next_request() returns NULL, but the
1245 * queue must be restarted, so we plug here if no returning
1246 * command will automatically do that.
1248 if (sdev->device_busy == 0)
1252 req->cmd_flags |= REQ_DONTPREP;
1257 EXPORT_SYMBOL(scsi_prep_return);
1259 int scsi_prep_fn(struct request_queue *q, struct request *req)
1261 struct scsi_device *sdev = q->queuedata;
1262 int ret = BLKPREP_KILL;
1264 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1265 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1266 return scsi_prep_return(q, req, ret);
1270 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1273 * Called with the queue_lock held.
1275 static inline int scsi_dev_queue_ready(struct request_queue *q,
1276 struct scsi_device *sdev)
1278 if (sdev->device_busy >= sdev->queue_depth)
1280 if (sdev->device_busy == 0 && sdev->device_blocked) {
1282 * unblock after device_blocked iterates to zero
1284 if (--sdev->device_blocked == 0) {
1286 sdev_printk(KERN_INFO, sdev,
1287 "unblocking device at zero depth\n"));
1293 if (sdev->device_blocked)
1300 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1301 * return 0. We must end up running the queue again whenever 0 is
1302 * returned, else IO can hang.
1304 * Called with host_lock held.
1306 static inline int scsi_host_queue_ready(struct request_queue *q,
1307 struct Scsi_Host *shost,
1308 struct scsi_device *sdev)
1310 if (scsi_host_in_recovery(shost))
1312 if (shost->host_busy == 0 && shost->host_blocked) {
1314 * unblock after host_blocked iterates to zero
1316 if (--shost->host_blocked == 0) {
1318 printk("scsi%d unblocking host at zero depth\n",
1325 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1326 shost->host_blocked || shost->host_self_blocked) {
1327 if (list_empty(&sdev->starved_entry))
1328 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1332 /* We're OK to process the command, so we can't be starved */
1333 if (!list_empty(&sdev->starved_entry))
1334 list_del_init(&sdev->starved_entry);
1340 * Kill a request for a dead device
1342 static void scsi_kill_request(struct request *req, struct request_queue *q)
1344 struct scsi_cmnd *cmd = req->special;
1345 struct scsi_device *sdev = cmd->device;
1346 struct Scsi_Host *shost = sdev->host;
1348 blkdev_dequeue_request(req);
1350 if (unlikely(cmd == NULL)) {
1351 printk(KERN_CRIT "impossible request in %s.\n",
1356 scsi_init_cmd_errh(cmd);
1357 cmd->result = DID_NO_CONNECT << 16;
1358 atomic_inc(&cmd->device->iorequest_cnt);
1361 * SCSI request completion path will do scsi_device_unbusy(),
1362 * bump busy counts. To bump the counters, we need to dance
1363 * with the locks as normal issue path does.
1365 sdev->device_busy++;
1366 spin_unlock(sdev->request_queue->queue_lock);
1367 spin_lock(shost->host_lock);
1369 spin_unlock(shost->host_lock);
1370 spin_lock(sdev->request_queue->queue_lock);
1375 static void scsi_softirq_done(struct request *rq)
1377 struct scsi_cmnd *cmd = rq->completion_data;
1378 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
1381 INIT_LIST_HEAD(&cmd->eh_entry);
1383 disposition = scsi_decide_disposition(cmd);
1384 if (disposition != SUCCESS &&
1385 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1386 sdev_printk(KERN_ERR, cmd->device,
1387 "timing out command, waited %lus\n",
1389 disposition = SUCCESS;
1392 scsi_log_completion(cmd, disposition);
1394 switch (disposition) {
1396 scsi_finish_command(cmd);
1399 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1401 case ADD_TO_MLQUEUE:
1402 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1405 if (!scsi_eh_scmd_add(cmd, 0))
1406 scsi_finish_command(cmd);
1411 * Function: scsi_request_fn()
1413 * Purpose: Main strategy routine for SCSI.
1415 * Arguments: q - Pointer to actual queue.
1419 * Lock status: IO request lock assumed to be held when called.
1421 static void scsi_request_fn(struct request_queue *q)
1423 struct scsi_device *sdev = q->queuedata;
1424 struct Scsi_Host *shost;
1425 struct scsi_cmnd *cmd;
1426 struct request *req;
1429 printk("scsi: killing requests for dead queue\n");
1430 while ((req = elv_next_request(q)) != NULL)
1431 scsi_kill_request(req, q);
1435 if(!get_device(&sdev->sdev_gendev))
1436 /* We must be tearing the block queue down already */
1440 * To start with, we keep looping until the queue is empty, or until
1441 * the host is no longer able to accept any more requests.
1444 while (!blk_queue_plugged(q)) {
1447 * get next queueable request. We do this early to make sure
1448 * that the request is fully prepared even if we cannot
1451 req = elv_next_request(q);
1452 if (!req || !scsi_dev_queue_ready(q, sdev))
1455 if (unlikely(!scsi_device_online(sdev))) {
1456 sdev_printk(KERN_ERR, sdev,
1457 "rejecting I/O to offline device\n");
1458 scsi_kill_request(req, q);
1464 * Remove the request from the request list.
1466 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1467 blkdev_dequeue_request(req);
1468 sdev->device_busy++;
1470 spin_unlock(q->queue_lock);
1472 if (unlikely(cmd == NULL)) {
1473 printk(KERN_CRIT "impossible request in %s.\n"
1474 "please mail a stack trace to "
1475 "linux-scsi@vger.kernel.org\n",
1477 blk_dump_rq_flags(req, "foo");
1480 spin_lock(shost->host_lock);
1482 if (!scsi_host_queue_ready(q, shost, sdev))
1484 if (scsi_target(sdev)->single_lun) {
1485 if (scsi_target(sdev)->starget_sdev_user &&
1486 scsi_target(sdev)->starget_sdev_user != sdev)
1488 scsi_target(sdev)->starget_sdev_user = sdev;
1493 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1494 * take the lock again.
1496 spin_unlock_irq(shost->host_lock);
1499 * Finally, initialize any error handling parameters, and set up
1500 * the timers for timeouts.
1502 scsi_init_cmd_errh(cmd);
1505 * Dispatch the command to the low-level driver.
1507 rtn = scsi_dispatch_cmd(cmd);
1508 spin_lock_irq(q->queue_lock);
1510 /* we're refusing the command; because of
1511 * the way locks get dropped, we need to
1512 * check here if plugging is required */
1513 if(sdev->device_busy == 0)
1523 spin_unlock_irq(shost->host_lock);
1526 * lock q, handle tag, requeue req, and decrement device_busy. We
1527 * must return with queue_lock held.
1529 * Decrementing device_busy without checking it is OK, as all such
1530 * cases (host limits or settings) should run the queue at some
1533 spin_lock_irq(q->queue_lock);
1534 blk_requeue_request(q, req);
1535 sdev->device_busy--;
1536 if(sdev->device_busy == 0)
1539 /* must be careful here...if we trigger the ->remove() function
1540 * we cannot be holding the q lock */
1541 spin_unlock_irq(q->queue_lock);
1542 put_device(&sdev->sdev_gendev);
1543 spin_lock_irq(q->queue_lock);
1546 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1548 struct device *host_dev;
1549 u64 bounce_limit = 0xffffffff;
1551 if (shost->unchecked_isa_dma)
1552 return BLK_BOUNCE_ISA;
1554 * Platforms with virtual-DMA translation
1555 * hardware have no practical limit.
1557 if (!PCI_DMA_BUS_IS_PHYS)
1558 return BLK_BOUNCE_ANY;
1560 host_dev = scsi_get_device(shost);
1561 if (host_dev && host_dev->dma_mask)
1562 bounce_limit = *host_dev->dma_mask;
1564 return bounce_limit;
1566 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1568 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1569 request_fn_proc *request_fn)
1571 struct request_queue *q;
1573 q = blk_init_queue(request_fn, NULL);
1578 * this limit is imposed by hardware restrictions
1580 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1581 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1583 blk_queue_max_sectors(q, shost->max_sectors);
1584 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1585 blk_queue_segment_boundary(q, shost->dma_boundary);
1587 if (!shost->use_clustering)
1588 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1591 * set a reasonable default alignment on word boundaries: the
1592 * host and device may alter it using
1593 * blk_queue_update_dma_alignment() later.
1595 blk_queue_dma_alignment(q, 0x03);
1599 EXPORT_SYMBOL(__scsi_alloc_queue);
1601 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1603 struct request_queue *q;
1605 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1609 blk_queue_prep_rq(q, scsi_prep_fn);
1610 blk_queue_softirq_done(q, scsi_softirq_done);
1614 void scsi_free_queue(struct request_queue *q)
1616 blk_cleanup_queue(q);
1620 * Function: scsi_block_requests()
1622 * Purpose: Utility function used by low-level drivers to prevent further
1623 * commands from being queued to the device.
1625 * Arguments: shost - Host in question
1629 * Lock status: No locks are assumed held.
1631 * Notes: There is no timer nor any other means by which the requests
1632 * get unblocked other than the low-level driver calling
1633 * scsi_unblock_requests().
1635 void scsi_block_requests(struct Scsi_Host *shost)
1637 shost->host_self_blocked = 1;
1639 EXPORT_SYMBOL(scsi_block_requests);
1642 * Function: scsi_unblock_requests()
1644 * Purpose: Utility function used by low-level drivers to allow further
1645 * commands from being queued to the device.
1647 * Arguments: shost - Host in question
1651 * Lock status: No locks are assumed held.
1653 * Notes: There is no timer nor any other means by which the requests
1654 * get unblocked other than the low-level driver calling
1655 * scsi_unblock_requests().
1657 * This is done as an API function so that changes to the
1658 * internals of the scsi mid-layer won't require wholesale
1659 * changes to drivers that use this feature.
1661 void scsi_unblock_requests(struct Scsi_Host *shost)
1663 shost->host_self_blocked = 0;
1664 scsi_run_host_queues(shost);
1666 EXPORT_SYMBOL(scsi_unblock_requests);
1668 int __init scsi_init_queue(void)
1672 scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1673 sizeof(struct scsi_io_context),
1675 if (!scsi_io_context_cache) {
1676 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1680 scsi_bidi_sdb_cache = kmem_cache_create("scsi_bidi_sdb",
1681 sizeof(struct scsi_data_buffer),
1683 if (!scsi_bidi_sdb_cache) {
1684 printk(KERN_ERR "SCSI: can't init scsi bidi sdb cache\n");
1685 goto cleanup_io_context;
1688 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1689 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1690 int size = sgp->size * sizeof(struct scatterlist);
1692 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1693 SLAB_HWCACHE_ALIGN, NULL);
1695 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1697 goto cleanup_bidi_sdb;
1700 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1703 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1705 goto cleanup_bidi_sdb;
1712 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1713 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1715 mempool_destroy(sgp->pool);
1717 kmem_cache_destroy(sgp->slab);
1719 kmem_cache_destroy(scsi_bidi_sdb_cache);
1721 kmem_cache_destroy(scsi_io_context_cache);
1726 void scsi_exit_queue(void)
1730 kmem_cache_destroy(scsi_io_context_cache);
1731 kmem_cache_destroy(scsi_bidi_sdb_cache);
1733 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1734 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1735 mempool_destroy(sgp->pool);
1736 kmem_cache_destroy(sgp->slab);
1741 * scsi_mode_select - issue a mode select
1742 * @sdev: SCSI device to be queried
1743 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1744 * @sp: Save page bit (0 == don't save, 1 == save)
1745 * @modepage: mode page being requested
1746 * @buffer: request buffer (may not be smaller than eight bytes)
1747 * @len: length of request buffer.
1748 * @timeout: command timeout
1749 * @retries: number of retries before failing
1750 * @data: returns a structure abstracting the mode header data
1751 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1752 * must be SCSI_SENSE_BUFFERSIZE big.
1754 * Returns zero if successful; negative error number or scsi
1759 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1760 unsigned char *buffer, int len, int timeout, int retries,
1761 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1763 unsigned char cmd[10];
1764 unsigned char *real_buffer;
1767 memset(cmd, 0, sizeof(cmd));
1768 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1770 if (sdev->use_10_for_ms) {
1773 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1776 memcpy(real_buffer + 8, buffer, len);
1780 real_buffer[2] = data->medium_type;
1781 real_buffer[3] = data->device_specific;
1782 real_buffer[4] = data->longlba ? 0x01 : 0;
1784 real_buffer[6] = data->block_descriptor_length >> 8;
1785 real_buffer[7] = data->block_descriptor_length;
1787 cmd[0] = MODE_SELECT_10;
1791 if (len > 255 || data->block_descriptor_length > 255 ||
1795 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1798 memcpy(real_buffer + 4, buffer, len);
1801 real_buffer[1] = data->medium_type;
1802 real_buffer[2] = data->device_specific;
1803 real_buffer[3] = data->block_descriptor_length;
1806 cmd[0] = MODE_SELECT;
1810 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1811 sshdr, timeout, retries);
1815 EXPORT_SYMBOL_GPL(scsi_mode_select);
1818 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1819 * @sdev: SCSI device to be queried
1820 * @dbd: set if mode sense will allow block descriptors to be returned
1821 * @modepage: mode page being requested
1822 * @buffer: request buffer (may not be smaller than eight bytes)
1823 * @len: length of request buffer.
1824 * @timeout: command timeout
1825 * @retries: number of retries before failing
1826 * @data: returns a structure abstracting the mode header data
1827 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1828 * must be SCSI_SENSE_BUFFERSIZE big.
1830 * Returns zero if unsuccessful, or the header offset (either 4
1831 * or 8 depending on whether a six or ten byte command was
1832 * issued) if successful.
1835 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1836 unsigned char *buffer, int len, int timeout, int retries,
1837 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1839 unsigned char cmd[12];
1843 struct scsi_sense_hdr my_sshdr;
1845 memset(data, 0, sizeof(*data));
1846 memset(&cmd[0], 0, 12);
1847 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1850 /* caller might not be interested in sense, but we need it */
1855 use_10_for_ms = sdev->use_10_for_ms;
1857 if (use_10_for_ms) {
1861 cmd[0] = MODE_SENSE_10;
1868 cmd[0] = MODE_SENSE;
1873 memset(buffer, 0, len);
1875 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1876 sshdr, timeout, retries);
1878 /* This code looks awful: what it's doing is making sure an
1879 * ILLEGAL REQUEST sense return identifies the actual command
1880 * byte as the problem. MODE_SENSE commands can return
1881 * ILLEGAL REQUEST if the code page isn't supported */
1883 if (use_10_for_ms && !scsi_status_is_good(result) &&
1884 (driver_byte(result) & DRIVER_SENSE)) {
1885 if (scsi_sense_valid(sshdr)) {
1886 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1887 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1889 * Invalid command operation code
1891 sdev->use_10_for_ms = 0;
1897 if(scsi_status_is_good(result)) {
1898 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1899 (modepage == 6 || modepage == 8))) {
1900 /* Initio breakage? */
1903 data->medium_type = 0;
1904 data->device_specific = 0;
1906 data->block_descriptor_length = 0;
1907 } else if(use_10_for_ms) {
1908 data->length = buffer[0]*256 + buffer[1] + 2;
1909 data->medium_type = buffer[2];
1910 data->device_specific = buffer[3];
1911 data->longlba = buffer[4] & 0x01;
1912 data->block_descriptor_length = buffer[6]*256
1915 data->length = buffer[0] + 1;
1916 data->medium_type = buffer[1];
1917 data->device_specific = buffer[2];
1918 data->block_descriptor_length = buffer[3];
1920 data->header_length = header_length;
1925 EXPORT_SYMBOL(scsi_mode_sense);
1928 * scsi_test_unit_ready - test if unit is ready
1929 * @sdev: scsi device to change the state of.
1930 * @timeout: command timeout
1931 * @retries: number of retries before failing
1932 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
1933 * returning sense. Make sure that this is cleared before passing
1936 * Returns zero if unsuccessful or an error if TUR failed. For
1937 * removable media, a return of NOT_READY or UNIT_ATTENTION is
1938 * translated to success, with the ->changed flag updated.
1941 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
1942 struct scsi_sense_hdr *sshdr_external)
1945 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1947 struct scsi_sense_hdr *sshdr;
1950 if (!sshdr_external)
1951 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
1953 sshdr = sshdr_external;
1955 /* try to eat the UNIT_ATTENTION if there are enough retries */
1957 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
1959 } while ((driver_byte(result) & DRIVER_SENSE) &&
1960 sshdr && sshdr->sense_key == UNIT_ATTENTION &&
1964 /* could not allocate sense buffer, so can't process it */
1967 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
1969 if ((scsi_sense_valid(sshdr)) &&
1970 ((sshdr->sense_key == UNIT_ATTENTION) ||
1971 (sshdr->sense_key == NOT_READY))) {
1976 if (!sshdr_external)
1980 EXPORT_SYMBOL(scsi_test_unit_ready);
1983 * scsi_device_set_state - Take the given device through the device state model.
1984 * @sdev: scsi device to change the state of.
1985 * @state: state to change to.
1987 * Returns zero if unsuccessful or an error if the requested
1988 * transition is illegal.
1991 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1993 enum scsi_device_state oldstate = sdev->sdev_state;
1995 if (state == oldstate)
2000 /* There are no legal states that come back to
2001 * created. This is the manually initialised start
2075 sdev->sdev_state = state;
2079 SCSI_LOG_ERROR_RECOVERY(1,
2080 sdev_printk(KERN_ERR, sdev,
2081 "Illegal state transition %s->%s\n",
2082 scsi_device_state_name(oldstate),
2083 scsi_device_state_name(state))
2087 EXPORT_SYMBOL(scsi_device_set_state);
2090 * sdev_evt_emit - emit a single SCSI device uevent
2091 * @sdev: associated SCSI device
2092 * @evt: event to emit
2094 * Send a single uevent (scsi_event) to the associated scsi_device.
2096 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2101 switch (evt->evt_type) {
2102 case SDEV_EVT_MEDIA_CHANGE:
2103 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2113 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2117 * sdev_evt_thread - send a uevent for each scsi event
2118 * @work: work struct for scsi_device
2120 * Dispatch queued events to their associated scsi_device kobjects
2123 void scsi_evt_thread(struct work_struct *work)
2125 struct scsi_device *sdev;
2126 LIST_HEAD(event_list);
2128 sdev = container_of(work, struct scsi_device, event_work);
2131 struct scsi_event *evt;
2132 struct list_head *this, *tmp;
2133 unsigned long flags;
2135 spin_lock_irqsave(&sdev->list_lock, flags);
2136 list_splice_init(&sdev->event_list, &event_list);
2137 spin_unlock_irqrestore(&sdev->list_lock, flags);
2139 if (list_empty(&event_list))
2142 list_for_each_safe(this, tmp, &event_list) {
2143 evt = list_entry(this, struct scsi_event, node);
2144 list_del(&evt->node);
2145 scsi_evt_emit(sdev, evt);
2152 * sdev_evt_send - send asserted event to uevent thread
2153 * @sdev: scsi_device event occurred on
2154 * @evt: event to send
2156 * Assert scsi device event asynchronously.
2158 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2160 unsigned long flags;
2162 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2167 spin_lock_irqsave(&sdev->list_lock, flags);
2168 list_add_tail(&evt->node, &sdev->event_list);
2169 schedule_work(&sdev->event_work);
2170 spin_unlock_irqrestore(&sdev->list_lock, flags);
2172 EXPORT_SYMBOL_GPL(sdev_evt_send);
2175 * sdev_evt_alloc - allocate a new scsi event
2176 * @evt_type: type of event to allocate
2177 * @gfpflags: GFP flags for allocation
2179 * Allocates and returns a new scsi_event.
2181 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2184 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2188 evt->evt_type = evt_type;
2189 INIT_LIST_HEAD(&evt->node);
2191 /* evt_type-specific initialization, if any */
2193 case SDEV_EVT_MEDIA_CHANGE:
2201 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2204 * sdev_evt_send_simple - send asserted event to uevent thread
2205 * @sdev: scsi_device event occurred on
2206 * @evt_type: type of event to send
2207 * @gfpflags: GFP flags for allocation
2209 * Assert scsi device event asynchronously, given an event type.
2211 void sdev_evt_send_simple(struct scsi_device *sdev,
2212 enum scsi_device_event evt_type, gfp_t gfpflags)
2214 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2216 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2221 sdev_evt_send(sdev, evt);
2223 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2226 * scsi_device_quiesce - Block user issued commands.
2227 * @sdev: scsi device to quiesce.
2229 * This works by trying to transition to the SDEV_QUIESCE state
2230 * (which must be a legal transition). When the device is in this
2231 * state, only special requests will be accepted, all others will
2232 * be deferred. Since special requests may also be requeued requests,
2233 * a successful return doesn't guarantee the device will be
2234 * totally quiescent.
2236 * Must be called with user context, may sleep.
2238 * Returns zero if unsuccessful or an error if not.
2241 scsi_device_quiesce(struct scsi_device *sdev)
2243 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2247 scsi_run_queue(sdev->request_queue);
2248 while (sdev->device_busy) {
2249 msleep_interruptible(200);
2250 scsi_run_queue(sdev->request_queue);
2254 EXPORT_SYMBOL(scsi_device_quiesce);
2257 * scsi_device_resume - Restart user issued commands to a quiesced device.
2258 * @sdev: scsi device to resume.
2260 * Moves the device from quiesced back to running and restarts the
2263 * Must be called with user context, may sleep.
2266 scsi_device_resume(struct scsi_device *sdev)
2268 if(scsi_device_set_state(sdev, SDEV_RUNNING))
2270 scsi_run_queue(sdev->request_queue);
2272 EXPORT_SYMBOL(scsi_device_resume);
2275 device_quiesce_fn(struct scsi_device *sdev, void *data)
2277 scsi_device_quiesce(sdev);
2281 scsi_target_quiesce(struct scsi_target *starget)
2283 starget_for_each_device(starget, NULL, device_quiesce_fn);
2285 EXPORT_SYMBOL(scsi_target_quiesce);
2288 device_resume_fn(struct scsi_device *sdev, void *data)
2290 scsi_device_resume(sdev);
2294 scsi_target_resume(struct scsi_target *starget)
2296 starget_for_each_device(starget, NULL, device_resume_fn);
2298 EXPORT_SYMBOL(scsi_target_resume);
2301 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2302 * @sdev: device to block
2304 * Block request made by scsi lld's to temporarily stop all
2305 * scsi commands on the specified device. Called from interrupt
2306 * or normal process context.
2308 * Returns zero if successful or error if not
2311 * This routine transitions the device to the SDEV_BLOCK state
2312 * (which must be a legal transition). When the device is in this
2313 * state, all commands are deferred until the scsi lld reenables
2314 * the device with scsi_device_unblock or device_block_tmo fires.
2315 * This routine assumes the host_lock is held on entry.
2318 scsi_internal_device_block(struct scsi_device *sdev)
2320 struct request_queue *q = sdev->request_queue;
2321 unsigned long flags;
2324 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2329 * The device has transitioned to SDEV_BLOCK. Stop the
2330 * block layer from calling the midlayer with this device's
2333 spin_lock_irqsave(q->queue_lock, flags);
2335 spin_unlock_irqrestore(q->queue_lock, flags);
2339 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2342 * scsi_internal_device_unblock - resume a device after a block request
2343 * @sdev: device to resume
2345 * Called by scsi lld's or the midlayer to restart the device queue
2346 * for the previously suspended scsi device. Called from interrupt or
2347 * normal process context.
2349 * Returns zero if successful or error if not.
2352 * This routine transitions the device to the SDEV_RUNNING state
2353 * (which must be a legal transition) allowing the midlayer to
2354 * goose the queue for this device. This routine assumes the
2355 * host_lock is held upon entry.
2358 scsi_internal_device_unblock(struct scsi_device *sdev)
2360 struct request_queue *q = sdev->request_queue;
2362 unsigned long flags;
2365 * Try to transition the scsi device to SDEV_RUNNING
2366 * and goose the device queue if successful.
2368 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2372 spin_lock_irqsave(q->queue_lock, flags);
2374 spin_unlock_irqrestore(q->queue_lock, flags);
2378 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2381 device_block(struct scsi_device *sdev, void *data)
2383 scsi_internal_device_block(sdev);
2387 target_block(struct device *dev, void *data)
2389 if (scsi_is_target_device(dev))
2390 starget_for_each_device(to_scsi_target(dev), NULL,
2396 scsi_target_block(struct device *dev)
2398 if (scsi_is_target_device(dev))
2399 starget_for_each_device(to_scsi_target(dev), NULL,
2402 device_for_each_child(dev, NULL, target_block);
2404 EXPORT_SYMBOL_GPL(scsi_target_block);
2407 device_unblock(struct scsi_device *sdev, void *data)
2409 scsi_internal_device_unblock(sdev);
2413 target_unblock(struct device *dev, void *data)
2415 if (scsi_is_target_device(dev))
2416 starget_for_each_device(to_scsi_target(dev), NULL,
2422 scsi_target_unblock(struct device *dev)
2424 if (scsi_is_target_device(dev))
2425 starget_for_each_device(to_scsi_target(dev), NULL,
2428 device_for_each_child(dev, NULL, target_unblock);
2430 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2433 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2434 * @sgl: scatter-gather list
2435 * @sg_count: number of segments in sg
2436 * @offset: offset in bytes into sg, on return offset into the mapped area
2437 * @len: bytes to map, on return number of bytes mapped
2439 * Returns virtual address of the start of the mapped page
2441 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2442 size_t *offset, size_t *len)
2445 size_t sg_len = 0, len_complete = 0;
2446 struct scatterlist *sg;
2449 WARN_ON(!irqs_disabled());
2451 for_each_sg(sgl, sg, sg_count, i) {
2452 len_complete = sg_len; /* Complete sg-entries */
2453 sg_len += sg->length;
2454 if (sg_len > *offset)
2458 if (unlikely(i == sg_count)) {
2459 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2461 __FUNCTION__, sg_len, *offset, sg_count);
2466 /* Offset starting from the beginning of first page in this sg-entry */
2467 *offset = *offset - len_complete + sg->offset;
2469 /* Assumption: contiguous pages can be accessed as "page + i" */
2470 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2471 *offset &= ~PAGE_MASK;
2473 /* Bytes in this sg-entry from *offset to the end of the page */
2474 sg_len = PAGE_SIZE - *offset;
2478 return kmap_atomic(page, KM_BIO_SRC_IRQ);
2480 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2483 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2484 * @virt: virtual address to be unmapped
2486 void scsi_kunmap_atomic_sg(void *virt)
2488 kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2490 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);