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,
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 * We are inserting the command into the ml queue. First, we
132 * cancel the timer, so it doesn't time out.
134 scsi_delete_timer(cmd);
137 * Next, set the appropriate busy bit for the device/host.
139 * If the host/device isn't busy, assume that something actually
140 * completed, and that we should be able to queue a command now.
142 * Note that the prior mid-layer assumption that any host could
143 * always queue at least one command is now broken. The mid-layer
144 * will implement a user specifiable stall (see
145 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
146 * if a command is requeued with no other commands outstanding
147 * either for the device or for the host.
149 if (reason == SCSI_MLQUEUE_HOST_BUSY)
150 host->host_blocked = host->max_host_blocked;
151 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
152 device->device_blocked = device->max_device_blocked;
155 * Register the fact that we own the thing for now.
157 cmd->state = SCSI_STATE_MLQUEUE;
158 cmd->owner = SCSI_OWNER_MIDLEVEL;
161 * Decrement the counters, since these commands are no longer
162 * active on the host/device.
164 scsi_device_unbusy(device);
167 * Requeue this command. It will go before all other commands
168 * that are already in the queue.
170 * NOTE: there is magic here about the way the queue is plugged if
171 * we have no outstanding commands.
173 * Although we *don't* plug the queue, we call the request
174 * function. The SCSI request function detects the blocked condition
175 * and plugs the queue appropriately.
177 spin_lock_irqsave(q->queue_lock, flags);
178 blk_requeue_request(q, cmd->request);
179 spin_unlock_irqrestore(q->queue_lock, flags);
187 * Function: scsi_do_req
189 * Purpose: Queue a SCSI request
191 * Arguments: sreq - command descriptor.
192 * cmnd - actual SCSI command to be performed.
193 * buffer - data buffer.
194 * bufflen - size of data buffer.
195 * done - completion function to be run.
196 * timeout - how long to let it run before timeout.
197 * retries - number of retries we allow.
199 * Lock status: No locks held upon entry.
203 * Notes: This function is only used for queueing requests for things
204 * like ioctls and character device requests - this is because
205 * we essentially just inject a request into the queue for the
208 * In order to support the scsi_device_quiesce function, we
209 * now inject requests on the *head* of the device queue
210 * rather than the tail.
212 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
213 void *buffer, unsigned bufflen,
214 void (*done)(struct scsi_cmnd *),
215 int timeout, int retries)
218 * If the upper level driver is reusing these things, then
219 * we should release the low-level block now. Another one will
220 * be allocated later when this request is getting queued.
222 __scsi_release_request(sreq);
225 * Our own function scsi_done (which marks the host as not busy,
226 * disables the timeout counter, etc) will be called by us or by the
227 * scsi_hosts[host].queuecommand() function needs to also call
228 * the completion function for the high level driver.
230 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
231 sreq->sr_bufflen = bufflen;
232 sreq->sr_buffer = buffer;
233 sreq->sr_allowed = retries;
234 sreq->sr_done = done;
235 sreq->sr_timeout_per_command = timeout;
237 if (sreq->sr_cmd_len == 0)
238 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
241 * head injection *required* here otherwise quiesce won't work
243 scsi_insert_special_req(sreq, 1);
245 EXPORT_SYMBOL(scsi_do_req);
247 static void scsi_wait_done(struct scsi_cmnd *cmd)
249 struct request *req = cmd->request;
250 struct request_queue *q = cmd->device->request_queue;
253 req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
255 spin_lock_irqsave(q->queue_lock, flags);
256 if (blk_rq_tagged(req))
257 blk_queue_end_tag(q, req);
258 spin_unlock_irqrestore(q->queue_lock, flags);
261 complete(req->waiting);
264 /* This is the end routine we get to if a command was never attached
265 * to the request. Simply complete the request without changing
266 * rq_status; this will cause a DRIVER_ERROR. */
267 static void scsi_wait_req_end_io(struct request *req)
269 BUG_ON(!req->waiting);
271 complete(req->waiting);
274 void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
275 unsigned bufflen, int timeout, int retries)
277 DECLARE_COMPLETION(wait);
279 sreq->sr_request->waiting = &wait;
280 sreq->sr_request->rq_status = RQ_SCSI_BUSY;
281 sreq->sr_request->end_io = scsi_wait_req_end_io;
282 scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
284 wait_for_completion(&wait);
285 sreq->sr_request->waiting = NULL;
286 if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
287 sreq->sr_result |= (DRIVER_ERROR << 24);
289 __scsi_release_request(sreq);
291 EXPORT_SYMBOL(scsi_wait_req);
294 * Function: scsi_init_cmd_errh()
296 * Purpose: Initialize cmd fields related to error handling.
298 * Arguments: cmd - command that is ready to be queued.
302 * Notes: This function has the job of initializing a number of
303 * fields related to error handling. Typically this will
304 * be called once for each command, as required.
306 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
308 cmd->owner = SCSI_OWNER_MIDLEVEL;
309 cmd->serial_number = 0;
310 cmd->abort_reason = 0;
312 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
314 if (cmd->cmd_len == 0)
315 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
318 * We need saved copies of a number of fields - this is because
319 * error handling may need to overwrite these with different values
320 * to run different commands, and once error handling is complete,
321 * we will need to restore these values prior to running the actual
324 cmd->old_use_sg = cmd->use_sg;
325 cmd->old_cmd_len = cmd->cmd_len;
326 cmd->sc_old_data_direction = cmd->sc_data_direction;
327 cmd->old_underflow = cmd->underflow;
328 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
329 cmd->buffer = cmd->request_buffer;
330 cmd->bufflen = cmd->request_bufflen;
331 cmd->abort_reason = 0;
337 * Function: scsi_setup_cmd_retry()
339 * Purpose: Restore the command state for a retry
341 * Arguments: cmd - command to be restored
345 * Notes: Immediately prior to retrying a command, we need
346 * to restore certain fields that we saved above.
348 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
350 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
351 cmd->request_buffer = cmd->buffer;
352 cmd->request_bufflen = cmd->bufflen;
353 cmd->use_sg = cmd->old_use_sg;
354 cmd->cmd_len = cmd->old_cmd_len;
355 cmd->sc_data_direction = cmd->sc_old_data_direction;
356 cmd->underflow = cmd->old_underflow;
359 void scsi_device_unbusy(struct scsi_device *sdev)
361 struct Scsi_Host *shost = sdev->host;
364 spin_lock_irqsave(shost->host_lock, flags);
366 if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
368 scsi_eh_wakeup(shost);
369 spin_unlock(shost->host_lock);
370 spin_lock(sdev->request_queue->queue_lock);
372 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
376 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
377 * and call blk_run_queue for all the scsi_devices on the target -
378 * including current_sdev first.
380 * Called with *no* scsi locks held.
382 static void scsi_single_lun_run(struct scsi_device *current_sdev)
384 struct Scsi_Host *shost = current_sdev->host;
385 struct scsi_device *sdev, *tmp;
386 struct scsi_target *starget = scsi_target(current_sdev);
389 spin_lock_irqsave(shost->host_lock, flags);
390 starget->starget_sdev_user = NULL;
391 spin_unlock_irqrestore(shost->host_lock, flags);
394 * Call blk_run_queue for all LUNs on the target, starting with
395 * current_sdev. We race with others (to set starget_sdev_user),
396 * but in most cases, we will be first. Ideally, each LU on the
397 * target would get some limited time or requests on the target.
399 blk_run_queue(current_sdev->request_queue);
401 spin_lock_irqsave(shost->host_lock, flags);
402 if (starget->starget_sdev_user)
404 list_for_each_entry_safe(sdev, tmp, &starget->devices,
405 same_target_siblings) {
406 if (sdev == current_sdev)
408 if (scsi_device_get(sdev))
411 spin_unlock_irqrestore(shost->host_lock, flags);
412 blk_run_queue(sdev->request_queue);
413 spin_lock_irqsave(shost->host_lock, flags);
415 scsi_device_put(sdev);
418 spin_unlock_irqrestore(shost->host_lock, flags);
422 * Function: scsi_run_queue()
424 * Purpose: Select a proper request queue to serve next
426 * Arguments: q - last request's queue
430 * Notes: The previous command was completely finished, start
431 * a new one if possible.
433 static void scsi_run_queue(struct request_queue *q)
435 struct scsi_device *sdev = q->queuedata;
436 struct Scsi_Host *shost = sdev->host;
439 if (sdev->single_lun)
440 scsi_single_lun_run(sdev);
442 spin_lock_irqsave(shost->host_lock, flags);
443 while (!list_empty(&shost->starved_list) &&
444 !shost->host_blocked && !shost->host_self_blocked &&
445 !((shost->can_queue > 0) &&
446 (shost->host_busy >= shost->can_queue))) {
448 * As long as shost is accepting commands and we have
449 * starved queues, call blk_run_queue. scsi_request_fn
450 * drops the queue_lock and can add us back to the
453 * host_lock protects the starved_list and starved_entry.
454 * scsi_request_fn must get the host_lock before checking
455 * or modifying starved_list or starved_entry.
457 sdev = list_entry(shost->starved_list.next,
458 struct scsi_device, starved_entry);
459 list_del_init(&sdev->starved_entry);
460 spin_unlock_irqrestore(shost->host_lock, flags);
462 blk_run_queue(sdev->request_queue);
464 spin_lock_irqsave(shost->host_lock, flags);
465 if (unlikely(!list_empty(&sdev->starved_entry)))
467 * sdev lost a race, and was put back on the
468 * starved list. This is unlikely but without this
469 * in theory we could loop forever.
473 spin_unlock_irqrestore(shost->host_lock, flags);
479 * Function: scsi_requeue_command()
481 * Purpose: Handle post-processing of completed commands.
483 * Arguments: q - queue to operate on
484 * cmd - command that may need to be requeued.
488 * Notes: After command completion, there may be blocks left
489 * over which weren't finished by the previous command
490 * this can be for a number of reasons - the main one is
491 * I/O errors in the middle of the request, in which case
492 * we need to request the blocks that come after the bad
495 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
499 cmd->request->flags &= ~REQ_DONTPREP;
501 spin_lock_irqsave(q->queue_lock, flags);
502 blk_requeue_request(q, cmd->request);
503 spin_unlock_irqrestore(q->queue_lock, flags);
508 void scsi_next_command(struct scsi_cmnd *cmd)
510 struct request_queue *q = cmd->device->request_queue;
512 scsi_put_command(cmd);
516 void scsi_run_host_queues(struct Scsi_Host *shost)
518 struct scsi_device *sdev;
520 shost_for_each_device(sdev, shost)
521 scsi_run_queue(sdev->request_queue);
525 * Function: scsi_end_request()
527 * Purpose: Post-processing of completed commands (usually invoked at end
528 * of upper level post-processing and scsi_io_completion).
530 * Arguments: cmd - command that is complete.
531 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
532 * bytes - number of bytes of completed I/O
533 * requeue - indicates whether we should requeue leftovers.
535 * Lock status: Assumed that lock is not held upon entry.
537 * Returns: cmd if requeue done or required, NULL otherwise
539 * Notes: This is called for block device requests in order to
540 * mark some number of sectors as complete.
542 * We are guaranteeing that the request queue will be goosed
543 * at some point during this call.
545 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
546 int bytes, int requeue)
548 request_queue_t *q = cmd->device->request_queue;
549 struct request *req = cmd->request;
553 * If there are blocks left over at the end, set up the command
554 * to queue the remainder of them.
556 if (end_that_request_chunk(req, uptodate, bytes)) {
557 int leftover = (req->hard_nr_sectors << 9);
559 if (blk_pc_request(req))
560 leftover = req->data_len;
562 /* kill remainder if no retrys */
563 if (!uptodate && blk_noretry_request(req))
564 end_that_request_chunk(req, 0, leftover);
568 * Bleah. Leftovers again. Stick the
569 * leftovers in the front of the
570 * queue, and goose the queue again.
572 scsi_requeue_command(q, cmd);
578 add_disk_randomness(req->rq_disk);
580 spin_lock_irqsave(q->queue_lock, flags);
581 if (blk_rq_tagged(req))
582 blk_queue_end_tag(q, req);
583 end_that_request_last(req);
584 spin_unlock_irqrestore(q->queue_lock, flags);
587 * This will goose the queue request function at the end, so we don't
588 * need to worry about launching another command.
590 scsi_next_command(cmd);
594 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
596 struct scsi_host_sg_pool *sgp;
597 struct scatterlist *sgl;
599 BUG_ON(!cmd->use_sg);
601 switch (cmd->use_sg) {
611 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
615 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
619 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
630 sgp = scsi_sg_pools + cmd->sglist_len;
631 sgl = mempool_alloc(sgp->pool, gfp_mask);
633 memset(sgl, 0, sgp->size);
637 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
639 struct scsi_host_sg_pool *sgp;
641 BUG_ON(index > SG_MEMPOOL_NR);
643 sgp = scsi_sg_pools + index;
644 mempool_free(sgl, sgp->pool);
648 * Function: scsi_release_buffers()
650 * Purpose: Completion processing for block device I/O requests.
652 * Arguments: cmd - command that we are bailing.
654 * Lock status: Assumed that no lock is held upon entry.
658 * Notes: In the event that an upper level driver rejects a
659 * command, we must release resources allocated during
660 * the __init_io() function. Primarily this would involve
661 * the scatter-gather table, and potentially any bounce
664 static void scsi_release_buffers(struct scsi_cmnd *cmd)
666 struct request *req = cmd->request;
669 * Free up any indirection buffers we allocated for DMA purposes.
672 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
673 else if (cmd->request_buffer != req->buffer)
674 kfree(cmd->request_buffer);
677 * Zero these out. They now point to freed memory, and it is
678 * dangerous to hang onto the pointers.
682 cmd->request_buffer = NULL;
683 cmd->request_bufflen = 0;
687 * Function: scsi_io_completion()
689 * Purpose: Completion processing for block device I/O requests.
691 * Arguments: cmd - command that is finished.
693 * Lock status: Assumed that no lock is held upon entry.
697 * Notes: This function is matched in terms of capabilities to
698 * the function that created the scatter-gather list.
699 * In other words, if there are no bounce buffers
700 * (the normal case for most drivers), we don't need
701 * the logic to deal with cleaning up afterwards.
703 * We must do one of several things here:
705 * a) Call scsi_end_request. This will finish off the
706 * specified number of sectors. If we are done, the
707 * command block will be released, and the queue
708 * function will be goosed. If we are not done, then
709 * scsi_end_request will directly goose the queue.
711 * b) We can just use scsi_requeue_command() here. This would
712 * be used if we just wanted to retry, for example.
714 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
715 unsigned int block_bytes)
717 int result = cmd->result;
718 int this_count = cmd->bufflen;
719 request_queue_t *q = cmd->device->request_queue;
720 struct request *req = cmd->request;
721 int clear_errors = 1;
722 struct scsi_sense_hdr sshdr;
724 int sense_deferred = 0;
726 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
730 * Free up any indirection buffers we allocated for DMA purposes.
731 * For the case of a READ, we need to copy the data out of the
732 * bounce buffer and into the real buffer.
735 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
736 else if (cmd->buffer != req->buffer) {
737 if (rq_data_dir(req) == READ) {
739 char *to = bio_kmap_irq(req->bio, &flags);
740 memcpy(to, cmd->buffer, cmd->bufflen);
741 bio_kunmap_irq(to, &flags);
747 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
749 sense_deferred = scsi_sense_is_deferred(&sshdr);
751 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
752 req->errors = result;
755 if (sense_valid && req->sense) {
757 * SG_IO wants current and deferred errors
759 int len = 8 + cmd->sense_buffer[7];
761 if (len > SCSI_SENSE_BUFFERSIZE)
762 len = SCSI_SENSE_BUFFERSIZE;
763 memcpy(req->sense, cmd->sense_buffer, len);
764 req->sense_len = len;
767 req->data_len = cmd->resid;
771 * Zero these out. They now point to freed memory, and it is
772 * dangerous to hang onto the pointers.
776 cmd->request_buffer = NULL;
777 cmd->request_bufflen = 0;
780 * Next deal with any sectors which we were able to correctly
783 if (good_bytes >= 0) {
784 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
785 req->nr_sectors, good_bytes));
786 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
791 * If multiple sectors are requested in one buffer, then
792 * they will have been finished off by the first command.
793 * If not, then we have a multi-buffer command.
795 * If block_bytes != 0, it means we had a medium error
796 * of some sort, and that we want to mark some number of
797 * sectors as not uptodate. Thus we want to inhibit
798 * requeueing right here - we will requeue down below
799 * when we handle the bad sectors.
801 cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
804 * If the command completed without error, then either finish off the
805 * rest of the command, or start a new one.
807 if (result == 0 || cmd == NULL ) {
812 * Now, if we were good little boys and girls, Santa left us a request
813 * sense buffer. We can extract information from this, so we
814 * can choose a block to remap, etc.
816 if (sense_valid && !sense_deferred) {
817 switch (sshdr.sense_key) {
819 if (cmd->device->removable) {
820 /* detected disc change. set a bit
821 * and quietly refuse further access.
823 cmd->device->changed = 1;
824 cmd = scsi_end_request(cmd, 0,
829 * Must have been a power glitch, or a
830 * bus reset. Could not have been a
831 * media change, so we just retry the
832 * request and see what happens.
834 scsi_requeue_command(q, cmd);
838 case ILLEGAL_REQUEST:
840 * If we had an ILLEGAL REQUEST returned, then we may
841 * have performed an unsupported command. The only
842 * thing this should be would be a ten byte read where
843 * only a six byte read was supported. Also, on a
844 * system where READ CAPACITY failed, we may have read
845 * past the end of the disk.
847 if (cmd->device->use_10_for_rw &&
848 (cmd->cmnd[0] == READ_10 ||
849 cmd->cmnd[0] == WRITE_10)) {
850 cmd->device->use_10_for_rw = 0;
852 * This will cause a retry with a 6-byte
855 scsi_requeue_command(q, cmd);
858 cmd = scsi_end_request(cmd, 0, this_count, 1);
864 * If the device is in the process of becoming ready,
867 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
868 scsi_requeue_command(q, cmd);
871 printk(KERN_INFO "Device %s not ready.\n",
872 req->rq_disk ? req->rq_disk->disk_name : "");
873 cmd = scsi_end_request(cmd, 0, this_count, 1);
875 case VOLUME_OVERFLOW:
876 printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
877 cmd->device->host->host_no,
878 (int)cmd->device->channel,
879 (int)cmd->device->id, (int)cmd->device->lun);
880 __scsi_print_command(cmd->data_cmnd);
881 scsi_print_sense("", cmd);
882 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
887 } /* driver byte != 0 */
888 if (host_byte(result) == DID_RESET) {
890 * Third party bus reset or reset for error
891 * recovery reasons. Just retry the request
892 * and see what happens.
894 scsi_requeue_command(q, cmd);
898 printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
899 "= 0x%x\n", cmd->device->host->host_no,
900 cmd->device->channel,
902 cmd->device->lun, result);
904 if (driver_byte(result) & DRIVER_SENSE)
905 scsi_print_sense("", cmd);
907 * Mark a single buffer as not uptodate. Queue the remainder.
908 * We sometimes get this cruft in the event that a medium error
909 * isn't properly reported.
911 block_bytes = req->hard_cur_sectors << 9;
913 block_bytes = req->data_len;
914 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
917 EXPORT_SYMBOL(scsi_io_completion);
920 * Function: scsi_init_io()
922 * Purpose: SCSI I/O initialize function.
924 * Arguments: cmd - Command descriptor we wish to initialize
926 * Returns: 0 on success
927 * BLKPREP_DEFER if the failure is retryable
928 * BLKPREP_KILL if the failure is fatal
930 static int scsi_init_io(struct scsi_cmnd *cmd)
932 struct request *req = cmd->request;
933 struct scatterlist *sgpnt;
937 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
939 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
940 cmd->request_bufflen = req->data_len;
941 cmd->request_buffer = req->data;
942 req->buffer = req->data;
948 * we used to not use scatter-gather for single segment request,
949 * but now we do (it makes highmem I/O easier to support without
952 cmd->use_sg = req->nr_phys_segments;
955 * if sg table allocation fails, requeue request later.
957 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
958 if (unlikely(!sgpnt))
959 return BLKPREP_DEFER;
961 cmd->request_buffer = (char *) sgpnt;
962 cmd->request_bufflen = req->nr_sectors << 9;
963 if (blk_pc_request(req))
964 cmd->request_bufflen = req->data_len;
968 * Next, walk the list, and fill in the addresses and sizes of
971 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
974 * mapped well, send it off
976 if (likely(count <= cmd->use_sg)) {
981 printk(KERN_ERR "Incorrect number of segments after building list\n");
982 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
983 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
984 req->current_nr_sectors);
986 /* release the command and kill it */
987 scsi_release_buffers(cmd);
988 scsi_put_command(cmd);
992 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
994 struct scsi_device *sdev = q->queuedata;
995 struct scsi_driver *drv;
997 if (sdev->sdev_state == SDEV_RUNNING) {
998 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1000 if (drv->prepare_flush)
1001 return drv->prepare_flush(q, rq);
1007 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
1009 struct scsi_device *sdev = q->queuedata;
1010 struct request *flush_rq = rq->end_io_data;
1011 struct scsi_driver *drv;
1013 if (flush_rq->errors) {
1014 printk("scsi: barrier error, disabling flush support\n");
1015 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1018 if (sdev->sdev_state == SDEV_RUNNING) {
1019 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1020 drv->end_flush(q, rq);
1024 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1025 sector_t *error_sector)
1027 struct scsi_device *sdev = q->queuedata;
1028 struct scsi_driver *drv;
1030 if (sdev->sdev_state != SDEV_RUNNING)
1033 drv = *(struct scsi_driver **) disk->private_data;
1034 if (drv->issue_flush)
1035 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1040 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1042 struct scsi_device *sdev = q->queuedata;
1043 struct scsi_cmnd *cmd;
1044 int specials_only = 0;
1047 * Just check to see if the device is online. If it isn't, we
1048 * refuse to process any commands. The device must be brought
1049 * online before trying any recovery commands
1051 if (unlikely(!scsi_device_online(sdev))) {
1052 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1053 sdev->host->host_no, sdev->id, sdev->lun);
1054 return BLKPREP_KILL;
1056 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1057 /* OK, we're not in a running state don't prep
1059 if (sdev->sdev_state == SDEV_DEL) {
1060 /* Device is fully deleted, no commands
1061 * at all allowed down */
1062 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1063 sdev->host->host_no, sdev->id, sdev->lun);
1064 return BLKPREP_KILL;
1066 /* OK, we only allow special commands (i.e. not
1067 * user initiated ones */
1068 specials_only = sdev->sdev_state;
1072 * Find the actual device driver associated with this command.
1073 * The SPECIAL requests are things like character device or
1074 * ioctls, which did not originate from ll_rw_blk. Note that
1075 * the special field is also used to indicate the cmd for
1076 * the remainder of a partially fulfilled request that can
1077 * come up when there is a medium error. We have to treat
1078 * these two cases differently. We differentiate by looking
1079 * at request->cmd, as this tells us the real story.
1081 if (req->flags & REQ_SPECIAL) {
1082 struct scsi_request *sreq = req->special;
1084 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1085 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1088 scsi_init_cmd_from_req(cmd, sreq);
1091 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1093 if(unlikely(specials_only)) {
1094 if(specials_only == SDEV_QUIESCE ||
1095 specials_only == SDEV_BLOCK)
1096 return BLKPREP_DEFER;
1098 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1099 sdev->host->host_no, sdev->id, sdev->lun);
1100 return BLKPREP_KILL;
1105 * Now try and find a command block that we can use.
1107 if (!req->special) {
1108 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1114 /* pull a tag out of the request if we have one */
1115 cmd->tag = req->tag;
1117 blk_dump_rq_flags(req, "SCSI bad req");
1118 return BLKPREP_KILL;
1121 /* note the overloading of req->special. When the tag
1122 * is active it always means cmd. If the tag goes
1123 * back for re-queueing, it may be reset */
1128 * FIXME: drop the lock here because the functions below
1129 * expect to be called without the queue lock held. Also,
1130 * previously, we dequeued the request before dropping the
1131 * lock. We hope REQ_STARTED prevents anything untoward from
1134 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1135 struct scsi_driver *drv;
1139 * This will do a couple of things:
1140 * 1) Fill in the actual SCSI command.
1141 * 2) Fill in any other upper-level specific fields
1144 * If this returns 0, it means that the request failed
1145 * (reading past end of disk, reading offline device,
1146 * etc). This won't actually talk to the device, but
1147 * some kinds of consistency checking may cause the
1148 * request to be rejected immediately.
1152 * This sets up the scatter-gather table (allocating if
1155 ret = scsi_init_io(cmd);
1156 if (ret) /* BLKPREP_KILL return also releases the command */
1160 * Initialize the actual SCSI command for this request.
1162 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1163 if (unlikely(!drv->init_command(cmd))) {
1164 scsi_release_buffers(cmd);
1165 scsi_put_command(cmd);
1166 return BLKPREP_KILL;
1171 * The request is now prepped, no need to come back here
1173 req->flags |= REQ_DONTPREP;
1177 /* If we defer, the elv_next_request() returns NULL, but the
1178 * queue must be restarted, so we plug here if no returning
1179 * command will automatically do that. */
1180 if (sdev->device_busy == 0)
1182 return BLKPREP_DEFER;
1186 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1189 * Called with the queue_lock held.
1191 static inline int scsi_dev_queue_ready(struct request_queue *q,
1192 struct scsi_device *sdev)
1194 if (sdev->device_busy >= sdev->queue_depth)
1196 if (sdev->device_busy == 0 && sdev->device_blocked) {
1198 * unblock after device_blocked iterates to zero
1200 if (--sdev->device_blocked == 0) {
1202 printk("scsi%d (%d:%d) unblocking device at"
1203 " zero depth\n", sdev->host->host_no,
1204 sdev->id, sdev->lun));
1210 if (sdev->device_blocked)
1217 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1218 * return 0. We must end up running the queue again whenever 0 is
1219 * returned, else IO can hang.
1221 * Called with host_lock held.
1223 static inline int scsi_host_queue_ready(struct request_queue *q,
1224 struct Scsi_Host *shost,
1225 struct scsi_device *sdev)
1227 if (test_bit(SHOST_RECOVERY, &shost->shost_state))
1229 if (shost->host_busy == 0 && shost->host_blocked) {
1231 * unblock after host_blocked iterates to zero
1233 if (--shost->host_blocked == 0) {
1235 printk("scsi%d unblocking host at zero depth\n",
1242 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1243 shost->host_blocked || shost->host_self_blocked) {
1244 if (list_empty(&sdev->starved_entry))
1245 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1249 /* We're OK to process the command, so we can't be starved */
1250 if (!list_empty(&sdev->starved_entry))
1251 list_del_init(&sdev->starved_entry);
1257 * Kill requests for a dead device
1259 static void scsi_kill_requests(request_queue_t *q)
1261 struct request *req;
1263 while ((req = elv_next_request(q)) != NULL) {
1264 blkdev_dequeue_request(req);
1265 req->flags |= REQ_QUIET;
1266 while (end_that_request_first(req, 0, req->nr_sectors))
1268 end_that_request_last(req);
1273 * Function: scsi_request_fn()
1275 * Purpose: Main strategy routine for SCSI.
1277 * Arguments: q - Pointer to actual queue.
1281 * Lock status: IO request lock assumed to be held when called.
1283 static void scsi_request_fn(struct request_queue *q)
1285 struct scsi_device *sdev = q->queuedata;
1286 struct Scsi_Host *shost;
1287 struct scsi_cmnd *cmd;
1288 struct request *req;
1291 printk("scsi: killing requests for dead queue\n");
1292 scsi_kill_requests(q);
1296 if(!get_device(&sdev->sdev_gendev))
1297 /* We must be tearing the block queue down already */
1301 * To start with, we keep looping until the queue is empty, or until
1302 * the host is no longer able to accept any more requests.
1305 while (!blk_queue_plugged(q)) {
1308 * get next queueable request. We do this early to make sure
1309 * that the request is fully prepared even if we cannot
1312 req = elv_next_request(q);
1313 if (!req || !scsi_dev_queue_ready(q, sdev))
1316 if (unlikely(!scsi_device_online(sdev))) {
1317 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1318 sdev->host->host_no, sdev->id, sdev->lun);
1319 blkdev_dequeue_request(req);
1320 req->flags |= REQ_QUIET;
1321 while (end_that_request_first(req, 0, req->nr_sectors))
1323 end_that_request_last(req);
1329 * Remove the request from the request list.
1331 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1332 blkdev_dequeue_request(req);
1333 sdev->device_busy++;
1335 spin_unlock(q->queue_lock);
1336 spin_lock(shost->host_lock);
1338 if (!scsi_host_queue_ready(q, shost, sdev))
1340 if (sdev->single_lun) {
1341 if (scsi_target(sdev)->starget_sdev_user &&
1342 scsi_target(sdev)->starget_sdev_user != sdev)
1344 scsi_target(sdev)->starget_sdev_user = sdev;
1349 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1350 * take the lock again.
1352 spin_unlock_irq(shost->host_lock);
1355 if (unlikely(cmd == NULL)) {
1356 printk(KERN_CRIT "impossible request in %s.\n"
1357 "please mail a stack trace to "
1358 "linux-scsi@vger.kernel.org",
1364 * Finally, initialize any error handling parameters, and set up
1365 * the timers for timeouts.
1367 scsi_init_cmd_errh(cmd);
1370 * Dispatch the command to the low-level driver.
1372 rtn = scsi_dispatch_cmd(cmd);
1373 spin_lock_irq(q->queue_lock);
1375 /* we're refusing the command; because of
1376 * the way locks get dropped, we need to
1377 * check here if plugging is required */
1378 if(sdev->device_busy == 0)
1388 spin_unlock_irq(shost->host_lock);
1391 * lock q, handle tag, requeue req, and decrement device_busy. We
1392 * must return with queue_lock held.
1394 * Decrementing device_busy without checking it is OK, as all such
1395 * cases (host limits or settings) should run the queue at some
1398 spin_lock_irq(q->queue_lock);
1399 blk_requeue_request(q, req);
1400 sdev->device_busy--;
1401 if(sdev->device_busy == 0)
1404 /* must be careful here...if we trigger the ->remove() function
1405 * we cannot be holding the q lock */
1406 spin_unlock_irq(q->queue_lock);
1407 put_device(&sdev->sdev_gendev);
1408 spin_lock_irq(q->queue_lock);
1411 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1413 struct device *host_dev;
1414 u64 bounce_limit = 0xffffffff;
1416 if (shost->unchecked_isa_dma)
1417 return BLK_BOUNCE_ISA;
1419 * Platforms with virtual-DMA translation
1420 * hardware have no practical limit.
1422 if (!PCI_DMA_BUS_IS_PHYS)
1423 return BLK_BOUNCE_ANY;
1425 host_dev = scsi_get_device(shost);
1426 if (host_dev && host_dev->dma_mask)
1427 bounce_limit = *host_dev->dma_mask;
1429 return bounce_limit;
1431 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1433 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1435 struct Scsi_Host *shost = sdev->host;
1436 struct request_queue *q;
1438 q = blk_init_queue(scsi_request_fn, NULL);
1442 blk_queue_prep_rq(q, scsi_prep_fn);
1444 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1445 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1446 blk_queue_max_sectors(q, shost->max_sectors);
1447 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1448 blk_queue_segment_boundary(q, shost->dma_boundary);
1449 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1452 * ordered tags are superior to flush ordering
1454 if (shost->ordered_tag)
1455 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1456 else if (shost->ordered_flush) {
1457 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1458 q->prepare_flush_fn = scsi_prepare_flush_fn;
1459 q->end_flush_fn = scsi_end_flush_fn;
1462 if (!shost->use_clustering)
1463 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1467 void scsi_free_queue(struct request_queue *q)
1469 blk_cleanup_queue(q);
1473 * Function: scsi_block_requests()
1475 * Purpose: Utility function used by low-level drivers to prevent further
1476 * commands from being queued to the device.
1478 * Arguments: shost - Host in question
1482 * Lock status: No locks are assumed held.
1484 * Notes: There is no timer nor any other means by which the requests
1485 * get unblocked other than the low-level driver calling
1486 * scsi_unblock_requests().
1488 void scsi_block_requests(struct Scsi_Host *shost)
1490 shost->host_self_blocked = 1;
1492 EXPORT_SYMBOL(scsi_block_requests);
1495 * Function: scsi_unblock_requests()
1497 * Purpose: Utility function used by low-level drivers to allow further
1498 * commands from being queued to the device.
1500 * Arguments: shost - Host in question
1504 * Lock status: No locks are assumed held.
1506 * Notes: There is no timer nor any other means by which the requests
1507 * get unblocked other than the low-level driver calling
1508 * scsi_unblock_requests().
1510 * This is done as an API function so that changes to the
1511 * internals of the scsi mid-layer won't require wholesale
1512 * changes to drivers that use this feature.
1514 void scsi_unblock_requests(struct Scsi_Host *shost)
1516 shost->host_self_blocked = 0;
1517 scsi_run_host_queues(shost);
1519 EXPORT_SYMBOL(scsi_unblock_requests);
1521 int __init scsi_init_queue(void)
1525 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1526 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1527 int size = sgp->size * sizeof(struct scatterlist);
1529 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1530 SLAB_HWCACHE_ALIGN, NULL, NULL);
1532 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1536 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1537 mempool_alloc_slab, mempool_free_slab,
1540 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1548 void scsi_exit_queue(void)
1552 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1553 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1554 mempool_destroy(sgp->pool);
1555 kmem_cache_destroy(sgp->slab);
1559 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1560 * six bytes if necessary.
1561 * @sreq: SCSI request to fill in with the MODE_SENSE
1562 * @dbd: set if mode sense will allow block descriptors to be returned
1563 * @modepage: mode page being requested
1564 * @buffer: request buffer (may not be smaller than eight bytes)
1565 * @len: length of request buffer.
1566 * @timeout: command timeout
1567 * @retries: number of retries before failing
1568 * @data: returns a structure abstracting the mode header data
1570 * Returns zero if unsuccessful, or the header offset (either 4
1571 * or 8 depending on whether a six or ten byte command was
1572 * issued) if successful.
1575 __scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
1576 unsigned char *buffer, int len, int timeout, int retries,
1577 struct scsi_mode_data *data) {
1578 unsigned char cmd[12];
1582 memset(data, 0, sizeof(*data));
1583 memset(&cmd[0], 0, 12);
1584 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1588 use_10_for_ms = sreq->sr_device->use_10_for_ms;
1590 if (use_10_for_ms) {
1594 cmd[0] = MODE_SENSE_10;
1601 cmd[0] = MODE_SENSE;
1606 sreq->sr_cmd_len = 0;
1607 memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
1608 sreq->sr_data_direction = DMA_FROM_DEVICE;
1610 memset(buffer, 0, len);
1612 scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
1614 /* This code looks awful: what it's doing is making sure an
1615 * ILLEGAL REQUEST sense return identifies the actual command
1616 * byte as the problem. MODE_SENSE commands can return
1617 * ILLEGAL REQUEST if the code page isn't supported */
1619 if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
1620 (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
1621 struct scsi_sense_hdr sshdr;
1623 if (scsi_request_normalize_sense(sreq, &sshdr)) {
1624 if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
1625 (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
1627 * Invalid command operation code
1629 sreq->sr_device->use_10_for_ms = 0;
1635 if(scsi_status_is_good(sreq->sr_result)) {
1636 data->header_length = header_length;
1638 data->length = buffer[0]*256 + buffer[1] + 2;
1639 data->medium_type = buffer[2];
1640 data->device_specific = buffer[3];
1641 data->longlba = buffer[4] & 0x01;
1642 data->block_descriptor_length = buffer[6]*256
1645 data->length = buffer[0] + 1;
1646 data->medium_type = buffer[1];
1647 data->device_specific = buffer[2];
1648 data->block_descriptor_length = buffer[3];
1652 return sreq->sr_result;
1654 EXPORT_SYMBOL(__scsi_mode_sense);
1657 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1658 * six bytes if necessary.
1659 * @sdev: scsi device to send command to.
1660 * @dbd: set if mode sense will disable block descriptors in the return
1661 * @modepage: mode page being requested
1662 * @buffer: request buffer (may not be smaller than eight bytes)
1663 * @len: length of request buffer.
1664 * @timeout: command timeout
1665 * @retries: number of retries before failing
1667 * Returns zero if unsuccessful, or the header offset (either 4
1668 * or 8 depending on whether a six or ten byte command was
1669 * issued) if successful.
1672 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1673 unsigned char *buffer, int len, int timeout, int retries,
1674 struct scsi_mode_data *data)
1676 struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1682 ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
1683 timeout, retries, data);
1685 scsi_release_request(sreq);
1689 EXPORT_SYMBOL(scsi_mode_sense);
1692 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1694 struct scsi_request *sreq;
1696 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1700 sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1704 sreq->sr_data_direction = DMA_NONE;
1705 scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
1707 if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
1708 struct scsi_sense_hdr sshdr;
1710 if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
1711 ((sshdr.sense_key == UNIT_ATTENTION) ||
1712 (sshdr.sense_key == NOT_READY))) {
1714 sreq->sr_result = 0;
1717 result = sreq->sr_result;
1718 scsi_release_request(sreq);
1721 EXPORT_SYMBOL(scsi_test_unit_ready);
1724 * scsi_device_set_state - Take the given device through the device
1726 * @sdev: scsi device to change the state of.
1727 * @state: state to change to.
1729 * Returns zero if unsuccessful or an error if the requested
1730 * transition is illegal.
1733 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1735 enum scsi_device_state oldstate = sdev->sdev_state;
1737 if (state == oldstate)
1742 /* There are no legal states that come back to
1743 * created. This is the manually initialised start
1813 sdev->sdev_state = state;
1817 SCSI_LOG_ERROR_RECOVERY(1,
1818 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1819 "Illegal state transition %s->%s\n",
1820 scsi_device_state_name(oldstate),
1821 scsi_device_state_name(state))
1825 EXPORT_SYMBOL(scsi_device_set_state);
1828 * scsi_device_quiesce - Block user issued commands.
1829 * @sdev: scsi device to quiesce.
1831 * This works by trying to transition to the SDEV_QUIESCE state
1832 * (which must be a legal transition). When the device is in this
1833 * state, only special requests will be accepted, all others will
1834 * be deferred. Since special requests may also be requeued requests,
1835 * a successful return doesn't guarantee the device will be
1836 * totally quiescent.
1838 * Must be called with user context, may sleep.
1840 * Returns zero if unsuccessful or an error if not.
1843 scsi_device_quiesce(struct scsi_device *sdev)
1845 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1849 scsi_run_queue(sdev->request_queue);
1850 while (sdev->device_busy) {
1851 msleep_interruptible(200);
1852 scsi_run_queue(sdev->request_queue);
1856 EXPORT_SYMBOL(scsi_device_quiesce);
1859 * scsi_device_resume - Restart user issued commands to a quiesced device.
1860 * @sdev: scsi device to resume.
1862 * Moves the device from quiesced back to running and restarts the
1865 * Must be called with user context, may sleep.
1868 scsi_device_resume(struct scsi_device *sdev)
1870 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1872 scsi_run_queue(sdev->request_queue);
1874 EXPORT_SYMBOL(scsi_device_resume);
1877 device_quiesce_fn(struct scsi_device *sdev, void *data)
1879 scsi_device_quiesce(sdev);
1883 scsi_target_quiesce(struct scsi_target *starget)
1885 starget_for_each_device(starget, NULL, device_quiesce_fn);
1887 EXPORT_SYMBOL(scsi_target_quiesce);
1890 device_resume_fn(struct scsi_device *sdev, void *data)
1892 scsi_device_resume(sdev);
1896 scsi_target_resume(struct scsi_target *starget)
1898 starget_for_each_device(starget, NULL, device_resume_fn);
1900 EXPORT_SYMBOL(scsi_target_resume);
1903 * scsi_internal_device_block - internal function to put a device
1904 * temporarily into the SDEV_BLOCK state
1905 * @sdev: device to block
1907 * Block request made by scsi lld's to temporarily stop all
1908 * scsi commands on the specified device. Called from interrupt
1909 * or normal process context.
1911 * Returns zero if successful or error if not
1914 * This routine transitions the device to the SDEV_BLOCK state
1915 * (which must be a legal transition). When the device is in this
1916 * state, all commands are deferred until the scsi lld reenables
1917 * the device with scsi_device_unblock or device_block_tmo fires.
1918 * This routine assumes the host_lock is held on entry.
1921 scsi_internal_device_block(struct scsi_device *sdev)
1923 request_queue_t *q = sdev->request_queue;
1924 unsigned long flags;
1927 err = scsi_device_set_state(sdev, SDEV_BLOCK);
1932 * The device has transitioned to SDEV_BLOCK. Stop the
1933 * block layer from calling the midlayer with this device's
1936 spin_lock_irqsave(q->queue_lock, flags);
1938 spin_unlock_irqrestore(q->queue_lock, flags);
1942 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
1945 * scsi_internal_device_unblock - resume a device after a block request
1946 * @sdev: device to resume
1948 * Called by scsi lld's or the midlayer to restart the device queue
1949 * for the previously suspended scsi device. Called from interrupt or
1950 * normal process context.
1952 * Returns zero if successful or error if not.
1955 * This routine transitions the device to the SDEV_RUNNING state
1956 * (which must be a legal transition) allowing the midlayer to
1957 * goose the queue for this device. This routine assumes the
1958 * host_lock is held upon entry.
1961 scsi_internal_device_unblock(struct scsi_device *sdev)
1963 request_queue_t *q = sdev->request_queue;
1965 unsigned long flags;
1968 * Try to transition the scsi device to SDEV_RUNNING
1969 * and goose the device queue if successful.
1971 err = scsi_device_set_state(sdev, SDEV_RUNNING);
1975 spin_lock_irqsave(q->queue_lock, flags);
1977 spin_unlock_irqrestore(q->queue_lock, flags);
1981 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
1984 device_block(struct scsi_device *sdev, void *data)
1986 scsi_internal_device_block(sdev);
1990 target_block(struct device *dev, void *data)
1992 if (scsi_is_target_device(dev))
1993 starget_for_each_device(to_scsi_target(dev), NULL,
1999 scsi_target_block(struct device *dev)
2001 if (scsi_is_target_device(dev))
2002 starget_for_each_device(to_scsi_target(dev), NULL,
2005 device_for_each_child(dev, NULL, target_block);
2007 EXPORT_SYMBOL_GPL(scsi_target_block);
2010 device_unblock(struct scsi_device *sdev, void *data)
2012 scsi_internal_device_unblock(sdev);
2016 target_unblock(struct device *dev, void *data)
2018 if (scsi_is_target_device(dev))
2019 starget_for_each_device(to_scsi_target(dev), NULL,
2025 scsi_target_unblock(struct device *dev)
2027 if (scsi_is_target_device(dev))
2028 starget_for_each_device(to_scsi_target(dev), NULL,
2031 device_for_each_child(dev, NULL, target_unblock);
2033 EXPORT_SYMBOL_GPL(scsi_target_unblock);