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
, int uptodate
)
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 * @cmd_len: length of scsi cdb
440 * @data_direction: data direction
441 * @buffer: data buffer (this can be a kernel buffer or scatterlist)
442 * @bufflen: len of buffer
443 * @use_sg: if buffer is a scatterlist this is the number of elements
444 * @timeout: request timeout in seconds
445 * @retries: number of times to retry request
446 * @flags: or into request flags
448 int scsi_execute_async(struct scsi_device
*sdev
, const unsigned char *cmd
,
449 int cmd_len
, int data_direction
, void *buffer
, unsigned bufflen
,
450 int use_sg
, int timeout
, int retries
, void *privdata
,
451 void (*done
)(void *, char *, int, int), gfp_t gfp
)
454 struct scsi_io_context
*sioc
;
456 int write
= (data_direction
== DMA_TO_DEVICE
);
458 sioc
= kmem_cache_alloc(scsi_io_context_cache
, gfp
);
460 return DRIVER_ERROR
<< 24;
461 memset(sioc
, 0, sizeof(*sioc
));
463 req
= blk_get_request(sdev
->request_queue
, write
, gfp
);
466 req
->flags
|= REQ_BLOCK_PC
| REQ_QUIET
;
469 err
= scsi_req_map_sg(req
, buffer
, use_sg
, bufflen
, gfp
);
471 err
= blk_rq_map_kern(req
->q
, req
, buffer
, bufflen
, gfp
);
476 req
->cmd_len
= cmd_len
;
477 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
478 req
->sense
= sioc
->sense
;
480 req
->timeout
= timeout
;
481 req
->retries
= retries
;
482 req
->end_io_data
= sioc
;
484 sioc
->data
= privdata
;
487 blk_execute_rq_nowait(req
->q
, NULL
, req
, 1, scsi_end_async
);
491 blk_put_request(req
);
494 return DRIVER_ERROR
<< 24;
496 EXPORT_SYMBOL_GPL(scsi_execute_async
);
499 * Function: scsi_init_cmd_errh()
501 * Purpose: Initialize cmd fields related to error handling.
503 * Arguments: cmd - command that is ready to be queued.
507 * Notes: This function has the job of initializing a number of
508 * fields related to error handling. Typically this will
509 * be called once for each command, as required.
511 static int scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
513 cmd
->serial_number
= 0;
515 memset(cmd
->sense_buffer
, 0, sizeof cmd
->sense_buffer
);
517 if (cmd
->cmd_len
== 0)
518 cmd
->cmd_len
= COMMAND_SIZE(cmd
->cmnd
[0]);
521 * We need saved copies of a number of fields - this is because
522 * error handling may need to overwrite these with different values
523 * to run different commands, and once error handling is complete,
524 * we will need to restore these values prior to running the actual
527 cmd
->old_use_sg
= cmd
->use_sg
;
528 cmd
->old_cmd_len
= cmd
->cmd_len
;
529 cmd
->sc_old_data_direction
= cmd
->sc_data_direction
;
530 cmd
->old_underflow
= cmd
->underflow
;
531 memcpy(cmd
->data_cmnd
, cmd
->cmnd
, sizeof(cmd
->cmnd
));
532 cmd
->buffer
= cmd
->request_buffer
;
533 cmd
->bufflen
= cmd
->request_bufflen
;
539 * Function: scsi_setup_cmd_retry()
541 * Purpose: Restore the command state for a retry
543 * Arguments: cmd - command to be restored
547 * Notes: Immediately prior to retrying a command, we need
548 * to restore certain fields that we saved above.
550 void scsi_setup_cmd_retry(struct scsi_cmnd
*cmd
)
552 memcpy(cmd
->cmnd
, cmd
->data_cmnd
, sizeof(cmd
->data_cmnd
));
553 cmd
->request_buffer
= cmd
->buffer
;
554 cmd
->request_bufflen
= cmd
->bufflen
;
555 cmd
->use_sg
= cmd
->old_use_sg
;
556 cmd
->cmd_len
= cmd
->old_cmd_len
;
557 cmd
->sc_data_direction
= cmd
->sc_old_data_direction
;
558 cmd
->underflow
= cmd
->old_underflow
;
561 void scsi_device_unbusy(struct scsi_device
*sdev
)
563 struct Scsi_Host
*shost
= sdev
->host
;
566 spin_lock_irqsave(shost
->host_lock
, flags
);
568 if (unlikely(scsi_host_in_recovery(shost
) &&
570 scsi_eh_wakeup(shost
);
571 spin_unlock(shost
->host_lock
);
572 spin_lock(sdev
->request_queue
->queue_lock
);
574 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
578 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
579 * and call blk_run_queue for all the scsi_devices on the target -
580 * including current_sdev first.
582 * Called with *no* scsi locks held.
584 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
586 struct Scsi_Host
*shost
= current_sdev
->host
;
587 struct scsi_device
*sdev
, *tmp
;
588 struct scsi_target
*starget
= scsi_target(current_sdev
);
591 spin_lock_irqsave(shost
->host_lock
, flags
);
592 starget
->starget_sdev_user
= NULL
;
593 spin_unlock_irqrestore(shost
->host_lock
, flags
);
596 * Call blk_run_queue for all LUNs on the target, starting with
597 * current_sdev. We race with others (to set starget_sdev_user),
598 * but in most cases, we will be first. Ideally, each LU on the
599 * target would get some limited time or requests on the target.
601 blk_run_queue(current_sdev
->request_queue
);
603 spin_lock_irqsave(shost
->host_lock
, flags
);
604 if (starget
->starget_sdev_user
)
606 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
607 same_target_siblings
) {
608 if (sdev
== current_sdev
)
610 if (scsi_device_get(sdev
))
613 spin_unlock_irqrestore(shost
->host_lock
, flags
);
614 blk_run_queue(sdev
->request_queue
);
615 spin_lock_irqsave(shost
->host_lock
, flags
);
617 scsi_device_put(sdev
);
620 spin_unlock_irqrestore(shost
->host_lock
, flags
);
624 * Function: scsi_run_queue()
626 * Purpose: Select a proper request queue to serve next
628 * Arguments: q - last request's queue
632 * Notes: The previous command was completely finished, start
633 * a new one if possible.
635 static void scsi_run_queue(struct request_queue
*q
)
637 struct scsi_device
*sdev
= q
->queuedata
;
638 struct Scsi_Host
*shost
= sdev
->host
;
641 if (sdev
->single_lun
)
642 scsi_single_lun_run(sdev
);
644 spin_lock_irqsave(shost
->host_lock
, flags
);
645 while (!list_empty(&shost
->starved_list
) &&
646 !shost
->host_blocked
&& !shost
->host_self_blocked
&&
647 !((shost
->can_queue
> 0) &&
648 (shost
->host_busy
>= shost
->can_queue
))) {
650 * As long as shost is accepting commands and we have
651 * starved queues, call blk_run_queue. scsi_request_fn
652 * drops the queue_lock and can add us back to the
655 * host_lock protects the starved_list and starved_entry.
656 * scsi_request_fn must get the host_lock before checking
657 * or modifying starved_list or starved_entry.
659 sdev
= list_entry(shost
->starved_list
.next
,
660 struct scsi_device
, starved_entry
);
661 list_del_init(&sdev
->starved_entry
);
662 spin_unlock_irqrestore(shost
->host_lock
, flags
);
664 blk_run_queue(sdev
->request_queue
);
666 spin_lock_irqsave(shost
->host_lock
, flags
);
667 if (unlikely(!list_empty(&sdev
->starved_entry
)))
669 * sdev lost a race, and was put back on the
670 * starved list. This is unlikely but without this
671 * in theory we could loop forever.
675 spin_unlock_irqrestore(shost
->host_lock
, flags
);
681 * Function: scsi_requeue_command()
683 * Purpose: Handle post-processing of completed commands.
685 * Arguments: q - queue to operate on
686 * cmd - command that may need to be requeued.
690 * Notes: After command completion, there may be blocks left
691 * over which weren't finished by the previous command
692 * this can be for a number of reasons - the main one is
693 * I/O errors in the middle of the request, in which case
694 * we need to request the blocks that come after the bad
696 * Notes: Upon return, cmd is a stale pointer.
698 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
700 struct request
*req
= cmd
->request
;
703 scsi_unprep_request(req
);
704 spin_lock_irqsave(q
->queue_lock
, flags
);
705 blk_requeue_request(q
, req
);
706 spin_unlock_irqrestore(q
->queue_lock
, flags
);
711 void scsi_next_command(struct scsi_cmnd
*cmd
)
713 struct scsi_device
*sdev
= cmd
->device
;
714 struct request_queue
*q
= sdev
->request_queue
;
716 /* need to hold a reference on the device before we let go of the cmd */
717 get_device(&sdev
->sdev_gendev
);
719 scsi_put_command(cmd
);
722 /* ok to remove device now */
723 put_device(&sdev
->sdev_gendev
);
726 void scsi_run_host_queues(struct Scsi_Host
*shost
)
728 struct scsi_device
*sdev
;
730 shost_for_each_device(sdev
, shost
)
731 scsi_run_queue(sdev
->request_queue
);
735 * Function: scsi_end_request()
737 * Purpose: Post-processing of completed commands (usually invoked at end
738 * of upper level post-processing and scsi_io_completion).
740 * Arguments: cmd - command that is complete.
741 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
742 * bytes - number of bytes of completed I/O
743 * requeue - indicates whether we should requeue leftovers.
745 * Lock status: Assumed that lock is not held upon entry.
747 * Returns: cmd if requeue required, NULL otherwise.
749 * Notes: This is called for block device requests in order to
750 * mark some number of sectors as complete.
752 * We are guaranteeing that the request queue will be goosed
753 * at some point during this call.
754 * Notes: If cmd was requeued, upon return it will be a stale pointer.
756 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int uptodate
,
757 int bytes
, int requeue
)
759 request_queue_t
*q
= cmd
->device
->request_queue
;
760 struct request
*req
= cmd
->request
;
764 * If there are blocks left over at the end, set up the command
765 * to queue the remainder of them.
767 if (end_that_request_chunk(req
, uptodate
, bytes
)) {
768 int leftover
= (req
->hard_nr_sectors
<< 9);
770 if (blk_pc_request(req
))
771 leftover
= req
->data_len
;
773 /* kill remainder if no retrys */
774 if (!uptodate
&& blk_noretry_request(req
))
775 end_that_request_chunk(req
, 0, leftover
);
779 * Bleah. Leftovers again. Stick the
780 * leftovers in the front of the
781 * queue, and goose the queue again.
783 scsi_requeue_command(q
, cmd
);
790 add_disk_randomness(req
->rq_disk
);
792 spin_lock_irqsave(q
->queue_lock
, flags
);
793 if (blk_rq_tagged(req
))
794 blk_queue_end_tag(q
, req
);
795 end_that_request_last(req
, uptodate
);
796 spin_unlock_irqrestore(q
->queue_lock
, flags
);
799 * This will goose the queue request function at the end, so we don't
800 * need to worry about launching another command.
802 scsi_next_command(cmd
);
806 static struct scatterlist
*scsi_alloc_sgtable(struct scsi_cmnd
*cmd
, gfp_t gfp_mask
)
808 struct scsi_host_sg_pool
*sgp
;
809 struct scatterlist
*sgl
;
811 BUG_ON(!cmd
->use_sg
);
813 switch (cmd
->use_sg
) {
823 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
827 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
831 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
842 sgp
= scsi_sg_pools
+ cmd
->sglist_len
;
843 sgl
= mempool_alloc(sgp
->pool
, gfp_mask
);
847 static void scsi_free_sgtable(struct scatterlist
*sgl
, int index
)
849 struct scsi_host_sg_pool
*sgp
;
851 BUG_ON(index
>= SG_MEMPOOL_NR
);
853 sgp
= scsi_sg_pools
+ index
;
854 mempool_free(sgl
, sgp
->pool
);
858 * Function: scsi_release_buffers()
860 * Purpose: Completion processing for block device I/O requests.
862 * Arguments: cmd - command that we are bailing.
864 * Lock status: Assumed that no lock is held upon entry.
868 * Notes: In the event that an upper level driver rejects a
869 * command, we must release resources allocated during
870 * the __init_io() function. Primarily this would involve
871 * the scatter-gather table, and potentially any bounce
874 static void scsi_release_buffers(struct scsi_cmnd
*cmd
)
876 struct request
*req
= cmd
->request
;
879 * Free up any indirection buffers we allocated for DMA purposes.
882 scsi_free_sgtable(cmd
->request_buffer
, cmd
->sglist_len
);
883 else if (cmd
->request_buffer
!= req
->buffer
)
884 kfree(cmd
->request_buffer
);
887 * Zero these out. They now point to freed memory, and it is
888 * dangerous to hang onto the pointers.
892 cmd
->request_buffer
= NULL
;
893 cmd
->request_bufflen
= 0;
897 * Function: scsi_io_completion()
899 * Purpose: Completion processing for block device I/O requests.
901 * Arguments: cmd - command that is finished.
903 * Lock status: Assumed that no lock is held upon entry.
907 * Notes: This function is matched in terms of capabilities to
908 * the function that created the scatter-gather list.
909 * In other words, if there are no bounce buffers
910 * (the normal case for most drivers), we don't need
911 * the logic to deal with cleaning up afterwards.
913 * We must do one of several things here:
915 * a) Call scsi_end_request. This will finish off the
916 * specified number of sectors. If we are done, the
917 * command block will be released, and the queue
918 * function will be goosed. If we are not done, then
919 * scsi_end_request will directly goose the queue.
921 * b) We can just use scsi_requeue_command() here. This would
922 * be used if we just wanted to retry, for example.
924 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
,
925 unsigned int block_bytes
)
927 int result
= cmd
->result
;
928 int this_count
= cmd
->bufflen
;
929 request_queue_t
*q
= cmd
->device
->request_queue
;
930 struct request
*req
= cmd
->request
;
931 int clear_errors
= 1;
932 struct scsi_sense_hdr sshdr
;
934 int sense_deferred
= 0;
937 * Free up any indirection buffers we allocated for DMA purposes.
938 * For the case of a READ, we need to copy the data out of the
939 * bounce buffer and into the real buffer.
942 scsi_free_sgtable(cmd
->buffer
, cmd
->sglist_len
);
943 else if (cmd
->buffer
!= req
->buffer
) {
944 if (rq_data_dir(req
) == READ
) {
946 char *to
= bio_kmap_irq(req
->bio
, &flags
);
947 memcpy(to
, cmd
->buffer
, cmd
->bufflen
);
948 bio_kunmap_irq(to
, &flags
);
954 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
956 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
958 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
959 req
->errors
= result
;
962 if (sense_valid
&& req
->sense
) {
964 * SG_IO wants current and deferred errors
966 int len
= 8 + cmd
->sense_buffer
[7];
968 if (len
> SCSI_SENSE_BUFFERSIZE
)
969 len
= SCSI_SENSE_BUFFERSIZE
;
970 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
971 req
->sense_len
= len
;
974 req
->data_len
= cmd
->resid
;
978 * Zero these out. They now point to freed memory, and it is
979 * dangerous to hang onto the pointers.
983 cmd
->request_buffer
= NULL
;
984 cmd
->request_bufflen
= 0;
987 * Next deal with any sectors which we were able to correctly
990 if (good_bytes
>= 0) {
991 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
992 req
->nr_sectors
, good_bytes
));
993 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd
->use_sg
));
998 * If multiple sectors are requested in one buffer, then
999 * they will have been finished off by the first command.
1000 * If not, then we have a multi-buffer command.
1002 * If block_bytes != 0, it means we had a medium error
1003 * of some sort, and that we want to mark some number of
1004 * sectors as not uptodate. Thus we want to inhibit
1005 * requeueing right here - we will requeue down below
1006 * when we handle the bad sectors.
1010 * If the command completed without error, then either
1011 * finish off the rest of the command, or start a new one.
1013 if (scsi_end_request(cmd
, 1, good_bytes
, result
== 0) == NULL
)
1017 * Now, if we were good little boys and girls, Santa left us a request
1018 * sense buffer. We can extract information from this, so we
1019 * can choose a block to remap, etc.
1021 if (sense_valid
&& !sense_deferred
) {
1022 switch (sshdr
.sense_key
) {
1023 case UNIT_ATTENTION
:
1024 if (cmd
->device
->removable
) {
1025 /* detected disc change. set a bit
1026 * and quietly refuse further access.
1028 cmd
->device
->changed
= 1;
1029 scsi_end_request(cmd
, 0,
1034 * Must have been a power glitch, or a
1035 * bus reset. Could not have been a
1036 * media change, so we just retry the
1037 * request and see what happens.
1039 scsi_requeue_command(q
, cmd
);
1043 case ILLEGAL_REQUEST
:
1045 * If we had an ILLEGAL REQUEST returned, then we may
1046 * have performed an unsupported command. The only
1047 * thing this should be would be a ten byte read where
1048 * only a six byte read was supported. Also, on a
1049 * system where READ CAPACITY failed, we may have read
1050 * past the end of the disk.
1052 if ((cmd
->device
->use_10_for_rw
&&
1053 sshdr
.asc
== 0x20 && sshdr
.ascq
== 0x00) &&
1054 (cmd
->cmnd
[0] == READ_10
||
1055 cmd
->cmnd
[0] == WRITE_10
)) {
1056 cmd
->device
->use_10_for_rw
= 0;
1058 * This will cause a retry with a 6-byte
1061 scsi_requeue_command(q
, cmd
);
1064 scsi_end_request(cmd
, 0, this_count
, 1);
1070 * If the device is in the process of becoming ready,
1073 if (sshdr
.asc
== 0x04 && sshdr
.ascq
== 0x01) {
1074 scsi_requeue_command(q
, cmd
);
1077 if (!(req
->flags
& REQ_QUIET
))
1078 scmd_printk(KERN_INFO
, cmd
,
1079 "Device not ready.\n");
1080 scsi_end_request(cmd
, 0, this_count
, 1);
1082 case VOLUME_OVERFLOW
:
1083 if (!(req
->flags
& REQ_QUIET
)) {
1084 scmd_printk(KERN_INFO
, cmd
,
1085 "Volume overflow, CDB: ");
1086 __scsi_print_command(cmd
->data_cmnd
);
1087 scsi_print_sense("", cmd
);
1089 scsi_end_request(cmd
, 0, block_bytes
, 1);
1094 } /* driver byte != 0 */
1095 if (host_byte(result
) == DID_RESET
) {
1097 * Third party bus reset or reset for error
1098 * recovery reasons. Just retry the request
1099 * and see what happens.
1101 scsi_requeue_command(q
, cmd
);
1105 if (!(req
->flags
& REQ_QUIET
)) {
1106 scmd_printk(KERN_INFO
, cmd
,
1107 "SCSI error: return code = 0x%x\n", result
);
1109 if (driver_byte(result
) & DRIVER_SENSE
)
1110 scsi_print_sense("", cmd
);
1113 * Mark a single buffer as not uptodate. Queue the remainder.
1114 * We sometimes get this cruft in the event that a medium error
1115 * isn't properly reported.
1117 block_bytes
= req
->hard_cur_sectors
<< 9;
1119 block_bytes
= req
->data_len
;
1120 scsi_end_request(cmd
, 0, block_bytes
, 1);
1123 EXPORT_SYMBOL(scsi_io_completion
);
1126 * Function: scsi_init_io()
1128 * Purpose: SCSI I/O initialize function.
1130 * Arguments: cmd - Command descriptor we wish to initialize
1132 * Returns: 0 on success
1133 * BLKPREP_DEFER if the failure is retryable
1134 * BLKPREP_KILL if the failure is fatal
1136 static int scsi_init_io(struct scsi_cmnd
*cmd
)
1138 struct request
*req
= cmd
->request
;
1139 struct scatterlist
*sgpnt
;
1143 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
1145 if ((req
->flags
& REQ_BLOCK_PC
) && !req
->bio
) {
1146 cmd
->request_bufflen
= req
->data_len
;
1147 cmd
->request_buffer
= req
->data
;
1148 req
->buffer
= req
->data
;
1154 * we used to not use scatter-gather for single segment request,
1155 * but now we do (it makes highmem I/O easier to support without
1158 cmd
->use_sg
= req
->nr_phys_segments
;
1161 * if sg table allocation fails, requeue request later.
1163 sgpnt
= scsi_alloc_sgtable(cmd
, GFP_ATOMIC
);
1164 if (unlikely(!sgpnt
)) {
1165 scsi_unprep_request(req
);
1166 return BLKPREP_DEFER
;
1169 cmd
->request_buffer
= (char *) sgpnt
;
1170 cmd
->request_bufflen
= req
->nr_sectors
<< 9;
1171 if (blk_pc_request(req
))
1172 cmd
->request_bufflen
= req
->data_len
;
1176 * Next, walk the list, and fill in the addresses and sizes of
1179 count
= blk_rq_map_sg(req
->q
, req
, cmd
->request_buffer
);
1182 * mapped well, send it off
1184 if (likely(count
<= cmd
->use_sg
)) {
1185 cmd
->use_sg
= count
;
1189 printk(KERN_ERR
"Incorrect number of segments after building list\n");
1190 printk(KERN_ERR
"counted %d, received %d\n", count
, cmd
->use_sg
);
1191 printk(KERN_ERR
"req nr_sec %lu, cur_nr_sec %u\n", req
->nr_sectors
,
1192 req
->current_nr_sectors
);
1194 /* release the command and kill it */
1195 scsi_release_buffers(cmd
);
1196 scsi_put_command(cmd
);
1197 return BLKPREP_KILL
;
1200 static int scsi_issue_flush_fn(request_queue_t
*q
, struct gendisk
*disk
,
1201 sector_t
*error_sector
)
1203 struct scsi_device
*sdev
= q
->queuedata
;
1204 struct scsi_driver
*drv
;
1206 if (sdev
->sdev_state
!= SDEV_RUNNING
)
1209 drv
= *(struct scsi_driver
**) disk
->private_data
;
1210 if (drv
->issue_flush
)
1211 return drv
->issue_flush(&sdev
->sdev_gendev
, error_sector
);
1216 static void scsi_blk_pc_done(struct scsi_cmnd
*cmd
)
1218 BUG_ON(!blk_pc_request(cmd
->request
));
1220 * This will complete the whole command with uptodate=1 so
1221 * as far as the block layer is concerned the command completed
1222 * successfully. Since this is a REQ_BLOCK_PC command the
1223 * caller should check the request's errors value
1225 scsi_io_completion(cmd
, cmd
->bufflen
, 0);
1228 static void scsi_setup_blk_pc_cmnd(struct scsi_cmnd
*cmd
)
1230 struct request
*req
= cmd
->request
;
1232 BUG_ON(sizeof(req
->cmd
) > sizeof(cmd
->cmnd
));
1233 memcpy(cmd
->cmnd
, req
->cmd
, sizeof(cmd
->cmnd
));
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
;
1244 cmd
->timeout_per_command
= req
->timeout
;
1245 cmd
->done
= scsi_blk_pc_done
;
1248 static int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1250 struct scsi_device
*sdev
= q
->queuedata
;
1251 struct scsi_cmnd
*cmd
;
1252 int specials_only
= 0;
1255 * Just check to see if the device is online. If it isn't, we
1256 * refuse to process any commands. The device must be brought
1257 * online before trying any recovery commands
1259 if (unlikely(!scsi_device_online(sdev
))) {
1260 sdev_printk(KERN_ERR
, sdev
,
1261 "rejecting I/O to offline device\n");
1264 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1265 /* OK, we're not in a running state don't prep
1267 if (sdev
->sdev_state
== SDEV_DEL
) {
1268 /* Device is fully deleted, no commands
1269 * at all allowed down */
1270 sdev_printk(KERN_ERR
, sdev
,
1271 "rejecting I/O to dead device\n");
1274 /* OK, we only allow special commands (i.e. not
1275 * user initiated ones */
1276 specials_only
= sdev
->sdev_state
;
1280 * Find the actual device driver associated with this command.
1281 * The SPECIAL requests are things like character device or
1282 * ioctls, which did not originate from ll_rw_blk. Note that
1283 * the special field is also used to indicate the cmd for
1284 * the remainder of a partially fulfilled request that can
1285 * come up when there is a medium error. We have to treat
1286 * these two cases differently. We differentiate by looking
1287 * at request->cmd, as this tells us the real story.
1289 if (req
->flags
& REQ_SPECIAL
&& req
->special
) {
1290 struct scsi_request
*sreq
= req
->special
;
1292 if (sreq
->sr_magic
== SCSI_REQ_MAGIC
) {
1293 cmd
= scsi_get_command(sreq
->sr_device
, GFP_ATOMIC
);
1296 scsi_init_cmd_from_req(cmd
, sreq
);
1299 } else if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1301 if(unlikely(specials_only
) && !(req
->flags
& REQ_SPECIAL
)) {
1302 if(specials_only
== SDEV_QUIESCE
||
1303 specials_only
== SDEV_BLOCK
)
1306 sdev_printk(KERN_ERR
, sdev
,
1307 "rejecting I/O to device being removed\n");
1313 * Now try and find a command block that we can use.
1315 if (!req
->special
) {
1316 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1322 /* pull a tag out of the request if we have one */
1323 cmd
->tag
= req
->tag
;
1325 blk_dump_rq_flags(req
, "SCSI bad req");
1329 /* note the overloading of req->special. When the tag
1330 * is active it always means cmd. If the tag goes
1331 * back for re-queueing, it may be reset */
1336 * FIXME: drop the lock here because the functions below
1337 * expect to be called without the queue lock held. Also,
1338 * previously, we dequeued the request before dropping the
1339 * lock. We hope REQ_STARTED prevents anything untoward from
1342 if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1346 * This will do a couple of things:
1347 * 1) Fill in the actual SCSI command.
1348 * 2) Fill in any other upper-level specific fields
1351 * If this returns 0, it means that the request failed
1352 * (reading past end of disk, reading offline device,
1353 * etc). This won't actually talk to the device, but
1354 * some kinds of consistency checking may cause the
1355 * request to be rejected immediately.
1359 * This sets up the scatter-gather table (allocating if
1362 ret
= scsi_init_io(cmd
);
1364 /* For BLKPREP_KILL/DEFER the cmd was released */
1372 * Initialize the actual SCSI command for this request.
1374 if (req
->flags
& REQ_BLOCK_PC
) {
1375 scsi_setup_blk_pc_cmnd(cmd
);
1376 } else if (req
->rq_disk
) {
1377 struct scsi_driver
*drv
;
1379 drv
= *(struct scsi_driver
**)req
->rq_disk
->private_data
;
1380 if (unlikely(!drv
->init_command(cmd
))) {
1381 scsi_release_buffers(cmd
);
1382 scsi_put_command(cmd
);
1389 * The request is now prepped, no need to come back here
1391 req
->flags
|= REQ_DONTPREP
;
1395 /* If we defer, the elv_next_request() returns NULL, but the
1396 * queue must be restarted, so we plug here if no returning
1397 * command will automatically do that. */
1398 if (sdev
->device_busy
== 0)
1400 return BLKPREP_DEFER
;
1402 req
->errors
= DID_NO_CONNECT
<< 16;
1403 return BLKPREP_KILL
;
1407 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1410 * Called with the queue_lock held.
1412 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1413 struct scsi_device
*sdev
)
1415 if (sdev
->device_busy
>= sdev
->queue_depth
)
1417 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1419 * unblock after device_blocked iterates to zero
1421 if (--sdev
->device_blocked
== 0) {
1423 sdev_printk(KERN_INFO
, sdev
,
1424 "unblocking device at zero depth\n"));
1430 if (sdev
->device_blocked
)
1437 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1438 * return 0. We must end up running the queue again whenever 0 is
1439 * returned, else IO can hang.
1441 * Called with host_lock held.
1443 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1444 struct Scsi_Host
*shost
,
1445 struct scsi_device
*sdev
)
1447 if (scsi_host_in_recovery(shost
))
1449 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1451 * unblock after host_blocked iterates to zero
1453 if (--shost
->host_blocked
== 0) {
1455 printk("scsi%d unblocking host at zero depth\n",
1462 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
1463 shost
->host_blocked
|| shost
->host_self_blocked
) {
1464 if (list_empty(&sdev
->starved_entry
))
1465 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1469 /* We're OK to process the command, so we can't be starved */
1470 if (!list_empty(&sdev
->starved_entry
))
1471 list_del_init(&sdev
->starved_entry
);
1477 * Kill a request for a dead device
1479 static void scsi_kill_request(struct request
*req
, request_queue_t
*q
)
1481 struct scsi_cmnd
*cmd
= req
->special
;
1483 blkdev_dequeue_request(req
);
1485 if (unlikely(cmd
== NULL
)) {
1486 printk(KERN_CRIT
"impossible request in %s.\n",
1491 scsi_init_cmd_errh(cmd
);
1492 cmd
->result
= DID_NO_CONNECT
<< 16;
1493 atomic_inc(&cmd
->device
->iorequest_cnt
);
1497 static void scsi_softirq_done(struct request
*rq
)
1499 struct scsi_cmnd
*cmd
= rq
->completion_data
;
1500 unsigned long wait_for
= cmd
->allowed
* cmd
->timeout_per_command
;
1503 INIT_LIST_HEAD(&cmd
->eh_entry
);
1505 disposition
= scsi_decide_disposition(cmd
);
1506 if (disposition
!= SUCCESS
&&
1507 time_before(cmd
->jiffies_at_alloc
+ wait_for
, jiffies
)) {
1508 sdev_printk(KERN_ERR
, cmd
->device
,
1509 "timing out command, waited %lus\n",
1511 disposition
= SUCCESS
;
1514 scsi_log_completion(cmd
, disposition
);
1516 switch (disposition
) {
1518 scsi_finish_command(cmd
);
1521 scsi_retry_command(cmd
);
1523 case ADD_TO_MLQUEUE
:
1524 scsi_queue_insert(cmd
, SCSI_MLQUEUE_DEVICE_BUSY
);
1527 if (!scsi_eh_scmd_add(cmd
, 0))
1528 scsi_finish_command(cmd
);
1533 * Function: scsi_request_fn()
1535 * Purpose: Main strategy routine for SCSI.
1537 * Arguments: q - Pointer to actual queue.
1541 * Lock status: IO request lock assumed to be held when called.
1543 static void scsi_request_fn(struct request_queue
*q
)
1545 struct scsi_device
*sdev
= q
->queuedata
;
1546 struct Scsi_Host
*shost
;
1547 struct scsi_cmnd
*cmd
;
1548 struct request
*req
;
1551 printk("scsi: killing requests for dead queue\n");
1552 while ((req
= elv_next_request(q
)) != NULL
)
1553 scsi_kill_request(req
, q
);
1557 if(!get_device(&sdev
->sdev_gendev
))
1558 /* We must be tearing the block queue down already */
1562 * To start with, we keep looping until the queue is empty, or until
1563 * the host is no longer able to accept any more requests.
1566 while (!blk_queue_plugged(q
)) {
1569 * get next queueable request. We do this early to make sure
1570 * that the request is fully prepared even if we cannot
1573 req
= elv_next_request(q
);
1574 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1577 if (unlikely(!scsi_device_online(sdev
))) {
1578 sdev_printk(KERN_ERR
, sdev
,
1579 "rejecting I/O to offline device\n");
1580 scsi_kill_request(req
, q
);
1586 * Remove the request from the request list.
1588 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1589 blkdev_dequeue_request(req
);
1590 sdev
->device_busy
++;
1592 spin_unlock(q
->queue_lock
);
1594 if (unlikely(cmd
== NULL
)) {
1595 printk(KERN_CRIT
"impossible request in %s.\n"
1596 "please mail a stack trace to "
1597 "linux-scsi@vger.kernel.org",
1601 spin_lock(shost
->host_lock
);
1603 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1605 if (sdev
->single_lun
) {
1606 if (scsi_target(sdev
)->starget_sdev_user
&&
1607 scsi_target(sdev
)->starget_sdev_user
!= sdev
)
1609 scsi_target(sdev
)->starget_sdev_user
= sdev
;
1614 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1615 * take the lock again.
1617 spin_unlock_irq(shost
->host_lock
);
1620 * Finally, initialize any error handling parameters, and set up
1621 * the timers for timeouts.
1623 scsi_init_cmd_errh(cmd
);
1626 * Dispatch the command to the low-level driver.
1628 rtn
= scsi_dispatch_cmd(cmd
);
1629 spin_lock_irq(q
->queue_lock
);
1631 /* we're refusing the command; because of
1632 * the way locks get dropped, we need to
1633 * check here if plugging is required */
1634 if(sdev
->device_busy
== 0)
1644 spin_unlock_irq(shost
->host_lock
);
1647 * lock q, handle tag, requeue req, and decrement device_busy. We
1648 * must return with queue_lock held.
1650 * Decrementing device_busy without checking it is OK, as all such
1651 * cases (host limits or settings) should run the queue at some
1654 spin_lock_irq(q
->queue_lock
);
1655 blk_requeue_request(q
, req
);
1656 sdev
->device_busy
--;
1657 if(sdev
->device_busy
== 0)
1660 /* must be careful here...if we trigger the ->remove() function
1661 * we cannot be holding the q lock */
1662 spin_unlock_irq(q
->queue_lock
);
1663 put_device(&sdev
->sdev_gendev
);
1664 spin_lock_irq(q
->queue_lock
);
1667 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1669 struct device
*host_dev
;
1670 u64 bounce_limit
= 0xffffffff;
1672 if (shost
->unchecked_isa_dma
)
1673 return BLK_BOUNCE_ISA
;
1675 * Platforms with virtual-DMA translation
1676 * hardware have no practical limit.
1678 if (!PCI_DMA_BUS_IS_PHYS
)
1679 return BLK_BOUNCE_ANY
;
1681 host_dev
= scsi_get_device(shost
);
1682 if (host_dev
&& host_dev
->dma_mask
)
1683 bounce_limit
= *host_dev
->dma_mask
;
1685 return bounce_limit
;
1687 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1689 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1691 struct Scsi_Host
*shost
= sdev
->host
;
1692 struct request_queue
*q
;
1694 q
= blk_init_queue(scsi_request_fn
, NULL
);
1698 blk_queue_prep_rq(q
, scsi_prep_fn
);
1700 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1701 blk_queue_max_phys_segments(q
, SCSI_MAX_PHYS_SEGMENTS
);
1702 blk_queue_max_sectors(q
, shost
->max_sectors
);
1703 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1704 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1705 blk_queue_issue_flush_fn(q
, scsi_issue_flush_fn
);
1706 blk_queue_softirq_done(q
, scsi_softirq_done
);
1708 if (!shost
->use_clustering
)
1709 clear_bit(QUEUE_FLAG_CLUSTER
, &q
->queue_flags
);
1713 void scsi_free_queue(struct request_queue
*q
)
1715 blk_cleanup_queue(q
);
1719 * Function: scsi_block_requests()
1721 * Purpose: Utility function used by low-level drivers to prevent further
1722 * commands from being queued to the device.
1724 * Arguments: shost - Host in question
1728 * Lock status: No locks are assumed held.
1730 * Notes: There is no timer nor any other means by which the requests
1731 * get unblocked other than the low-level driver calling
1732 * scsi_unblock_requests().
1734 void scsi_block_requests(struct Scsi_Host
*shost
)
1736 shost
->host_self_blocked
= 1;
1738 EXPORT_SYMBOL(scsi_block_requests
);
1741 * Function: scsi_unblock_requests()
1743 * Purpose: Utility function used by low-level drivers to allow further
1744 * commands from being queued to the device.
1746 * Arguments: shost - Host in question
1750 * Lock status: No locks are assumed held.
1752 * Notes: There is no timer nor any other means by which the requests
1753 * get unblocked other than the low-level driver calling
1754 * scsi_unblock_requests().
1756 * This is done as an API function so that changes to the
1757 * internals of the scsi mid-layer won't require wholesale
1758 * changes to drivers that use this feature.
1760 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1762 shost
->host_self_blocked
= 0;
1763 scsi_run_host_queues(shost
);
1765 EXPORT_SYMBOL(scsi_unblock_requests
);
1767 int __init
scsi_init_queue(void)
1771 scsi_io_context_cache
= kmem_cache_create("scsi_io_context",
1772 sizeof(struct scsi_io_context
),
1774 if (!scsi_io_context_cache
) {
1775 printk(KERN_ERR
"SCSI: can't init scsi io context cache\n");
1779 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1780 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1781 int size
= sgp
->size
* sizeof(struct scatterlist
);
1783 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1784 SLAB_HWCACHE_ALIGN
, NULL
, NULL
);
1786 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1790 sgp
->pool
= mempool_create(SG_MEMPOOL_SIZE
,
1791 mempool_alloc_slab
, mempool_free_slab
,
1794 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1802 void scsi_exit_queue(void)
1806 kmem_cache_destroy(scsi_io_context_cache
);
1808 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1809 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1810 mempool_destroy(sgp
->pool
);
1811 kmem_cache_destroy(sgp
->slab
);
1815 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1816 * six bytes if necessary.
1817 * @sdev: SCSI device to be queried
1818 * @dbd: set if mode sense will allow block descriptors to be returned
1819 * @modepage: mode page being requested
1820 * @buffer: request buffer (may not be smaller than eight bytes)
1821 * @len: length of request buffer.
1822 * @timeout: command timeout
1823 * @retries: number of retries before failing
1824 * @data: returns a structure abstracting the mode header data
1825 * @sense: place to put sense data (or NULL if no sense to be collected).
1826 * must be SCSI_SENSE_BUFFERSIZE big.
1828 * Returns zero if unsuccessful, or the header offset (either 4
1829 * or 8 depending on whether a six or ten byte command was
1830 * issued) if successful.
1833 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
1834 unsigned char *buffer
, int len
, int timeout
, int retries
,
1835 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
) {
1836 unsigned char cmd
[12];
1840 struct scsi_sense_hdr my_sshdr
;
1842 memset(data
, 0, sizeof(*data
));
1843 memset(&cmd
[0], 0, 12);
1844 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
1847 /* caller might not be interested in sense, but we need it */
1852 use_10_for_ms
= sdev
->use_10_for_ms
;
1854 if (use_10_for_ms
) {
1858 cmd
[0] = MODE_SENSE_10
;
1865 cmd
[0] = MODE_SENSE
;
1870 memset(buffer
, 0, len
);
1872 result
= scsi_execute_req(sdev
, cmd
, DMA_FROM_DEVICE
, buffer
, len
,
1873 sshdr
, timeout
, retries
);
1875 /* This code looks awful: what it's doing is making sure an
1876 * ILLEGAL REQUEST sense return identifies the actual command
1877 * byte as the problem. MODE_SENSE commands can return
1878 * ILLEGAL REQUEST if the code page isn't supported */
1880 if (use_10_for_ms
&& !scsi_status_is_good(result
) &&
1881 (driver_byte(result
) & DRIVER_SENSE
)) {
1882 if (scsi_sense_valid(sshdr
)) {
1883 if ((sshdr
->sense_key
== ILLEGAL_REQUEST
) &&
1884 (sshdr
->asc
== 0x20) && (sshdr
->ascq
== 0)) {
1886 * Invalid command operation code
1888 sdev
->use_10_for_ms
= 0;
1894 if(scsi_status_is_good(result
)) {
1895 data
->header_length
= header_length
;
1897 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
1898 data
->medium_type
= buffer
[2];
1899 data
->device_specific
= buffer
[3];
1900 data
->longlba
= buffer
[4] & 0x01;
1901 data
->block_descriptor_length
= buffer
[6]*256
1904 data
->length
= buffer
[0] + 1;
1905 data
->medium_type
= buffer
[1];
1906 data
->device_specific
= buffer
[2];
1907 data
->block_descriptor_length
= buffer
[3];
1913 EXPORT_SYMBOL(scsi_mode_sense
);
1916 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
)
1919 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
1921 struct scsi_sense_hdr sshdr
;
1924 result
= scsi_execute_req(sdev
, cmd
, DMA_NONE
, NULL
, 0, &sshdr
,
1927 if ((driver_byte(result
) & DRIVER_SENSE
) && sdev
->removable
) {
1929 if ((scsi_sense_valid(&sshdr
)) &&
1930 ((sshdr
.sense_key
== UNIT_ATTENTION
) ||
1931 (sshdr
.sense_key
== NOT_READY
))) {
1938 EXPORT_SYMBOL(scsi_test_unit_ready
);
1941 * scsi_device_set_state - Take the given device through the device
1943 * @sdev: scsi device to change the state of.
1944 * @state: state to change to.
1946 * Returns zero if unsuccessful or an error if the requested
1947 * transition is illegal.
1950 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
1952 enum scsi_device_state oldstate
= sdev
->sdev_state
;
1954 if (state
== oldstate
)
1959 /* There are no legal states that come back to
1960 * created. This is the manually initialised start
2030 sdev
->sdev_state
= state
;
2034 SCSI_LOG_ERROR_RECOVERY(1,
2035 sdev_printk(KERN_ERR
, sdev
,
2036 "Illegal state transition %s->%s\n",
2037 scsi_device_state_name(oldstate
),
2038 scsi_device_state_name(state
))
2042 EXPORT_SYMBOL(scsi_device_set_state
);
2045 * scsi_device_quiesce - Block user issued commands.
2046 * @sdev: scsi device to quiesce.
2048 * This works by trying to transition to the SDEV_QUIESCE state
2049 * (which must be a legal transition). When the device is in this
2050 * state, only special requests will be accepted, all others will
2051 * be deferred. Since special requests may also be requeued requests,
2052 * a successful return doesn't guarantee the device will be
2053 * totally quiescent.
2055 * Must be called with user context, may sleep.
2057 * Returns zero if unsuccessful or an error if not.
2060 scsi_device_quiesce(struct scsi_device
*sdev
)
2062 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
2066 scsi_run_queue(sdev
->request_queue
);
2067 while (sdev
->device_busy
) {
2068 msleep_interruptible(200);
2069 scsi_run_queue(sdev
->request_queue
);
2073 EXPORT_SYMBOL(scsi_device_quiesce
);
2076 * scsi_device_resume - Restart user issued commands to a quiesced device.
2077 * @sdev: scsi device to resume.
2079 * Moves the device from quiesced back to running and restarts the
2082 * Must be called with user context, may sleep.
2085 scsi_device_resume(struct scsi_device
*sdev
)
2087 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
2089 scsi_run_queue(sdev
->request_queue
);
2091 EXPORT_SYMBOL(scsi_device_resume
);
2094 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
2096 scsi_device_quiesce(sdev
);
2100 scsi_target_quiesce(struct scsi_target
*starget
)
2102 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
2104 EXPORT_SYMBOL(scsi_target_quiesce
);
2107 device_resume_fn(struct scsi_device
*sdev
, void *data
)
2109 scsi_device_resume(sdev
);
2113 scsi_target_resume(struct scsi_target
*starget
)
2115 starget_for_each_device(starget
, NULL
, device_resume_fn
);
2117 EXPORT_SYMBOL(scsi_target_resume
);
2120 * scsi_internal_device_block - internal function to put a device
2121 * temporarily into the SDEV_BLOCK state
2122 * @sdev: device to block
2124 * Block request made by scsi lld's to temporarily stop all
2125 * scsi commands on the specified device. Called from interrupt
2126 * or normal process context.
2128 * Returns zero if successful or error if not
2131 * This routine transitions the device to the SDEV_BLOCK state
2132 * (which must be a legal transition). When the device is in this
2133 * state, all commands are deferred until the scsi lld reenables
2134 * the device with scsi_device_unblock or device_block_tmo fires.
2135 * This routine assumes the host_lock is held on entry.
2138 scsi_internal_device_block(struct scsi_device
*sdev
)
2140 request_queue_t
*q
= sdev
->request_queue
;
2141 unsigned long flags
;
2144 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
2149 * The device has transitioned to SDEV_BLOCK. Stop the
2150 * block layer from calling the midlayer with this device's
2153 spin_lock_irqsave(q
->queue_lock
, flags
);
2155 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2159 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
2162 * scsi_internal_device_unblock - resume a device after a block request
2163 * @sdev: device to resume
2165 * Called by scsi lld's or the midlayer to restart the device queue
2166 * for the previously suspended scsi device. Called from interrupt or
2167 * normal process context.
2169 * Returns zero if successful or error if not.
2172 * This routine transitions the device to the SDEV_RUNNING state
2173 * (which must be a legal transition) allowing the midlayer to
2174 * goose the queue for this device. This routine assumes the
2175 * host_lock is held upon entry.
2178 scsi_internal_device_unblock(struct scsi_device
*sdev
)
2180 request_queue_t
*q
= sdev
->request_queue
;
2182 unsigned long flags
;
2185 * Try to transition the scsi device to SDEV_RUNNING
2186 * and goose the device queue if successful.
2188 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
2192 spin_lock_irqsave(q
->queue_lock
, flags
);
2194 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2198 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
2201 device_block(struct scsi_device
*sdev
, void *data
)
2203 scsi_internal_device_block(sdev
);
2207 target_block(struct device
*dev
, void *data
)
2209 if (scsi_is_target_device(dev
))
2210 starget_for_each_device(to_scsi_target(dev
), NULL
,
2216 scsi_target_block(struct device
*dev
)
2218 if (scsi_is_target_device(dev
))
2219 starget_for_each_device(to_scsi_target(dev
), NULL
,
2222 device_for_each_child(dev
, NULL
, target_block
);
2224 EXPORT_SYMBOL_GPL(scsi_target_block
);
2227 device_unblock(struct scsi_device
*sdev
, void *data
)
2229 scsi_internal_device_unblock(sdev
);
2233 target_unblock(struct device
*dev
, void *data
)
2235 if (scsi_is_target_device(dev
))
2236 starget_for_each_device(to_scsi_target(dev
), NULL
,
2242 scsi_target_unblock(struct device
*dev
)
2244 if (scsi_is_target_device(dev
))
2245 starget_for_each_device(to_scsi_target(dev
), NULL
,
2248 device_for_each_child(dev
, NULL
, target_unblock
);
2250 EXPORT_SYMBOL_GPL(scsi_target_unblock
);