2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/completion.h>
13 #include <linux/kernel.h>
14 #include <linux/mempool.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/pci.h>
18 #include <linux/delay.h>
20 #include <scsi/scsi.h>
21 #include <scsi/scsi_dbg.h>
22 #include <scsi/scsi_device.h>
23 #include <scsi/scsi_driver.h>
24 #include <scsi/scsi_eh.h>
25 #include <scsi/scsi_host.h>
26 #include <scsi/scsi_request.h>
28 #include "scsi_priv.h"
29 #include "scsi_logging.h"
32 #define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
33 #define SG_MEMPOOL_SIZE 32
35 struct scsi_host_sg_pool {
42 #if (SCSI_MAX_PHYS_SEGMENTS < 32)
43 #error SCSI_MAX_PHYS_SEGMENTS is too small
46 #define SP(x) { x, "sgpool-" #x }
47 static struct scsi_host_sg_pool scsi_sg_pools[] = {
51 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
53 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
55 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
57 #if (SCSI_MAX_PHYS_SEGMENTS > 256)
58 #error SCSI_MAX_PHYS_SEGMENTS is too large
68 * Function: scsi_insert_special_req()
70 * Purpose: Insert pre-formed request into request queue.
72 * Arguments: sreq - request that is ready to be queued.
73 * at_head - boolean. True if we should insert at head
74 * of queue, false if we should insert at tail.
76 * Lock status: Assumed that lock is not held upon entry.
80 * Notes: This function is called from character device and from
81 * ioctl types of functions where the caller knows exactly
82 * what SCSI command needs to be issued. The idea is that
83 * we merely inject the command into the queue (at the head
84 * for now), and then call the queue request function to actually
87 int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
90 * Because users of this function are apt to reuse requests with no
91 * modification, we have to sanitise the request flags here
93 sreq->sr_request->flags &= ~REQ_DONTPREP;
94 blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
99 static void scsi_run_queue(struct request_queue *q);
102 * Function: scsi_queue_insert()
104 * Purpose: Insert a command in the midlevel queue.
106 * Arguments: cmd - command that we are adding to queue.
107 * reason - why we are inserting command to queue.
109 * Lock status: Assumed that lock is not held upon entry.
113 * Notes: We do this for one of two cases. Either the host is busy
114 * and it cannot accept any more commands for the time being,
115 * or the device returned QUEUE_FULL and can accept no more
117 * Notes: This could be called either from an interrupt context or a
118 * normal process context.
120 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
122 struct Scsi_Host *host = cmd->device->host;
123 struct scsi_device *device = cmd->device;
124 struct request_queue *q = device->request_queue;
128 printk("Inserting command %p into mlqueue\n", cmd));
131 * Set the appropriate busy bit for the device/host.
133 * If the host/device isn't busy, assume that something actually
134 * completed, and that we should be able to queue a command now.
136 * Note that the prior mid-layer assumption that any host could
137 * always queue at least one command is now broken. The mid-layer
138 * will implement a user specifiable stall (see
139 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
140 * if a command is requeued with no other commands outstanding
141 * either for the device or for the host.
143 if (reason == SCSI_MLQUEUE_HOST_BUSY)
144 host->host_blocked = host->max_host_blocked;
145 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
146 device->device_blocked = device->max_device_blocked;
149 * Register the fact that we own the thing for now.
151 cmd->state = SCSI_STATE_MLQUEUE;
154 * Decrement the counters, since these commands are no longer
155 * active on the host/device.
157 scsi_device_unbusy(device);
160 * Requeue this command. It will go before all other commands
161 * that are already in the queue.
163 * NOTE: there is magic here about the way the queue is plugged if
164 * we have no outstanding commands.
166 * Although we *don't* plug the queue, we call the request
167 * function. The SCSI request function detects the blocked condition
168 * and plugs the queue appropriately.
170 spin_lock_irqsave(q->queue_lock, flags);
171 blk_requeue_request(q, cmd->request);
172 spin_unlock_irqrestore(q->queue_lock, flags);
180 * Function: scsi_do_req
182 * Purpose: Queue a SCSI request
184 * Arguments: sreq - command descriptor.
185 * cmnd - actual SCSI command to be performed.
186 * buffer - data buffer.
187 * bufflen - size of data buffer.
188 * done - completion function to be run.
189 * timeout - how long to let it run before timeout.
190 * retries - number of retries we allow.
192 * Lock status: No locks held upon entry.
196 * Notes: This function is only used for queueing requests for things
197 * like ioctls and character device requests - this is because
198 * we essentially just inject a request into the queue for the
201 * In order to support the scsi_device_quiesce function, we
202 * now inject requests on the *head* of the device queue
203 * rather than the tail.
205 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
206 void *buffer, unsigned bufflen,
207 void (*done)(struct scsi_cmnd *),
208 int timeout, int retries)
211 * If the upper level driver is reusing these things, then
212 * we should release the low-level block now. Another one will
213 * be allocated later when this request is getting queued.
215 __scsi_release_request(sreq);
218 * Our own function scsi_done (which marks the host as not busy,
219 * disables the timeout counter, etc) will be called by us or by the
220 * scsi_hosts[host].queuecommand() function needs to also call
221 * the completion function for the high level driver.
223 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
224 sreq->sr_bufflen = bufflen;
225 sreq->sr_buffer = buffer;
226 sreq->sr_allowed = retries;
227 sreq->sr_done = done;
228 sreq->sr_timeout_per_command = timeout;
230 if (sreq->sr_cmd_len == 0)
231 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
234 * head injection *required* here otherwise quiesce won't work
236 scsi_insert_special_req(sreq, 1);
238 EXPORT_SYMBOL(scsi_do_req);
240 static void scsi_wait_done(struct scsi_cmnd *cmd)
242 struct request *req = cmd->request;
243 struct request_queue *q = cmd->device->request_queue;
246 req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
248 spin_lock_irqsave(q->queue_lock, flags);
249 if (blk_rq_tagged(req))
250 blk_queue_end_tag(q, req);
251 spin_unlock_irqrestore(q->queue_lock, flags);
254 complete(req->waiting);
257 /* This is the end routine we get to if a command was never attached
258 * to the request. Simply complete the request without changing
259 * rq_status; this will cause a DRIVER_ERROR. */
260 static void scsi_wait_req_end_io(struct request *req)
262 BUG_ON(!req->waiting);
264 complete(req->waiting);
267 void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
268 unsigned bufflen, int timeout, int retries)
270 DECLARE_COMPLETION(wait);
272 sreq->sr_request->waiting = &wait;
273 sreq->sr_request->rq_status = RQ_SCSI_BUSY;
274 sreq->sr_request->end_io = scsi_wait_req_end_io;
275 scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
277 wait_for_completion(&wait);
278 sreq->sr_request->waiting = NULL;
279 if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
280 sreq->sr_result |= (DRIVER_ERROR << 24);
282 __scsi_release_request(sreq);
284 EXPORT_SYMBOL(scsi_wait_req);
287 * Function: scsi_init_cmd_errh()
289 * Purpose: Initialize cmd fields related to error handling.
291 * Arguments: cmd - command that is ready to be queued.
295 * Notes: This function has the job of initializing a number of
296 * fields related to error handling. Typically this will
297 * be called once for each command, as required.
299 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
301 cmd->serial_number = 0;
303 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
305 if (cmd->cmd_len == 0)
306 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
309 * We need saved copies of a number of fields - this is because
310 * error handling may need to overwrite these with different values
311 * to run different commands, and once error handling is complete,
312 * we will need to restore these values prior to running the actual
315 cmd->old_use_sg = cmd->use_sg;
316 cmd->old_cmd_len = cmd->cmd_len;
317 cmd->sc_old_data_direction = cmd->sc_data_direction;
318 cmd->old_underflow = cmd->underflow;
319 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
320 cmd->buffer = cmd->request_buffer;
321 cmd->bufflen = cmd->request_bufflen;
327 * Function: scsi_setup_cmd_retry()
329 * Purpose: Restore the command state for a retry
331 * Arguments: cmd - command to be restored
335 * Notes: Immediately prior to retrying a command, we need
336 * to restore certain fields that we saved above.
338 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
340 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
341 cmd->request_buffer = cmd->buffer;
342 cmd->request_bufflen = cmd->bufflen;
343 cmd->use_sg = cmd->old_use_sg;
344 cmd->cmd_len = cmd->old_cmd_len;
345 cmd->sc_data_direction = cmd->sc_old_data_direction;
346 cmd->underflow = cmd->old_underflow;
349 void scsi_device_unbusy(struct scsi_device *sdev)
351 struct Scsi_Host *shost = sdev->host;
354 spin_lock_irqsave(shost->host_lock, flags);
356 if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
358 scsi_eh_wakeup(shost);
359 spin_unlock(shost->host_lock);
360 spin_lock(sdev->request_queue->queue_lock);
362 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
366 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
367 * and call blk_run_queue for all the scsi_devices on the target -
368 * including current_sdev first.
370 * Called with *no* scsi locks held.
372 static void scsi_single_lun_run(struct scsi_device *current_sdev)
374 struct Scsi_Host *shost = current_sdev->host;
375 struct scsi_device *sdev, *tmp;
376 struct scsi_target *starget = scsi_target(current_sdev);
379 spin_lock_irqsave(shost->host_lock, flags);
380 starget->starget_sdev_user = NULL;
381 spin_unlock_irqrestore(shost->host_lock, flags);
384 * Call blk_run_queue for all LUNs on the target, starting with
385 * current_sdev. We race with others (to set starget_sdev_user),
386 * but in most cases, we will be first. Ideally, each LU on the
387 * target would get some limited time or requests on the target.
389 blk_run_queue(current_sdev->request_queue);
391 spin_lock_irqsave(shost->host_lock, flags);
392 if (starget->starget_sdev_user)
394 list_for_each_entry_safe(sdev, tmp, &starget->devices,
395 same_target_siblings) {
396 if (sdev == current_sdev)
398 if (scsi_device_get(sdev))
401 spin_unlock_irqrestore(shost->host_lock, flags);
402 blk_run_queue(sdev->request_queue);
403 spin_lock_irqsave(shost->host_lock, flags);
405 scsi_device_put(sdev);
408 spin_unlock_irqrestore(shost->host_lock, flags);
412 * Function: scsi_run_queue()
414 * Purpose: Select a proper request queue to serve next
416 * Arguments: q - last request's queue
420 * Notes: The previous command was completely finished, start
421 * a new one if possible.
423 static void scsi_run_queue(struct request_queue *q)
425 struct scsi_device *sdev = q->queuedata;
426 struct Scsi_Host *shost = sdev->host;
429 if (sdev->single_lun)
430 scsi_single_lun_run(sdev);
432 spin_lock_irqsave(shost->host_lock, flags);
433 while (!list_empty(&shost->starved_list) &&
434 !shost->host_blocked && !shost->host_self_blocked &&
435 !((shost->can_queue > 0) &&
436 (shost->host_busy >= shost->can_queue))) {
438 * As long as shost is accepting commands and we have
439 * starved queues, call blk_run_queue. scsi_request_fn
440 * drops the queue_lock and can add us back to the
443 * host_lock protects the starved_list and starved_entry.
444 * scsi_request_fn must get the host_lock before checking
445 * or modifying starved_list or starved_entry.
447 sdev = list_entry(shost->starved_list.next,
448 struct scsi_device, starved_entry);
449 list_del_init(&sdev->starved_entry);
450 spin_unlock_irqrestore(shost->host_lock, flags);
452 blk_run_queue(sdev->request_queue);
454 spin_lock_irqsave(shost->host_lock, flags);
455 if (unlikely(!list_empty(&sdev->starved_entry)))
457 * sdev lost a race, and was put back on the
458 * starved list. This is unlikely but without this
459 * in theory we could loop forever.
463 spin_unlock_irqrestore(shost->host_lock, flags);
469 * Function: scsi_requeue_command()
471 * Purpose: Handle post-processing of completed commands.
473 * Arguments: q - queue to operate on
474 * cmd - command that may need to be requeued.
478 * Notes: After command completion, there may be blocks left
479 * over which weren't finished by the previous command
480 * this can be for a number of reasons - the main one is
481 * I/O errors in the middle of the request, in which case
482 * we need to request the blocks that come after the bad
485 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
489 cmd->request->flags &= ~REQ_DONTPREP;
491 spin_lock_irqsave(q->queue_lock, flags);
492 blk_requeue_request(q, cmd->request);
493 spin_unlock_irqrestore(q->queue_lock, flags);
498 void scsi_next_command(struct scsi_cmnd *cmd)
500 struct request_queue *q = cmd->device->request_queue;
502 scsi_put_command(cmd);
506 void scsi_run_host_queues(struct Scsi_Host *shost)
508 struct scsi_device *sdev;
510 shost_for_each_device(sdev, shost)
511 scsi_run_queue(sdev->request_queue);
515 * Function: scsi_end_request()
517 * Purpose: Post-processing of completed commands (usually invoked at end
518 * of upper level post-processing and scsi_io_completion).
520 * Arguments: cmd - command that is complete.
521 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
522 * bytes - number of bytes of completed I/O
523 * requeue - indicates whether we should requeue leftovers.
525 * Lock status: Assumed that lock is not held upon entry.
527 * Returns: cmd if requeue done or required, NULL otherwise
529 * Notes: This is called for block device requests in order to
530 * mark some number of sectors as complete.
532 * We are guaranteeing that the request queue will be goosed
533 * at some point during this call.
535 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
536 int bytes, int requeue)
538 request_queue_t *q = cmd->device->request_queue;
539 struct request *req = cmd->request;
543 * If there are blocks left over at the end, set up the command
544 * to queue the remainder of them.
546 if (end_that_request_chunk(req, uptodate, bytes)) {
547 int leftover = (req->hard_nr_sectors << 9);
549 if (blk_pc_request(req))
550 leftover = req->data_len;
552 /* kill remainder if no retrys */
553 if (!uptodate && blk_noretry_request(req))
554 end_that_request_chunk(req, 0, leftover);
558 * Bleah. Leftovers again. Stick the
559 * leftovers in the front of the
560 * queue, and goose the queue again.
562 scsi_requeue_command(q, cmd);
568 add_disk_randomness(req->rq_disk);
570 spin_lock_irqsave(q->queue_lock, flags);
571 if (blk_rq_tagged(req))
572 blk_queue_end_tag(q, req);
573 end_that_request_last(req);
574 spin_unlock_irqrestore(q->queue_lock, flags);
577 * This will goose the queue request function at the end, so we don't
578 * need to worry about launching another command.
580 scsi_next_command(cmd);
584 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
586 struct scsi_host_sg_pool *sgp;
587 struct scatterlist *sgl;
589 BUG_ON(!cmd->use_sg);
591 switch (cmd->use_sg) {
601 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
605 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
609 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
620 sgp = scsi_sg_pools + cmd->sglist_len;
621 sgl = mempool_alloc(sgp->pool, gfp_mask);
623 memset(sgl, 0, sgp->size);
627 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
629 struct scsi_host_sg_pool *sgp;
631 BUG_ON(index > SG_MEMPOOL_NR);
633 sgp = scsi_sg_pools + index;
634 mempool_free(sgl, sgp->pool);
638 * Function: scsi_release_buffers()
640 * Purpose: Completion processing for block device I/O requests.
642 * Arguments: cmd - command that we are bailing.
644 * Lock status: Assumed that no lock is held upon entry.
648 * Notes: In the event that an upper level driver rejects a
649 * command, we must release resources allocated during
650 * the __init_io() function. Primarily this would involve
651 * the scatter-gather table, and potentially any bounce
654 static void scsi_release_buffers(struct scsi_cmnd *cmd)
656 struct request *req = cmd->request;
659 * Free up any indirection buffers we allocated for DMA purposes.
662 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
663 else if (cmd->request_buffer != req->buffer)
664 kfree(cmd->request_buffer);
667 * Zero these out. They now point to freed memory, and it is
668 * dangerous to hang onto the pointers.
672 cmd->request_buffer = NULL;
673 cmd->request_bufflen = 0;
677 * Function: scsi_io_completion()
679 * Purpose: Completion processing for block device I/O requests.
681 * Arguments: cmd - command that is finished.
683 * Lock status: Assumed that no lock is held upon entry.
687 * Notes: This function is matched in terms of capabilities to
688 * the function that created the scatter-gather list.
689 * In other words, if there are no bounce buffers
690 * (the normal case for most drivers), we don't need
691 * the logic to deal with cleaning up afterwards.
693 * We must do one of several things here:
695 * a) Call scsi_end_request. This will finish off the
696 * specified number of sectors. If we are done, the
697 * command block will be released, and the queue
698 * function will be goosed. If we are not done, then
699 * scsi_end_request will directly goose the queue.
701 * b) We can just use scsi_requeue_command() here. This would
702 * be used if we just wanted to retry, for example.
704 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
705 unsigned int block_bytes)
707 int result = cmd->result;
708 int this_count = cmd->bufflen;
709 request_queue_t *q = cmd->device->request_queue;
710 struct request *req = cmd->request;
711 int clear_errors = 1;
712 struct scsi_sense_hdr sshdr;
714 int sense_deferred = 0;
716 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
720 * Free up any indirection buffers we allocated for DMA purposes.
721 * For the case of a READ, we need to copy the data out of the
722 * bounce buffer and into the real buffer.
725 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
726 else if (cmd->buffer != req->buffer) {
727 if (rq_data_dir(req) == READ) {
729 char *to = bio_kmap_irq(req->bio, &flags);
730 memcpy(to, cmd->buffer, cmd->bufflen);
731 bio_kunmap_irq(to, &flags);
737 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
739 sense_deferred = scsi_sense_is_deferred(&sshdr);
741 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
742 req->errors = result;
745 if (sense_valid && req->sense) {
747 * SG_IO wants current and deferred errors
749 int len = 8 + cmd->sense_buffer[7];
751 if (len > SCSI_SENSE_BUFFERSIZE)
752 len = SCSI_SENSE_BUFFERSIZE;
753 memcpy(req->sense, cmd->sense_buffer, len);
754 req->sense_len = len;
757 req->data_len = cmd->resid;
761 * Zero these out. They now point to freed memory, and it is
762 * dangerous to hang onto the pointers.
766 cmd->request_buffer = NULL;
767 cmd->request_bufflen = 0;
770 * Next deal with any sectors which we were able to correctly
773 if (good_bytes >= 0) {
774 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
775 req->nr_sectors, good_bytes));
776 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
781 * If multiple sectors are requested in one buffer, then
782 * they will have been finished off by the first command.
783 * If not, then we have a multi-buffer command.
785 * If block_bytes != 0, it means we had a medium error
786 * of some sort, and that we want to mark some number of
787 * sectors as not uptodate. Thus we want to inhibit
788 * requeueing right here - we will requeue down below
789 * when we handle the bad sectors.
791 cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
794 * If the command completed without error, then either finish off the
795 * rest of the command, or start a new one.
797 if (result == 0 || cmd == NULL ) {
802 * Now, if we were good little boys and girls, Santa left us a request
803 * sense buffer. We can extract information from this, so we
804 * can choose a block to remap, etc.
806 if (sense_valid && !sense_deferred) {
807 switch (sshdr.sense_key) {
809 if (cmd->device->removable) {
810 /* detected disc change. set a bit
811 * and quietly refuse further access.
813 cmd->device->changed = 1;
814 cmd = scsi_end_request(cmd, 0,
819 * Must have been a power glitch, or a
820 * bus reset. Could not have been a
821 * media change, so we just retry the
822 * request and see what happens.
824 scsi_requeue_command(q, cmd);
828 case ILLEGAL_REQUEST:
830 * If we had an ILLEGAL REQUEST returned, then we may
831 * have performed an unsupported command. The only
832 * thing this should be would be a ten byte read where
833 * only a six byte read was supported. Also, on a
834 * system where READ CAPACITY failed, we may have read
835 * past the end of the disk.
837 if (cmd->device->use_10_for_rw &&
838 (cmd->cmnd[0] == READ_10 ||
839 cmd->cmnd[0] == WRITE_10)) {
840 cmd->device->use_10_for_rw = 0;
842 * This will cause a retry with a 6-byte
845 scsi_requeue_command(q, cmd);
848 cmd = scsi_end_request(cmd, 0, this_count, 1);
854 * If the device is in the process of becoming ready,
857 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
858 scsi_requeue_command(q, cmd);
861 printk(KERN_INFO "Device %s not ready.\n",
862 req->rq_disk ? req->rq_disk->disk_name : "");
863 cmd = scsi_end_request(cmd, 0, this_count, 1);
865 case VOLUME_OVERFLOW:
866 printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
867 cmd->device->host->host_no,
868 (int)cmd->device->channel,
869 (int)cmd->device->id, (int)cmd->device->lun);
870 __scsi_print_command(cmd->data_cmnd);
871 scsi_print_sense("", cmd);
872 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
877 } /* driver byte != 0 */
878 if (host_byte(result) == DID_RESET) {
880 * Third party bus reset or reset for error
881 * recovery reasons. Just retry the request
882 * and see what happens.
884 scsi_requeue_command(q, cmd);
888 printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
889 "= 0x%x\n", cmd->device->host->host_no,
890 cmd->device->channel,
892 cmd->device->lun, result);
894 if (driver_byte(result) & DRIVER_SENSE)
895 scsi_print_sense("", cmd);
897 * Mark a single buffer as not uptodate. Queue the remainder.
898 * We sometimes get this cruft in the event that a medium error
899 * isn't properly reported.
901 block_bytes = req->hard_cur_sectors << 9;
903 block_bytes = req->data_len;
904 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
907 EXPORT_SYMBOL(scsi_io_completion);
910 * Function: scsi_init_io()
912 * Purpose: SCSI I/O initialize function.
914 * Arguments: cmd - Command descriptor we wish to initialize
916 * Returns: 0 on success
917 * BLKPREP_DEFER if the failure is retryable
918 * BLKPREP_KILL if the failure is fatal
920 static int scsi_init_io(struct scsi_cmnd *cmd)
922 struct request *req = cmd->request;
923 struct scatterlist *sgpnt;
927 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
929 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
930 cmd->request_bufflen = req->data_len;
931 cmd->request_buffer = req->data;
932 req->buffer = req->data;
938 * we used to not use scatter-gather for single segment request,
939 * but now we do (it makes highmem I/O easier to support without
942 cmd->use_sg = req->nr_phys_segments;
945 * if sg table allocation fails, requeue request later.
947 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
948 if (unlikely(!sgpnt))
949 return BLKPREP_DEFER;
951 cmd->request_buffer = (char *) sgpnt;
952 cmd->request_bufflen = req->nr_sectors << 9;
953 if (blk_pc_request(req))
954 cmd->request_bufflen = req->data_len;
958 * Next, walk the list, and fill in the addresses and sizes of
961 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
964 * mapped well, send it off
966 if (likely(count <= cmd->use_sg)) {
971 printk(KERN_ERR "Incorrect number of segments after building list\n");
972 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
973 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
974 req->current_nr_sectors);
976 /* release the command and kill it */
977 scsi_release_buffers(cmd);
978 scsi_put_command(cmd);
982 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
984 struct scsi_device *sdev = q->queuedata;
985 struct scsi_driver *drv;
987 if (sdev->sdev_state == SDEV_RUNNING) {
988 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
990 if (drv->prepare_flush)
991 return drv->prepare_flush(q, rq);
997 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
999 struct scsi_device *sdev = q->queuedata;
1000 struct request *flush_rq = rq->end_io_data;
1001 struct scsi_driver *drv;
1003 if (flush_rq->errors) {
1004 printk("scsi: barrier error, disabling flush support\n");
1005 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1008 if (sdev->sdev_state == SDEV_RUNNING) {
1009 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1010 drv->end_flush(q, rq);
1014 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1015 sector_t *error_sector)
1017 struct scsi_device *sdev = q->queuedata;
1018 struct scsi_driver *drv;
1020 if (sdev->sdev_state != SDEV_RUNNING)
1023 drv = *(struct scsi_driver **) disk->private_data;
1024 if (drv->issue_flush)
1025 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1030 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1032 struct scsi_device *sdev = q->queuedata;
1033 struct scsi_cmnd *cmd;
1034 int specials_only = 0;
1037 * Just check to see if the device is online. If it isn't, we
1038 * refuse to process any commands. The device must be brought
1039 * online before trying any recovery commands
1041 if (unlikely(!scsi_device_online(sdev))) {
1042 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1043 sdev->host->host_no, sdev->id, sdev->lun);
1044 return BLKPREP_KILL;
1046 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1047 /* OK, we're not in a running state don't prep
1049 if (sdev->sdev_state == SDEV_DEL) {
1050 /* Device is fully deleted, no commands
1051 * at all allowed down */
1052 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1053 sdev->host->host_no, sdev->id, sdev->lun);
1054 return BLKPREP_KILL;
1056 /* OK, we only allow special commands (i.e. not
1057 * user initiated ones */
1058 specials_only = sdev->sdev_state;
1062 * Find the actual device driver associated with this command.
1063 * The SPECIAL requests are things like character device or
1064 * ioctls, which did not originate from ll_rw_blk. Note that
1065 * the special field is also used to indicate the cmd for
1066 * the remainder of a partially fulfilled request that can
1067 * come up when there is a medium error. We have to treat
1068 * these two cases differently. We differentiate by looking
1069 * at request->cmd, as this tells us the real story.
1071 if (req->flags & REQ_SPECIAL) {
1072 struct scsi_request *sreq = req->special;
1074 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1075 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1078 scsi_init_cmd_from_req(cmd, sreq);
1081 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1083 if(unlikely(specials_only)) {
1084 if(specials_only == SDEV_QUIESCE ||
1085 specials_only == SDEV_BLOCK)
1086 return BLKPREP_DEFER;
1088 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1089 sdev->host->host_no, sdev->id, sdev->lun);
1090 return BLKPREP_KILL;
1095 * Now try and find a command block that we can use.
1097 if (!req->special) {
1098 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1104 /* pull a tag out of the request if we have one */
1105 cmd->tag = req->tag;
1107 blk_dump_rq_flags(req, "SCSI bad req");
1108 return BLKPREP_KILL;
1111 /* note the overloading of req->special. When the tag
1112 * is active it always means cmd. If the tag goes
1113 * back for re-queueing, it may be reset */
1118 * FIXME: drop the lock here because the functions below
1119 * expect to be called without the queue lock held. Also,
1120 * previously, we dequeued the request before dropping the
1121 * lock. We hope REQ_STARTED prevents anything untoward from
1124 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1125 struct scsi_driver *drv;
1129 * This will do a couple of things:
1130 * 1) Fill in the actual SCSI command.
1131 * 2) Fill in any other upper-level specific fields
1134 * If this returns 0, it means that the request failed
1135 * (reading past end of disk, reading offline device,
1136 * etc). This won't actually talk to the device, but
1137 * some kinds of consistency checking may cause the
1138 * request to be rejected immediately.
1142 * This sets up the scatter-gather table (allocating if
1145 ret = scsi_init_io(cmd);
1146 if (ret) /* BLKPREP_KILL return also releases the command */
1150 * Initialize the actual SCSI command for this request.
1152 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1153 if (unlikely(!drv->init_command(cmd))) {
1154 scsi_release_buffers(cmd);
1155 scsi_put_command(cmd);
1156 return BLKPREP_KILL;
1161 * The request is now prepped, no need to come back here
1163 req->flags |= REQ_DONTPREP;
1167 /* If we defer, the elv_next_request() returns NULL, but the
1168 * queue must be restarted, so we plug here if no returning
1169 * command will automatically do that. */
1170 if (sdev->device_busy == 0)
1172 return BLKPREP_DEFER;
1176 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1179 * Called with the queue_lock held.
1181 static inline int scsi_dev_queue_ready(struct request_queue *q,
1182 struct scsi_device *sdev)
1184 if (sdev->device_busy >= sdev->queue_depth)
1186 if (sdev->device_busy == 0 && sdev->device_blocked) {
1188 * unblock after device_blocked iterates to zero
1190 if (--sdev->device_blocked == 0) {
1192 printk("scsi%d (%d:%d) unblocking device at"
1193 " zero depth\n", sdev->host->host_no,
1194 sdev->id, sdev->lun));
1200 if (sdev->device_blocked)
1207 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1208 * return 0. We must end up running the queue again whenever 0 is
1209 * returned, else IO can hang.
1211 * Called with host_lock held.
1213 static inline int scsi_host_queue_ready(struct request_queue *q,
1214 struct Scsi_Host *shost,
1215 struct scsi_device *sdev)
1217 if (test_bit(SHOST_RECOVERY, &shost->shost_state))
1219 if (shost->host_busy == 0 && shost->host_blocked) {
1221 * unblock after host_blocked iterates to zero
1223 if (--shost->host_blocked == 0) {
1225 printk("scsi%d unblocking host at zero depth\n",
1232 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1233 shost->host_blocked || shost->host_self_blocked) {
1234 if (list_empty(&sdev->starved_entry))
1235 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1239 /* We're OK to process the command, so we can't be starved */
1240 if (!list_empty(&sdev->starved_entry))
1241 list_del_init(&sdev->starved_entry);
1247 * Kill requests for a dead device
1249 static void scsi_kill_requests(request_queue_t *q)
1251 struct request *req;
1253 while ((req = elv_next_request(q)) != NULL) {
1254 blkdev_dequeue_request(req);
1255 req->flags |= REQ_QUIET;
1256 while (end_that_request_first(req, 0, req->nr_sectors))
1258 end_that_request_last(req);
1263 * Function: scsi_request_fn()
1265 * Purpose: Main strategy routine for SCSI.
1267 * Arguments: q - Pointer to actual queue.
1271 * Lock status: IO request lock assumed to be held when called.
1273 static void scsi_request_fn(struct request_queue *q)
1275 struct scsi_device *sdev = q->queuedata;
1276 struct Scsi_Host *shost;
1277 struct scsi_cmnd *cmd;
1278 struct request *req;
1281 printk("scsi: killing requests for dead queue\n");
1282 scsi_kill_requests(q);
1286 if(!get_device(&sdev->sdev_gendev))
1287 /* We must be tearing the block queue down already */
1291 * To start with, we keep looping until the queue is empty, or until
1292 * the host is no longer able to accept any more requests.
1295 while (!blk_queue_plugged(q)) {
1298 * get next queueable request. We do this early to make sure
1299 * that the request is fully prepared even if we cannot
1302 req = elv_next_request(q);
1303 if (!req || !scsi_dev_queue_ready(q, sdev))
1306 if (unlikely(!scsi_device_online(sdev))) {
1307 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1308 sdev->host->host_no, sdev->id, sdev->lun);
1309 blkdev_dequeue_request(req);
1310 req->flags |= REQ_QUIET;
1311 while (end_that_request_first(req, 0, req->nr_sectors))
1313 end_that_request_last(req);
1319 * Remove the request from the request list.
1321 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1322 blkdev_dequeue_request(req);
1323 sdev->device_busy++;
1325 spin_unlock(q->queue_lock);
1326 spin_lock(shost->host_lock);
1328 if (!scsi_host_queue_ready(q, shost, sdev))
1330 if (sdev->single_lun) {
1331 if (scsi_target(sdev)->starget_sdev_user &&
1332 scsi_target(sdev)->starget_sdev_user != sdev)
1334 scsi_target(sdev)->starget_sdev_user = sdev;
1339 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1340 * take the lock again.
1342 spin_unlock_irq(shost->host_lock);
1345 if (unlikely(cmd == NULL)) {
1346 printk(KERN_CRIT "impossible request in %s.\n"
1347 "please mail a stack trace to "
1348 "linux-scsi@vger.kernel.org",
1354 * Finally, initialize any error handling parameters, and set up
1355 * the timers for timeouts.
1357 scsi_init_cmd_errh(cmd);
1360 * Dispatch the command to the low-level driver.
1362 rtn = scsi_dispatch_cmd(cmd);
1363 spin_lock_irq(q->queue_lock);
1365 /* we're refusing the command; because of
1366 * the way locks get dropped, we need to
1367 * check here if plugging is required */
1368 if(sdev->device_busy == 0)
1378 spin_unlock_irq(shost->host_lock);
1381 * lock q, handle tag, requeue req, and decrement device_busy. We
1382 * must return with queue_lock held.
1384 * Decrementing device_busy without checking it is OK, as all such
1385 * cases (host limits or settings) should run the queue at some
1388 spin_lock_irq(q->queue_lock);
1389 blk_requeue_request(q, req);
1390 sdev->device_busy--;
1391 if(sdev->device_busy == 0)
1394 /* must be careful here...if we trigger the ->remove() function
1395 * we cannot be holding the q lock */
1396 spin_unlock_irq(q->queue_lock);
1397 put_device(&sdev->sdev_gendev);
1398 spin_lock_irq(q->queue_lock);
1401 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1403 struct device *host_dev;
1404 u64 bounce_limit = 0xffffffff;
1406 if (shost->unchecked_isa_dma)
1407 return BLK_BOUNCE_ISA;
1409 * Platforms with virtual-DMA translation
1410 * hardware have no practical limit.
1412 if (!PCI_DMA_BUS_IS_PHYS)
1413 return BLK_BOUNCE_ANY;
1415 host_dev = scsi_get_device(shost);
1416 if (host_dev && host_dev->dma_mask)
1417 bounce_limit = *host_dev->dma_mask;
1419 return bounce_limit;
1421 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1423 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1425 struct Scsi_Host *shost = sdev->host;
1426 struct request_queue *q;
1428 q = blk_init_queue(scsi_request_fn, NULL);
1432 blk_queue_prep_rq(q, scsi_prep_fn);
1434 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1435 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1436 blk_queue_max_sectors(q, shost->max_sectors);
1437 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1438 blk_queue_segment_boundary(q, shost->dma_boundary);
1439 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1442 * ordered tags are superior to flush ordering
1444 if (shost->ordered_tag)
1445 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1446 else if (shost->ordered_flush) {
1447 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1448 q->prepare_flush_fn = scsi_prepare_flush_fn;
1449 q->end_flush_fn = scsi_end_flush_fn;
1452 if (!shost->use_clustering)
1453 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1457 void scsi_free_queue(struct request_queue *q)
1459 blk_cleanup_queue(q);
1463 * Function: scsi_block_requests()
1465 * Purpose: Utility function used by low-level drivers to prevent further
1466 * commands from being queued to the device.
1468 * Arguments: shost - Host in question
1472 * Lock status: No locks are assumed held.
1474 * Notes: There is no timer nor any other means by which the requests
1475 * get unblocked other than the low-level driver calling
1476 * scsi_unblock_requests().
1478 void scsi_block_requests(struct Scsi_Host *shost)
1480 shost->host_self_blocked = 1;
1482 EXPORT_SYMBOL(scsi_block_requests);
1485 * Function: scsi_unblock_requests()
1487 * Purpose: Utility function used by low-level drivers to allow further
1488 * commands from being queued to the device.
1490 * Arguments: shost - Host in question
1494 * Lock status: No locks are assumed held.
1496 * Notes: There is no timer nor any other means by which the requests
1497 * get unblocked other than the low-level driver calling
1498 * scsi_unblock_requests().
1500 * This is done as an API function so that changes to the
1501 * internals of the scsi mid-layer won't require wholesale
1502 * changes to drivers that use this feature.
1504 void scsi_unblock_requests(struct Scsi_Host *shost)
1506 shost->host_self_blocked = 0;
1507 scsi_run_host_queues(shost);
1509 EXPORT_SYMBOL(scsi_unblock_requests);
1511 int __init scsi_init_queue(void)
1515 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1516 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1517 int size = sgp->size * sizeof(struct scatterlist);
1519 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1520 SLAB_HWCACHE_ALIGN, NULL, NULL);
1522 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1526 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1527 mempool_alloc_slab, mempool_free_slab,
1530 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1538 void scsi_exit_queue(void)
1542 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1543 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1544 mempool_destroy(sgp->pool);
1545 kmem_cache_destroy(sgp->slab);
1549 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1550 * six bytes if necessary.
1551 * @sreq: SCSI request to fill in with the MODE_SENSE
1552 * @dbd: set if mode sense will allow block descriptors to be returned
1553 * @modepage: mode page being requested
1554 * @buffer: request buffer (may not be smaller than eight bytes)
1555 * @len: length of request buffer.
1556 * @timeout: command timeout
1557 * @retries: number of retries before failing
1558 * @data: returns a structure abstracting the mode header data
1560 * Returns zero if unsuccessful, or the header offset (either 4
1561 * or 8 depending on whether a six or ten byte command was
1562 * issued) if successful.
1565 __scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
1566 unsigned char *buffer, int len, int timeout, int retries,
1567 struct scsi_mode_data *data) {
1568 unsigned char cmd[12];
1572 memset(data, 0, sizeof(*data));
1573 memset(&cmd[0], 0, 12);
1574 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1578 use_10_for_ms = sreq->sr_device->use_10_for_ms;
1580 if (use_10_for_ms) {
1584 cmd[0] = MODE_SENSE_10;
1591 cmd[0] = MODE_SENSE;
1596 sreq->sr_cmd_len = 0;
1597 memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
1598 sreq->sr_data_direction = DMA_FROM_DEVICE;
1600 memset(buffer, 0, len);
1602 scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
1604 /* This code looks awful: what it's doing is making sure an
1605 * ILLEGAL REQUEST sense return identifies the actual command
1606 * byte as the problem. MODE_SENSE commands can return
1607 * ILLEGAL REQUEST if the code page isn't supported */
1609 if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
1610 (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
1611 struct scsi_sense_hdr sshdr;
1613 if (scsi_request_normalize_sense(sreq, &sshdr)) {
1614 if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
1615 (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
1617 * Invalid command operation code
1619 sreq->sr_device->use_10_for_ms = 0;
1625 if(scsi_status_is_good(sreq->sr_result)) {
1626 data->header_length = header_length;
1628 data->length = buffer[0]*256 + buffer[1] + 2;
1629 data->medium_type = buffer[2];
1630 data->device_specific = buffer[3];
1631 data->longlba = buffer[4] & 0x01;
1632 data->block_descriptor_length = buffer[6]*256
1635 data->length = buffer[0] + 1;
1636 data->medium_type = buffer[1];
1637 data->device_specific = buffer[2];
1638 data->block_descriptor_length = buffer[3];
1642 return sreq->sr_result;
1644 EXPORT_SYMBOL(__scsi_mode_sense);
1647 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1648 * six bytes if necessary.
1649 * @sdev: scsi device to send command to.
1650 * @dbd: set if mode sense will disable block descriptors in the return
1651 * @modepage: mode page being requested
1652 * @buffer: request buffer (may not be smaller than eight bytes)
1653 * @len: length of request buffer.
1654 * @timeout: command timeout
1655 * @retries: number of retries before failing
1657 * Returns zero if unsuccessful, or the header offset (either 4
1658 * or 8 depending on whether a six or ten byte command was
1659 * issued) if successful.
1662 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1663 unsigned char *buffer, int len, int timeout, int retries,
1664 struct scsi_mode_data *data)
1666 struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1672 ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
1673 timeout, retries, data);
1675 scsi_release_request(sreq);
1679 EXPORT_SYMBOL(scsi_mode_sense);
1682 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1684 struct scsi_request *sreq;
1686 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1690 sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1694 sreq->sr_data_direction = DMA_NONE;
1695 scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
1697 if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
1698 struct scsi_sense_hdr sshdr;
1700 if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
1701 ((sshdr.sense_key == UNIT_ATTENTION) ||
1702 (sshdr.sense_key == NOT_READY))) {
1704 sreq->sr_result = 0;
1707 result = sreq->sr_result;
1708 scsi_release_request(sreq);
1711 EXPORT_SYMBOL(scsi_test_unit_ready);
1714 * scsi_device_set_state - Take the given device through the device
1716 * @sdev: scsi device to change the state of.
1717 * @state: state to change to.
1719 * Returns zero if unsuccessful or an error if the requested
1720 * transition is illegal.
1723 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1725 enum scsi_device_state oldstate = sdev->sdev_state;
1727 if (state == oldstate)
1732 /* There are no legal states that come back to
1733 * created. This is the manually initialised start
1803 sdev->sdev_state = state;
1807 SCSI_LOG_ERROR_RECOVERY(1,
1808 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1809 "Illegal state transition %s->%s\n",
1810 scsi_device_state_name(oldstate),
1811 scsi_device_state_name(state))
1815 EXPORT_SYMBOL(scsi_device_set_state);
1818 * scsi_device_quiesce - Block user issued commands.
1819 * @sdev: scsi device to quiesce.
1821 * This works by trying to transition to the SDEV_QUIESCE state
1822 * (which must be a legal transition). When the device is in this
1823 * state, only special requests will be accepted, all others will
1824 * be deferred. Since special requests may also be requeued requests,
1825 * a successful return doesn't guarantee the device will be
1826 * totally quiescent.
1828 * Must be called with user context, may sleep.
1830 * Returns zero if unsuccessful or an error if not.
1833 scsi_device_quiesce(struct scsi_device *sdev)
1835 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1839 scsi_run_queue(sdev->request_queue);
1840 while (sdev->device_busy) {
1841 msleep_interruptible(200);
1842 scsi_run_queue(sdev->request_queue);
1846 EXPORT_SYMBOL(scsi_device_quiesce);
1849 * scsi_device_resume - Restart user issued commands to a quiesced device.
1850 * @sdev: scsi device to resume.
1852 * Moves the device from quiesced back to running and restarts the
1855 * Must be called with user context, may sleep.
1858 scsi_device_resume(struct scsi_device *sdev)
1860 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1862 scsi_run_queue(sdev->request_queue);
1864 EXPORT_SYMBOL(scsi_device_resume);
1867 device_quiesce_fn(struct scsi_device *sdev, void *data)
1869 scsi_device_quiesce(sdev);
1873 scsi_target_quiesce(struct scsi_target *starget)
1875 starget_for_each_device(starget, NULL, device_quiesce_fn);
1877 EXPORT_SYMBOL(scsi_target_quiesce);
1880 device_resume_fn(struct scsi_device *sdev, void *data)
1882 scsi_device_resume(sdev);
1886 scsi_target_resume(struct scsi_target *starget)
1888 starget_for_each_device(starget, NULL, device_resume_fn);
1890 EXPORT_SYMBOL(scsi_target_resume);
1893 * scsi_internal_device_block - internal function to put a device
1894 * temporarily into the SDEV_BLOCK state
1895 * @sdev: device to block
1897 * Block request made by scsi lld's to temporarily stop all
1898 * scsi commands on the specified device. Called from interrupt
1899 * or normal process context.
1901 * Returns zero if successful or error if not
1904 * This routine transitions the device to the SDEV_BLOCK state
1905 * (which must be a legal transition). When the device is in this
1906 * state, all commands are deferred until the scsi lld reenables
1907 * the device with scsi_device_unblock or device_block_tmo fires.
1908 * This routine assumes the host_lock is held on entry.
1911 scsi_internal_device_block(struct scsi_device *sdev)
1913 request_queue_t *q = sdev->request_queue;
1914 unsigned long flags;
1917 err = scsi_device_set_state(sdev, SDEV_BLOCK);
1922 * The device has transitioned to SDEV_BLOCK. Stop the
1923 * block layer from calling the midlayer with this device's
1926 spin_lock_irqsave(q->queue_lock, flags);
1928 spin_unlock_irqrestore(q->queue_lock, flags);
1932 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
1935 * scsi_internal_device_unblock - resume a device after a block request
1936 * @sdev: device to resume
1938 * Called by scsi lld's or the midlayer to restart the device queue
1939 * for the previously suspended scsi device. Called from interrupt or
1940 * normal process context.
1942 * Returns zero if successful or error if not.
1945 * This routine transitions the device to the SDEV_RUNNING state
1946 * (which must be a legal transition) allowing the midlayer to
1947 * goose the queue for this device. This routine assumes the
1948 * host_lock is held upon entry.
1951 scsi_internal_device_unblock(struct scsi_device *sdev)
1953 request_queue_t *q = sdev->request_queue;
1955 unsigned long flags;
1958 * Try to transition the scsi device to SDEV_RUNNING
1959 * and goose the device queue if successful.
1961 err = scsi_device_set_state(sdev, SDEV_RUNNING);
1965 spin_lock_irqsave(q->queue_lock, flags);
1967 spin_unlock_irqrestore(q->queue_lock, flags);
1971 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
1974 device_block(struct scsi_device *sdev, void *data)
1976 scsi_internal_device_block(sdev);
1980 target_block(struct device *dev, void *data)
1982 if (scsi_is_target_device(dev))
1983 starget_for_each_device(to_scsi_target(dev), NULL,
1989 scsi_target_block(struct device *dev)
1991 if (scsi_is_target_device(dev))
1992 starget_for_each_device(to_scsi_target(dev), NULL,
1995 device_for_each_child(dev, NULL, target_block);
1997 EXPORT_SYMBOL_GPL(scsi_target_block);
2000 device_unblock(struct scsi_device *sdev, void *data)
2002 scsi_internal_device_unblock(sdev);
2006 target_unblock(struct device *dev, void *data)
2008 if (scsi_is_target_device(dev))
2009 starget_for_each_device(to_scsi_target(dev), NULL,
2015 scsi_target_unblock(struct device *dev)
2017 if (scsi_is_target_device(dev))
2018 starget_for_each_device(to_scsi_target(dev), NULL,
2021 device_for_each_child(dev, NULL, target_unblock);
2023 EXPORT_SYMBOL_GPL(scsi_target_unblock);