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;
186 * @resid: optional residual length
188 * returns the req->errors value which is the scsi_cmnd result
191 int scsi_execute(struct scsi_device
*sdev
, const unsigned char *cmd
,
192 int data_direction
, void *buffer
, unsigned bufflen
,
193 unsigned char *sense
, int timeout
, int retries
, int flags
,
197 int write
= (data_direction
== DMA_TO_DEVICE
);
198 int ret
= DRIVER_ERROR
<< 24;
200 req
= blk_get_request(sdev
->request_queue
, write
, __GFP_WAIT
);
202 if (bufflen
&& blk_rq_map_kern(sdev
->request_queue
, req
,
203 buffer
, bufflen
, __GFP_WAIT
))
206 req
->cmd_len
= COMMAND_SIZE(cmd
[0]);
207 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
210 req
->retries
= retries
;
211 req
->timeout
= timeout
;
212 req
->cmd_type
= REQ_TYPE_BLOCK_PC
;
213 req
->cmd_flags
|= flags
| REQ_QUIET
| REQ_PREEMPT
;
216 * head injection *required* here otherwise quiesce won't work
218 blk_execute_rq(req
->q
, NULL
, req
, 1);
221 * Some devices (USB mass-storage in particular) may transfer
222 * garbage data together with a residue indicating that the data
223 * is invalid. Prevent the garbage from being misinterpreted
224 * and prevent security leaks by zeroing out the excess data.
226 if (unlikely(req
->data_len
> 0 && req
->data_len
<= bufflen
))
227 memset(buffer
+ (bufflen
- req
->data_len
), 0, req
->data_len
);
230 *resid
= req
->data_len
;
233 blk_put_request(req
);
237 EXPORT_SYMBOL(scsi_execute
);
240 int scsi_execute_req(struct scsi_device
*sdev
, const unsigned char *cmd
,
241 int data_direction
, void *buffer
, unsigned bufflen
,
242 struct scsi_sense_hdr
*sshdr
, int timeout
, int retries
,
249 sense
= kzalloc(SCSI_SENSE_BUFFERSIZE
, GFP_NOIO
);
251 return DRIVER_ERROR
<< 24;
253 result
= scsi_execute(sdev
, cmd
, data_direction
, buffer
, bufflen
,
254 sense
, timeout
, retries
, 0, resid
);
256 scsi_normalize_sense(sense
, SCSI_SENSE_BUFFERSIZE
, sshdr
);
261 EXPORT_SYMBOL(scsi_execute_req
);
263 struct scsi_io_context
{
265 void (*done
)(void *data
, char *sense
, int result
, int resid
);
266 char sense
[SCSI_SENSE_BUFFERSIZE
];
269 static struct kmem_cache
*scsi_io_context_cache
;
271 static void scsi_end_async(struct request
*req
, int uptodate
)
273 struct scsi_io_context
*sioc
= req
->end_io_data
;
276 sioc
->done(sioc
->data
, sioc
->sense
, req
->errors
, req
->data_len
);
278 kmem_cache_free(scsi_io_context_cache
, sioc
);
279 __blk_put_request(req
->q
, req
);
282 static int scsi_merge_bio(struct request
*rq
, struct bio
*bio
)
284 struct request_queue
*q
= rq
->q
;
286 bio
->bi_flags
&= ~(1 << BIO_SEG_VALID
);
287 if (rq_data_dir(rq
) == WRITE
)
288 bio
->bi_rw
|= (1 << BIO_RW
);
289 blk_queue_bounce(q
, &bio
);
291 return blk_rq_append_bio(q
, rq
, bio
);
294 static void scsi_bi_endio(struct bio
*bio
, int error
)
300 * scsi_req_map_sg - map a scatterlist into a request
301 * @rq: request to fill
303 * @nsegs: number of elements
304 * @bufflen: len of buffer
305 * @gfp: memory allocation flags
307 * scsi_req_map_sg maps a scatterlist into a request so that the
308 * request can be sent to the block layer. We do not trust the scatterlist
309 * sent to use, as some ULDs use that struct to only organize the pages.
311 static int scsi_req_map_sg(struct request
*rq
, struct scatterlist
*sgl
,
312 int nsegs
, unsigned bufflen
, gfp_t gfp
)
314 struct request_queue
*q
= rq
->q
;
315 int nr_pages
= (bufflen
+ sgl
[0].offset
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
316 unsigned int data_len
= bufflen
, len
, bytes
, off
;
317 struct scatterlist
*sg
;
319 struct bio
*bio
= NULL
;
320 int i
, err
, nr_vecs
= 0;
322 for_each_sg(sgl
, sg
, nsegs
, i
) {
327 while (len
> 0 && data_len
> 0) {
329 * sg sends a scatterlist that is larger than
330 * the data_len it wants transferred for certain
333 bytes
= min_t(unsigned int, len
, PAGE_SIZE
- off
);
334 bytes
= min(bytes
, data_len
);
337 nr_vecs
= min_t(int, BIO_MAX_PAGES
, nr_pages
);
340 bio
= bio_alloc(gfp
, nr_vecs
);
345 bio
->bi_end_io
= scsi_bi_endio
;
348 if (bio_add_pc_page(q
, bio
, page
, bytes
, off
) !=
355 if (bio
->bi_vcnt
>= nr_vecs
) {
356 err
= scsi_merge_bio(rq
, bio
);
371 rq
->buffer
= rq
->data
= NULL
;
372 rq
->data_len
= bufflen
;
376 while ((bio
= rq
->bio
) != NULL
) {
377 rq
->bio
= bio
->bi_next
;
379 * call endio instead of bio_put incase it was bounced
388 * scsi_execute_async - insert request
391 * @cmd_len: length of scsi cdb
392 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
393 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
394 * @bufflen: len of buffer
395 * @use_sg: if buffer is a scatterlist this is the number of elements
396 * @timeout: request timeout in seconds
397 * @retries: number of times to retry request
398 * @privdata: data passed to done()
399 * @done: callback function when done
400 * @gfp: memory allocation flags
402 int scsi_execute_async(struct scsi_device
*sdev
, const unsigned char *cmd
,
403 int cmd_len
, int data_direction
, void *buffer
, unsigned bufflen
,
404 int use_sg
, int timeout
, int retries
, void *privdata
,
405 void (*done
)(void *, char *, int, int), gfp_t gfp
)
408 struct scsi_io_context
*sioc
;
410 int write
= (data_direction
== DMA_TO_DEVICE
);
412 sioc
= kmem_cache_zalloc(scsi_io_context_cache
, gfp
);
414 return DRIVER_ERROR
<< 24;
416 req
= blk_get_request(sdev
->request_queue
, write
, gfp
);
419 req
->cmd_type
= REQ_TYPE_BLOCK_PC
;
420 req
->cmd_flags
|= REQ_QUIET
;
423 err
= scsi_req_map_sg(req
, buffer
, use_sg
, bufflen
, gfp
);
425 err
= blk_rq_map_kern(req
->q
, req
, buffer
, bufflen
, gfp
);
430 req
->cmd_len
= cmd_len
;
431 memset(req
->cmd
, 0, BLK_MAX_CDB
); /* ATAPI hates garbage after CDB */
432 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
433 req
->sense
= sioc
->sense
;
435 req
->timeout
= timeout
;
436 req
->retries
= retries
;
437 req
->end_io_data
= sioc
;
439 sioc
->data
= privdata
;
442 blk_execute_rq_nowait(req
->q
, NULL
, req
, 1, scsi_end_async
);
446 blk_put_request(req
);
448 kmem_cache_free(scsi_io_context_cache
, sioc
);
449 return DRIVER_ERROR
<< 24;
451 EXPORT_SYMBOL_GPL(scsi_execute_async
);
454 * Function: scsi_init_cmd_errh()
456 * Purpose: Initialize cmd fields related to error handling.
458 * Arguments: cmd - command that is ready to be queued.
460 * Notes: This function has the job of initializing a number of
461 * fields related to error handling. Typically this will
462 * be called once for each command, as required.
464 static void scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
466 cmd
->serial_number
= 0;
467 scsi_set_resid(cmd
, 0);
468 memset(cmd
->sense_buffer
, 0, SCSI_SENSE_BUFFERSIZE
);
469 if (cmd
->cmd_len
== 0)
470 cmd
->cmd_len
= scsi_command_size(cmd
->cmnd
);
473 void scsi_device_unbusy(struct scsi_device
*sdev
)
475 struct Scsi_Host
*shost
= sdev
->host
;
476 struct scsi_target
*starget
= scsi_target(sdev
);
479 spin_lock_irqsave(shost
->host_lock
, flags
);
481 starget
->target_busy
--;
482 if (unlikely(scsi_host_in_recovery(shost
) &&
483 (shost
->host_failed
|| shost
->host_eh_scheduled
)))
484 scsi_eh_wakeup(shost
);
485 spin_unlock(shost
->host_lock
);
486 spin_lock(sdev
->request_queue
->queue_lock
);
488 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
492 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
493 * and call blk_run_queue for all the scsi_devices on the target -
494 * including current_sdev first.
496 * Called with *no* scsi locks held.
498 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
500 struct Scsi_Host
*shost
= current_sdev
->host
;
501 struct scsi_device
*sdev
, *tmp
;
502 struct scsi_target
*starget
= scsi_target(current_sdev
);
505 spin_lock_irqsave(shost
->host_lock
, flags
);
506 starget
->starget_sdev_user
= NULL
;
507 spin_unlock_irqrestore(shost
->host_lock
, flags
);
510 * Call blk_run_queue for all LUNs on the target, starting with
511 * current_sdev. We race with others (to set starget_sdev_user),
512 * but in most cases, we will be first. Ideally, each LU on the
513 * target would get some limited time or requests on the target.
515 blk_run_queue(current_sdev
->request_queue
);
517 spin_lock_irqsave(shost
->host_lock
, flags
);
518 if (starget
->starget_sdev_user
)
520 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
521 same_target_siblings
) {
522 if (sdev
== current_sdev
)
524 if (scsi_device_get(sdev
))
527 spin_unlock_irqrestore(shost
->host_lock
, flags
);
528 blk_run_queue(sdev
->request_queue
);
529 spin_lock_irqsave(shost
->host_lock
, flags
);
531 scsi_device_put(sdev
);
534 spin_unlock_irqrestore(shost
->host_lock
, flags
);
537 static inline int scsi_device_is_busy(struct scsi_device
*sdev
)
539 if (sdev
->device_busy
>= sdev
->queue_depth
|| sdev
->device_blocked
)
545 static inline int scsi_target_is_busy(struct scsi_target
*starget
)
547 return ((starget
->can_queue
> 0 &&
548 starget
->target_busy
>= starget
->can_queue
) ||
549 starget
->target_blocked
);
552 static inline int scsi_host_is_busy(struct Scsi_Host
*shost
)
554 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
555 shost
->host_blocked
|| shost
->host_self_blocked
)
562 * Function: scsi_run_queue()
564 * Purpose: Select a proper request queue to serve next
566 * Arguments: q - last request's queue
570 * Notes: The previous command was completely finished, start
571 * a new one if possible.
573 static void scsi_run_queue(struct request_queue
*q
)
575 struct scsi_device
*sdev
= q
->queuedata
;
576 struct Scsi_Host
*shost
= sdev
->host
;
577 LIST_HEAD(starved_list
);
580 if (scsi_target(sdev
)->single_lun
)
581 scsi_single_lun_run(sdev
);
583 spin_lock_irqsave(shost
->host_lock
, flags
);
584 list_splice_init(&shost
->starved_list
, &starved_list
);
586 while (!list_empty(&starved_list
)) {
590 * As long as shost is accepting commands and we have
591 * starved queues, call blk_run_queue. scsi_request_fn
592 * drops the queue_lock and can add us back to the
595 * host_lock protects the starved_list and starved_entry.
596 * scsi_request_fn must get the host_lock before checking
597 * or modifying starved_list or starved_entry.
599 if (scsi_host_is_busy(shost
))
602 sdev
= list_entry(starved_list
.next
,
603 struct scsi_device
, starved_entry
);
604 list_del_init(&sdev
->starved_entry
);
605 if (scsi_target_is_busy(scsi_target(sdev
))) {
606 list_move_tail(&sdev
->starved_entry
,
607 &shost
->starved_list
);
611 spin_unlock(shost
->host_lock
);
613 spin_lock(sdev
->request_queue
->queue_lock
);
614 flagset
= test_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
) &&
615 !test_bit(QUEUE_FLAG_REENTER
,
616 &sdev
->request_queue
->queue_flags
);
618 queue_flag_set(QUEUE_FLAG_REENTER
, sdev
->request_queue
);
619 __blk_run_queue(sdev
->request_queue
);
621 queue_flag_clear(QUEUE_FLAG_REENTER
, sdev
->request_queue
);
622 spin_unlock(sdev
->request_queue
->queue_lock
);
624 spin_lock(shost
->host_lock
);
626 /* put any unprocessed entries back */
627 list_splice(&starved_list
, &shost
->starved_list
);
628 spin_unlock_irqrestore(shost
->host_lock
, flags
);
634 * Function: scsi_requeue_command()
636 * Purpose: Handle post-processing of completed commands.
638 * Arguments: q - queue to operate on
639 * cmd - command that may need to be requeued.
643 * Notes: After command completion, there may be blocks left
644 * over which weren't finished by the previous command
645 * this can be for a number of reasons - the main one is
646 * I/O errors in the middle of the request, in which case
647 * we need to request the blocks that come after the bad
649 * Notes: Upon return, cmd is a stale pointer.
651 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
653 struct request
*req
= cmd
->request
;
656 spin_lock_irqsave(q
->queue_lock
, flags
);
657 scsi_unprep_request(req
);
658 blk_requeue_request(q
, req
);
659 spin_unlock_irqrestore(q
->queue_lock
, flags
);
664 void scsi_next_command(struct scsi_cmnd
*cmd
)
666 struct scsi_device
*sdev
= cmd
->device
;
667 struct request_queue
*q
= sdev
->request_queue
;
669 /* need to hold a reference on the device before we let go of the cmd */
670 get_device(&sdev
->sdev_gendev
);
672 scsi_put_command(cmd
);
675 /* ok to remove device now */
676 put_device(&sdev
->sdev_gendev
);
679 void scsi_run_host_queues(struct Scsi_Host
*shost
)
681 struct scsi_device
*sdev
;
683 shost_for_each_device(sdev
, shost
)
684 scsi_run_queue(sdev
->request_queue
);
688 * Function: scsi_end_request()
690 * Purpose: Post-processing of completed commands (usually invoked at end
691 * of upper level post-processing and scsi_io_completion).
693 * Arguments: cmd - command that is complete.
694 * error - 0 if I/O indicates success, < 0 for I/O error.
695 * bytes - number of bytes of completed I/O
696 * requeue - indicates whether we should requeue leftovers.
698 * Lock status: Assumed that lock is not held upon entry.
700 * Returns: cmd if requeue required, NULL otherwise.
702 * Notes: This is called for block device requests in order to
703 * mark some number of sectors as complete.
705 * We are guaranteeing that the request queue will be goosed
706 * at some point during this call.
707 * Notes: If cmd was requeued, upon return it will be a stale pointer.
709 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int error
,
710 int bytes
, int requeue
)
712 struct request_queue
*q
= cmd
->device
->request_queue
;
713 struct request
*req
= cmd
->request
;
716 * If there are blocks left over at the end, set up the command
717 * to queue the remainder of them.
719 if (blk_end_request(req
, error
, bytes
)) {
720 int leftover
= (req
->hard_nr_sectors
<< 9);
722 if (blk_pc_request(req
))
723 leftover
= req
->data_len
;
725 /* kill remainder if no retrys */
726 if (error
&& scsi_noretry_cmd(cmd
))
727 blk_end_request(req
, error
, leftover
);
731 * Bleah. Leftovers again. Stick the
732 * leftovers in the front of the
733 * queue, and goose the queue again.
735 scsi_requeue_command(q
, cmd
);
743 * This will goose the queue request function at the end, so we don't
744 * need to worry about launching another command.
746 scsi_next_command(cmd
);
750 static inline unsigned int scsi_sgtable_index(unsigned short nents
)
754 BUG_ON(nents
> SCSI_MAX_SG_SEGMENTS
);
759 index
= get_count_order(nents
) - 3;
764 static void scsi_sg_free(struct scatterlist
*sgl
, unsigned int nents
)
766 struct scsi_host_sg_pool
*sgp
;
768 sgp
= scsi_sg_pools
+ scsi_sgtable_index(nents
);
769 mempool_free(sgl
, sgp
->pool
);
772 static struct scatterlist
*scsi_sg_alloc(unsigned int nents
, gfp_t gfp_mask
)
774 struct scsi_host_sg_pool
*sgp
;
776 sgp
= scsi_sg_pools
+ scsi_sgtable_index(nents
);
777 return mempool_alloc(sgp
->pool
, gfp_mask
);
780 static int scsi_alloc_sgtable(struct scsi_data_buffer
*sdb
, int nents
,
787 ret
= __sg_alloc_table(&sdb
->table
, nents
, SCSI_MAX_SG_SEGMENTS
,
788 gfp_mask
, scsi_sg_alloc
);
790 __sg_free_table(&sdb
->table
, SCSI_MAX_SG_SEGMENTS
,
796 static void scsi_free_sgtable(struct scsi_data_buffer
*sdb
)
798 __sg_free_table(&sdb
->table
, SCSI_MAX_SG_SEGMENTS
, scsi_sg_free
);
802 * Function: scsi_release_buffers()
804 * Purpose: Completion processing for block device I/O requests.
806 * Arguments: cmd - command that we are bailing.
808 * Lock status: Assumed that no lock is held upon entry.
812 * Notes: In the event that an upper level driver rejects a
813 * command, we must release resources allocated during
814 * the __init_io() function. Primarily this would involve
815 * the scatter-gather table, and potentially any bounce
818 void scsi_release_buffers(struct scsi_cmnd
*cmd
)
820 if (cmd
->sdb
.table
.nents
)
821 scsi_free_sgtable(&cmd
->sdb
);
823 memset(&cmd
->sdb
, 0, sizeof(cmd
->sdb
));
825 if (scsi_bidi_cmnd(cmd
)) {
826 struct scsi_data_buffer
*bidi_sdb
=
827 cmd
->request
->next_rq
->special
;
828 scsi_free_sgtable(bidi_sdb
);
829 kmem_cache_free(scsi_sdb_cache
, bidi_sdb
);
830 cmd
->request
->next_rq
->special
= NULL
;
833 if (scsi_prot_sg_count(cmd
))
834 scsi_free_sgtable(cmd
->prot_sdb
);
836 EXPORT_SYMBOL(scsi_release_buffers
);
839 * Bidi commands Must be complete as a whole, both sides at once.
840 * If part of the bytes were written and lld returned
841 * scsi_in()->resid and/or scsi_out()->resid this information will be left
842 * in req->data_len and req->next_rq->data_len. The upper-layer driver can
843 * decide what to do with this information.
845 static void scsi_end_bidi_request(struct scsi_cmnd
*cmd
)
847 struct request
*req
= cmd
->request
;
848 unsigned int dlen
= req
->data_len
;
849 unsigned int next_dlen
= req
->next_rq
->data_len
;
851 req
->data_len
= scsi_out(cmd
)->resid
;
852 req
->next_rq
->data_len
= scsi_in(cmd
)->resid
;
854 /* The req and req->next_rq have not been completed */
855 BUG_ON(blk_end_bidi_request(req
, 0, dlen
, next_dlen
));
857 scsi_release_buffers(cmd
);
860 * This will goose the queue request function at the end, so we don't
861 * need to worry about launching another command.
863 scsi_next_command(cmd
);
867 * Function: scsi_io_completion()
869 * Purpose: Completion processing for block device I/O requests.
871 * Arguments: cmd - command that is finished.
873 * Lock status: Assumed that no lock is held upon entry.
877 * Notes: This function is matched in terms of capabilities to
878 * the function that created the scatter-gather list.
879 * In other words, if there are no bounce buffers
880 * (the normal case for most drivers), we don't need
881 * the logic to deal with cleaning up afterwards.
883 * We must call scsi_end_request(). This will finish off
884 * the specified number of sectors. If we are done, the
885 * command block will be released and the queue function
886 * will be goosed. If we are not done then we have to
887 * figure out what to do next:
889 * a) We can call scsi_requeue_command(). The request
890 * will be unprepared and put back on the queue. Then
891 * a new command will be created for it. This should
892 * be used if we made forward progress, or if we want
893 * to switch from READ(10) to READ(6) for example.
895 * b) We can call scsi_queue_insert(). The request will
896 * be put back on the queue and retried using the same
897 * command as before, possibly after a delay.
899 * c) We can call blk_end_request() with -EIO to fail
900 * the remainder of the request.
902 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
)
904 int result
= cmd
->result
;
906 struct request_queue
*q
= cmd
->device
->request_queue
;
907 struct request
*req
= cmd
->request
;
909 struct scsi_sense_hdr sshdr
;
911 int sense_deferred
= 0;
912 enum {ACTION_FAIL
, ACTION_REPREP
, ACTION_RETRY
,
913 ACTION_DELAYED_RETRY
} action
;
914 char *description
= NULL
;
917 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
919 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
922 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
923 req
->errors
= result
;
925 if (sense_valid
&& req
->sense
) {
927 * SG_IO wants current and deferred errors
929 int len
= 8 + cmd
->sense_buffer
[7];
931 if (len
> SCSI_SENSE_BUFFERSIZE
)
932 len
= SCSI_SENSE_BUFFERSIZE
;
933 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
934 req
->sense_len
= len
;
939 if (scsi_bidi_cmnd(cmd
)) {
940 /* will also release_buffers */
941 scsi_end_bidi_request(cmd
);
944 req
->data_len
= scsi_get_resid(cmd
);
947 BUG_ON(blk_bidi_rq(req
)); /* bidi not support for !blk_pc_request yet */
948 scsi_release_buffers(cmd
);
951 * Next deal with any sectors which we were able to correctly
954 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
956 req
->nr_sectors
, good_bytes
));
958 /* A number of bytes were successfully read. If there
959 * are leftovers and there is some kind of error
960 * (result != 0), retry the rest.
962 if (scsi_end_request(cmd
, error
, good_bytes
, result
== 0) == NULL
)
964 this_count
= blk_rq_bytes(req
);
966 if (host_byte(result
) == DID_RESET
) {
967 /* Third party bus reset or reset for error recovery
968 * reasons. Just retry the command and see what
971 action
= ACTION_RETRY
;
972 } else if (sense_valid
&& !sense_deferred
) {
973 switch (sshdr
.sense_key
) {
975 if (cmd
->device
->removable
) {
976 /* Detected disc change. Set a bit
977 * and quietly refuse further access.
979 cmd
->device
->changed
= 1;
980 description
= "Media Changed";
981 action
= ACTION_FAIL
;
983 /* Must have been a power glitch, or a
984 * bus reset. Could not have been a
985 * media change, so we just retry the
986 * command and see what happens.
988 action
= ACTION_RETRY
;
991 case ILLEGAL_REQUEST
:
992 /* If we had an ILLEGAL REQUEST returned, then
993 * we may have performed an unsupported
994 * command. The only thing this should be
995 * would be a ten byte read where only a six
996 * byte read was supported. Also, on a system
997 * where READ CAPACITY failed, we may have
998 * read past the end of the disk.
1000 if ((cmd
->device
->use_10_for_rw
&&
1001 sshdr
.asc
== 0x20 && sshdr
.ascq
== 0x00) &&
1002 (cmd
->cmnd
[0] == READ_10
||
1003 cmd
->cmnd
[0] == WRITE_10
)) {
1004 /* This will issue a new 6-byte command. */
1005 cmd
->device
->use_10_for_rw
= 0;
1006 action
= ACTION_REPREP
;
1008 action
= ACTION_FAIL
;
1010 case ABORTED_COMMAND
:
1011 if (sshdr
.asc
== 0x10) { /* DIF */
1012 action
= ACTION_FAIL
;
1013 description
= "Data Integrity Failure";
1015 action
= ACTION_RETRY
;
1018 /* If the device is in the process of becoming
1019 * ready, or has a temporary blockage, retry.
1021 if (sshdr
.asc
== 0x04) {
1022 switch (sshdr
.ascq
) {
1023 case 0x01: /* becoming ready */
1024 case 0x04: /* format in progress */
1025 case 0x05: /* rebuild in progress */
1026 case 0x06: /* recalculation in progress */
1027 case 0x07: /* operation in progress */
1028 case 0x08: /* Long write in progress */
1029 case 0x09: /* self test in progress */
1030 action
= ACTION_DELAYED_RETRY
;
1034 description
= "Device not ready";
1035 action
= ACTION_FAIL
;
1038 case VOLUME_OVERFLOW
:
1039 /* See SSC3rXX or current. */
1040 action
= ACTION_FAIL
;
1043 description
= "Unhandled sense code";
1044 action
= ACTION_FAIL
;
1048 description
= "Unhandled error code";
1049 action
= ACTION_FAIL
;
1054 /* Give up and fail the remainder of the request */
1055 if (!(req
->cmd_flags
& REQ_QUIET
)) {
1057 scmd_printk(KERN_INFO
, cmd
, "%s",
1059 scsi_print_result(cmd
);
1060 if (driver_byte(result
) & DRIVER_SENSE
)
1061 scsi_print_sense("", cmd
);
1063 blk_end_request(req
, -EIO
, blk_rq_bytes(req
));
1064 scsi_next_command(cmd
);
1067 /* Unprep the request and put it back at the head of the queue.
1068 * A new command will be prepared and issued.
1070 scsi_requeue_command(q
, cmd
);
1073 /* Retry the same command immediately */
1074 scsi_queue_insert(cmd
, SCSI_MLQUEUE_EH_RETRY
);
1076 case ACTION_DELAYED_RETRY
:
1077 /* Retry the same command after a delay */
1078 scsi_queue_insert(cmd
, SCSI_MLQUEUE_DEVICE_BUSY
);
1083 static int scsi_init_sgtable(struct request
*req
, struct scsi_data_buffer
*sdb
,
1089 * If sg table allocation fails, requeue request later.
1091 if (unlikely(scsi_alloc_sgtable(sdb
, req
->nr_phys_segments
,
1093 return BLKPREP_DEFER
;
1099 * Next, walk the list, and fill in the addresses and sizes of
1102 count
= blk_rq_map_sg(req
->q
, req
, sdb
->table
.sgl
);
1103 BUG_ON(count
> sdb
->table
.nents
);
1104 sdb
->table
.nents
= count
;
1105 if (blk_pc_request(req
))
1106 sdb
->length
= req
->data_len
;
1108 sdb
->length
= req
->nr_sectors
<< 9;
1113 * Function: scsi_init_io()
1115 * Purpose: SCSI I/O initialize function.
1117 * Arguments: cmd - Command descriptor we wish to initialize
1119 * Returns: 0 on success
1120 * BLKPREP_DEFER if the failure is retryable
1121 * BLKPREP_KILL if the failure is fatal
1123 int scsi_init_io(struct scsi_cmnd
*cmd
, gfp_t gfp_mask
)
1125 int error
= scsi_init_sgtable(cmd
->request
, &cmd
->sdb
, gfp_mask
);
1129 if (blk_bidi_rq(cmd
->request
)) {
1130 struct scsi_data_buffer
*bidi_sdb
= kmem_cache_zalloc(
1131 scsi_sdb_cache
, GFP_ATOMIC
);
1133 error
= BLKPREP_DEFER
;
1137 cmd
->request
->next_rq
->special
= bidi_sdb
;
1138 error
= scsi_init_sgtable(cmd
->request
->next_rq
, bidi_sdb
,
1144 if (blk_integrity_rq(cmd
->request
)) {
1145 struct scsi_data_buffer
*prot_sdb
= cmd
->prot_sdb
;
1148 BUG_ON(prot_sdb
== NULL
);
1149 ivecs
= blk_rq_count_integrity_sg(cmd
->request
);
1151 if (scsi_alloc_sgtable(prot_sdb
, ivecs
, gfp_mask
)) {
1152 error
= BLKPREP_DEFER
;
1156 count
= blk_rq_map_integrity_sg(cmd
->request
,
1157 prot_sdb
->table
.sgl
);
1158 BUG_ON(unlikely(count
> ivecs
));
1160 cmd
->prot_sdb
= prot_sdb
;
1161 cmd
->prot_sdb
->table
.nents
= count
;
1167 scsi_release_buffers(cmd
);
1168 if (error
== BLKPREP_KILL
)
1169 scsi_put_command(cmd
);
1170 else /* BLKPREP_DEFER */
1171 scsi_unprep_request(cmd
->request
);
1175 EXPORT_SYMBOL(scsi_init_io
);
1177 static struct scsi_cmnd
*scsi_get_cmd_from_req(struct scsi_device
*sdev
,
1178 struct request
*req
)
1180 struct scsi_cmnd
*cmd
;
1182 if (!req
->special
) {
1183 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1191 /* pull a tag out of the request if we have one */
1192 cmd
->tag
= req
->tag
;
1195 cmd
->cmnd
= req
->cmd
;
1200 int scsi_setup_blk_pc_cmnd(struct scsi_device
*sdev
, struct request
*req
)
1202 struct scsi_cmnd
*cmd
;
1203 int ret
= scsi_prep_state_check(sdev
, req
);
1205 if (ret
!= BLKPREP_OK
)
1208 cmd
= scsi_get_cmd_from_req(sdev
, req
);
1210 return BLKPREP_DEFER
;
1213 * BLOCK_PC requests may transfer data, in which case they must
1214 * a bio attached to them. Or they might contain a SCSI command
1215 * that does not transfer data, in which case they may optionally
1216 * submit a request without an attached bio.
1221 BUG_ON(!req
->nr_phys_segments
);
1223 ret
= scsi_init_io(cmd
, GFP_ATOMIC
);
1227 BUG_ON(req
->data_len
);
1230 memset(&cmd
->sdb
, 0, sizeof(cmd
->sdb
));
1234 cmd
->cmd_len
= req
->cmd_len
;
1236 cmd
->sc_data_direction
= DMA_NONE
;
1237 else if (rq_data_dir(req
) == WRITE
)
1238 cmd
->sc_data_direction
= DMA_TO_DEVICE
;
1240 cmd
->sc_data_direction
= DMA_FROM_DEVICE
;
1242 cmd
->transfersize
= req
->data_len
;
1243 cmd
->allowed
= req
->retries
;
1246 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd
);
1249 * Setup a REQ_TYPE_FS command. These are simple read/write request
1250 * from filesystems that still need to be translated to SCSI CDBs from
1253 int scsi_setup_fs_cmnd(struct scsi_device
*sdev
, struct request
*req
)
1255 struct scsi_cmnd
*cmd
;
1256 int ret
= scsi_prep_state_check(sdev
, req
);
1258 if (ret
!= BLKPREP_OK
)
1261 if (unlikely(sdev
->scsi_dh_data
&& sdev
->scsi_dh_data
->scsi_dh
1262 && sdev
->scsi_dh_data
->scsi_dh
->prep_fn
)) {
1263 ret
= sdev
->scsi_dh_data
->scsi_dh
->prep_fn(sdev
, req
);
1264 if (ret
!= BLKPREP_OK
)
1269 * Filesystem requests must transfer data.
1271 BUG_ON(!req
->nr_phys_segments
);
1273 cmd
= scsi_get_cmd_from_req(sdev
, req
);
1275 return BLKPREP_DEFER
;
1277 memset(cmd
->cmnd
, 0, BLK_MAX_CDB
);
1278 return scsi_init_io(cmd
, GFP_ATOMIC
);
1280 EXPORT_SYMBOL(scsi_setup_fs_cmnd
);
1282 int scsi_prep_state_check(struct scsi_device
*sdev
, struct request
*req
)
1284 int ret
= BLKPREP_OK
;
1287 * If the device is not in running state we will reject some
1290 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1291 switch (sdev
->sdev_state
) {
1294 * If the device is offline we refuse to process any
1295 * commands. The device must be brought online
1296 * before trying any recovery commands.
1298 sdev_printk(KERN_ERR
, sdev
,
1299 "rejecting I/O to offline device\n");
1304 * If the device is fully deleted, we refuse to
1305 * process any commands as well.
1307 sdev_printk(KERN_ERR
, sdev
,
1308 "rejecting I/O to dead device\n");
1313 case SDEV_CREATED_BLOCK
:
1315 * If the devices is blocked we defer normal commands.
1317 if (!(req
->cmd_flags
& REQ_PREEMPT
))
1318 ret
= BLKPREP_DEFER
;
1322 * For any other not fully online state we only allow
1323 * special commands. In particular any user initiated
1324 * command is not allowed.
1326 if (!(req
->cmd_flags
& REQ_PREEMPT
))
1333 EXPORT_SYMBOL(scsi_prep_state_check
);
1335 int scsi_prep_return(struct request_queue
*q
, struct request
*req
, int ret
)
1337 struct scsi_device
*sdev
= q
->queuedata
;
1341 req
->errors
= DID_NO_CONNECT
<< 16;
1342 /* release the command and kill it */
1344 struct scsi_cmnd
*cmd
= req
->special
;
1345 scsi_release_buffers(cmd
);
1346 scsi_put_command(cmd
);
1347 req
->special
= NULL
;
1352 * If we defer, the elv_next_request() returns NULL, but the
1353 * queue must be restarted, so we plug here if no returning
1354 * command will automatically do that.
1356 if (sdev
->device_busy
== 0)
1360 req
->cmd_flags
|= REQ_DONTPREP
;
1365 EXPORT_SYMBOL(scsi_prep_return
);
1367 int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1369 struct scsi_device
*sdev
= q
->queuedata
;
1370 int ret
= BLKPREP_KILL
;
1372 if (req
->cmd_type
== REQ_TYPE_BLOCK_PC
)
1373 ret
= scsi_setup_blk_pc_cmnd(sdev
, req
);
1374 return scsi_prep_return(q
, req
, ret
);
1378 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1381 * Called with the queue_lock held.
1383 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1384 struct scsi_device
*sdev
)
1386 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1388 * unblock after device_blocked iterates to zero
1390 if (--sdev
->device_blocked
== 0) {
1392 sdev_printk(KERN_INFO
, sdev
,
1393 "unblocking device at zero depth\n"));
1399 if (scsi_device_is_busy(sdev
))
1407 * scsi_target_queue_ready: checks if there we can send commands to target
1408 * @sdev: scsi device on starget to check.
1410 * Called with the host lock held.
1412 static inline int scsi_target_queue_ready(struct Scsi_Host
*shost
,
1413 struct scsi_device
*sdev
)
1415 struct scsi_target
*starget
= scsi_target(sdev
);
1417 if (starget
->single_lun
) {
1418 if (starget
->starget_sdev_user
&&
1419 starget
->starget_sdev_user
!= sdev
)
1421 starget
->starget_sdev_user
= sdev
;
1424 if (starget
->target_busy
== 0 && starget
->target_blocked
) {
1426 * unblock after target_blocked iterates to zero
1428 if (--starget
->target_blocked
== 0) {
1429 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO
, starget
,
1430 "unblocking target at zero depth\n"));
1432 blk_plug_device(sdev
->request_queue
);
1437 if (scsi_target_is_busy(starget
)) {
1438 if (list_empty(&sdev
->starved_entry
)) {
1439 list_add_tail(&sdev
->starved_entry
,
1440 &shost
->starved_list
);
1445 /* We're OK to process the command, so we can't be starved */
1446 if (!list_empty(&sdev
->starved_entry
))
1447 list_del_init(&sdev
->starved_entry
);
1452 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1453 * return 0. We must end up running the queue again whenever 0 is
1454 * returned, else IO can hang.
1456 * Called with host_lock held.
1458 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1459 struct Scsi_Host
*shost
,
1460 struct scsi_device
*sdev
)
1462 if (scsi_host_in_recovery(shost
))
1464 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1466 * unblock after host_blocked iterates to zero
1468 if (--shost
->host_blocked
== 0) {
1470 printk("scsi%d unblocking host at zero depth\n",
1476 if (scsi_host_is_busy(shost
)) {
1477 if (list_empty(&sdev
->starved_entry
))
1478 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1482 /* We're OK to process the command, so we can't be starved */
1483 if (!list_empty(&sdev
->starved_entry
))
1484 list_del_init(&sdev
->starved_entry
);
1490 * Busy state exporting function for request stacking drivers.
1492 * For efficiency, no lock is taken to check the busy state of
1493 * shost/starget/sdev, since the returned value is not guaranteed and
1494 * may be changed after request stacking drivers call the function,
1495 * regardless of taking lock or not.
1497 * When scsi can't dispatch I/Os anymore and needs to kill I/Os
1498 * (e.g. !sdev), scsi needs to return 'not busy'.
1499 * Otherwise, request stacking drivers may hold requests forever.
1501 static int scsi_lld_busy(struct request_queue
*q
)
1503 struct scsi_device
*sdev
= q
->queuedata
;
1504 struct Scsi_Host
*shost
;
1505 struct scsi_target
*starget
;
1511 starget
= scsi_target(sdev
);
1513 if (scsi_host_in_recovery(shost
) || scsi_host_is_busy(shost
) ||
1514 scsi_target_is_busy(starget
) || scsi_device_is_busy(sdev
))
1521 * Kill a request for a dead device
1523 static void scsi_kill_request(struct request
*req
, struct request_queue
*q
)
1525 struct scsi_cmnd
*cmd
= req
->special
;
1526 struct scsi_device
*sdev
= cmd
->device
;
1527 struct scsi_target
*starget
= scsi_target(sdev
);
1528 struct Scsi_Host
*shost
= sdev
->host
;
1530 blkdev_dequeue_request(req
);
1532 if (unlikely(cmd
== NULL
)) {
1533 printk(KERN_CRIT
"impossible request in %s.\n",
1538 scsi_init_cmd_errh(cmd
);
1539 cmd
->result
= DID_NO_CONNECT
<< 16;
1540 atomic_inc(&cmd
->device
->iorequest_cnt
);
1543 * SCSI request completion path will do scsi_device_unbusy(),
1544 * bump busy counts. To bump the counters, we need to dance
1545 * with the locks as normal issue path does.
1547 sdev
->device_busy
++;
1548 spin_unlock(sdev
->request_queue
->queue_lock
);
1549 spin_lock(shost
->host_lock
);
1551 starget
->target_busy
++;
1552 spin_unlock(shost
->host_lock
);
1553 spin_lock(sdev
->request_queue
->queue_lock
);
1555 blk_complete_request(req
);
1558 static void scsi_softirq_done(struct request
*rq
)
1560 struct scsi_cmnd
*cmd
= rq
->special
;
1561 unsigned long wait_for
= (cmd
->allowed
+ 1) * rq
->timeout
;
1564 INIT_LIST_HEAD(&cmd
->eh_entry
);
1567 * Set the serial numbers back to zero
1569 cmd
->serial_number
= 0;
1571 atomic_inc(&cmd
->device
->iodone_cnt
);
1573 atomic_inc(&cmd
->device
->ioerr_cnt
);
1575 disposition
= scsi_decide_disposition(cmd
);
1576 if (disposition
!= SUCCESS
&&
1577 time_before(cmd
->jiffies_at_alloc
+ wait_for
, jiffies
)) {
1578 sdev_printk(KERN_ERR
, cmd
->device
,
1579 "timing out command, waited %lus\n",
1581 disposition
= SUCCESS
;
1584 scsi_log_completion(cmd
, disposition
);
1586 switch (disposition
) {
1588 scsi_finish_command(cmd
);
1591 scsi_queue_insert(cmd
, SCSI_MLQUEUE_EH_RETRY
);
1593 case ADD_TO_MLQUEUE
:
1594 scsi_queue_insert(cmd
, SCSI_MLQUEUE_DEVICE_BUSY
);
1597 if (!scsi_eh_scmd_add(cmd
, 0))
1598 scsi_finish_command(cmd
);
1603 * Function: scsi_request_fn()
1605 * Purpose: Main strategy routine for SCSI.
1607 * Arguments: q - Pointer to actual queue.
1611 * Lock status: IO request lock assumed to be held when called.
1613 static void scsi_request_fn(struct request_queue
*q
)
1615 struct scsi_device
*sdev
= q
->queuedata
;
1616 struct Scsi_Host
*shost
;
1617 struct scsi_cmnd
*cmd
;
1618 struct request
*req
;
1621 printk("scsi: killing requests for dead queue\n");
1622 while ((req
= elv_next_request(q
)) != NULL
)
1623 scsi_kill_request(req
, q
);
1627 if(!get_device(&sdev
->sdev_gendev
))
1628 /* We must be tearing the block queue down already */
1632 * To start with, we keep looping until the queue is empty, or until
1633 * the host is no longer able to accept any more requests.
1636 while (!blk_queue_plugged(q
)) {
1639 * get next queueable request. We do this early to make sure
1640 * that the request is fully prepared even if we cannot
1643 req
= elv_next_request(q
);
1644 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1647 if (unlikely(!scsi_device_online(sdev
))) {
1648 sdev_printk(KERN_ERR
, sdev
,
1649 "rejecting I/O to offline device\n");
1650 scsi_kill_request(req
, q
);
1656 * Remove the request from the request list.
1658 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1659 blkdev_dequeue_request(req
);
1660 sdev
->device_busy
++;
1662 spin_unlock(q
->queue_lock
);
1664 if (unlikely(cmd
== NULL
)) {
1665 printk(KERN_CRIT
"impossible request in %s.\n"
1666 "please mail a stack trace to "
1667 "linux-scsi@vger.kernel.org\n",
1669 blk_dump_rq_flags(req
, "foo");
1672 spin_lock(shost
->host_lock
);
1675 * We hit this when the driver is using a host wide
1676 * tag map. For device level tag maps the queue_depth check
1677 * in the device ready fn would prevent us from trying
1678 * to allocate a tag. Since the map is a shared host resource
1679 * we add the dev to the starved list so it eventually gets
1680 * a run when a tag is freed.
1682 if (blk_queue_tagged(q
) && !blk_rq_tagged(req
)) {
1683 if (list_empty(&sdev
->starved_entry
))
1684 list_add_tail(&sdev
->starved_entry
,
1685 &shost
->starved_list
);
1689 if (!scsi_target_queue_ready(shost
, sdev
))
1692 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1695 scsi_target(sdev
)->target_busy
++;
1699 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1700 * take the lock again.
1702 spin_unlock_irq(shost
->host_lock
);
1705 * Finally, initialize any error handling parameters, and set up
1706 * the timers for timeouts.
1708 scsi_init_cmd_errh(cmd
);
1711 * Dispatch the command to the low-level driver.
1713 rtn
= scsi_dispatch_cmd(cmd
);
1714 spin_lock_irq(q
->queue_lock
);
1716 /* we're refusing the command; because of
1717 * the way locks get dropped, we need to
1718 * check here if plugging is required */
1719 if(sdev
->device_busy
== 0)
1729 spin_unlock_irq(shost
->host_lock
);
1732 * lock q, handle tag, requeue req, and decrement device_busy. We
1733 * must return with queue_lock held.
1735 * Decrementing device_busy without checking it is OK, as all such
1736 * cases (host limits or settings) should run the queue at some
1739 spin_lock_irq(q
->queue_lock
);
1740 blk_requeue_request(q
, req
);
1741 sdev
->device_busy
--;
1742 if(sdev
->device_busy
== 0)
1745 /* must be careful here...if we trigger the ->remove() function
1746 * we cannot be holding the q lock */
1747 spin_unlock_irq(q
->queue_lock
);
1748 put_device(&sdev
->sdev_gendev
);
1749 spin_lock_irq(q
->queue_lock
);
1752 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1754 struct device
*host_dev
;
1755 u64 bounce_limit
= 0xffffffff;
1757 if (shost
->unchecked_isa_dma
)
1758 return BLK_BOUNCE_ISA
;
1760 * Platforms with virtual-DMA translation
1761 * hardware have no practical limit.
1763 if (!PCI_DMA_BUS_IS_PHYS
)
1764 return BLK_BOUNCE_ANY
;
1766 host_dev
= scsi_get_device(shost
);
1767 if (host_dev
&& host_dev
->dma_mask
)
1768 bounce_limit
= *host_dev
->dma_mask
;
1770 return bounce_limit
;
1772 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1774 struct request_queue
*__scsi_alloc_queue(struct Scsi_Host
*shost
,
1775 request_fn_proc
*request_fn
)
1777 struct request_queue
*q
;
1778 struct device
*dev
= shost
->shost_gendev
.parent
;
1780 q
= blk_init_queue(request_fn
, NULL
);
1785 * this limit is imposed by hardware restrictions
1787 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1788 blk_queue_max_phys_segments(q
, SCSI_MAX_SG_CHAIN_SEGMENTS
);
1790 blk_queue_max_sectors(q
, shost
->max_sectors
);
1791 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1792 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1793 dma_set_seg_boundary(dev
, shost
->dma_boundary
);
1795 blk_queue_max_segment_size(q
, dma_get_max_seg_size(dev
));
1797 /* New queue, no concurrency on queue_flags */
1798 if (!shost
->use_clustering
)
1799 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER
, q
);
1802 * set a reasonable default alignment on word boundaries: the
1803 * host and device may alter it using
1804 * blk_queue_update_dma_alignment() later.
1806 blk_queue_dma_alignment(q
, 0x03);
1810 EXPORT_SYMBOL(__scsi_alloc_queue
);
1812 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1814 struct request_queue
*q
;
1816 q
= __scsi_alloc_queue(sdev
->host
, scsi_request_fn
);
1820 blk_queue_prep_rq(q
, scsi_prep_fn
);
1821 blk_queue_softirq_done(q
, scsi_softirq_done
);
1822 blk_queue_rq_timed_out(q
, scsi_times_out
);
1823 blk_queue_lld_busy(q
, scsi_lld_busy
);
1827 void scsi_free_queue(struct request_queue
*q
)
1829 blk_cleanup_queue(q
);
1833 * Function: scsi_block_requests()
1835 * Purpose: Utility function used by low-level drivers to prevent further
1836 * commands from being queued to the device.
1838 * Arguments: shost - Host in question
1842 * Lock status: No locks are assumed held.
1844 * Notes: There is no timer nor any other means by which the requests
1845 * get unblocked other than the low-level driver calling
1846 * scsi_unblock_requests().
1848 void scsi_block_requests(struct Scsi_Host
*shost
)
1850 shost
->host_self_blocked
= 1;
1852 EXPORT_SYMBOL(scsi_block_requests
);
1855 * Function: scsi_unblock_requests()
1857 * Purpose: Utility function used by low-level drivers to allow further
1858 * commands from being queued to the device.
1860 * Arguments: shost - Host in question
1864 * Lock status: No locks are assumed held.
1866 * Notes: There is no timer nor any other means by which the requests
1867 * get unblocked other than the low-level driver calling
1868 * scsi_unblock_requests().
1870 * This is done as an API function so that changes to the
1871 * internals of the scsi mid-layer won't require wholesale
1872 * changes to drivers that use this feature.
1874 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1876 shost
->host_self_blocked
= 0;
1877 scsi_run_host_queues(shost
);
1879 EXPORT_SYMBOL(scsi_unblock_requests
);
1881 int __init
scsi_init_queue(void)
1885 scsi_io_context_cache
= kmem_cache_create("scsi_io_context",
1886 sizeof(struct scsi_io_context
),
1888 if (!scsi_io_context_cache
) {
1889 printk(KERN_ERR
"SCSI: can't init scsi io context cache\n");
1893 scsi_sdb_cache
= kmem_cache_create("scsi_data_buffer",
1894 sizeof(struct scsi_data_buffer
),
1896 if (!scsi_sdb_cache
) {
1897 printk(KERN_ERR
"SCSI: can't init scsi sdb cache\n");
1898 goto cleanup_io_context
;
1901 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1902 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1903 int size
= sgp
->size
* sizeof(struct scatterlist
);
1905 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1906 SLAB_HWCACHE_ALIGN
, NULL
);
1908 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1913 sgp
->pool
= mempool_create_slab_pool(SG_MEMPOOL_SIZE
,
1916 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1925 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1926 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1928 mempool_destroy(sgp
->pool
);
1930 kmem_cache_destroy(sgp
->slab
);
1932 kmem_cache_destroy(scsi_sdb_cache
);
1934 kmem_cache_destroy(scsi_io_context_cache
);
1939 void scsi_exit_queue(void)
1943 kmem_cache_destroy(scsi_io_context_cache
);
1944 kmem_cache_destroy(scsi_sdb_cache
);
1946 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1947 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1948 mempool_destroy(sgp
->pool
);
1949 kmem_cache_destroy(sgp
->slab
);
1954 * scsi_mode_select - issue a mode select
1955 * @sdev: SCSI device to be queried
1956 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1957 * @sp: Save page bit (0 == don't save, 1 == save)
1958 * @modepage: mode page being requested
1959 * @buffer: request buffer (may not be smaller than eight bytes)
1960 * @len: length of request buffer.
1961 * @timeout: command timeout
1962 * @retries: number of retries before failing
1963 * @data: returns a structure abstracting the mode header data
1964 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1965 * must be SCSI_SENSE_BUFFERSIZE big.
1967 * Returns zero if successful; negative error number or scsi
1972 scsi_mode_select(struct scsi_device
*sdev
, int pf
, int sp
, int modepage
,
1973 unsigned char *buffer
, int len
, int timeout
, int retries
,
1974 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
)
1976 unsigned char cmd
[10];
1977 unsigned char *real_buffer
;
1980 memset(cmd
, 0, sizeof(cmd
));
1981 cmd
[1] = (pf
? 0x10 : 0) | (sp
? 0x01 : 0);
1983 if (sdev
->use_10_for_ms
) {
1986 real_buffer
= kmalloc(8 + len
, GFP_KERNEL
);
1989 memcpy(real_buffer
+ 8, buffer
, len
);
1993 real_buffer
[2] = data
->medium_type
;
1994 real_buffer
[3] = data
->device_specific
;
1995 real_buffer
[4] = data
->longlba
? 0x01 : 0;
1997 real_buffer
[6] = data
->block_descriptor_length
>> 8;
1998 real_buffer
[7] = data
->block_descriptor_length
;
2000 cmd
[0] = MODE_SELECT_10
;
2004 if (len
> 255 || data
->block_descriptor_length
> 255 ||
2008 real_buffer
= kmalloc(4 + len
, GFP_KERNEL
);
2011 memcpy(real_buffer
+ 4, buffer
, len
);
2014 real_buffer
[1] = data
->medium_type
;
2015 real_buffer
[2] = data
->device_specific
;
2016 real_buffer
[3] = data
->block_descriptor_length
;
2019 cmd
[0] = MODE_SELECT
;
2023 ret
= scsi_execute_req(sdev
, cmd
, DMA_TO_DEVICE
, real_buffer
, len
,
2024 sshdr
, timeout
, retries
, NULL
);
2028 EXPORT_SYMBOL_GPL(scsi_mode_select
);
2031 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2032 * @sdev: SCSI device to be queried
2033 * @dbd: set if mode sense will allow block descriptors to be returned
2034 * @modepage: mode page being requested
2035 * @buffer: request buffer (may not be smaller than eight bytes)
2036 * @len: length of request buffer.
2037 * @timeout: command timeout
2038 * @retries: number of retries before failing
2039 * @data: returns a structure abstracting the mode header data
2040 * @sshdr: place to put sense data (or NULL if no sense to be collected).
2041 * must be SCSI_SENSE_BUFFERSIZE big.
2043 * Returns zero if unsuccessful, or the header offset (either 4
2044 * or 8 depending on whether a six or ten byte command was
2045 * issued) if successful.
2048 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
2049 unsigned char *buffer
, int len
, int timeout
, int retries
,
2050 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
)
2052 unsigned char cmd
[12];
2056 struct scsi_sense_hdr my_sshdr
;
2058 memset(data
, 0, sizeof(*data
));
2059 memset(&cmd
[0], 0, 12);
2060 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
2063 /* caller might not be interested in sense, but we need it */
2068 use_10_for_ms
= sdev
->use_10_for_ms
;
2070 if (use_10_for_ms
) {
2074 cmd
[0] = MODE_SENSE_10
;
2081 cmd
[0] = MODE_SENSE
;
2086 memset(buffer
, 0, len
);
2088 result
= scsi_execute_req(sdev
, cmd
, DMA_FROM_DEVICE
, buffer
, len
,
2089 sshdr
, timeout
, retries
, NULL
);
2091 /* This code looks awful: what it's doing is making sure an
2092 * ILLEGAL REQUEST sense return identifies the actual command
2093 * byte as the problem. MODE_SENSE commands can return
2094 * ILLEGAL REQUEST if the code page isn't supported */
2096 if (use_10_for_ms
&& !scsi_status_is_good(result
) &&
2097 (driver_byte(result
) & DRIVER_SENSE
)) {
2098 if (scsi_sense_valid(sshdr
)) {
2099 if ((sshdr
->sense_key
== ILLEGAL_REQUEST
) &&
2100 (sshdr
->asc
== 0x20) && (sshdr
->ascq
== 0)) {
2102 * Invalid command operation code
2104 sdev
->use_10_for_ms
= 0;
2110 if(scsi_status_is_good(result
)) {
2111 if (unlikely(buffer
[0] == 0x86 && buffer
[1] == 0x0b &&
2112 (modepage
== 6 || modepage
== 8))) {
2113 /* Initio breakage? */
2116 data
->medium_type
= 0;
2117 data
->device_specific
= 0;
2119 data
->block_descriptor_length
= 0;
2120 } else if(use_10_for_ms
) {
2121 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
2122 data
->medium_type
= buffer
[2];
2123 data
->device_specific
= buffer
[3];
2124 data
->longlba
= buffer
[4] & 0x01;
2125 data
->block_descriptor_length
= buffer
[6]*256
2128 data
->length
= buffer
[0] + 1;
2129 data
->medium_type
= buffer
[1];
2130 data
->device_specific
= buffer
[2];
2131 data
->block_descriptor_length
= buffer
[3];
2133 data
->header_length
= header_length
;
2138 EXPORT_SYMBOL(scsi_mode_sense
);
2141 * scsi_test_unit_ready - test if unit is ready
2142 * @sdev: scsi device to change the state of.
2143 * @timeout: command timeout
2144 * @retries: number of retries before failing
2145 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2146 * returning sense. Make sure that this is cleared before passing
2149 * Returns zero if unsuccessful or an error if TUR failed. For
2150 * removable media, a return of NOT_READY or UNIT_ATTENTION is
2151 * translated to success, with the ->changed flag updated.
2154 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
,
2155 struct scsi_sense_hdr
*sshdr_external
)
2158 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
2160 struct scsi_sense_hdr
*sshdr
;
2163 if (!sshdr_external
)
2164 sshdr
= kzalloc(sizeof(*sshdr
), GFP_KERNEL
);
2166 sshdr
= sshdr_external
;
2168 /* try to eat the UNIT_ATTENTION if there are enough retries */
2170 result
= scsi_execute_req(sdev
, cmd
, DMA_NONE
, NULL
, 0, sshdr
,
2171 timeout
, retries
, NULL
);
2172 if (sdev
->removable
&& scsi_sense_valid(sshdr
) &&
2173 sshdr
->sense_key
== UNIT_ATTENTION
)
2175 } while (scsi_sense_valid(sshdr
) &&
2176 sshdr
->sense_key
== UNIT_ATTENTION
&& --retries
);
2179 /* could not allocate sense buffer, so can't process it */
2182 if (sdev
->removable
&& scsi_sense_valid(sshdr
) &&
2183 (sshdr
->sense_key
== UNIT_ATTENTION
||
2184 sshdr
->sense_key
== NOT_READY
)) {
2188 if (!sshdr_external
)
2192 EXPORT_SYMBOL(scsi_test_unit_ready
);
2195 * scsi_device_set_state - Take the given device through the device state model.
2196 * @sdev: scsi device to change the state of.
2197 * @state: state to change to.
2199 * Returns zero if unsuccessful or an error if the requested
2200 * transition is illegal.
2203 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
2205 enum scsi_device_state oldstate
= sdev
->sdev_state
;
2207 if (state
== oldstate
)
2213 case SDEV_CREATED_BLOCK
:
2257 case SDEV_CREATED_BLOCK
:
2264 case SDEV_CREATED_BLOCK
:
2299 sdev
->sdev_state
= state
;
2303 SCSI_LOG_ERROR_RECOVERY(1,
2304 sdev_printk(KERN_ERR
, sdev
,
2305 "Illegal state transition %s->%s\n",
2306 scsi_device_state_name(oldstate
),
2307 scsi_device_state_name(state
))
2311 EXPORT_SYMBOL(scsi_device_set_state
);
2314 * sdev_evt_emit - emit a single SCSI device uevent
2315 * @sdev: associated SCSI device
2316 * @evt: event to emit
2318 * Send a single uevent (scsi_event) to the associated scsi_device.
2320 static void scsi_evt_emit(struct scsi_device
*sdev
, struct scsi_event
*evt
)
2325 switch (evt
->evt_type
) {
2326 case SDEV_EVT_MEDIA_CHANGE
:
2327 envp
[idx
++] = "SDEV_MEDIA_CHANGE=1";
2337 kobject_uevent_env(&sdev
->sdev_gendev
.kobj
, KOBJ_CHANGE
, envp
);
2341 * sdev_evt_thread - send a uevent for each scsi event
2342 * @work: work struct for scsi_device
2344 * Dispatch queued events to their associated scsi_device kobjects
2347 void scsi_evt_thread(struct work_struct
*work
)
2349 struct scsi_device
*sdev
;
2350 LIST_HEAD(event_list
);
2352 sdev
= container_of(work
, struct scsi_device
, event_work
);
2355 struct scsi_event
*evt
;
2356 struct list_head
*this, *tmp
;
2357 unsigned long flags
;
2359 spin_lock_irqsave(&sdev
->list_lock
, flags
);
2360 list_splice_init(&sdev
->event_list
, &event_list
);
2361 spin_unlock_irqrestore(&sdev
->list_lock
, flags
);
2363 if (list_empty(&event_list
))
2366 list_for_each_safe(this, tmp
, &event_list
) {
2367 evt
= list_entry(this, struct scsi_event
, node
);
2368 list_del(&evt
->node
);
2369 scsi_evt_emit(sdev
, evt
);
2376 * sdev_evt_send - send asserted event to uevent thread
2377 * @sdev: scsi_device event occurred on
2378 * @evt: event to send
2380 * Assert scsi device event asynchronously.
2382 void sdev_evt_send(struct scsi_device
*sdev
, struct scsi_event
*evt
)
2384 unsigned long flags
;
2387 /* FIXME: currently this check eliminates all media change events
2388 * for polled devices. Need to update to discriminate between AN
2389 * and polled events */
2390 if (!test_bit(evt
->evt_type
, sdev
->supported_events
)) {
2396 spin_lock_irqsave(&sdev
->list_lock
, flags
);
2397 list_add_tail(&evt
->node
, &sdev
->event_list
);
2398 schedule_work(&sdev
->event_work
);
2399 spin_unlock_irqrestore(&sdev
->list_lock
, flags
);
2401 EXPORT_SYMBOL_GPL(sdev_evt_send
);
2404 * sdev_evt_alloc - allocate a new scsi event
2405 * @evt_type: type of event to allocate
2406 * @gfpflags: GFP flags for allocation
2408 * Allocates and returns a new scsi_event.
2410 struct scsi_event
*sdev_evt_alloc(enum scsi_device_event evt_type
,
2413 struct scsi_event
*evt
= kzalloc(sizeof(struct scsi_event
), gfpflags
);
2417 evt
->evt_type
= evt_type
;
2418 INIT_LIST_HEAD(&evt
->node
);
2420 /* evt_type-specific initialization, if any */
2422 case SDEV_EVT_MEDIA_CHANGE
:
2430 EXPORT_SYMBOL_GPL(sdev_evt_alloc
);
2433 * sdev_evt_send_simple - send asserted event to uevent thread
2434 * @sdev: scsi_device event occurred on
2435 * @evt_type: type of event to send
2436 * @gfpflags: GFP flags for allocation
2438 * Assert scsi device event asynchronously, given an event type.
2440 void sdev_evt_send_simple(struct scsi_device
*sdev
,
2441 enum scsi_device_event evt_type
, gfp_t gfpflags
)
2443 struct scsi_event
*evt
= sdev_evt_alloc(evt_type
, gfpflags
);
2445 sdev_printk(KERN_ERR
, sdev
, "event %d eaten due to OOM\n",
2450 sdev_evt_send(sdev
, evt
);
2452 EXPORT_SYMBOL_GPL(sdev_evt_send_simple
);
2455 * scsi_device_quiesce - Block user issued commands.
2456 * @sdev: scsi device to quiesce.
2458 * This works by trying to transition to the SDEV_QUIESCE state
2459 * (which must be a legal transition). When the device is in this
2460 * state, only special requests will be accepted, all others will
2461 * be deferred. Since special requests may also be requeued requests,
2462 * a successful return doesn't guarantee the device will be
2463 * totally quiescent.
2465 * Must be called with user context, may sleep.
2467 * Returns zero if unsuccessful or an error if not.
2470 scsi_device_quiesce(struct scsi_device
*sdev
)
2472 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
2476 scsi_run_queue(sdev
->request_queue
);
2477 while (sdev
->device_busy
) {
2478 msleep_interruptible(200);
2479 scsi_run_queue(sdev
->request_queue
);
2483 EXPORT_SYMBOL(scsi_device_quiesce
);
2486 * scsi_device_resume - Restart user issued commands to a quiesced device.
2487 * @sdev: scsi device to resume.
2489 * Moves the device from quiesced back to running and restarts the
2492 * Must be called with user context, may sleep.
2495 scsi_device_resume(struct scsi_device
*sdev
)
2497 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
2499 scsi_run_queue(sdev
->request_queue
);
2501 EXPORT_SYMBOL(scsi_device_resume
);
2504 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
2506 scsi_device_quiesce(sdev
);
2510 scsi_target_quiesce(struct scsi_target
*starget
)
2512 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
2514 EXPORT_SYMBOL(scsi_target_quiesce
);
2517 device_resume_fn(struct scsi_device
*sdev
, void *data
)
2519 scsi_device_resume(sdev
);
2523 scsi_target_resume(struct scsi_target
*starget
)
2525 starget_for_each_device(starget
, NULL
, device_resume_fn
);
2527 EXPORT_SYMBOL(scsi_target_resume
);
2530 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2531 * @sdev: device to block
2533 * Block request made by scsi lld's to temporarily stop all
2534 * scsi commands on the specified device. Called from interrupt
2535 * or normal process context.
2537 * Returns zero if successful or error if not
2540 * This routine transitions the device to the SDEV_BLOCK state
2541 * (which must be a legal transition). When the device is in this
2542 * state, all commands are deferred until the scsi lld reenables
2543 * the device with scsi_device_unblock or device_block_tmo fires.
2544 * This routine assumes the host_lock is held on entry.
2547 scsi_internal_device_block(struct scsi_device
*sdev
)
2549 struct request_queue
*q
= sdev
->request_queue
;
2550 unsigned long flags
;
2553 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
2555 err
= scsi_device_set_state(sdev
, SDEV_CREATED_BLOCK
);
2562 * The device has transitioned to SDEV_BLOCK. Stop the
2563 * block layer from calling the midlayer with this device's
2566 spin_lock_irqsave(q
->queue_lock
, flags
);
2568 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2572 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
2575 * scsi_internal_device_unblock - resume a device after a block request
2576 * @sdev: device to resume
2578 * Called by scsi lld's or the midlayer to restart the device queue
2579 * for the previously suspended scsi device. Called from interrupt or
2580 * normal process context.
2582 * Returns zero if successful or error if not.
2585 * This routine transitions the device to the SDEV_RUNNING state
2586 * (which must be a legal transition) allowing the midlayer to
2587 * goose the queue for this device. This routine assumes the
2588 * host_lock is held upon entry.
2591 scsi_internal_device_unblock(struct scsi_device
*sdev
)
2593 struct request_queue
*q
= sdev
->request_queue
;
2595 unsigned long flags
;
2598 * Try to transition the scsi device to SDEV_RUNNING
2599 * and goose the device queue if successful.
2601 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
2603 err
= scsi_device_set_state(sdev
, SDEV_CREATED
);
2609 spin_lock_irqsave(q
->queue_lock
, flags
);
2611 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2615 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
2618 device_block(struct scsi_device
*sdev
, void *data
)
2620 scsi_internal_device_block(sdev
);
2624 target_block(struct device
*dev
, void *data
)
2626 if (scsi_is_target_device(dev
))
2627 starget_for_each_device(to_scsi_target(dev
), NULL
,
2633 scsi_target_block(struct device
*dev
)
2635 if (scsi_is_target_device(dev
))
2636 starget_for_each_device(to_scsi_target(dev
), NULL
,
2639 device_for_each_child(dev
, NULL
, target_block
);
2641 EXPORT_SYMBOL_GPL(scsi_target_block
);
2644 device_unblock(struct scsi_device
*sdev
, void *data
)
2646 scsi_internal_device_unblock(sdev
);
2650 target_unblock(struct device
*dev
, void *data
)
2652 if (scsi_is_target_device(dev
))
2653 starget_for_each_device(to_scsi_target(dev
), NULL
,
2659 scsi_target_unblock(struct device
*dev
)
2661 if (scsi_is_target_device(dev
))
2662 starget_for_each_device(to_scsi_target(dev
), NULL
,
2665 device_for_each_child(dev
, NULL
, target_unblock
);
2667 EXPORT_SYMBOL_GPL(scsi_target_unblock
);
2670 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2671 * @sgl: scatter-gather list
2672 * @sg_count: number of segments in sg
2673 * @offset: offset in bytes into sg, on return offset into the mapped area
2674 * @len: bytes to map, on return number of bytes mapped
2676 * Returns virtual address of the start of the mapped page
2678 void *scsi_kmap_atomic_sg(struct scatterlist
*sgl
, int sg_count
,
2679 size_t *offset
, size_t *len
)
2682 size_t sg_len
= 0, len_complete
= 0;
2683 struct scatterlist
*sg
;
2686 WARN_ON(!irqs_disabled());
2688 for_each_sg(sgl
, sg
, sg_count
, i
) {
2689 len_complete
= sg_len
; /* Complete sg-entries */
2690 sg_len
+= sg
->length
;
2691 if (sg_len
> *offset
)
2695 if (unlikely(i
== sg_count
)) {
2696 printk(KERN_ERR
"%s: Bytes in sg: %zu, requested offset %zu, "
2698 __func__
, sg_len
, *offset
, sg_count
);
2703 /* Offset starting from the beginning of first page in this sg-entry */
2704 *offset
= *offset
- len_complete
+ sg
->offset
;
2706 /* Assumption: contiguous pages can be accessed as "page + i" */
2707 page
= nth_page(sg_page(sg
), (*offset
>> PAGE_SHIFT
));
2708 *offset
&= ~PAGE_MASK
;
2710 /* Bytes in this sg-entry from *offset to the end of the page */
2711 sg_len
= PAGE_SIZE
- *offset
;
2715 return kmap_atomic(page
, KM_BIO_SRC_IRQ
);
2717 EXPORT_SYMBOL(scsi_kmap_atomic_sg
);
2720 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2721 * @virt: virtual address to be unmapped
2723 void scsi_kunmap_atomic_sg(void *virt
)
2725 kunmap_atomic(virt
, KM_BIO_SRC_IRQ
);
2727 EXPORT_SYMBOL(scsi_kunmap_atomic_sg
);