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 struct kmem_cache
*scsi_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);
211 * Some devices (USB mass-storage in particular) may transfer
212 * garbage data together with a residue indicating that the data
213 * is invalid. Prevent the garbage from being misinterpreted
214 * and prevent security leaks by zeroing out the excess data.
216 if (unlikely(req
->data_len
> 0 && req
->data_len
<= bufflen
))
217 memset(buffer
+ (bufflen
- req
->data_len
), 0, req
->data_len
);
221 blk_put_request(req
);
225 EXPORT_SYMBOL(scsi_execute
);
228 int scsi_execute_req(struct scsi_device
*sdev
, const unsigned char *cmd
,
229 int data_direction
, void *buffer
, unsigned bufflen
,
230 struct scsi_sense_hdr
*sshdr
, int timeout
, int retries
)
236 sense
= kzalloc(SCSI_SENSE_BUFFERSIZE
, GFP_NOIO
);
238 return DRIVER_ERROR
<< 24;
240 result
= scsi_execute(sdev
, cmd
, data_direction
, buffer
, bufflen
,
241 sense
, timeout
, retries
, 0);
243 scsi_normalize_sense(sense
, SCSI_SENSE_BUFFERSIZE
, sshdr
);
248 EXPORT_SYMBOL(scsi_execute_req
);
250 struct scsi_io_context
{
252 void (*done
)(void *data
, char *sense
, int result
, int resid
);
253 char sense
[SCSI_SENSE_BUFFERSIZE
];
256 static struct kmem_cache
*scsi_io_context_cache
;
258 static void scsi_end_async(struct request
*req
, int uptodate
)
260 struct scsi_io_context
*sioc
= req
->end_io_data
;
263 sioc
->done(sioc
->data
, sioc
->sense
, req
->errors
, req
->data_len
);
265 kmem_cache_free(scsi_io_context_cache
, sioc
);
266 __blk_put_request(req
->q
, req
);
269 static int scsi_merge_bio(struct request
*rq
, struct bio
*bio
)
271 struct request_queue
*q
= rq
->q
;
273 bio
->bi_flags
&= ~(1 << BIO_SEG_VALID
);
274 if (rq_data_dir(rq
) == WRITE
)
275 bio
->bi_rw
|= (1 << BIO_RW
);
276 blk_queue_bounce(q
, &bio
);
278 return blk_rq_append_bio(q
, rq
, bio
);
281 static void scsi_bi_endio(struct bio
*bio
, int error
)
287 * scsi_req_map_sg - map a scatterlist into a request
288 * @rq: request to fill
290 * @nsegs: number of elements
291 * @bufflen: len of buffer
292 * @gfp: memory allocation flags
294 * scsi_req_map_sg maps a scatterlist into a request so that the
295 * request can be sent to the block layer. We do not trust the scatterlist
296 * sent to use, as some ULDs use that struct to only organize the pages.
298 static int scsi_req_map_sg(struct request
*rq
, struct scatterlist
*sgl
,
299 int nsegs
, unsigned bufflen
, gfp_t gfp
)
301 struct request_queue
*q
= rq
->q
;
302 int nr_pages
= (bufflen
+ sgl
[0].offset
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
303 unsigned int data_len
= bufflen
, len
, bytes
, off
;
304 struct scatterlist
*sg
;
306 struct bio
*bio
= NULL
;
307 int i
, err
, nr_vecs
= 0;
309 for_each_sg(sgl
, sg
, nsegs
, i
) {
314 while (len
> 0 && data_len
> 0) {
316 * sg sends a scatterlist that is larger than
317 * the data_len it wants transferred for certain
320 bytes
= min_t(unsigned int, len
, PAGE_SIZE
- off
);
321 bytes
= min(bytes
, data_len
);
324 nr_vecs
= min_t(int, BIO_MAX_PAGES
, nr_pages
);
327 bio
= bio_alloc(gfp
, nr_vecs
);
332 bio
->bi_end_io
= scsi_bi_endio
;
335 if (bio_add_pc_page(q
, bio
, page
, bytes
, off
) !=
342 if (bio
->bi_vcnt
>= nr_vecs
) {
343 err
= scsi_merge_bio(rq
, bio
);
358 rq
->buffer
= rq
->data
= NULL
;
359 rq
->data_len
= bufflen
;
363 while ((bio
= rq
->bio
) != NULL
) {
364 rq
->bio
= bio
->bi_next
;
366 * call endio instead of bio_put incase it was bounced
375 * scsi_execute_async - insert request
378 * @cmd_len: length of scsi cdb
379 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
380 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
381 * @bufflen: len of buffer
382 * @use_sg: if buffer is a scatterlist this is the number of elements
383 * @timeout: request timeout in seconds
384 * @retries: number of times to retry request
385 * @privdata: data passed to done()
386 * @done: callback function when done
387 * @gfp: memory allocation flags
389 int scsi_execute_async(struct scsi_device
*sdev
, const unsigned char *cmd
,
390 int cmd_len
, int data_direction
, void *buffer
, unsigned bufflen
,
391 int use_sg
, int timeout
, int retries
, void *privdata
,
392 void (*done
)(void *, char *, int, int), gfp_t gfp
)
395 struct scsi_io_context
*sioc
;
397 int write
= (data_direction
== DMA_TO_DEVICE
);
399 sioc
= kmem_cache_zalloc(scsi_io_context_cache
, gfp
);
401 return DRIVER_ERROR
<< 24;
403 req
= blk_get_request(sdev
->request_queue
, write
, gfp
);
406 req
->cmd_type
= REQ_TYPE_BLOCK_PC
;
407 req
->cmd_flags
|= REQ_QUIET
;
410 err
= scsi_req_map_sg(req
, buffer
, use_sg
, bufflen
, gfp
);
412 err
= blk_rq_map_kern(req
->q
, req
, buffer
, bufflen
, gfp
);
417 req
->cmd_len
= cmd_len
;
418 memset(req
->cmd
, 0, BLK_MAX_CDB
); /* ATAPI hates garbage after CDB */
419 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
420 req
->sense
= sioc
->sense
;
422 req
->timeout
= timeout
;
423 req
->retries
= retries
;
424 req
->end_io_data
= sioc
;
426 sioc
->data
= privdata
;
429 blk_execute_rq_nowait(req
->q
, NULL
, req
, 1, scsi_end_async
);
433 blk_put_request(req
);
435 kmem_cache_free(scsi_io_context_cache
, sioc
);
436 return DRIVER_ERROR
<< 24;
438 EXPORT_SYMBOL_GPL(scsi_execute_async
);
441 * Function: scsi_init_cmd_errh()
443 * Purpose: Initialize cmd fields related to error handling.
445 * Arguments: cmd - command that is ready to be queued.
447 * Notes: This function has the job of initializing a number of
448 * fields related to error handling. Typically this will
449 * be called once for each command, as required.
451 static void scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
453 cmd
->serial_number
= 0;
454 scsi_set_resid(cmd
, 0);
455 memset(cmd
->sense_buffer
, 0, SCSI_SENSE_BUFFERSIZE
);
456 if (cmd
->cmd_len
== 0)
457 cmd
->cmd_len
= scsi_command_size(cmd
->cmnd
);
460 void scsi_device_unbusy(struct scsi_device
*sdev
)
462 struct Scsi_Host
*shost
= sdev
->host
;
465 spin_lock_irqsave(shost
->host_lock
, flags
);
467 if (unlikely(scsi_host_in_recovery(shost
) &&
468 (shost
->host_failed
|| shost
->host_eh_scheduled
)))
469 scsi_eh_wakeup(shost
);
470 spin_unlock(shost
->host_lock
);
471 spin_lock(sdev
->request_queue
->queue_lock
);
473 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
477 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
478 * and call blk_run_queue for all the scsi_devices on the target -
479 * including current_sdev first.
481 * Called with *no* scsi locks held.
483 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
485 struct Scsi_Host
*shost
= current_sdev
->host
;
486 struct scsi_device
*sdev
, *tmp
;
487 struct scsi_target
*starget
= scsi_target(current_sdev
);
490 spin_lock_irqsave(shost
->host_lock
, flags
);
491 starget
->starget_sdev_user
= NULL
;
492 spin_unlock_irqrestore(shost
->host_lock
, flags
);
495 * Call blk_run_queue for all LUNs on the target, starting with
496 * current_sdev. We race with others (to set starget_sdev_user),
497 * but in most cases, we will be first. Ideally, each LU on the
498 * target would get some limited time or requests on the target.
500 blk_run_queue(current_sdev
->request_queue
);
502 spin_lock_irqsave(shost
->host_lock
, flags
);
503 if (starget
->starget_sdev_user
)
505 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
506 same_target_siblings
) {
507 if (sdev
== current_sdev
)
509 if (scsi_device_get(sdev
))
512 spin_unlock_irqrestore(shost
->host_lock
, flags
);
513 blk_run_queue(sdev
->request_queue
);
514 spin_lock_irqsave(shost
->host_lock
, flags
);
516 scsi_device_put(sdev
);
519 spin_unlock_irqrestore(shost
->host_lock
, flags
);
523 * Function: scsi_run_queue()
525 * Purpose: Select a proper request queue to serve next
527 * Arguments: q - last request's queue
531 * Notes: The previous command was completely finished, start
532 * a new one if possible.
534 static void scsi_run_queue(struct request_queue
*q
)
536 struct scsi_device
*sdev
= q
->queuedata
;
537 struct Scsi_Host
*shost
= sdev
->host
;
540 if (scsi_target(sdev
)->single_lun
)
541 scsi_single_lun_run(sdev
);
543 spin_lock_irqsave(shost
->host_lock
, flags
);
544 while (!list_empty(&shost
->starved_list
) &&
545 !shost
->host_blocked
&& !shost
->host_self_blocked
&&
546 !((shost
->can_queue
> 0) &&
547 (shost
->host_busy
>= shost
->can_queue
))) {
552 * As long as shost is accepting commands and we have
553 * starved queues, call blk_run_queue. scsi_request_fn
554 * drops the queue_lock and can add us back to the
557 * host_lock protects the starved_list and starved_entry.
558 * scsi_request_fn must get the host_lock before checking
559 * or modifying starved_list or starved_entry.
561 sdev
= list_entry(shost
->starved_list
.next
,
562 struct scsi_device
, starved_entry
);
563 list_del_init(&sdev
->starved_entry
);
564 spin_unlock(shost
->host_lock
);
566 spin_lock(sdev
->request_queue
->queue_lock
);
567 flagset
= test_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
) &&
568 !test_bit(QUEUE_FLAG_REENTER
,
569 &sdev
->request_queue
->queue_flags
);
571 queue_flag_set(QUEUE_FLAG_REENTER
, sdev
->request_queue
);
572 __blk_run_queue(sdev
->request_queue
);
574 queue_flag_clear(QUEUE_FLAG_REENTER
, sdev
->request_queue
);
575 spin_unlock(sdev
->request_queue
->queue_lock
);
577 spin_lock(shost
->host_lock
);
578 if (unlikely(!list_empty(&sdev
->starved_entry
)))
580 * sdev lost a race, and was put back on the
581 * starved list. This is unlikely but without this
582 * in theory we could loop forever.
586 spin_unlock_irqrestore(shost
->host_lock
, flags
);
592 * Function: scsi_requeue_command()
594 * Purpose: Handle post-processing of completed commands.
596 * Arguments: q - queue to operate on
597 * cmd - command that may need to be requeued.
601 * Notes: After command completion, there may be blocks left
602 * over which weren't finished by the previous command
603 * this can be for a number of reasons - the main one is
604 * I/O errors in the middle of the request, in which case
605 * we need to request the blocks that come after the bad
607 * Notes: Upon return, cmd is a stale pointer.
609 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
611 struct request
*req
= cmd
->request
;
614 scsi_unprep_request(req
);
615 spin_lock_irqsave(q
->queue_lock
, flags
);
616 blk_requeue_request(q
, req
);
617 spin_unlock_irqrestore(q
->queue_lock
, flags
);
622 void scsi_next_command(struct scsi_cmnd
*cmd
)
624 struct scsi_device
*sdev
= cmd
->device
;
625 struct request_queue
*q
= sdev
->request_queue
;
627 /* need to hold a reference on the device before we let go of the cmd */
628 get_device(&sdev
->sdev_gendev
);
630 scsi_put_command(cmd
);
633 /* ok to remove device now */
634 put_device(&sdev
->sdev_gendev
);
637 void scsi_run_host_queues(struct Scsi_Host
*shost
)
639 struct scsi_device
*sdev
;
641 shost_for_each_device(sdev
, shost
)
642 scsi_run_queue(sdev
->request_queue
);
646 * Function: scsi_end_request()
648 * Purpose: Post-processing of completed commands (usually invoked at end
649 * of upper level post-processing and scsi_io_completion).
651 * Arguments: cmd - command that is complete.
652 * error - 0 if I/O indicates success, < 0 for I/O error.
653 * bytes - number of bytes of completed I/O
654 * requeue - indicates whether we should requeue leftovers.
656 * Lock status: Assumed that lock is not held upon entry.
658 * Returns: cmd if requeue required, NULL otherwise.
660 * Notes: This is called for block device requests in order to
661 * mark some number of sectors as complete.
663 * We are guaranteeing that the request queue will be goosed
664 * at some point during this call.
665 * Notes: If cmd was requeued, upon return it will be a stale pointer.
667 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int error
,
668 int bytes
, int requeue
)
670 struct request_queue
*q
= cmd
->device
->request_queue
;
671 struct request
*req
= cmd
->request
;
674 * If there are blocks left over at the end, set up the command
675 * to queue the remainder of them.
677 if (blk_end_request(req
, error
, bytes
)) {
678 int leftover
= (req
->hard_nr_sectors
<< 9);
680 if (blk_pc_request(req
))
681 leftover
= req
->data_len
;
683 /* kill remainder if no retrys */
684 if (error
&& blk_noretry_request(req
))
685 blk_end_request(req
, error
, leftover
);
689 * Bleah. Leftovers again. Stick the
690 * leftovers in the front of the
691 * queue, and goose the queue again.
693 scsi_requeue_command(q
, cmd
);
701 * This will goose the queue request function at the end, so we don't
702 * need to worry about launching another command.
704 scsi_next_command(cmd
);
708 static inline unsigned int scsi_sgtable_index(unsigned short nents
)
712 BUG_ON(nents
> SCSI_MAX_SG_SEGMENTS
);
717 index
= get_count_order(nents
) - 3;
722 static void scsi_sg_free(struct scatterlist
*sgl
, unsigned int nents
)
724 struct scsi_host_sg_pool
*sgp
;
726 sgp
= scsi_sg_pools
+ scsi_sgtable_index(nents
);
727 mempool_free(sgl
, sgp
->pool
);
730 static struct scatterlist
*scsi_sg_alloc(unsigned int nents
, gfp_t gfp_mask
)
732 struct scsi_host_sg_pool
*sgp
;
734 sgp
= scsi_sg_pools
+ scsi_sgtable_index(nents
);
735 return mempool_alloc(sgp
->pool
, gfp_mask
);
738 static int scsi_alloc_sgtable(struct scsi_data_buffer
*sdb
, int nents
,
745 ret
= __sg_alloc_table(&sdb
->table
, nents
, SCSI_MAX_SG_SEGMENTS
,
746 gfp_mask
, scsi_sg_alloc
);
748 __sg_free_table(&sdb
->table
, SCSI_MAX_SG_SEGMENTS
,
754 static void scsi_free_sgtable(struct scsi_data_buffer
*sdb
)
756 __sg_free_table(&sdb
->table
, SCSI_MAX_SG_SEGMENTS
, scsi_sg_free
);
760 * Function: scsi_release_buffers()
762 * Purpose: Completion processing for block device I/O requests.
764 * Arguments: cmd - command that we are bailing.
766 * Lock status: Assumed that no lock is held upon entry.
770 * Notes: In the event that an upper level driver rejects a
771 * command, we must release resources allocated during
772 * the __init_io() function. Primarily this would involve
773 * the scatter-gather table, and potentially any bounce
776 void scsi_release_buffers(struct scsi_cmnd
*cmd
)
778 if (cmd
->sdb
.table
.nents
)
779 scsi_free_sgtable(&cmd
->sdb
);
781 memset(&cmd
->sdb
, 0, sizeof(cmd
->sdb
));
783 if (scsi_bidi_cmnd(cmd
)) {
784 struct scsi_data_buffer
*bidi_sdb
=
785 cmd
->request
->next_rq
->special
;
786 scsi_free_sgtable(bidi_sdb
);
787 kmem_cache_free(scsi_sdb_cache
, bidi_sdb
);
788 cmd
->request
->next_rq
->special
= NULL
;
791 if (scsi_prot_sg_count(cmd
))
792 scsi_free_sgtable(cmd
->prot_sdb
);
794 EXPORT_SYMBOL(scsi_release_buffers
);
797 * Bidi commands Must be complete as a whole, both sides at once.
798 * If part of the bytes were written and lld returned
799 * scsi_in()->resid and/or scsi_out()->resid this information will be left
800 * in req->data_len and req->next_rq->data_len. The upper-layer driver can
801 * decide what to do with this information.
803 static void scsi_end_bidi_request(struct scsi_cmnd
*cmd
)
805 struct request
*req
= cmd
->request
;
806 unsigned int dlen
= req
->data_len
;
807 unsigned int next_dlen
= req
->next_rq
->data_len
;
809 req
->data_len
= scsi_out(cmd
)->resid
;
810 req
->next_rq
->data_len
= scsi_in(cmd
)->resid
;
812 /* The req and req->next_rq have not been completed */
813 BUG_ON(blk_end_bidi_request(req
, 0, dlen
, next_dlen
));
815 scsi_release_buffers(cmd
);
818 * This will goose the queue request function at the end, so we don't
819 * need to worry about launching another command.
821 scsi_next_command(cmd
);
825 * Function: scsi_io_completion()
827 * Purpose: Completion processing for block device I/O requests.
829 * Arguments: cmd - command that is finished.
831 * Lock status: Assumed that no lock is held upon entry.
835 * Notes: This function is matched in terms of capabilities to
836 * the function that created the scatter-gather list.
837 * In other words, if there are no bounce buffers
838 * (the normal case for most drivers), we don't need
839 * the logic to deal with cleaning up afterwards.
841 * We must do one of several things here:
843 * a) Call scsi_end_request. This will finish off the
844 * specified number of sectors. If we are done, the
845 * command block will be released, and the queue
846 * function will be goosed. If we are not done, then
847 * scsi_end_request will directly goose the queue.
849 * b) We can just use scsi_requeue_command() here. This would
850 * be used if we just wanted to retry, for example.
852 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
)
854 int result
= cmd
->result
;
856 struct request_queue
*q
= cmd
->device
->request_queue
;
857 struct request
*req
= cmd
->request
;
859 struct scsi_sense_hdr sshdr
;
861 int sense_deferred
= 0;
864 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
866 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
869 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
870 req
->errors
= result
;
872 if (sense_valid
&& req
->sense
) {
874 * SG_IO wants current and deferred errors
876 int len
= 8 + cmd
->sense_buffer
[7];
878 if (len
> SCSI_SENSE_BUFFERSIZE
)
879 len
= SCSI_SENSE_BUFFERSIZE
;
880 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
881 req
->sense_len
= len
;
886 if (scsi_bidi_cmnd(cmd
)) {
887 /* will also release_buffers */
888 scsi_end_bidi_request(cmd
);
891 req
->data_len
= scsi_get_resid(cmd
);
894 BUG_ON(blk_bidi_rq(req
)); /* bidi not support for !blk_pc_request yet */
895 scsi_release_buffers(cmd
);
898 * Next deal with any sectors which we were able to correctly
901 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
903 req
->nr_sectors
, good_bytes
));
905 /* A number of bytes were successfully read. If there
906 * are leftovers and there is some kind of error
907 * (result != 0), retry the rest.
909 if (scsi_end_request(cmd
, error
, good_bytes
, result
== 0) == NULL
)
911 this_count
= blk_rq_bytes(req
);
913 /* good_bytes = 0, or (inclusive) there were leftovers and
914 * result = 0, so scsi_end_request couldn't retry.
916 if (sense_valid
&& !sense_deferred
) {
917 switch (sshdr
.sense_key
) {
919 if (cmd
->device
->removable
) {
920 /* Detected disc change. Set a bit
921 * and quietly refuse further access.
923 cmd
->device
->changed
= 1;
924 scsi_end_request(cmd
, -EIO
, this_count
, 1);
927 /* Must have been a power glitch, or a
928 * bus reset. Could not have been a
929 * media change, so we just retry the
930 * request and see what happens.
932 scsi_requeue_command(q
, cmd
);
936 case ILLEGAL_REQUEST
:
937 /* If we had an ILLEGAL REQUEST returned, then
938 * we may have performed an unsupported
939 * command. The only thing this should be
940 * would be a ten byte read where only a six
941 * byte read was supported. Also, on a system
942 * where READ CAPACITY failed, we may have
943 * read past the end of the disk.
945 if ((cmd
->device
->use_10_for_rw
&&
946 sshdr
.asc
== 0x20 && sshdr
.ascq
== 0x00) &&
947 (cmd
->cmnd
[0] == READ_10
||
948 cmd
->cmnd
[0] == WRITE_10
)) {
949 cmd
->device
->use_10_for_rw
= 0;
950 /* This will cause a retry with a
953 scsi_requeue_command(q
, cmd
);
954 } else if (sshdr
.asc
== 0x10) /* DIX */
955 scsi_end_request(cmd
, -EIO
, this_count
, 0);
957 scsi_end_request(cmd
, -EIO
, this_count
, 1);
959 case ABORTED_COMMAND
:
960 if (sshdr
.asc
== 0x10) { /* DIF */
961 scsi_end_request(cmd
, -EIO
, this_count
, 0);
966 /* If the device is in the process of becoming
967 * ready, or has a temporary blockage, retry.
969 if (sshdr
.asc
== 0x04) {
970 switch (sshdr
.ascq
) {
971 case 0x01: /* becoming ready */
972 case 0x04: /* format in progress */
973 case 0x05: /* rebuild in progress */
974 case 0x06: /* recalculation in progress */
975 case 0x07: /* operation in progress */
976 case 0x08: /* Long write in progress */
977 case 0x09: /* self test in progress */
978 scsi_requeue_command(q
, cmd
);
984 if (!(req
->cmd_flags
& REQ_QUIET
))
985 scsi_cmd_print_sense_hdr(cmd
,
989 scsi_end_request(cmd
, -EIO
, this_count
, 1);
991 case VOLUME_OVERFLOW
:
992 if (!(req
->cmd_flags
& REQ_QUIET
)) {
993 scmd_printk(KERN_INFO
, cmd
,
994 "Volume overflow, CDB: ");
995 __scsi_print_command(cmd
->cmnd
);
996 scsi_print_sense("", cmd
);
998 /* See SSC3rXX or current. */
999 scsi_end_request(cmd
, -EIO
, this_count
, 1);
1005 if (host_byte(result
) == DID_RESET
) {
1006 /* Third party bus reset or reset for error recovery
1007 * reasons. Just retry the request and see what
1010 scsi_requeue_command(q
, cmd
);
1014 if (!(req
->cmd_flags
& REQ_QUIET
)) {
1015 scsi_print_result(cmd
);
1016 if (driver_byte(result
) & DRIVER_SENSE
)
1017 scsi_print_sense("", cmd
);
1020 scsi_end_request(cmd
, -EIO
, this_count
, !result
);
1023 static int scsi_init_sgtable(struct request
*req
, struct scsi_data_buffer
*sdb
,
1029 * If sg table allocation fails, requeue request later.
1031 if (unlikely(scsi_alloc_sgtable(sdb
, req
->nr_phys_segments
,
1033 return BLKPREP_DEFER
;
1039 * Next, walk the list, and fill in the addresses and sizes of
1042 count
= blk_rq_map_sg(req
->q
, req
, sdb
->table
.sgl
);
1043 BUG_ON(count
> sdb
->table
.nents
);
1044 sdb
->table
.nents
= count
;
1045 if (blk_pc_request(req
))
1046 sdb
->length
= req
->data_len
;
1048 sdb
->length
= req
->nr_sectors
<< 9;
1053 * Function: scsi_init_io()
1055 * Purpose: SCSI I/O initialize function.
1057 * Arguments: cmd - Command descriptor we wish to initialize
1059 * Returns: 0 on success
1060 * BLKPREP_DEFER if the failure is retryable
1061 * BLKPREP_KILL if the failure is fatal
1063 int scsi_init_io(struct scsi_cmnd
*cmd
, gfp_t gfp_mask
)
1065 int error
= scsi_init_sgtable(cmd
->request
, &cmd
->sdb
, gfp_mask
);
1069 if (blk_bidi_rq(cmd
->request
)) {
1070 struct scsi_data_buffer
*bidi_sdb
= kmem_cache_zalloc(
1071 scsi_sdb_cache
, GFP_ATOMIC
);
1073 error
= BLKPREP_DEFER
;
1077 cmd
->request
->next_rq
->special
= bidi_sdb
;
1078 error
= scsi_init_sgtable(cmd
->request
->next_rq
, bidi_sdb
,
1084 if (blk_integrity_rq(cmd
->request
)) {
1085 struct scsi_data_buffer
*prot_sdb
= cmd
->prot_sdb
;
1088 BUG_ON(prot_sdb
== NULL
);
1089 ivecs
= blk_rq_count_integrity_sg(cmd
->request
);
1091 if (scsi_alloc_sgtable(prot_sdb
, ivecs
, gfp_mask
)) {
1092 error
= BLKPREP_DEFER
;
1096 count
= blk_rq_map_integrity_sg(cmd
->request
,
1097 prot_sdb
->table
.sgl
);
1098 BUG_ON(unlikely(count
> ivecs
));
1100 cmd
->prot_sdb
= prot_sdb
;
1101 cmd
->prot_sdb
->table
.nents
= count
;
1107 scsi_release_buffers(cmd
);
1108 if (error
== BLKPREP_KILL
)
1109 scsi_put_command(cmd
);
1110 else /* BLKPREP_DEFER */
1111 scsi_unprep_request(cmd
->request
);
1115 EXPORT_SYMBOL(scsi_init_io
);
1117 static struct scsi_cmnd
*scsi_get_cmd_from_req(struct scsi_device
*sdev
,
1118 struct request
*req
)
1120 struct scsi_cmnd
*cmd
;
1122 if (!req
->special
) {
1123 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1131 /* pull a tag out of the request if we have one */
1132 cmd
->tag
= req
->tag
;
1135 cmd
->cmnd
= req
->cmd
;
1140 int scsi_setup_blk_pc_cmnd(struct scsi_device
*sdev
, struct request
*req
)
1142 struct scsi_cmnd
*cmd
;
1143 int ret
= scsi_prep_state_check(sdev
, req
);
1145 if (ret
!= BLKPREP_OK
)
1148 cmd
= scsi_get_cmd_from_req(sdev
, req
);
1150 return BLKPREP_DEFER
;
1153 * BLOCK_PC requests may transfer data, in which case they must
1154 * a bio attached to them. Or they might contain a SCSI command
1155 * that does not transfer data, in which case they may optionally
1156 * submit a request without an attached bio.
1161 BUG_ON(!req
->nr_phys_segments
);
1163 ret
= scsi_init_io(cmd
, GFP_ATOMIC
);
1167 BUG_ON(req
->data_len
);
1170 memset(&cmd
->sdb
, 0, sizeof(cmd
->sdb
));
1174 cmd
->cmd_len
= req
->cmd_len
;
1176 cmd
->sc_data_direction
= DMA_NONE
;
1177 else if (rq_data_dir(req
) == WRITE
)
1178 cmd
->sc_data_direction
= DMA_TO_DEVICE
;
1180 cmd
->sc_data_direction
= DMA_FROM_DEVICE
;
1182 cmd
->transfersize
= req
->data_len
;
1183 cmd
->allowed
= req
->retries
;
1184 cmd
->timeout_per_command
= req
->timeout
;
1187 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd
);
1190 * Setup a REQ_TYPE_FS command. These are simple read/write request
1191 * from filesystems that still need to be translated to SCSI CDBs from
1194 int scsi_setup_fs_cmnd(struct scsi_device
*sdev
, struct request
*req
)
1196 struct scsi_cmnd
*cmd
;
1197 int ret
= scsi_prep_state_check(sdev
, req
);
1199 if (ret
!= BLKPREP_OK
)
1202 if (unlikely(sdev
->scsi_dh_data
&& sdev
->scsi_dh_data
->scsi_dh
1203 && sdev
->scsi_dh_data
->scsi_dh
->prep_fn
)) {
1204 ret
= sdev
->scsi_dh_data
->scsi_dh
->prep_fn(sdev
, req
);
1205 if (ret
!= BLKPREP_OK
)
1210 * Filesystem requests must transfer data.
1212 BUG_ON(!req
->nr_phys_segments
);
1214 cmd
= scsi_get_cmd_from_req(sdev
, req
);
1216 return BLKPREP_DEFER
;
1218 memset(cmd
->cmnd
, 0, BLK_MAX_CDB
);
1219 return scsi_init_io(cmd
, GFP_ATOMIC
);
1221 EXPORT_SYMBOL(scsi_setup_fs_cmnd
);
1223 int scsi_prep_state_check(struct scsi_device
*sdev
, struct request
*req
)
1225 int ret
= BLKPREP_OK
;
1228 * If the device is not in running state we will reject some
1231 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1232 switch (sdev
->sdev_state
) {
1235 * If the device is offline we refuse to process any
1236 * commands. The device must be brought online
1237 * before trying any recovery commands.
1239 sdev_printk(KERN_ERR
, sdev
,
1240 "rejecting I/O to offline device\n");
1245 * If the device is fully deleted, we refuse to
1246 * process any commands as well.
1248 sdev_printk(KERN_ERR
, sdev
,
1249 "rejecting I/O to dead device\n");
1255 * If the devices is blocked we defer normal commands.
1257 if (!(req
->cmd_flags
& REQ_PREEMPT
))
1258 ret
= BLKPREP_DEFER
;
1262 * For any other not fully online state we only allow
1263 * special commands. In particular any user initiated
1264 * command is not allowed.
1266 if (!(req
->cmd_flags
& REQ_PREEMPT
))
1273 EXPORT_SYMBOL(scsi_prep_state_check
);
1275 int scsi_prep_return(struct request_queue
*q
, struct request
*req
, int ret
)
1277 struct scsi_device
*sdev
= q
->queuedata
;
1281 req
->errors
= DID_NO_CONNECT
<< 16;
1282 /* release the command and kill it */
1284 struct scsi_cmnd
*cmd
= req
->special
;
1285 scsi_release_buffers(cmd
);
1286 scsi_put_command(cmd
);
1287 req
->special
= NULL
;
1292 * If we defer, the elv_next_request() returns NULL, but the
1293 * queue must be restarted, so we plug here if no returning
1294 * command will automatically do that.
1296 if (sdev
->device_busy
== 0)
1300 req
->cmd_flags
|= REQ_DONTPREP
;
1305 EXPORT_SYMBOL(scsi_prep_return
);
1307 int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1309 struct scsi_device
*sdev
= q
->queuedata
;
1310 int ret
= BLKPREP_KILL
;
1312 if (req
->cmd_type
== REQ_TYPE_BLOCK_PC
)
1313 ret
= scsi_setup_blk_pc_cmnd(sdev
, req
);
1314 return scsi_prep_return(q
, req
, ret
);
1318 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1321 * Called with the queue_lock held.
1323 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1324 struct scsi_device
*sdev
)
1326 if (sdev
->device_busy
>= sdev
->queue_depth
)
1328 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1330 * unblock after device_blocked iterates to zero
1332 if (--sdev
->device_blocked
== 0) {
1334 sdev_printk(KERN_INFO
, sdev
,
1335 "unblocking device at zero depth\n"));
1341 if (sdev
->device_blocked
)
1348 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1349 * return 0. We must end up running the queue again whenever 0 is
1350 * returned, else IO can hang.
1352 * Called with host_lock held.
1354 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1355 struct Scsi_Host
*shost
,
1356 struct scsi_device
*sdev
)
1358 if (scsi_host_in_recovery(shost
))
1360 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1362 * unblock after host_blocked iterates to zero
1364 if (--shost
->host_blocked
== 0) {
1366 printk("scsi%d unblocking host at zero depth\n",
1372 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
1373 shost
->host_blocked
|| shost
->host_self_blocked
) {
1374 if (list_empty(&sdev
->starved_entry
))
1375 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1379 /* We're OK to process the command, so we can't be starved */
1380 if (!list_empty(&sdev
->starved_entry
))
1381 list_del_init(&sdev
->starved_entry
);
1387 * Kill a request for a dead device
1389 static void scsi_kill_request(struct request
*req
, struct request_queue
*q
)
1391 struct scsi_cmnd
*cmd
= req
->special
;
1392 struct scsi_device
*sdev
= cmd
->device
;
1393 struct Scsi_Host
*shost
= sdev
->host
;
1395 blkdev_dequeue_request(req
);
1397 if (unlikely(cmd
== NULL
)) {
1398 printk(KERN_CRIT
"impossible request in %s.\n",
1403 scsi_init_cmd_errh(cmd
);
1404 cmd
->result
= DID_NO_CONNECT
<< 16;
1405 atomic_inc(&cmd
->device
->iorequest_cnt
);
1408 * SCSI request completion path will do scsi_device_unbusy(),
1409 * bump busy counts. To bump the counters, we need to dance
1410 * with the locks as normal issue path does.
1412 sdev
->device_busy
++;
1413 spin_unlock(sdev
->request_queue
->queue_lock
);
1414 spin_lock(shost
->host_lock
);
1416 spin_unlock(shost
->host_lock
);
1417 spin_lock(sdev
->request_queue
->queue_lock
);
1422 static void scsi_softirq_done(struct request
*rq
)
1424 struct scsi_cmnd
*cmd
= rq
->completion_data
;
1425 unsigned long wait_for
= (cmd
->allowed
+ 1) * cmd
->timeout_per_command
;
1428 INIT_LIST_HEAD(&cmd
->eh_entry
);
1430 disposition
= scsi_decide_disposition(cmd
);
1431 if (disposition
!= SUCCESS
&&
1432 time_before(cmd
->jiffies_at_alloc
+ wait_for
, jiffies
)) {
1433 sdev_printk(KERN_ERR
, cmd
->device
,
1434 "timing out command, waited %lus\n",
1436 disposition
= SUCCESS
;
1439 scsi_log_completion(cmd
, disposition
);
1441 switch (disposition
) {
1443 scsi_finish_command(cmd
);
1446 scsi_queue_insert(cmd
, SCSI_MLQUEUE_EH_RETRY
);
1448 case ADD_TO_MLQUEUE
:
1449 scsi_queue_insert(cmd
, SCSI_MLQUEUE_DEVICE_BUSY
);
1452 if (!scsi_eh_scmd_add(cmd
, 0))
1453 scsi_finish_command(cmd
);
1458 * Function: scsi_request_fn()
1460 * Purpose: Main strategy routine for SCSI.
1462 * Arguments: q - Pointer to actual queue.
1466 * Lock status: IO request lock assumed to be held when called.
1468 static void scsi_request_fn(struct request_queue
*q
)
1470 struct scsi_device
*sdev
= q
->queuedata
;
1471 struct Scsi_Host
*shost
;
1472 struct scsi_cmnd
*cmd
;
1473 struct request
*req
;
1476 printk("scsi: killing requests for dead queue\n");
1477 while ((req
= elv_next_request(q
)) != NULL
)
1478 scsi_kill_request(req
, q
);
1482 if(!get_device(&sdev
->sdev_gendev
))
1483 /* We must be tearing the block queue down already */
1487 * To start with, we keep looping until the queue is empty, or until
1488 * the host is no longer able to accept any more requests.
1491 while (!blk_queue_plugged(q
)) {
1494 * get next queueable request. We do this early to make sure
1495 * that the request is fully prepared even if we cannot
1498 req
= elv_next_request(q
);
1499 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1502 if (unlikely(!scsi_device_online(sdev
))) {
1503 sdev_printk(KERN_ERR
, sdev
,
1504 "rejecting I/O to offline device\n");
1505 scsi_kill_request(req
, q
);
1511 * Remove the request from the request list.
1513 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1514 blkdev_dequeue_request(req
);
1515 sdev
->device_busy
++;
1517 spin_unlock(q
->queue_lock
);
1519 if (unlikely(cmd
== NULL
)) {
1520 printk(KERN_CRIT
"impossible request in %s.\n"
1521 "please mail a stack trace to "
1522 "linux-scsi@vger.kernel.org\n",
1524 blk_dump_rq_flags(req
, "foo");
1527 spin_lock(shost
->host_lock
);
1530 * We hit this when the driver is using a host wide
1531 * tag map. For device level tag maps the queue_depth check
1532 * in the device ready fn would prevent us from trying
1533 * to allocate a tag. Since the map is a shared host resource
1534 * we add the dev to the starved list so it eventually gets
1535 * a run when a tag is freed.
1537 if (blk_queue_tagged(q
) && !blk_rq_tagged(req
)) {
1538 if (list_empty(&sdev
->starved_entry
))
1539 list_add_tail(&sdev
->starved_entry
,
1540 &shost
->starved_list
);
1544 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1546 if (scsi_target(sdev
)->single_lun
) {
1547 if (scsi_target(sdev
)->starget_sdev_user
&&
1548 scsi_target(sdev
)->starget_sdev_user
!= sdev
)
1550 scsi_target(sdev
)->starget_sdev_user
= sdev
;
1555 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1556 * take the lock again.
1558 spin_unlock_irq(shost
->host_lock
);
1561 * Finally, initialize any error handling parameters, and set up
1562 * the timers for timeouts.
1564 scsi_init_cmd_errh(cmd
);
1567 * Dispatch the command to the low-level driver.
1569 rtn
= scsi_dispatch_cmd(cmd
);
1570 spin_lock_irq(q
->queue_lock
);
1572 /* we're refusing the command; because of
1573 * the way locks get dropped, we need to
1574 * check here if plugging is required */
1575 if(sdev
->device_busy
== 0)
1585 spin_unlock_irq(shost
->host_lock
);
1588 * lock q, handle tag, requeue req, and decrement device_busy. We
1589 * must return with queue_lock held.
1591 * Decrementing device_busy without checking it is OK, as all such
1592 * cases (host limits or settings) should run the queue at some
1595 spin_lock_irq(q
->queue_lock
);
1596 blk_requeue_request(q
, req
);
1597 sdev
->device_busy
--;
1598 if(sdev
->device_busy
== 0)
1601 /* must be careful here...if we trigger the ->remove() function
1602 * we cannot be holding the q lock */
1603 spin_unlock_irq(q
->queue_lock
);
1604 put_device(&sdev
->sdev_gendev
);
1605 spin_lock_irq(q
->queue_lock
);
1608 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1610 struct device
*host_dev
;
1611 u64 bounce_limit
= 0xffffffff;
1613 if (shost
->unchecked_isa_dma
)
1614 return BLK_BOUNCE_ISA
;
1616 * Platforms with virtual-DMA translation
1617 * hardware have no practical limit.
1619 if (!PCI_DMA_BUS_IS_PHYS
)
1620 return BLK_BOUNCE_ANY
;
1622 host_dev
= scsi_get_device(shost
);
1623 if (host_dev
&& host_dev
->dma_mask
)
1624 bounce_limit
= *host_dev
->dma_mask
;
1626 return bounce_limit
;
1628 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1630 struct request_queue
*__scsi_alloc_queue(struct Scsi_Host
*shost
,
1631 request_fn_proc
*request_fn
)
1633 struct request_queue
*q
;
1634 struct device
*dev
= shost
->shost_gendev
.parent
;
1636 q
= blk_init_queue(request_fn
, NULL
);
1641 * this limit is imposed by hardware restrictions
1643 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1644 blk_queue_max_phys_segments(q
, SCSI_MAX_SG_CHAIN_SEGMENTS
);
1646 blk_queue_max_sectors(q
, shost
->max_sectors
);
1647 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1648 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1649 dma_set_seg_boundary(dev
, shost
->dma_boundary
);
1651 blk_queue_max_segment_size(q
, dma_get_max_seg_size(dev
));
1653 /* New queue, no concurrency on queue_flags */
1654 if (!shost
->use_clustering
)
1655 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER
, q
);
1658 * set a reasonable default alignment on word boundaries: the
1659 * host and device may alter it using
1660 * blk_queue_update_dma_alignment() later.
1662 blk_queue_dma_alignment(q
, 0x03);
1666 EXPORT_SYMBOL(__scsi_alloc_queue
);
1668 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1670 struct request_queue
*q
;
1672 q
= __scsi_alloc_queue(sdev
->host
, scsi_request_fn
);
1676 blk_queue_prep_rq(q
, scsi_prep_fn
);
1677 blk_queue_softirq_done(q
, scsi_softirq_done
);
1681 void scsi_free_queue(struct request_queue
*q
)
1683 blk_cleanup_queue(q
);
1687 * Function: scsi_block_requests()
1689 * Purpose: Utility function used by low-level drivers to prevent further
1690 * commands from being queued to the device.
1692 * Arguments: shost - Host in question
1696 * Lock status: No locks are assumed held.
1698 * Notes: There is no timer nor any other means by which the requests
1699 * get unblocked other than the low-level driver calling
1700 * scsi_unblock_requests().
1702 void scsi_block_requests(struct Scsi_Host
*shost
)
1704 shost
->host_self_blocked
= 1;
1706 EXPORT_SYMBOL(scsi_block_requests
);
1709 * Function: scsi_unblock_requests()
1711 * Purpose: Utility function used by low-level drivers to allow further
1712 * commands from being queued to the device.
1714 * Arguments: shost - Host in question
1718 * Lock status: No locks are assumed held.
1720 * Notes: There is no timer nor any other means by which the requests
1721 * get unblocked other than the low-level driver calling
1722 * scsi_unblock_requests().
1724 * This is done as an API function so that changes to the
1725 * internals of the scsi mid-layer won't require wholesale
1726 * changes to drivers that use this feature.
1728 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1730 shost
->host_self_blocked
= 0;
1731 scsi_run_host_queues(shost
);
1733 EXPORT_SYMBOL(scsi_unblock_requests
);
1735 int __init
scsi_init_queue(void)
1739 scsi_io_context_cache
= kmem_cache_create("scsi_io_context",
1740 sizeof(struct scsi_io_context
),
1742 if (!scsi_io_context_cache
) {
1743 printk(KERN_ERR
"SCSI: can't init scsi io context cache\n");
1747 scsi_sdb_cache
= kmem_cache_create("scsi_data_buffer",
1748 sizeof(struct scsi_data_buffer
),
1750 if (!scsi_sdb_cache
) {
1751 printk(KERN_ERR
"SCSI: can't init scsi sdb cache\n");
1752 goto cleanup_io_context
;
1755 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1756 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1757 int size
= sgp
->size
* sizeof(struct scatterlist
);
1759 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1760 SLAB_HWCACHE_ALIGN
, NULL
);
1762 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1767 sgp
->pool
= mempool_create_slab_pool(SG_MEMPOOL_SIZE
,
1770 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1779 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1780 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1782 mempool_destroy(sgp
->pool
);
1784 kmem_cache_destroy(sgp
->slab
);
1786 kmem_cache_destroy(scsi_sdb_cache
);
1788 kmem_cache_destroy(scsi_io_context_cache
);
1793 void scsi_exit_queue(void)
1797 kmem_cache_destroy(scsi_io_context_cache
);
1798 kmem_cache_destroy(scsi_sdb_cache
);
1800 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1801 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1802 mempool_destroy(sgp
->pool
);
1803 kmem_cache_destroy(sgp
->slab
);
1808 * scsi_mode_select - issue a mode select
1809 * @sdev: SCSI device to be queried
1810 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1811 * @sp: Save page bit (0 == don't save, 1 == save)
1812 * @modepage: mode page being requested
1813 * @buffer: request buffer (may not be smaller than eight bytes)
1814 * @len: length of request buffer.
1815 * @timeout: command timeout
1816 * @retries: number of retries before failing
1817 * @data: returns a structure abstracting the mode header data
1818 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1819 * must be SCSI_SENSE_BUFFERSIZE big.
1821 * Returns zero if successful; negative error number or scsi
1826 scsi_mode_select(struct scsi_device
*sdev
, int pf
, int sp
, int modepage
,
1827 unsigned char *buffer
, int len
, int timeout
, int retries
,
1828 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
)
1830 unsigned char cmd
[10];
1831 unsigned char *real_buffer
;
1834 memset(cmd
, 0, sizeof(cmd
));
1835 cmd
[1] = (pf
? 0x10 : 0) | (sp
? 0x01 : 0);
1837 if (sdev
->use_10_for_ms
) {
1840 real_buffer
= kmalloc(8 + len
, GFP_KERNEL
);
1843 memcpy(real_buffer
+ 8, buffer
, len
);
1847 real_buffer
[2] = data
->medium_type
;
1848 real_buffer
[3] = data
->device_specific
;
1849 real_buffer
[4] = data
->longlba
? 0x01 : 0;
1851 real_buffer
[6] = data
->block_descriptor_length
>> 8;
1852 real_buffer
[7] = data
->block_descriptor_length
;
1854 cmd
[0] = MODE_SELECT_10
;
1858 if (len
> 255 || data
->block_descriptor_length
> 255 ||
1862 real_buffer
= kmalloc(4 + len
, GFP_KERNEL
);
1865 memcpy(real_buffer
+ 4, buffer
, len
);
1868 real_buffer
[1] = data
->medium_type
;
1869 real_buffer
[2] = data
->device_specific
;
1870 real_buffer
[3] = data
->block_descriptor_length
;
1873 cmd
[0] = MODE_SELECT
;
1877 ret
= scsi_execute_req(sdev
, cmd
, DMA_TO_DEVICE
, real_buffer
, len
,
1878 sshdr
, timeout
, retries
);
1882 EXPORT_SYMBOL_GPL(scsi_mode_select
);
1885 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1886 * @sdev: SCSI device to be queried
1887 * @dbd: set if mode sense will allow block descriptors to be returned
1888 * @modepage: mode page being requested
1889 * @buffer: request buffer (may not be smaller than eight bytes)
1890 * @len: length of request buffer.
1891 * @timeout: command timeout
1892 * @retries: number of retries before failing
1893 * @data: returns a structure abstracting the mode header data
1894 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1895 * must be SCSI_SENSE_BUFFERSIZE big.
1897 * Returns zero if unsuccessful, or the header offset (either 4
1898 * or 8 depending on whether a six or ten byte command was
1899 * issued) if successful.
1902 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
1903 unsigned char *buffer
, int len
, int timeout
, int retries
,
1904 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
)
1906 unsigned char cmd
[12];
1910 struct scsi_sense_hdr my_sshdr
;
1912 memset(data
, 0, sizeof(*data
));
1913 memset(&cmd
[0], 0, 12);
1914 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
1917 /* caller might not be interested in sense, but we need it */
1922 use_10_for_ms
= sdev
->use_10_for_ms
;
1924 if (use_10_for_ms
) {
1928 cmd
[0] = MODE_SENSE_10
;
1935 cmd
[0] = MODE_SENSE
;
1940 memset(buffer
, 0, len
);
1942 result
= scsi_execute_req(sdev
, cmd
, DMA_FROM_DEVICE
, buffer
, len
,
1943 sshdr
, timeout
, retries
);
1945 /* This code looks awful: what it's doing is making sure an
1946 * ILLEGAL REQUEST sense return identifies the actual command
1947 * byte as the problem. MODE_SENSE commands can return
1948 * ILLEGAL REQUEST if the code page isn't supported */
1950 if (use_10_for_ms
&& !scsi_status_is_good(result
) &&
1951 (driver_byte(result
) & DRIVER_SENSE
)) {
1952 if (scsi_sense_valid(sshdr
)) {
1953 if ((sshdr
->sense_key
== ILLEGAL_REQUEST
) &&
1954 (sshdr
->asc
== 0x20) && (sshdr
->ascq
== 0)) {
1956 * Invalid command operation code
1958 sdev
->use_10_for_ms
= 0;
1964 if(scsi_status_is_good(result
)) {
1965 if (unlikely(buffer
[0] == 0x86 && buffer
[1] == 0x0b &&
1966 (modepage
== 6 || modepage
== 8))) {
1967 /* Initio breakage? */
1970 data
->medium_type
= 0;
1971 data
->device_specific
= 0;
1973 data
->block_descriptor_length
= 0;
1974 } else if(use_10_for_ms
) {
1975 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
1976 data
->medium_type
= buffer
[2];
1977 data
->device_specific
= buffer
[3];
1978 data
->longlba
= buffer
[4] & 0x01;
1979 data
->block_descriptor_length
= buffer
[6]*256
1982 data
->length
= buffer
[0] + 1;
1983 data
->medium_type
= buffer
[1];
1984 data
->device_specific
= buffer
[2];
1985 data
->block_descriptor_length
= buffer
[3];
1987 data
->header_length
= header_length
;
1992 EXPORT_SYMBOL(scsi_mode_sense
);
1995 * scsi_test_unit_ready - test if unit is ready
1996 * @sdev: scsi device to change the state of.
1997 * @timeout: command timeout
1998 * @retries: number of retries before failing
1999 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2000 * returning sense. Make sure that this is cleared before passing
2003 * Returns zero if unsuccessful or an error if TUR failed. For
2004 * removable media, a return of NOT_READY or UNIT_ATTENTION is
2005 * translated to success, with the ->changed flag updated.
2008 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
,
2009 struct scsi_sense_hdr
*sshdr_external
)
2012 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
2014 struct scsi_sense_hdr
*sshdr
;
2017 if (!sshdr_external
)
2018 sshdr
= kzalloc(sizeof(*sshdr
), GFP_KERNEL
);
2020 sshdr
= sshdr_external
;
2022 /* try to eat the UNIT_ATTENTION if there are enough retries */
2024 result
= scsi_execute_req(sdev
, cmd
, DMA_NONE
, NULL
, 0, sshdr
,
2026 } while ((driver_byte(result
) & DRIVER_SENSE
) &&
2027 sshdr
&& sshdr
->sense_key
== UNIT_ATTENTION
&&
2031 /* could not allocate sense buffer, so can't process it */
2034 if ((driver_byte(result
) & DRIVER_SENSE
) && sdev
->removable
) {
2036 if ((scsi_sense_valid(sshdr
)) &&
2037 ((sshdr
->sense_key
== UNIT_ATTENTION
) ||
2038 (sshdr
->sense_key
== NOT_READY
))) {
2043 if (!sshdr_external
)
2047 EXPORT_SYMBOL(scsi_test_unit_ready
);
2050 * scsi_device_set_state - Take the given device through the device state model.
2051 * @sdev: scsi device to change the state of.
2052 * @state: state to change to.
2054 * Returns zero if unsuccessful or an error if the requested
2055 * transition is illegal.
2058 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
2060 enum scsi_device_state oldstate
= sdev
->sdev_state
;
2062 if (state
== oldstate
)
2067 /* There are no legal states that come back to
2068 * created. This is the manually initialised start
2142 sdev
->sdev_state
= state
;
2146 SCSI_LOG_ERROR_RECOVERY(1,
2147 sdev_printk(KERN_ERR
, sdev
,
2148 "Illegal state transition %s->%s\n",
2149 scsi_device_state_name(oldstate
),
2150 scsi_device_state_name(state
))
2154 EXPORT_SYMBOL(scsi_device_set_state
);
2157 * sdev_evt_emit - emit a single SCSI device uevent
2158 * @sdev: associated SCSI device
2159 * @evt: event to emit
2161 * Send a single uevent (scsi_event) to the associated scsi_device.
2163 static void scsi_evt_emit(struct scsi_device
*sdev
, struct scsi_event
*evt
)
2168 switch (evt
->evt_type
) {
2169 case SDEV_EVT_MEDIA_CHANGE
:
2170 envp
[idx
++] = "SDEV_MEDIA_CHANGE=1";
2180 kobject_uevent_env(&sdev
->sdev_gendev
.kobj
, KOBJ_CHANGE
, envp
);
2184 * sdev_evt_thread - send a uevent for each scsi event
2185 * @work: work struct for scsi_device
2187 * Dispatch queued events to their associated scsi_device kobjects
2190 void scsi_evt_thread(struct work_struct
*work
)
2192 struct scsi_device
*sdev
;
2193 LIST_HEAD(event_list
);
2195 sdev
= container_of(work
, struct scsi_device
, event_work
);
2198 struct scsi_event
*evt
;
2199 struct list_head
*this, *tmp
;
2200 unsigned long flags
;
2202 spin_lock_irqsave(&sdev
->list_lock
, flags
);
2203 list_splice_init(&sdev
->event_list
, &event_list
);
2204 spin_unlock_irqrestore(&sdev
->list_lock
, flags
);
2206 if (list_empty(&event_list
))
2209 list_for_each_safe(this, tmp
, &event_list
) {
2210 evt
= list_entry(this, struct scsi_event
, node
);
2211 list_del(&evt
->node
);
2212 scsi_evt_emit(sdev
, evt
);
2219 * sdev_evt_send - send asserted event to uevent thread
2220 * @sdev: scsi_device event occurred on
2221 * @evt: event to send
2223 * Assert scsi device event asynchronously.
2225 void sdev_evt_send(struct scsi_device
*sdev
, struct scsi_event
*evt
)
2227 unsigned long flags
;
2230 /* FIXME: currently this check eliminates all media change events
2231 * for polled devices. Need to update to discriminate between AN
2232 * and polled events */
2233 if (!test_bit(evt
->evt_type
, sdev
->supported_events
)) {
2239 spin_lock_irqsave(&sdev
->list_lock
, flags
);
2240 list_add_tail(&evt
->node
, &sdev
->event_list
);
2241 schedule_work(&sdev
->event_work
);
2242 spin_unlock_irqrestore(&sdev
->list_lock
, flags
);
2244 EXPORT_SYMBOL_GPL(sdev_evt_send
);
2247 * sdev_evt_alloc - allocate a new scsi event
2248 * @evt_type: type of event to allocate
2249 * @gfpflags: GFP flags for allocation
2251 * Allocates and returns a new scsi_event.
2253 struct scsi_event
*sdev_evt_alloc(enum scsi_device_event evt_type
,
2256 struct scsi_event
*evt
= kzalloc(sizeof(struct scsi_event
), gfpflags
);
2260 evt
->evt_type
= evt_type
;
2261 INIT_LIST_HEAD(&evt
->node
);
2263 /* evt_type-specific initialization, if any */
2265 case SDEV_EVT_MEDIA_CHANGE
:
2273 EXPORT_SYMBOL_GPL(sdev_evt_alloc
);
2276 * sdev_evt_send_simple - send asserted event to uevent thread
2277 * @sdev: scsi_device event occurred on
2278 * @evt_type: type of event to send
2279 * @gfpflags: GFP flags for allocation
2281 * Assert scsi device event asynchronously, given an event type.
2283 void sdev_evt_send_simple(struct scsi_device
*sdev
,
2284 enum scsi_device_event evt_type
, gfp_t gfpflags
)
2286 struct scsi_event
*evt
= sdev_evt_alloc(evt_type
, gfpflags
);
2288 sdev_printk(KERN_ERR
, sdev
, "event %d eaten due to OOM\n",
2293 sdev_evt_send(sdev
, evt
);
2295 EXPORT_SYMBOL_GPL(sdev_evt_send_simple
);
2298 * scsi_device_quiesce - Block user issued commands.
2299 * @sdev: scsi device to quiesce.
2301 * This works by trying to transition to the SDEV_QUIESCE state
2302 * (which must be a legal transition). When the device is in this
2303 * state, only special requests will be accepted, all others will
2304 * be deferred. Since special requests may also be requeued requests,
2305 * a successful return doesn't guarantee the device will be
2306 * totally quiescent.
2308 * Must be called with user context, may sleep.
2310 * Returns zero if unsuccessful or an error if not.
2313 scsi_device_quiesce(struct scsi_device
*sdev
)
2315 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
2319 scsi_run_queue(sdev
->request_queue
);
2320 while (sdev
->device_busy
) {
2321 msleep_interruptible(200);
2322 scsi_run_queue(sdev
->request_queue
);
2326 EXPORT_SYMBOL(scsi_device_quiesce
);
2329 * scsi_device_resume - Restart user issued commands to a quiesced device.
2330 * @sdev: scsi device to resume.
2332 * Moves the device from quiesced back to running and restarts the
2335 * Must be called with user context, may sleep.
2338 scsi_device_resume(struct scsi_device
*sdev
)
2340 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
2342 scsi_run_queue(sdev
->request_queue
);
2344 EXPORT_SYMBOL(scsi_device_resume
);
2347 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
2349 scsi_device_quiesce(sdev
);
2353 scsi_target_quiesce(struct scsi_target
*starget
)
2355 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
2357 EXPORT_SYMBOL(scsi_target_quiesce
);
2360 device_resume_fn(struct scsi_device
*sdev
, void *data
)
2362 scsi_device_resume(sdev
);
2366 scsi_target_resume(struct scsi_target
*starget
)
2368 starget_for_each_device(starget
, NULL
, device_resume_fn
);
2370 EXPORT_SYMBOL(scsi_target_resume
);
2373 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2374 * @sdev: device to block
2376 * Block request made by scsi lld's to temporarily stop all
2377 * scsi commands on the specified device. Called from interrupt
2378 * or normal process context.
2380 * Returns zero if successful or error if not
2383 * This routine transitions the device to the SDEV_BLOCK state
2384 * (which must be a legal transition). When the device is in this
2385 * state, all commands are deferred until the scsi lld reenables
2386 * the device with scsi_device_unblock or device_block_tmo fires.
2387 * This routine assumes the host_lock is held on entry.
2390 scsi_internal_device_block(struct scsi_device
*sdev
)
2392 struct request_queue
*q
= sdev
->request_queue
;
2393 unsigned long flags
;
2396 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
2401 * The device has transitioned to SDEV_BLOCK. Stop the
2402 * block layer from calling the midlayer with this device's
2405 spin_lock_irqsave(q
->queue_lock
, flags
);
2407 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2411 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
2414 * scsi_internal_device_unblock - resume a device after a block request
2415 * @sdev: device to resume
2417 * Called by scsi lld's or the midlayer to restart the device queue
2418 * for the previously suspended scsi device. Called from interrupt or
2419 * normal process context.
2421 * Returns zero if successful or error if not.
2424 * This routine transitions the device to the SDEV_RUNNING state
2425 * (which must be a legal transition) allowing the midlayer to
2426 * goose the queue for this device. This routine assumes the
2427 * host_lock is held upon entry.
2430 scsi_internal_device_unblock(struct scsi_device
*sdev
)
2432 struct request_queue
*q
= sdev
->request_queue
;
2434 unsigned long flags
;
2437 * Try to transition the scsi device to SDEV_RUNNING
2438 * and goose the device queue if successful.
2440 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
2444 spin_lock_irqsave(q
->queue_lock
, flags
);
2446 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2450 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
2453 device_block(struct scsi_device
*sdev
, void *data
)
2455 scsi_internal_device_block(sdev
);
2459 target_block(struct device
*dev
, void *data
)
2461 if (scsi_is_target_device(dev
))
2462 starget_for_each_device(to_scsi_target(dev
), NULL
,
2468 scsi_target_block(struct device
*dev
)
2470 if (scsi_is_target_device(dev
))
2471 starget_for_each_device(to_scsi_target(dev
), NULL
,
2474 device_for_each_child(dev
, NULL
, target_block
);
2476 EXPORT_SYMBOL_GPL(scsi_target_block
);
2479 device_unblock(struct scsi_device
*sdev
, void *data
)
2481 scsi_internal_device_unblock(sdev
);
2485 target_unblock(struct device
*dev
, void *data
)
2487 if (scsi_is_target_device(dev
))
2488 starget_for_each_device(to_scsi_target(dev
), NULL
,
2494 scsi_target_unblock(struct device
*dev
)
2496 if (scsi_is_target_device(dev
))
2497 starget_for_each_device(to_scsi_target(dev
), NULL
,
2500 device_for_each_child(dev
, NULL
, target_unblock
);
2502 EXPORT_SYMBOL_GPL(scsi_target_unblock
);
2505 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2506 * @sgl: scatter-gather list
2507 * @sg_count: number of segments in sg
2508 * @offset: offset in bytes into sg, on return offset into the mapped area
2509 * @len: bytes to map, on return number of bytes mapped
2511 * Returns virtual address of the start of the mapped page
2513 void *scsi_kmap_atomic_sg(struct scatterlist
*sgl
, int sg_count
,
2514 size_t *offset
, size_t *len
)
2517 size_t sg_len
= 0, len_complete
= 0;
2518 struct scatterlist
*sg
;
2521 WARN_ON(!irqs_disabled());
2523 for_each_sg(sgl
, sg
, sg_count
, i
) {
2524 len_complete
= sg_len
; /* Complete sg-entries */
2525 sg_len
+= sg
->length
;
2526 if (sg_len
> *offset
)
2530 if (unlikely(i
== sg_count
)) {
2531 printk(KERN_ERR
"%s: Bytes in sg: %zu, requested offset %zu, "
2533 __func__
, sg_len
, *offset
, sg_count
);
2538 /* Offset starting from the beginning of first page in this sg-entry */
2539 *offset
= *offset
- len_complete
+ sg
->offset
;
2541 /* Assumption: contiguous pages can be accessed as "page + i" */
2542 page
= nth_page(sg_page(sg
), (*offset
>> PAGE_SHIFT
));
2543 *offset
&= ~PAGE_MASK
;
2545 /* Bytes in this sg-entry from *offset to the end of the page */
2546 sg_len
= PAGE_SIZE
- *offset
;
2550 return kmap_atomic(page
, KM_BIO_SRC_IRQ
);
2552 EXPORT_SYMBOL(scsi_kmap_atomic_sg
);
2555 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2556 * @virt: virtual address to be unmapped
2558 void scsi_kunmap_atomic_sg(void *virt
)
2560 kunmap_atomic(virt
, KM_BIO_SRC_IRQ
);
2562 EXPORT_SYMBOL(scsi_kunmap_atomic_sg
);