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
68 * Function: scsi_insert_special_req()
70 * Purpose: Insert pre-formed request into request queue.
72 * Arguments: sreq - request that is ready to be queued.
73 * at_head - boolean. True if we should insert at head
74 * of queue, false if we should insert at tail.
76 * Lock status: Assumed that lock is not held upon entry.
80 * Notes: This function is called from character device and from
81 * ioctl types of functions where the caller knows exactly
82 * what SCSI command needs to be issued. The idea is that
83 * we merely inject the command into the queue (at the head
84 * for now), and then call the queue request function to actually
87 int scsi_insert_special_req(struct scsi_request
*sreq
, int at_head
)
90 * Because users of this function are apt to reuse requests with no
91 * modification, we have to sanitise the request flags here
93 sreq
->sr_request
->flags
&= ~REQ_DONTPREP
;
94 blk_insert_request(sreq
->sr_device
->request_queue
, sreq
->sr_request
,
99 static void scsi_run_queue(struct request_queue
*q
);
100 static void scsi_release_buffers(struct scsi_cmnd
*cmd
);
103 * Function: scsi_unprep_request()
105 * Purpose: Remove all preparation done for a request, including its
106 * associated scsi_cmnd, so that it can be requeued.
108 * Arguments: req - request to unprepare
110 * Lock status: Assumed that no locks are held upon entry.
114 static void scsi_unprep_request(struct request
*req
)
116 struct scsi_cmnd
*cmd
= req
->special
;
118 req
->flags
&= ~REQ_DONTPREP
;
119 req
->special
= (req
->flags
& REQ_SPECIAL
) ? cmd
->sc_request
: NULL
;
121 scsi_release_buffers(cmd
);
122 scsi_put_command(cmd
);
126 * Function: scsi_queue_insert()
128 * Purpose: Insert a command in the midlevel queue.
130 * Arguments: cmd - command that we are adding to queue.
131 * reason - why we are inserting command to queue.
133 * Lock status: Assumed that lock is not held upon entry.
137 * Notes: We do this for one of two cases. Either the host is busy
138 * and it cannot accept any more commands for the time being,
139 * or the device returned QUEUE_FULL and can accept no more
141 * Notes: This could be called either from an interrupt context or a
142 * normal process context.
144 int scsi_queue_insert(struct scsi_cmnd
*cmd
, int reason
)
146 struct Scsi_Host
*host
= cmd
->device
->host
;
147 struct scsi_device
*device
= cmd
->device
;
148 struct request_queue
*q
= device
->request_queue
;
152 printk("Inserting command %p into mlqueue\n", cmd
));
155 * Set the appropriate busy bit for the device/host.
157 * If the host/device isn't busy, assume that something actually
158 * completed, and that we should be able to queue a command now.
160 * Note that the prior mid-layer assumption that any host could
161 * always queue at least one command is now broken. The mid-layer
162 * will implement a user specifiable stall (see
163 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
164 * if a command is requeued with no other commands outstanding
165 * either for the device or for the host.
167 if (reason
== SCSI_MLQUEUE_HOST_BUSY
)
168 host
->host_blocked
= host
->max_host_blocked
;
169 else if (reason
== SCSI_MLQUEUE_DEVICE_BUSY
)
170 device
->device_blocked
= device
->max_device_blocked
;
173 * Decrement the counters, since these commands are no longer
174 * active on the host/device.
176 scsi_device_unbusy(device
);
179 * Requeue this command. It will go before all other commands
180 * that are already in the queue.
182 * NOTE: there is magic here about the way the queue is plugged if
183 * we have no outstanding commands.
185 * Although we *don't* plug the queue, we call the request
186 * function. The SCSI request function detects the blocked condition
187 * and plugs the queue appropriately.
189 spin_lock_irqsave(q
->queue_lock
, flags
);
190 blk_requeue_request(q
, cmd
->request
);
191 spin_unlock_irqrestore(q
->queue_lock
, flags
);
199 * Function: scsi_do_req
201 * Purpose: Queue a SCSI request
203 * Arguments: sreq - command descriptor.
204 * cmnd - actual SCSI command to be performed.
205 * buffer - data buffer.
206 * bufflen - size of data buffer.
207 * done - completion function to be run.
208 * timeout - how long to let it run before timeout.
209 * retries - number of retries we allow.
211 * Lock status: No locks held upon entry.
215 * Notes: This function is only used for queueing requests for things
216 * like ioctls and character device requests - this is because
217 * we essentially just inject a request into the queue for the
220 * In order to support the scsi_device_quiesce function, we
221 * now inject requests on the *head* of the device queue
222 * rather than the tail.
224 void scsi_do_req(struct scsi_request
*sreq
, const void *cmnd
,
225 void *buffer
, unsigned bufflen
,
226 void (*done
)(struct scsi_cmnd
*),
227 int timeout
, int retries
)
230 * If the upper level driver is reusing these things, then
231 * we should release the low-level block now. Another one will
232 * be allocated later when this request is getting queued.
234 __scsi_release_request(sreq
);
237 * Our own function scsi_done (which marks the host as not busy,
238 * disables the timeout counter, etc) will be called by us or by the
239 * scsi_hosts[host].queuecommand() function needs to also call
240 * the completion function for the high level driver.
242 memcpy(sreq
->sr_cmnd
, cmnd
, sizeof(sreq
->sr_cmnd
));
243 sreq
->sr_bufflen
= bufflen
;
244 sreq
->sr_buffer
= buffer
;
245 sreq
->sr_allowed
= retries
;
246 sreq
->sr_done
= done
;
247 sreq
->sr_timeout_per_command
= timeout
;
249 if (sreq
->sr_cmd_len
== 0)
250 sreq
->sr_cmd_len
= COMMAND_SIZE(sreq
->sr_cmnd
[0]);
253 * head injection *required* here otherwise quiesce won't work
255 scsi_insert_special_req(sreq
, 1);
257 EXPORT_SYMBOL(scsi_do_req
);
259 /* This is the end routine we get to if a command was never attached
260 * to the request. Simply complete the request without changing
261 * rq_status; this will cause a DRIVER_ERROR. */
262 static void scsi_wait_req_end_io(struct request
*req
)
264 BUG_ON(!req
->waiting
);
266 complete(req
->waiting
);
269 void scsi_wait_req(struct scsi_request
*sreq
, const void *cmnd
, void *buffer
,
270 unsigned bufflen
, int timeout
, int retries
)
272 DECLARE_COMPLETION(wait
);
273 int write
= (sreq
->sr_data_direction
== DMA_TO_DEVICE
);
276 req
= blk_get_request(sreq
->sr_device
->request_queue
, write
,
278 if (bufflen
&& blk_rq_map_kern(sreq
->sr_device
->request_queue
, req
,
279 buffer
, bufflen
, __GFP_WAIT
)) {
280 sreq
->sr_result
= DRIVER_ERROR
<< 24;
281 blk_put_request(req
);
285 req
->flags
|= REQ_NOMERGE
;
286 req
->waiting
= &wait
;
287 req
->end_io
= scsi_wait_req_end_io
;
288 req
->cmd_len
= COMMAND_SIZE(((u8
*)cmnd
)[0]);
289 req
->sense
= sreq
->sr_sense_buffer
;
291 memcpy(req
->cmd
, cmnd
, req
->cmd_len
);
292 req
->timeout
= timeout
;
293 req
->flags
|= REQ_BLOCK_PC
;
295 blk_insert_request(sreq
->sr_device
->request_queue
, req
,
296 sreq
->sr_data_direction
== DMA_TO_DEVICE
, NULL
);
297 wait_for_completion(&wait
);
298 sreq
->sr_request
->waiting
= NULL
;
299 sreq
->sr_result
= req
->errors
;
301 sreq
->sr_result
|= (DRIVER_ERROR
<< 24);
303 blk_put_request(req
);
306 EXPORT_SYMBOL(scsi_wait_req
);
309 * scsi_execute - insert request and wait for the result
312 * @data_direction: data direction
313 * @buffer: data buffer
314 * @bufflen: len of buffer
315 * @sense: optional sense buffer
316 * @timeout: request timeout in seconds
317 * @retries: number of times to retry request
318 * @flags: or into request flags;
320 * returns the req->errors value which is the the scsi_cmnd result
323 int scsi_execute(struct scsi_device
*sdev
, const unsigned char *cmd
,
324 int data_direction
, void *buffer
, unsigned bufflen
,
325 unsigned char *sense
, int timeout
, int retries
, int flags
)
328 int write
= (data_direction
== DMA_TO_DEVICE
);
329 int ret
= DRIVER_ERROR
<< 24;
331 req
= blk_get_request(sdev
->request_queue
, write
, __GFP_WAIT
);
333 if (bufflen
&& blk_rq_map_kern(sdev
->request_queue
, req
,
334 buffer
, bufflen
, __GFP_WAIT
))
337 req
->cmd_len
= COMMAND_SIZE(cmd
[0]);
338 memcpy(req
->cmd
, cmd
, req
->cmd_len
);
341 req
->timeout
= timeout
;
342 req
->flags
|= flags
| REQ_BLOCK_PC
| REQ_SPECIAL
| REQ_QUIET
;
345 * head injection *required* here otherwise quiesce won't work
347 blk_execute_rq(req
->q
, NULL
, req
, 1);
351 blk_put_request(req
);
355 EXPORT_SYMBOL(scsi_execute
);
358 int scsi_execute_req(struct scsi_device
*sdev
, const unsigned char *cmd
,
359 int data_direction
, void *buffer
, unsigned bufflen
,
360 struct scsi_sense_hdr
*sshdr
, int timeout
, int retries
)
366 sense
= kmalloc(SCSI_SENSE_BUFFERSIZE
, GFP_NOIO
);
368 return DRIVER_ERROR
<< 24;
369 memset(sense
, 0, SCSI_SENSE_BUFFERSIZE
);
371 result
= scsi_execute(sdev
, cmd
, data_direction
, buffer
, bufflen
,
372 sense
, timeout
, retries
, 0);
374 scsi_normalize_sense(sense
, SCSI_SENSE_BUFFERSIZE
, sshdr
);
379 EXPORT_SYMBOL(scsi_execute_req
);
382 * Function: scsi_init_cmd_errh()
384 * Purpose: Initialize cmd fields related to error handling.
386 * Arguments: cmd - command that is ready to be queued.
390 * Notes: This function has the job of initializing a number of
391 * fields related to error handling. Typically this will
392 * be called once for each command, as required.
394 static int scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
396 cmd
->serial_number
= 0;
398 memset(cmd
->sense_buffer
, 0, sizeof cmd
->sense_buffer
);
400 if (cmd
->cmd_len
== 0)
401 cmd
->cmd_len
= COMMAND_SIZE(cmd
->cmnd
[0]);
404 * We need saved copies of a number of fields - this is because
405 * error handling may need to overwrite these with different values
406 * to run different commands, and once error handling is complete,
407 * we will need to restore these values prior to running the actual
410 cmd
->old_use_sg
= cmd
->use_sg
;
411 cmd
->old_cmd_len
= cmd
->cmd_len
;
412 cmd
->sc_old_data_direction
= cmd
->sc_data_direction
;
413 cmd
->old_underflow
= cmd
->underflow
;
414 memcpy(cmd
->data_cmnd
, cmd
->cmnd
, sizeof(cmd
->cmnd
));
415 cmd
->buffer
= cmd
->request_buffer
;
416 cmd
->bufflen
= cmd
->request_bufflen
;
422 * Function: scsi_setup_cmd_retry()
424 * Purpose: Restore the command state for a retry
426 * Arguments: cmd - command to be restored
430 * Notes: Immediately prior to retrying a command, we need
431 * to restore certain fields that we saved above.
433 void scsi_setup_cmd_retry(struct scsi_cmnd
*cmd
)
435 memcpy(cmd
->cmnd
, cmd
->data_cmnd
, sizeof(cmd
->data_cmnd
));
436 cmd
->request_buffer
= cmd
->buffer
;
437 cmd
->request_bufflen
= cmd
->bufflen
;
438 cmd
->use_sg
= cmd
->old_use_sg
;
439 cmd
->cmd_len
= cmd
->old_cmd_len
;
440 cmd
->sc_data_direction
= cmd
->sc_old_data_direction
;
441 cmd
->underflow
= cmd
->old_underflow
;
444 void scsi_device_unbusy(struct scsi_device
*sdev
)
446 struct Scsi_Host
*shost
= sdev
->host
;
449 spin_lock_irqsave(shost
->host_lock
, flags
);
451 if (unlikely((shost
->shost_state
== SHOST_RECOVERY
) &&
453 scsi_eh_wakeup(shost
);
454 spin_unlock(shost
->host_lock
);
455 spin_lock(sdev
->request_queue
->queue_lock
);
457 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
461 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
462 * and call blk_run_queue for all the scsi_devices on the target -
463 * including current_sdev first.
465 * Called with *no* scsi locks held.
467 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
469 struct Scsi_Host
*shost
= current_sdev
->host
;
470 struct scsi_device
*sdev
, *tmp
;
471 struct scsi_target
*starget
= scsi_target(current_sdev
);
474 spin_lock_irqsave(shost
->host_lock
, flags
);
475 starget
->starget_sdev_user
= NULL
;
476 spin_unlock_irqrestore(shost
->host_lock
, flags
);
479 * Call blk_run_queue for all LUNs on the target, starting with
480 * current_sdev. We race with others (to set starget_sdev_user),
481 * but in most cases, we will be first. Ideally, each LU on the
482 * target would get some limited time or requests on the target.
484 blk_run_queue(current_sdev
->request_queue
);
486 spin_lock_irqsave(shost
->host_lock
, flags
);
487 if (starget
->starget_sdev_user
)
489 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
490 same_target_siblings
) {
491 if (sdev
== current_sdev
)
493 if (scsi_device_get(sdev
))
496 spin_unlock_irqrestore(shost
->host_lock
, flags
);
497 blk_run_queue(sdev
->request_queue
);
498 spin_lock_irqsave(shost
->host_lock
, flags
);
500 scsi_device_put(sdev
);
503 spin_unlock_irqrestore(shost
->host_lock
, flags
);
507 * Function: scsi_run_queue()
509 * Purpose: Select a proper request queue to serve next
511 * Arguments: q - last request's queue
515 * Notes: The previous command was completely finished, start
516 * a new one if possible.
518 static void scsi_run_queue(struct request_queue
*q
)
520 struct scsi_device
*sdev
= q
->queuedata
;
521 struct Scsi_Host
*shost
= sdev
->host
;
524 if (sdev
->single_lun
)
525 scsi_single_lun_run(sdev
);
527 spin_lock_irqsave(shost
->host_lock
, flags
);
528 while (!list_empty(&shost
->starved_list
) &&
529 !shost
->host_blocked
&& !shost
->host_self_blocked
&&
530 !((shost
->can_queue
> 0) &&
531 (shost
->host_busy
>= shost
->can_queue
))) {
533 * As long as shost is accepting commands and we have
534 * starved queues, call blk_run_queue. scsi_request_fn
535 * drops the queue_lock and can add us back to the
538 * host_lock protects the starved_list and starved_entry.
539 * scsi_request_fn must get the host_lock before checking
540 * or modifying starved_list or starved_entry.
542 sdev
= list_entry(shost
->starved_list
.next
,
543 struct scsi_device
, starved_entry
);
544 list_del_init(&sdev
->starved_entry
);
545 spin_unlock_irqrestore(shost
->host_lock
, flags
);
547 blk_run_queue(sdev
->request_queue
);
549 spin_lock_irqsave(shost
->host_lock
, flags
);
550 if (unlikely(!list_empty(&sdev
->starved_entry
)))
552 * sdev lost a race, and was put back on the
553 * starved list. This is unlikely but without this
554 * in theory we could loop forever.
558 spin_unlock_irqrestore(shost
->host_lock
, flags
);
564 * Function: scsi_requeue_command()
566 * Purpose: Handle post-processing of completed commands.
568 * Arguments: q - queue to operate on
569 * cmd - command that may need to be requeued.
573 * Notes: After command completion, there may be blocks left
574 * over which weren't finished by the previous command
575 * this can be for a number of reasons - the main one is
576 * I/O errors in the middle of the request, in which case
577 * we need to request the blocks that come after the bad
579 * Notes: Upon return, cmd is a stale pointer.
581 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
583 struct request
*req
= cmd
->request
;
586 scsi_unprep_request(req
);
587 spin_lock_irqsave(q
->queue_lock
, flags
);
588 blk_requeue_request(q
, req
);
589 spin_unlock_irqrestore(q
->queue_lock
, flags
);
594 void scsi_next_command(struct scsi_cmnd
*cmd
)
596 struct request_queue
*q
= cmd
->device
->request_queue
;
598 scsi_put_command(cmd
);
602 void scsi_run_host_queues(struct Scsi_Host
*shost
)
604 struct scsi_device
*sdev
;
606 shost_for_each_device(sdev
, shost
)
607 scsi_run_queue(sdev
->request_queue
);
611 * Function: scsi_end_request()
613 * Purpose: Post-processing of completed commands (usually invoked at end
614 * of upper level post-processing and scsi_io_completion).
616 * Arguments: cmd - command that is complete.
617 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
618 * bytes - number of bytes of completed I/O
619 * requeue - indicates whether we should requeue leftovers.
621 * Lock status: Assumed that lock is not held upon entry.
623 * Returns: cmd if requeue required, NULL otherwise.
625 * Notes: This is called for block device requests in order to
626 * mark some number of sectors as complete.
628 * We are guaranteeing that the request queue will be goosed
629 * at some point during this call.
630 * Notes: If cmd was requeued, upon return it will be a stale pointer.
632 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int uptodate
,
633 int bytes
, int requeue
)
635 request_queue_t
*q
= cmd
->device
->request_queue
;
636 struct request
*req
= cmd
->request
;
640 * If there are blocks left over at the end, set up the command
641 * to queue the remainder of them.
643 if (end_that_request_chunk(req
, uptodate
, bytes
)) {
644 int leftover
= (req
->hard_nr_sectors
<< 9);
646 if (blk_pc_request(req
))
647 leftover
= req
->data_len
;
649 /* kill remainder if no retrys */
650 if (!uptodate
&& blk_noretry_request(req
))
651 end_that_request_chunk(req
, 0, leftover
);
655 * Bleah. Leftovers again. Stick the
656 * leftovers in the front of the
657 * queue, and goose the queue again.
659 scsi_requeue_command(q
, cmd
);
666 add_disk_randomness(req
->rq_disk
);
668 spin_lock_irqsave(q
->queue_lock
, flags
);
669 if (blk_rq_tagged(req
))
670 blk_queue_end_tag(q
, req
);
671 end_that_request_last(req
);
672 spin_unlock_irqrestore(q
->queue_lock
, flags
);
675 * This will goose the queue request function at the end, so we don't
676 * need to worry about launching another command.
678 scsi_next_command(cmd
);
682 static struct scatterlist
*scsi_alloc_sgtable(struct scsi_cmnd
*cmd
, int gfp_mask
)
684 struct scsi_host_sg_pool
*sgp
;
685 struct scatterlist
*sgl
;
687 BUG_ON(!cmd
->use_sg
);
689 switch (cmd
->use_sg
) {
699 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
703 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
707 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
718 sgp
= scsi_sg_pools
+ cmd
->sglist_len
;
719 sgl
= mempool_alloc(sgp
->pool
, gfp_mask
);
723 static void scsi_free_sgtable(struct scatterlist
*sgl
, int index
)
725 struct scsi_host_sg_pool
*sgp
;
727 BUG_ON(index
>= SG_MEMPOOL_NR
);
729 sgp
= scsi_sg_pools
+ index
;
730 mempool_free(sgl
, sgp
->pool
);
734 * Function: scsi_release_buffers()
736 * Purpose: Completion processing for block device I/O requests.
738 * Arguments: cmd - command that we are bailing.
740 * Lock status: Assumed that no lock is held upon entry.
744 * Notes: In the event that an upper level driver rejects a
745 * command, we must release resources allocated during
746 * the __init_io() function. Primarily this would involve
747 * the scatter-gather table, and potentially any bounce
750 static void scsi_release_buffers(struct scsi_cmnd
*cmd
)
752 struct request
*req
= cmd
->request
;
755 * Free up any indirection buffers we allocated for DMA purposes.
758 scsi_free_sgtable(cmd
->request_buffer
, cmd
->sglist_len
);
759 else if (cmd
->request_buffer
!= req
->buffer
)
760 kfree(cmd
->request_buffer
);
763 * Zero these out. They now point to freed memory, and it is
764 * dangerous to hang onto the pointers.
768 cmd
->request_buffer
= NULL
;
769 cmd
->request_bufflen
= 0;
773 * Function: scsi_io_completion()
775 * Purpose: Completion processing for block device I/O requests.
777 * Arguments: cmd - command that is finished.
779 * Lock status: Assumed that no lock is held upon entry.
783 * Notes: This function is matched in terms of capabilities to
784 * the function that created the scatter-gather list.
785 * In other words, if there are no bounce buffers
786 * (the normal case for most drivers), we don't need
787 * the logic to deal with cleaning up afterwards.
789 * We must do one of several things here:
791 * a) Call scsi_end_request. This will finish off the
792 * specified number of sectors. If we are done, the
793 * command block will be released, and the queue
794 * function will be goosed. If we are not done, then
795 * scsi_end_request will directly goose the queue.
797 * b) We can just use scsi_requeue_command() here. This would
798 * be used if we just wanted to retry, for example.
800 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
,
801 unsigned int block_bytes
)
803 int result
= cmd
->result
;
804 int this_count
= cmd
->bufflen
;
805 request_queue_t
*q
= cmd
->device
->request_queue
;
806 struct request
*req
= cmd
->request
;
807 int clear_errors
= 1;
808 struct scsi_sense_hdr sshdr
;
810 int sense_deferred
= 0;
812 if (blk_complete_barrier_rq(q
, req
, good_bytes
>> 9))
816 * Free up any indirection buffers we allocated for DMA purposes.
817 * For the case of a READ, we need to copy the data out of the
818 * bounce buffer and into the real buffer.
821 scsi_free_sgtable(cmd
->buffer
, cmd
->sglist_len
);
822 else if (cmd
->buffer
!= req
->buffer
) {
823 if (rq_data_dir(req
) == READ
) {
825 char *to
= bio_kmap_irq(req
->bio
, &flags
);
826 memcpy(to
, cmd
->buffer
, cmd
->bufflen
);
827 bio_kunmap_irq(to
, &flags
);
833 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
835 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
837 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
838 req
->errors
= result
;
841 if (sense_valid
&& req
->sense
) {
843 * SG_IO wants current and deferred errors
845 int len
= 8 + cmd
->sense_buffer
[7];
847 if (len
> SCSI_SENSE_BUFFERSIZE
)
848 len
= SCSI_SENSE_BUFFERSIZE
;
849 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
850 req
->sense_len
= len
;
853 req
->data_len
= cmd
->resid
;
857 * Zero these out. They now point to freed memory, and it is
858 * dangerous to hang onto the pointers.
862 cmd
->request_buffer
= NULL
;
863 cmd
->request_bufflen
= 0;
866 * Next deal with any sectors which we were able to correctly
869 if (good_bytes
>= 0) {
870 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
871 req
->nr_sectors
, good_bytes
));
872 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd
->use_sg
));
877 * If multiple sectors are requested in one buffer, then
878 * they will have been finished off by the first command.
879 * If not, then we have a multi-buffer command.
881 * If block_bytes != 0, it means we had a medium error
882 * of some sort, and that we want to mark some number of
883 * sectors as not uptodate. Thus we want to inhibit
884 * requeueing right here - we will requeue down below
885 * when we handle the bad sectors.
889 * If the command completed without error, then either
890 * finish off the rest of the command, or start a new one.
892 if (scsi_end_request(cmd
, 1, good_bytes
, result
== 0) == NULL
)
896 * Now, if we were good little boys and girls, Santa left us a request
897 * sense buffer. We can extract information from this, so we
898 * can choose a block to remap, etc.
900 if (sense_valid
&& !sense_deferred
) {
901 switch (sshdr
.sense_key
) {
903 if (cmd
->device
->removable
) {
904 /* detected disc change. set a bit
905 * and quietly refuse further access.
907 cmd
->device
->changed
= 1;
908 scsi_end_request(cmd
, 0,
913 * Must have been a power glitch, or a
914 * bus reset. Could not have been a
915 * media change, so we just retry the
916 * request and see what happens.
918 scsi_requeue_command(q
, cmd
);
922 case ILLEGAL_REQUEST
:
924 * If we had an ILLEGAL REQUEST returned, then we may
925 * have performed an unsupported command. The only
926 * thing this should be would be a ten byte read where
927 * only a six byte read was supported. Also, on a
928 * system where READ CAPACITY failed, we may have read
929 * past the end of the disk.
931 if (cmd
->device
->use_10_for_rw
&&
932 (cmd
->cmnd
[0] == READ_10
||
933 cmd
->cmnd
[0] == WRITE_10
)) {
934 cmd
->device
->use_10_for_rw
= 0;
936 * This will cause a retry with a 6-byte
939 scsi_requeue_command(q
, cmd
);
942 scsi_end_request(cmd
, 0, this_count
, 1);
948 * If the device is in the process of becoming ready,
951 if (sshdr
.asc
== 0x04 && sshdr
.ascq
== 0x01) {
952 scsi_requeue_command(q
, cmd
);
955 if (!(req
->flags
& REQ_QUIET
))
956 dev_printk(KERN_INFO
,
957 &cmd
->device
->sdev_gendev
,
958 "Device not ready.\n");
959 scsi_end_request(cmd
, 0, this_count
, 1);
961 case VOLUME_OVERFLOW
:
962 if (!(req
->flags
& REQ_QUIET
)) {
963 dev_printk(KERN_INFO
,
964 &cmd
->device
->sdev_gendev
,
965 "Volume overflow, CDB: ");
966 __scsi_print_command(cmd
->data_cmnd
);
967 scsi_print_sense("", cmd
);
969 scsi_end_request(cmd
, 0, block_bytes
, 1);
974 } /* driver byte != 0 */
975 if (host_byte(result
) == DID_RESET
) {
977 * Third party bus reset or reset for error
978 * recovery reasons. Just retry the request
979 * and see what happens.
981 scsi_requeue_command(q
, cmd
);
985 if (!(req
->flags
& REQ_QUIET
)) {
986 dev_printk(KERN_INFO
, &cmd
->device
->sdev_gendev
,
987 "SCSI error: return code = 0x%x\n", result
);
989 if (driver_byte(result
) & DRIVER_SENSE
)
990 scsi_print_sense("", cmd
);
993 * Mark a single buffer as not uptodate. Queue the remainder.
994 * We sometimes get this cruft in the event that a medium error
995 * isn't properly reported.
997 block_bytes
= req
->hard_cur_sectors
<< 9;
999 block_bytes
= req
->data_len
;
1000 scsi_end_request(cmd
, 0, block_bytes
, 1);
1003 EXPORT_SYMBOL(scsi_io_completion
);
1006 * Function: scsi_init_io()
1008 * Purpose: SCSI I/O initialize function.
1010 * Arguments: cmd - Command descriptor we wish to initialize
1012 * Returns: 0 on success
1013 * BLKPREP_DEFER if the failure is retryable
1014 * BLKPREP_KILL if the failure is fatal
1016 static int scsi_init_io(struct scsi_cmnd
*cmd
)
1018 struct request
*req
= cmd
->request
;
1019 struct scatterlist
*sgpnt
;
1023 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
1025 if ((req
->flags
& REQ_BLOCK_PC
) && !req
->bio
) {
1026 cmd
->request_bufflen
= req
->data_len
;
1027 cmd
->request_buffer
= req
->data
;
1028 req
->buffer
= req
->data
;
1034 * we used to not use scatter-gather for single segment request,
1035 * but now we do (it makes highmem I/O easier to support without
1038 cmd
->use_sg
= req
->nr_phys_segments
;
1041 * if sg table allocation fails, requeue request later.
1043 sgpnt
= scsi_alloc_sgtable(cmd
, GFP_ATOMIC
);
1044 if (unlikely(!sgpnt
))
1045 return BLKPREP_DEFER
;
1047 cmd
->request_buffer
= (char *) sgpnt
;
1048 cmd
->request_bufflen
= req
->nr_sectors
<< 9;
1049 if (blk_pc_request(req
))
1050 cmd
->request_bufflen
= req
->data_len
;
1054 * Next, walk the list, and fill in the addresses and sizes of
1057 count
= blk_rq_map_sg(req
->q
, req
, cmd
->request_buffer
);
1060 * mapped well, send it off
1062 if (likely(count
<= cmd
->use_sg
)) {
1063 cmd
->use_sg
= count
;
1067 printk(KERN_ERR
"Incorrect number of segments after building list\n");
1068 printk(KERN_ERR
"counted %d, received %d\n", count
, cmd
->use_sg
);
1069 printk(KERN_ERR
"req nr_sec %lu, cur_nr_sec %u\n", req
->nr_sectors
,
1070 req
->current_nr_sectors
);
1072 /* release the command and kill it */
1073 scsi_release_buffers(cmd
);
1074 scsi_put_command(cmd
);
1075 return BLKPREP_KILL
;
1078 static int scsi_prepare_flush_fn(request_queue_t
*q
, struct request
*rq
)
1080 struct scsi_device
*sdev
= q
->queuedata
;
1081 struct scsi_driver
*drv
;
1083 if (sdev
->sdev_state
== SDEV_RUNNING
) {
1084 drv
= *(struct scsi_driver
**) rq
->rq_disk
->private_data
;
1086 if (drv
->prepare_flush
)
1087 return drv
->prepare_flush(q
, rq
);
1093 static void scsi_end_flush_fn(request_queue_t
*q
, struct request
*rq
)
1095 struct scsi_device
*sdev
= q
->queuedata
;
1096 struct request
*flush_rq
= rq
->end_io_data
;
1097 struct scsi_driver
*drv
;
1099 if (flush_rq
->errors
) {
1100 printk("scsi: barrier error, disabling flush support\n");
1101 blk_queue_ordered(q
, QUEUE_ORDERED_NONE
);
1104 if (sdev
->sdev_state
== SDEV_RUNNING
) {
1105 drv
= *(struct scsi_driver
**) rq
->rq_disk
->private_data
;
1106 drv
->end_flush(q
, rq
);
1110 static int scsi_issue_flush_fn(request_queue_t
*q
, struct gendisk
*disk
,
1111 sector_t
*error_sector
)
1113 struct scsi_device
*sdev
= q
->queuedata
;
1114 struct scsi_driver
*drv
;
1116 if (sdev
->sdev_state
!= SDEV_RUNNING
)
1119 drv
= *(struct scsi_driver
**) disk
->private_data
;
1120 if (drv
->issue_flush
)
1121 return drv
->issue_flush(&sdev
->sdev_gendev
, error_sector
);
1126 static void scsi_generic_done(struct scsi_cmnd
*cmd
)
1128 BUG_ON(!blk_pc_request(cmd
->request
));
1129 scsi_io_completion(cmd
, cmd
->result
== 0 ? cmd
->bufflen
: 0, 0);
1132 static int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1134 struct scsi_device
*sdev
= q
->queuedata
;
1135 struct scsi_cmnd
*cmd
;
1136 int specials_only
= 0;
1139 * Just check to see if the device is online. If it isn't, we
1140 * refuse to process any commands. The device must be brought
1141 * online before trying any recovery commands
1143 if (unlikely(!scsi_device_online(sdev
))) {
1144 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to offline device\n",
1145 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1148 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1149 /* OK, we're not in a running state don't prep
1151 if (sdev
->sdev_state
== SDEV_DEL
) {
1152 /* Device is fully deleted, no commands
1153 * at all allowed down */
1154 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to dead device\n",
1155 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1158 /* OK, we only allow special commands (i.e. not
1159 * user initiated ones */
1160 specials_only
= sdev
->sdev_state
;
1164 * Find the actual device driver associated with this command.
1165 * The SPECIAL requests are things like character device or
1166 * ioctls, which did not originate from ll_rw_blk. Note that
1167 * the special field is also used to indicate the cmd for
1168 * the remainder of a partially fulfilled request that can
1169 * come up when there is a medium error. We have to treat
1170 * these two cases differently. We differentiate by looking
1171 * at request->cmd, as this tells us the real story.
1173 if (req
->flags
& REQ_SPECIAL
&& req
->special
) {
1174 struct scsi_request
*sreq
= req
->special
;
1176 if (sreq
->sr_magic
== SCSI_REQ_MAGIC
) {
1177 cmd
= scsi_get_command(sreq
->sr_device
, GFP_ATOMIC
);
1180 scsi_init_cmd_from_req(cmd
, sreq
);
1183 } else if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1185 if(unlikely(specials_only
) && !(req
->flags
& REQ_SPECIAL
)) {
1186 if(specials_only
== SDEV_QUIESCE
||
1187 specials_only
== SDEV_BLOCK
)
1190 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to device being removed\n",
1191 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1197 * Now try and find a command block that we can use.
1199 if (!req
->special
) {
1200 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1206 /* pull a tag out of the request if we have one */
1207 cmd
->tag
= req
->tag
;
1209 blk_dump_rq_flags(req
, "SCSI bad req");
1213 /* note the overloading of req->special. When the tag
1214 * is active it always means cmd. If the tag goes
1215 * back for re-queueing, it may be reset */
1220 * FIXME: drop the lock here because the functions below
1221 * expect to be called without the queue lock held. Also,
1222 * previously, we dequeued the request before dropping the
1223 * lock. We hope REQ_STARTED prevents anything untoward from
1226 if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1227 struct scsi_driver
*drv
;
1231 * This will do a couple of things:
1232 * 1) Fill in the actual SCSI command.
1233 * 2) Fill in any other upper-level specific fields
1236 * If this returns 0, it means that the request failed
1237 * (reading past end of disk, reading offline device,
1238 * etc). This won't actually talk to the device, but
1239 * some kinds of consistency checking may cause the
1240 * request to be rejected immediately.
1244 * This sets up the scatter-gather table (allocating if
1247 ret
= scsi_init_io(cmd
);
1250 /* BLKPREP_KILL return also releases the command */
1257 * Initialize the actual SCSI command for this request.
1260 drv
= *(struct scsi_driver
**)req
->rq_disk
->private_data
;
1261 if (unlikely(!drv
->init_command(cmd
))) {
1262 scsi_release_buffers(cmd
);
1263 scsi_put_command(cmd
);
1267 memcpy(cmd
->cmnd
, req
->cmd
, sizeof(cmd
->cmnd
));
1268 cmd
->cmd_len
= req
->cmd_len
;
1269 if (rq_data_dir(req
) == WRITE
)
1270 cmd
->sc_data_direction
= DMA_TO_DEVICE
;
1271 else if (req
->data_len
)
1272 cmd
->sc_data_direction
= DMA_FROM_DEVICE
;
1274 cmd
->sc_data_direction
= DMA_NONE
;
1276 cmd
->transfersize
= req
->data_len
;
1278 cmd
->timeout_per_command
= req
->timeout
;
1279 cmd
->done
= scsi_generic_done
;
1284 * The request is now prepped, no need to come back here
1286 req
->flags
|= REQ_DONTPREP
;
1290 /* If we defer, the elv_next_request() returns NULL, but the
1291 * queue must be restarted, so we plug here if no returning
1292 * command will automatically do that. */
1293 if (sdev
->device_busy
== 0)
1295 return BLKPREP_DEFER
;
1297 req
->errors
= DID_NO_CONNECT
<< 16;
1298 return BLKPREP_KILL
;
1302 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1305 * Called with the queue_lock held.
1307 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1308 struct scsi_device
*sdev
)
1310 if (sdev
->device_busy
>= sdev
->queue_depth
)
1312 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1314 * unblock after device_blocked iterates to zero
1316 if (--sdev
->device_blocked
== 0) {
1318 printk("scsi%d (%d:%d) unblocking device at"
1319 " zero depth\n", sdev
->host
->host_no
,
1320 sdev
->id
, sdev
->lun
));
1326 if (sdev
->device_blocked
)
1333 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1334 * return 0. We must end up running the queue again whenever 0 is
1335 * returned, else IO can hang.
1337 * Called with host_lock held.
1339 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1340 struct Scsi_Host
*shost
,
1341 struct scsi_device
*sdev
)
1343 if (shost
->shost_state
== SHOST_RECOVERY
)
1345 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1347 * unblock after host_blocked iterates to zero
1349 if (--shost
->host_blocked
== 0) {
1351 printk("scsi%d unblocking host at zero depth\n",
1358 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
1359 shost
->host_blocked
|| shost
->host_self_blocked
) {
1360 if (list_empty(&sdev
->starved_entry
))
1361 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1365 /* We're OK to process the command, so we can't be starved */
1366 if (!list_empty(&sdev
->starved_entry
))
1367 list_del_init(&sdev
->starved_entry
);
1373 * Kill a request for a dead device
1375 static void scsi_kill_request(struct request
*req
, request_queue_t
*q
)
1377 struct scsi_cmnd
*cmd
= req
->special
;
1379 blkdev_dequeue_request(req
);
1381 if (unlikely(cmd
== NULL
)) {
1382 printk(KERN_CRIT
"impossible request in %s.\n",
1387 scsi_init_cmd_errh(cmd
);
1388 cmd
->result
= DID_NO_CONNECT
<< 16;
1389 atomic_inc(&cmd
->device
->iorequest_cnt
);
1394 * Function: scsi_request_fn()
1396 * Purpose: Main strategy routine for SCSI.
1398 * Arguments: q - Pointer to actual queue.
1402 * Lock status: IO request lock assumed to be held when called.
1404 static void scsi_request_fn(struct request_queue
*q
)
1406 struct scsi_device
*sdev
= q
->queuedata
;
1407 struct Scsi_Host
*shost
;
1408 struct scsi_cmnd
*cmd
;
1409 struct request
*req
;
1412 printk("scsi: killing requests for dead queue\n");
1413 while ((req
= elv_next_request(q
)) != NULL
)
1414 scsi_kill_request(req
, q
);
1418 if(!get_device(&sdev
->sdev_gendev
))
1419 /* We must be tearing the block queue down already */
1423 * To start with, we keep looping until the queue is empty, or until
1424 * the host is no longer able to accept any more requests.
1427 while (!blk_queue_plugged(q
)) {
1430 * get next queueable request. We do this early to make sure
1431 * that the request is fully prepared even if we cannot
1434 req
= elv_next_request(q
);
1435 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1438 if (unlikely(!scsi_device_online(sdev
))) {
1439 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to offline device\n",
1440 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1441 scsi_kill_request(req
, q
);
1447 * Remove the request from the request list.
1449 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1450 blkdev_dequeue_request(req
);
1451 sdev
->device_busy
++;
1453 spin_unlock(q
->queue_lock
);
1455 if (unlikely(cmd
== NULL
)) {
1456 printk(KERN_CRIT
"impossible request in %s.\n"
1457 "please mail a stack trace to "
1458 "linux-scsi@vger.kernel.org",
1462 spin_lock(shost
->host_lock
);
1464 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1466 if (sdev
->single_lun
) {
1467 if (scsi_target(sdev
)->starget_sdev_user
&&
1468 scsi_target(sdev
)->starget_sdev_user
!= sdev
)
1470 scsi_target(sdev
)->starget_sdev_user
= sdev
;
1475 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1476 * take the lock again.
1478 spin_unlock_irq(shost
->host_lock
);
1481 * Finally, initialize any error handling parameters, and set up
1482 * the timers for timeouts.
1484 scsi_init_cmd_errh(cmd
);
1487 * Dispatch the command to the low-level driver.
1489 rtn
= scsi_dispatch_cmd(cmd
);
1490 spin_lock_irq(q
->queue_lock
);
1492 /* we're refusing the command; because of
1493 * the way locks get dropped, we need to
1494 * check here if plugging is required */
1495 if(sdev
->device_busy
== 0)
1505 spin_unlock_irq(shost
->host_lock
);
1508 * lock q, handle tag, requeue req, and decrement device_busy. We
1509 * must return with queue_lock held.
1511 * Decrementing device_busy without checking it is OK, as all such
1512 * cases (host limits or settings) should run the queue at some
1515 scsi_unprep_request(req
);
1516 spin_lock_irq(q
->queue_lock
);
1517 blk_requeue_request(q
, req
);
1518 sdev
->device_busy
--;
1519 if(sdev
->device_busy
== 0)
1522 /* must be careful here...if we trigger the ->remove() function
1523 * we cannot be holding the q lock */
1524 spin_unlock_irq(q
->queue_lock
);
1525 put_device(&sdev
->sdev_gendev
);
1526 spin_lock_irq(q
->queue_lock
);
1529 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1531 struct device
*host_dev
;
1532 u64 bounce_limit
= 0xffffffff;
1534 if (shost
->unchecked_isa_dma
)
1535 return BLK_BOUNCE_ISA
;
1537 * Platforms with virtual-DMA translation
1538 * hardware have no practical limit.
1540 if (!PCI_DMA_BUS_IS_PHYS
)
1541 return BLK_BOUNCE_ANY
;
1543 host_dev
= scsi_get_device(shost
);
1544 if (host_dev
&& host_dev
->dma_mask
)
1545 bounce_limit
= *host_dev
->dma_mask
;
1547 return bounce_limit
;
1549 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1551 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1553 struct Scsi_Host
*shost
= sdev
->host
;
1554 struct request_queue
*q
;
1556 q
= blk_init_queue(scsi_request_fn
, NULL
);
1560 blk_queue_prep_rq(q
, scsi_prep_fn
);
1562 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1563 blk_queue_max_phys_segments(q
, SCSI_MAX_PHYS_SEGMENTS
);
1564 blk_queue_max_sectors(q
, shost
->max_sectors
);
1565 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1566 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1567 blk_queue_issue_flush_fn(q
, scsi_issue_flush_fn
);
1570 * ordered tags are superior to flush ordering
1572 if (shost
->ordered_tag
)
1573 blk_queue_ordered(q
, QUEUE_ORDERED_TAG
);
1574 else if (shost
->ordered_flush
) {
1575 blk_queue_ordered(q
, QUEUE_ORDERED_FLUSH
);
1576 q
->prepare_flush_fn
= scsi_prepare_flush_fn
;
1577 q
->end_flush_fn
= scsi_end_flush_fn
;
1580 if (!shost
->use_clustering
)
1581 clear_bit(QUEUE_FLAG_CLUSTER
, &q
->queue_flags
);
1585 void scsi_free_queue(struct request_queue
*q
)
1587 blk_cleanup_queue(q
);
1591 * Function: scsi_block_requests()
1593 * Purpose: Utility function used by low-level drivers to prevent further
1594 * commands from being queued to the device.
1596 * Arguments: shost - Host in question
1600 * Lock status: No locks are assumed held.
1602 * Notes: There is no timer nor any other means by which the requests
1603 * get unblocked other than the low-level driver calling
1604 * scsi_unblock_requests().
1606 void scsi_block_requests(struct Scsi_Host
*shost
)
1608 shost
->host_self_blocked
= 1;
1610 EXPORT_SYMBOL(scsi_block_requests
);
1613 * Function: scsi_unblock_requests()
1615 * Purpose: Utility function used by low-level drivers to allow further
1616 * commands from being queued to the device.
1618 * Arguments: shost - Host in question
1622 * Lock status: No locks are assumed held.
1624 * Notes: There is no timer nor any other means by which the requests
1625 * get unblocked other than the low-level driver calling
1626 * scsi_unblock_requests().
1628 * This is done as an API function so that changes to the
1629 * internals of the scsi mid-layer won't require wholesale
1630 * changes to drivers that use this feature.
1632 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1634 shost
->host_self_blocked
= 0;
1635 scsi_run_host_queues(shost
);
1637 EXPORT_SYMBOL(scsi_unblock_requests
);
1639 int __init
scsi_init_queue(void)
1643 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1644 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1645 int size
= sgp
->size
* sizeof(struct scatterlist
);
1647 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1648 SLAB_HWCACHE_ALIGN
, NULL
, NULL
);
1650 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1654 sgp
->pool
= mempool_create(SG_MEMPOOL_SIZE
,
1655 mempool_alloc_slab
, mempool_free_slab
,
1658 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1666 void scsi_exit_queue(void)
1670 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1671 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1672 mempool_destroy(sgp
->pool
);
1673 kmem_cache_destroy(sgp
->slab
);
1677 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1678 * six bytes if necessary.
1679 * @sdev: SCSI device to be queried
1680 * @dbd: set if mode sense will allow block descriptors to be returned
1681 * @modepage: mode page being requested
1682 * @buffer: request buffer (may not be smaller than eight bytes)
1683 * @len: length of request buffer.
1684 * @timeout: command timeout
1685 * @retries: number of retries before failing
1686 * @data: returns a structure abstracting the mode header data
1687 * @sense: place to put sense data (or NULL if no sense to be collected).
1688 * must be SCSI_SENSE_BUFFERSIZE big.
1690 * Returns zero if unsuccessful, or the header offset (either 4
1691 * or 8 depending on whether a six or ten byte command was
1692 * issued) if successful.
1695 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
1696 unsigned char *buffer
, int len
, int timeout
, int retries
,
1697 struct scsi_mode_data
*data
, struct scsi_sense_hdr
*sshdr
) {
1698 unsigned char cmd
[12];
1702 struct scsi_sense_hdr my_sshdr
;
1704 memset(data
, 0, sizeof(*data
));
1705 memset(&cmd
[0], 0, 12);
1706 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
1709 /* caller might not be interested in sense, but we need it */
1714 use_10_for_ms
= sdev
->use_10_for_ms
;
1716 if (use_10_for_ms
) {
1720 cmd
[0] = MODE_SENSE_10
;
1727 cmd
[0] = MODE_SENSE
;
1732 memset(buffer
, 0, len
);
1734 result
= scsi_execute_req(sdev
, cmd
, DMA_FROM_DEVICE
, buffer
, len
,
1735 sshdr
, timeout
, retries
);
1737 /* This code looks awful: what it's doing is making sure an
1738 * ILLEGAL REQUEST sense return identifies the actual command
1739 * byte as the problem. MODE_SENSE commands can return
1740 * ILLEGAL REQUEST if the code page isn't supported */
1742 if (use_10_for_ms
&& !scsi_status_is_good(result
) &&
1743 (driver_byte(result
) & DRIVER_SENSE
)) {
1744 if (scsi_sense_valid(sshdr
)) {
1745 if ((sshdr
->sense_key
== ILLEGAL_REQUEST
) &&
1746 (sshdr
->asc
== 0x20) && (sshdr
->ascq
== 0)) {
1748 * Invalid command operation code
1750 sdev
->use_10_for_ms
= 0;
1756 if(scsi_status_is_good(result
)) {
1757 data
->header_length
= header_length
;
1759 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
1760 data
->medium_type
= buffer
[2];
1761 data
->device_specific
= buffer
[3];
1762 data
->longlba
= buffer
[4] & 0x01;
1763 data
->block_descriptor_length
= buffer
[6]*256
1766 data
->length
= buffer
[0] + 1;
1767 data
->medium_type
= buffer
[1];
1768 data
->device_specific
= buffer
[2];
1769 data
->block_descriptor_length
= buffer
[3];
1775 EXPORT_SYMBOL(scsi_mode_sense
);
1778 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
)
1781 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
1783 struct scsi_sense_hdr sshdr
;
1786 result
= scsi_execute_req(sdev
, cmd
, DMA_NONE
, NULL
, 0, &sshdr
,
1789 if ((driver_byte(result
) & DRIVER_SENSE
) && sdev
->removable
) {
1791 if ((scsi_sense_valid(&sshdr
)) &&
1792 ((sshdr
.sense_key
== UNIT_ATTENTION
) ||
1793 (sshdr
.sense_key
== NOT_READY
))) {
1800 EXPORT_SYMBOL(scsi_test_unit_ready
);
1803 * scsi_device_set_state - Take the given device through the device
1805 * @sdev: scsi device to change the state of.
1806 * @state: state to change to.
1808 * Returns zero if unsuccessful or an error if the requested
1809 * transition is illegal.
1812 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
1814 enum scsi_device_state oldstate
= sdev
->sdev_state
;
1816 if (state
== oldstate
)
1821 /* There are no legal states that come back to
1822 * created. This is the manually initialised start
1892 sdev
->sdev_state
= state
;
1896 SCSI_LOG_ERROR_RECOVERY(1,
1897 dev_printk(KERN_ERR
, &sdev
->sdev_gendev
,
1898 "Illegal state transition %s->%s\n",
1899 scsi_device_state_name(oldstate
),
1900 scsi_device_state_name(state
))
1904 EXPORT_SYMBOL(scsi_device_set_state
);
1907 * scsi_device_quiesce - Block user issued commands.
1908 * @sdev: scsi device to quiesce.
1910 * This works by trying to transition to the SDEV_QUIESCE state
1911 * (which must be a legal transition). When the device is in this
1912 * state, only special requests will be accepted, all others will
1913 * be deferred. Since special requests may also be requeued requests,
1914 * a successful return doesn't guarantee the device will be
1915 * totally quiescent.
1917 * Must be called with user context, may sleep.
1919 * Returns zero if unsuccessful or an error if not.
1922 scsi_device_quiesce(struct scsi_device
*sdev
)
1924 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
1928 scsi_run_queue(sdev
->request_queue
);
1929 while (sdev
->device_busy
) {
1930 msleep_interruptible(200);
1931 scsi_run_queue(sdev
->request_queue
);
1935 EXPORT_SYMBOL(scsi_device_quiesce
);
1938 * scsi_device_resume - Restart user issued commands to a quiesced device.
1939 * @sdev: scsi device to resume.
1941 * Moves the device from quiesced back to running and restarts the
1944 * Must be called with user context, may sleep.
1947 scsi_device_resume(struct scsi_device
*sdev
)
1949 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
1951 scsi_run_queue(sdev
->request_queue
);
1953 EXPORT_SYMBOL(scsi_device_resume
);
1956 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
1958 scsi_device_quiesce(sdev
);
1962 scsi_target_quiesce(struct scsi_target
*starget
)
1964 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
1966 EXPORT_SYMBOL(scsi_target_quiesce
);
1969 device_resume_fn(struct scsi_device
*sdev
, void *data
)
1971 scsi_device_resume(sdev
);
1975 scsi_target_resume(struct scsi_target
*starget
)
1977 starget_for_each_device(starget
, NULL
, device_resume_fn
);
1979 EXPORT_SYMBOL(scsi_target_resume
);
1982 * scsi_internal_device_block - internal function to put a device
1983 * temporarily into the SDEV_BLOCK state
1984 * @sdev: device to block
1986 * Block request made by scsi lld's to temporarily stop all
1987 * scsi commands on the specified device. Called from interrupt
1988 * or normal process context.
1990 * Returns zero if successful or error if not
1993 * This routine transitions the device to the SDEV_BLOCK state
1994 * (which must be a legal transition). When the device is in this
1995 * state, all commands are deferred until the scsi lld reenables
1996 * the device with scsi_device_unblock or device_block_tmo fires.
1997 * This routine assumes the host_lock is held on entry.
2000 scsi_internal_device_block(struct scsi_device
*sdev
)
2002 request_queue_t
*q
= sdev
->request_queue
;
2003 unsigned long flags
;
2006 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
2011 * The device has transitioned to SDEV_BLOCK. Stop the
2012 * block layer from calling the midlayer with this device's
2015 spin_lock_irqsave(q
->queue_lock
, flags
);
2017 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2021 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
2024 * scsi_internal_device_unblock - resume a device after a block request
2025 * @sdev: device to resume
2027 * Called by scsi lld's or the midlayer to restart the device queue
2028 * for the previously suspended scsi device. Called from interrupt or
2029 * normal process context.
2031 * Returns zero if successful or error if not.
2034 * This routine transitions the device to the SDEV_RUNNING state
2035 * (which must be a legal transition) allowing the midlayer to
2036 * goose the queue for this device. This routine assumes the
2037 * host_lock is held upon entry.
2040 scsi_internal_device_unblock(struct scsi_device
*sdev
)
2042 request_queue_t
*q
= sdev
->request_queue
;
2044 unsigned long flags
;
2047 * Try to transition the scsi device to SDEV_RUNNING
2048 * and goose the device queue if successful.
2050 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
2054 spin_lock_irqsave(q
->queue_lock
, flags
);
2056 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2060 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
2063 device_block(struct scsi_device
*sdev
, void *data
)
2065 scsi_internal_device_block(sdev
);
2069 target_block(struct device
*dev
, void *data
)
2071 if (scsi_is_target_device(dev
))
2072 starget_for_each_device(to_scsi_target(dev
), NULL
,
2078 scsi_target_block(struct device
*dev
)
2080 if (scsi_is_target_device(dev
))
2081 starget_for_each_device(to_scsi_target(dev
), NULL
,
2084 device_for_each_child(dev
, NULL
, target_block
);
2086 EXPORT_SYMBOL_GPL(scsi_target_block
);
2089 device_unblock(struct scsi_device
*sdev
, void *data
)
2091 scsi_internal_device_unblock(sdev
);
2095 target_unblock(struct device
*dev
, void *data
)
2097 if (scsi_is_target_device(dev
))
2098 starget_for_each_device(to_scsi_target(dev
), NULL
,
2104 scsi_target_unblock(struct device
*dev
)
2106 if (scsi_is_target_device(dev
))
2107 starget_for_each_device(to_scsi_target(dev
), NULL
,
2110 device_for_each_child(dev
, NULL
, target_unblock
);
2112 EXPORT_SYMBOL_GPL(scsi_target_unblock
);