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 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,
100 * Function: scsi_queue_insert()
102 * Purpose: Insert a command in the midlevel queue.
104 * Arguments: cmd - command that we are adding to queue.
105 * reason - why we are inserting command to queue.
107 * Lock status: Assumed that lock is not held upon entry.
111 * Notes: We do this for one of two cases. Either the host is busy
112 * and it cannot accept any more commands for the time being,
113 * or the device returned QUEUE_FULL and can accept no more
115 * Notes: This could be called either from an interrupt context or a
116 * normal process context.
118 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
120 struct Scsi_Host *host = cmd->device->host;
121 struct scsi_device *device = cmd->device;
124 printk("Inserting command %p into mlqueue\n", cmd));
127 * We are inserting the command into the ml queue. First, we
128 * cancel the timer, so it doesn't time out.
130 scsi_delete_timer(cmd);
133 * Next, set the appropriate busy bit for the device/host.
135 * If the host/device isn't busy, assume that something actually
136 * completed, and that we should be able to queue a command now.
138 * Note that the prior mid-layer assumption that any host could
139 * always queue at least one command is now broken. The mid-layer
140 * will implement a user specifiable stall (see
141 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
142 * if a command is requeued with no other commands outstanding
143 * either for the device or for the host.
145 if (reason == SCSI_MLQUEUE_HOST_BUSY)
146 host->host_blocked = host->max_host_blocked;
147 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
148 device->device_blocked = device->max_device_blocked;
151 * Register the fact that we own the thing for now.
153 cmd->state = SCSI_STATE_MLQUEUE;
154 cmd->owner = SCSI_OWNER_MIDLEVEL;
157 * Decrement the counters, since these commands are no longer
158 * active on the host/device.
160 scsi_device_unbusy(device);
163 * Insert this command at the head of the queue for it's device.
164 * It will go before all other commands that are already in the queue.
166 * NOTE: there is magic here about the way the queue is plugged if
167 * we have no outstanding commands.
169 * Although this *doesn't* plug the queue, it does call the request
170 * function. The SCSI request function detects the blocked condition
171 * and plugs the queue appropriately.
173 blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1);
178 * Function: scsi_do_req
180 * Purpose: Queue a SCSI request
182 * Arguments: sreq - command descriptor.
183 * cmnd - actual SCSI command to be performed.
184 * buffer - data buffer.
185 * bufflen - size of data buffer.
186 * done - completion function to be run.
187 * timeout - how long to let it run before timeout.
188 * retries - number of retries we allow.
190 * Lock status: No locks held upon entry.
194 * Notes: This function is only used for queueing requests for things
195 * like ioctls and character device requests - this is because
196 * we essentially just inject a request into the queue for the
199 * In order to support the scsi_device_quiesce function, we
200 * now inject requests on the *head* of the device queue
201 * rather than the tail.
203 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
204 void *buffer, unsigned bufflen,
205 void (*done)(struct scsi_cmnd *),
206 int timeout, int retries)
209 * If the upper level driver is reusing these things, then
210 * we should release the low-level block now. Another one will
211 * be allocated later when this request is getting queued.
213 __scsi_release_request(sreq);
216 * Our own function scsi_done (which marks the host as not busy,
217 * disables the timeout counter, etc) will be called by us or by the
218 * scsi_hosts[host].queuecommand() function needs to also call
219 * the completion function for the high level driver.
221 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
222 sreq->sr_bufflen = bufflen;
223 sreq->sr_buffer = buffer;
224 sreq->sr_allowed = retries;
225 sreq->sr_done = done;
226 sreq->sr_timeout_per_command = timeout;
228 if (sreq->sr_cmd_len == 0)
229 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
232 * head injection *required* here otherwise quiesce won't work
234 scsi_insert_special_req(sreq, 1);
236 EXPORT_SYMBOL(scsi_do_req);
238 static void scsi_wait_done(struct scsi_cmnd *cmd)
240 struct request *req = cmd->request;
241 struct request_queue *q = cmd->device->request_queue;
244 req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
246 spin_lock_irqsave(q->queue_lock, flags);
247 if (blk_rq_tagged(req))
248 blk_queue_end_tag(q, req);
249 spin_unlock_irqrestore(q->queue_lock, flags);
252 complete(req->waiting);
255 /* This is the end routine we get to if a command was never attached
256 * to the request. Simply complete the request without changing
257 * rq_status; this will cause a DRIVER_ERROR. */
258 static void scsi_wait_req_end_io(struct request *req)
260 BUG_ON(!req->waiting);
262 complete(req->waiting);
265 void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
266 unsigned bufflen, int timeout, int retries)
268 DECLARE_COMPLETION(wait);
270 sreq->sr_request->waiting = &wait;
271 sreq->sr_request->rq_status = RQ_SCSI_BUSY;
272 sreq->sr_request->end_io = scsi_wait_req_end_io;
273 scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
275 wait_for_completion(&wait);
276 sreq->sr_request->waiting = NULL;
277 if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
278 sreq->sr_result |= (DRIVER_ERROR << 24);
280 __scsi_release_request(sreq);
282 EXPORT_SYMBOL(scsi_wait_req);
285 * Function: scsi_init_cmd_errh()
287 * Purpose: Initialize cmd fields related to error handling.
289 * Arguments: cmd - command that is ready to be queued.
293 * Notes: This function has the job of initializing a number of
294 * fields related to error handling. Typically this will
295 * be called once for each command, as required.
297 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
299 cmd->owner = SCSI_OWNER_MIDLEVEL;
300 cmd->serial_number = 0;
301 cmd->serial_number_at_timeout = 0;
302 cmd->abort_reason = 0;
304 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
306 if (cmd->cmd_len == 0)
307 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
310 * We need saved copies of a number of fields - this is because
311 * error handling may need to overwrite these with different values
312 * to run different commands, and once error handling is complete,
313 * we will need to restore these values prior to running the actual
316 cmd->old_use_sg = cmd->use_sg;
317 cmd->old_cmd_len = cmd->cmd_len;
318 cmd->sc_old_data_direction = cmd->sc_data_direction;
319 cmd->old_underflow = cmd->underflow;
320 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
321 cmd->buffer = cmd->request_buffer;
322 cmd->bufflen = cmd->request_bufflen;
323 cmd->abort_reason = 0;
329 * Function: scsi_setup_cmd_retry()
331 * Purpose: Restore the command state for a retry
333 * Arguments: cmd - command to be restored
337 * Notes: Immediately prior to retrying a command, we need
338 * to restore certain fields that we saved above.
340 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
342 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
343 cmd->request_buffer = cmd->buffer;
344 cmd->request_bufflen = cmd->bufflen;
345 cmd->use_sg = cmd->old_use_sg;
346 cmd->cmd_len = cmd->old_cmd_len;
347 cmd->sc_data_direction = cmd->sc_old_data_direction;
348 cmd->underflow = cmd->old_underflow;
351 void scsi_device_unbusy(struct scsi_device *sdev)
353 struct Scsi_Host *shost = sdev->host;
356 spin_lock_irqsave(shost->host_lock, flags);
358 if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
360 scsi_eh_wakeup(shost);
361 spin_unlock(shost->host_lock);
362 spin_lock(&sdev->sdev_lock);
364 spin_unlock_irqrestore(&sdev->sdev_lock, flags);
368 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
369 * and call blk_run_queue for all the scsi_devices on the target -
370 * including current_sdev first.
372 * Called with *no* scsi locks held.
374 static void scsi_single_lun_run(struct scsi_device *current_sdev)
376 struct Scsi_Host *shost = current_sdev->host;
377 struct scsi_device *sdev, *tmp;
378 struct scsi_target *starget = scsi_target(current_sdev);
381 spin_lock_irqsave(shost->host_lock, flags);
382 starget->starget_sdev_user = NULL;
383 spin_unlock_irqrestore(shost->host_lock, flags);
386 * Call blk_run_queue for all LUNs on the target, starting with
387 * current_sdev. We race with others (to set starget_sdev_user),
388 * but in most cases, we will be first. Ideally, each LU on the
389 * target would get some limited time or requests on the target.
391 blk_run_queue(current_sdev->request_queue);
393 spin_lock_irqsave(shost->host_lock, flags);
394 if (starget->starget_sdev_user)
396 list_for_each_entry_safe(sdev, tmp, &starget->devices,
397 same_target_siblings) {
398 if (sdev == current_sdev)
400 if (scsi_device_get(sdev))
403 spin_unlock_irqrestore(shost->host_lock, flags);
404 blk_run_queue(sdev->request_queue);
405 spin_lock_irqsave(shost->host_lock, flags);
407 scsi_device_put(sdev);
410 spin_unlock_irqrestore(shost->host_lock, flags);
414 * Function: scsi_run_queue()
416 * Purpose: Select a proper request queue to serve next
418 * Arguments: q - last request's queue
422 * Notes: The previous command was completely finished, start
423 * a new one if possible.
425 static void scsi_run_queue(struct request_queue *q)
427 struct scsi_device *sdev = q->queuedata;
428 struct Scsi_Host *shost = sdev->host;
431 if (sdev->single_lun)
432 scsi_single_lun_run(sdev);
434 spin_lock_irqsave(shost->host_lock, flags);
435 while (!list_empty(&shost->starved_list) &&
436 !shost->host_blocked && !shost->host_self_blocked &&
437 !((shost->can_queue > 0) &&
438 (shost->host_busy >= shost->can_queue))) {
440 * As long as shost is accepting commands and we have
441 * starved queues, call blk_run_queue. scsi_request_fn
442 * drops the queue_lock and can add us back to the
445 * host_lock protects the starved_list and starved_entry.
446 * scsi_request_fn must get the host_lock before checking
447 * or modifying starved_list or starved_entry.
449 sdev = list_entry(shost->starved_list.next,
450 struct scsi_device, starved_entry);
451 list_del_init(&sdev->starved_entry);
452 spin_unlock_irqrestore(shost->host_lock, flags);
454 blk_run_queue(sdev->request_queue);
456 spin_lock_irqsave(shost->host_lock, flags);
457 if (unlikely(!list_empty(&sdev->starved_entry)))
459 * sdev lost a race, and was put back on the
460 * starved list. This is unlikely but without this
461 * in theory we could loop forever.
465 spin_unlock_irqrestore(shost->host_lock, flags);
471 * Function: scsi_requeue_command()
473 * Purpose: Handle post-processing of completed commands.
475 * Arguments: q - queue to operate on
476 * cmd - command that may need to be requeued.
480 * Notes: After command completion, there may be blocks left
481 * over which weren't finished by the previous command
482 * this can be for a number of reasons - the main one is
483 * I/O errors in the middle of the request, in which case
484 * we need to request the blocks that come after the bad
487 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
489 cmd->request->flags &= ~REQ_DONTPREP;
490 blk_insert_request(q, cmd->request, 1, cmd, 1);
495 void scsi_next_command(struct scsi_cmnd *cmd)
497 struct request_queue *q = cmd->device->request_queue;
499 scsi_put_command(cmd);
503 void scsi_run_host_queues(struct Scsi_Host *shost)
505 struct scsi_device *sdev;
507 shost_for_each_device(sdev, shost)
508 scsi_run_queue(sdev->request_queue);
512 * Function: scsi_end_request()
514 * Purpose: Post-processing of completed commands (usually invoked at end
515 * of upper level post-processing and scsi_io_completion).
517 * Arguments: cmd - command that is complete.
518 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
519 * bytes - number of bytes of completed I/O
520 * requeue - indicates whether we should requeue leftovers.
522 * Lock status: Assumed that lock is not held upon entry.
524 * Returns: cmd if requeue done or required, NULL otherwise
526 * Notes: This is called for block device requests in order to
527 * mark some number of sectors as complete.
529 * We are guaranteeing that the request queue will be goosed
530 * at some point during this call.
532 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
533 int bytes, int requeue)
535 request_queue_t *q = cmd->device->request_queue;
536 struct request *req = cmd->request;
540 * If there are blocks left over at the end, set up the command
541 * to queue the remainder of them.
543 if (end_that_request_chunk(req, uptodate, bytes)) {
544 int leftover = (req->hard_nr_sectors << 9);
546 if (blk_pc_request(req))
547 leftover = req->data_len;
549 /* kill remainder if no retrys */
550 if (!uptodate && blk_noretry_request(req))
551 end_that_request_chunk(req, 0, leftover);
555 * Bleah. Leftovers again. Stick the
556 * leftovers in the front of the
557 * queue, and goose the queue again.
559 scsi_requeue_command(q, cmd);
565 add_disk_randomness(req->rq_disk);
567 spin_lock_irqsave(q->queue_lock, flags);
568 if (blk_rq_tagged(req))
569 blk_queue_end_tag(q, req);
570 end_that_request_last(req);
571 spin_unlock_irqrestore(q->queue_lock, flags);
574 * This will goose the queue request function at the end, so we don't
575 * need to worry about launching another command.
577 scsi_next_command(cmd);
581 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
583 struct scsi_host_sg_pool *sgp;
584 struct scatterlist *sgl;
586 BUG_ON(!cmd->use_sg);
588 switch (cmd->use_sg) {
598 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
602 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
606 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
617 sgp = scsi_sg_pools + cmd->sglist_len;
618 sgl = mempool_alloc(sgp->pool, gfp_mask);
620 memset(sgl, 0, sgp->size);
624 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
626 struct scsi_host_sg_pool *sgp;
628 BUG_ON(index > SG_MEMPOOL_NR);
630 sgp = scsi_sg_pools + index;
631 mempool_free(sgl, sgp->pool);
635 * Function: scsi_release_buffers()
637 * Purpose: Completion processing for block device I/O requests.
639 * Arguments: cmd - command that we are bailing.
641 * Lock status: Assumed that no lock is held upon entry.
645 * Notes: In the event that an upper level driver rejects a
646 * command, we must release resources allocated during
647 * the __init_io() function. Primarily this would involve
648 * the scatter-gather table, and potentially any bounce
651 static void scsi_release_buffers(struct scsi_cmnd *cmd)
653 struct request *req = cmd->request;
656 * Free up any indirection buffers we allocated for DMA purposes.
659 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
660 else if (cmd->request_buffer != req->buffer)
661 kfree(cmd->request_buffer);
664 * Zero these out. They now point to freed memory, and it is
665 * dangerous to hang onto the pointers.
669 cmd->request_buffer = NULL;
670 cmd->request_bufflen = 0;
674 * Function: scsi_io_completion()
676 * Purpose: Completion processing for block device I/O requests.
678 * Arguments: cmd - command that is finished.
680 * Lock status: Assumed that no lock is held upon entry.
684 * Notes: This function is matched in terms of capabilities to
685 * the function that created the scatter-gather list.
686 * In other words, if there are no bounce buffers
687 * (the normal case for most drivers), we don't need
688 * the logic to deal with cleaning up afterwards.
690 * We must do one of several things here:
692 * a) Call scsi_end_request. This will finish off the
693 * specified number of sectors. If we are done, the
694 * command block will be released, and the queue
695 * function will be goosed. If we are not done, then
696 * scsi_end_request will directly goose the queue.
698 * b) We can just use scsi_requeue_command() here. This would
699 * be used if we just wanted to retry, for example.
701 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
702 unsigned int block_bytes)
704 int result = cmd->result;
705 int this_count = cmd->bufflen;
706 request_queue_t *q = cmd->device->request_queue;
707 struct request *req = cmd->request;
708 int clear_errors = 1;
709 struct scsi_sense_hdr sshdr;
711 int sense_deferred = 0;
713 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
717 * Free up any indirection buffers we allocated for DMA purposes.
718 * For the case of a READ, we need to copy the data out of the
719 * bounce buffer and into the real buffer.
722 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
723 else if (cmd->buffer != req->buffer) {
724 if (rq_data_dir(req) == READ) {
726 char *to = bio_kmap_irq(req->bio, &flags);
727 memcpy(to, cmd->buffer, cmd->bufflen);
728 bio_kunmap_irq(to, &flags);
734 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
736 sense_deferred = scsi_sense_is_deferred(&sshdr);
738 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
739 req->errors = result;
742 if (sense_valid && req->sense) {
744 * SG_IO wants current and deferred errors
746 int len = 8 + cmd->sense_buffer[7];
748 if (len > SCSI_SENSE_BUFFERSIZE)
749 len = SCSI_SENSE_BUFFERSIZE;
750 memcpy(req->sense, cmd->sense_buffer, len);
751 req->sense_len = len;
754 req->data_len = cmd->resid;
758 * Zero these out. They now point to freed memory, and it is
759 * dangerous to hang onto the pointers.
763 cmd->request_buffer = NULL;
764 cmd->request_bufflen = 0;
767 * Next deal with any sectors which we were able to correctly
770 if (good_bytes >= 0) {
771 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
772 req->nr_sectors, good_bytes));
773 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
778 * If multiple sectors are requested in one buffer, then
779 * they will have been finished off by the first command.
780 * If not, then we have a multi-buffer command.
782 * If block_bytes != 0, it means we had a medium error
783 * of some sort, and that we want to mark some number of
784 * sectors as not uptodate. Thus we want to inhibit
785 * requeueing right here - we will requeue down below
786 * when we handle the bad sectors.
788 cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
791 * If the command completed without error, then either finish off the
792 * rest of the command, or start a new one.
794 if (result == 0 || cmd == NULL ) {
799 * Now, if we were good little boys and girls, Santa left us a request
800 * sense buffer. We can extract information from this, so we
801 * can choose a block to remap, etc.
803 if (sense_valid && !sense_deferred) {
804 switch (sshdr.sense_key) {
806 if (cmd->device->removable) {
807 /* detected disc change. set a bit
808 * and quietly refuse further access.
810 cmd->device->changed = 1;
811 cmd = scsi_end_request(cmd, 0,
816 * Must have been a power glitch, or a
817 * bus reset. Could not have been a
818 * media change, so we just retry the
819 * request and see what happens.
821 scsi_requeue_command(q, cmd);
825 case ILLEGAL_REQUEST:
827 * If we had an ILLEGAL REQUEST returned, then we may
828 * have performed an unsupported command. The only
829 * thing this should be would be a ten byte read where
830 * only a six byte read was supported. Also, on a
831 * system where READ CAPACITY failed, we may have read
832 * past the end of the disk.
834 if (cmd->device->use_10_for_rw &&
835 (cmd->cmnd[0] == READ_10 ||
836 cmd->cmnd[0] == WRITE_10)) {
837 cmd->device->use_10_for_rw = 0;
839 * This will cause a retry with a 6-byte
842 scsi_requeue_command(q, cmd);
845 cmd = scsi_end_request(cmd, 0, this_count, 1);
851 * If the device is in the process of becoming ready,
854 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
855 scsi_requeue_command(q, cmd);
858 printk(KERN_INFO "Device %s not ready.\n",
859 req->rq_disk ? req->rq_disk->disk_name : "");
860 cmd = scsi_end_request(cmd, 0, this_count, 1);
862 case VOLUME_OVERFLOW:
863 printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
864 cmd->device->host->host_no,
865 (int)cmd->device->channel,
866 (int)cmd->device->id, (int)cmd->device->lun);
867 __scsi_print_command(cmd->data_cmnd);
868 scsi_print_sense("", cmd);
869 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
874 } /* driver byte != 0 */
875 if (host_byte(result) == DID_RESET) {
877 * Third party bus reset or reset for error
878 * recovery reasons. Just retry the request
879 * and see what happens.
881 scsi_requeue_command(q, cmd);
885 printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
886 "= 0x%x\n", cmd->device->host->host_no,
887 cmd->device->channel,
889 cmd->device->lun, result);
891 if (driver_byte(result) & DRIVER_SENSE)
892 scsi_print_sense("", cmd);
894 * Mark a single buffer as not uptodate. Queue the remainder.
895 * We sometimes get this cruft in the event that a medium error
896 * isn't properly reported.
898 block_bytes = req->hard_cur_sectors << 9;
900 block_bytes = req->data_len;
901 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
904 EXPORT_SYMBOL(scsi_io_completion);
907 * Function: scsi_init_io()
909 * Purpose: SCSI I/O initialize function.
911 * Arguments: cmd - Command descriptor we wish to initialize
913 * Returns: 0 on success
914 * BLKPREP_DEFER if the failure is retryable
915 * BLKPREP_KILL if the failure is fatal
917 static int scsi_init_io(struct scsi_cmnd *cmd)
919 struct request *req = cmd->request;
920 struct scatterlist *sgpnt;
924 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
926 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
927 cmd->request_bufflen = req->data_len;
928 cmd->request_buffer = req->data;
929 req->buffer = req->data;
935 * we used to not use scatter-gather for single segment request,
936 * but now we do (it makes highmem I/O easier to support without
939 cmd->use_sg = req->nr_phys_segments;
942 * if sg table allocation fails, requeue request later.
944 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
945 if (unlikely(!sgpnt)) {
946 req->flags |= REQ_SPECIAL;
947 return BLKPREP_DEFER;
950 cmd->request_buffer = (char *) sgpnt;
951 cmd->request_bufflen = req->nr_sectors << 9;
952 if (blk_pc_request(req))
953 cmd->request_bufflen = req->data_len;
957 * Next, walk the list, and fill in the addresses and sizes of
960 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
963 * mapped well, send it off
965 if (likely(count <= cmd->use_sg)) {
970 printk(KERN_ERR "Incorrect number of segments after building list\n");
971 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
972 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
973 req->current_nr_sectors);
975 /* release the command and kill it */
976 scsi_release_buffers(cmd);
977 scsi_put_command(cmd);
981 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
983 struct scsi_device *sdev = q->queuedata;
984 struct scsi_driver *drv;
986 if (sdev->sdev_state == SDEV_RUNNING) {
987 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
989 if (drv->prepare_flush)
990 return drv->prepare_flush(q, rq);
996 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
998 struct scsi_device *sdev = q->queuedata;
999 struct request *flush_rq = rq->end_io_data;
1000 struct scsi_driver *drv;
1002 if (flush_rq->errors) {
1003 printk("scsi: barrier error, disabling flush support\n");
1004 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1007 if (sdev->sdev_state == SDEV_RUNNING) {
1008 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1009 drv->end_flush(q, rq);
1013 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1014 sector_t *error_sector)
1016 struct scsi_device *sdev = q->queuedata;
1017 struct scsi_driver *drv;
1019 if (sdev->sdev_state != SDEV_RUNNING)
1022 drv = *(struct scsi_driver **) disk->private_data;
1023 if (drv->issue_flush)
1024 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1029 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1031 struct scsi_device *sdev = q->queuedata;
1032 struct scsi_cmnd *cmd;
1033 int specials_only = 0;
1036 * Just check to see if the device is online. If it isn't, we
1037 * refuse to process any commands. The device must be brought
1038 * online before trying any recovery commands
1040 if (unlikely(!scsi_device_online(sdev))) {
1041 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1042 sdev->host->host_no, sdev->id, sdev->lun);
1043 return BLKPREP_KILL;
1045 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1046 /* OK, we're not in a running state don't prep
1048 if (sdev->sdev_state == SDEV_DEL) {
1049 /* Device is fully deleted, no commands
1050 * at all allowed down */
1051 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1052 sdev->host->host_no, sdev->id, sdev->lun);
1053 return BLKPREP_KILL;
1055 /* OK, we only allow special commands (i.e. not
1056 * user initiated ones */
1057 specials_only = sdev->sdev_state;
1061 * Find the actual device driver associated with this command.
1062 * The SPECIAL requests are things like character device or
1063 * ioctls, which did not originate from ll_rw_blk. Note that
1064 * the special field is also used to indicate the cmd for
1065 * the remainder of a partially fulfilled request that can
1066 * come up when there is a medium error. We have to treat
1067 * these two cases differently. We differentiate by looking
1068 * at request->cmd, as this tells us the real story.
1070 if (req->flags & REQ_SPECIAL) {
1071 struct scsi_request *sreq = req->special;
1073 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1074 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1077 scsi_init_cmd_from_req(cmd, sreq);
1080 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1082 if(unlikely(specials_only)) {
1083 if(specials_only == SDEV_QUIESCE ||
1084 specials_only == SDEV_BLOCK)
1085 return BLKPREP_DEFER;
1087 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1088 sdev->host->host_no, sdev->id, sdev->lun);
1089 return BLKPREP_KILL;
1094 * Now try and find a command block that we can use.
1096 if (!req->special) {
1097 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1103 /* pull a tag out of the request if we have one */
1104 cmd->tag = req->tag;
1106 blk_dump_rq_flags(req, "SCSI bad req");
1107 return BLKPREP_KILL;
1110 /* note the overloading of req->special. When the tag
1111 * is active it always means cmd. If the tag goes
1112 * back for re-queueing, it may be reset */
1117 * FIXME: drop the lock here because the functions below
1118 * expect to be called without the queue lock held. Also,
1119 * previously, we dequeued the request before dropping the
1120 * lock. We hope REQ_STARTED prevents anything untoward from
1123 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1124 struct scsi_driver *drv;
1128 * This will do a couple of things:
1129 * 1) Fill in the actual SCSI command.
1130 * 2) Fill in any other upper-level specific fields
1133 * If this returns 0, it means that the request failed
1134 * (reading past end of disk, reading offline device,
1135 * etc). This won't actually talk to the device, but
1136 * some kinds of consistency checking may cause the
1137 * request to be rejected immediately.
1141 * This sets up the scatter-gather table (allocating if
1144 ret = scsi_init_io(cmd);
1145 if (ret) /* BLKPREP_KILL return also releases the command */
1149 * Initialize the actual SCSI command for this request.
1151 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1152 if (unlikely(!drv->init_command(cmd))) {
1153 scsi_release_buffers(cmd);
1154 scsi_put_command(cmd);
1155 return BLKPREP_KILL;
1160 * The request is now prepped, no need to come back here
1162 req->flags |= REQ_DONTPREP;
1166 /* If we defer, the elv_next_request() returns NULL, but the
1167 * queue must be restarted, so we plug here if no returning
1168 * command will automatically do that. */
1169 if (sdev->device_busy == 0)
1171 return BLKPREP_DEFER;
1175 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1178 * Called with the queue_lock held.
1180 static inline int scsi_dev_queue_ready(struct request_queue *q,
1181 struct scsi_device *sdev)
1183 if (sdev->device_busy >= sdev->queue_depth)
1185 if (sdev->device_busy == 0 && sdev->device_blocked) {
1187 * unblock after device_blocked iterates to zero
1189 if (--sdev->device_blocked == 0) {
1191 printk("scsi%d (%d:%d) unblocking device at"
1192 " zero depth\n", sdev->host->host_no,
1193 sdev->id, sdev->lun));
1199 if (sdev->device_blocked)
1206 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1207 * return 0. We must end up running the queue again whenever 0 is
1208 * returned, else IO can hang.
1210 * Called with host_lock held.
1212 static inline int scsi_host_queue_ready(struct request_queue *q,
1213 struct Scsi_Host *shost,
1214 struct scsi_device *sdev)
1216 if (test_bit(SHOST_RECOVERY, &shost->shost_state))
1218 if (shost->host_busy == 0 && shost->host_blocked) {
1220 * unblock after host_blocked iterates to zero
1222 if (--shost->host_blocked == 0) {
1224 printk("scsi%d unblocking host at zero depth\n",
1231 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1232 shost->host_blocked || shost->host_self_blocked) {
1233 if (list_empty(&sdev->starved_entry))
1234 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1238 /* We're OK to process the command, so we can't be starved */
1239 if (!list_empty(&sdev->starved_entry))
1240 list_del_init(&sdev->starved_entry);
1246 * Kill requests for a dead device
1248 static void scsi_kill_requests(request_queue_t *q)
1250 struct request *req;
1252 while ((req = elv_next_request(q)) != NULL) {
1253 blkdev_dequeue_request(req);
1254 req->flags |= REQ_QUIET;
1255 while (end_that_request_first(req, 0, req->nr_sectors))
1257 end_that_request_last(req);
1262 * Function: scsi_request_fn()
1264 * Purpose: Main strategy routine for SCSI.
1266 * Arguments: q - Pointer to actual queue.
1270 * Lock status: IO request lock assumed to be held when called.
1272 static void scsi_request_fn(struct request_queue *q)
1274 struct scsi_device *sdev = q->queuedata;
1275 struct Scsi_Host *shost;
1276 struct scsi_cmnd *cmd;
1277 struct request *req;
1280 printk("scsi: killing requests for dead queue\n");
1281 scsi_kill_requests(q);
1285 if(!get_device(&sdev->sdev_gendev))
1286 /* We must be tearing the block queue down already */
1290 * To start with, we keep looping until the queue is empty, or until
1291 * the host is no longer able to accept any more requests.
1294 while (!blk_queue_plugged(q)) {
1297 * get next queueable request. We do this early to make sure
1298 * that the request is fully prepared even if we cannot
1301 req = elv_next_request(q);
1302 if (!req || !scsi_dev_queue_ready(q, sdev))
1305 if (unlikely(!scsi_device_online(sdev))) {
1306 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1307 sdev->host->host_no, sdev->id, sdev->lun);
1308 blkdev_dequeue_request(req);
1309 req->flags |= REQ_QUIET;
1310 while (end_that_request_first(req, 0, req->nr_sectors))
1312 end_that_request_last(req);
1318 * Remove the request from the request list.
1320 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1321 blkdev_dequeue_request(req);
1322 sdev->device_busy++;
1324 spin_unlock(q->queue_lock);
1325 spin_lock(shost->host_lock);
1327 if (!scsi_host_queue_ready(q, shost, sdev))
1329 if (sdev->single_lun) {
1330 if (scsi_target(sdev)->starget_sdev_user &&
1331 scsi_target(sdev)->starget_sdev_user != sdev)
1333 scsi_target(sdev)->starget_sdev_user = sdev;
1338 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1339 * take the lock again.
1341 spin_unlock_irq(shost->host_lock);
1344 if (unlikely(cmd == NULL)) {
1345 printk(KERN_CRIT "impossible request in %s.\n"
1346 "please mail a stack trace to "
1347 "linux-scsi@vger.kernel.org",
1353 * Finally, initialize any error handling parameters, and set up
1354 * the timers for timeouts.
1356 scsi_init_cmd_errh(cmd);
1359 * Dispatch the command to the low-level driver.
1361 rtn = scsi_dispatch_cmd(cmd);
1362 spin_lock_irq(q->queue_lock);
1364 /* we're refusing the command; because of
1365 * the way locks get dropped, we need to
1366 * check here if plugging is required */
1367 if(sdev->device_busy == 0)
1377 spin_unlock_irq(shost->host_lock);
1380 * lock q, handle tag, requeue req, and decrement device_busy. We
1381 * must return with queue_lock held.
1383 * Decrementing device_busy without checking it is OK, as all such
1384 * cases (host limits or settings) should run the queue at some
1387 spin_lock_irq(q->queue_lock);
1388 blk_requeue_request(q, req);
1389 sdev->device_busy--;
1390 if(sdev->device_busy == 0)
1393 /* must be careful here...if we trigger the ->remove() function
1394 * we cannot be holding the q lock */
1395 spin_unlock_irq(q->queue_lock);
1396 put_device(&sdev->sdev_gendev);
1397 spin_lock_irq(q->queue_lock);
1400 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1402 struct device *host_dev;
1403 u64 bounce_limit = 0xffffffff;
1405 if (shost->unchecked_isa_dma)
1406 return BLK_BOUNCE_ISA;
1408 * Platforms with virtual-DMA translation
1409 * hardware have no practical limit.
1411 if (!PCI_DMA_BUS_IS_PHYS)
1412 return BLK_BOUNCE_ANY;
1414 host_dev = scsi_get_device(shost);
1415 if (host_dev && host_dev->dma_mask)
1416 bounce_limit = *host_dev->dma_mask;
1418 return bounce_limit;
1420 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1422 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1424 struct Scsi_Host *shost = sdev->host;
1425 struct request_queue *q;
1427 q = blk_init_queue(scsi_request_fn, &sdev->sdev_lock);
1431 blk_queue_prep_rq(q, scsi_prep_fn);
1433 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1434 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1435 blk_queue_max_sectors(q, shost->max_sectors);
1436 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1437 blk_queue_segment_boundary(q, shost->dma_boundary);
1438 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1441 * ordered tags are superior to flush ordering
1443 if (shost->ordered_tag)
1444 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1445 else if (shost->ordered_flush) {
1446 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1447 q->prepare_flush_fn = scsi_prepare_flush_fn;
1448 q->end_flush_fn = scsi_end_flush_fn;
1451 if (!shost->use_clustering)
1452 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1456 void scsi_free_queue(struct request_queue *q)
1458 blk_cleanup_queue(q);
1462 * Function: scsi_block_requests()
1464 * Purpose: Utility function used by low-level drivers to prevent further
1465 * commands from being queued to the device.
1467 * Arguments: shost - Host in question
1471 * Lock status: No locks are assumed held.
1473 * Notes: There is no timer nor any other means by which the requests
1474 * get unblocked other than the low-level driver calling
1475 * scsi_unblock_requests().
1477 void scsi_block_requests(struct Scsi_Host *shost)
1479 shost->host_self_blocked = 1;
1481 EXPORT_SYMBOL(scsi_block_requests);
1484 * Function: scsi_unblock_requests()
1486 * Purpose: Utility function used by low-level drivers to allow further
1487 * commands from being queued to the device.
1489 * Arguments: shost - Host in question
1493 * Lock status: No locks are assumed held.
1495 * Notes: There is no timer nor any other means by which the requests
1496 * get unblocked other than the low-level driver calling
1497 * scsi_unblock_requests().
1499 * This is done as an API function so that changes to the
1500 * internals of the scsi mid-layer won't require wholesale
1501 * changes to drivers that use this feature.
1503 void scsi_unblock_requests(struct Scsi_Host *shost)
1505 shost->host_self_blocked = 0;
1506 scsi_run_host_queues(shost);
1508 EXPORT_SYMBOL(scsi_unblock_requests);
1510 int __init scsi_init_queue(void)
1514 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1515 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1516 int size = sgp->size * sizeof(struct scatterlist);
1518 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1519 SLAB_HWCACHE_ALIGN, NULL, NULL);
1521 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1525 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1526 mempool_alloc_slab, mempool_free_slab,
1529 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1537 void scsi_exit_queue(void)
1541 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1542 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1543 mempool_destroy(sgp->pool);
1544 kmem_cache_destroy(sgp->slab);
1548 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1549 * six bytes if necessary.
1550 * @sreq: SCSI request to fill in with the MODE_SENSE
1551 * @dbd: set if mode sense will allow block descriptors to be returned
1552 * @modepage: mode page being requested
1553 * @buffer: request buffer (may not be smaller than eight bytes)
1554 * @len: length of request buffer.
1555 * @timeout: command timeout
1556 * @retries: number of retries before failing
1557 * @data: returns a structure abstracting the mode header data
1559 * Returns zero if unsuccessful, or the header offset (either 4
1560 * or 8 depending on whether a six or ten byte command was
1561 * issued) if successful.
1564 __scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
1565 unsigned char *buffer, int len, int timeout, int retries,
1566 struct scsi_mode_data *data) {
1567 unsigned char cmd[12];
1571 memset(data, 0, sizeof(*data));
1572 memset(&cmd[0], 0, 12);
1573 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1577 use_10_for_ms = sreq->sr_device->use_10_for_ms;
1579 if (use_10_for_ms) {
1583 cmd[0] = MODE_SENSE_10;
1590 cmd[0] = MODE_SENSE;
1595 sreq->sr_cmd_len = 0;
1596 memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
1597 sreq->sr_data_direction = DMA_FROM_DEVICE;
1599 memset(buffer, 0, len);
1601 scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
1603 /* This code looks awful: what it's doing is making sure an
1604 * ILLEGAL REQUEST sense return identifies the actual command
1605 * byte as the problem. MODE_SENSE commands can return
1606 * ILLEGAL REQUEST if the code page isn't supported */
1608 if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
1609 (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
1610 struct scsi_sense_hdr sshdr;
1612 if (scsi_request_normalize_sense(sreq, &sshdr)) {
1613 if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
1614 (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
1616 * Invalid command operation code
1618 sreq->sr_device->use_10_for_ms = 0;
1624 if(scsi_status_is_good(sreq->sr_result)) {
1625 data->header_length = header_length;
1627 data->length = buffer[0]*256 + buffer[1] + 2;
1628 data->medium_type = buffer[2];
1629 data->device_specific = buffer[3];
1630 data->longlba = buffer[4] & 0x01;
1631 data->block_descriptor_length = buffer[6]*256
1634 data->length = buffer[0] + 1;
1635 data->medium_type = buffer[1];
1636 data->device_specific = buffer[2];
1637 data->block_descriptor_length = buffer[3];
1641 return sreq->sr_result;
1643 EXPORT_SYMBOL(__scsi_mode_sense);
1646 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1647 * six bytes if necessary.
1648 * @sdev: scsi device to send command to.
1649 * @dbd: set if mode sense will disable block descriptors in the return
1650 * @modepage: mode page being requested
1651 * @buffer: request buffer (may not be smaller than eight bytes)
1652 * @len: length of request buffer.
1653 * @timeout: command timeout
1654 * @retries: number of retries before failing
1656 * Returns zero if unsuccessful, or the header offset (either 4
1657 * or 8 depending on whether a six or ten byte command was
1658 * issued) if successful.
1661 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1662 unsigned char *buffer, int len, int timeout, int retries,
1663 struct scsi_mode_data *data)
1665 struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1671 ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
1672 timeout, retries, data);
1674 scsi_release_request(sreq);
1678 EXPORT_SYMBOL(scsi_mode_sense);
1681 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1683 struct scsi_request *sreq;
1685 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1689 sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1693 sreq->sr_data_direction = DMA_NONE;
1694 scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
1696 if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
1697 struct scsi_sense_hdr sshdr;
1699 if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
1700 ((sshdr.sense_key == UNIT_ATTENTION) ||
1701 (sshdr.sense_key == NOT_READY))) {
1703 sreq->sr_result = 0;
1706 result = sreq->sr_result;
1707 scsi_release_request(sreq);
1710 EXPORT_SYMBOL(scsi_test_unit_ready);
1713 * scsi_device_set_state - Take the given device through the device
1715 * @sdev: scsi device to change the state of.
1716 * @state: state to change to.
1718 * Returns zero if unsuccessful or an error if the requested
1719 * transition is illegal.
1722 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1724 enum scsi_device_state oldstate = sdev->sdev_state;
1726 if (state == oldstate)
1731 /* There are no legal states that come back to
1732 * created. This is the manually initialised start
1802 sdev->sdev_state = state;
1806 SCSI_LOG_ERROR_RECOVERY(1,
1807 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1808 "Illegal state transition %s->%s\n",
1809 scsi_device_state_name(oldstate),
1810 scsi_device_state_name(state))
1814 EXPORT_SYMBOL(scsi_device_set_state);
1817 * scsi_device_quiesce - Block user issued commands.
1818 * @sdev: scsi device to quiesce.
1820 * This works by trying to transition to the SDEV_QUIESCE state
1821 * (which must be a legal transition). When the device is in this
1822 * state, only special requests will be accepted, all others will
1823 * be deferred. Since special requests may also be requeued requests,
1824 * a successful return doesn't guarantee the device will be
1825 * totally quiescent.
1827 * Must be called with user context, may sleep.
1829 * Returns zero if unsuccessful or an error if not.
1832 scsi_device_quiesce(struct scsi_device *sdev)
1834 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1838 scsi_run_queue(sdev->request_queue);
1839 while (sdev->device_busy) {
1840 msleep_interruptible(200);
1841 scsi_run_queue(sdev->request_queue);
1845 EXPORT_SYMBOL(scsi_device_quiesce);
1848 * scsi_device_resume - Restart user issued commands to a quiesced device.
1849 * @sdev: scsi device to resume.
1851 * Moves the device from quiesced back to running and restarts the
1854 * Must be called with user context, may sleep.
1857 scsi_device_resume(struct scsi_device *sdev)
1859 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1861 scsi_run_queue(sdev->request_queue);
1863 EXPORT_SYMBOL(scsi_device_resume);
1866 device_quiesce_fn(struct scsi_device *sdev, void *data)
1868 scsi_device_quiesce(sdev);
1872 scsi_target_quiesce(struct scsi_target *starget)
1874 starget_for_each_device(starget, NULL, device_quiesce_fn);
1876 EXPORT_SYMBOL(scsi_target_quiesce);
1879 device_resume_fn(struct scsi_device *sdev, void *data)
1881 scsi_device_resume(sdev);
1885 scsi_target_resume(struct scsi_target *starget)
1887 starget_for_each_device(starget, NULL, device_resume_fn);
1889 EXPORT_SYMBOL(scsi_target_resume);
1892 * scsi_internal_device_block - internal function to put a device
1893 * temporarily into the SDEV_BLOCK state
1894 * @sdev: device to block
1896 * Block request made by scsi lld's to temporarily stop all
1897 * scsi commands on the specified device. Called from interrupt
1898 * or normal process context.
1900 * Returns zero if successful or error if not
1903 * This routine transitions the device to the SDEV_BLOCK state
1904 * (which must be a legal transition). When the device is in this
1905 * state, all commands are deferred until the scsi lld reenables
1906 * the device with scsi_device_unblock or device_block_tmo fires.
1907 * This routine assumes the host_lock is held on entry.
1910 scsi_internal_device_block(struct scsi_device *sdev)
1912 request_queue_t *q = sdev->request_queue;
1913 unsigned long flags;
1916 err = scsi_device_set_state(sdev, SDEV_BLOCK);
1921 * The device has transitioned to SDEV_BLOCK. Stop the
1922 * block layer from calling the midlayer with this device's
1925 spin_lock_irqsave(q->queue_lock, flags);
1927 spin_unlock_irqrestore(q->queue_lock, flags);
1931 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
1934 * scsi_internal_device_unblock - resume a device after a block request
1935 * @sdev: device to resume
1937 * Called by scsi lld's or the midlayer to restart the device queue
1938 * for the previously suspended scsi device. Called from interrupt or
1939 * normal process context.
1941 * Returns zero if successful or error if not.
1944 * This routine transitions the device to the SDEV_RUNNING state
1945 * (which must be a legal transition) allowing the midlayer to
1946 * goose the queue for this device. This routine assumes the
1947 * host_lock is held upon entry.
1950 scsi_internal_device_unblock(struct scsi_device *sdev)
1952 request_queue_t *q = sdev->request_queue;
1954 unsigned long flags;
1957 * Try to transition the scsi device to SDEV_RUNNING
1958 * and goose the device queue if successful.
1960 err = scsi_device_set_state(sdev, SDEV_RUNNING);
1964 spin_lock_irqsave(q->queue_lock, flags);
1966 spin_unlock_irqrestore(q->queue_lock, flags);
1970 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
1973 device_block(struct scsi_device *sdev, void *data)
1975 scsi_internal_device_block(sdev);
1979 target_block(struct device *dev, void *data)
1981 if (scsi_is_target_device(dev))
1982 starget_for_each_device(to_scsi_target(dev), NULL,
1988 scsi_target_block(struct device *dev)
1990 if (scsi_is_target_device(dev))
1991 starget_for_each_device(to_scsi_target(dev), NULL,
1994 device_for_each_child(dev, NULL, target_block);
1996 EXPORT_SYMBOL_GPL(scsi_target_block);
1999 device_unblock(struct scsi_device *sdev, void *data)
2001 scsi_internal_device_unblock(sdev);
2005 target_unblock(struct device *dev, void *data)
2007 if (scsi_is_target_device(dev))
2008 starget_for_each_device(to_scsi_target(dev), NULL,
2014 scsi_target_unblock(struct device *dev)
2016 if (scsi_is_target_device(dev))
2017 starget_for_each_device(to_scsi_target(dev), NULL,
2020 device_for_each_child(dev, NULL, target_unblock);
2022 EXPORT_SYMBOL_GPL(scsi_target_unblock);