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 scsi_target
*starget
= scsi_target(device
);
118 struct request_queue
*q
= device
->request_queue
;
122 printk("Inserting command %p into mlqueue\n", cmd
));
125 * Set the appropriate busy bit for the device/host.
127 * If the host/device isn't busy, assume that something actually
128 * completed, and that we should be able to queue a command now.
130 * Note that the prior mid-layer assumption that any host could
131 * always queue at least one command is now broken. The mid-layer
132 * will implement a user specifiable stall (see
133 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
134 * if a command is requeued with no other commands outstanding
135 * either for the device or for the host.
138 case SCSI_MLQUEUE_HOST_BUSY
:
139 host
->host_blocked
= host
->max_host_blocked
;
141 case SCSI_MLQUEUE_DEVICE_BUSY
:
142 device
->device_blocked
= device
->max_device_blocked
;
144 case SCSI_MLQUEUE_TARGET_BUSY
:
145 starget
->target_blocked
= starget
->max_target_blocked
;
150 * Decrement the counters, since these commands are no longer
151 * active on the host/device.
153 scsi_device_unbusy(device
);
156 * Requeue this command. It will go before all other commands
157 * that are already in the queue.
159 * NOTE: there is magic here about the way the queue is plugged if
160 * we have no outstanding commands.
162 * Although we *don't* plug the queue, we call the request
163 * function. The SCSI request function detects the blocked condition
164 * and plugs the queue appropriately.
166 spin_lock_irqsave(q
->queue_lock
, flags
);
167 blk_requeue_request(q
, cmd
->request
);
168 spin_unlock_irqrestore(q
->queue_lock
, flags
);
176 * scsi_execute - insert request and wait for the result
179 * @data_direction: data direction
180 * @buffer: data buffer
181 * @bufflen: len of buffer
182 * @sense: optional sense buffer
183 * @timeout: request timeout in seconds
184 * @retries: number of times to retry request
185 * @flags: or into request flags;
187 * returns the req->errors value which is the scsi_cmnd result
190 int scsi_execute(struct scsi_device
*sdev
, const unsigned char *cmd
,
191 int data_direction
, void *buffer
, unsigned bufflen
,
192 unsigned char *sense
, int timeout
, int retries
, int flags
)
195 int write
= (data_direction
== DMA_TO_DEVICE
);
196 int ret
= DRIVER_ERROR
<< 24;
198 req
= blk_get_request(sdev
->request_queue
, write
, __GFP_WAIT
);
200 if (bufflen
&& blk_rq_map_kern(sdev
->request_queue
, req
,
201 buffer
, bufflen
, __GFP_WAIT
))
204 req
->cmd_len
= COMMAND_SIZE(cmd
[0]);
205 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
208 req
->retries
= retries
;
209 req
->timeout
= timeout
;
210 req
->cmd_type
= REQ_TYPE_BLOCK_PC
;
211 req
->cmd_flags
|= flags
| REQ_QUIET
| REQ_PREEMPT
;
214 * head injection *required* here otherwise quiesce won't work
216 blk_execute_rq(req
->q
, NULL
, req
, 1);
219 * Some devices (USB mass-storage in particular) may transfer
220 * garbage data together with a residue indicating that the data
221 * is invalid. Prevent the garbage from being misinterpreted
222 * and prevent security leaks by zeroing out the excess data.
224 if (unlikely(req
->data_len
> 0 && req
->data_len
<= bufflen
))
225 memset(buffer
+ (bufflen
- req
->data_len
), 0, req
->data_len
);
229 blk_put_request(req
);
233 EXPORT_SYMBOL(scsi_execute
);
236 int scsi_execute_req(struct scsi_device
*sdev
, const unsigned char *cmd
,
237 int data_direction
, void *buffer
, unsigned bufflen
,
238 struct scsi_sense_hdr
*sshdr
, int timeout
, int retries
)
244 sense
= kzalloc(SCSI_SENSE_BUFFERSIZE
, GFP_NOIO
);
246 return DRIVER_ERROR
<< 24;
248 result
= scsi_execute(sdev
, cmd
, data_direction
, buffer
, bufflen
,
249 sense
, timeout
, retries
, 0);
251 scsi_normalize_sense(sense
, SCSI_SENSE_BUFFERSIZE
, sshdr
);
256 EXPORT_SYMBOL(scsi_execute_req
);
258 struct scsi_io_context
{
260 void (*done
)(void *data
, char *sense
, int result
, int resid
);
261 char sense
[SCSI_SENSE_BUFFERSIZE
];
264 static struct kmem_cache
*scsi_io_context_cache
;
266 static void scsi_end_async(struct request
*req
, int uptodate
)
268 struct scsi_io_context
*sioc
= req
->end_io_data
;
271 sioc
->done(sioc
->data
, sioc
->sense
, req
->errors
, req
->data_len
);
273 kmem_cache_free(scsi_io_context_cache
, sioc
);
274 __blk_put_request(req
->q
, req
);
277 static int scsi_merge_bio(struct request
*rq
, struct bio
*bio
)
279 struct request_queue
*q
= rq
->q
;
281 bio
->bi_flags
&= ~(1 << BIO_SEG_VALID
);
282 if (rq_data_dir(rq
) == WRITE
)
283 bio
->bi_rw
|= (1 << BIO_RW
);
284 blk_queue_bounce(q
, &bio
);
286 return blk_rq_append_bio(q
, rq
, bio
);
289 static void scsi_bi_endio(struct bio
*bio
, int error
)
295 * scsi_req_map_sg - map a scatterlist into a request
296 * @rq: request to fill
298 * @nsegs: number of elements
299 * @bufflen: len of buffer
300 * @gfp: memory allocation flags
302 * scsi_req_map_sg maps a scatterlist into a request so that the
303 * request can be sent to the block layer. We do not trust the scatterlist
304 * sent to use, as some ULDs use that struct to only organize the pages.
306 static int scsi_req_map_sg(struct request
*rq
, struct scatterlist
*sgl
,
307 int nsegs
, unsigned bufflen
, gfp_t gfp
)
309 struct request_queue
*q
= rq
->q
;
310 int nr_pages
= (bufflen
+ sgl
[0].offset
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
311 unsigned int data_len
= bufflen
, len
, bytes
, off
;
312 struct scatterlist
*sg
;
314 struct bio
*bio
= NULL
;
315 int i
, err
, nr_vecs
= 0;
317 for_each_sg(sgl
, sg
, nsegs
, i
) {
322 while (len
> 0 && data_len
> 0) {
324 * sg sends a scatterlist that is larger than
325 * the data_len it wants transferred for certain
328 bytes
= min_t(unsigned int, len
, PAGE_SIZE
- off
);
329 bytes
= min(bytes
, data_len
);
332 nr_vecs
= min_t(int, BIO_MAX_PAGES
, nr_pages
);
335 bio
= bio_alloc(gfp
, nr_vecs
);
340 bio
->bi_end_io
= scsi_bi_endio
;
343 if (bio_add_pc_page(q
, bio
, page
, bytes
, off
) !=
350 if (bio
->bi_vcnt
>= nr_vecs
) {
351 err
= scsi_merge_bio(rq
, bio
);
366 rq
->buffer
= rq
->data
= NULL
;
367 rq
->data_len
= bufflen
;
371 while ((bio
= rq
->bio
) != NULL
) {
372 rq
->bio
= bio
->bi_next
;
374 * call endio instead of bio_put incase it was bounced
383 * scsi_execute_async - insert request
386 * @cmd_len: length of scsi cdb
387 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
388 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
389 * @bufflen: len of buffer
390 * @use_sg: if buffer is a scatterlist this is the number of elements
391 * @timeout: request timeout in seconds
392 * @retries: number of times to retry request
393 * @privdata: data passed to done()
394 * @done: callback function when done
395 * @gfp: memory allocation flags
397 int scsi_execute_async(struct scsi_device
*sdev
, const unsigned char *cmd
,
398 int cmd_len
, int data_direction
, void *buffer
, unsigned bufflen
,
399 int use_sg
, int timeout
, int retries
, void *privdata
,
400 void (*done
)(void *, char *, int, int), gfp_t gfp
)
403 struct scsi_io_context
*sioc
;
405 int write
= (data_direction
== DMA_TO_DEVICE
);
407 sioc
= kmem_cache_zalloc(scsi_io_context_cache
, gfp
);
409 return DRIVER_ERROR
<< 24;
411 req
= blk_get_request(sdev
->request_queue
, write
, gfp
);
414 req
->cmd_type
= REQ_TYPE_BLOCK_PC
;
415 req
->cmd_flags
|= REQ_QUIET
;
418 err
= scsi_req_map_sg(req
, buffer
, use_sg
, bufflen
, gfp
);
420 err
= blk_rq_map_kern(req
->q
, req
, buffer
, bufflen
, gfp
);
425 req
->cmd_len
= cmd_len
;
426 memset(req
->cmd
, 0, BLK_MAX_CDB
); /* ATAPI hates garbage after CDB */
427 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
428 req
->sense
= sioc
->sense
;
430 req
->timeout
= timeout
;
431 req
->retries
= retries
;
432 req
->end_io_data
= sioc
;
434 sioc
->data
= privdata
;
437 blk_execute_rq_nowait(req
->q
, NULL
, req
, 1, scsi_end_async
);
441 blk_put_request(req
);
443 kmem_cache_free(scsi_io_context_cache
, sioc
);
444 return DRIVER_ERROR
<< 24;
446 EXPORT_SYMBOL_GPL(scsi_execute_async
);
449 * Function: scsi_init_cmd_errh()
451 * Purpose: Initialize cmd fields related to error handling.
453 * Arguments: cmd - command that is ready to be queued.
455 * Notes: This function has the job of initializing a number of
456 * fields related to error handling. Typically this will
457 * be called once for each command, as required.
459 static void scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
461 cmd
->serial_number
= 0;
462 scsi_set_resid(cmd
, 0);
463 memset(cmd
->sense_buffer
, 0, SCSI_SENSE_BUFFERSIZE
);
464 if (cmd
->cmd_len
== 0)
465 cmd
->cmd_len
= scsi_command_size(cmd
->cmnd
);
468 void scsi_device_unbusy(struct scsi_device
*sdev
)
470 struct Scsi_Host
*shost
= sdev
->host
;
471 struct scsi_target
*starget
= scsi_target(sdev
);
474 spin_lock_irqsave(shost
->host_lock
, flags
);
476 starget
->target_busy
--;
477 if (unlikely(scsi_host_in_recovery(shost
) &&
478 (shost
->host_failed
|| shost
->host_eh_scheduled
)))
479 scsi_eh_wakeup(shost
);
480 spin_unlock(shost
->host_lock
);
481 spin_lock(sdev
->request_queue
->queue_lock
);
483 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
487 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
488 * and call blk_run_queue for all the scsi_devices on the target -
489 * including current_sdev first.
491 * Called with *no* scsi locks held.
493 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
495 struct Scsi_Host
*shost
= current_sdev
->host
;
496 struct scsi_device
*sdev
, *tmp
;
497 struct scsi_target
*starget
= scsi_target(current_sdev
);
500 spin_lock_irqsave(shost
->host_lock
, flags
);
501 starget
->starget_sdev_user
= NULL
;
502 spin_unlock_irqrestore(shost
->host_lock
, flags
);
505 * Call blk_run_queue for all LUNs on the target, starting with
506 * current_sdev. We race with others (to set starget_sdev_user),
507 * but in most cases, we will be first. Ideally, each LU on the
508 * target would get some limited time or requests on the target.
510 blk_run_queue(current_sdev
->request_queue
);
512 spin_lock_irqsave(shost
->host_lock
, flags
);
513 if (starget
->starget_sdev_user
)
515 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
516 same_target_siblings
) {
517 if (sdev
== current_sdev
)
519 if (scsi_device_get(sdev
))
522 spin_unlock_irqrestore(shost
->host_lock
, flags
);
523 blk_run_queue(sdev
->request_queue
);
524 spin_lock_irqsave(shost
->host_lock
, flags
);
526 scsi_device_put(sdev
);
529 spin_unlock_irqrestore(shost
->host_lock
, flags
);
532 static inline int scsi_target_is_busy(struct scsi_target
*starget
)
534 return ((starget
->can_queue
> 0 &&
535 starget
->target_busy
>= starget
->can_queue
) ||
536 starget
->target_blocked
);
540 * Function: scsi_run_queue()
542 * Purpose: Select a proper request queue to serve next
544 * Arguments: q - last request's queue
548 * Notes: The previous command was completely finished, start
549 * a new one if possible.
551 static void scsi_run_queue(struct request_queue
*q
)
553 struct scsi_device
*starved_head
= NULL
, *sdev
= q
->queuedata
;
554 struct Scsi_Host
*shost
= sdev
->host
;
557 if (scsi_target(sdev
)->single_lun
)
558 scsi_single_lun_run(sdev
);
560 spin_lock_irqsave(shost
->host_lock
, flags
);
561 while (!list_empty(&shost
->starved_list
) &&
562 !shost
->host_blocked
&& !shost
->host_self_blocked
&&
563 !((shost
->can_queue
> 0) &&
564 (shost
->host_busy
>= shost
->can_queue
))) {
569 * As long as shost is accepting commands and we have
570 * starved queues, call blk_run_queue. scsi_request_fn
571 * drops the queue_lock and can add us back to the
574 * host_lock protects the starved_list and starved_entry.
575 * scsi_request_fn must get the host_lock before checking
576 * or modifying starved_list or starved_entry.
578 sdev
= list_entry(shost
->starved_list
.next
,
579 struct scsi_device
, starved_entry
);
581 * The *queue_ready functions can add a device back onto the
582 * starved list's tail, so we must check for a infinite loop.
584 if (sdev
== starved_head
)
589 if (scsi_target_is_busy(scsi_target(sdev
))) {
590 list_move_tail(&sdev
->starved_entry
,
591 &shost
->starved_list
);
595 list_del_init(&sdev
->starved_entry
);
596 spin_unlock(shost
->host_lock
);
598 spin_lock(sdev
->request_queue
->queue_lock
);
599 flagset
= test_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
) &&
600 !test_bit(QUEUE_FLAG_REENTER
,
601 &sdev
->request_queue
->queue_flags
);
603 queue_flag_set(QUEUE_FLAG_REENTER
, sdev
->request_queue
);
604 __blk_run_queue(sdev
->request_queue
);
606 queue_flag_clear(QUEUE_FLAG_REENTER
, sdev
->request_queue
);
607 spin_unlock(sdev
->request_queue
->queue_lock
);
609 spin_lock(shost
->host_lock
);
611 spin_unlock_irqrestore(shost
->host_lock
, flags
);
617 * Function: scsi_requeue_command()
619 * Purpose: Handle post-processing of completed commands.
621 * Arguments: q - queue to operate on
622 * cmd - command that may need to be requeued.
626 * Notes: After command completion, there may be blocks left
627 * over which weren't finished by the previous command
628 * this can be for a number of reasons - the main one is
629 * I/O errors in the middle of the request, in which case
630 * we need to request the blocks that come after the bad
632 * Notes: Upon return, cmd is a stale pointer.
634 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
636 struct request
*req
= cmd
->request
;
639 scsi_unprep_request(req
);
640 spin_lock_irqsave(q
->queue_lock
, flags
);
641 blk_requeue_request(q
, req
);
642 spin_unlock_irqrestore(q
->queue_lock
, flags
);
647 void scsi_next_command(struct scsi_cmnd
*cmd
)
649 struct scsi_device
*sdev
= cmd
->device
;
650 struct request_queue
*q
= sdev
->request_queue
;
652 /* need to hold a reference on the device before we let go of the cmd */
653 get_device(&sdev
->sdev_gendev
);
655 scsi_put_command(cmd
);
658 /* ok to remove device now */
659 put_device(&sdev
->sdev_gendev
);
662 void scsi_run_host_queues(struct Scsi_Host
*shost
)
664 struct scsi_device
*sdev
;
666 shost_for_each_device(sdev
, shost
)
667 scsi_run_queue(sdev
->request_queue
);
671 * Function: scsi_end_request()
673 * Purpose: Post-processing of completed commands (usually invoked at end
674 * of upper level post-processing and scsi_io_completion).
676 * Arguments: cmd - command that is complete.
677 * error - 0 if I/O indicates success, < 0 for I/O error.
678 * bytes - number of bytes of completed I/O
679 * requeue - indicates whether we should requeue leftovers.
681 * Lock status: Assumed that lock is not held upon entry.
683 * Returns: cmd if requeue required, NULL otherwise.
685 * Notes: This is called for block device requests in order to
686 * mark some number of sectors as complete.
688 * We are guaranteeing that the request queue will be goosed
689 * at some point during this call.
690 * Notes: If cmd was requeued, upon return it will be a stale pointer.
692 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int error
,
693 int bytes
, int requeue
)
695 struct request_queue
*q
= cmd
->device
->request_queue
;
696 struct request
*req
= cmd
->request
;
699 * If there are blocks left over at the end, set up the command
700 * to queue the remainder of them.
702 if (blk_end_request(req
, error
, bytes
)) {
703 int leftover
= (req
->hard_nr_sectors
<< 9);
705 if (blk_pc_request(req
))
706 leftover
= req
->data_len
;
708 /* kill remainder if no retrys */
709 if (error
&& scsi_noretry_cmd(cmd
))
710 blk_end_request(req
, error
, leftover
);
714 * Bleah. Leftovers again. Stick the
715 * leftovers in the front of the
716 * queue, and goose the queue again.
718 scsi_requeue_command(q
, cmd
);
726 * This will goose the queue request function at the end, so we don't
727 * need to worry about launching another command.
729 scsi_next_command(cmd
);
733 static inline unsigned int scsi_sgtable_index(unsigned short nents
)
737 BUG_ON(nents
> SCSI_MAX_SG_SEGMENTS
);
742 index
= get_count_order(nents
) - 3;
747 static void scsi_sg_free(struct scatterlist
*sgl
, unsigned int nents
)
749 struct scsi_host_sg_pool
*sgp
;
751 sgp
= scsi_sg_pools
+ scsi_sgtable_index(nents
);
752 mempool_free(sgl
, sgp
->pool
);
755 static struct scatterlist
*scsi_sg_alloc(unsigned int nents
, gfp_t gfp_mask
)
757 struct scsi_host_sg_pool
*sgp
;
759 sgp
= scsi_sg_pools
+ scsi_sgtable_index(nents
);
760 return mempool_alloc(sgp
->pool
, gfp_mask
);
763 static int scsi_alloc_sgtable(struct scsi_data_buffer
*sdb
, int nents
,
770 ret
= __sg_alloc_table(&sdb
->table
, nents
, SCSI_MAX_SG_SEGMENTS
,
771 gfp_mask
, scsi_sg_alloc
);
773 __sg_free_table(&sdb
->table
, SCSI_MAX_SG_SEGMENTS
,
779 static void scsi_free_sgtable(struct scsi_data_buffer
*sdb
)
781 __sg_free_table(&sdb
->table
, SCSI_MAX_SG_SEGMENTS
, scsi_sg_free
);
785 * Function: scsi_release_buffers()
787 * Purpose: Completion processing for block device I/O requests.
789 * Arguments: cmd - command that we are bailing.
791 * Lock status: Assumed that no lock is held upon entry.
795 * Notes: In the event that an upper level driver rejects a
796 * command, we must release resources allocated during
797 * the __init_io() function. Primarily this would involve
798 * the scatter-gather table, and potentially any bounce
801 void scsi_release_buffers(struct scsi_cmnd
*cmd
)
803 if (cmd
->sdb
.table
.nents
)
804 scsi_free_sgtable(&cmd
->sdb
);
806 memset(&cmd
->sdb
, 0, sizeof(cmd
->sdb
));
808 if (scsi_bidi_cmnd(cmd
)) {
809 struct scsi_data_buffer
*bidi_sdb
=
810 cmd
->request
->next_rq
->special
;
811 scsi_free_sgtable(bidi_sdb
);
812 kmem_cache_free(scsi_sdb_cache
, bidi_sdb
);
813 cmd
->request
->next_rq
->special
= NULL
;
816 if (scsi_prot_sg_count(cmd
))
817 scsi_free_sgtable(cmd
->prot_sdb
);
819 EXPORT_SYMBOL(scsi_release_buffers
);
822 * Bidi commands Must be complete as a whole, both sides at once.
823 * If part of the bytes were written and lld returned
824 * scsi_in()->resid and/or scsi_out()->resid this information will be left
825 * in req->data_len and req->next_rq->data_len. The upper-layer driver can
826 * decide what to do with this information.
828 static void scsi_end_bidi_request(struct scsi_cmnd
*cmd
)
830 struct request
*req
= cmd
->request
;
831 unsigned int dlen
= req
->data_len
;
832 unsigned int next_dlen
= req
->next_rq
->data_len
;
834 req
->data_len
= scsi_out(cmd
)->resid
;
835 req
->next_rq
->data_len
= scsi_in(cmd
)->resid
;
837 /* The req and req->next_rq have not been completed */
838 BUG_ON(blk_end_bidi_request(req
, 0, dlen
, next_dlen
));
840 scsi_release_buffers(cmd
);
843 * This will goose the queue request function at the end, so we don't
844 * need to worry about launching another command.
846 scsi_next_command(cmd
);
850 * Function: scsi_io_completion()
852 * Purpose: Completion processing for block device I/O requests.
854 * Arguments: cmd - command that is finished.
856 * Lock status: Assumed that no lock is held upon entry.
860 * Notes: This function is matched in terms of capabilities to
861 * the function that created the scatter-gather list.
862 * In other words, if there are no bounce buffers
863 * (the normal case for most drivers), we don't need
864 * the logic to deal with cleaning up afterwards.
866 * We must do one of several things here:
868 * a) Call scsi_end_request. This will finish off the
869 * specified number of sectors. If we are done, the
870 * command block will be released, and the queue
871 * function will be goosed. If we are not done, then
872 * scsi_end_request will directly goose the queue.
874 * b) We can just use scsi_requeue_command() here. This would
875 * be used if we just wanted to retry, for example.
877 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
)
879 int result
= cmd
->result
;
881 struct request_queue
*q
= cmd
->device
->request_queue
;
882 struct request
*req
= cmd
->request
;
884 struct scsi_sense_hdr sshdr
;
886 int sense_deferred
= 0;
889 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
891 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
894 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
895 req
->errors
= result
;
897 if (sense_valid
&& req
->sense
) {
899 * SG_IO wants current and deferred errors
901 int len
= 8 + cmd
->sense_buffer
[7];
903 if (len
> SCSI_SENSE_BUFFERSIZE
)
904 len
= SCSI_SENSE_BUFFERSIZE
;
905 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
906 req
->sense_len
= len
;
911 if (scsi_bidi_cmnd(cmd
)) {
912 /* will also release_buffers */
913 scsi_end_bidi_request(cmd
);
916 req
->data_len
= scsi_get_resid(cmd
);
919 BUG_ON(blk_bidi_rq(req
)); /* bidi not support for !blk_pc_request yet */
920 scsi_release_buffers(cmd
);
923 * Next deal with any sectors which we were able to correctly
926 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
928 req
->nr_sectors
, good_bytes
));
930 /* A number of bytes were successfully read. If there
931 * are leftovers and there is some kind of error
932 * (result != 0), retry the rest.
934 if (scsi_end_request(cmd
, error
, good_bytes
, result
== 0) == NULL
)
936 this_count
= blk_rq_bytes(req
);
938 /* good_bytes = 0, or (inclusive) there were leftovers and
939 * result = 0, so scsi_end_request couldn't retry.
941 if (sense_valid
&& !sense_deferred
) {
942 switch (sshdr
.sense_key
) {
944 if (cmd
->device
->removable
) {
945 /* Detected disc change. Set a bit
946 * and quietly refuse further access.
948 cmd
->device
->changed
= 1;
949 scsi_end_request(cmd
, -EIO
, this_count
, 1);
952 /* Must have been a power glitch, or a
953 * bus reset. Could not have been a
954 * media change, so we just retry the
955 * request and see what happens.
957 scsi_requeue_command(q
, cmd
);
961 case ILLEGAL_REQUEST
:
962 /* If we had an ILLEGAL REQUEST returned, then
963 * we may have performed an unsupported
964 * command. The only thing this should be
965 * would be a ten byte read where only a six
966 * byte read was supported. Also, on a system
967 * where READ CAPACITY failed, we may have
968 * read past the end of the disk.
970 if ((cmd
->device
->use_10_for_rw
&&
971 sshdr
.asc
== 0x20 && sshdr
.ascq
== 0x00) &&
972 (cmd
->cmnd
[0] == READ_10
||
973 cmd
->cmnd
[0] == WRITE_10
)) {
974 cmd
->device
->use_10_for_rw
= 0;
975 /* This will cause a retry with a
978 scsi_requeue_command(q
, cmd
);
979 } else if (sshdr
.asc
== 0x10) /* DIX */
980 scsi_end_request(cmd
, -EIO
, this_count
, 0);
982 scsi_end_request(cmd
, -EIO
, this_count
, 1);
984 case ABORTED_COMMAND
:
985 if (sshdr
.asc
== 0x10) { /* DIF */
986 scsi_end_request(cmd
, -EIO
, this_count
, 0);
991 /* If the device is in the process of becoming
992 * ready, or has a temporary blockage, retry.
994 if (sshdr
.asc
== 0x04) {
995 switch (sshdr
.ascq
) {
996 case 0x01: /* becoming ready */
997 case 0x04: /* format in progress */
998 case 0x05: /* rebuild in progress */
999 case 0x06: /* recalculation in progress */
1000 case 0x07: /* operation in progress */
1001 case 0x08: /* Long write in progress */
1002 case 0x09: /* self test in progress */
1003 scsi_requeue_command(q
, cmd
);
1009 if (!(req
->cmd_flags
& REQ_QUIET
))
1010 scsi_cmd_print_sense_hdr(cmd
,
1014 scsi_end_request(cmd
, -EIO
, this_count
, 1);
1016 case VOLUME_OVERFLOW
:
1017 if (!(req
->cmd_flags
& REQ_QUIET
)) {
1018 scmd_printk(KERN_INFO
, cmd
,
1019 "Volume overflow, CDB: ");
1020 __scsi_print_command(cmd
->cmnd
);
1021 scsi_print_sense("", cmd
);
1023 /* See SSC3rXX or current. */
1024 scsi_end_request(cmd
, -EIO
, this_count
, 1);
1030 if (host_byte(result
) == DID_RESET
) {
1031 /* Third party bus reset or reset for error recovery
1032 * reasons. Just retry the request and see what
1035 scsi_requeue_command(q
, cmd
);
1039 if (!(req
->cmd_flags
& REQ_QUIET
)) {
1040 scsi_print_result(cmd
);
1041 if (driver_byte(result
) & DRIVER_SENSE
)
1042 scsi_print_sense("", cmd
);
1045 scsi_end_request(cmd
, -EIO
, this_count
, !result
);
1048 static int scsi_init_sgtable(struct request
*req
, struct scsi_data_buffer
*sdb
,
1054 * If sg table allocation fails, requeue request later.
1056 if (unlikely(scsi_alloc_sgtable(sdb
, req
->nr_phys_segments
,
1058 return BLKPREP_DEFER
;
1064 * Next, walk the list, and fill in the addresses and sizes of
1067 count
= blk_rq_map_sg(req
->q
, req
, sdb
->table
.sgl
);
1068 BUG_ON(count
> sdb
->table
.nents
);
1069 sdb
->table
.nents
= count
;
1070 if (blk_pc_request(req
))
1071 sdb
->length
= req
->data_len
;
1073 sdb
->length
= req
->nr_sectors
<< 9;
1078 * Function: scsi_init_io()
1080 * Purpose: SCSI I/O initialize function.
1082 * Arguments: cmd - Command descriptor we wish to initialize
1084 * Returns: 0 on success
1085 * BLKPREP_DEFER if the failure is retryable
1086 * BLKPREP_KILL if the failure is fatal
1088 int scsi_init_io(struct scsi_cmnd
*cmd
, gfp_t gfp_mask
)
1090 int error
= scsi_init_sgtable(cmd
->request
, &cmd
->sdb
, gfp_mask
);
1094 if (blk_bidi_rq(cmd
->request
)) {
1095 struct scsi_data_buffer
*bidi_sdb
= kmem_cache_zalloc(
1096 scsi_sdb_cache
, GFP_ATOMIC
);
1098 error
= BLKPREP_DEFER
;
1102 cmd
->request
->next_rq
->special
= bidi_sdb
;
1103 error
= scsi_init_sgtable(cmd
->request
->next_rq
, bidi_sdb
,
1109 if (blk_integrity_rq(cmd
->request
)) {
1110 struct scsi_data_buffer
*prot_sdb
= cmd
->prot_sdb
;
1113 BUG_ON(prot_sdb
== NULL
);
1114 ivecs
= blk_rq_count_integrity_sg(cmd
->request
);
1116 if (scsi_alloc_sgtable(prot_sdb
, ivecs
, gfp_mask
)) {
1117 error
= BLKPREP_DEFER
;
1121 count
= blk_rq_map_integrity_sg(cmd
->request
,
1122 prot_sdb
->table
.sgl
);
1123 BUG_ON(unlikely(count
> ivecs
));
1125 cmd
->prot_sdb
= prot_sdb
;
1126 cmd
->prot_sdb
->table
.nents
= count
;
1132 scsi_release_buffers(cmd
);
1133 if (error
== BLKPREP_KILL
)
1134 scsi_put_command(cmd
);
1135 else /* BLKPREP_DEFER */
1136 scsi_unprep_request(cmd
->request
);
1140 EXPORT_SYMBOL(scsi_init_io
);
1142 static struct scsi_cmnd
*scsi_get_cmd_from_req(struct scsi_device
*sdev
,
1143 struct request
*req
)
1145 struct scsi_cmnd
*cmd
;
1147 if (!req
->special
) {
1148 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1156 /* pull a tag out of the request if we have one */
1157 cmd
->tag
= req
->tag
;
1160 cmd
->cmnd
= req
->cmd
;
1165 int scsi_setup_blk_pc_cmnd(struct scsi_device
*sdev
, struct request
*req
)
1167 struct scsi_cmnd
*cmd
;
1168 int ret
= scsi_prep_state_check(sdev
, req
);
1170 if (ret
!= BLKPREP_OK
)
1173 cmd
= scsi_get_cmd_from_req(sdev
, req
);
1175 return BLKPREP_DEFER
;
1178 * BLOCK_PC requests may transfer data, in which case they must
1179 * a bio attached to them. Or they might contain a SCSI command
1180 * that does not transfer data, in which case they may optionally
1181 * submit a request without an attached bio.
1186 BUG_ON(!req
->nr_phys_segments
);
1188 ret
= scsi_init_io(cmd
, GFP_ATOMIC
);
1192 BUG_ON(req
->data_len
);
1195 memset(&cmd
->sdb
, 0, sizeof(cmd
->sdb
));
1199 cmd
->cmd_len
= req
->cmd_len
;
1201 cmd
->sc_data_direction
= DMA_NONE
;
1202 else if (rq_data_dir(req
) == WRITE
)
1203 cmd
->sc_data_direction
= DMA_TO_DEVICE
;
1205 cmd
->sc_data_direction
= DMA_FROM_DEVICE
;
1207 cmd
->transfersize
= req
->data_len
;
1208 cmd
->allowed
= req
->retries
;
1211 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd
);
1214 * Setup a REQ_TYPE_FS command. These are simple read/write request
1215 * from filesystems that still need to be translated to SCSI CDBs from
1218 int scsi_setup_fs_cmnd(struct scsi_device
*sdev
, struct request
*req
)
1220 struct scsi_cmnd
*cmd
;
1221 int ret
= scsi_prep_state_check(sdev
, req
);
1223 if (ret
!= BLKPREP_OK
)
1226 if (unlikely(sdev
->scsi_dh_data
&& sdev
->scsi_dh_data
->scsi_dh
1227 && sdev
->scsi_dh_data
->scsi_dh
->prep_fn
)) {
1228 ret
= sdev
->scsi_dh_data
->scsi_dh
->prep_fn(sdev
, req
);
1229 if (ret
!= BLKPREP_OK
)
1234 * Filesystem requests must transfer data.
1236 BUG_ON(!req
->nr_phys_segments
);
1238 cmd
= scsi_get_cmd_from_req(sdev
, req
);
1240 return BLKPREP_DEFER
;
1242 memset(cmd
->cmnd
, 0, BLK_MAX_CDB
);
1243 return scsi_init_io(cmd
, GFP_ATOMIC
);
1245 EXPORT_SYMBOL(scsi_setup_fs_cmnd
);
1247 int scsi_prep_state_check(struct scsi_device
*sdev
, struct request
*req
)
1249 int ret
= BLKPREP_OK
;
1252 * If the device is not in running state we will reject some
1255 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1256 switch (sdev
->sdev_state
) {
1259 * If the device is offline we refuse to process any
1260 * commands. The device must be brought online
1261 * before trying any recovery commands.
1263 sdev_printk(KERN_ERR
, sdev
,
1264 "rejecting I/O to offline device\n");
1269 * If the device is fully deleted, we refuse to
1270 * process any commands as well.
1272 sdev_printk(KERN_ERR
, sdev
,
1273 "rejecting I/O to dead device\n");
1278 case SDEV_CREATED_BLOCK
:
1280 * If the devices is blocked we defer normal commands.
1282 if (!(req
->cmd_flags
& REQ_PREEMPT
))
1283 ret
= BLKPREP_DEFER
;
1287 * For any other not fully online state we only allow
1288 * special commands. In particular any user initiated
1289 * command is not allowed.
1291 if (!(req
->cmd_flags
& REQ_PREEMPT
))
1298 EXPORT_SYMBOL(scsi_prep_state_check
);
1300 int scsi_prep_return(struct request_queue
*q
, struct request
*req
, int ret
)
1302 struct scsi_device
*sdev
= q
->queuedata
;
1306 req
->errors
= DID_NO_CONNECT
<< 16;
1307 /* release the command and kill it */
1309 struct scsi_cmnd
*cmd
= req
->special
;
1310 scsi_release_buffers(cmd
);
1311 scsi_put_command(cmd
);
1312 req
->special
= NULL
;
1317 * If we defer, the elv_next_request() returns NULL, but the
1318 * queue must be restarted, so we plug here if no returning
1319 * command will automatically do that.
1321 if (sdev
->device_busy
== 0)
1325 req
->cmd_flags
|= REQ_DONTPREP
;
1330 EXPORT_SYMBOL(scsi_prep_return
);
1332 int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1334 struct scsi_device
*sdev
= q
->queuedata
;
1335 int ret
= BLKPREP_KILL
;
1337 if (req
->cmd_type
== REQ_TYPE_BLOCK_PC
)
1338 ret
= scsi_setup_blk_pc_cmnd(sdev
, req
);
1339 return scsi_prep_return(q
, req
, ret
);
1343 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1346 * Called with the queue_lock held.
1348 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1349 struct scsi_device
*sdev
)
1351 if (sdev
->device_busy
>= sdev
->queue_depth
)
1353 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1355 * unblock after device_blocked iterates to zero
1357 if (--sdev
->device_blocked
== 0) {
1359 sdev_printk(KERN_INFO
, sdev
,
1360 "unblocking device at zero depth\n"));
1366 if (sdev
->device_blocked
)
1374 * scsi_target_queue_ready: checks if there we can send commands to target
1375 * @sdev: scsi device on starget to check.
1377 * Called with the host lock held.
1379 static inline int scsi_target_queue_ready(struct Scsi_Host
*shost
,
1380 struct scsi_device
*sdev
)
1382 struct scsi_target
*starget
= scsi_target(sdev
);
1384 if (starget
->single_lun
) {
1385 if (starget
->starget_sdev_user
&&
1386 starget
->starget_sdev_user
!= sdev
)
1388 starget
->starget_sdev_user
= sdev
;
1391 if (starget
->target_busy
== 0 && starget
->target_blocked
) {
1393 * unblock after target_blocked iterates to zero
1395 if (--starget
->target_blocked
== 0) {
1396 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO
, starget
,
1397 "unblocking target at zero depth\n"));
1399 blk_plug_device(sdev
->request_queue
);
1404 if (scsi_target_is_busy(starget
)) {
1405 if (list_empty(&sdev
->starved_entry
)) {
1406 list_add_tail(&sdev
->starved_entry
,
1407 &shost
->starved_list
);
1412 /* We're OK to process the command, so we can't be starved */
1413 if (!list_empty(&sdev
->starved_entry
))
1414 list_del_init(&sdev
->starved_entry
);
1419 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1420 * return 0. We must end up running the queue again whenever 0 is
1421 * returned, else IO can hang.
1423 * Called with host_lock held.
1425 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1426 struct Scsi_Host
*shost
,
1427 struct scsi_device
*sdev
)
1429 if (scsi_host_in_recovery(shost
))
1431 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1433 * unblock after host_blocked iterates to zero
1435 if (--shost
->host_blocked
== 0) {
1437 printk("scsi%d unblocking host at zero depth\n",
1443 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
1444 shost
->host_blocked
|| shost
->host_self_blocked
) {
1445 if (list_empty(&sdev
->starved_entry
))
1446 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1450 /* We're OK to process the command, so we can't be starved */
1451 if (!list_empty(&sdev
->starved_entry
))
1452 list_del_init(&sdev
->starved_entry
);
1458 * Kill a request for a dead device
1460 static void scsi_kill_request(struct request
*req
, struct request_queue
*q
)
1462 struct scsi_cmnd
*cmd
= req
->special
;
1463 struct scsi_device
*sdev
= cmd
->device
;
1464 struct scsi_target
*starget
= scsi_target(sdev
);
1465 struct Scsi_Host
*shost
= sdev
->host
;
1467 blkdev_dequeue_request(req
);
1469 if (unlikely(cmd
== NULL
)) {
1470 printk(KERN_CRIT
"impossible request in %s.\n",
1475 scsi_init_cmd_errh(cmd
);
1476 cmd
->result
= DID_NO_CONNECT
<< 16;
1477 atomic_inc(&cmd
->device
->iorequest_cnt
);
1480 * SCSI request completion path will do scsi_device_unbusy(),
1481 * bump busy counts. To bump the counters, we need to dance
1482 * with the locks as normal issue path does.
1484 sdev
->device_busy
++;
1485 spin_unlock(sdev
->request_queue
->queue_lock
);
1486 spin_lock(shost
->host_lock
);
1488 starget
->target_busy
++;
1489 spin_unlock(shost
->host_lock
);
1490 spin_lock(sdev
->request_queue
->queue_lock
);
1492 blk_complete_request(req
);
1495 static void scsi_softirq_done(struct request
*rq
)
1497 struct scsi_cmnd
*cmd
= rq
->special
;
1498 unsigned long wait_for
= (cmd
->allowed
+ 1) * rq
->timeout
;
1501 INIT_LIST_HEAD(&cmd
->eh_entry
);
1504 * Set the serial numbers back to zero
1506 cmd
->serial_number
= 0;
1508 atomic_inc(&cmd
->device
->iodone_cnt
);
1510 atomic_inc(&cmd
->device
->ioerr_cnt
);
1512 disposition
= scsi_decide_disposition(cmd
);
1513 if (disposition
!= SUCCESS
&&
1514 time_before(cmd
->jiffies_at_alloc
+ wait_for
, jiffies
)) {
1515 sdev_printk(KERN_ERR
, cmd
->device
,
1516 "timing out command, waited %lus\n",
1518 disposition
= SUCCESS
;
1521 scsi_log_completion(cmd
, disposition
);
1523 switch (disposition
) {
1525 scsi_finish_command(cmd
);
1528 scsi_queue_insert(cmd
, SCSI_MLQUEUE_EH_RETRY
);
1530 case ADD_TO_MLQUEUE
:
1531 scsi_queue_insert(cmd
, SCSI_MLQUEUE_DEVICE_BUSY
);
1534 if (!scsi_eh_scmd_add(cmd
, 0))
1535 scsi_finish_command(cmd
);
1540 * Function: scsi_request_fn()
1542 * Purpose: Main strategy routine for SCSI.
1544 * Arguments: q - Pointer to actual queue.
1548 * Lock status: IO request lock assumed to be held when called.
1550 static void scsi_request_fn(struct request_queue
*q
)
1552 struct scsi_device
*sdev
= q
->queuedata
;
1553 struct Scsi_Host
*shost
;
1554 struct scsi_cmnd
*cmd
;
1555 struct request
*req
;
1558 printk("scsi: killing requests for dead queue\n");
1559 while ((req
= elv_next_request(q
)) != NULL
)
1560 scsi_kill_request(req
, q
);
1564 if(!get_device(&sdev
->sdev_gendev
))
1565 /* We must be tearing the block queue down already */
1569 * To start with, we keep looping until the queue is empty, or until
1570 * the host is no longer able to accept any more requests.
1573 while (!blk_queue_plugged(q
)) {
1576 * get next queueable request. We do this early to make sure
1577 * that the request is fully prepared even if we cannot
1580 req
= elv_next_request(q
);
1581 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1584 if (unlikely(!scsi_device_online(sdev
))) {
1585 sdev_printk(KERN_ERR
, sdev
,
1586 "rejecting I/O to offline device\n");
1587 scsi_kill_request(req
, q
);
1593 * Remove the request from the request list.
1595 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1596 blkdev_dequeue_request(req
);
1597 sdev
->device_busy
++;
1599 spin_unlock(q
->queue_lock
);
1601 if (unlikely(cmd
== NULL
)) {
1602 printk(KERN_CRIT
"impossible request in %s.\n"
1603 "please mail a stack trace to "
1604 "linux-scsi@vger.kernel.org\n",
1606 blk_dump_rq_flags(req
, "foo");
1609 spin_lock(shost
->host_lock
);
1612 * We hit this when the driver is using a host wide
1613 * tag map. For device level tag maps the queue_depth check
1614 * in the device ready fn would prevent us from trying
1615 * to allocate a tag. Since the map is a shared host resource
1616 * we add the dev to the starved list so it eventually gets
1617 * a run when a tag is freed.
1619 if (blk_queue_tagged(q
) && !blk_rq_tagged(req
)) {
1620 if (list_empty(&sdev
->starved_entry
))
1621 list_add_tail(&sdev
->starved_entry
,
1622 &shost
->starved_list
);
1626 if (!scsi_target_queue_ready(shost
, sdev
))
1629 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1632 scsi_target(sdev
)->target_busy
++;
1636 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1637 * take the lock again.
1639 spin_unlock_irq(shost
->host_lock
);
1642 * Finally, initialize any error handling parameters, and set up
1643 * the timers for timeouts.
1645 scsi_init_cmd_errh(cmd
);
1648 * Dispatch the command to the low-level driver.
1650 rtn
= scsi_dispatch_cmd(cmd
);
1651 spin_lock_irq(q
->queue_lock
);
1653 /* we're refusing the command; because of
1654 * the way locks get dropped, we need to
1655 * check here if plugging is required */
1656 if(sdev
->device_busy
== 0)
1666 spin_unlock_irq(shost
->host_lock
);
1669 * lock q, handle tag, requeue req, and decrement device_busy. We
1670 * must return with queue_lock held.
1672 * Decrementing device_busy without checking it is OK, as all such
1673 * cases (host limits or settings) should run the queue at some
1676 spin_lock_irq(q
->queue_lock
);
1677 blk_requeue_request(q
, req
);
1678 sdev
->device_busy
--;
1679 if(sdev
->device_busy
== 0)
1682 /* must be careful here...if we trigger the ->remove() function
1683 * we cannot be holding the q lock */
1684 spin_unlock_irq(q
->queue_lock
);
1685 put_device(&sdev
->sdev_gendev
);
1686 spin_lock_irq(q
->queue_lock
);
1689 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1691 struct device
*host_dev
;
1692 u64 bounce_limit
= 0xffffffff;
1694 if (shost
->unchecked_isa_dma
)
1695 return BLK_BOUNCE_ISA
;
1697 * Platforms with virtual-DMA translation
1698 * hardware have no practical limit.
1700 if (!PCI_DMA_BUS_IS_PHYS
)
1701 return BLK_BOUNCE_ANY
;
1703 host_dev
= scsi_get_device(shost
);
1704 if (host_dev
&& host_dev
->dma_mask
)
1705 bounce_limit
= *host_dev
->dma_mask
;
1707 return bounce_limit
;
1709 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1711 struct request_queue
*__scsi_alloc_queue(struct Scsi_Host
*shost
,
1712 request_fn_proc
*request_fn
)
1714 struct request_queue
*q
;
1715 struct device
*dev
= shost
->shost_gendev
.parent
;
1717 q
= blk_init_queue(request_fn
, NULL
);
1722 * this limit is imposed by hardware restrictions
1724 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1725 blk_queue_max_phys_segments(q
, SCSI_MAX_SG_CHAIN_SEGMENTS
);
1727 blk_queue_max_sectors(q
, shost
->max_sectors
);
1728 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1729 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1730 dma_set_seg_boundary(dev
, shost
->dma_boundary
);
1732 blk_queue_max_segment_size(q
, dma_get_max_seg_size(dev
));
1734 /* New queue, no concurrency on queue_flags */
1735 if (!shost
->use_clustering
)
1736 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER
, q
);
1739 * set a reasonable default alignment on word boundaries: the
1740 * host and device may alter it using
1741 * blk_queue_update_dma_alignment() later.
1743 blk_queue_dma_alignment(q
, 0x03);
1747 EXPORT_SYMBOL(__scsi_alloc_queue
);
1749 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1751 struct request_queue
*q
;
1753 q
= __scsi_alloc_queue(sdev
->host
, scsi_request_fn
);
1757 blk_queue_prep_rq(q
, scsi_prep_fn
);
1758 blk_queue_softirq_done(q
, scsi_softirq_done
);
1759 blk_queue_rq_timed_out(q
, scsi_times_out
);
1763 void scsi_free_queue(struct request_queue
*q
)
1765 blk_cleanup_queue(q
);
1769 * Function: scsi_block_requests()
1771 * Purpose: Utility function used by low-level drivers to prevent further
1772 * commands from being queued to the device.
1774 * Arguments: shost - Host in question
1778 * Lock status: No locks are assumed held.
1780 * Notes: There is no timer nor any other means by which the requests
1781 * get unblocked other than the low-level driver calling
1782 * scsi_unblock_requests().
1784 void scsi_block_requests(struct Scsi_Host
*shost
)
1786 shost
->host_self_blocked
= 1;
1788 EXPORT_SYMBOL(scsi_block_requests
);
1791 * Function: scsi_unblock_requests()
1793 * Purpose: Utility function used by low-level drivers to allow further
1794 * commands from being queued to the device.
1796 * Arguments: shost - Host in question
1800 * Lock status: No locks are assumed held.
1802 * Notes: There is no timer nor any other means by which the requests
1803 * get unblocked other than the low-level driver calling
1804 * scsi_unblock_requests().
1806 * This is done as an API function so that changes to the
1807 * internals of the scsi mid-layer won't require wholesale
1808 * changes to drivers that use this feature.
1810 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1812 shost
->host_self_blocked
= 0;
1813 scsi_run_host_queues(shost
);
1815 EXPORT_SYMBOL(scsi_unblock_requests
);
1817 int __init
scsi_init_queue(void)
1821 scsi_io_context_cache
= kmem_cache_create("scsi_io_context",
1822 sizeof(struct scsi_io_context
),
1824 if (!scsi_io_context_cache
) {
1825 printk(KERN_ERR
"SCSI: can't init scsi io context cache\n");
1829 scsi_sdb_cache
= kmem_cache_create("scsi_data_buffer",
1830 sizeof(struct scsi_data_buffer
),
1832 if (!scsi_sdb_cache
) {
1833 printk(KERN_ERR
"SCSI: can't init scsi sdb cache\n");
1834 goto cleanup_io_context
;
1837 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1838 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1839 int size
= sgp
->size
* sizeof(struct scatterlist
);
1841 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1842 SLAB_HWCACHE_ALIGN
, NULL
);
1844 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1849 sgp
->pool
= mempool_create_slab_pool(SG_MEMPOOL_SIZE
,
1852 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1861 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1862 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1864 mempool_destroy(sgp
->pool
);
1866 kmem_cache_destroy(sgp
->slab
);
1868 kmem_cache_destroy(scsi_sdb_cache
);
1870 kmem_cache_destroy(scsi_io_context_cache
);
1875 void scsi_exit_queue(void)
1879 kmem_cache_destroy(scsi_io_context_cache
);
1880 kmem_cache_destroy(scsi_sdb_cache
);
1882 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1883 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1884 mempool_destroy(sgp
->pool
);
1885 kmem_cache_destroy(sgp
->slab
);
1890 * scsi_mode_select - issue a mode select
1891 * @sdev: SCSI device to be queried
1892 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1893 * @sp: Save page bit (0 == don't save, 1 == save)
1894 * @modepage: mode page being requested
1895 * @buffer: request buffer (may not be smaller than eight bytes)
1896 * @len: length of request buffer.
1897 * @timeout: command timeout
1898 * @retries: number of retries before failing
1899 * @data: returns a structure abstracting the mode header data
1900 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1901 * must be SCSI_SENSE_BUFFERSIZE big.
1903 * Returns zero if successful; negative error number or scsi
1908 scsi_mode_select(struct scsi_device
*sdev
, int pf
, int sp
, int modepage
,
1909 unsigned char *buffer
, int len
, int timeout
, int retries
,
1910 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
)
1912 unsigned char cmd
[10];
1913 unsigned char *real_buffer
;
1916 memset(cmd
, 0, sizeof(cmd
));
1917 cmd
[1] = (pf
? 0x10 : 0) | (sp
? 0x01 : 0);
1919 if (sdev
->use_10_for_ms
) {
1922 real_buffer
= kmalloc(8 + len
, GFP_KERNEL
);
1925 memcpy(real_buffer
+ 8, buffer
, len
);
1929 real_buffer
[2] = data
->medium_type
;
1930 real_buffer
[3] = data
->device_specific
;
1931 real_buffer
[4] = data
->longlba
? 0x01 : 0;
1933 real_buffer
[6] = data
->block_descriptor_length
>> 8;
1934 real_buffer
[7] = data
->block_descriptor_length
;
1936 cmd
[0] = MODE_SELECT_10
;
1940 if (len
> 255 || data
->block_descriptor_length
> 255 ||
1944 real_buffer
= kmalloc(4 + len
, GFP_KERNEL
);
1947 memcpy(real_buffer
+ 4, buffer
, len
);
1950 real_buffer
[1] = data
->medium_type
;
1951 real_buffer
[2] = data
->device_specific
;
1952 real_buffer
[3] = data
->block_descriptor_length
;
1955 cmd
[0] = MODE_SELECT
;
1959 ret
= scsi_execute_req(sdev
, cmd
, DMA_TO_DEVICE
, real_buffer
, len
,
1960 sshdr
, timeout
, retries
);
1964 EXPORT_SYMBOL_GPL(scsi_mode_select
);
1967 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1968 * @sdev: SCSI device to be queried
1969 * @dbd: set if mode sense will allow block descriptors to be returned
1970 * @modepage: mode page being requested
1971 * @buffer: request buffer (may not be smaller than eight bytes)
1972 * @len: length of request buffer.
1973 * @timeout: command timeout
1974 * @retries: number of retries before failing
1975 * @data: returns a structure abstracting the mode header data
1976 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1977 * must be SCSI_SENSE_BUFFERSIZE big.
1979 * Returns zero if unsuccessful, or the header offset (either 4
1980 * or 8 depending on whether a six or ten byte command was
1981 * issued) if successful.
1984 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
1985 unsigned char *buffer
, int len
, int timeout
, int retries
,
1986 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
)
1988 unsigned char cmd
[12];
1992 struct scsi_sense_hdr my_sshdr
;
1994 memset(data
, 0, sizeof(*data
));
1995 memset(&cmd
[0], 0, 12);
1996 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
1999 /* caller might not be interested in sense, but we need it */
2004 use_10_for_ms
= sdev
->use_10_for_ms
;
2006 if (use_10_for_ms
) {
2010 cmd
[0] = MODE_SENSE_10
;
2017 cmd
[0] = MODE_SENSE
;
2022 memset(buffer
, 0, len
);
2024 result
= scsi_execute_req(sdev
, cmd
, DMA_FROM_DEVICE
, buffer
, len
,
2025 sshdr
, timeout
, retries
);
2027 /* This code looks awful: what it's doing is making sure an
2028 * ILLEGAL REQUEST sense return identifies the actual command
2029 * byte as the problem. MODE_SENSE commands can return
2030 * ILLEGAL REQUEST if the code page isn't supported */
2032 if (use_10_for_ms
&& !scsi_status_is_good(result
) &&
2033 (driver_byte(result
) & DRIVER_SENSE
)) {
2034 if (scsi_sense_valid(sshdr
)) {
2035 if ((sshdr
->sense_key
== ILLEGAL_REQUEST
) &&
2036 (sshdr
->asc
== 0x20) && (sshdr
->ascq
== 0)) {
2038 * Invalid command operation code
2040 sdev
->use_10_for_ms
= 0;
2046 if(scsi_status_is_good(result
)) {
2047 if (unlikely(buffer
[0] == 0x86 && buffer
[1] == 0x0b &&
2048 (modepage
== 6 || modepage
== 8))) {
2049 /* Initio breakage? */
2052 data
->medium_type
= 0;
2053 data
->device_specific
= 0;
2055 data
->block_descriptor_length
= 0;
2056 } else if(use_10_for_ms
) {
2057 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
2058 data
->medium_type
= buffer
[2];
2059 data
->device_specific
= buffer
[3];
2060 data
->longlba
= buffer
[4] & 0x01;
2061 data
->block_descriptor_length
= buffer
[6]*256
2064 data
->length
= buffer
[0] + 1;
2065 data
->medium_type
= buffer
[1];
2066 data
->device_specific
= buffer
[2];
2067 data
->block_descriptor_length
= buffer
[3];
2069 data
->header_length
= header_length
;
2074 EXPORT_SYMBOL(scsi_mode_sense
);
2077 * scsi_test_unit_ready - test if unit is ready
2078 * @sdev: scsi device to change the state of.
2079 * @timeout: command timeout
2080 * @retries: number of retries before failing
2081 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2082 * returning sense. Make sure that this is cleared before passing
2085 * Returns zero if unsuccessful or an error if TUR failed. For
2086 * removable media, a return of NOT_READY or UNIT_ATTENTION is
2087 * translated to success, with the ->changed flag updated.
2090 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
,
2091 struct scsi_sense_hdr
*sshdr_external
)
2094 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
2096 struct scsi_sense_hdr
*sshdr
;
2099 if (!sshdr_external
)
2100 sshdr
= kzalloc(sizeof(*sshdr
), GFP_KERNEL
);
2102 sshdr
= sshdr_external
;
2104 /* try to eat the UNIT_ATTENTION if there are enough retries */
2106 result
= scsi_execute_req(sdev
, cmd
, DMA_NONE
, NULL
, 0, sshdr
,
2108 } while ((driver_byte(result
) & DRIVER_SENSE
) &&
2109 sshdr
&& sshdr
->sense_key
== UNIT_ATTENTION
&&
2113 /* could not allocate sense buffer, so can't process it */
2116 if ((driver_byte(result
) & DRIVER_SENSE
) && sdev
->removable
) {
2118 if ((scsi_sense_valid(sshdr
)) &&
2119 ((sshdr
->sense_key
== UNIT_ATTENTION
) ||
2120 (sshdr
->sense_key
== NOT_READY
))) {
2125 if (!sshdr_external
)
2129 EXPORT_SYMBOL(scsi_test_unit_ready
);
2132 * scsi_device_set_state - Take the given device through the device state model.
2133 * @sdev: scsi device to change the state of.
2134 * @state: state to change to.
2136 * Returns zero if unsuccessful or an error if the requested
2137 * transition is illegal.
2140 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
2142 enum scsi_device_state oldstate
= sdev
->sdev_state
;
2144 if (state
== oldstate
)
2150 case SDEV_CREATED_BLOCK
:
2194 case SDEV_CREATED_BLOCK
:
2201 case SDEV_CREATED_BLOCK
:
2236 sdev
->sdev_state
= state
;
2240 SCSI_LOG_ERROR_RECOVERY(1,
2241 sdev_printk(KERN_ERR
, sdev
,
2242 "Illegal state transition %s->%s\n",
2243 scsi_device_state_name(oldstate
),
2244 scsi_device_state_name(state
))
2248 EXPORT_SYMBOL(scsi_device_set_state
);
2251 * sdev_evt_emit - emit a single SCSI device uevent
2252 * @sdev: associated SCSI device
2253 * @evt: event to emit
2255 * Send a single uevent (scsi_event) to the associated scsi_device.
2257 static void scsi_evt_emit(struct scsi_device
*sdev
, struct scsi_event
*evt
)
2262 switch (evt
->evt_type
) {
2263 case SDEV_EVT_MEDIA_CHANGE
:
2264 envp
[idx
++] = "SDEV_MEDIA_CHANGE=1";
2274 kobject_uevent_env(&sdev
->sdev_gendev
.kobj
, KOBJ_CHANGE
, envp
);
2278 * sdev_evt_thread - send a uevent for each scsi event
2279 * @work: work struct for scsi_device
2281 * Dispatch queued events to their associated scsi_device kobjects
2284 void scsi_evt_thread(struct work_struct
*work
)
2286 struct scsi_device
*sdev
;
2287 LIST_HEAD(event_list
);
2289 sdev
= container_of(work
, struct scsi_device
, event_work
);
2292 struct scsi_event
*evt
;
2293 struct list_head
*this, *tmp
;
2294 unsigned long flags
;
2296 spin_lock_irqsave(&sdev
->list_lock
, flags
);
2297 list_splice_init(&sdev
->event_list
, &event_list
);
2298 spin_unlock_irqrestore(&sdev
->list_lock
, flags
);
2300 if (list_empty(&event_list
))
2303 list_for_each_safe(this, tmp
, &event_list
) {
2304 evt
= list_entry(this, struct scsi_event
, node
);
2305 list_del(&evt
->node
);
2306 scsi_evt_emit(sdev
, evt
);
2313 * sdev_evt_send - send asserted event to uevent thread
2314 * @sdev: scsi_device event occurred on
2315 * @evt: event to send
2317 * Assert scsi device event asynchronously.
2319 void sdev_evt_send(struct scsi_device
*sdev
, struct scsi_event
*evt
)
2321 unsigned long flags
;
2324 /* FIXME: currently this check eliminates all media change events
2325 * for polled devices. Need to update to discriminate between AN
2326 * and polled events */
2327 if (!test_bit(evt
->evt_type
, sdev
->supported_events
)) {
2333 spin_lock_irqsave(&sdev
->list_lock
, flags
);
2334 list_add_tail(&evt
->node
, &sdev
->event_list
);
2335 schedule_work(&sdev
->event_work
);
2336 spin_unlock_irqrestore(&sdev
->list_lock
, flags
);
2338 EXPORT_SYMBOL_GPL(sdev_evt_send
);
2341 * sdev_evt_alloc - allocate a new scsi event
2342 * @evt_type: type of event to allocate
2343 * @gfpflags: GFP flags for allocation
2345 * Allocates and returns a new scsi_event.
2347 struct scsi_event
*sdev_evt_alloc(enum scsi_device_event evt_type
,
2350 struct scsi_event
*evt
= kzalloc(sizeof(struct scsi_event
), gfpflags
);
2354 evt
->evt_type
= evt_type
;
2355 INIT_LIST_HEAD(&evt
->node
);
2357 /* evt_type-specific initialization, if any */
2359 case SDEV_EVT_MEDIA_CHANGE
:
2367 EXPORT_SYMBOL_GPL(sdev_evt_alloc
);
2370 * sdev_evt_send_simple - send asserted event to uevent thread
2371 * @sdev: scsi_device event occurred on
2372 * @evt_type: type of event to send
2373 * @gfpflags: GFP flags for allocation
2375 * Assert scsi device event asynchronously, given an event type.
2377 void sdev_evt_send_simple(struct scsi_device
*sdev
,
2378 enum scsi_device_event evt_type
, gfp_t gfpflags
)
2380 struct scsi_event
*evt
= sdev_evt_alloc(evt_type
, gfpflags
);
2382 sdev_printk(KERN_ERR
, sdev
, "event %d eaten due to OOM\n",
2387 sdev_evt_send(sdev
, evt
);
2389 EXPORT_SYMBOL_GPL(sdev_evt_send_simple
);
2392 * scsi_device_quiesce - Block user issued commands.
2393 * @sdev: scsi device to quiesce.
2395 * This works by trying to transition to the SDEV_QUIESCE state
2396 * (which must be a legal transition). When the device is in this
2397 * state, only special requests will be accepted, all others will
2398 * be deferred. Since special requests may also be requeued requests,
2399 * a successful return doesn't guarantee the device will be
2400 * totally quiescent.
2402 * Must be called with user context, may sleep.
2404 * Returns zero if unsuccessful or an error if not.
2407 scsi_device_quiesce(struct scsi_device
*sdev
)
2409 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
2413 scsi_run_queue(sdev
->request_queue
);
2414 while (sdev
->device_busy
) {
2415 msleep_interruptible(200);
2416 scsi_run_queue(sdev
->request_queue
);
2420 EXPORT_SYMBOL(scsi_device_quiesce
);
2423 * scsi_device_resume - Restart user issued commands to a quiesced device.
2424 * @sdev: scsi device to resume.
2426 * Moves the device from quiesced back to running and restarts the
2429 * Must be called with user context, may sleep.
2432 scsi_device_resume(struct scsi_device
*sdev
)
2434 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
2436 scsi_run_queue(sdev
->request_queue
);
2438 EXPORT_SYMBOL(scsi_device_resume
);
2441 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
2443 scsi_device_quiesce(sdev
);
2447 scsi_target_quiesce(struct scsi_target
*starget
)
2449 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
2451 EXPORT_SYMBOL(scsi_target_quiesce
);
2454 device_resume_fn(struct scsi_device
*sdev
, void *data
)
2456 scsi_device_resume(sdev
);
2460 scsi_target_resume(struct scsi_target
*starget
)
2462 starget_for_each_device(starget
, NULL
, device_resume_fn
);
2464 EXPORT_SYMBOL(scsi_target_resume
);
2467 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2468 * @sdev: device to block
2470 * Block request made by scsi lld's to temporarily stop all
2471 * scsi commands on the specified device. Called from interrupt
2472 * or normal process context.
2474 * Returns zero if successful or error if not
2477 * This routine transitions the device to the SDEV_BLOCK state
2478 * (which must be a legal transition). When the device is in this
2479 * state, all commands are deferred until the scsi lld reenables
2480 * the device with scsi_device_unblock or device_block_tmo fires.
2481 * This routine assumes the host_lock is held on entry.
2484 scsi_internal_device_block(struct scsi_device
*sdev
)
2486 struct request_queue
*q
= sdev
->request_queue
;
2487 unsigned long flags
;
2490 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
2492 err
= scsi_device_set_state(sdev
, SDEV_CREATED_BLOCK
);
2499 * The device has transitioned to SDEV_BLOCK. Stop the
2500 * block layer from calling the midlayer with this device's
2503 spin_lock_irqsave(q
->queue_lock
, flags
);
2505 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2509 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
2512 * scsi_internal_device_unblock - resume a device after a block request
2513 * @sdev: device to resume
2515 * Called by scsi lld's or the midlayer to restart the device queue
2516 * for the previously suspended scsi device. Called from interrupt or
2517 * normal process context.
2519 * Returns zero if successful or error if not.
2522 * This routine transitions the device to the SDEV_RUNNING state
2523 * (which must be a legal transition) allowing the midlayer to
2524 * goose the queue for this device. This routine assumes the
2525 * host_lock is held upon entry.
2528 scsi_internal_device_unblock(struct scsi_device
*sdev
)
2530 struct request_queue
*q
= sdev
->request_queue
;
2532 unsigned long flags
;
2535 * Try to transition the scsi device to SDEV_RUNNING
2536 * and goose the device queue if successful.
2538 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
2540 err
= scsi_device_set_state(sdev
, SDEV_CREATED
);
2546 spin_lock_irqsave(q
->queue_lock
, flags
);
2548 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2552 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
2555 device_block(struct scsi_device
*sdev
, void *data
)
2557 scsi_internal_device_block(sdev
);
2561 target_block(struct device
*dev
, void *data
)
2563 if (scsi_is_target_device(dev
))
2564 starget_for_each_device(to_scsi_target(dev
), NULL
,
2570 scsi_target_block(struct device
*dev
)
2572 if (scsi_is_target_device(dev
))
2573 starget_for_each_device(to_scsi_target(dev
), NULL
,
2576 device_for_each_child(dev
, NULL
, target_block
);
2578 EXPORT_SYMBOL_GPL(scsi_target_block
);
2581 device_unblock(struct scsi_device
*sdev
, void *data
)
2583 scsi_internal_device_unblock(sdev
);
2587 target_unblock(struct device
*dev
, void *data
)
2589 if (scsi_is_target_device(dev
))
2590 starget_for_each_device(to_scsi_target(dev
), NULL
,
2596 scsi_target_unblock(struct device
*dev
)
2598 if (scsi_is_target_device(dev
))
2599 starget_for_each_device(to_scsi_target(dev
), NULL
,
2602 device_for_each_child(dev
, NULL
, target_unblock
);
2604 EXPORT_SYMBOL_GPL(scsi_target_unblock
);
2607 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2608 * @sgl: scatter-gather list
2609 * @sg_count: number of segments in sg
2610 * @offset: offset in bytes into sg, on return offset into the mapped area
2611 * @len: bytes to map, on return number of bytes mapped
2613 * Returns virtual address of the start of the mapped page
2615 void *scsi_kmap_atomic_sg(struct scatterlist
*sgl
, int sg_count
,
2616 size_t *offset
, size_t *len
)
2619 size_t sg_len
= 0, len_complete
= 0;
2620 struct scatterlist
*sg
;
2623 WARN_ON(!irqs_disabled());
2625 for_each_sg(sgl
, sg
, sg_count
, i
) {
2626 len_complete
= sg_len
; /* Complete sg-entries */
2627 sg_len
+= sg
->length
;
2628 if (sg_len
> *offset
)
2632 if (unlikely(i
== sg_count
)) {
2633 printk(KERN_ERR
"%s: Bytes in sg: %zu, requested offset %zu, "
2635 __func__
, sg_len
, *offset
, sg_count
);
2640 /* Offset starting from the beginning of first page in this sg-entry */
2641 *offset
= *offset
- len_complete
+ sg
->offset
;
2643 /* Assumption: contiguous pages can be accessed as "page + i" */
2644 page
= nth_page(sg_page(sg
), (*offset
>> PAGE_SHIFT
));
2645 *offset
&= ~PAGE_MASK
;
2647 /* Bytes in this sg-entry from *offset to the end of the page */
2648 sg_len
= PAGE_SIZE
- *offset
;
2652 return kmap_atomic(page
, KM_BIO_SRC_IRQ
);
2654 EXPORT_SYMBOL(scsi_kmap_atomic_sg
);
2657 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2658 * @virt: virtual address to be unmapped
2660 void scsi_kunmap_atomic_sg(void *virt
)
2662 kunmap_atomic(virt
, KM_BIO_SRC_IRQ
);
2664 EXPORT_SYMBOL(scsi_kunmap_atomic_sg
);