2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/completion.h>
13 #include <linux/kernel.h>
14 #include <linux/mempool.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/pci.h>
18 #include <linux/delay.h>
20 #include <scsi/scsi.h>
21 #include <scsi/scsi_dbg.h>
22 #include <scsi/scsi_device.h>
23 #include <scsi/scsi_driver.h>
24 #include <scsi/scsi_eh.h>
25 #include <scsi/scsi_host.h>
26 #include <scsi/scsi_request.h>
28 #include "scsi_priv.h"
29 #include "scsi_logging.h"
32 #define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
33 #define SG_MEMPOOL_SIZE 32
35 struct scsi_host_sg_pool
{
42 #if (SCSI_MAX_PHYS_SEGMENTS < 32)
43 #error SCSI_MAX_PHYS_SEGMENTS is too small
46 #define SP(x) { x, "sgpool-" #x }
47 static struct scsi_host_sg_pool scsi_sg_pools
[] = {
51 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
53 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
55 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
57 #if (SCSI_MAX_PHYS_SEGMENTS > 256)
58 #error SCSI_MAX_PHYS_SEGMENTS is too large
66 static void scsi_run_queue(struct request_queue
*q
);
69 * Function: scsi_unprep_request()
71 * Purpose: Remove all preparation done for a request, including its
72 * associated scsi_cmnd, so that it can be requeued.
74 * Arguments: req - request to unprepare
76 * Lock status: Assumed that no locks are held upon entry.
80 static void scsi_unprep_request(struct request
*req
)
82 struct scsi_cmnd
*cmd
= req
->special
;
84 req
->flags
&= ~REQ_DONTPREP
;
85 req
->special
= (req
->flags
& REQ_SPECIAL
) ? cmd
->sc_request
: NULL
;
87 scsi_put_command(cmd
);
91 * Function: scsi_queue_insert()
93 * Purpose: Insert a command in the midlevel queue.
95 * Arguments: cmd - command that we are adding to queue.
96 * reason - why we are inserting command to queue.
98 * Lock status: Assumed that lock is not held upon entry.
102 * Notes: We do this for one of two cases. Either the host is busy
103 * and it cannot accept any more commands for the time being,
104 * or the device returned QUEUE_FULL and can accept no more
106 * Notes: This could be called either from an interrupt context or a
107 * normal process context.
109 int scsi_queue_insert(struct scsi_cmnd
*cmd
, int reason
)
111 struct Scsi_Host
*host
= cmd
->device
->host
;
112 struct scsi_device
*device
= cmd
->device
;
113 struct request_queue
*q
= device
->request_queue
;
117 printk("Inserting command %p into mlqueue\n", cmd
));
120 * Set the appropriate busy bit for the device/host.
122 * If the host/device isn't busy, assume that something actually
123 * completed, and that we should be able to queue a command now.
125 * Note that the prior mid-layer assumption that any host could
126 * always queue at least one command is now broken. The mid-layer
127 * will implement a user specifiable stall (see
128 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
129 * if a command is requeued with no other commands outstanding
130 * either for the device or for the host.
132 if (reason
== SCSI_MLQUEUE_HOST_BUSY
)
133 host
->host_blocked
= host
->max_host_blocked
;
134 else if (reason
== SCSI_MLQUEUE_DEVICE_BUSY
)
135 device
->device_blocked
= device
->max_device_blocked
;
138 * Decrement the counters, since these commands are no longer
139 * active on the host/device.
141 scsi_device_unbusy(device
);
144 * Requeue this command. It will go before all other commands
145 * that are already in the queue.
147 * NOTE: there is magic here about the way the queue is plugged if
148 * we have no outstanding commands.
150 * Although we *don't* plug the queue, we call the request
151 * function. The SCSI request function detects the blocked condition
152 * and plugs the queue appropriately.
154 spin_lock_irqsave(q
->queue_lock
, flags
);
155 blk_requeue_request(q
, cmd
->request
);
156 spin_unlock_irqrestore(q
->queue_lock
, flags
);
164 * Function: scsi_do_req
166 * Purpose: Queue a SCSI request
168 * Arguments: sreq - command descriptor.
169 * cmnd - actual SCSI command to be performed.
170 * buffer - data buffer.
171 * bufflen - size of data buffer.
172 * done - completion function to be run.
173 * timeout - how long to let it run before timeout.
174 * retries - number of retries we allow.
176 * Lock status: No locks held upon entry.
180 * Notes: This function is only used for queueing requests for things
181 * like ioctls and character device requests - this is because
182 * we essentially just inject a request into the queue for the
185 * In order to support the scsi_device_quiesce function, we
186 * now inject requests on the *head* of the device queue
187 * rather than the tail.
189 void scsi_do_req(struct scsi_request
*sreq
, const void *cmnd
,
190 void *buffer
, unsigned bufflen
,
191 void (*done
)(struct scsi_cmnd
*),
192 int timeout
, int retries
)
195 * If the upper level driver is reusing these things, then
196 * we should release the low-level block now. Another one will
197 * be allocated later when this request is getting queued.
199 __scsi_release_request(sreq
);
202 * Our own function scsi_done (which marks the host as not busy,
203 * disables the timeout counter, etc) will be called by us or by the
204 * scsi_hosts[host].queuecommand() function needs to also call
205 * the completion function for the high level driver.
207 memcpy(sreq
->sr_cmnd
, cmnd
, sizeof(sreq
->sr_cmnd
));
208 sreq
->sr_bufflen
= bufflen
;
209 sreq
->sr_buffer
= buffer
;
210 sreq
->sr_allowed
= retries
;
211 sreq
->sr_done
= done
;
212 sreq
->sr_timeout_per_command
= timeout
;
214 if (sreq
->sr_cmd_len
== 0)
215 sreq
->sr_cmd_len
= COMMAND_SIZE(sreq
->sr_cmnd
[0]);
218 * head injection *required* here otherwise quiesce won't work
220 * Because users of this function are apt to reuse requests with no
221 * modification, we have to sanitise the request flags here
223 sreq
->sr_request
->flags
&= ~REQ_DONTPREP
;
224 blk_insert_request(sreq
->sr_device
->request_queue
, sreq
->sr_request
,
227 EXPORT_SYMBOL(scsi_do_req
);
230 * scsi_execute - insert request and wait for the result
233 * @data_direction: data direction
234 * @buffer: data buffer
235 * @bufflen: len of buffer
236 * @sense: optional sense buffer
237 * @timeout: request timeout in seconds
238 * @retries: number of times to retry request
239 * @flags: or into request flags;
241 * returns the req->errors value which is the the scsi_cmnd result
244 int scsi_execute(struct scsi_device
*sdev
, const unsigned char *cmd
,
245 int data_direction
, void *buffer
, unsigned bufflen
,
246 unsigned char *sense
, int timeout
, int retries
, int flags
)
249 int write
= (data_direction
== DMA_TO_DEVICE
);
250 int ret
= DRIVER_ERROR
<< 24;
252 req
= blk_get_request(sdev
->request_queue
, write
, __GFP_WAIT
);
254 if (bufflen
&& blk_rq_map_kern(sdev
->request_queue
, req
,
255 buffer
, bufflen
, __GFP_WAIT
))
258 req
->cmd_len
= COMMAND_SIZE(cmd
[0]);
259 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
262 req
->retries
= retries
;
263 req
->timeout
= timeout
;
264 req
->flags
|= flags
| REQ_BLOCK_PC
| REQ_SPECIAL
| REQ_QUIET
;
267 * head injection *required* here otherwise quiesce won't work
269 blk_execute_rq(req
->q
, NULL
, req
, 1);
273 blk_put_request(req
);
277 EXPORT_SYMBOL(scsi_execute
);
280 int scsi_execute_req(struct scsi_device
*sdev
, const unsigned char *cmd
,
281 int data_direction
, void *buffer
, unsigned bufflen
,
282 struct scsi_sense_hdr
*sshdr
, int timeout
, int retries
)
288 sense
= kmalloc(SCSI_SENSE_BUFFERSIZE
, GFP_NOIO
);
290 return DRIVER_ERROR
<< 24;
291 memset(sense
, 0, SCSI_SENSE_BUFFERSIZE
);
293 result
= scsi_execute(sdev
, cmd
, data_direction
, buffer
, bufflen
,
294 sense
, timeout
, retries
, 0);
296 scsi_normalize_sense(sense
, SCSI_SENSE_BUFFERSIZE
, sshdr
);
301 EXPORT_SYMBOL(scsi_execute_req
);
303 struct scsi_io_context
{
305 void (*done
)(void *data
, char *sense
, int result
, int resid
);
306 char sense
[SCSI_SENSE_BUFFERSIZE
];
309 static kmem_cache_t
*scsi_io_context_cache
;
311 static void scsi_end_async(struct request
*req
)
313 struct scsi_io_context
*sioc
= req
->end_io_data
;
316 sioc
->done(sioc
->data
, sioc
->sense
, req
->errors
, req
->data_len
);
318 kmem_cache_free(scsi_io_context_cache
, sioc
);
319 __blk_put_request(req
->q
, req
);
322 static int scsi_merge_bio(struct request
*rq
, struct bio
*bio
)
324 struct request_queue
*q
= rq
->q
;
326 bio
->bi_flags
&= ~(1 << BIO_SEG_VALID
);
327 if (rq_data_dir(rq
) == WRITE
)
328 bio
->bi_rw
|= (1 << BIO_RW
);
329 blk_queue_bounce(q
, &bio
);
332 blk_rq_bio_prep(q
, rq
, bio
);
333 else if (!q
->back_merge_fn(q
, rq
, bio
))
336 rq
->biotail
->bi_next
= bio
;
338 rq
->hard_nr_sectors
+= bio_sectors(bio
);
339 rq
->nr_sectors
= rq
->hard_nr_sectors
;
345 static int scsi_bi_endio(struct bio
*bio
, unsigned int bytes_done
, int error
)
355 * scsi_req_map_sg - map a scatterlist into a request
356 * @rq: request to fill
358 * @nsegs: number of elements
359 * @bufflen: len of buffer
360 * @gfp: memory allocation flags
362 * scsi_req_map_sg maps a scatterlist into a request so that the
363 * request can be sent to the block layer. We do not trust the scatterlist
364 * sent to use, as some ULDs use that struct to only organize the pages.
366 static int scsi_req_map_sg(struct request
*rq
, struct scatterlist
*sgl
,
367 int nsegs
, unsigned bufflen
, gfp_t gfp
)
369 struct request_queue
*q
= rq
->q
;
370 int nr_pages
= (bufflen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
371 unsigned int data_len
= 0, len
, bytes
, off
;
373 struct bio
*bio
= NULL
;
374 int i
, err
, nr_vecs
= 0;
376 for (i
= 0; i
< nsegs
; i
++) {
383 bytes
= min_t(unsigned int, len
, PAGE_SIZE
- off
);
386 nr_vecs
= min_t(int, BIO_MAX_PAGES
, nr_pages
);
389 bio
= bio_alloc(gfp
, nr_vecs
);
394 bio
->bi_end_io
= scsi_bi_endio
;
397 if (bio_add_pc_page(q
, bio
, page
, bytes
, off
) !=
404 if (bio
->bi_vcnt
>= nr_vecs
) {
405 err
= scsi_merge_bio(rq
, bio
);
407 bio_endio(bio
, bio
->bi_size
, 0);
419 rq
->buffer
= rq
->data
= NULL
;
420 rq
->data_len
= data_len
;
424 while ((bio
= rq
->bio
) != NULL
) {
425 rq
->bio
= bio
->bi_next
;
427 * call endio instead of bio_put incase it was bounced
429 bio_endio(bio
, bio
->bi_size
, 0);
436 * scsi_execute_async - insert request
439 * @data_direction: data direction
440 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
441 * @bufflen: len of buffer
442 * @use_sg: if buffer is a scatterlist this is the number of elements
443 * @timeout: request timeout in seconds
444 * @retries: number of times to retry request
445 * @flags: or into request flags
447 int scsi_execute_async(struct scsi_device
*sdev
, const unsigned char *cmd
,
448 int data_direction
, void *buffer
, unsigned bufflen
,
449 int use_sg
, int timeout
, int retries
, void *privdata
,
450 void (*done
)(void *, char *, int, int), gfp_t gfp
)
453 struct scsi_io_context
*sioc
;
455 int write
= (data_direction
== DMA_TO_DEVICE
);
457 sioc
= kmem_cache_alloc(scsi_io_context_cache
, gfp
);
459 return DRIVER_ERROR
<< 24;
460 memset(sioc
, 0, sizeof(*sioc
));
462 req
= blk_get_request(sdev
->request_queue
, write
, gfp
);
465 req
->flags
|= REQ_BLOCK_PC
| REQ_QUIET
;
468 err
= scsi_req_map_sg(req
, buffer
, use_sg
, bufflen
, gfp
);
470 err
= blk_rq_map_kern(req
->q
, req
, buffer
, bufflen
, gfp
);
475 req
->cmd_len
= COMMAND_SIZE(cmd
[0]);
476 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
477 req
->sense
= sioc
->sense
;
479 req
->timeout
= timeout
;
480 req
->retries
= retries
;
481 req
->end_io_data
= sioc
;
483 sioc
->data
= privdata
;
486 blk_execute_rq_nowait(req
->q
, NULL
, req
, 1, scsi_end_async
);
490 blk_put_request(req
);
493 return DRIVER_ERROR
<< 24;
495 EXPORT_SYMBOL_GPL(scsi_execute_async
);
498 * Function: scsi_init_cmd_errh()
500 * Purpose: Initialize cmd fields related to error handling.
502 * Arguments: cmd - command that is ready to be queued.
506 * Notes: This function has the job of initializing a number of
507 * fields related to error handling. Typically this will
508 * be called once for each command, as required.
510 static int scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
512 cmd
->serial_number
= 0;
514 memset(cmd
->sense_buffer
, 0, sizeof cmd
->sense_buffer
);
516 if (cmd
->cmd_len
== 0)
517 cmd
->cmd_len
= COMMAND_SIZE(cmd
->cmnd
[0]);
520 * We need saved copies of a number of fields - this is because
521 * error handling may need to overwrite these with different values
522 * to run different commands, and once error handling is complete,
523 * we will need to restore these values prior to running the actual
526 cmd
->old_use_sg
= cmd
->use_sg
;
527 cmd
->old_cmd_len
= cmd
->cmd_len
;
528 cmd
->sc_old_data_direction
= cmd
->sc_data_direction
;
529 cmd
->old_underflow
= cmd
->underflow
;
530 memcpy(cmd
->data_cmnd
, cmd
->cmnd
, sizeof(cmd
->cmnd
));
531 cmd
->buffer
= cmd
->request_buffer
;
532 cmd
->bufflen
= cmd
->request_bufflen
;
538 * Function: scsi_setup_cmd_retry()
540 * Purpose: Restore the command state for a retry
542 * Arguments: cmd - command to be restored
546 * Notes: Immediately prior to retrying a command, we need
547 * to restore certain fields that we saved above.
549 void scsi_setup_cmd_retry(struct scsi_cmnd
*cmd
)
551 memcpy(cmd
->cmnd
, cmd
->data_cmnd
, sizeof(cmd
->data_cmnd
));
552 cmd
->request_buffer
= cmd
->buffer
;
553 cmd
->request_bufflen
= cmd
->bufflen
;
554 cmd
->use_sg
= cmd
->old_use_sg
;
555 cmd
->cmd_len
= cmd
->old_cmd_len
;
556 cmd
->sc_data_direction
= cmd
->sc_old_data_direction
;
557 cmd
->underflow
= cmd
->old_underflow
;
560 void scsi_device_unbusy(struct scsi_device
*sdev
)
562 struct Scsi_Host
*shost
= sdev
->host
;
565 spin_lock_irqsave(shost
->host_lock
, flags
);
567 if (unlikely(scsi_host_in_recovery(shost
) &&
569 scsi_eh_wakeup(shost
);
570 spin_unlock(shost
->host_lock
);
571 spin_lock(sdev
->request_queue
->queue_lock
);
573 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
577 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
578 * and call blk_run_queue for all the scsi_devices on the target -
579 * including current_sdev first.
581 * Called with *no* scsi locks held.
583 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
585 struct Scsi_Host
*shost
= current_sdev
->host
;
586 struct scsi_device
*sdev
, *tmp
;
587 struct scsi_target
*starget
= scsi_target(current_sdev
);
590 spin_lock_irqsave(shost
->host_lock
, flags
);
591 starget
->starget_sdev_user
= NULL
;
592 spin_unlock_irqrestore(shost
->host_lock
, flags
);
595 * Call blk_run_queue for all LUNs on the target, starting with
596 * current_sdev. We race with others (to set starget_sdev_user),
597 * but in most cases, we will be first. Ideally, each LU on the
598 * target would get some limited time or requests on the target.
600 blk_run_queue(current_sdev
->request_queue
);
602 spin_lock_irqsave(shost
->host_lock
, flags
);
603 if (starget
->starget_sdev_user
)
605 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
606 same_target_siblings
) {
607 if (sdev
== current_sdev
)
609 if (scsi_device_get(sdev
))
612 spin_unlock_irqrestore(shost
->host_lock
, flags
);
613 blk_run_queue(sdev
->request_queue
);
614 spin_lock_irqsave(shost
->host_lock
, flags
);
616 scsi_device_put(sdev
);
619 spin_unlock_irqrestore(shost
->host_lock
, flags
);
623 * Function: scsi_run_queue()
625 * Purpose: Select a proper request queue to serve next
627 * Arguments: q - last request's queue
631 * Notes: The previous command was completely finished, start
632 * a new one if possible.
634 static void scsi_run_queue(struct request_queue
*q
)
636 struct scsi_device
*sdev
= q
->queuedata
;
637 struct Scsi_Host
*shost
= sdev
->host
;
640 if (sdev
->single_lun
)
641 scsi_single_lun_run(sdev
);
643 spin_lock_irqsave(shost
->host_lock
, flags
);
644 while (!list_empty(&shost
->starved_list
) &&
645 !shost
->host_blocked
&& !shost
->host_self_blocked
&&
646 !((shost
->can_queue
> 0) &&
647 (shost
->host_busy
>= shost
->can_queue
))) {
649 * As long as shost is accepting commands and we have
650 * starved queues, call blk_run_queue. scsi_request_fn
651 * drops the queue_lock and can add us back to the
654 * host_lock protects the starved_list and starved_entry.
655 * scsi_request_fn must get the host_lock before checking
656 * or modifying starved_list or starved_entry.
658 sdev
= list_entry(shost
->starved_list
.next
,
659 struct scsi_device
, starved_entry
);
660 list_del_init(&sdev
->starved_entry
);
661 spin_unlock_irqrestore(shost
->host_lock
, flags
);
663 blk_run_queue(sdev
->request_queue
);
665 spin_lock_irqsave(shost
->host_lock
, flags
);
666 if (unlikely(!list_empty(&sdev
->starved_entry
)))
668 * sdev lost a race, and was put back on the
669 * starved list. This is unlikely but without this
670 * in theory we could loop forever.
674 spin_unlock_irqrestore(shost
->host_lock
, flags
);
680 * Function: scsi_requeue_command()
682 * Purpose: Handle post-processing of completed commands.
684 * Arguments: q - queue to operate on
685 * cmd - command that may need to be requeued.
689 * Notes: After command completion, there may be blocks left
690 * over which weren't finished by the previous command
691 * this can be for a number of reasons - the main one is
692 * I/O errors in the middle of the request, in which case
693 * we need to request the blocks that come after the bad
695 * Notes: Upon return, cmd is a stale pointer.
697 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
699 struct request
*req
= cmd
->request
;
702 scsi_unprep_request(req
);
703 spin_lock_irqsave(q
->queue_lock
, flags
);
704 blk_requeue_request(q
, req
);
705 spin_unlock_irqrestore(q
->queue_lock
, flags
);
710 void scsi_next_command(struct scsi_cmnd
*cmd
)
712 struct scsi_device
*sdev
= cmd
->device
;
713 struct request_queue
*q
= sdev
->request_queue
;
715 /* need to hold a reference on the device before we let go of the cmd */
716 get_device(&sdev
->sdev_gendev
);
718 scsi_put_command(cmd
);
721 /* ok to remove device now */
722 put_device(&sdev
->sdev_gendev
);
725 void scsi_run_host_queues(struct Scsi_Host
*shost
)
727 struct scsi_device
*sdev
;
729 shost_for_each_device(sdev
, shost
)
730 scsi_run_queue(sdev
->request_queue
);
734 * Function: scsi_end_request()
736 * Purpose: Post-processing of completed commands (usually invoked at end
737 * of upper level post-processing and scsi_io_completion).
739 * Arguments: cmd - command that is complete.
740 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
741 * bytes - number of bytes of completed I/O
742 * requeue - indicates whether we should requeue leftovers.
744 * Lock status: Assumed that lock is not held upon entry.
746 * Returns: cmd if requeue required, NULL otherwise.
748 * Notes: This is called for block device requests in order to
749 * mark some number of sectors as complete.
751 * We are guaranteeing that the request queue will be goosed
752 * at some point during this call.
753 * Notes: If cmd was requeued, upon return it will be a stale pointer.
755 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int uptodate
,
756 int bytes
, int requeue
)
758 request_queue_t
*q
= cmd
->device
->request_queue
;
759 struct request
*req
= cmd
->request
;
763 * If there are blocks left over at the end, set up the command
764 * to queue the remainder of them.
766 if (end_that_request_chunk(req
, uptodate
, bytes
)) {
767 int leftover
= (req
->hard_nr_sectors
<< 9);
769 if (blk_pc_request(req
))
770 leftover
= req
->data_len
;
772 /* kill remainder if no retrys */
773 if (!uptodate
&& blk_noretry_request(req
))
774 end_that_request_chunk(req
, 0, leftover
);
778 * Bleah. Leftovers again. Stick the
779 * leftovers in the front of the
780 * queue, and goose the queue again.
782 scsi_requeue_command(q
, cmd
);
789 add_disk_randomness(req
->rq_disk
);
791 spin_lock_irqsave(q
->queue_lock
, flags
);
792 if (blk_rq_tagged(req
))
793 blk_queue_end_tag(q
, req
);
794 end_that_request_last(req
);
795 spin_unlock_irqrestore(q
->queue_lock
, flags
);
798 * This will goose the queue request function at the end, so we don't
799 * need to worry about launching another command.
801 scsi_next_command(cmd
);
805 static struct scatterlist
*scsi_alloc_sgtable(struct scsi_cmnd
*cmd
, gfp_t gfp_mask
)
807 struct scsi_host_sg_pool
*sgp
;
808 struct scatterlist
*sgl
;
810 BUG_ON(!cmd
->use_sg
);
812 switch (cmd
->use_sg
) {
822 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
826 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
830 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
841 sgp
= scsi_sg_pools
+ cmd
->sglist_len
;
842 sgl
= mempool_alloc(sgp
->pool
, gfp_mask
);
846 static void scsi_free_sgtable(struct scatterlist
*sgl
, int index
)
848 struct scsi_host_sg_pool
*sgp
;
850 BUG_ON(index
>= SG_MEMPOOL_NR
);
852 sgp
= scsi_sg_pools
+ index
;
853 mempool_free(sgl
, sgp
->pool
);
857 * Function: scsi_release_buffers()
859 * Purpose: Completion processing for block device I/O requests.
861 * Arguments: cmd - command that we are bailing.
863 * Lock status: Assumed that no lock is held upon entry.
867 * Notes: In the event that an upper level driver rejects a
868 * command, we must release resources allocated during
869 * the __init_io() function. Primarily this would involve
870 * the scatter-gather table, and potentially any bounce
873 static void scsi_release_buffers(struct scsi_cmnd
*cmd
)
875 struct request
*req
= cmd
->request
;
878 * Free up any indirection buffers we allocated for DMA purposes.
881 scsi_free_sgtable(cmd
->request_buffer
, cmd
->sglist_len
);
882 else if (cmd
->request_buffer
!= req
->buffer
)
883 kfree(cmd
->request_buffer
);
886 * Zero these out. They now point to freed memory, and it is
887 * dangerous to hang onto the pointers.
891 cmd
->request_buffer
= NULL
;
892 cmd
->request_bufflen
= 0;
896 * Function: scsi_io_completion()
898 * Purpose: Completion processing for block device I/O requests.
900 * Arguments: cmd - command that is finished.
902 * Lock status: Assumed that no lock is held upon entry.
906 * Notes: This function is matched in terms of capabilities to
907 * the function that created the scatter-gather list.
908 * In other words, if there are no bounce buffers
909 * (the normal case for most drivers), we don't need
910 * the logic to deal with cleaning up afterwards.
912 * We must do one of several things here:
914 * a) Call scsi_end_request. This will finish off the
915 * specified number of sectors. If we are done, the
916 * command block will be released, and the queue
917 * function will be goosed. If we are not done, then
918 * scsi_end_request will directly goose the queue.
920 * b) We can just use scsi_requeue_command() here. This would
921 * be used if we just wanted to retry, for example.
923 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
,
924 unsigned int block_bytes
)
926 int result
= cmd
->result
;
927 int this_count
= cmd
->bufflen
;
928 request_queue_t
*q
= cmd
->device
->request_queue
;
929 struct request
*req
= cmd
->request
;
930 int clear_errors
= 1;
931 struct scsi_sense_hdr sshdr
;
933 int sense_deferred
= 0;
935 if (blk_complete_barrier_rq(q
, req
, good_bytes
>> 9))
939 * Free up any indirection buffers we allocated for DMA purposes.
940 * For the case of a READ, we need to copy the data out of the
941 * bounce buffer and into the real buffer.
944 scsi_free_sgtable(cmd
->buffer
, cmd
->sglist_len
);
945 else if (cmd
->buffer
!= req
->buffer
) {
946 if (rq_data_dir(req
) == READ
) {
948 char *to
= bio_kmap_irq(req
->bio
, &flags
);
949 memcpy(to
, cmd
->buffer
, cmd
->bufflen
);
950 bio_kunmap_irq(to
, &flags
);
956 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
958 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
960 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
961 req
->errors
= result
;
964 if (sense_valid
&& req
->sense
) {
966 * SG_IO wants current and deferred errors
968 int len
= 8 + cmd
->sense_buffer
[7];
970 if (len
> SCSI_SENSE_BUFFERSIZE
)
971 len
= SCSI_SENSE_BUFFERSIZE
;
972 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
973 req
->sense_len
= len
;
976 req
->data_len
= cmd
->resid
;
980 * Zero these out. They now point to freed memory, and it is
981 * dangerous to hang onto the pointers.
985 cmd
->request_buffer
= NULL
;
986 cmd
->request_bufflen
= 0;
989 * Next deal with any sectors which we were able to correctly
992 if (good_bytes
>= 0) {
993 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
994 req
->nr_sectors
, good_bytes
));
995 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd
->use_sg
));
1000 * If multiple sectors are requested in one buffer, then
1001 * they will have been finished off by the first command.
1002 * If not, then we have a multi-buffer command.
1004 * If block_bytes != 0, it means we had a medium error
1005 * of some sort, and that we want to mark some number of
1006 * sectors as not uptodate. Thus we want to inhibit
1007 * requeueing right here - we will requeue down below
1008 * when we handle the bad sectors.
1012 * If the command completed without error, then either
1013 * finish off the rest of the command, or start a new one.
1015 if (scsi_end_request(cmd
, 1, good_bytes
, result
== 0) == NULL
)
1019 * Now, if we were good little boys and girls, Santa left us a request
1020 * sense buffer. We can extract information from this, so we
1021 * can choose a block to remap, etc.
1023 if (sense_valid
&& !sense_deferred
) {
1024 switch (sshdr
.sense_key
) {
1025 case UNIT_ATTENTION
:
1026 if (cmd
->device
->removable
) {
1027 /* detected disc change. set a bit
1028 * and quietly refuse further access.
1030 cmd
->device
->changed
= 1;
1031 scsi_end_request(cmd
, 0,
1036 * Must have been a power glitch, or a
1037 * bus reset. Could not have been a
1038 * media change, so we just retry the
1039 * request and see what happens.
1041 scsi_requeue_command(q
, cmd
);
1045 case ILLEGAL_REQUEST
:
1047 * If we had an ILLEGAL REQUEST returned, then we may
1048 * have performed an unsupported command. The only
1049 * thing this should be would be a ten byte read where
1050 * only a six byte read was supported. Also, on a
1051 * system where READ CAPACITY failed, we may have read
1052 * past the end of the disk.
1054 if ((cmd
->device
->use_10_for_rw
&&
1055 sshdr
.asc
== 0x20 && sshdr
.ascq
== 0x00) &&
1056 (cmd
->cmnd
[0] == READ_10
||
1057 cmd
->cmnd
[0] == WRITE_10
)) {
1058 cmd
->device
->use_10_for_rw
= 0;
1060 * This will cause a retry with a 6-byte
1063 scsi_requeue_command(q
, cmd
);
1066 scsi_end_request(cmd
, 0, this_count
, 1);
1072 * If the device is in the process of becoming ready,
1075 if (sshdr
.asc
== 0x04 && sshdr
.ascq
== 0x01) {
1076 scsi_requeue_command(q
, cmd
);
1079 if (!(req
->flags
& REQ_QUIET
))
1080 scmd_printk(KERN_INFO
, cmd
,
1081 "Device not ready.\n");
1082 scsi_end_request(cmd
, 0, this_count
, 1);
1084 case VOLUME_OVERFLOW
:
1085 if (!(req
->flags
& REQ_QUIET
)) {
1086 scmd_printk(KERN_INFO
, cmd
,
1087 "Volume overflow, CDB: ");
1088 __scsi_print_command(cmd
->data_cmnd
);
1089 scsi_print_sense("", cmd
);
1091 scsi_end_request(cmd
, 0, block_bytes
, 1);
1096 } /* driver byte != 0 */
1097 if (host_byte(result
) == DID_RESET
) {
1099 * Third party bus reset or reset for error
1100 * recovery reasons. Just retry the request
1101 * and see what happens.
1103 scsi_requeue_command(q
, cmd
);
1107 if (!(req
->flags
& REQ_QUIET
)) {
1108 scmd_printk(KERN_INFO
, cmd
,
1109 "SCSI error: return code = 0x%x\n", result
);
1111 if (driver_byte(result
) & DRIVER_SENSE
)
1112 scsi_print_sense("", cmd
);
1115 * Mark a single buffer as not uptodate. Queue the remainder.
1116 * We sometimes get this cruft in the event that a medium error
1117 * isn't properly reported.
1119 block_bytes
= req
->hard_cur_sectors
<< 9;
1121 block_bytes
= req
->data_len
;
1122 scsi_end_request(cmd
, 0, block_bytes
, 1);
1125 EXPORT_SYMBOL(scsi_io_completion
);
1128 * Function: scsi_init_io()
1130 * Purpose: SCSI I/O initialize function.
1132 * Arguments: cmd - Command descriptor we wish to initialize
1134 * Returns: 0 on success
1135 * BLKPREP_DEFER if the failure is retryable
1136 * BLKPREP_KILL if the failure is fatal
1138 static int scsi_init_io(struct scsi_cmnd
*cmd
)
1140 struct request
*req
= cmd
->request
;
1141 struct scatterlist
*sgpnt
;
1145 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
1147 if ((req
->flags
& REQ_BLOCK_PC
) && !req
->bio
) {
1148 cmd
->request_bufflen
= req
->data_len
;
1149 cmd
->request_buffer
= req
->data
;
1150 req
->buffer
= req
->data
;
1156 * we used to not use scatter-gather for single segment request,
1157 * but now we do (it makes highmem I/O easier to support without
1160 cmd
->use_sg
= req
->nr_phys_segments
;
1163 * if sg table allocation fails, requeue request later.
1165 sgpnt
= scsi_alloc_sgtable(cmd
, GFP_ATOMIC
);
1166 if (unlikely(!sgpnt
)) {
1167 scsi_unprep_request(req
);
1168 return BLKPREP_DEFER
;
1171 cmd
->request_buffer
= (char *) sgpnt
;
1172 cmd
->request_bufflen
= req
->nr_sectors
<< 9;
1173 if (blk_pc_request(req
))
1174 cmd
->request_bufflen
= req
->data_len
;
1178 * Next, walk the list, and fill in the addresses and sizes of
1181 count
= blk_rq_map_sg(req
->q
, req
, cmd
->request_buffer
);
1184 * mapped well, send it off
1186 if (likely(count
<= cmd
->use_sg
)) {
1187 cmd
->use_sg
= count
;
1191 printk(KERN_ERR
"Incorrect number of segments after building list\n");
1192 printk(KERN_ERR
"counted %d, received %d\n", count
, cmd
->use_sg
);
1193 printk(KERN_ERR
"req nr_sec %lu, cur_nr_sec %u\n", req
->nr_sectors
,
1194 req
->current_nr_sectors
);
1196 /* release the command and kill it */
1197 scsi_release_buffers(cmd
);
1198 scsi_put_command(cmd
);
1199 return BLKPREP_KILL
;
1202 static int scsi_prepare_flush_fn(request_queue_t
*q
, struct request
*rq
)
1204 struct scsi_device
*sdev
= q
->queuedata
;
1205 struct scsi_driver
*drv
;
1207 if (sdev
->sdev_state
== SDEV_RUNNING
) {
1208 drv
= *(struct scsi_driver
**) rq
->rq_disk
->private_data
;
1210 if (drv
->prepare_flush
)
1211 return drv
->prepare_flush(q
, rq
);
1217 static void scsi_end_flush_fn(request_queue_t
*q
, struct request
*rq
)
1219 struct scsi_device
*sdev
= q
->queuedata
;
1220 struct request
*flush_rq
= rq
->end_io_data
;
1221 struct scsi_driver
*drv
;
1223 if (flush_rq
->errors
) {
1224 printk("scsi: barrier error, disabling flush support\n");
1225 blk_queue_ordered(q
, QUEUE_ORDERED_NONE
);
1228 if (sdev
->sdev_state
== SDEV_RUNNING
) {
1229 drv
= *(struct scsi_driver
**) rq
->rq_disk
->private_data
;
1230 drv
->end_flush(q
, rq
);
1234 static int scsi_issue_flush_fn(request_queue_t
*q
, struct gendisk
*disk
,
1235 sector_t
*error_sector
)
1237 struct scsi_device
*sdev
= q
->queuedata
;
1238 struct scsi_driver
*drv
;
1240 if (sdev
->sdev_state
!= SDEV_RUNNING
)
1243 drv
= *(struct scsi_driver
**) disk
->private_data
;
1244 if (drv
->issue_flush
)
1245 return drv
->issue_flush(&sdev
->sdev_gendev
, error_sector
);
1250 static void scsi_generic_done(struct scsi_cmnd
*cmd
)
1252 BUG_ON(!blk_pc_request(cmd
->request
));
1254 * This will complete the whole command with uptodate=1 so
1255 * as far as the block layer is concerned the command completed
1256 * successfully. Since this is a REQ_BLOCK_PC command the
1257 * caller should check the request's errors value
1259 scsi_io_completion(cmd
, cmd
->bufflen
, 0);
1262 void scsi_setup_blk_pc_cmnd(struct scsi_cmnd
*cmd
)
1264 struct request
*req
= cmd
->request
;
1266 BUG_ON(sizeof(req
->cmd
) > sizeof(cmd
->cmnd
));
1267 memcpy(cmd
->cmnd
, req
->cmd
, sizeof(cmd
->cmnd
));
1268 cmd
->cmd_len
= req
->cmd_len
;
1270 cmd
->sc_data_direction
= DMA_NONE
;
1271 else if (rq_data_dir(req
) == WRITE
)
1272 cmd
->sc_data_direction
= DMA_TO_DEVICE
;
1274 cmd
->sc_data_direction
= DMA_FROM_DEVICE
;
1276 cmd
->transfersize
= req
->data_len
;
1277 cmd
->allowed
= req
->retries
;
1278 cmd
->timeout_per_command
= req
->timeout
;
1280 EXPORT_SYMBOL_GPL(scsi_setup_blk_pc_cmnd
);
1282 static int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1284 struct scsi_device
*sdev
= q
->queuedata
;
1285 struct scsi_cmnd
*cmd
;
1286 int specials_only
= 0;
1289 * Just check to see if the device is online. If it isn't, we
1290 * refuse to process any commands. The device must be brought
1291 * online before trying any recovery commands
1293 if (unlikely(!scsi_device_online(sdev
))) {
1294 sdev_printk(KERN_ERR
, sdev
,
1295 "rejecting I/O to offline device\n");
1298 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1299 /* OK, we're not in a running state don't prep
1301 if (sdev
->sdev_state
== SDEV_DEL
) {
1302 /* Device is fully deleted, no commands
1303 * at all allowed down */
1304 sdev_printk(KERN_ERR
, sdev
,
1305 "rejecting I/O to dead device\n");
1308 /* OK, we only allow special commands (i.e. not
1309 * user initiated ones */
1310 specials_only
= sdev
->sdev_state
;
1314 * Find the actual device driver associated with this command.
1315 * The SPECIAL requests are things like character device or
1316 * ioctls, which did not originate from ll_rw_blk. Note that
1317 * the special field is also used to indicate the cmd for
1318 * the remainder of a partially fulfilled request that can
1319 * come up when there is a medium error. We have to treat
1320 * these two cases differently. We differentiate by looking
1321 * at request->cmd, as this tells us the real story.
1323 if (req
->flags
& REQ_SPECIAL
&& req
->special
) {
1324 struct scsi_request
*sreq
= req
->special
;
1326 if (sreq
->sr_magic
== SCSI_REQ_MAGIC
) {
1327 cmd
= scsi_get_command(sreq
->sr_device
, GFP_ATOMIC
);
1330 scsi_init_cmd_from_req(cmd
, sreq
);
1333 } else if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1335 if(unlikely(specials_only
) && !(req
->flags
& REQ_SPECIAL
)) {
1336 if(specials_only
== SDEV_QUIESCE
||
1337 specials_only
== SDEV_BLOCK
)
1340 sdev_printk(KERN_ERR
, sdev
,
1341 "rejecting I/O to device being removed\n");
1347 * Now try and find a command block that we can use.
1349 if (!req
->special
) {
1350 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1356 /* pull a tag out of the request if we have one */
1357 cmd
->tag
= req
->tag
;
1359 blk_dump_rq_flags(req
, "SCSI bad req");
1363 /* note the overloading of req->special. When the tag
1364 * is active it always means cmd. If the tag goes
1365 * back for re-queueing, it may be reset */
1370 * FIXME: drop the lock here because the functions below
1371 * expect to be called without the queue lock held. Also,
1372 * previously, we dequeued the request before dropping the
1373 * lock. We hope REQ_STARTED prevents anything untoward from
1376 if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1377 struct scsi_driver
*drv
;
1381 * This will do a couple of things:
1382 * 1) Fill in the actual SCSI command.
1383 * 2) Fill in any other upper-level specific fields
1386 * If this returns 0, it means that the request failed
1387 * (reading past end of disk, reading offline device,
1388 * etc). This won't actually talk to the device, but
1389 * some kinds of consistency checking may cause the
1390 * request to be rejected immediately.
1394 * This sets up the scatter-gather table (allocating if
1397 ret
= scsi_init_io(cmd
);
1399 /* For BLKPREP_KILL/DEFER the cmd was released */
1407 * Initialize the actual SCSI command for this request.
1410 drv
= *(struct scsi_driver
**)req
->rq_disk
->private_data
;
1411 if (unlikely(!drv
->init_command(cmd
))) {
1412 scsi_release_buffers(cmd
);
1413 scsi_put_command(cmd
);
1417 scsi_setup_blk_pc_cmnd(cmd
);
1418 cmd
->done
= scsi_generic_done
;
1423 * The request is now prepped, no need to come back here
1425 req
->flags
|= REQ_DONTPREP
;
1429 /* If we defer, the elv_next_request() returns NULL, but the
1430 * queue must be restarted, so we plug here if no returning
1431 * command will automatically do that. */
1432 if (sdev
->device_busy
== 0)
1434 return BLKPREP_DEFER
;
1436 req
->errors
= DID_NO_CONNECT
<< 16;
1437 return BLKPREP_KILL
;
1441 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1444 * Called with the queue_lock held.
1446 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1447 struct scsi_device
*sdev
)
1449 if (sdev
->device_busy
>= sdev
->queue_depth
)
1451 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1453 * unblock after device_blocked iterates to zero
1455 if (--sdev
->device_blocked
== 0) {
1457 sdev_printk(KERN_INFO
, sdev
,
1458 "unblocking device at zero depth\n"));
1464 if (sdev
->device_blocked
)
1471 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1472 * return 0. We must end up running the queue again whenever 0 is
1473 * returned, else IO can hang.
1475 * Called with host_lock held.
1477 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1478 struct Scsi_Host
*shost
,
1479 struct scsi_device
*sdev
)
1481 if (scsi_host_in_recovery(shost
))
1483 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1485 * unblock after host_blocked iterates to zero
1487 if (--shost
->host_blocked
== 0) {
1489 printk("scsi%d unblocking host at zero depth\n",
1496 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
1497 shost
->host_blocked
|| shost
->host_self_blocked
) {
1498 if (list_empty(&sdev
->starved_entry
))
1499 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1503 /* We're OK to process the command, so we can't be starved */
1504 if (!list_empty(&sdev
->starved_entry
))
1505 list_del_init(&sdev
->starved_entry
);
1511 * Kill a request for a dead device
1513 static void scsi_kill_request(struct request
*req
, request_queue_t
*q
)
1515 struct scsi_cmnd
*cmd
= req
->special
;
1517 blkdev_dequeue_request(req
);
1519 if (unlikely(cmd
== NULL
)) {
1520 printk(KERN_CRIT
"impossible request in %s.\n",
1525 scsi_init_cmd_errh(cmd
);
1526 cmd
->result
= DID_NO_CONNECT
<< 16;
1527 atomic_inc(&cmd
->device
->iorequest_cnt
);
1532 * Function: scsi_request_fn()
1534 * Purpose: Main strategy routine for SCSI.
1536 * Arguments: q - Pointer to actual queue.
1540 * Lock status: IO request lock assumed to be held when called.
1542 static void scsi_request_fn(struct request_queue
*q
)
1544 struct scsi_device
*sdev
= q
->queuedata
;
1545 struct Scsi_Host
*shost
;
1546 struct scsi_cmnd
*cmd
;
1547 struct request
*req
;
1550 printk("scsi: killing requests for dead queue\n");
1551 while ((req
= elv_next_request(q
)) != NULL
)
1552 scsi_kill_request(req
, q
);
1556 if(!get_device(&sdev
->sdev_gendev
))
1557 /* We must be tearing the block queue down already */
1561 * To start with, we keep looping until the queue is empty, or until
1562 * the host is no longer able to accept any more requests.
1565 while (!blk_queue_plugged(q
)) {
1568 * get next queueable request. We do this early to make sure
1569 * that the request is fully prepared even if we cannot
1572 req
= elv_next_request(q
);
1573 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1576 if (unlikely(!scsi_device_online(sdev
))) {
1577 sdev_printk(KERN_ERR
, sdev
,
1578 "rejecting I/O to offline device\n");
1579 scsi_kill_request(req
, q
);
1585 * Remove the request from the request list.
1587 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1588 blkdev_dequeue_request(req
);
1589 sdev
->device_busy
++;
1591 spin_unlock(q
->queue_lock
);
1593 if (unlikely(cmd
== NULL
)) {
1594 printk(KERN_CRIT
"impossible request in %s.\n"
1595 "please mail a stack trace to "
1596 "linux-scsi@vger.kernel.org",
1600 spin_lock(shost
->host_lock
);
1602 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1604 if (sdev
->single_lun
) {
1605 if (scsi_target(sdev
)->starget_sdev_user
&&
1606 scsi_target(sdev
)->starget_sdev_user
!= sdev
)
1608 scsi_target(sdev
)->starget_sdev_user
= sdev
;
1613 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1614 * take the lock again.
1616 spin_unlock_irq(shost
->host_lock
);
1619 * Finally, initialize any error handling parameters, and set up
1620 * the timers for timeouts.
1622 scsi_init_cmd_errh(cmd
);
1625 * Dispatch the command to the low-level driver.
1627 rtn
= scsi_dispatch_cmd(cmd
);
1628 spin_lock_irq(q
->queue_lock
);
1630 /* we're refusing the command; because of
1631 * the way locks get dropped, we need to
1632 * check here if plugging is required */
1633 if(sdev
->device_busy
== 0)
1643 spin_unlock_irq(shost
->host_lock
);
1646 * lock q, handle tag, requeue req, and decrement device_busy. We
1647 * must return with queue_lock held.
1649 * Decrementing device_busy without checking it is OK, as all such
1650 * cases (host limits or settings) should run the queue at some
1653 spin_lock_irq(q
->queue_lock
);
1654 blk_requeue_request(q
, req
);
1655 sdev
->device_busy
--;
1656 if(sdev
->device_busy
== 0)
1659 /* must be careful here...if we trigger the ->remove() function
1660 * we cannot be holding the q lock */
1661 spin_unlock_irq(q
->queue_lock
);
1662 put_device(&sdev
->sdev_gendev
);
1663 spin_lock_irq(q
->queue_lock
);
1666 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1668 struct device
*host_dev
;
1669 u64 bounce_limit
= 0xffffffff;
1671 if (shost
->unchecked_isa_dma
)
1672 return BLK_BOUNCE_ISA
;
1674 * Platforms with virtual-DMA translation
1675 * hardware have no practical limit.
1677 if (!PCI_DMA_BUS_IS_PHYS
)
1678 return BLK_BOUNCE_ANY
;
1680 host_dev
= scsi_get_device(shost
);
1681 if (host_dev
&& host_dev
->dma_mask
)
1682 bounce_limit
= *host_dev
->dma_mask
;
1684 return bounce_limit
;
1686 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1688 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1690 struct Scsi_Host
*shost
= sdev
->host
;
1691 struct request_queue
*q
;
1693 q
= blk_init_queue(scsi_request_fn
, NULL
);
1697 blk_queue_prep_rq(q
, scsi_prep_fn
);
1699 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1700 blk_queue_max_phys_segments(q
, SCSI_MAX_PHYS_SEGMENTS
);
1701 blk_queue_max_sectors(q
, shost
->max_sectors
);
1702 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1703 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1704 blk_queue_issue_flush_fn(q
, scsi_issue_flush_fn
);
1707 * ordered tags are superior to flush ordering
1709 if (shost
->ordered_tag
)
1710 blk_queue_ordered(q
, QUEUE_ORDERED_TAG
);
1711 else if (shost
->ordered_flush
) {
1712 blk_queue_ordered(q
, QUEUE_ORDERED_FLUSH
);
1713 q
->prepare_flush_fn
= scsi_prepare_flush_fn
;
1714 q
->end_flush_fn
= scsi_end_flush_fn
;
1717 if (!shost
->use_clustering
)
1718 clear_bit(QUEUE_FLAG_CLUSTER
, &q
->queue_flags
);
1722 void scsi_free_queue(struct request_queue
*q
)
1724 blk_cleanup_queue(q
);
1728 * Function: scsi_block_requests()
1730 * Purpose: Utility function used by low-level drivers to prevent further
1731 * commands from being queued to the device.
1733 * Arguments: shost - Host in question
1737 * Lock status: No locks are assumed held.
1739 * Notes: There is no timer nor any other means by which the requests
1740 * get unblocked other than the low-level driver calling
1741 * scsi_unblock_requests().
1743 void scsi_block_requests(struct Scsi_Host
*shost
)
1745 shost
->host_self_blocked
= 1;
1747 EXPORT_SYMBOL(scsi_block_requests
);
1750 * Function: scsi_unblock_requests()
1752 * Purpose: Utility function used by low-level drivers to allow further
1753 * commands from being queued to the device.
1755 * Arguments: shost - Host in question
1759 * Lock status: No locks are assumed held.
1761 * Notes: There is no timer nor any other means by which the requests
1762 * get unblocked other than the low-level driver calling
1763 * scsi_unblock_requests().
1765 * This is done as an API function so that changes to the
1766 * internals of the scsi mid-layer won't require wholesale
1767 * changes to drivers that use this feature.
1769 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1771 shost
->host_self_blocked
= 0;
1772 scsi_run_host_queues(shost
);
1774 EXPORT_SYMBOL(scsi_unblock_requests
);
1776 int __init
scsi_init_queue(void)
1780 scsi_io_context_cache
= kmem_cache_create("scsi_io_context",
1781 sizeof(struct scsi_io_context
),
1783 if (!scsi_io_context_cache
) {
1784 printk(KERN_ERR
"SCSI: can't init scsi io context cache\n");
1788 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1789 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1790 int size
= sgp
->size
* sizeof(struct scatterlist
);
1792 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1793 SLAB_HWCACHE_ALIGN
, NULL
, NULL
);
1795 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1799 sgp
->pool
= mempool_create(SG_MEMPOOL_SIZE
,
1800 mempool_alloc_slab
, mempool_free_slab
,
1803 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1811 void scsi_exit_queue(void)
1815 kmem_cache_destroy(scsi_io_context_cache
);
1817 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1818 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1819 mempool_destroy(sgp
->pool
);
1820 kmem_cache_destroy(sgp
->slab
);
1824 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1825 * six bytes if necessary.
1826 * @sdev: SCSI device to be queried
1827 * @dbd: set if mode sense will allow block descriptors to be returned
1828 * @modepage: mode page being requested
1829 * @buffer: request buffer (may not be smaller than eight bytes)
1830 * @len: length of request buffer.
1831 * @timeout: command timeout
1832 * @retries: number of retries before failing
1833 * @data: returns a structure abstracting the mode header data
1834 * @sense: place to put sense data (or NULL if no sense to be collected).
1835 * must be SCSI_SENSE_BUFFERSIZE big.
1837 * Returns zero if unsuccessful, or the header offset (either 4
1838 * or 8 depending on whether a six or ten byte command was
1839 * issued) if successful.
1842 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
1843 unsigned char *buffer
, int len
, int timeout
, int retries
,
1844 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
) {
1845 unsigned char cmd
[12];
1849 struct scsi_sense_hdr my_sshdr
;
1851 memset(data
, 0, sizeof(*data
));
1852 memset(&cmd
[0], 0, 12);
1853 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
1856 /* caller might not be interested in sense, but we need it */
1861 use_10_for_ms
= sdev
->use_10_for_ms
;
1863 if (use_10_for_ms
) {
1867 cmd
[0] = MODE_SENSE_10
;
1874 cmd
[0] = MODE_SENSE
;
1879 memset(buffer
, 0, len
);
1881 result
= scsi_execute_req(sdev
, cmd
, DMA_FROM_DEVICE
, buffer
, len
,
1882 sshdr
, timeout
, retries
);
1884 /* This code looks awful: what it's doing is making sure an
1885 * ILLEGAL REQUEST sense return identifies the actual command
1886 * byte as the problem. MODE_SENSE commands can return
1887 * ILLEGAL REQUEST if the code page isn't supported */
1889 if (use_10_for_ms
&& !scsi_status_is_good(result
) &&
1890 (driver_byte(result
) & DRIVER_SENSE
)) {
1891 if (scsi_sense_valid(sshdr
)) {
1892 if ((sshdr
->sense_key
== ILLEGAL_REQUEST
) &&
1893 (sshdr
->asc
== 0x20) && (sshdr
->ascq
== 0)) {
1895 * Invalid command operation code
1897 sdev
->use_10_for_ms
= 0;
1903 if(scsi_status_is_good(result
)) {
1904 data
->header_length
= header_length
;
1906 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
1907 data
->medium_type
= buffer
[2];
1908 data
->device_specific
= buffer
[3];
1909 data
->longlba
= buffer
[4] & 0x01;
1910 data
->block_descriptor_length
= buffer
[6]*256
1913 data
->length
= buffer
[0] + 1;
1914 data
->medium_type
= buffer
[1];
1915 data
->device_specific
= buffer
[2];
1916 data
->block_descriptor_length
= buffer
[3];
1922 EXPORT_SYMBOL(scsi_mode_sense
);
1925 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
)
1928 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
1930 struct scsi_sense_hdr sshdr
;
1933 result
= scsi_execute_req(sdev
, cmd
, DMA_NONE
, NULL
, 0, &sshdr
,
1936 if ((driver_byte(result
) & DRIVER_SENSE
) && sdev
->removable
) {
1938 if ((scsi_sense_valid(&sshdr
)) &&
1939 ((sshdr
.sense_key
== UNIT_ATTENTION
) ||
1940 (sshdr
.sense_key
== NOT_READY
))) {
1947 EXPORT_SYMBOL(scsi_test_unit_ready
);
1950 * scsi_device_set_state - Take the given device through the device
1952 * @sdev: scsi device to change the state of.
1953 * @state: state to change to.
1955 * Returns zero if unsuccessful or an error if the requested
1956 * transition is illegal.
1959 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
1961 enum scsi_device_state oldstate
= sdev
->sdev_state
;
1963 if (state
== oldstate
)
1968 /* There are no legal states that come back to
1969 * created. This is the manually initialised start
2039 sdev
->sdev_state
= state
;
2043 SCSI_LOG_ERROR_RECOVERY(1,
2044 sdev_printk(KERN_ERR
, sdev
,
2045 "Illegal state transition %s->%s\n",
2046 scsi_device_state_name(oldstate
),
2047 scsi_device_state_name(state
))
2051 EXPORT_SYMBOL(scsi_device_set_state
);
2054 * scsi_device_quiesce - Block user issued commands.
2055 * @sdev: scsi device to quiesce.
2057 * This works by trying to transition to the SDEV_QUIESCE state
2058 * (which must be a legal transition). When the device is in this
2059 * state, only special requests will be accepted, all others will
2060 * be deferred. Since special requests may also be requeued requests,
2061 * a successful return doesn't guarantee the device will be
2062 * totally quiescent.
2064 * Must be called with user context, may sleep.
2066 * Returns zero if unsuccessful or an error if not.
2069 scsi_device_quiesce(struct scsi_device
*sdev
)
2071 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
2075 scsi_run_queue(sdev
->request_queue
);
2076 while (sdev
->device_busy
) {
2077 msleep_interruptible(200);
2078 scsi_run_queue(sdev
->request_queue
);
2082 EXPORT_SYMBOL(scsi_device_quiesce
);
2085 * scsi_device_resume - Restart user issued commands to a quiesced device.
2086 * @sdev: scsi device to resume.
2088 * Moves the device from quiesced back to running and restarts the
2091 * Must be called with user context, may sleep.
2094 scsi_device_resume(struct scsi_device
*sdev
)
2096 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
2098 scsi_run_queue(sdev
->request_queue
);
2100 EXPORT_SYMBOL(scsi_device_resume
);
2103 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
2105 scsi_device_quiesce(sdev
);
2109 scsi_target_quiesce(struct scsi_target
*starget
)
2111 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
2113 EXPORT_SYMBOL(scsi_target_quiesce
);
2116 device_resume_fn(struct scsi_device
*sdev
, void *data
)
2118 scsi_device_resume(sdev
);
2122 scsi_target_resume(struct scsi_target
*starget
)
2124 starget_for_each_device(starget
, NULL
, device_resume_fn
);
2126 EXPORT_SYMBOL(scsi_target_resume
);
2129 * scsi_internal_device_block - internal function to put a device
2130 * temporarily into the SDEV_BLOCK state
2131 * @sdev: device to block
2133 * Block request made by scsi lld's to temporarily stop all
2134 * scsi commands on the specified device. Called from interrupt
2135 * or normal process context.
2137 * Returns zero if successful or error if not
2140 * This routine transitions the device to the SDEV_BLOCK state
2141 * (which must be a legal transition). When the device is in this
2142 * state, all commands are deferred until the scsi lld reenables
2143 * the device with scsi_device_unblock or device_block_tmo fires.
2144 * This routine assumes the host_lock is held on entry.
2147 scsi_internal_device_block(struct scsi_device
*sdev
)
2149 request_queue_t
*q
= sdev
->request_queue
;
2150 unsigned long flags
;
2153 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
2158 * The device has transitioned to SDEV_BLOCK. Stop the
2159 * block layer from calling the midlayer with this device's
2162 spin_lock_irqsave(q
->queue_lock
, flags
);
2164 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2168 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
2171 * scsi_internal_device_unblock - resume a device after a block request
2172 * @sdev: device to resume
2174 * Called by scsi lld's or the midlayer to restart the device queue
2175 * for the previously suspended scsi device. Called from interrupt or
2176 * normal process context.
2178 * Returns zero if successful or error if not.
2181 * This routine transitions the device to the SDEV_RUNNING state
2182 * (which must be a legal transition) allowing the midlayer to
2183 * goose the queue for this device. This routine assumes the
2184 * host_lock is held upon entry.
2187 scsi_internal_device_unblock(struct scsi_device
*sdev
)
2189 request_queue_t
*q
= sdev
->request_queue
;
2191 unsigned long flags
;
2194 * Try to transition the scsi device to SDEV_RUNNING
2195 * and goose the device queue if successful.
2197 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
2201 spin_lock_irqsave(q
->queue_lock
, flags
);
2203 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2207 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
2210 device_block(struct scsi_device
*sdev
, void *data
)
2212 scsi_internal_device_block(sdev
);
2216 target_block(struct device
*dev
, void *data
)
2218 if (scsi_is_target_device(dev
))
2219 starget_for_each_device(to_scsi_target(dev
), NULL
,
2225 scsi_target_block(struct device
*dev
)
2227 if (scsi_is_target_device(dev
))
2228 starget_for_each_device(to_scsi_target(dev
), NULL
,
2231 device_for_each_child(dev
, NULL
, target_block
);
2233 EXPORT_SYMBOL_GPL(scsi_target_block
);
2236 device_unblock(struct scsi_device
*sdev
, void *data
)
2238 scsi_internal_device_unblock(sdev
);
2242 target_unblock(struct device
*dev
, void *data
)
2244 if (scsi_is_target_device(dev
))
2245 starget_for_each_device(to_scsi_target(dev
), NULL
,
2251 scsi_target_unblock(struct device
*dev
)
2253 if (scsi_is_target_device(dev
))
2254 starget_for_each_device(to_scsi_target(dev
), NULL
,
2257 device_for_each_child(dev
, NULL
, target_unblock
);
2259 EXPORT_SYMBOL_GPL(scsi_target_unblock
);