2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale
4 * SCSI queueing library.
5 * Initial versions: Eric Youngdale (eric@andante.org).
6 * Based upon conversations with large numbers
7 * of people at Linux Expo.
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/completion.h>
13 #include <linux/kernel.h>
14 #include <linux/mempool.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/pci.h>
18 #include <linux/delay.h>
20 #include <scsi/scsi.h>
21 #include <scsi/scsi_dbg.h>
22 #include <scsi/scsi_device.h>
23 #include <scsi/scsi_driver.h>
24 #include <scsi/scsi_eh.h>
25 #include <scsi/scsi_host.h>
26 #include <scsi/scsi_request.h>
28 #include "scsi_priv.h"
29 #include "scsi_logging.h"
32 #define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
33 #define SG_MEMPOOL_SIZE 32
35 struct scsi_host_sg_pool {
42 #if (SCSI_MAX_PHYS_SEGMENTS < 32)
43 #error SCSI_MAX_PHYS_SEGMENTS is too small
46 #define SP(x) { x, "sgpool-" #x }
47 static struct scsi_host_sg_pool scsi_sg_pools[] = {
51 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
53 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
55 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
57 #if (SCSI_MAX_PHYS_SEGMENTS > 256)
58 #error SCSI_MAX_PHYS_SEGMENTS is too large
68 * Function: scsi_insert_special_req()
70 * Purpose: Insert pre-formed request into request queue.
72 * Arguments: sreq - request that is ready to be queued.
73 * at_head - boolean. True if we should insert at head
74 * of queue, false if we should insert at tail.
76 * Lock status: Assumed that lock is not held upon entry.
80 * Notes: This function is called from character device and from
81 * ioctl types of functions where the caller knows exactly
82 * what SCSI command needs to be issued. The idea is that
83 * we merely inject the command into the queue (at the head
84 * for now), and then call the queue request function to actually
87 int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
90 * Because users of this function are apt to reuse requests with no
91 * modification, we have to sanitise the request flags here
93 sreq->sr_request->flags &= ~REQ_DONTPREP;
94 blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
99 static void scsi_run_queue(struct request_queue *q);
102 * Function: scsi_queue_insert()
104 * Purpose: Insert a command in the midlevel queue.
106 * Arguments: cmd - command that we are adding to queue.
107 * reason - why we are inserting command to queue.
109 * Lock status: Assumed that lock is not held upon entry.
113 * Notes: We do this for one of two cases. Either the host is busy
114 * and it cannot accept any more commands for the time being,
115 * or the device returned QUEUE_FULL and can accept no more
117 * Notes: This could be called either from an interrupt context or a
118 * normal process context.
120 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
122 struct Scsi_Host *host = cmd->device->host;
123 struct scsi_device *device = cmd->device;
124 struct request_queue *q = device->request_queue;
128 printk("Inserting command %p into mlqueue\n", cmd));
131 * Set the appropriate busy bit for the device/host.
133 * If the host/device isn't busy, assume that something actually
134 * completed, and that we should be able to queue a command now.
136 * Note that the prior mid-layer assumption that any host could
137 * always queue at least one command is now broken. The mid-layer
138 * will implement a user specifiable stall (see
139 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
140 * if a command is requeued with no other commands outstanding
141 * either for the device or for the host.
143 if (reason == SCSI_MLQUEUE_HOST_BUSY)
144 host->host_blocked = host->max_host_blocked;
145 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
146 device->device_blocked = device->max_device_blocked;
149 * Decrement the counters, since these commands are no longer
150 * active on the host/device.
152 scsi_device_unbusy(device);
155 * Requeue this command. It will go before all other commands
156 * that are already in the queue.
158 * NOTE: there is magic here about the way the queue is plugged if
159 * we have no outstanding commands.
161 * Although we *don't* plug the queue, we call the request
162 * function. The SCSI request function detects the blocked condition
163 * and plugs the queue appropriately.
165 spin_lock_irqsave(q->queue_lock, flags);
166 blk_requeue_request(q, cmd->request);
167 spin_unlock_irqrestore(q->queue_lock, flags);
175 * Function: scsi_do_req
177 * Purpose: Queue a SCSI request
179 * Arguments: sreq - command descriptor.
180 * cmnd - actual SCSI command to be performed.
181 * buffer - data buffer.
182 * bufflen - size of data buffer.
183 * done - completion function to be run.
184 * timeout - how long to let it run before timeout.
185 * retries - number of retries we allow.
187 * Lock status: No locks held upon entry.
191 * Notes: This function is only used for queueing requests for things
192 * like ioctls and character device requests - this is because
193 * we essentially just inject a request into the queue for the
196 * In order to support the scsi_device_quiesce function, we
197 * now inject requests on the *head* of the device queue
198 * rather than the tail.
200 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
201 void *buffer, unsigned bufflen,
202 void (*done)(struct scsi_cmnd *),
203 int timeout, int retries)
206 * If the upper level driver is reusing these things, then
207 * we should release the low-level block now. Another one will
208 * be allocated later when this request is getting queued.
210 __scsi_release_request(sreq);
213 * Our own function scsi_done (which marks the host as not busy,
214 * disables the timeout counter, etc) will be called by us or by the
215 * scsi_hosts[host].queuecommand() function needs to also call
216 * the completion function for the high level driver.
218 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
219 sreq->sr_bufflen = bufflen;
220 sreq->sr_buffer = buffer;
221 sreq->sr_allowed = retries;
222 sreq->sr_done = done;
223 sreq->sr_timeout_per_command = timeout;
225 if (sreq->sr_cmd_len == 0)
226 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
229 * head injection *required* here otherwise quiesce won't work
231 scsi_insert_special_req(sreq, 1);
233 EXPORT_SYMBOL(scsi_do_req);
235 /* This is the end routine we get to if a command was never attached
236 * to the request. Simply complete the request without changing
237 * rq_status; this will cause a DRIVER_ERROR. */
238 static void scsi_wait_req_end_io(struct request *req)
240 BUG_ON(!req->waiting);
242 complete(req->waiting);
245 void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
246 unsigned bufflen, int timeout, int retries)
248 DECLARE_COMPLETION(wait);
249 int write = sreq->sr_data_direction == DMA_TO_DEVICE;
252 req = blk_get_request(sreq->sr_device->request_queue, write,
254 if (bufflen && blk_rq_map_kern(sreq->sr_device->request_queue, req,
255 buffer, bufflen, __GFP_WAIT)) {
256 sreq->sr_result = DRIVER_ERROR << 24;
257 blk_put_request(req);
261 req->flags |= REQ_NOMERGE;
262 req->waiting = &wait;
263 req->end_io = scsi_wait_req_end_io;
264 req->cmd_len = COMMAND_SIZE(((u8 *)cmnd)[0]);
265 req->sense = sreq->sr_sense_buffer;
267 memcpy(req->cmd, cmnd, req->cmd_len);
268 req->timeout = timeout;
269 req->flags |= REQ_BLOCK_PC;
271 blk_insert_request(sreq->sr_device->request_queue, req,
272 sreq->sr_data_direction == DMA_TO_DEVICE, NULL);
273 wait_for_completion(&wait);
274 sreq->sr_request->waiting = NULL;
275 sreq->sr_result = req->errors;
277 sreq->sr_result |= (DRIVER_ERROR << 24);
279 blk_put_request(req);
282 EXPORT_SYMBOL(scsi_wait_req);
285 * Function: scsi_init_cmd_errh()
287 * Purpose: Initialize cmd fields related to error handling.
289 * Arguments: cmd - command that is ready to be queued.
293 * Notes: This function has the job of initializing a number of
294 * fields related to error handling. Typically this will
295 * be called once for each command, as required.
297 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
299 cmd->serial_number = 0;
301 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
303 if (cmd->cmd_len == 0)
304 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
307 * We need saved copies of a number of fields - this is because
308 * error handling may need to overwrite these with different values
309 * to run different commands, and once error handling is complete,
310 * we will need to restore these values prior to running the actual
313 cmd->old_use_sg = cmd->use_sg;
314 cmd->old_cmd_len = cmd->cmd_len;
315 cmd->sc_old_data_direction = cmd->sc_data_direction;
316 cmd->old_underflow = cmd->underflow;
317 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
318 cmd->buffer = cmd->request_buffer;
319 cmd->bufflen = cmd->request_bufflen;
325 * Function: scsi_setup_cmd_retry()
327 * Purpose: Restore the command state for a retry
329 * Arguments: cmd - command to be restored
333 * Notes: Immediately prior to retrying a command, we need
334 * to restore certain fields that we saved above.
336 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
338 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
339 cmd->request_buffer = cmd->buffer;
340 cmd->request_bufflen = cmd->bufflen;
341 cmd->use_sg = cmd->old_use_sg;
342 cmd->cmd_len = cmd->old_cmd_len;
343 cmd->sc_data_direction = cmd->sc_old_data_direction;
344 cmd->underflow = cmd->old_underflow;
347 void scsi_device_unbusy(struct scsi_device *sdev)
349 struct Scsi_Host *shost = sdev->host;
352 spin_lock_irqsave(shost->host_lock, flags);
354 if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
356 scsi_eh_wakeup(shost);
357 spin_unlock(shost->host_lock);
358 spin_lock(sdev->request_queue->queue_lock);
360 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
364 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
365 * and call blk_run_queue for all the scsi_devices on the target -
366 * including current_sdev first.
368 * Called with *no* scsi locks held.
370 static void scsi_single_lun_run(struct scsi_device *current_sdev)
372 struct Scsi_Host *shost = current_sdev->host;
373 struct scsi_device *sdev, *tmp;
374 struct scsi_target *starget = scsi_target(current_sdev);
377 spin_lock_irqsave(shost->host_lock, flags);
378 starget->starget_sdev_user = NULL;
379 spin_unlock_irqrestore(shost->host_lock, flags);
382 * Call blk_run_queue for all LUNs on the target, starting with
383 * current_sdev. We race with others (to set starget_sdev_user),
384 * but in most cases, we will be first. Ideally, each LU on the
385 * target would get some limited time or requests on the target.
387 blk_run_queue(current_sdev->request_queue);
389 spin_lock_irqsave(shost->host_lock, flags);
390 if (starget->starget_sdev_user)
392 list_for_each_entry_safe(sdev, tmp, &starget->devices,
393 same_target_siblings) {
394 if (sdev == current_sdev)
396 if (scsi_device_get(sdev))
399 spin_unlock_irqrestore(shost->host_lock, flags);
400 blk_run_queue(sdev->request_queue);
401 spin_lock_irqsave(shost->host_lock, flags);
403 scsi_device_put(sdev);
406 spin_unlock_irqrestore(shost->host_lock, flags);
410 * Function: scsi_run_queue()
412 * Purpose: Select a proper request queue to serve next
414 * Arguments: q - last request's queue
418 * Notes: The previous command was completely finished, start
419 * a new one if possible.
421 static void scsi_run_queue(struct request_queue *q)
423 struct scsi_device *sdev = q->queuedata;
424 struct Scsi_Host *shost = sdev->host;
427 if (sdev->single_lun)
428 scsi_single_lun_run(sdev);
430 spin_lock_irqsave(shost->host_lock, flags);
431 while (!list_empty(&shost->starved_list) &&
432 !shost->host_blocked && !shost->host_self_blocked &&
433 !((shost->can_queue > 0) &&
434 (shost->host_busy >= shost->can_queue))) {
436 * As long as shost is accepting commands and we have
437 * starved queues, call blk_run_queue. scsi_request_fn
438 * drops the queue_lock and can add us back to the
441 * host_lock protects the starved_list and starved_entry.
442 * scsi_request_fn must get the host_lock before checking
443 * or modifying starved_list or starved_entry.
445 sdev = list_entry(shost->starved_list.next,
446 struct scsi_device, starved_entry);
447 list_del_init(&sdev->starved_entry);
448 spin_unlock_irqrestore(shost->host_lock, flags);
450 blk_run_queue(sdev->request_queue);
452 spin_lock_irqsave(shost->host_lock, flags);
453 if (unlikely(!list_empty(&sdev->starved_entry)))
455 * sdev lost a race, and was put back on the
456 * starved list. This is unlikely but without this
457 * in theory we could loop forever.
461 spin_unlock_irqrestore(shost->host_lock, flags);
467 * Function: scsi_requeue_command()
469 * Purpose: Handle post-processing of completed commands.
471 * Arguments: q - queue to operate on
472 * cmd - command that may need to be requeued.
476 * Notes: After command completion, there may be blocks left
477 * over which weren't finished by the previous command
478 * this can be for a number of reasons - the main one is
479 * I/O errors in the middle of the request, in which case
480 * we need to request the blocks that come after the bad
483 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
487 cmd->request->flags &= ~REQ_DONTPREP;
489 spin_lock_irqsave(q->queue_lock, flags);
490 blk_requeue_request(q, cmd->request);
491 spin_unlock_irqrestore(q->queue_lock, flags);
496 void scsi_next_command(struct scsi_cmnd *cmd)
498 struct request_queue *q = cmd->device->request_queue;
500 scsi_put_command(cmd);
504 void scsi_run_host_queues(struct Scsi_Host *shost)
506 struct scsi_device *sdev;
508 shost_for_each_device(sdev, shost)
509 scsi_run_queue(sdev->request_queue);
513 * Function: scsi_end_request()
515 * Purpose: Post-processing of completed commands (usually invoked at end
516 * of upper level post-processing and scsi_io_completion).
518 * Arguments: cmd - command that is complete.
519 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
520 * bytes - number of bytes of completed I/O
521 * requeue - indicates whether we should requeue leftovers.
523 * Lock status: Assumed that lock is not held upon entry.
525 * Returns: cmd if requeue done or required, NULL otherwise
527 * Notes: This is called for block device requests in order to
528 * mark some number of sectors as complete.
530 * We are guaranteeing that the request queue will be goosed
531 * at some point during this call.
533 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
534 int bytes, int requeue)
536 request_queue_t *q = cmd->device->request_queue;
537 struct request *req = cmd->request;
541 * If there are blocks left over at the end, set up the command
542 * to queue the remainder of them.
544 if (end_that_request_chunk(req, uptodate, bytes)) {
545 int leftover = (req->hard_nr_sectors << 9);
547 if (blk_pc_request(req))
548 leftover = req->data_len;
550 /* kill remainder if no retrys */
551 if (!uptodate && blk_noretry_request(req))
552 end_that_request_chunk(req, 0, leftover);
556 * Bleah. Leftovers again. Stick the
557 * leftovers in the front of the
558 * queue, and goose the queue again.
560 scsi_requeue_command(q, cmd);
566 add_disk_randomness(req->rq_disk);
568 spin_lock_irqsave(q->queue_lock, flags);
569 if (blk_rq_tagged(req))
570 blk_queue_end_tag(q, req);
571 end_that_request_last(req);
572 spin_unlock_irqrestore(q->queue_lock, flags);
575 * This will goose the queue request function at the end, so we don't
576 * need to worry about launching another command.
578 scsi_next_command(cmd);
582 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
584 struct scsi_host_sg_pool *sgp;
585 struct scatterlist *sgl;
587 BUG_ON(!cmd->use_sg);
589 switch (cmd->use_sg) {
599 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
603 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
607 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
618 sgp = scsi_sg_pools + cmd->sglist_len;
619 sgl = mempool_alloc(sgp->pool, gfp_mask);
623 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
625 struct scsi_host_sg_pool *sgp;
627 BUG_ON(index >= SG_MEMPOOL_NR);
629 sgp = scsi_sg_pools + index;
630 mempool_free(sgl, sgp->pool);
634 * Function: scsi_release_buffers()
636 * Purpose: Completion processing for block device I/O requests.
638 * Arguments: cmd - command that we are bailing.
640 * Lock status: Assumed that no lock is held upon entry.
644 * Notes: In the event that an upper level driver rejects a
645 * command, we must release resources allocated during
646 * the __init_io() function. Primarily this would involve
647 * the scatter-gather table, and potentially any bounce
650 static void scsi_release_buffers(struct scsi_cmnd *cmd)
652 struct request *req = cmd->request;
655 * Free up any indirection buffers we allocated for DMA purposes.
658 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
659 else if (cmd->request_buffer != req->buffer)
660 kfree(cmd->request_buffer);
663 * Zero these out. They now point to freed memory, and it is
664 * dangerous to hang onto the pointers.
668 cmd->request_buffer = NULL;
669 cmd->request_bufflen = 0;
673 * Function: scsi_io_completion()
675 * Purpose: Completion processing for block device I/O requests.
677 * Arguments: cmd - command that is finished.
679 * Lock status: Assumed that no lock is held upon entry.
683 * Notes: This function is matched in terms of capabilities to
684 * the function that created the scatter-gather list.
685 * In other words, if there are no bounce buffers
686 * (the normal case for most drivers), we don't need
687 * the logic to deal with cleaning up afterwards.
689 * We must do one of several things here:
691 * a) Call scsi_end_request. This will finish off the
692 * specified number of sectors. If we are done, the
693 * command block will be released, and the queue
694 * function will be goosed. If we are not done, then
695 * scsi_end_request will directly goose the queue.
697 * b) We can just use scsi_requeue_command() here. This would
698 * be used if we just wanted to retry, for example.
700 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
701 unsigned int block_bytes)
703 int result = cmd->result;
704 int this_count = cmd->bufflen;
705 request_queue_t *q = cmd->device->request_queue;
706 struct request *req = cmd->request;
707 int clear_errors = 1;
708 struct scsi_sense_hdr sshdr;
710 int sense_deferred = 0;
712 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
716 * Free up any indirection buffers we allocated for DMA purposes.
717 * For the case of a READ, we need to copy the data out of the
718 * bounce buffer and into the real buffer.
721 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
722 else if (cmd->buffer != req->buffer) {
723 if (rq_data_dir(req) == READ) {
725 char *to = bio_kmap_irq(req->bio, &flags);
726 memcpy(to, cmd->buffer, cmd->bufflen);
727 bio_kunmap_irq(to, &flags);
733 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
735 sense_deferred = scsi_sense_is_deferred(&sshdr);
737 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
738 req->errors = result;
741 if (sense_valid && req->sense) {
743 * SG_IO wants current and deferred errors
745 int len = 8 + cmd->sense_buffer[7];
747 if (len > SCSI_SENSE_BUFFERSIZE)
748 len = SCSI_SENSE_BUFFERSIZE;
749 memcpy(req->sense, cmd->sense_buffer, len);
750 req->sense_len = len;
753 req->data_len = cmd->resid;
757 * Zero these out. They now point to freed memory, and it is
758 * dangerous to hang onto the pointers.
762 cmd->request_buffer = NULL;
763 cmd->request_bufflen = 0;
766 * Next deal with any sectors which we were able to correctly
769 if (good_bytes >= 0) {
770 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
771 req->nr_sectors, good_bytes));
772 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
777 * If multiple sectors are requested in one buffer, then
778 * they will have been finished off by the first command.
779 * If not, then we have a multi-buffer command.
781 * If block_bytes != 0, it means we had a medium error
782 * of some sort, and that we want to mark some number of
783 * sectors as not uptodate. Thus we want to inhibit
784 * requeueing right here - we will requeue down below
785 * when we handle the bad sectors.
787 cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
790 * If the command completed without error, then either finish off the
791 * rest of the command, or start a new one.
793 if (result == 0 || cmd == NULL ) {
798 * Now, if we were good little boys and girls, Santa left us a request
799 * sense buffer. We can extract information from this, so we
800 * can choose a block to remap, etc.
802 if (sense_valid && !sense_deferred) {
803 switch (sshdr.sense_key) {
805 if (cmd->device->removable) {
806 /* detected disc change. set a bit
807 * and quietly refuse further access.
809 cmd->device->changed = 1;
810 cmd = scsi_end_request(cmd, 0,
815 * Must have been a power glitch, or a
816 * bus reset. Could not have been a
817 * media change, so we just retry the
818 * request and see what happens.
820 scsi_requeue_command(q, cmd);
824 case ILLEGAL_REQUEST:
826 * If we had an ILLEGAL REQUEST returned, then we may
827 * have performed an unsupported command. The only
828 * thing this should be would be a ten byte read where
829 * only a six byte read was supported. Also, on a
830 * system where READ CAPACITY failed, we may have read
831 * past the end of the disk.
833 if (cmd->device->use_10_for_rw &&
834 (cmd->cmnd[0] == READ_10 ||
835 cmd->cmnd[0] == WRITE_10)) {
836 cmd->device->use_10_for_rw = 0;
838 * This will cause a retry with a 6-byte
841 scsi_requeue_command(q, cmd);
844 cmd = scsi_end_request(cmd, 0, this_count, 1);
850 * If the device is in the process of becoming ready,
853 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
854 scsi_requeue_command(q, cmd);
857 printk(KERN_INFO "Device %s not ready.\n",
858 req->rq_disk ? req->rq_disk->disk_name : "");
859 cmd = scsi_end_request(cmd, 0, this_count, 1);
861 case VOLUME_OVERFLOW:
862 printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
863 cmd->device->host->host_no,
864 (int)cmd->device->channel,
865 (int)cmd->device->id, (int)cmd->device->lun);
866 __scsi_print_command(cmd->data_cmnd);
867 scsi_print_sense("", cmd);
868 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
873 } /* driver byte != 0 */
874 if (host_byte(result) == DID_RESET) {
876 * Third party bus reset or reset for error
877 * recovery reasons. Just retry the request
878 * and see what happens.
880 scsi_requeue_command(q, cmd);
884 if (!(req->flags & REQ_SPECIAL))
885 printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
886 "= 0x%x\n", cmd->device->host->host_no,
887 cmd->device->channel,
889 cmd->device->lun, result);
891 if (driver_byte(result) & DRIVER_SENSE)
892 scsi_print_sense("", cmd);
894 * Mark a single buffer as not uptodate. Queue the remainder.
895 * We sometimes get this cruft in the event that a medium error
896 * isn't properly reported.
898 block_bytes = req->hard_cur_sectors << 9;
900 block_bytes = req->data_len;
901 cmd = scsi_end_request(cmd, 0, block_bytes, 1);
904 EXPORT_SYMBOL(scsi_io_completion);
907 * Function: scsi_init_io()
909 * Purpose: SCSI I/O initialize function.
911 * Arguments: cmd - Command descriptor we wish to initialize
913 * Returns: 0 on success
914 * BLKPREP_DEFER if the failure is retryable
915 * BLKPREP_KILL if the failure is fatal
917 static int scsi_init_io(struct scsi_cmnd *cmd)
919 struct request *req = cmd->request;
920 struct scatterlist *sgpnt;
924 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
926 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
927 cmd->request_bufflen = req->data_len;
928 cmd->request_buffer = req->data;
929 req->buffer = req->data;
935 * we used to not use scatter-gather for single segment request,
936 * but now we do (it makes highmem I/O easier to support without
939 cmd->use_sg = req->nr_phys_segments;
942 * if sg table allocation fails, requeue request later.
944 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
945 if (unlikely(!sgpnt))
946 return BLKPREP_DEFER;
948 cmd->request_buffer = (char *) sgpnt;
949 cmd->request_bufflen = req->nr_sectors << 9;
950 if (blk_pc_request(req))
951 cmd->request_bufflen = req->data_len;
955 * Next, walk the list, and fill in the addresses and sizes of
958 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
961 * mapped well, send it off
963 if (likely(count <= cmd->use_sg)) {
968 printk(KERN_ERR "Incorrect number of segments after building list\n");
969 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
970 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
971 req->current_nr_sectors);
973 /* release the command and kill it */
974 scsi_release_buffers(cmd);
975 scsi_put_command(cmd);
979 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
981 struct scsi_device *sdev = q->queuedata;
982 struct scsi_driver *drv;
984 if (sdev->sdev_state == SDEV_RUNNING) {
985 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
987 if (drv->prepare_flush)
988 return drv->prepare_flush(q, rq);
994 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
996 struct scsi_device *sdev = q->queuedata;
997 struct request *flush_rq = rq->end_io_data;
998 struct scsi_driver *drv;
1000 if (flush_rq->errors) {
1001 printk("scsi: barrier error, disabling flush support\n");
1002 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1005 if (sdev->sdev_state == SDEV_RUNNING) {
1006 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1007 drv->end_flush(q, rq);
1011 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1012 sector_t *error_sector)
1014 struct scsi_device *sdev = q->queuedata;
1015 struct scsi_driver *drv;
1017 if (sdev->sdev_state != SDEV_RUNNING)
1020 drv = *(struct scsi_driver **) disk->private_data;
1021 if (drv->issue_flush)
1022 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1027 static void scsi_generic_done(struct scsi_cmnd *cmd)
1029 BUG_ON(!blk_pc_request(cmd->request));
1030 scsi_io_completion(cmd, cmd->result == 0 ? cmd->bufflen : 0, 0);
1033 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1035 struct scsi_device *sdev = q->queuedata;
1036 struct scsi_cmnd *cmd;
1037 int specials_only = 0;
1040 * Just check to see if the device is online. If it isn't, we
1041 * refuse to process any commands. The device must be brought
1042 * online before trying any recovery commands
1044 if (unlikely(!scsi_device_online(sdev))) {
1045 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1046 sdev->host->host_no, sdev->id, sdev->lun);
1047 return BLKPREP_KILL;
1049 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1050 /* OK, we're not in a running state don't prep
1052 if (sdev->sdev_state == SDEV_DEL) {
1053 /* Device is fully deleted, no commands
1054 * at all allowed down */
1055 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1056 sdev->host->host_no, sdev->id, sdev->lun);
1057 return BLKPREP_KILL;
1059 /* OK, we only allow special commands (i.e. not
1060 * user initiated ones */
1061 specials_only = sdev->sdev_state;
1065 * Find the actual device driver associated with this command.
1066 * The SPECIAL requests are things like character device or
1067 * ioctls, which did not originate from ll_rw_blk. Note that
1068 * the special field is also used to indicate the cmd for
1069 * the remainder of a partially fulfilled request that can
1070 * come up when there is a medium error. We have to treat
1071 * these two cases differently. We differentiate by looking
1072 * at request->cmd, as this tells us the real story.
1074 if (req->flags & REQ_SPECIAL && req->special) {
1075 struct scsi_request *sreq = req->special;
1077 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1078 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1081 scsi_init_cmd_from_req(cmd, sreq);
1084 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1086 if(unlikely(specials_only) && !(req->flags & REQ_SPECIAL)) {
1087 if(specials_only == SDEV_QUIESCE ||
1088 specials_only == SDEV_BLOCK)
1089 return BLKPREP_DEFER;
1091 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1092 sdev->host->host_no, sdev->id, sdev->lun);
1093 return BLKPREP_KILL;
1098 * Now try and find a command block that we can use.
1100 if (!req->special) {
1101 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1107 /* pull a tag out of the request if we have one */
1108 cmd->tag = req->tag;
1110 blk_dump_rq_flags(req, "SCSI bad req");
1111 return BLKPREP_KILL;
1114 /* note the overloading of req->special. When the tag
1115 * is active it always means cmd. If the tag goes
1116 * back for re-queueing, it may be reset */
1121 * FIXME: drop the lock here because the functions below
1122 * expect to be called without the queue lock held. Also,
1123 * previously, we dequeued the request before dropping the
1124 * lock. We hope REQ_STARTED prevents anything untoward from
1127 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1128 struct scsi_driver *drv;
1132 * This will do a couple of things:
1133 * 1) Fill in the actual SCSI command.
1134 * 2) Fill in any other upper-level specific fields
1137 * If this returns 0, it means that the request failed
1138 * (reading past end of disk, reading offline device,
1139 * etc). This won't actually talk to the device, but
1140 * some kinds of consistency checking may cause the
1141 * request to be rejected immediately.
1145 * This sets up the scatter-gather table (allocating if
1148 ret = scsi_init_io(cmd);
1149 if (ret) /* BLKPREP_KILL return also releases the command */
1153 * Initialize the actual SCSI command for this request.
1156 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1157 if (unlikely(!drv->init_command(cmd))) {
1158 scsi_release_buffers(cmd);
1159 scsi_put_command(cmd);
1160 return BLKPREP_KILL;
1163 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1164 if (rq_data_dir(req) == WRITE)
1165 cmd->sc_data_direction = DMA_TO_DEVICE;
1166 else if (req->data_len)
1167 cmd->sc_data_direction = DMA_FROM_DEVICE;
1169 cmd->sc_data_direction = DMA_NONE;
1171 cmd->transfersize = req->data_len;
1173 cmd->timeout_per_command = req->timeout;
1174 cmd->done = scsi_generic_done;
1179 * The request is now prepped, no need to come back here
1181 req->flags |= REQ_DONTPREP;
1185 /* If we defer, the elv_next_request() returns NULL, but the
1186 * queue must be restarted, so we plug here if no returning
1187 * command will automatically do that. */
1188 if (sdev->device_busy == 0)
1190 return BLKPREP_DEFER;
1194 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1197 * Called with the queue_lock held.
1199 static inline int scsi_dev_queue_ready(struct request_queue *q,
1200 struct scsi_device *sdev)
1202 if (sdev->device_busy >= sdev->queue_depth)
1204 if (sdev->device_busy == 0 && sdev->device_blocked) {
1206 * unblock after device_blocked iterates to zero
1208 if (--sdev->device_blocked == 0) {
1210 printk("scsi%d (%d:%d) unblocking device at"
1211 " zero depth\n", sdev->host->host_no,
1212 sdev->id, sdev->lun));
1218 if (sdev->device_blocked)
1225 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1226 * return 0. We must end up running the queue again whenever 0 is
1227 * returned, else IO can hang.
1229 * Called with host_lock held.
1231 static inline int scsi_host_queue_ready(struct request_queue *q,
1232 struct Scsi_Host *shost,
1233 struct scsi_device *sdev)
1235 if (test_bit(SHOST_RECOVERY, &shost->shost_state))
1237 if (shost->host_busy == 0 && shost->host_blocked) {
1239 * unblock after host_blocked iterates to zero
1241 if (--shost->host_blocked == 0) {
1243 printk("scsi%d unblocking host at zero depth\n",
1250 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1251 shost->host_blocked || shost->host_self_blocked) {
1252 if (list_empty(&sdev->starved_entry))
1253 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1257 /* We're OK to process the command, so we can't be starved */
1258 if (!list_empty(&sdev->starved_entry))
1259 list_del_init(&sdev->starved_entry);
1265 * Kill requests for a dead device
1267 static void scsi_kill_requests(request_queue_t *q)
1269 struct request *req;
1271 while ((req = elv_next_request(q)) != NULL) {
1272 blkdev_dequeue_request(req);
1273 req->flags |= REQ_QUIET;
1274 while (end_that_request_first(req, 0, req->nr_sectors))
1276 end_that_request_last(req);
1281 * Function: scsi_request_fn()
1283 * Purpose: Main strategy routine for SCSI.
1285 * Arguments: q - Pointer to actual queue.
1289 * Lock status: IO request lock assumed to be held when called.
1291 static void scsi_request_fn(struct request_queue *q)
1293 struct scsi_device *sdev = q->queuedata;
1294 struct Scsi_Host *shost;
1295 struct scsi_cmnd *cmd;
1296 struct request *req;
1299 printk("scsi: killing requests for dead queue\n");
1300 scsi_kill_requests(q);
1304 if(!get_device(&sdev->sdev_gendev))
1305 /* We must be tearing the block queue down already */
1309 * To start with, we keep looping until the queue is empty, or until
1310 * the host is no longer able to accept any more requests.
1313 while (!blk_queue_plugged(q)) {
1316 * get next queueable request. We do this early to make sure
1317 * that the request is fully prepared even if we cannot
1320 req = elv_next_request(q);
1321 if (!req || !scsi_dev_queue_ready(q, sdev))
1324 if (unlikely(!scsi_device_online(sdev))) {
1325 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1326 sdev->host->host_no, sdev->id, sdev->lun);
1327 blkdev_dequeue_request(req);
1328 req->flags |= REQ_QUIET;
1329 while (end_that_request_first(req, 0, req->nr_sectors))
1331 end_that_request_last(req);
1337 * Remove the request from the request list.
1339 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1340 blkdev_dequeue_request(req);
1341 sdev->device_busy++;
1343 spin_unlock(q->queue_lock);
1344 spin_lock(shost->host_lock);
1346 if (!scsi_host_queue_ready(q, shost, sdev))
1348 if (sdev->single_lun) {
1349 if (scsi_target(sdev)->starget_sdev_user &&
1350 scsi_target(sdev)->starget_sdev_user != sdev)
1352 scsi_target(sdev)->starget_sdev_user = sdev;
1357 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1358 * take the lock again.
1360 spin_unlock_irq(shost->host_lock);
1363 if (unlikely(cmd == NULL)) {
1364 printk(KERN_CRIT "impossible request in %s.\n"
1365 "please mail a stack trace to "
1366 "linux-scsi@vger.kernel.org",
1372 * Finally, initialize any error handling parameters, and set up
1373 * the timers for timeouts.
1375 scsi_init_cmd_errh(cmd);
1378 * Dispatch the command to the low-level driver.
1380 rtn = scsi_dispatch_cmd(cmd);
1381 spin_lock_irq(q->queue_lock);
1383 /* we're refusing the command; because of
1384 * the way locks get dropped, we need to
1385 * check here if plugging is required */
1386 if(sdev->device_busy == 0)
1396 spin_unlock_irq(shost->host_lock);
1399 * lock q, handle tag, requeue req, and decrement device_busy. We
1400 * must return with queue_lock held.
1402 * Decrementing device_busy without checking it is OK, as all such
1403 * cases (host limits or settings) should run the queue at some
1406 spin_lock_irq(q->queue_lock);
1407 blk_requeue_request(q, req);
1408 sdev->device_busy--;
1409 if(sdev->device_busy == 0)
1412 /* must be careful here...if we trigger the ->remove() function
1413 * we cannot be holding the q lock */
1414 spin_unlock_irq(q->queue_lock);
1415 put_device(&sdev->sdev_gendev);
1416 spin_lock_irq(q->queue_lock);
1419 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1421 struct device *host_dev;
1422 u64 bounce_limit = 0xffffffff;
1424 if (shost->unchecked_isa_dma)
1425 return BLK_BOUNCE_ISA;
1427 * Platforms with virtual-DMA translation
1428 * hardware have no practical limit.
1430 if (!PCI_DMA_BUS_IS_PHYS)
1431 return BLK_BOUNCE_ANY;
1433 host_dev = scsi_get_device(shost);
1434 if (host_dev && host_dev->dma_mask)
1435 bounce_limit = *host_dev->dma_mask;
1437 return bounce_limit;
1439 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1441 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1443 struct Scsi_Host *shost = sdev->host;
1444 struct request_queue *q;
1446 q = blk_init_queue(scsi_request_fn, NULL);
1450 blk_queue_prep_rq(q, scsi_prep_fn);
1452 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1453 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1454 blk_queue_max_sectors(q, shost->max_sectors);
1455 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1456 blk_queue_segment_boundary(q, shost->dma_boundary);
1457 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1460 * ordered tags are superior to flush ordering
1462 if (shost->ordered_tag)
1463 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1464 else if (shost->ordered_flush) {
1465 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1466 q->prepare_flush_fn = scsi_prepare_flush_fn;
1467 q->end_flush_fn = scsi_end_flush_fn;
1470 if (!shost->use_clustering)
1471 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1475 void scsi_free_queue(struct request_queue *q)
1477 blk_cleanup_queue(q);
1481 * Function: scsi_block_requests()
1483 * Purpose: Utility function used by low-level drivers to prevent further
1484 * commands from being queued to the device.
1486 * Arguments: shost - Host in question
1490 * Lock status: No locks are assumed held.
1492 * Notes: There is no timer nor any other means by which the requests
1493 * get unblocked other than the low-level driver calling
1494 * scsi_unblock_requests().
1496 void scsi_block_requests(struct Scsi_Host *shost)
1498 shost->host_self_blocked = 1;
1500 EXPORT_SYMBOL(scsi_block_requests);
1503 * Function: scsi_unblock_requests()
1505 * Purpose: Utility function used by low-level drivers to allow further
1506 * commands from being queued to the device.
1508 * Arguments: shost - Host in question
1512 * Lock status: No locks are assumed held.
1514 * Notes: There is no timer nor any other means by which the requests
1515 * get unblocked other than the low-level driver calling
1516 * scsi_unblock_requests().
1518 * This is done as an API function so that changes to the
1519 * internals of the scsi mid-layer won't require wholesale
1520 * changes to drivers that use this feature.
1522 void scsi_unblock_requests(struct Scsi_Host *shost)
1524 shost->host_self_blocked = 0;
1525 scsi_run_host_queues(shost);
1527 EXPORT_SYMBOL(scsi_unblock_requests);
1529 int __init scsi_init_queue(void)
1533 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1534 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1535 int size = sgp->size * sizeof(struct scatterlist);
1537 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1538 SLAB_HWCACHE_ALIGN, NULL, NULL);
1540 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1544 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1545 mempool_alloc_slab, mempool_free_slab,
1548 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1556 void scsi_exit_queue(void)
1560 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1561 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1562 mempool_destroy(sgp->pool);
1563 kmem_cache_destroy(sgp->slab);
1567 * __scsi_mode_sense - issue a mode sense, falling back from 10 to
1568 * six bytes if necessary.
1569 * @sreq: SCSI request to fill in with the MODE_SENSE
1570 * @dbd: set if mode sense will allow block descriptors to be returned
1571 * @modepage: mode page being requested
1572 * @buffer: request buffer (may not be smaller than eight bytes)
1573 * @len: length of request buffer.
1574 * @timeout: command timeout
1575 * @retries: number of retries before failing
1576 * @data: returns a structure abstracting the mode header data
1578 * Returns zero if unsuccessful, or the header offset (either 4
1579 * or 8 depending on whether a six or ten byte command was
1580 * issued) if successful.
1583 __scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
1584 unsigned char *buffer, int len, int timeout, int retries,
1585 struct scsi_mode_data *data) {
1586 unsigned char cmd[12];
1590 memset(data, 0, sizeof(*data));
1591 memset(&cmd[0], 0, 12);
1592 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1596 use_10_for_ms = sreq->sr_device->use_10_for_ms;
1598 if (use_10_for_ms) {
1602 cmd[0] = MODE_SENSE_10;
1609 cmd[0] = MODE_SENSE;
1614 sreq->sr_cmd_len = 0;
1615 memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
1616 sreq->sr_data_direction = DMA_FROM_DEVICE;
1618 memset(buffer, 0, len);
1620 scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
1622 /* This code looks awful: what it's doing is making sure an
1623 * ILLEGAL REQUEST sense return identifies the actual command
1624 * byte as the problem. MODE_SENSE commands can return
1625 * ILLEGAL REQUEST if the code page isn't supported */
1627 if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
1628 (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
1629 struct scsi_sense_hdr sshdr;
1631 if (scsi_request_normalize_sense(sreq, &sshdr)) {
1632 if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
1633 (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
1635 * Invalid command operation code
1637 sreq->sr_device->use_10_for_ms = 0;
1643 if(scsi_status_is_good(sreq->sr_result)) {
1644 data->header_length = header_length;
1646 data->length = buffer[0]*256 + buffer[1] + 2;
1647 data->medium_type = buffer[2];
1648 data->device_specific = buffer[3];
1649 data->longlba = buffer[4] & 0x01;
1650 data->block_descriptor_length = buffer[6]*256
1653 data->length = buffer[0] + 1;
1654 data->medium_type = buffer[1];
1655 data->device_specific = buffer[2];
1656 data->block_descriptor_length = buffer[3];
1660 return sreq->sr_result;
1662 EXPORT_SYMBOL(__scsi_mode_sense);
1665 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1666 * six bytes if necessary.
1667 * @sdev: scsi device to send command to.
1668 * @dbd: set if mode sense will disable block descriptors in the return
1669 * @modepage: mode page being requested
1670 * @buffer: request buffer (may not be smaller than eight bytes)
1671 * @len: length of request buffer.
1672 * @timeout: command timeout
1673 * @retries: number of retries before failing
1675 * Returns zero if unsuccessful, or the header offset (either 4
1676 * or 8 depending on whether a six or ten byte command was
1677 * issued) if successful.
1680 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1681 unsigned char *buffer, int len, int timeout, int retries,
1682 struct scsi_mode_data *data)
1684 struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1690 ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
1691 timeout, retries, data);
1693 scsi_release_request(sreq);
1697 EXPORT_SYMBOL(scsi_mode_sense);
1700 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1702 struct scsi_request *sreq;
1704 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1708 sreq = scsi_allocate_request(sdev, GFP_KERNEL);
1712 sreq->sr_data_direction = DMA_NONE;
1713 scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
1715 if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
1716 struct scsi_sense_hdr sshdr;
1718 if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
1719 ((sshdr.sense_key == UNIT_ATTENTION) ||
1720 (sshdr.sense_key == NOT_READY))) {
1722 sreq->sr_result = 0;
1725 result = sreq->sr_result;
1726 scsi_release_request(sreq);
1729 EXPORT_SYMBOL(scsi_test_unit_ready);
1732 * scsi_device_set_state - Take the given device through the device
1734 * @sdev: scsi device to change the state of.
1735 * @state: state to change to.
1737 * Returns zero if unsuccessful or an error if the requested
1738 * transition is illegal.
1741 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1743 enum scsi_device_state oldstate = sdev->sdev_state;
1745 if (state == oldstate)
1750 /* There are no legal states that come back to
1751 * created. This is the manually initialised start
1821 sdev->sdev_state = state;
1825 SCSI_LOG_ERROR_RECOVERY(1,
1826 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1827 "Illegal state transition %s->%s\n",
1828 scsi_device_state_name(oldstate),
1829 scsi_device_state_name(state))
1833 EXPORT_SYMBOL(scsi_device_set_state);
1836 * scsi_device_quiesce - Block user issued commands.
1837 * @sdev: scsi device to quiesce.
1839 * This works by trying to transition to the SDEV_QUIESCE state
1840 * (which must be a legal transition). When the device is in this
1841 * state, only special requests will be accepted, all others will
1842 * be deferred. Since special requests may also be requeued requests,
1843 * a successful return doesn't guarantee the device will be
1844 * totally quiescent.
1846 * Must be called with user context, may sleep.
1848 * Returns zero if unsuccessful or an error if not.
1851 scsi_device_quiesce(struct scsi_device *sdev)
1853 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1857 scsi_run_queue(sdev->request_queue);
1858 while (sdev->device_busy) {
1859 msleep_interruptible(200);
1860 scsi_run_queue(sdev->request_queue);
1864 EXPORT_SYMBOL(scsi_device_quiesce);
1867 * scsi_device_resume - Restart user issued commands to a quiesced device.
1868 * @sdev: scsi device to resume.
1870 * Moves the device from quiesced back to running and restarts the
1873 * Must be called with user context, may sleep.
1876 scsi_device_resume(struct scsi_device *sdev)
1878 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1880 scsi_run_queue(sdev->request_queue);
1882 EXPORT_SYMBOL(scsi_device_resume);
1885 device_quiesce_fn(struct scsi_device *sdev, void *data)
1887 scsi_device_quiesce(sdev);
1891 scsi_target_quiesce(struct scsi_target *starget)
1893 starget_for_each_device(starget, NULL, device_quiesce_fn);
1895 EXPORT_SYMBOL(scsi_target_quiesce);
1898 device_resume_fn(struct scsi_device *sdev, void *data)
1900 scsi_device_resume(sdev);
1904 scsi_target_resume(struct scsi_target *starget)
1906 starget_for_each_device(starget, NULL, device_resume_fn);
1908 EXPORT_SYMBOL(scsi_target_resume);
1911 * scsi_internal_device_block - internal function to put a device
1912 * temporarily into the SDEV_BLOCK state
1913 * @sdev: device to block
1915 * Block request made by scsi lld's to temporarily stop all
1916 * scsi commands on the specified device. Called from interrupt
1917 * or normal process context.
1919 * Returns zero if successful or error if not
1922 * This routine transitions the device to the SDEV_BLOCK state
1923 * (which must be a legal transition). When the device is in this
1924 * state, all commands are deferred until the scsi lld reenables
1925 * the device with scsi_device_unblock or device_block_tmo fires.
1926 * This routine assumes the host_lock is held on entry.
1929 scsi_internal_device_block(struct scsi_device *sdev)
1931 request_queue_t *q = sdev->request_queue;
1932 unsigned long flags;
1935 err = scsi_device_set_state(sdev, SDEV_BLOCK);
1940 * The device has transitioned to SDEV_BLOCK. Stop the
1941 * block layer from calling the midlayer with this device's
1944 spin_lock_irqsave(q->queue_lock, flags);
1946 spin_unlock_irqrestore(q->queue_lock, flags);
1950 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
1953 * scsi_internal_device_unblock - resume a device after a block request
1954 * @sdev: device to resume
1956 * Called by scsi lld's or the midlayer to restart the device queue
1957 * for the previously suspended scsi device. Called from interrupt or
1958 * normal process context.
1960 * Returns zero if successful or error if not.
1963 * This routine transitions the device to the SDEV_RUNNING state
1964 * (which must be a legal transition) allowing the midlayer to
1965 * goose the queue for this device. This routine assumes the
1966 * host_lock is held upon entry.
1969 scsi_internal_device_unblock(struct scsi_device *sdev)
1971 request_queue_t *q = sdev->request_queue;
1973 unsigned long flags;
1976 * Try to transition the scsi device to SDEV_RUNNING
1977 * and goose the device queue if successful.
1979 err = scsi_device_set_state(sdev, SDEV_RUNNING);
1983 spin_lock_irqsave(q->queue_lock, flags);
1985 spin_unlock_irqrestore(q->queue_lock, flags);
1989 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
1992 device_block(struct scsi_device *sdev, void *data)
1994 scsi_internal_device_block(sdev);
1998 target_block(struct device *dev, void *data)
2000 if (scsi_is_target_device(dev))
2001 starget_for_each_device(to_scsi_target(dev), NULL,
2007 scsi_target_block(struct device *dev)
2009 if (scsi_is_target_device(dev))
2010 starget_for_each_device(to_scsi_target(dev), NULL,
2013 device_for_each_child(dev, NULL, target_block);
2015 EXPORT_SYMBOL_GPL(scsi_target_block);
2018 device_unblock(struct scsi_device *sdev, void *data)
2020 scsi_internal_device_unblock(sdev);
2024 target_unblock(struct device *dev, void *data)
2026 if (scsi_is_target_device(dev))
2027 starget_for_each_device(to_scsi_target(dev), NULL,
2033 scsi_target_unblock(struct device *dev)
2035 if (scsi_is_target_device(dev))
2036 starget_for_each_device(to_scsi_target(dev), NULL,
2039 device_for_each_child(dev, NULL, target_unblock);
2041 EXPORT_SYMBOL_GPL(scsi_target_unblock);