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;
152 cmd->owner = SCSI_OWNER_MIDLEVEL;
155 * Decrement the counters, since these commands are no longer
156 * active on the host/device.
158 scsi_device_unbusy(device);
161 * Requeue this command. It will go before all other commands
162 * that are already in the queue.
164 * NOTE: there is magic here about the way the queue is plugged if
165 * we have no outstanding commands.
167 * Although we *don't* plug the queue, we call the request
168 * function. The SCSI request function detects the blocked condition
169 * and plugs the queue appropriately.
171 spin_lock_irqsave(q->queue_lock, flags);
172 blk_requeue_request(q, cmd->request);
173 spin_unlock_irqrestore(q->queue_lock, flags);
181 * Function: scsi_do_req
183 * Purpose: Queue a SCSI request
185 * Arguments: sreq - command descriptor.
186 * cmnd - actual SCSI command to be performed.
187 * buffer - data buffer.
188 * bufflen - size of data buffer.
189 * done - completion function to be run.
190 * timeout - how long to let it run before timeout.
191 * retries - number of retries we allow.
193 * Lock status: No locks held upon entry.
197 * Notes: This function is only used for queueing requests for things
198 * like ioctls and character device requests - this is because
199 * we essentially just inject a request into the queue for the
202 * In order to support the scsi_device_quiesce function, we
203 * now inject requests on the *head* of the device queue
204 * rather than the tail.
206 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
207 void *buffer, unsigned bufflen,
208 void (*done)(struct scsi_cmnd *),
209 int timeout, int retries)
212 * If the upper level driver is reusing these things, then
213 * we should release the low-level block now. Another one will
214 * be allocated later when this request is getting queued.
216 __scsi_release_request(sreq);
219 * Our own function scsi_done (which marks the host as not busy,
220 * disables the timeout counter, etc) will be called by us or by the
221 * scsi_hosts[host].queuecommand() function needs to also call
222 * the completion function for the high level driver.
224 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
225 sreq->sr_bufflen = bufflen;
226 sreq->sr_buffer = buffer;
227 sreq->sr_allowed = retries;
228 sreq->sr_done = done;
229 sreq->sr_timeout_per_command = timeout;
231 if (sreq->sr_cmd_len == 0)
232 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
235 * head injection *required* here otherwise quiesce won't work
237 scsi_insert_special_req(sreq, 1);
239 EXPORT_SYMBOL(scsi_do_req);
241 static void scsi_wait_done(struct scsi_cmnd *cmd)
243 struct request *req = cmd->request;
244 struct request_queue *q = cmd->device->request_queue;
247 req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
249 spin_lock_irqsave(q->queue_lock, flags);
250 if (blk_rq_tagged(req))
251 blk_queue_end_tag(q, req);
252 spin_unlock_irqrestore(q->queue_lock, flags);
255 complete(req->waiting);
258 /* This is the end routine we get to if a command was never attached
259 * to the request. Simply complete the request without changing
260 * rq_status; this will cause a DRIVER_ERROR. */
261 static void scsi_wait_req_end_io(struct request *req)
263 BUG_ON(!req->waiting);
265 complete(req->waiting);
268 void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
269 unsigned bufflen, int timeout, int retries)
271 DECLARE_COMPLETION(wait);
273 sreq->sr_request->waiting = &wait;
274 sreq->sr_request->rq_status = RQ_SCSI_BUSY;
275 sreq->sr_request->end_io = scsi_wait_req_end_io;
276 scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
278 wait_for_completion(&wait);
279 sreq->sr_request->waiting = NULL;
280 if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
281 sreq->sr_result |= (DRIVER_ERROR << 24);
283 __scsi_release_request(sreq);
285 EXPORT_SYMBOL(scsi_wait_req);
288 * Function: scsi_init_cmd_errh()
290 * Purpose: Initialize cmd fields related to error handling.
292 * Arguments: cmd - command that is ready to be queued.
296 * Notes: This function has the job of initializing a number of
297 * fields related to error handling. Typically this will
298 * be called once for each command, as required.
300 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
302 cmd->owner = SCSI_OWNER_MIDLEVEL;
303 cmd->serial_number = 0;
305 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
307 if (cmd->cmd_len == 0)
308 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
311 * We need saved copies of a number of fields - this is because
312 * error handling may need to overwrite these with different values
313 * to run different commands, and once error handling is complete,
314 * we will need to restore these values prior to running the actual
317 cmd->old_use_sg = cmd->use_sg;
318 cmd->old_cmd_len = cmd->cmd_len;
319 cmd->sc_old_data_direction = cmd->sc_data_direction;
320 cmd->old_underflow = cmd->underflow;
321 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
322 cmd->buffer = cmd->request_buffer;
323 cmd->bufflen = cmd->request_bufflen;
329 * Function: scsi_setup_cmd_retry()
331 * Purpose: Restore the command state for a retry
333 * Arguments: cmd - command to be restored
337 * Notes: Immediately prior to retrying a command, we need
338 * to restore certain fields that we saved above.
340 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
342 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
343 cmd->request_buffer = cmd->buffer;
344 cmd->request_bufflen = cmd->bufflen;
345 cmd->use_sg = cmd->old_use_sg;
346 cmd->cmd_len = cmd->old_cmd_len;
347 cmd->sc_data_direction = cmd->sc_old_data_direction;
348 cmd->underflow = cmd->old_underflow;
351 void scsi_device_unbusy(struct scsi_device *sdev)
353 struct Scsi_Host *shost = sdev->host;
356 spin_lock_irqsave(shost->host_lock, flags);
358 if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
360 scsi_eh_wakeup(shost);
361 spin_unlock(shost->host_lock);
362 spin_lock(sdev->request_queue->queue_lock);
364 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
368 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
369 * and call blk_run_queue for all the scsi_devices on the target -
370 * including current_sdev first.
372 * Called with *no* scsi locks held.
374 static void scsi_single_lun_run(struct scsi_device *current_sdev)
376 struct Scsi_Host *shost = current_sdev->host;
377 struct scsi_device *sdev, *tmp;
378 struct scsi_target *starget = scsi_target(current_sdev);
381 spin_lock_irqsave(shost->host_lock, flags);
382 starget->starget_sdev_user = NULL;
383 spin_unlock_irqrestore(shost->host_lock, flags);
386 * Call blk_run_queue for all LUNs on the target, starting with
387 * current_sdev. We race with others (to set starget_sdev_user),
388 * but in most cases, we will be first. Ideally, each LU on the
389 * target would get some limited time or requests on the target.
391 blk_run_queue(current_sdev->request_queue);
393 spin_lock_irqsave(shost->host_lock, flags);
394 if (starget->starget_sdev_user)
396 list_for_each_entry_safe(sdev, tmp, &starget->devices,
397 same_target_siblings) {
398 if (sdev == current_sdev)
400 if (scsi_device_get(sdev))
403 spin_unlock_irqrestore(shost->host_lock, flags);
404 blk_run_queue(sdev->request_queue);
405 spin_lock_irqsave(shost->host_lock, flags);
407 scsi_device_put(sdev);
410 spin_unlock_irqrestore(shost->host_lock, flags);
414 * Function: scsi_run_queue()
416 * Purpose: Select a proper request queue to serve next
418 * Arguments: q - last request's queue
422 * Notes: The previous command was completely finished, start
423 * a new one if possible.
425 static void scsi_run_queue(struct request_queue *q)
427 struct scsi_device *sdev = q->queuedata;
428 struct Scsi_Host *shost = sdev->host;
431 if (sdev->single_lun)
432 scsi_single_lun_run(sdev);
434 spin_lock_irqsave(shost->host_lock, flags);
435 while (!list_empty(&shost->starved_list) &&
436 !shost->host_blocked && !shost->host_self_blocked &&
437 !((shost->can_queue > 0) &&
438 (shost->host_busy >= shost->can_queue))) {
440 * As long as shost is accepting commands and we have
441 * starved queues, call blk_run_queue. scsi_request_fn
442 * drops the queue_lock and can add us back to the
445 * host_lock protects the starved_list and starved_entry.
446 * scsi_request_fn must get the host_lock before checking
447 * or modifying starved_list or starved_entry.
449 sdev = list_entry(shost->starved_list.next,
450 struct scsi_device, starved_entry);
451 list_del_init(&sdev->starved_entry);
452 spin_unlock_irqrestore(shost->host_lock, flags);
454 blk_run_queue(sdev->request_queue);
456 spin_lock_irqsave(shost->host_lock, flags);
457 if (unlikely(!list_empty(&sdev->starved_entry)))
459 * sdev lost a race, and was put back on the
460 * starved list. This is unlikely but without this
461 * in theory we could loop forever.
465 spin_unlock_irqrestore(shost->host_lock, flags);
471 * Function: scsi_requeue_command()
473 * Purpose: Handle post-processing of completed commands.
475 * Arguments: q - queue to operate on
476 * cmd - command that may need to be requeued.
480 * Notes: After command completion, there may be blocks left
481 * over which weren't finished by the previous command
482 * this can be for a number of reasons - the main one is
483 * I/O errors in the middle of the request, in which case
484 * we need to request the blocks that come after the bad
487 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
491 cmd->request->flags &= ~REQ_DONTPREP;
493 spin_lock_irqsave(q->queue_lock, flags);
494 blk_requeue_request(q, cmd->request);
495 spin_unlock_irqrestore(q->queue_lock, flags);
500 void scsi_next_command(struct scsi_cmnd *cmd)
502 struct request_queue *q = cmd->device->request_queue;
504 scsi_put_command(cmd);
508 void scsi_run_host_queues(struct Scsi_Host *shost)
510 struct scsi_device *sdev;
512 shost_for_each_device(sdev, shost)
513 scsi_run_queue(sdev->request_queue);
517 * Function: scsi_end_request()
519 * Purpose: Post-processing of completed commands (usually invoked at end
520 * of upper level post-processing and scsi_io_completion).
522 * Arguments: cmd - command that is complete.
523 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
524 * bytes - number of bytes of completed I/O
525 * requeue - indicates whether we should requeue leftovers.
527 * Lock status: Assumed that lock is not held upon entry.
529 * Returns: cmd if requeue done or required, NULL otherwise
531 * Notes: This is called for block device requests in order to
532 * mark some number of sectors as complete.
534 * We are guaranteeing that the request queue will be goosed
535 * at some point during this call.
537 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
538 int bytes, int requeue)
540 request_queue_t *q = cmd->device->request_queue;
541 struct request *req = cmd->request;
545 * If there are blocks left over at the end, set up the command
546 * to queue the remainder of them.
548 if (end_that_request_chunk(req, uptodate, bytes)) {
549 int leftover = (req->hard_nr_sectors << 9);
551 if (blk_pc_request(req))
552 leftover = req->data_len;
554 /* kill remainder if no retrys */
555 if (!uptodate && blk_noretry_request(req))
556 end_that_request_chunk(req, 0, leftover);
560 * Bleah. Leftovers again. Stick the
561 * leftovers in the front of the
562 * queue, and goose the queue again.
564 scsi_requeue_command(q, cmd);
570 add_disk_randomness(req->rq_disk);
572 spin_lock_irqsave(q->queue_lock, flags);
573 if (blk_rq_tagged(req))
574 blk_queue_end_tag(q, req);
575 end_that_request_last(req);
576 spin_unlock_irqrestore(q->queue_lock, flags);
579 * This will goose the queue request function at the end, so we don't
580 * need to worry about launching another command.
582 scsi_next_command(cmd);
586 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
588 struct scsi_host_sg_pool *sgp;
589 struct scatterlist *sgl;
591 BUG_ON(!cmd->use_sg);
593 switch (cmd->use_sg) {
603 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
607 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
611 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
622 sgp = scsi_sg_pools + cmd->sglist_len;
623 sgl = mempool_alloc(sgp->pool, gfp_mask);
625 memset(sgl, 0, sgp->size);
629 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
631 struct scsi_host_sg_pool *sgp;
633 BUG_ON(index > SG_MEMPOOL_NR);
635 sgp = scsi_sg_pools + index;
636 mempool_free(sgl, sgp->pool);
640 * Function: scsi_release_buffers()
642 * Purpose: Completion processing for block device I/O requests.
644 * Arguments: cmd - command that we are bailing.
646 * Lock status: Assumed that no lock is held upon entry.
650 * Notes: In the event that an upper level driver rejects a
651 * command, we must release resources allocated during
652 * the __init_io() function. Primarily this would involve
653 * the scatter-gather table, and potentially any bounce
656 static void scsi_release_buffers(struct scsi_cmnd *cmd)
658 struct request *req = cmd->request;
661 * Free up any indirection buffers we allocated for DMA purposes.
664 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
665 else if (cmd->request_buffer != req->buffer)
666 kfree(cmd->request_buffer);
669 * Zero these out. They now point to freed memory, and it is
670 * dangerous to hang onto the pointers.
674 cmd->request_buffer = NULL;
675 cmd->request_bufflen = 0;
679 * Function: scsi_io_completion()
681 * Purpose: Completion processing for block device I/O requests.
683 * Arguments: cmd - command that is finished.
685 * Lock status: Assumed that no lock is held upon entry.
689 * Notes: This function is matched in terms of capabilities to
690 * the function that created the scatter-gather list.
691 * In other words, if there are no bounce buffers
692 * (the normal case for most drivers), we don't need
693 * the logic to deal with cleaning up afterwards.
695 * We must do one of several things here:
697 * a) Call scsi_end_request. This will finish off the
698 * specified number of sectors. If we are done, the
699 * command block will be released, and the queue
700 * function will be goosed. If we are not done, then
701 * scsi_end_request will directly goose the queue.
703 * b) We can just use scsi_requeue_command() here. This would
704 * be used if we just wanted to retry, for example.
706 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
707 unsigned int block_bytes)
709 int result = cmd->result;
710 int this_count = cmd->bufflen;
711 request_queue_t *q = cmd->device->request_queue;
712 struct request *req = cmd->request;
713 int clear_errors = 1;
714 struct scsi_sense_hdr sshdr;
716 int sense_deferred = 0;
718 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
722 * Free up any indirection buffers we allocated for DMA purposes.
723 * For the case of a READ, we need to copy the data out of the
724 * bounce buffer and into the real buffer.
727 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
728 else if (cmd->buffer != req->buffer) {
729 if (rq_data_dir(req) == READ) {
731 char *to = bio_kmap_irq(req->bio, &flags);
732 memcpy(to, cmd->buffer, cmd->bufflen);
733 bio_kunmap_irq(to, &flags);
739 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
741 sense_deferred = scsi_sense_is_deferred(&sshdr);
743 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
744 req->errors = result;
747 if (sense_valid && req->sense) {
749 * SG_IO wants current and deferred errors
751 int len = 8 + cmd->sense_buffer[7];
753 if (len > SCSI_SENSE_BUFFERSIZE)
754 len = SCSI_SENSE_BUFFERSIZE;
755 memcpy(req->sense, cmd->sense_buffer, len);
756 req->sense_len = len;
759 req->data_len = cmd->resid;
763 * Zero these out. They now point to freed memory, and it is
764 * dangerous to hang onto the pointers.
768 cmd->request_buffer = NULL;
769 cmd->request_bufflen = 0;
772 * Next deal with any sectors which we were able to correctly
775 if (good_bytes >= 0) {
776 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
777 req->nr_sectors, good_bytes));
778 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
783 * If multiple sectors are requested in one buffer, then
784 * they will have been finished off by the first command.
785 * If not, then we have a multi-buffer command.
787 * If block_bytes != 0, it means we had a medium error
788 * of some sort, and that we want to mark some number of
789 * sectors as not uptodate. Thus we want to inhibit
790 * requeueing right here - we will requeue down below
791 * when we handle the bad sectors.
793 cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
796 * If the command completed without error, then either finish off the
797 * rest of the command, or start a new one.
799 if (result == 0 || cmd == NULL ) {
804 * Now, if we were good little boys and girls, Santa left us a request
805 * sense buffer. We can extract information from this, so we
806 * can choose a block to remap, etc.
808 if (sense_valid && !sense_deferred) {
809 switch (sshdr.sense_key) {
811 if (cmd->device->removable) {
812 /* detected disc change. set a bit
813 * and quietly refuse further access.
815 cmd->device->changed = 1;
816 cmd = scsi_end_request(cmd, 0,
821 * Must have been a power glitch, or a
822 * bus reset. Could not have been a
823 * media change, so we just retry the
824 * request and see what happens.
826 scsi_requeue_command(q, cmd);
830 case ILLEGAL_REQUEST:
832 * If we had an ILLEGAL REQUEST returned, then we may
833 * have performed an unsupported command. The only
834 * thing this should be would be a ten byte read where
835 * only a six byte read was supported. Also, on a
836 * system where READ CAPACITY failed, we may have read
837 * past the end of the disk.
839 if (cmd->device->use_10_for_rw &&
840 (cmd->cmnd[0] == READ_10 ||
841 cmd->cmnd[0] == WRITE_10)) {
842 cmd->device->use_10_for_rw = 0;
844 * This will cause a retry with a 6-byte
847 scsi_requeue_command(q, cmd);
850 cmd = scsi_end_request(cmd, 0, this_count, 1);
856 * If the device is in the process of becoming ready,
859 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
860 scsi_requeue_command(q, cmd);
863 printk(KERN_INFO "Device %s not ready.\n",
864 req->rq_disk ? req->rq_disk->disk_name : "");
865 cmd = scsi_end_request(cmd, 0, this_count, 1);
867 case VOLUME_OVERFLOW:
868 printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
869 cmd->device->host->host_no,
870 (int)cmd->device->channel,
871 (int)cmd->device->id, (int)cmd->device->lun);
872 __scsi_print_command(cmd->data_cmnd);
873 scsi_print_sense("", cmd);
874 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
879 } /* driver byte != 0 */
880 if (host_byte(result) == DID_RESET) {
882 * Third party bus reset or reset for error
883 * recovery reasons. Just retry the request
884 * and see what happens.
886 scsi_requeue_command(q, cmd);
890 printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
891 "= 0x%x\n", cmd->device->host->host_no,
892 cmd->device->channel,
894 cmd->device->lun, result);
896 if (driver_byte(result) & DRIVER_SENSE)
897 scsi_print_sense("", cmd);
899 * Mark a single buffer as not uptodate. Queue the remainder.
900 * We sometimes get this cruft in the event that a medium error
901 * isn't properly reported.
903 block_bytes = req->hard_cur_sectors << 9;
905 block_bytes = req->data_len;
906 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
909 EXPORT_SYMBOL(scsi_io_completion);
912 * Function: scsi_init_io()
914 * Purpose: SCSI I/O initialize function.
916 * Arguments: cmd - Command descriptor we wish to initialize
918 * Returns: 0 on success
919 * BLKPREP_DEFER if the failure is retryable
920 * BLKPREP_KILL if the failure is fatal
922 static int scsi_init_io(struct scsi_cmnd *cmd)
924 struct request *req = cmd->request;
925 struct scatterlist *sgpnt;
929 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
931 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
932 cmd->request_bufflen = req->data_len;
933 cmd->request_buffer = req->data;
934 req->buffer = req->data;
940 * we used to not use scatter-gather for single segment request,
941 * but now we do (it makes highmem I/O easier to support without
944 cmd->use_sg = req->nr_phys_segments;
947 * if sg table allocation fails, requeue request later.
949 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
950 if (unlikely(!sgpnt))
951 return BLKPREP_DEFER;
953 cmd->request_buffer = (char *) sgpnt;
954 cmd->request_bufflen = req->nr_sectors << 9;
955 if (blk_pc_request(req))
956 cmd->request_bufflen = req->data_len;
960 * Next, walk the list, and fill in the addresses and sizes of
963 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
966 * mapped well, send it off
968 if (likely(count <= cmd->use_sg)) {
973 printk(KERN_ERR "Incorrect number of segments after building list\n");
974 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
975 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
976 req->current_nr_sectors);
978 /* release the command and kill it */
979 scsi_release_buffers(cmd);
980 scsi_put_command(cmd);
984 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
986 struct scsi_device *sdev = q->queuedata;
987 struct scsi_driver *drv;
989 if (sdev->sdev_state == SDEV_RUNNING) {
990 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
992 if (drv->prepare_flush)
993 return drv->prepare_flush(q, rq);
999 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
1001 struct scsi_device *sdev = q->queuedata;
1002 struct request *flush_rq = rq->end_io_data;
1003 struct scsi_driver *drv;
1005 if (flush_rq->errors) {
1006 printk("scsi: barrier error, disabling flush support\n");
1007 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1010 if (sdev->sdev_state == SDEV_RUNNING) {
1011 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1012 drv->end_flush(q, rq);
1016 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1017 sector_t *error_sector)
1019 struct scsi_device *sdev = q->queuedata;
1020 struct scsi_driver *drv;
1022 if (sdev->sdev_state != SDEV_RUNNING)
1025 drv = *(struct scsi_driver **) disk->private_data;
1026 if (drv->issue_flush)
1027 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1032 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1034 struct scsi_device *sdev = q->queuedata;
1035 struct scsi_cmnd *cmd;
1036 int specials_only = 0;
1039 * Just check to see if the device is online. If it isn't, we
1040 * refuse to process any commands. The device must be brought
1041 * online before trying any recovery commands
1043 if (unlikely(!scsi_device_online(sdev))) {
1044 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1045 sdev->host->host_no, sdev->id, sdev->lun);
1046 return BLKPREP_KILL;
1048 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1049 /* OK, we're not in a running state don't prep
1051 if (sdev->sdev_state == SDEV_DEL) {
1052 /* Device is fully deleted, no commands
1053 * at all allowed down */
1054 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1055 sdev->host->host_no, sdev->id, sdev->lun);
1056 return BLKPREP_KILL;
1058 /* OK, we only allow special commands (i.e. not
1059 * user initiated ones */
1060 specials_only = sdev->sdev_state;
1064 * Find the actual device driver associated with this command.
1065 * The SPECIAL requests are things like character device or
1066 * ioctls, which did not originate from ll_rw_blk. Note that
1067 * the special field is also used to indicate the cmd for
1068 * the remainder of a partially fulfilled request that can
1069 * come up when there is a medium error. We have to treat
1070 * these two cases differently. We differentiate by looking
1071 * at request->cmd, as this tells us the real story.
1073 if (req->flags & REQ_SPECIAL) {
1074 struct scsi_request *sreq = req->special;
1076 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1077 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1080 scsi_init_cmd_from_req(cmd, sreq);
1083 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1085 if(unlikely(specials_only)) {
1086 if(specials_only == SDEV_QUIESCE ||
1087 specials_only == SDEV_BLOCK)
1088 return BLKPREP_DEFER;
1090 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1091 sdev->host->host_no, sdev->id, sdev->lun);
1092 return BLKPREP_KILL;
1097 * Now try and find a command block that we can use.
1099 if (!req->special) {
1100 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1106 /* pull a tag out of the request if we have one */
1107 cmd->tag = req->tag;
1109 blk_dump_rq_flags(req, "SCSI bad req");
1110 return BLKPREP_KILL;
1113 /* note the overloading of req->special. When the tag
1114 * is active it always means cmd. If the tag goes
1115 * back for re-queueing, it may be reset */
1120 * FIXME: drop the lock here because the functions below
1121 * expect to be called without the queue lock held. Also,
1122 * previously, we dequeued the request before dropping the
1123 * lock. We hope REQ_STARTED prevents anything untoward from
1126 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1127 struct scsi_driver *drv;
1131 * This will do a couple of things:
1132 * 1) Fill in the actual SCSI command.
1133 * 2) Fill in any other upper-level specific fields
1136 * If this returns 0, it means that the request failed
1137 * (reading past end of disk, reading offline device,
1138 * etc). This won't actually talk to the device, but
1139 * some kinds of consistency checking may cause the
1140 * request to be rejected immediately.
1144 * This sets up the scatter-gather table (allocating if
1147 ret = scsi_init_io(cmd);
1148 if (ret) /* BLKPREP_KILL return also releases the command */
1152 * Initialize the actual SCSI command for this request.
1154 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1155 if (unlikely(!drv->init_command(cmd))) {
1156 scsi_release_buffers(cmd);
1157 scsi_put_command(cmd);
1158 return BLKPREP_KILL;
1163 * The request is now prepped, no need to come back here
1165 req->flags |= REQ_DONTPREP;
1169 /* If we defer, the elv_next_request() returns NULL, but the
1170 * queue must be restarted, so we plug here if no returning
1171 * command will automatically do that. */
1172 if (sdev->device_busy == 0)
1174 return BLKPREP_DEFER;
1178 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1181 * Called with the queue_lock held.
1183 static inline int scsi_dev_queue_ready(struct request_queue *q,
1184 struct scsi_device *sdev)
1186 if (sdev->device_busy >= sdev->queue_depth)
1188 if (sdev->device_busy == 0 && sdev->device_blocked) {
1190 * unblock after device_blocked iterates to zero
1192 if (--sdev->device_blocked == 0) {
1194 printk("scsi%d (%d:%d) unblocking device at"
1195 " zero depth\n", sdev->host->host_no,
1196 sdev->id, sdev->lun));
1202 if (sdev->device_blocked)
1209 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1210 * return 0. We must end up running the queue again whenever 0 is
1211 * returned, else IO can hang.
1213 * Called with host_lock held.
1215 static inline int scsi_host_queue_ready(struct request_queue *q,
1216 struct Scsi_Host *shost,
1217 struct scsi_device *sdev)
1219 if (test_bit(SHOST_RECOVERY, &shost->shost_state))
1221 if (shost->host_busy == 0 && shost->host_blocked) {
1223 * unblock after host_blocked iterates to zero
1225 if (--shost->host_blocked == 0) {
1227 printk("scsi%d unblocking host at zero depth\n",
1234 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1235 shost->host_blocked || shost->host_self_blocked) {
1236 if (list_empty(&sdev->starved_entry))
1237 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1241 /* We're OK to process the command, so we can't be starved */
1242 if (!list_empty(&sdev->starved_entry))
1243 list_del_init(&sdev->starved_entry);
1249 * Kill requests for a dead device
1251 static void scsi_kill_requests(request_queue_t *q)
1253 struct request *req;
1255 while ((req = elv_next_request(q)) != NULL) {
1256 blkdev_dequeue_request(req);
1257 req->flags |= REQ_QUIET;
1258 while (end_that_request_first(req, 0, req->nr_sectors))
1260 end_that_request_last(req);
1265 * Function: scsi_request_fn()
1267 * Purpose: Main strategy routine for SCSI.
1269 * Arguments: q - Pointer to actual queue.
1273 * Lock status: IO request lock assumed to be held when called.
1275 static void scsi_request_fn(struct request_queue *q)
1277 struct scsi_device *sdev = q->queuedata;
1278 struct Scsi_Host *shost;
1279 struct scsi_cmnd *cmd;
1280 struct request *req;
1283 printk("scsi: killing requests for dead queue\n");
1284 scsi_kill_requests(q);
1288 if(!get_device(&sdev->sdev_gendev))
1289 /* We must be tearing the block queue down already */
1293 * To start with, we keep looping until the queue is empty, or until
1294 * the host is no longer able to accept any more requests.
1297 while (!blk_queue_plugged(q)) {
1300 * get next queueable request. We do this early to make sure
1301 * that the request is fully prepared even if we cannot
1304 req = elv_next_request(q);
1305 if (!req || !scsi_dev_queue_ready(q, sdev))
1308 if (unlikely(!scsi_device_online(sdev))) {
1309 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1310 sdev->host->host_no, sdev->id, sdev->lun);
1311 blkdev_dequeue_request(req);
1312 req->flags |= REQ_QUIET;
1313 while (end_that_request_first(req, 0, req->nr_sectors))
1315 end_that_request_last(req);
1321 * Remove the request from the request list.
1323 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1324 blkdev_dequeue_request(req);
1325 sdev->device_busy++;
1327 spin_unlock(q->queue_lock);
1328 spin_lock(shost->host_lock);
1330 if (!scsi_host_queue_ready(q, shost, sdev))
1332 if (sdev->single_lun) {
1333 if (scsi_target(sdev)->starget_sdev_user &&
1334 scsi_target(sdev)->starget_sdev_user != sdev)
1336 scsi_target(sdev)->starget_sdev_user = sdev;
1341 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1342 * take the lock again.
1344 spin_unlock_irq(shost->host_lock);
1347 if (unlikely(cmd == NULL)) {
1348 printk(KERN_CRIT "impossible request in %s.\n"
1349 "please mail a stack trace to "
1350 "linux-scsi@vger.kernel.org",
1356 * Finally, initialize any error handling parameters, and set up
1357 * the timers for timeouts.
1359 scsi_init_cmd_errh(cmd);
1362 * Dispatch the command to the low-level driver.
1364 rtn = scsi_dispatch_cmd(cmd);
1365 spin_lock_irq(q->queue_lock);
1367 /* we're refusing the command; because of
1368 * the way locks get dropped, we need to
1369 * check here if plugging is required */
1370 if(sdev->device_busy == 0)
1380 spin_unlock_irq(shost->host_lock);
1383 * lock q, handle tag, requeue req, and decrement device_busy. We
1384 * must return with queue_lock held.
1386 * Decrementing device_busy without checking it is OK, as all such
1387 * cases (host limits or settings) should run the queue at some
1390 spin_lock_irq(q->queue_lock);
1391 blk_requeue_request(q, req);
1392 sdev->device_busy--;
1393 if(sdev->device_busy == 0)
1396 /* must be careful here...if we trigger the ->remove() function
1397 * we cannot be holding the q lock */
1398 spin_unlock_irq(q->queue_lock);
1399 put_device(&sdev->sdev_gendev);
1400 spin_lock_irq(q->queue_lock);
1403 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1405 struct device *host_dev;
1406 u64 bounce_limit = 0xffffffff;
1408 if (shost->unchecked_isa_dma)
1409 return BLK_BOUNCE_ISA;
1411 * Platforms with virtual-DMA translation
1412 * hardware have no practical limit.
1414 if (!PCI_DMA_BUS_IS_PHYS)
1415 return BLK_BOUNCE_ANY;
1417 host_dev = scsi_get_device(shost);
1418 if (host_dev && host_dev->dma_mask)
1419 bounce_limit = *host_dev->dma_mask;
1421 return bounce_limit;
1423 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1425 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1427 struct Scsi_Host *shost = sdev->host;
1428 struct request_queue *q;
1430 q = blk_init_queue(scsi_request_fn, NULL);
1434 blk_queue_prep_rq(q, scsi_prep_fn);
1436 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1437 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1438 blk_queue_max_sectors(q, shost->max_sectors);
1439 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1440 blk_queue_segment_boundary(q, shost->dma_boundary);
1441 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1444 * ordered tags are superior to flush ordering
1446 if (shost->ordered_tag)
1447 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1448 else if (shost->ordered_flush) {
1449 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1450 q->prepare_flush_fn = scsi_prepare_flush_fn;
1451 q->end_flush_fn = scsi_end_flush_fn;
1454 if (!shost->use_clustering)
1455 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1459 void scsi_free_queue(struct request_queue *q)
1461 blk_cleanup_queue(q);
1465 * Function: scsi_block_requests()
1467 * Purpose: Utility function used by low-level drivers to prevent further
1468 * commands from being queued to the device.
1470 * Arguments: shost - Host in question
1474 * Lock status: No locks are assumed held.
1476 * Notes: There is no timer nor any other means by which the requests
1477 * get unblocked other than the low-level driver calling
1478 * scsi_unblock_requests().
1480 void scsi_block_requests(struct Scsi_Host *shost)
1482 shost->host_self_blocked = 1;
1484 EXPORT_SYMBOL(scsi_block_requests);
1487 * Function: scsi_unblock_requests()
1489 * Purpose: Utility function used by low-level drivers to allow further
1490 * commands from being queued to the device.
1492 * Arguments: shost - Host in question
1496 * Lock status: No locks are assumed held.
1498 * Notes: There is no timer nor any other means by which the requests
1499 * get unblocked other than the low-level driver calling
1500 * scsi_unblock_requests().
1502 * This is done as an API function so that changes to the
1503 * internals of the scsi mid-layer won't require wholesale
1504 * changes to drivers that use this feature.
1506 void scsi_unblock_requests(struct Scsi_Host *shost)
1508 shost->host_self_blocked = 0;
1509 scsi_run_host_queues(shost);
1511 EXPORT_SYMBOL(scsi_unblock_requests);
1513 int __init scsi_init_queue(void)
1517 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1518 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1519 int size = sgp->size * sizeof(struct scatterlist);
1521 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1522 SLAB_HWCACHE_ALIGN, NULL, NULL);
1524 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1528 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1529 mempool_alloc_slab, mempool_free_slab,
1532 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1540 void scsi_exit_queue(void)
1544 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1545 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1546 mempool_destroy(sgp->pool);
1547 kmem_cache_destroy(sgp->slab);
1551 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1552 * six bytes if necessary.
1553 * @sreq: SCSI request to fill in with the MODE_SENSE
1554 * @dbd: set if mode sense will allow block descriptors to be returned
1555 * @modepage: mode page being requested
1556 * @buffer: request buffer (may not be smaller than eight bytes)
1557 * @len: length of request buffer.
1558 * @timeout: command timeout
1559 * @retries: number of retries before failing
1560 * @data: returns a structure abstracting the mode header data
1562 * Returns zero if unsuccessful, or the header offset (either 4
1563 * or 8 depending on whether a six or ten byte command was
1564 * issued) if successful.
1567 __scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
1568 unsigned char *buffer, int len, int timeout, int retries,
1569 struct scsi_mode_data *data) {
1570 unsigned char cmd[12];
1574 memset(data, 0, sizeof(*data));
1575 memset(&cmd[0], 0, 12);
1576 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1580 use_10_for_ms = sreq->sr_device->use_10_for_ms;
1582 if (use_10_for_ms) {
1586 cmd[0] = MODE_SENSE_10;
1593 cmd[0] = MODE_SENSE;
1598 sreq->sr_cmd_len = 0;
1599 memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
1600 sreq->sr_data_direction = DMA_FROM_DEVICE;
1602 memset(buffer, 0, len);
1604 scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
1606 /* This code looks awful: what it's doing is making sure an
1607 * ILLEGAL REQUEST sense return identifies the actual command
1608 * byte as the problem. MODE_SENSE commands can return
1609 * ILLEGAL REQUEST if the code page isn't supported */
1611 if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
1612 (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
1613 struct scsi_sense_hdr sshdr;
1615 if (scsi_request_normalize_sense(sreq, &sshdr)) {
1616 if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
1617 (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
1619 * Invalid command operation code
1621 sreq->sr_device->use_10_for_ms = 0;
1627 if(scsi_status_is_good(sreq->sr_result)) {
1628 data->header_length = header_length;
1630 data->length = buffer[0]*256 + buffer[1] + 2;
1631 data->medium_type = buffer[2];
1632 data->device_specific = buffer[3];
1633 data->longlba = buffer[4] & 0x01;
1634 data->block_descriptor_length = buffer[6]*256
1637 data->length = buffer[0] + 1;
1638 data->medium_type = buffer[1];
1639 data->device_specific = buffer[2];
1640 data->block_descriptor_length = buffer[3];
1644 return sreq->sr_result;
1646 EXPORT_SYMBOL(__scsi_mode_sense);
1649 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1650 * six bytes if necessary.
1651 * @sdev: scsi device to send command to.
1652 * @dbd: set if mode sense will disable block descriptors in the return
1653 * @modepage: mode page being requested
1654 * @buffer: request buffer (may not be smaller than eight bytes)
1655 * @len: length of request buffer.
1656 * @timeout: command timeout
1657 * @retries: number of retries before failing
1659 * Returns zero if unsuccessful, or the header offset (either 4
1660 * or 8 depending on whether a six or ten byte command was
1661 * issued) if successful.
1664 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1665 unsigned char *buffer, int len, int timeout, int retries,
1666 struct scsi_mode_data *data)
1668 struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1674 ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
1675 timeout, retries, data);
1677 scsi_release_request(sreq);
1681 EXPORT_SYMBOL(scsi_mode_sense);
1684 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1686 struct scsi_request *sreq;
1688 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1692 sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1696 sreq->sr_data_direction = DMA_NONE;
1697 scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
1699 if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
1700 struct scsi_sense_hdr sshdr;
1702 if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
1703 ((sshdr.sense_key == UNIT_ATTENTION) ||
1704 (sshdr.sense_key == NOT_READY))) {
1706 sreq->sr_result = 0;
1709 result = sreq->sr_result;
1710 scsi_release_request(sreq);
1713 EXPORT_SYMBOL(scsi_test_unit_ready);
1716 * scsi_device_set_state - Take the given device through the device
1718 * @sdev: scsi device to change the state of.
1719 * @state: state to change to.
1721 * Returns zero if unsuccessful or an error if the requested
1722 * transition is illegal.
1725 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1727 enum scsi_device_state oldstate = sdev->sdev_state;
1729 if (state == oldstate)
1734 /* There are no legal states that come back to
1735 * created. This is the manually initialised start
1805 sdev->sdev_state = state;
1809 SCSI_LOG_ERROR_RECOVERY(1,
1810 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1811 "Illegal state transition %s->%s\n",
1812 scsi_device_state_name(oldstate),
1813 scsi_device_state_name(state))
1817 EXPORT_SYMBOL(scsi_device_set_state);
1820 * scsi_device_quiesce - Block user issued commands.
1821 * @sdev: scsi device to quiesce.
1823 * This works by trying to transition to the SDEV_QUIESCE state
1824 * (which must be a legal transition). When the device is in this
1825 * state, only special requests will be accepted, all others will
1826 * be deferred. Since special requests may also be requeued requests,
1827 * a successful return doesn't guarantee the device will be
1828 * totally quiescent.
1830 * Must be called with user context, may sleep.
1832 * Returns zero if unsuccessful or an error if not.
1835 scsi_device_quiesce(struct scsi_device *sdev)
1837 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1841 scsi_run_queue(sdev->request_queue);
1842 while (sdev->device_busy) {
1843 msleep_interruptible(200);
1844 scsi_run_queue(sdev->request_queue);
1848 EXPORT_SYMBOL(scsi_device_quiesce);
1851 * scsi_device_resume - Restart user issued commands to a quiesced device.
1852 * @sdev: scsi device to resume.
1854 * Moves the device from quiesced back to running and restarts the
1857 * Must be called with user context, may sleep.
1860 scsi_device_resume(struct scsi_device *sdev)
1862 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1864 scsi_run_queue(sdev->request_queue);
1866 EXPORT_SYMBOL(scsi_device_resume);
1869 device_quiesce_fn(struct scsi_device *sdev, void *data)
1871 scsi_device_quiesce(sdev);
1875 scsi_target_quiesce(struct scsi_target *starget)
1877 starget_for_each_device(starget, NULL, device_quiesce_fn);
1879 EXPORT_SYMBOL(scsi_target_quiesce);
1882 device_resume_fn(struct scsi_device *sdev, void *data)
1884 scsi_device_resume(sdev);
1888 scsi_target_resume(struct scsi_target *starget)
1890 starget_for_each_device(starget, NULL, device_resume_fn);
1892 EXPORT_SYMBOL(scsi_target_resume);
1895 * scsi_internal_device_block - internal function to put a device
1896 * temporarily into the SDEV_BLOCK state
1897 * @sdev: device to block
1899 * Block request made by scsi lld's to temporarily stop all
1900 * scsi commands on the specified device. Called from interrupt
1901 * or normal process context.
1903 * Returns zero if successful or error if not
1906 * This routine transitions the device to the SDEV_BLOCK state
1907 * (which must be a legal transition). When the device is in this
1908 * state, all commands are deferred until the scsi lld reenables
1909 * the device with scsi_device_unblock or device_block_tmo fires.
1910 * This routine assumes the host_lock is held on entry.
1913 scsi_internal_device_block(struct scsi_device *sdev)
1915 request_queue_t *q = sdev->request_queue;
1916 unsigned long flags;
1919 err = scsi_device_set_state(sdev, SDEV_BLOCK);
1924 * The device has transitioned to SDEV_BLOCK. Stop the
1925 * block layer from calling the midlayer with this device's
1928 spin_lock_irqsave(q->queue_lock, flags);
1930 spin_unlock_irqrestore(q->queue_lock, flags);
1934 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
1937 * scsi_internal_device_unblock - resume a device after a block request
1938 * @sdev: device to resume
1940 * Called by scsi lld's or the midlayer to restart the device queue
1941 * for the previously suspended scsi device. Called from interrupt or
1942 * normal process context.
1944 * Returns zero if successful or error if not.
1947 * This routine transitions the device to the SDEV_RUNNING state
1948 * (which must be a legal transition) allowing the midlayer to
1949 * goose the queue for this device. This routine assumes the
1950 * host_lock is held upon entry.
1953 scsi_internal_device_unblock(struct scsi_device *sdev)
1955 request_queue_t *q = sdev->request_queue;
1957 unsigned long flags;
1960 * Try to transition the scsi device to SDEV_RUNNING
1961 * and goose the device queue if successful.
1963 err = scsi_device_set_state(sdev, SDEV_RUNNING);
1967 spin_lock_irqsave(q->queue_lock, flags);
1969 spin_unlock_irqrestore(q->queue_lock, flags);
1973 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
1976 device_block(struct scsi_device *sdev, void *data)
1978 scsi_internal_device_block(sdev);
1982 target_block(struct device *dev, void *data)
1984 if (scsi_is_target_device(dev))
1985 starget_for_each_device(to_scsi_target(dev), NULL,
1991 scsi_target_block(struct device *dev)
1993 if (scsi_is_target_device(dev))
1994 starget_for_each_device(to_scsi_target(dev), NULL,
1997 device_for_each_child(dev, NULL, target_block);
1999 EXPORT_SYMBOL_GPL(scsi_target_block);
2002 device_unblock(struct scsi_device *sdev, void *data)
2004 scsi_internal_device_unblock(sdev);
2008 target_unblock(struct device *dev, void *data)
2010 if (scsi_is_target_device(dev))
2011 starget_for_each_device(to_scsi_target(dev), NULL,
2017 scsi_target_unblock(struct device *dev)
2019 if (scsi_is_target_device(dev))
2020 starget_for_each_device(to_scsi_target(dev), NULL,
2023 device_for_each_child(dev, NULL, target_unblock);
2025 EXPORT_SYMBOL_GPL(scsi_target_unblock);