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
);
102 * Function: scsi_queue_insert()
104 * Purpose: Insert a command in the midlevel queue.
106 * Arguments: cmd - command that we are adding to queue.
107 * reason - why we are inserting command to queue.
109 * Lock status: Assumed that lock is not held upon entry.
113 * Notes: We do this for one of two cases. Either the host is busy
114 * and it cannot accept any more commands for the time being,
115 * or the device returned QUEUE_FULL and can accept no more
117 * Notes: This could be called either from an interrupt context or a
118 * normal process context.
120 int scsi_queue_insert(struct scsi_cmnd
*cmd
, int reason
)
122 struct Scsi_Host
*host
= cmd
->device
->host
;
123 struct scsi_device
*device
= cmd
->device
;
124 struct request_queue
*q
= device
->request_queue
;
128 printk("Inserting command %p into mlqueue\n", cmd
));
131 * Set the appropriate busy bit for the device/host.
133 * If the host/device isn't busy, assume that something actually
134 * completed, and that we should be able to queue a command now.
136 * Note that the prior mid-layer assumption that any host could
137 * always queue at least one command is now broken. The mid-layer
138 * will implement a user specifiable stall (see
139 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
140 * if a command is requeued with no other commands outstanding
141 * either for the device or for the host.
143 if (reason
== SCSI_MLQUEUE_HOST_BUSY
)
144 host
->host_blocked
= host
->max_host_blocked
;
145 else if (reason
== SCSI_MLQUEUE_DEVICE_BUSY
)
146 device
->device_blocked
= device
->max_device_blocked
;
149 * Decrement the counters, since these commands are no longer
150 * active on the host/device.
152 scsi_device_unbusy(device
);
155 * Requeue this command. It will go before all other commands
156 * that are already in the queue.
158 * NOTE: there is magic here about the way the queue is plugged if
159 * we have no outstanding commands.
161 * Although we *don't* plug the queue, we call the request
162 * function. The SCSI request function detects the blocked condition
163 * and plugs the queue appropriately.
165 spin_lock_irqsave(q
->queue_lock
, flags
);
166 blk_requeue_request(q
, cmd
->request
);
167 spin_unlock_irqrestore(q
->queue_lock
, flags
);
175 * Function: scsi_do_req
177 * Purpose: Queue a SCSI request
179 * Arguments: sreq - command descriptor.
180 * cmnd - actual SCSI command to be performed.
181 * buffer - data buffer.
182 * bufflen - size of data buffer.
183 * done - completion function to be run.
184 * timeout - how long to let it run before timeout.
185 * retries - number of retries we allow.
187 * Lock status: No locks held upon entry.
191 * Notes: This function is only used for queueing requests for things
192 * like ioctls and character device requests - this is because
193 * we essentially just inject a request into the queue for the
196 * In order to support the scsi_device_quiesce function, we
197 * now inject requests on the *head* of the device queue
198 * rather than the tail.
200 void scsi_do_req(struct scsi_request
*sreq
, const void *cmnd
,
201 void *buffer
, unsigned bufflen
,
202 void (*done
)(struct scsi_cmnd
*),
203 int timeout
, int retries
)
206 * If the upper level driver is reusing these things, then
207 * we should release the low-level block now. Another one will
208 * be allocated later when this request is getting queued.
210 __scsi_release_request(sreq
);
213 * Our own function scsi_done (which marks the host as not busy,
214 * disables the timeout counter, etc) will be called by us or by the
215 * scsi_hosts[host].queuecommand() function needs to also call
216 * the completion function for the high level driver.
218 memcpy(sreq
->sr_cmnd
, cmnd
, sizeof(sreq
->sr_cmnd
));
219 sreq
->sr_bufflen
= bufflen
;
220 sreq
->sr_buffer
= buffer
;
221 sreq
->sr_allowed
= retries
;
222 sreq
->sr_done
= done
;
223 sreq
->sr_timeout_per_command
= timeout
;
225 if (sreq
->sr_cmd_len
== 0)
226 sreq
->sr_cmd_len
= COMMAND_SIZE(sreq
->sr_cmnd
[0]);
229 * head injection *required* here otherwise quiesce won't work
231 scsi_insert_special_req(sreq
, 1);
233 EXPORT_SYMBOL(scsi_do_req
);
235 static void scsi_wait_done(struct scsi_cmnd
*cmd
)
237 struct request
*req
= cmd
->request
;
238 struct request_queue
*q
= cmd
->device
->request_queue
;
241 req
->rq_status
= RQ_SCSI_DONE
; /* Busy, but indicate request done */
243 spin_lock_irqsave(q
->queue_lock
, flags
);
244 if (blk_rq_tagged(req
))
245 blk_queue_end_tag(q
, req
);
246 spin_unlock_irqrestore(q
->queue_lock
, flags
);
249 complete(req
->waiting
);
252 /* This is the end routine we get to if a command was never attached
253 * to the request. Simply complete the request without changing
254 * rq_status; this will cause a DRIVER_ERROR. */
255 static void scsi_wait_req_end_io(struct request
*req
)
257 BUG_ON(!req
->waiting
);
259 complete(req
->waiting
);
262 void scsi_wait_req(struct scsi_request
*sreq
, const void *cmnd
, void *buffer
,
263 unsigned bufflen
, int timeout
, int retries
)
265 DECLARE_COMPLETION(wait
);
267 sreq
->sr_request
->waiting
= &wait
;
268 sreq
->sr_request
->rq_status
= RQ_SCSI_BUSY
;
269 sreq
->sr_request
->end_io
= scsi_wait_req_end_io
;
270 scsi_do_req(sreq
, cmnd
, buffer
, bufflen
, scsi_wait_done
,
272 wait_for_completion(&wait
);
273 sreq
->sr_request
->waiting
= NULL
;
274 if (sreq
->sr_request
->rq_status
!= RQ_SCSI_DONE
)
275 sreq
->sr_result
|= (DRIVER_ERROR
<< 24);
277 __scsi_release_request(sreq
);
279 EXPORT_SYMBOL(scsi_wait_req
);
282 * Function: scsi_init_cmd_errh()
284 * Purpose: Initialize cmd fields related to error handling.
286 * Arguments: cmd - command that is ready to be queued.
290 * Notes: This function has the job of initializing a number of
291 * fields related to error handling. Typically this will
292 * be called once for each command, as required.
294 static int scsi_init_cmd_errh(struct scsi_cmnd
*cmd
)
296 cmd
->serial_number
= 0;
298 memset(cmd
->sense_buffer
, 0, sizeof cmd
->sense_buffer
);
300 if (cmd
->cmd_len
== 0)
301 cmd
->cmd_len
= COMMAND_SIZE(cmd
->cmnd
[0]);
304 * We need saved copies of a number of fields - this is because
305 * error handling may need to overwrite these with different values
306 * to run different commands, and once error handling is complete,
307 * we will need to restore these values prior to running the actual
310 cmd
->old_use_sg
= cmd
->use_sg
;
311 cmd
->old_cmd_len
= cmd
->cmd_len
;
312 cmd
->sc_old_data_direction
= cmd
->sc_data_direction
;
313 cmd
->old_underflow
= cmd
->underflow
;
314 memcpy(cmd
->data_cmnd
, cmd
->cmnd
, sizeof(cmd
->cmnd
));
315 cmd
->buffer
= cmd
->request_buffer
;
316 cmd
->bufflen
= cmd
->request_bufflen
;
322 * Function: scsi_setup_cmd_retry()
324 * Purpose: Restore the command state for a retry
326 * Arguments: cmd - command to be restored
330 * Notes: Immediately prior to retrying a command, we need
331 * to restore certain fields that we saved above.
333 void scsi_setup_cmd_retry(struct scsi_cmnd
*cmd
)
335 memcpy(cmd
->cmnd
, cmd
->data_cmnd
, sizeof(cmd
->data_cmnd
));
336 cmd
->request_buffer
= cmd
->buffer
;
337 cmd
->request_bufflen
= cmd
->bufflen
;
338 cmd
->use_sg
= cmd
->old_use_sg
;
339 cmd
->cmd_len
= cmd
->old_cmd_len
;
340 cmd
->sc_data_direction
= cmd
->sc_old_data_direction
;
341 cmd
->underflow
= cmd
->old_underflow
;
344 void scsi_device_unbusy(struct scsi_device
*sdev
)
346 struct Scsi_Host
*shost
= sdev
->host
;
349 spin_lock_irqsave(shost
->host_lock
, flags
);
351 if (unlikely((shost
->shost_state
== SHOST_RECOVERY
) &&
353 scsi_eh_wakeup(shost
);
354 spin_unlock(shost
->host_lock
);
355 spin_lock(sdev
->request_queue
->queue_lock
);
357 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
361 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
362 * and call blk_run_queue for all the scsi_devices on the target -
363 * including current_sdev first.
365 * Called with *no* scsi locks held.
367 static void scsi_single_lun_run(struct scsi_device
*current_sdev
)
369 struct Scsi_Host
*shost
= current_sdev
->host
;
370 struct scsi_device
*sdev
, *tmp
;
371 struct scsi_target
*starget
= scsi_target(current_sdev
);
374 spin_lock_irqsave(shost
->host_lock
, flags
);
375 starget
->starget_sdev_user
= NULL
;
376 spin_unlock_irqrestore(shost
->host_lock
, flags
);
379 * Call blk_run_queue for all LUNs on the target, starting with
380 * current_sdev. We race with others (to set starget_sdev_user),
381 * but in most cases, we will be first. Ideally, each LU on the
382 * target would get some limited time or requests on the target.
384 blk_run_queue(current_sdev
->request_queue
);
386 spin_lock_irqsave(shost
->host_lock
, flags
);
387 if (starget
->starget_sdev_user
)
389 list_for_each_entry_safe(sdev
, tmp
, &starget
->devices
,
390 same_target_siblings
) {
391 if (sdev
== current_sdev
)
393 if (scsi_device_get(sdev
))
396 spin_unlock_irqrestore(shost
->host_lock
, flags
);
397 blk_run_queue(sdev
->request_queue
);
398 spin_lock_irqsave(shost
->host_lock
, flags
);
400 scsi_device_put(sdev
);
403 spin_unlock_irqrestore(shost
->host_lock
, flags
);
407 * Function: scsi_run_queue()
409 * Purpose: Select a proper request queue to serve next
411 * Arguments: q - last request's queue
415 * Notes: The previous command was completely finished, start
416 * a new one if possible.
418 static void scsi_run_queue(struct request_queue
*q
)
420 struct scsi_device
*sdev
= q
->queuedata
;
421 struct Scsi_Host
*shost
= sdev
->host
;
424 if (sdev
->single_lun
)
425 scsi_single_lun_run(sdev
);
427 spin_lock_irqsave(shost
->host_lock
, flags
);
428 while (!list_empty(&shost
->starved_list
) &&
429 !shost
->host_blocked
&& !shost
->host_self_blocked
&&
430 !((shost
->can_queue
> 0) &&
431 (shost
->host_busy
>= shost
->can_queue
))) {
433 * As long as shost is accepting commands and we have
434 * starved queues, call blk_run_queue. scsi_request_fn
435 * drops the queue_lock and can add us back to the
438 * host_lock protects the starved_list and starved_entry.
439 * scsi_request_fn must get the host_lock before checking
440 * or modifying starved_list or starved_entry.
442 sdev
= list_entry(shost
->starved_list
.next
,
443 struct scsi_device
, starved_entry
);
444 list_del_init(&sdev
->starved_entry
);
445 spin_unlock_irqrestore(shost
->host_lock
, flags
);
447 blk_run_queue(sdev
->request_queue
);
449 spin_lock_irqsave(shost
->host_lock
, flags
);
450 if (unlikely(!list_empty(&sdev
->starved_entry
)))
452 * sdev lost a race, and was put back on the
453 * starved list. This is unlikely but without this
454 * in theory we could loop forever.
458 spin_unlock_irqrestore(shost
->host_lock
, flags
);
464 * Function: scsi_requeue_command()
466 * Purpose: Handle post-processing of completed commands.
468 * Arguments: q - queue to operate on
469 * cmd - command that may need to be requeued.
473 * Notes: After command completion, there may be blocks left
474 * over which weren't finished by the previous command
475 * this can be for a number of reasons - the main one is
476 * I/O errors in the middle of the request, in which case
477 * we need to request the blocks that come after the bad
480 static void scsi_requeue_command(struct request_queue
*q
, struct scsi_cmnd
*cmd
)
484 cmd
->request
->flags
&= ~REQ_DONTPREP
;
486 spin_lock_irqsave(q
->queue_lock
, flags
);
487 blk_requeue_request(q
, cmd
->request
);
488 spin_unlock_irqrestore(q
->queue_lock
, flags
);
493 void scsi_next_command(struct scsi_cmnd
*cmd
)
495 struct request_queue
*q
= cmd
->device
->request_queue
;
497 scsi_put_command(cmd
);
501 void scsi_run_host_queues(struct Scsi_Host
*shost
)
503 struct scsi_device
*sdev
;
505 shost_for_each_device(sdev
, shost
)
506 scsi_run_queue(sdev
->request_queue
);
510 * Function: scsi_end_request()
512 * Purpose: Post-processing of completed commands (usually invoked at end
513 * of upper level post-processing and scsi_io_completion).
515 * Arguments: cmd - command that is complete.
516 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
517 * bytes - number of bytes of completed I/O
518 * requeue - indicates whether we should requeue leftovers.
520 * Lock status: Assumed that lock is not held upon entry.
522 * Returns: cmd if requeue done or required, NULL otherwise
524 * Notes: This is called for block device requests in order to
525 * mark some number of sectors as complete.
527 * We are guaranteeing that the request queue will be goosed
528 * at some point during this call.
530 static struct scsi_cmnd
*scsi_end_request(struct scsi_cmnd
*cmd
, int uptodate
,
531 int bytes
, int requeue
)
533 request_queue_t
*q
= cmd
->device
->request_queue
;
534 struct request
*req
= cmd
->request
;
538 * If there are blocks left over at the end, set up the command
539 * to queue the remainder of them.
541 if (end_that_request_chunk(req
, uptodate
, bytes
)) {
542 int leftover
= (req
->hard_nr_sectors
<< 9);
544 if (blk_pc_request(req
))
545 leftover
= req
->data_len
;
547 /* kill remainder if no retrys */
548 if (!uptodate
&& blk_noretry_request(req
))
549 end_that_request_chunk(req
, 0, leftover
);
553 * Bleah. Leftovers again. Stick the
554 * leftovers in the front of the
555 * queue, and goose the queue again.
557 scsi_requeue_command(q
, cmd
);
563 add_disk_randomness(req
->rq_disk
);
565 spin_lock_irqsave(q
->queue_lock
, flags
);
566 if (blk_rq_tagged(req
))
567 blk_queue_end_tag(q
, req
);
568 end_that_request_last(req
);
569 spin_unlock_irqrestore(q
->queue_lock
, flags
);
572 * This will goose the queue request function at the end, so we don't
573 * need to worry about launching another command.
575 scsi_next_command(cmd
);
579 static struct scatterlist
*scsi_alloc_sgtable(struct scsi_cmnd
*cmd
, int gfp_mask
)
581 struct scsi_host_sg_pool
*sgp
;
582 struct scatterlist
*sgl
;
584 BUG_ON(!cmd
->use_sg
);
586 switch (cmd
->use_sg
) {
596 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
600 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
604 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
615 sgp
= scsi_sg_pools
+ cmd
->sglist_len
;
616 sgl
= mempool_alloc(sgp
->pool
, gfp_mask
);
620 static void scsi_free_sgtable(struct scatterlist
*sgl
, int index
)
622 struct scsi_host_sg_pool
*sgp
;
624 BUG_ON(index
>= SG_MEMPOOL_NR
);
626 sgp
= scsi_sg_pools
+ index
;
627 mempool_free(sgl
, sgp
->pool
);
631 * Function: scsi_release_buffers()
633 * Purpose: Completion processing for block device I/O requests.
635 * Arguments: cmd - command that we are bailing.
637 * Lock status: Assumed that no lock is held upon entry.
641 * Notes: In the event that an upper level driver rejects a
642 * command, we must release resources allocated during
643 * the __init_io() function. Primarily this would involve
644 * the scatter-gather table, and potentially any bounce
647 static void scsi_release_buffers(struct scsi_cmnd
*cmd
)
649 struct request
*req
= cmd
->request
;
652 * Free up any indirection buffers we allocated for DMA purposes.
655 scsi_free_sgtable(cmd
->request_buffer
, cmd
->sglist_len
);
656 else if (cmd
->request_buffer
!= req
->buffer
)
657 kfree(cmd
->request_buffer
);
660 * Zero these out. They now point to freed memory, and it is
661 * dangerous to hang onto the pointers.
665 cmd
->request_buffer
= NULL
;
666 cmd
->request_bufflen
= 0;
670 * Function: scsi_io_completion()
672 * Purpose: Completion processing for block device I/O requests.
674 * Arguments: cmd - command that is finished.
676 * Lock status: Assumed that no lock is held upon entry.
680 * Notes: This function is matched in terms of capabilities to
681 * the function that created the scatter-gather list.
682 * In other words, if there are no bounce buffers
683 * (the normal case for most drivers), we don't need
684 * the logic to deal with cleaning up afterwards.
686 * We must do one of several things here:
688 * a) Call scsi_end_request. This will finish off the
689 * specified number of sectors. If we are done, the
690 * command block will be released, and the queue
691 * function will be goosed. If we are not done, then
692 * scsi_end_request will directly goose the queue.
694 * b) We can just use scsi_requeue_command() here. This would
695 * be used if we just wanted to retry, for example.
697 void scsi_io_completion(struct scsi_cmnd
*cmd
, unsigned int good_bytes
,
698 unsigned int block_bytes
)
700 int result
= cmd
->result
;
701 int this_count
= cmd
->bufflen
;
702 request_queue_t
*q
= cmd
->device
->request_queue
;
703 struct request
*req
= cmd
->request
;
704 int clear_errors
= 1;
705 struct scsi_sense_hdr sshdr
;
707 int sense_deferred
= 0;
709 if (blk_complete_barrier_rq(q
, req
, good_bytes
>> 9))
713 * Free up any indirection buffers we allocated for DMA purposes.
714 * For the case of a READ, we need to copy the data out of the
715 * bounce buffer and into the real buffer.
718 scsi_free_sgtable(cmd
->buffer
, cmd
->sglist_len
);
719 else if (cmd
->buffer
!= req
->buffer
) {
720 if (rq_data_dir(req
) == READ
) {
722 char *to
= bio_kmap_irq(req
->bio
, &flags
);
723 memcpy(to
, cmd
->buffer
, cmd
->bufflen
);
724 bio_kunmap_irq(to
, &flags
);
730 sense_valid
= scsi_command_normalize_sense(cmd
, &sshdr
);
732 sense_deferred
= scsi_sense_is_deferred(&sshdr
);
734 if (blk_pc_request(req
)) { /* SG_IO ioctl from block level */
735 req
->errors
= result
;
738 if (sense_valid
&& req
->sense
) {
740 * SG_IO wants current and deferred errors
742 int len
= 8 + cmd
->sense_buffer
[7];
744 if (len
> SCSI_SENSE_BUFFERSIZE
)
745 len
= SCSI_SENSE_BUFFERSIZE
;
746 memcpy(req
->sense
, cmd
->sense_buffer
, len
);
747 req
->sense_len
= len
;
750 req
->data_len
= cmd
->resid
;
754 * Zero these out. They now point to freed memory, and it is
755 * dangerous to hang onto the pointers.
759 cmd
->request_buffer
= NULL
;
760 cmd
->request_bufflen
= 0;
763 * Next deal with any sectors which we were able to correctly
766 if (good_bytes
>= 0) {
767 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
768 req
->nr_sectors
, good_bytes
));
769 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd
->use_sg
));
774 * If multiple sectors are requested in one buffer, then
775 * they will have been finished off by the first command.
776 * If not, then we have a multi-buffer command.
778 * If block_bytes != 0, it means we had a medium error
779 * of some sort, and that we want to mark some number of
780 * sectors as not uptodate. Thus we want to inhibit
781 * requeueing right here - we will requeue down below
782 * when we handle the bad sectors.
784 cmd
= scsi_end_request(cmd
, 1, good_bytes
, result
== 0);
787 * If the command completed without error, then either finish off the
788 * rest of the command, or start a new one.
790 if (result
== 0 || cmd
== NULL
) {
795 * Now, if we were good little boys and girls, Santa left us a request
796 * sense buffer. We can extract information from this, so we
797 * can choose a block to remap, etc.
799 if (sense_valid
&& !sense_deferred
) {
800 switch (sshdr
.sense_key
) {
802 if (cmd
->device
->removable
) {
803 /* detected disc change. set a bit
804 * and quietly refuse further access.
806 cmd
->device
->changed
= 1;
807 cmd
= scsi_end_request(cmd
, 0,
812 * Must have been a power glitch, or a
813 * bus reset. Could not have been a
814 * media change, so we just retry the
815 * request and see what happens.
817 scsi_requeue_command(q
, cmd
);
821 case ILLEGAL_REQUEST
:
823 * If we had an ILLEGAL REQUEST returned, then we may
824 * have performed an unsupported command. The only
825 * thing this should be would be a ten byte read where
826 * only a six byte read was supported. Also, on a
827 * system where READ CAPACITY failed, we may have read
828 * past the end of the disk.
830 if (cmd
->device
->use_10_for_rw
&&
831 (cmd
->cmnd
[0] == READ_10
||
832 cmd
->cmnd
[0] == WRITE_10
)) {
833 cmd
->device
->use_10_for_rw
= 0;
835 * This will cause a retry with a 6-byte
838 scsi_requeue_command(q
, cmd
);
841 cmd
= scsi_end_request(cmd
, 0, this_count
, 1);
847 * If the device is in the process of becoming ready,
850 if (sshdr
.asc
== 0x04 && sshdr
.ascq
== 0x01) {
851 scsi_requeue_command(q
, cmd
);
854 printk(KERN_INFO
"Device %s not ready.\n",
855 req
->rq_disk
? req
->rq_disk
->disk_name
: "");
856 cmd
= scsi_end_request(cmd
, 0, this_count
, 1);
858 case VOLUME_OVERFLOW
:
859 printk(KERN_INFO
"Volume overflow <%d %d %d %d> CDB: ",
860 cmd
->device
->host
->host_no
,
861 (int)cmd
->device
->channel
,
862 (int)cmd
->device
->id
, (int)cmd
->device
->lun
);
863 __scsi_print_command(cmd
->data_cmnd
);
864 scsi_print_sense("", cmd
);
865 cmd
= scsi_end_request(cmd
, 0, block_bytes
, 1);
870 } /* driver byte != 0 */
871 if (host_byte(result
) == DID_RESET
) {
873 * Third party bus reset or reset for error
874 * recovery reasons. Just retry the request
875 * and see what happens.
877 scsi_requeue_command(q
, cmd
);
881 printk(KERN_INFO
"SCSI error : <%d %d %d %d> return code "
882 "= 0x%x\n", cmd
->device
->host
->host_no
,
883 cmd
->device
->channel
,
885 cmd
->device
->lun
, result
);
887 if (driver_byte(result
) & DRIVER_SENSE
)
888 scsi_print_sense("", cmd
);
890 * Mark a single buffer as not uptodate. Queue the remainder.
891 * We sometimes get this cruft in the event that a medium error
892 * isn't properly reported.
894 block_bytes
= req
->hard_cur_sectors
<< 9;
896 block_bytes
= req
->data_len
;
897 cmd
= scsi_end_request(cmd
, 0, block_bytes
, 1);
900 EXPORT_SYMBOL(scsi_io_completion
);
903 * Function: scsi_init_io()
905 * Purpose: SCSI I/O initialize function.
907 * Arguments: cmd - Command descriptor we wish to initialize
909 * Returns: 0 on success
910 * BLKPREP_DEFER if the failure is retryable
911 * BLKPREP_KILL if the failure is fatal
913 static int scsi_init_io(struct scsi_cmnd
*cmd
)
915 struct request
*req
= cmd
->request
;
916 struct scatterlist
*sgpnt
;
920 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
922 if ((req
->flags
& REQ_BLOCK_PC
) && !req
->bio
) {
923 cmd
->request_bufflen
= req
->data_len
;
924 cmd
->request_buffer
= req
->data
;
925 req
->buffer
= req
->data
;
931 * we used to not use scatter-gather for single segment request,
932 * but now we do (it makes highmem I/O easier to support without
935 cmd
->use_sg
= req
->nr_phys_segments
;
938 * if sg table allocation fails, requeue request later.
940 sgpnt
= scsi_alloc_sgtable(cmd
, GFP_ATOMIC
);
941 if (unlikely(!sgpnt
))
942 return BLKPREP_DEFER
;
944 cmd
->request_buffer
= (char *) sgpnt
;
945 cmd
->request_bufflen
= req
->nr_sectors
<< 9;
946 if (blk_pc_request(req
))
947 cmd
->request_bufflen
= req
->data_len
;
951 * Next, walk the list, and fill in the addresses and sizes of
954 count
= blk_rq_map_sg(req
->q
, req
, cmd
->request_buffer
);
957 * mapped well, send it off
959 if (likely(count
<= cmd
->use_sg
)) {
964 printk(KERN_ERR
"Incorrect number of segments after building list\n");
965 printk(KERN_ERR
"counted %d, received %d\n", count
, cmd
->use_sg
);
966 printk(KERN_ERR
"req nr_sec %lu, cur_nr_sec %u\n", req
->nr_sectors
,
967 req
->current_nr_sectors
);
969 /* release the command and kill it */
970 scsi_release_buffers(cmd
);
971 scsi_put_command(cmd
);
975 static int scsi_prepare_flush_fn(request_queue_t
*q
, struct request
*rq
)
977 struct scsi_device
*sdev
= q
->queuedata
;
978 struct scsi_driver
*drv
;
980 if (sdev
->sdev_state
== SDEV_RUNNING
) {
981 drv
= *(struct scsi_driver
**) rq
->rq_disk
->private_data
;
983 if (drv
->prepare_flush
)
984 return drv
->prepare_flush(q
, rq
);
990 static void scsi_end_flush_fn(request_queue_t
*q
, struct request
*rq
)
992 struct scsi_device
*sdev
= q
->queuedata
;
993 struct request
*flush_rq
= rq
->end_io_data
;
994 struct scsi_driver
*drv
;
996 if (flush_rq
->errors
) {
997 printk("scsi: barrier error, disabling flush support\n");
998 blk_queue_ordered(q
, QUEUE_ORDERED_NONE
);
1001 if (sdev
->sdev_state
== SDEV_RUNNING
) {
1002 drv
= *(struct scsi_driver
**) rq
->rq_disk
->private_data
;
1003 drv
->end_flush(q
, rq
);
1007 static int scsi_issue_flush_fn(request_queue_t
*q
, struct gendisk
*disk
,
1008 sector_t
*error_sector
)
1010 struct scsi_device
*sdev
= q
->queuedata
;
1011 struct scsi_driver
*drv
;
1013 if (sdev
->sdev_state
!= SDEV_RUNNING
)
1016 drv
= *(struct scsi_driver
**) disk
->private_data
;
1017 if (drv
->issue_flush
)
1018 return drv
->issue_flush(&sdev
->sdev_gendev
, error_sector
);
1023 static int scsi_prep_fn(struct request_queue
*q
, struct request
*req
)
1025 struct scsi_device
*sdev
= q
->queuedata
;
1026 struct scsi_cmnd
*cmd
;
1027 int specials_only
= 0;
1030 * Just check to see if the device is online. If it isn't, we
1031 * refuse to process any commands. The device must be brought
1032 * online before trying any recovery commands
1034 if (unlikely(!scsi_device_online(sdev
))) {
1035 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to offline device\n",
1036 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1037 return BLKPREP_KILL
;
1039 if (unlikely(sdev
->sdev_state
!= SDEV_RUNNING
)) {
1040 /* OK, we're not in a running state don't prep
1042 if (sdev
->sdev_state
== SDEV_DEL
) {
1043 /* Device is fully deleted, no commands
1044 * at all allowed down */
1045 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to dead device\n",
1046 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1047 return BLKPREP_KILL
;
1049 /* OK, we only allow special commands (i.e. not
1050 * user initiated ones */
1051 specials_only
= sdev
->sdev_state
;
1055 * Find the actual device driver associated with this command.
1056 * The SPECIAL requests are things like character device or
1057 * ioctls, which did not originate from ll_rw_blk. Note that
1058 * the special field is also used to indicate the cmd for
1059 * the remainder of a partially fulfilled request that can
1060 * come up when there is a medium error. We have to treat
1061 * these two cases differently. We differentiate by looking
1062 * at request->cmd, as this tells us the real story.
1064 if (req
->flags
& REQ_SPECIAL
) {
1065 struct scsi_request
*sreq
= req
->special
;
1067 if (sreq
->sr_magic
== SCSI_REQ_MAGIC
) {
1068 cmd
= scsi_get_command(sreq
->sr_device
, GFP_ATOMIC
);
1071 scsi_init_cmd_from_req(cmd
, sreq
);
1074 } else if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1076 if(unlikely(specials_only
)) {
1077 if(specials_only
== SDEV_QUIESCE
||
1078 specials_only
== SDEV_BLOCK
)
1079 return BLKPREP_DEFER
;
1081 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to device being removed\n",
1082 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1083 return BLKPREP_KILL
;
1088 * Now try and find a command block that we can use.
1090 if (!req
->special
) {
1091 cmd
= scsi_get_command(sdev
, GFP_ATOMIC
);
1097 /* pull a tag out of the request if we have one */
1098 cmd
->tag
= req
->tag
;
1100 blk_dump_rq_flags(req
, "SCSI bad req");
1101 return BLKPREP_KILL
;
1104 /* note the overloading of req->special. When the tag
1105 * is active it always means cmd. If the tag goes
1106 * back for re-queueing, it may be reset */
1111 * FIXME: drop the lock here because the functions below
1112 * expect to be called without the queue lock held. Also,
1113 * previously, we dequeued the request before dropping the
1114 * lock. We hope REQ_STARTED prevents anything untoward from
1117 if (req
->flags
& (REQ_CMD
| REQ_BLOCK_PC
)) {
1118 struct scsi_driver
*drv
;
1122 * This will do a couple of things:
1123 * 1) Fill in the actual SCSI command.
1124 * 2) Fill in any other upper-level specific fields
1127 * If this returns 0, it means that the request failed
1128 * (reading past end of disk, reading offline device,
1129 * etc). This won't actually talk to the device, but
1130 * some kinds of consistency checking may cause the
1131 * request to be rejected immediately.
1135 * This sets up the scatter-gather table (allocating if
1138 ret
= scsi_init_io(cmd
);
1139 if (ret
) /* BLKPREP_KILL return also releases the command */
1143 * Initialize the actual SCSI command for this request.
1145 drv
= *(struct scsi_driver
**)req
->rq_disk
->private_data
;
1146 if (unlikely(!drv
->init_command(cmd
))) {
1147 scsi_release_buffers(cmd
);
1148 scsi_put_command(cmd
);
1149 return BLKPREP_KILL
;
1154 * The request is now prepped, no need to come back here
1156 req
->flags
|= REQ_DONTPREP
;
1160 /* If we defer, the elv_next_request() returns NULL, but the
1161 * queue must be restarted, so we plug here if no returning
1162 * command will automatically do that. */
1163 if (sdev
->device_busy
== 0)
1165 return BLKPREP_DEFER
;
1169 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1172 * Called with the queue_lock held.
1174 static inline int scsi_dev_queue_ready(struct request_queue
*q
,
1175 struct scsi_device
*sdev
)
1177 if (sdev
->device_busy
>= sdev
->queue_depth
)
1179 if (sdev
->device_busy
== 0 && sdev
->device_blocked
) {
1181 * unblock after device_blocked iterates to zero
1183 if (--sdev
->device_blocked
== 0) {
1185 printk("scsi%d (%d:%d) unblocking device at"
1186 " zero depth\n", sdev
->host
->host_no
,
1187 sdev
->id
, sdev
->lun
));
1193 if (sdev
->device_blocked
)
1200 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1201 * return 0. We must end up running the queue again whenever 0 is
1202 * returned, else IO can hang.
1204 * Called with host_lock held.
1206 static inline int scsi_host_queue_ready(struct request_queue
*q
,
1207 struct Scsi_Host
*shost
,
1208 struct scsi_device
*sdev
)
1210 if (shost
->shost_state
== SHOST_RECOVERY
)
1212 if (shost
->host_busy
== 0 && shost
->host_blocked
) {
1214 * unblock after host_blocked iterates to zero
1216 if (--shost
->host_blocked
== 0) {
1218 printk("scsi%d unblocking host at zero depth\n",
1225 if ((shost
->can_queue
> 0 && shost
->host_busy
>= shost
->can_queue
) ||
1226 shost
->host_blocked
|| shost
->host_self_blocked
) {
1227 if (list_empty(&sdev
->starved_entry
))
1228 list_add_tail(&sdev
->starved_entry
, &shost
->starved_list
);
1232 /* We're OK to process the command, so we can't be starved */
1233 if (!list_empty(&sdev
->starved_entry
))
1234 list_del_init(&sdev
->starved_entry
);
1240 * Kill requests for a dead device
1242 static void scsi_kill_requests(request_queue_t
*q
)
1244 struct request
*req
;
1246 while ((req
= elv_next_request(q
)) != NULL
) {
1247 blkdev_dequeue_request(req
);
1248 req
->flags
|= REQ_QUIET
;
1249 while (end_that_request_first(req
, 0, req
->nr_sectors
))
1251 end_that_request_last(req
);
1256 * Function: scsi_request_fn()
1258 * Purpose: Main strategy routine for SCSI.
1260 * Arguments: q - Pointer to actual queue.
1264 * Lock status: IO request lock assumed to be held when called.
1266 static void scsi_request_fn(struct request_queue
*q
)
1268 struct scsi_device
*sdev
= q
->queuedata
;
1269 struct Scsi_Host
*shost
;
1270 struct scsi_cmnd
*cmd
;
1271 struct request
*req
;
1274 printk("scsi: killing requests for dead queue\n");
1275 scsi_kill_requests(q
);
1279 if(!get_device(&sdev
->sdev_gendev
))
1280 /* We must be tearing the block queue down already */
1284 * To start with, we keep looping until the queue is empty, or until
1285 * the host is no longer able to accept any more requests.
1288 while (!blk_queue_plugged(q
)) {
1291 * get next queueable request. We do this early to make sure
1292 * that the request is fully prepared even if we cannot
1295 req
= elv_next_request(q
);
1296 if (!req
|| !scsi_dev_queue_ready(q
, sdev
))
1299 if (unlikely(!scsi_device_online(sdev
))) {
1300 printk(KERN_ERR
"scsi%d (%d:%d): rejecting I/O to offline device\n",
1301 sdev
->host
->host_no
, sdev
->id
, sdev
->lun
);
1302 blkdev_dequeue_request(req
);
1303 req
->flags
|= REQ_QUIET
;
1304 while (end_that_request_first(req
, 0, req
->nr_sectors
))
1306 end_that_request_last(req
);
1312 * Remove the request from the request list.
1314 if (!(blk_queue_tagged(q
) && !blk_queue_start_tag(q
, req
)))
1315 blkdev_dequeue_request(req
);
1316 sdev
->device_busy
++;
1318 spin_unlock(q
->queue_lock
);
1319 spin_lock(shost
->host_lock
);
1321 if (!scsi_host_queue_ready(q
, shost
, sdev
))
1323 if (sdev
->single_lun
) {
1324 if (scsi_target(sdev
)->starget_sdev_user
&&
1325 scsi_target(sdev
)->starget_sdev_user
!= sdev
)
1327 scsi_target(sdev
)->starget_sdev_user
= sdev
;
1332 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1333 * take the lock again.
1335 spin_unlock_irq(shost
->host_lock
);
1338 if (unlikely(cmd
== NULL
)) {
1339 printk(KERN_CRIT
"impossible request in %s.\n"
1340 "please mail a stack trace to "
1341 "linux-scsi@vger.kernel.org",
1347 * Finally, initialize any error handling parameters, and set up
1348 * the timers for timeouts.
1350 scsi_init_cmd_errh(cmd
);
1353 * Dispatch the command to the low-level driver.
1355 rtn
= scsi_dispatch_cmd(cmd
);
1356 spin_lock_irq(q
->queue_lock
);
1358 /* we're refusing the command; because of
1359 * the way locks get dropped, we need to
1360 * check here if plugging is required */
1361 if(sdev
->device_busy
== 0)
1371 spin_unlock_irq(shost
->host_lock
);
1374 * lock q, handle tag, requeue req, and decrement device_busy. We
1375 * must return with queue_lock held.
1377 * Decrementing device_busy without checking it is OK, as all such
1378 * cases (host limits or settings) should run the queue at some
1381 spin_lock_irq(q
->queue_lock
);
1382 blk_requeue_request(q
, req
);
1383 sdev
->device_busy
--;
1384 if(sdev
->device_busy
== 0)
1387 /* must be careful here...if we trigger the ->remove() function
1388 * we cannot be holding the q lock */
1389 spin_unlock_irq(q
->queue_lock
);
1390 put_device(&sdev
->sdev_gendev
);
1391 spin_lock_irq(q
->queue_lock
);
1394 u64
scsi_calculate_bounce_limit(struct Scsi_Host
*shost
)
1396 struct device
*host_dev
;
1397 u64 bounce_limit
= 0xffffffff;
1399 if (shost
->unchecked_isa_dma
)
1400 return BLK_BOUNCE_ISA
;
1402 * Platforms with virtual-DMA translation
1403 * hardware have no practical limit.
1405 if (!PCI_DMA_BUS_IS_PHYS
)
1406 return BLK_BOUNCE_ANY
;
1408 host_dev
= scsi_get_device(shost
);
1409 if (host_dev
&& host_dev
->dma_mask
)
1410 bounce_limit
= *host_dev
->dma_mask
;
1412 return bounce_limit
;
1414 EXPORT_SYMBOL(scsi_calculate_bounce_limit
);
1416 struct request_queue
*scsi_alloc_queue(struct scsi_device
*sdev
)
1418 struct Scsi_Host
*shost
= sdev
->host
;
1419 struct request_queue
*q
;
1421 q
= blk_init_queue(scsi_request_fn
, NULL
);
1425 blk_queue_prep_rq(q
, scsi_prep_fn
);
1427 blk_queue_max_hw_segments(q
, shost
->sg_tablesize
);
1428 blk_queue_max_phys_segments(q
, SCSI_MAX_PHYS_SEGMENTS
);
1429 blk_queue_max_sectors(q
, shost
->max_sectors
);
1430 blk_queue_bounce_limit(q
, scsi_calculate_bounce_limit(shost
));
1431 blk_queue_segment_boundary(q
, shost
->dma_boundary
);
1432 blk_queue_issue_flush_fn(q
, scsi_issue_flush_fn
);
1435 * ordered tags are superior to flush ordering
1437 if (shost
->ordered_tag
)
1438 blk_queue_ordered(q
, QUEUE_ORDERED_TAG
);
1439 else if (shost
->ordered_flush
) {
1440 blk_queue_ordered(q
, QUEUE_ORDERED_FLUSH
);
1441 q
->prepare_flush_fn
= scsi_prepare_flush_fn
;
1442 q
->end_flush_fn
= scsi_end_flush_fn
;
1445 if (!shost
->use_clustering
)
1446 clear_bit(QUEUE_FLAG_CLUSTER
, &q
->queue_flags
);
1450 void scsi_free_queue(struct request_queue
*q
)
1452 blk_cleanup_queue(q
);
1456 * Function: scsi_block_requests()
1458 * Purpose: Utility function used by low-level drivers to prevent further
1459 * commands from being queued to the device.
1461 * Arguments: shost - Host in question
1465 * Lock status: No locks are assumed held.
1467 * Notes: There is no timer nor any other means by which the requests
1468 * get unblocked other than the low-level driver calling
1469 * scsi_unblock_requests().
1471 void scsi_block_requests(struct Scsi_Host
*shost
)
1473 shost
->host_self_blocked
= 1;
1475 EXPORT_SYMBOL(scsi_block_requests
);
1478 * Function: scsi_unblock_requests()
1480 * Purpose: Utility function used by low-level drivers to allow further
1481 * commands from being queued to the device.
1483 * Arguments: shost - Host in question
1487 * Lock status: No locks are assumed held.
1489 * Notes: There is no timer nor any other means by which the requests
1490 * get unblocked other than the low-level driver calling
1491 * scsi_unblock_requests().
1493 * This is done as an API function so that changes to the
1494 * internals of the scsi mid-layer won't require wholesale
1495 * changes to drivers that use this feature.
1497 void scsi_unblock_requests(struct Scsi_Host
*shost
)
1499 shost
->host_self_blocked
= 0;
1500 scsi_run_host_queues(shost
);
1502 EXPORT_SYMBOL(scsi_unblock_requests
);
1504 int __init
scsi_init_queue(void)
1508 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1509 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1510 int size
= sgp
->size
* sizeof(struct scatterlist
);
1512 sgp
->slab
= kmem_cache_create(sgp
->name
, size
, 0,
1513 SLAB_HWCACHE_ALIGN
, NULL
, NULL
);
1515 printk(KERN_ERR
"SCSI: can't init sg slab %s\n",
1519 sgp
->pool
= mempool_create(SG_MEMPOOL_SIZE
,
1520 mempool_alloc_slab
, mempool_free_slab
,
1523 printk(KERN_ERR
"SCSI: can't init sg mempool %s\n",
1531 void scsi_exit_queue(void)
1535 for (i
= 0; i
< SG_MEMPOOL_NR
; i
++) {
1536 struct scsi_host_sg_pool
*sgp
= scsi_sg_pools
+ i
;
1537 mempool_destroy(sgp
->pool
);
1538 kmem_cache_destroy(sgp
->slab
);
1542 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1543 * six bytes if necessary.
1544 * @sreq: SCSI request to fill in with the MODE_SENSE
1545 * @dbd: set if mode sense will allow block descriptors to be returned
1546 * @modepage: mode page being requested
1547 * @buffer: request buffer (may not be smaller than eight bytes)
1548 * @len: length of request buffer.
1549 * @timeout: command timeout
1550 * @retries: number of retries before failing
1551 * @data: returns a structure abstracting the mode header data
1553 * Returns zero if unsuccessful, or the header offset (either 4
1554 * or 8 depending on whether a six or ten byte command was
1555 * issued) if successful.
1558 __scsi_mode_sense(struct scsi_request
*sreq
, int dbd
, int modepage
,
1559 unsigned char *buffer
, int len
, int timeout
, int retries
,
1560 struct scsi_mode_data
*data
) {
1561 unsigned char cmd
[12];
1565 memset(data
, 0, sizeof(*data
));
1566 memset(&cmd
[0], 0, 12);
1567 cmd
[1] = dbd
& 0x18; /* allows DBD and LLBA bits */
1571 use_10_for_ms
= sreq
->sr_device
->use_10_for_ms
;
1573 if (use_10_for_ms
) {
1577 cmd
[0] = MODE_SENSE_10
;
1584 cmd
[0] = MODE_SENSE
;
1589 sreq
->sr_cmd_len
= 0;
1590 memset(sreq
->sr_sense_buffer
, 0, sizeof(sreq
->sr_sense_buffer
));
1591 sreq
->sr_data_direction
= DMA_FROM_DEVICE
;
1593 memset(buffer
, 0, len
);
1595 scsi_wait_req(sreq
, cmd
, buffer
, len
, timeout
, retries
);
1597 /* This code looks awful: what it's doing is making sure an
1598 * ILLEGAL REQUEST sense return identifies the actual command
1599 * byte as the problem. MODE_SENSE commands can return
1600 * ILLEGAL REQUEST if the code page isn't supported */
1602 if (use_10_for_ms
&& !scsi_status_is_good(sreq
->sr_result
) &&
1603 (driver_byte(sreq
->sr_result
) & DRIVER_SENSE
)) {
1604 struct scsi_sense_hdr sshdr
;
1606 if (scsi_request_normalize_sense(sreq
, &sshdr
)) {
1607 if ((sshdr
.sense_key
== ILLEGAL_REQUEST
) &&
1608 (sshdr
.asc
== 0x20) && (sshdr
.ascq
== 0)) {
1610 * Invalid command operation code
1612 sreq
->sr_device
->use_10_for_ms
= 0;
1618 if(scsi_status_is_good(sreq
->sr_result
)) {
1619 data
->header_length
= header_length
;
1621 data
->length
= buffer
[0]*256 + buffer
[1] + 2;
1622 data
->medium_type
= buffer
[2];
1623 data
->device_specific
= buffer
[3];
1624 data
->longlba
= buffer
[4] & 0x01;
1625 data
->block_descriptor_length
= buffer
[6]*256
1628 data
->length
= buffer
[0] + 1;
1629 data
->medium_type
= buffer
[1];
1630 data
->device_specific
= buffer
[2];
1631 data
->block_descriptor_length
= buffer
[3];
1635 return sreq
->sr_result
;
1637 EXPORT_SYMBOL(__scsi_mode_sense
);
1640 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1641 * six bytes if necessary.
1642 * @sdev: scsi device to send command to.
1643 * @dbd: set if mode sense will disable block descriptors in the return
1644 * @modepage: mode page being requested
1645 * @buffer: request buffer (may not be smaller than eight bytes)
1646 * @len: length of request buffer.
1647 * @timeout: command timeout
1648 * @retries: number of retries before failing
1650 * Returns zero if unsuccessful, or the header offset (either 4
1651 * or 8 depending on whether a six or ten byte command was
1652 * issued) if successful.
1655 scsi_mode_sense(struct scsi_device
*sdev
, int dbd
, int modepage
,
1656 unsigned char *buffer
, int len
, int timeout
, int retries
,
1657 struct scsi_mode_data
*data
)
1659 struct scsi_request
*sreq
= scsi_allocate_request(sdev
, GFP_KERNEL
);
1665 ret
= __scsi_mode_sense(sreq
, dbd
, modepage
, buffer
, len
,
1666 timeout
, retries
, data
);
1668 scsi_release_request(sreq
);
1672 EXPORT_SYMBOL(scsi_mode_sense
);
1675 scsi_test_unit_ready(struct scsi_device
*sdev
, int timeout
, int retries
)
1677 struct scsi_request
*sreq
;
1679 TEST_UNIT_READY
, 0, 0, 0, 0, 0,
1683 sreq
= scsi_allocate_request(sdev
, GFP_KERNEL
);
1687 sreq
->sr_data_direction
= DMA_NONE
;
1688 scsi_wait_req(sreq
, cmd
, NULL
, 0, timeout
, retries
);
1690 if ((driver_byte(sreq
->sr_result
) & DRIVER_SENSE
) && sdev
->removable
) {
1691 struct scsi_sense_hdr sshdr
;
1693 if ((scsi_request_normalize_sense(sreq
, &sshdr
)) &&
1694 ((sshdr
.sense_key
== UNIT_ATTENTION
) ||
1695 (sshdr
.sense_key
== NOT_READY
))) {
1697 sreq
->sr_result
= 0;
1700 result
= sreq
->sr_result
;
1701 scsi_release_request(sreq
);
1704 EXPORT_SYMBOL(scsi_test_unit_ready
);
1707 * scsi_device_set_state - Take the given device through the device
1709 * @sdev: scsi device to change the state of.
1710 * @state: state to change to.
1712 * Returns zero if unsuccessful or an error if the requested
1713 * transition is illegal.
1716 scsi_device_set_state(struct scsi_device
*sdev
, enum scsi_device_state state
)
1718 enum scsi_device_state oldstate
= sdev
->sdev_state
;
1720 if (state
== oldstate
)
1725 /* There are no legal states that come back to
1726 * created. This is the manually initialised start
1796 sdev
->sdev_state
= state
;
1800 SCSI_LOG_ERROR_RECOVERY(1,
1801 dev_printk(KERN_ERR
, &sdev
->sdev_gendev
,
1802 "Illegal state transition %s->%s\n",
1803 scsi_device_state_name(oldstate
),
1804 scsi_device_state_name(state
))
1808 EXPORT_SYMBOL(scsi_device_set_state
);
1811 * scsi_device_quiesce - Block user issued commands.
1812 * @sdev: scsi device to quiesce.
1814 * This works by trying to transition to the SDEV_QUIESCE state
1815 * (which must be a legal transition). When the device is in this
1816 * state, only special requests will be accepted, all others will
1817 * be deferred. Since special requests may also be requeued requests,
1818 * a successful return doesn't guarantee the device will be
1819 * totally quiescent.
1821 * Must be called with user context, may sleep.
1823 * Returns zero if unsuccessful or an error if not.
1826 scsi_device_quiesce(struct scsi_device
*sdev
)
1828 int err
= scsi_device_set_state(sdev
, SDEV_QUIESCE
);
1832 scsi_run_queue(sdev
->request_queue
);
1833 while (sdev
->device_busy
) {
1834 msleep_interruptible(200);
1835 scsi_run_queue(sdev
->request_queue
);
1839 EXPORT_SYMBOL(scsi_device_quiesce
);
1842 * scsi_device_resume - Restart user issued commands to a quiesced device.
1843 * @sdev: scsi device to resume.
1845 * Moves the device from quiesced back to running and restarts the
1848 * Must be called with user context, may sleep.
1851 scsi_device_resume(struct scsi_device
*sdev
)
1853 if(scsi_device_set_state(sdev
, SDEV_RUNNING
))
1855 scsi_run_queue(sdev
->request_queue
);
1857 EXPORT_SYMBOL(scsi_device_resume
);
1860 device_quiesce_fn(struct scsi_device
*sdev
, void *data
)
1862 scsi_device_quiesce(sdev
);
1866 scsi_target_quiesce(struct scsi_target
*starget
)
1868 starget_for_each_device(starget
, NULL
, device_quiesce_fn
);
1870 EXPORT_SYMBOL(scsi_target_quiesce
);
1873 device_resume_fn(struct scsi_device
*sdev
, void *data
)
1875 scsi_device_resume(sdev
);
1879 scsi_target_resume(struct scsi_target
*starget
)
1881 starget_for_each_device(starget
, NULL
, device_resume_fn
);
1883 EXPORT_SYMBOL(scsi_target_resume
);
1886 * scsi_internal_device_block - internal function to put a device
1887 * temporarily into the SDEV_BLOCK state
1888 * @sdev: device to block
1890 * Block request made by scsi lld's to temporarily stop all
1891 * scsi commands on the specified device. Called from interrupt
1892 * or normal process context.
1894 * Returns zero if successful or error if not
1897 * This routine transitions the device to the SDEV_BLOCK state
1898 * (which must be a legal transition). When the device is in this
1899 * state, all commands are deferred until the scsi lld reenables
1900 * the device with scsi_device_unblock or device_block_tmo fires.
1901 * This routine assumes the host_lock is held on entry.
1904 scsi_internal_device_block(struct scsi_device
*sdev
)
1906 request_queue_t
*q
= sdev
->request_queue
;
1907 unsigned long flags
;
1910 err
= scsi_device_set_state(sdev
, SDEV_BLOCK
);
1915 * The device has transitioned to SDEV_BLOCK. Stop the
1916 * block layer from calling the midlayer with this device's
1919 spin_lock_irqsave(q
->queue_lock
, flags
);
1921 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1925 EXPORT_SYMBOL_GPL(scsi_internal_device_block
);
1928 * scsi_internal_device_unblock - resume a device after a block request
1929 * @sdev: device to resume
1931 * Called by scsi lld's or the midlayer to restart the device queue
1932 * for the previously suspended scsi device. Called from interrupt or
1933 * normal process context.
1935 * Returns zero if successful or error if not.
1938 * This routine transitions the device to the SDEV_RUNNING state
1939 * (which must be a legal transition) allowing the midlayer to
1940 * goose the queue for this device. This routine assumes the
1941 * host_lock is held upon entry.
1944 scsi_internal_device_unblock(struct scsi_device
*sdev
)
1946 request_queue_t
*q
= sdev
->request_queue
;
1948 unsigned long flags
;
1951 * Try to transition the scsi device to SDEV_RUNNING
1952 * and goose the device queue if successful.
1954 err
= scsi_device_set_state(sdev
, SDEV_RUNNING
);
1958 spin_lock_irqsave(q
->queue_lock
, flags
);
1960 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1964 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock
);
1967 device_block(struct scsi_device
*sdev
, void *data
)
1969 scsi_internal_device_block(sdev
);
1973 target_block(struct device
*dev
, void *data
)
1975 if (scsi_is_target_device(dev
))
1976 starget_for_each_device(to_scsi_target(dev
), NULL
,
1982 scsi_target_block(struct device
*dev
)
1984 if (scsi_is_target_device(dev
))
1985 starget_for_each_device(to_scsi_target(dev
), NULL
,
1988 device_for_each_child(dev
, NULL
, target_block
);
1990 EXPORT_SYMBOL_GPL(scsi_target_block
);
1993 device_unblock(struct scsi_device
*sdev
, void *data
)
1995 scsi_internal_device_unblock(sdev
);
1999 target_unblock(struct device
*dev
, void *data
)
2001 if (scsi_is_target_device(dev
))
2002 starget_for_each_device(to_scsi_target(dev
), NULL
,
2008 scsi_target_unblock(struct device
*dev
)
2010 if (scsi_is_target_device(dev
))
2011 starget_for_each_device(to_scsi_target(dev
), NULL
,
2014 device_for_each_child(dev
, NULL
, target_unblock
);
2016 EXPORT_SYMBOL_GPL(scsi_target_unblock
);