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);
100 static void scsi_release_buffers(struct scsi_cmnd *cmd);
103 * Function: scsi_unprep_request()
105 * Purpose: Remove all preparation done for a request, including its
106 * associated scsi_cmnd, so that it can be requeued.
108 * Arguments: req - request to unprepare
110 * Lock status: Assumed that no locks are held upon entry.
114 static void scsi_unprep_request(struct request *req)
116 struct scsi_cmnd *cmd = req->special;
118 req->flags &= ~REQ_DONTPREP;
119 req->special = (req->flags & REQ_SPECIAL) ? cmd->sc_request : NULL;
121 scsi_release_buffers(cmd);
122 scsi_put_command(cmd);
126 * Function: scsi_queue_insert()
128 * Purpose: Insert a command in the midlevel queue.
130 * Arguments: cmd - command that we are adding to queue.
131 * reason - why we are inserting command to queue.
133 * Lock status: Assumed that lock is not held upon entry.
137 * Notes: We do this for one of two cases. Either the host is busy
138 * and it cannot accept any more commands for the time being,
139 * or the device returned QUEUE_FULL and can accept no more
141 * Notes: This could be called either from an interrupt context or a
142 * normal process context.
143 * Notes: Upon return, cmd is a stale pointer.
145 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
147 struct Scsi_Host *host = cmd->device->host;
148 struct scsi_device *device = cmd->device;
149 struct request_queue *q = device->request_queue;
150 struct request *req = cmd->request;
154 printk("Inserting command %p into mlqueue\n", cmd));
157 * Set the appropriate busy bit for the device/host.
159 * If the host/device isn't busy, assume that something actually
160 * completed, and that we should be able to queue a command now.
162 * Note that the prior mid-layer assumption that any host could
163 * always queue at least one command is now broken. The mid-layer
164 * will implement a user specifiable stall (see
165 * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
166 * if a command is requeued with no other commands outstanding
167 * either for the device or for the host.
169 if (reason == SCSI_MLQUEUE_HOST_BUSY)
170 host->host_blocked = host->max_host_blocked;
171 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
172 device->device_blocked = device->max_device_blocked;
175 * Decrement the counters, since these commands are no longer
176 * active on the host/device.
178 scsi_device_unbusy(device);
181 * Requeue this command. It will go before all other commands
182 * that are already in the queue.
184 * NOTE: there is magic here about the way the queue is plugged if
185 * we have no outstanding commands.
187 * Although we *don't* plug the queue, we call the request
188 * function. The SCSI request function detects the blocked condition
189 * and plugs the queue appropriately.
191 scsi_unprep_request(req);
192 spin_lock_irqsave(q->queue_lock, flags);
193 blk_requeue_request(q, req);
194 spin_unlock_irqrestore(q->queue_lock, flags);
202 * Function: scsi_do_req
204 * Purpose: Queue a SCSI request
206 * Arguments: sreq - command descriptor.
207 * cmnd - actual SCSI command to be performed.
208 * buffer - data buffer.
209 * bufflen - size of data buffer.
210 * done - completion function to be run.
211 * timeout - how long to let it run before timeout.
212 * retries - number of retries we allow.
214 * Lock status: No locks held upon entry.
218 * Notes: This function is only used for queueing requests for things
219 * like ioctls and character device requests - this is because
220 * we essentially just inject a request into the queue for the
223 * In order to support the scsi_device_quiesce function, we
224 * now inject requests on the *head* of the device queue
225 * rather than the tail.
227 void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
228 void *buffer, unsigned bufflen,
229 void (*done)(struct scsi_cmnd *),
230 int timeout, int retries)
233 * If the upper level driver is reusing these things, then
234 * we should release the low-level block now. Another one will
235 * be allocated later when this request is getting queued.
237 __scsi_release_request(sreq);
240 * Our own function scsi_done (which marks the host as not busy,
241 * disables the timeout counter, etc) will be called by us or by the
242 * scsi_hosts[host].queuecommand() function needs to also call
243 * the completion function for the high level driver.
245 memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
246 sreq->sr_bufflen = bufflen;
247 sreq->sr_buffer = buffer;
248 sreq->sr_allowed = retries;
249 sreq->sr_done = done;
250 sreq->sr_timeout_per_command = timeout;
252 if (sreq->sr_cmd_len == 0)
253 sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
256 * head injection *required* here otherwise quiesce won't work
258 scsi_insert_special_req(sreq, 1);
260 EXPORT_SYMBOL(scsi_do_req);
262 /* This is the end routine we get to if a command was never attached
263 * to the request. Simply complete the request without changing
264 * rq_status; this will cause a DRIVER_ERROR. */
265 static void scsi_wait_req_end_io(struct request *req)
267 BUG_ON(!req->waiting);
269 complete(req->waiting);
272 void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
273 unsigned bufflen, int timeout, int retries)
275 DECLARE_COMPLETION(wait);
276 int write = (sreq->sr_data_direction == DMA_TO_DEVICE);
279 req = blk_get_request(sreq->sr_device->request_queue, write,
281 if (bufflen && blk_rq_map_kern(sreq->sr_device->request_queue, req,
282 buffer, bufflen, __GFP_WAIT)) {
283 sreq->sr_result = DRIVER_ERROR << 24;
284 blk_put_request(req);
288 req->flags |= REQ_NOMERGE;
289 req->waiting = &wait;
290 req->end_io = scsi_wait_req_end_io;
291 req->cmd_len = COMMAND_SIZE(((u8 *)cmnd)[0]);
292 req->sense = sreq->sr_sense_buffer;
294 memcpy(req->cmd, cmnd, req->cmd_len);
295 req->timeout = timeout;
296 req->flags |= REQ_BLOCK_PC;
298 blk_insert_request(sreq->sr_device->request_queue, req,
299 sreq->sr_data_direction == DMA_TO_DEVICE, NULL);
300 wait_for_completion(&wait);
301 sreq->sr_request->waiting = NULL;
302 sreq->sr_result = req->errors;
304 sreq->sr_result |= (DRIVER_ERROR << 24);
306 blk_put_request(req);
309 EXPORT_SYMBOL(scsi_wait_req);
312 * scsi_execute - insert request and wait for the result
315 * @data_direction: data direction
316 * @buffer: data buffer
317 * @bufflen: len of buffer
318 * @sense: optional sense buffer
319 * @timeout: request timeout in seconds
320 * @retries: number of times to retry request
321 * @flags: or into request flags;
323 * returns the req->errors value which is the the scsi_cmnd result
326 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
327 int data_direction, void *buffer, unsigned bufflen,
328 unsigned char *sense, int timeout, int retries, int flags)
331 int write = (data_direction == DMA_TO_DEVICE);
332 int ret = DRIVER_ERROR << 24;
334 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
336 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
337 buffer, bufflen, __GFP_WAIT))
340 req->cmd_len = COMMAND_SIZE(cmd[0]);
341 memcpy(req->cmd, cmd, req->cmd_len);
344 req->timeout = timeout;
345 req->flags |= flags | REQ_BLOCK_PC | REQ_SPECIAL | REQ_QUIET;
348 * head injection *required* here otherwise quiesce won't work
350 blk_execute_rq(req->q, NULL, req, 1);
354 blk_put_request(req);
358 EXPORT_SYMBOL(scsi_execute);
361 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
362 int data_direction, void *buffer, unsigned bufflen,
363 struct scsi_sense_hdr *sshdr, int timeout, int retries)
369 sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
371 return DRIVER_ERROR << 24;
372 memset(sense, 0, SCSI_SENSE_BUFFERSIZE);
374 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
375 sense, timeout, retries, 0);
377 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
382 EXPORT_SYMBOL(scsi_execute_req);
385 * Function: scsi_init_cmd_errh()
387 * Purpose: Initialize cmd fields related to error handling.
389 * Arguments: cmd - command that is ready to be queued.
393 * Notes: This function has the job of initializing a number of
394 * fields related to error handling. Typically this will
395 * be called once for each command, as required.
397 static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
399 cmd->serial_number = 0;
401 memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
403 if (cmd->cmd_len == 0)
404 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
407 * We need saved copies of a number of fields - this is because
408 * error handling may need to overwrite these with different values
409 * to run different commands, and once error handling is complete,
410 * we will need to restore these values prior to running the actual
413 cmd->old_use_sg = cmd->use_sg;
414 cmd->old_cmd_len = cmd->cmd_len;
415 cmd->sc_old_data_direction = cmd->sc_data_direction;
416 cmd->old_underflow = cmd->underflow;
417 memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
418 cmd->buffer = cmd->request_buffer;
419 cmd->bufflen = cmd->request_bufflen;
425 * Function: scsi_setup_cmd_retry()
427 * Purpose: Restore the command state for a retry
429 * Arguments: cmd - command to be restored
433 * Notes: Immediately prior to retrying a command, we need
434 * to restore certain fields that we saved above.
436 void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
438 memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
439 cmd->request_buffer = cmd->buffer;
440 cmd->request_bufflen = cmd->bufflen;
441 cmd->use_sg = cmd->old_use_sg;
442 cmd->cmd_len = cmd->old_cmd_len;
443 cmd->sc_data_direction = cmd->sc_old_data_direction;
444 cmd->underflow = cmd->old_underflow;
447 void scsi_device_unbusy(struct scsi_device *sdev)
449 struct Scsi_Host *shost = sdev->host;
452 spin_lock_irqsave(shost->host_lock, flags);
454 if (unlikely((shost->shost_state == SHOST_RECOVERY) &&
456 scsi_eh_wakeup(shost);
457 spin_unlock(shost->host_lock);
458 spin_lock(sdev->request_queue->queue_lock);
460 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
464 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
465 * and call blk_run_queue for all the scsi_devices on the target -
466 * including current_sdev first.
468 * Called with *no* scsi locks held.
470 static void scsi_single_lun_run(struct scsi_device *current_sdev)
472 struct Scsi_Host *shost = current_sdev->host;
473 struct scsi_device *sdev, *tmp;
474 struct scsi_target *starget = scsi_target(current_sdev);
477 spin_lock_irqsave(shost->host_lock, flags);
478 starget->starget_sdev_user = NULL;
479 spin_unlock_irqrestore(shost->host_lock, flags);
482 * Call blk_run_queue for all LUNs on the target, starting with
483 * current_sdev. We race with others (to set starget_sdev_user),
484 * but in most cases, we will be first. Ideally, each LU on the
485 * target would get some limited time or requests on the target.
487 blk_run_queue(current_sdev->request_queue);
489 spin_lock_irqsave(shost->host_lock, flags);
490 if (starget->starget_sdev_user)
492 list_for_each_entry_safe(sdev, tmp, &starget->devices,
493 same_target_siblings) {
494 if (sdev == current_sdev)
496 if (scsi_device_get(sdev))
499 spin_unlock_irqrestore(shost->host_lock, flags);
500 blk_run_queue(sdev->request_queue);
501 spin_lock_irqsave(shost->host_lock, flags);
503 scsi_device_put(sdev);
506 spin_unlock_irqrestore(shost->host_lock, flags);
510 * Function: scsi_run_queue()
512 * Purpose: Select a proper request queue to serve next
514 * Arguments: q - last request's queue
518 * Notes: The previous command was completely finished, start
519 * a new one if possible.
521 static void scsi_run_queue(struct request_queue *q)
523 struct scsi_device *sdev = q->queuedata;
524 struct Scsi_Host *shost = sdev->host;
527 if (sdev->single_lun)
528 scsi_single_lun_run(sdev);
530 spin_lock_irqsave(shost->host_lock, flags);
531 while (!list_empty(&shost->starved_list) &&
532 !shost->host_blocked && !shost->host_self_blocked &&
533 !((shost->can_queue > 0) &&
534 (shost->host_busy >= shost->can_queue))) {
536 * As long as shost is accepting commands and we have
537 * starved queues, call blk_run_queue. scsi_request_fn
538 * drops the queue_lock and can add us back to the
541 * host_lock protects the starved_list and starved_entry.
542 * scsi_request_fn must get the host_lock before checking
543 * or modifying starved_list or starved_entry.
545 sdev = list_entry(shost->starved_list.next,
546 struct scsi_device, starved_entry);
547 list_del_init(&sdev->starved_entry);
548 spin_unlock_irqrestore(shost->host_lock, flags);
550 blk_run_queue(sdev->request_queue);
552 spin_lock_irqsave(shost->host_lock, flags);
553 if (unlikely(!list_empty(&sdev->starved_entry)))
555 * sdev lost a race, and was put back on the
556 * starved list. This is unlikely but without this
557 * in theory we could loop forever.
561 spin_unlock_irqrestore(shost->host_lock, flags);
567 * Function: scsi_requeue_command()
569 * Purpose: Handle post-processing of completed commands.
571 * Arguments: q - queue to operate on
572 * cmd - command that may need to be requeued.
576 * Notes: After command completion, there may be blocks left
577 * over which weren't finished by the previous command
578 * this can be for a number of reasons - the main one is
579 * I/O errors in the middle of the request, in which case
580 * we need to request the blocks that come after the bad
582 * Notes: Upon return, cmd is a stale pointer.
584 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
586 struct request *req = cmd->request;
589 scsi_unprep_request(req);
590 spin_lock_irqsave(q->queue_lock, flags);
591 blk_requeue_request(q, req);
592 spin_unlock_irqrestore(q->queue_lock, flags);
597 void scsi_next_command(struct scsi_cmnd *cmd)
599 struct request_queue *q = cmd->device->request_queue;
601 scsi_put_command(cmd);
605 void scsi_run_host_queues(struct Scsi_Host *shost)
607 struct scsi_device *sdev;
609 shost_for_each_device(sdev, shost)
610 scsi_run_queue(sdev->request_queue);
614 * Function: scsi_end_request()
616 * Purpose: Post-processing of completed commands (usually invoked at end
617 * of upper level post-processing and scsi_io_completion).
619 * Arguments: cmd - command that is complete.
620 * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
621 * bytes - number of bytes of completed I/O
622 * requeue - indicates whether we should requeue leftovers.
624 * Lock status: Assumed that lock is not held upon entry.
626 * Returns: cmd if requeue required, NULL otherwise.
628 * Notes: This is called for block device requests in order to
629 * mark some number of sectors as complete.
631 * We are guaranteeing that the request queue will be goosed
632 * at some point during this call.
633 * Notes: If cmd was requeued, upon return it will be a stale pointer.
635 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
636 int bytes, int requeue)
638 request_queue_t *q = cmd->device->request_queue;
639 struct request *req = cmd->request;
643 * If there are blocks left over at the end, set up the command
644 * to queue the remainder of them.
646 if (end_that_request_chunk(req, uptodate, bytes)) {
647 int leftover = (req->hard_nr_sectors << 9);
649 if (blk_pc_request(req))
650 leftover = req->data_len;
652 /* kill remainder if no retrys */
653 if (!uptodate && blk_noretry_request(req))
654 end_that_request_chunk(req, 0, leftover);
658 * Bleah. Leftovers again. Stick the
659 * leftovers in the front of the
660 * queue, and goose the queue again.
662 scsi_requeue_command(q, cmd);
669 add_disk_randomness(req->rq_disk);
671 spin_lock_irqsave(q->queue_lock, flags);
672 if (blk_rq_tagged(req))
673 blk_queue_end_tag(q, req);
674 end_that_request_last(req);
675 spin_unlock_irqrestore(q->queue_lock, flags);
678 * This will goose the queue request function at the end, so we don't
679 * need to worry about launching another command.
681 scsi_next_command(cmd);
685 static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
687 struct scsi_host_sg_pool *sgp;
688 struct scatterlist *sgl;
690 BUG_ON(!cmd->use_sg);
692 switch (cmd->use_sg) {
702 #if (SCSI_MAX_PHYS_SEGMENTS > 32)
706 #if (SCSI_MAX_PHYS_SEGMENTS > 64)
710 #if (SCSI_MAX_PHYS_SEGMENTS > 128)
721 sgp = scsi_sg_pools + cmd->sglist_len;
722 sgl = mempool_alloc(sgp->pool, gfp_mask);
726 static void scsi_free_sgtable(struct scatterlist *sgl, int index)
728 struct scsi_host_sg_pool *sgp;
730 BUG_ON(index >= SG_MEMPOOL_NR);
732 sgp = scsi_sg_pools + index;
733 mempool_free(sgl, sgp->pool);
737 * Function: scsi_release_buffers()
739 * Purpose: Completion processing for block device I/O requests.
741 * Arguments: cmd - command that we are bailing.
743 * Lock status: Assumed that no lock is held upon entry.
747 * Notes: In the event that an upper level driver rejects a
748 * command, we must release resources allocated during
749 * the __init_io() function. Primarily this would involve
750 * the scatter-gather table, and potentially any bounce
753 static void scsi_release_buffers(struct scsi_cmnd *cmd)
755 struct request *req = cmd->request;
758 * Free up any indirection buffers we allocated for DMA purposes.
761 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
762 else if (cmd->request_buffer != req->buffer)
763 kfree(cmd->request_buffer);
766 * Zero these out. They now point to freed memory, and it is
767 * dangerous to hang onto the pointers.
771 cmd->request_buffer = NULL;
772 cmd->request_bufflen = 0;
776 * Function: scsi_io_completion()
778 * Purpose: Completion processing for block device I/O requests.
780 * Arguments: cmd - command that is finished.
782 * Lock status: Assumed that no lock is held upon entry.
786 * Notes: This function is matched in terms of capabilities to
787 * the function that created the scatter-gather list.
788 * In other words, if there are no bounce buffers
789 * (the normal case for most drivers), we don't need
790 * the logic to deal with cleaning up afterwards.
792 * We must do one of several things here:
794 * a) Call scsi_end_request. This will finish off the
795 * specified number of sectors. If we are done, the
796 * command block will be released, and the queue
797 * function will be goosed. If we are not done, then
798 * scsi_end_request will directly goose the queue.
800 * b) We can just use scsi_requeue_command() here. This would
801 * be used if we just wanted to retry, for example.
803 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
804 unsigned int block_bytes)
806 int result = cmd->result;
807 int this_count = cmd->bufflen;
808 request_queue_t *q = cmd->device->request_queue;
809 struct request *req = cmd->request;
810 int clear_errors = 1;
811 struct scsi_sense_hdr sshdr;
813 int sense_deferred = 0;
815 if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
819 * Free up any indirection buffers we allocated for DMA purposes.
820 * For the case of a READ, we need to copy the data out of the
821 * bounce buffer and into the real buffer.
824 scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
825 else if (cmd->buffer != req->buffer) {
826 if (rq_data_dir(req) == READ) {
828 char *to = bio_kmap_irq(req->bio, &flags);
829 memcpy(to, cmd->buffer, cmd->bufflen);
830 bio_kunmap_irq(to, &flags);
836 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
838 sense_deferred = scsi_sense_is_deferred(&sshdr);
840 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
841 req->errors = result;
844 if (sense_valid && req->sense) {
846 * SG_IO wants current and deferred errors
848 int len = 8 + cmd->sense_buffer[7];
850 if (len > SCSI_SENSE_BUFFERSIZE)
851 len = SCSI_SENSE_BUFFERSIZE;
852 memcpy(req->sense, cmd->sense_buffer, len);
853 req->sense_len = len;
856 req->data_len = cmd->resid;
860 * Zero these out. They now point to freed memory, and it is
861 * dangerous to hang onto the pointers.
865 cmd->request_buffer = NULL;
866 cmd->request_bufflen = 0;
869 * Next deal with any sectors which we were able to correctly
872 if (good_bytes >= 0) {
873 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
874 req->nr_sectors, good_bytes));
875 SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
880 * If multiple sectors are requested in one buffer, then
881 * they will have been finished off by the first command.
882 * If not, then we have a multi-buffer command.
884 * If block_bytes != 0, it means we had a medium error
885 * of some sort, and that we want to mark some number of
886 * sectors as not uptodate. Thus we want to inhibit
887 * requeueing right here - we will requeue down below
888 * when we handle the bad sectors.
892 * If the command completed without error, then either
893 * finish off the rest of the command, or start a new one.
895 if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
899 * Now, if we were good little boys and girls, Santa left us a request
900 * sense buffer. We can extract information from this, so we
901 * can choose a block to remap, etc.
903 if (sense_valid && !sense_deferred) {
904 switch (sshdr.sense_key) {
906 if (cmd->device->removable) {
907 /* detected disc change. set a bit
908 * and quietly refuse further access.
910 cmd->device->changed = 1;
911 scsi_end_request(cmd, 0,
916 * Must have been a power glitch, or a
917 * bus reset. Could not have been a
918 * media change, so we just retry the
919 * request and see what happens.
921 scsi_requeue_command(q, cmd);
925 case ILLEGAL_REQUEST:
927 * If we had an ILLEGAL REQUEST returned, then we may
928 * have performed an unsupported command. The only
929 * thing this should be would be a ten byte read where
930 * only a six byte read was supported. Also, on a
931 * system where READ CAPACITY failed, we may have read
932 * past the end of the disk.
934 if (cmd->device->use_10_for_rw &&
935 (cmd->cmnd[0] == READ_10 ||
936 cmd->cmnd[0] == WRITE_10)) {
937 cmd->device->use_10_for_rw = 0;
939 * This will cause a retry with a 6-byte
942 scsi_requeue_command(q, cmd);
945 scsi_end_request(cmd, 0, this_count, 1);
951 * If the device is in the process of becoming ready,
954 if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
955 scsi_requeue_command(q, cmd);
958 if (!(req->flags & REQ_QUIET))
959 dev_printk(KERN_INFO,
960 &cmd->device->sdev_gendev,
961 "Device not ready.\n");
962 scsi_end_request(cmd, 0, this_count, 1);
964 case VOLUME_OVERFLOW:
965 if (!(req->flags & REQ_QUIET)) {
966 dev_printk(KERN_INFO,
967 &cmd->device->sdev_gendev,
968 "Volume overflow, CDB: ");
969 __scsi_print_command(cmd->data_cmnd);
970 scsi_print_sense("", cmd);
972 scsi_end_request(cmd, 0, block_bytes, 1);
977 } /* driver byte != 0 */
978 if (host_byte(result) == DID_RESET) {
980 * Third party bus reset or reset for error
981 * recovery reasons. Just retry the request
982 * and see what happens.
984 scsi_requeue_command(q, cmd);
988 if (!(req->flags & REQ_QUIET)) {
989 dev_printk(KERN_INFO, &cmd->device->sdev_gendev,
990 "SCSI error: return code = 0x%x\n", result);
992 if (driver_byte(result) & DRIVER_SENSE)
993 scsi_print_sense("", cmd);
996 * Mark a single buffer as not uptodate. Queue the remainder.
997 * We sometimes get this cruft in the event that a medium error
998 * isn't properly reported.
1000 block_bytes = req->hard_cur_sectors << 9;
1002 block_bytes = req->data_len;
1003 scsi_end_request(cmd, 0, block_bytes, 1);
1006 EXPORT_SYMBOL(scsi_io_completion);
1009 * Function: scsi_init_io()
1011 * Purpose: SCSI I/O initialize function.
1013 * Arguments: cmd - Command descriptor we wish to initialize
1015 * Returns: 0 on success
1016 * BLKPREP_DEFER if the failure is retryable
1017 * BLKPREP_KILL if the failure is fatal
1019 static int scsi_init_io(struct scsi_cmnd *cmd)
1021 struct request *req = cmd->request;
1022 struct scatterlist *sgpnt;
1026 * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
1028 if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
1029 cmd->request_bufflen = req->data_len;
1030 cmd->request_buffer = req->data;
1031 req->buffer = req->data;
1037 * we used to not use scatter-gather for single segment request,
1038 * but now we do (it makes highmem I/O easier to support without
1041 cmd->use_sg = req->nr_phys_segments;
1044 * if sg table allocation fails, requeue request later.
1046 sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
1047 if (unlikely(!sgpnt))
1048 return BLKPREP_DEFER;
1050 cmd->request_buffer = (char *) sgpnt;
1051 cmd->request_bufflen = req->nr_sectors << 9;
1052 if (blk_pc_request(req))
1053 cmd->request_bufflen = req->data_len;
1057 * Next, walk the list, and fill in the addresses and sizes of
1060 count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
1063 * mapped well, send it off
1065 if (likely(count <= cmd->use_sg)) {
1066 cmd->use_sg = count;
1070 printk(KERN_ERR "Incorrect number of segments after building list\n");
1071 printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
1072 printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
1073 req->current_nr_sectors);
1075 /* release the command and kill it */
1076 scsi_release_buffers(cmd);
1077 scsi_put_command(cmd);
1078 return BLKPREP_KILL;
1081 static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
1083 struct scsi_device *sdev = q->queuedata;
1084 struct scsi_driver *drv;
1086 if (sdev->sdev_state == SDEV_RUNNING) {
1087 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1089 if (drv->prepare_flush)
1090 return drv->prepare_flush(q, rq);
1096 static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
1098 struct scsi_device *sdev = q->queuedata;
1099 struct request *flush_rq = rq->end_io_data;
1100 struct scsi_driver *drv;
1102 if (flush_rq->errors) {
1103 printk("scsi: barrier error, disabling flush support\n");
1104 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1107 if (sdev->sdev_state == SDEV_RUNNING) {
1108 drv = *(struct scsi_driver **) rq->rq_disk->private_data;
1109 drv->end_flush(q, rq);
1113 static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
1114 sector_t *error_sector)
1116 struct scsi_device *sdev = q->queuedata;
1117 struct scsi_driver *drv;
1119 if (sdev->sdev_state != SDEV_RUNNING)
1122 drv = *(struct scsi_driver **) disk->private_data;
1123 if (drv->issue_flush)
1124 return drv->issue_flush(&sdev->sdev_gendev, error_sector);
1129 static void scsi_generic_done(struct scsi_cmnd *cmd)
1131 BUG_ON(!blk_pc_request(cmd->request));
1132 scsi_io_completion(cmd, cmd->result == 0 ? cmd->bufflen : 0, 0);
1135 static int scsi_prep_fn(struct request_queue *q, struct request *req)
1137 struct scsi_device *sdev = q->queuedata;
1138 struct scsi_cmnd *cmd;
1139 int specials_only = 0;
1142 * Just check to see if the device is online. If it isn't, we
1143 * refuse to process any commands. The device must be brought
1144 * online before trying any recovery commands
1146 if (unlikely(!scsi_device_online(sdev))) {
1147 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1148 sdev->host->host_no, sdev->id, sdev->lun);
1151 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1152 /* OK, we're not in a running state don't prep
1154 if (sdev->sdev_state == SDEV_DEL) {
1155 /* Device is fully deleted, no commands
1156 * at all allowed down */
1157 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
1158 sdev->host->host_no, sdev->id, sdev->lun);
1161 /* OK, we only allow special commands (i.e. not
1162 * user initiated ones */
1163 specials_only = sdev->sdev_state;
1167 * Find the actual device driver associated with this command.
1168 * The SPECIAL requests are things like character device or
1169 * ioctls, which did not originate from ll_rw_blk. Note that
1170 * the special field is also used to indicate the cmd for
1171 * the remainder of a partially fulfilled request that can
1172 * come up when there is a medium error. We have to treat
1173 * these two cases differently. We differentiate by looking
1174 * at request->cmd, as this tells us the real story.
1176 if (req->flags & REQ_SPECIAL && req->special) {
1177 struct scsi_request *sreq = req->special;
1179 if (sreq->sr_magic == SCSI_REQ_MAGIC) {
1180 cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
1183 scsi_init_cmd_from_req(cmd, sreq);
1186 } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1188 if(unlikely(specials_only) && !(req->flags & REQ_SPECIAL)) {
1189 if(specials_only == SDEV_QUIESCE ||
1190 specials_only == SDEV_BLOCK)
1193 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
1194 sdev->host->host_no, sdev->id, sdev->lun);
1200 * Now try and find a command block that we can use.
1202 if (!req->special) {
1203 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1209 /* pull a tag out of the request if we have one */
1210 cmd->tag = req->tag;
1212 blk_dump_rq_flags(req, "SCSI bad req");
1216 /* note the overloading of req->special. When the tag
1217 * is active it always means cmd. If the tag goes
1218 * back for re-queueing, it may be reset */
1223 * FIXME: drop the lock here because the functions below
1224 * expect to be called without the queue lock held. Also,
1225 * previously, we dequeued the request before dropping the
1226 * lock. We hope REQ_STARTED prevents anything untoward from
1229 if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
1230 struct scsi_driver *drv;
1234 * This will do a couple of things:
1235 * 1) Fill in the actual SCSI command.
1236 * 2) Fill in any other upper-level specific fields
1239 * If this returns 0, it means that the request failed
1240 * (reading past end of disk, reading offline device,
1241 * etc). This won't actually talk to the device, but
1242 * some kinds of consistency checking may cause the
1243 * request to be rejected immediately.
1247 * This sets up the scatter-gather table (allocating if
1250 ret = scsi_init_io(cmd);
1253 /* BLKPREP_KILL return also releases the command */
1260 * Initialize the actual SCSI command for this request.
1263 drv = *(struct scsi_driver **)req->rq_disk->private_data;
1264 if (unlikely(!drv->init_command(cmd))) {
1265 scsi_release_buffers(cmd);
1266 scsi_put_command(cmd);
1270 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
1271 cmd->cmd_len = req->cmd_len;
1272 if (rq_data_dir(req) == WRITE)
1273 cmd->sc_data_direction = DMA_TO_DEVICE;
1274 else if (req->data_len)
1275 cmd->sc_data_direction = DMA_FROM_DEVICE;
1277 cmd->sc_data_direction = DMA_NONE;
1279 cmd->transfersize = req->data_len;
1281 cmd->timeout_per_command = req->timeout;
1282 cmd->done = scsi_generic_done;
1287 * The request is now prepped, no need to come back here
1289 req->flags |= REQ_DONTPREP;
1293 /* If we defer, the elv_next_request() returns NULL, but the
1294 * queue must be restarted, so we plug here if no returning
1295 * command will automatically do that. */
1296 if (sdev->device_busy == 0)
1298 return BLKPREP_DEFER;
1300 req->errors = DID_NO_CONNECT << 16;
1301 return BLKPREP_KILL;
1305 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1308 * Called with the queue_lock held.
1310 static inline int scsi_dev_queue_ready(struct request_queue *q,
1311 struct scsi_device *sdev)
1313 if (sdev->device_busy >= sdev->queue_depth)
1315 if (sdev->device_busy == 0 && sdev->device_blocked) {
1317 * unblock after device_blocked iterates to zero
1319 if (--sdev->device_blocked == 0) {
1321 printk("scsi%d (%d:%d) unblocking device at"
1322 " zero depth\n", sdev->host->host_no,
1323 sdev->id, sdev->lun));
1329 if (sdev->device_blocked)
1336 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1337 * return 0. We must end up running the queue again whenever 0 is
1338 * returned, else IO can hang.
1340 * Called with host_lock held.
1342 static inline int scsi_host_queue_ready(struct request_queue *q,
1343 struct Scsi_Host *shost,
1344 struct scsi_device *sdev)
1346 if (shost->shost_state == SHOST_RECOVERY)
1348 if (shost->host_busy == 0 && shost->host_blocked) {
1350 * unblock after host_blocked iterates to zero
1352 if (--shost->host_blocked == 0) {
1354 printk("scsi%d unblocking host at zero depth\n",
1361 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
1362 shost->host_blocked || shost->host_self_blocked) {
1363 if (list_empty(&sdev->starved_entry))
1364 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1368 /* We're OK to process the command, so we can't be starved */
1369 if (!list_empty(&sdev->starved_entry))
1370 list_del_init(&sdev->starved_entry);
1376 * Kill a request for a dead device
1378 static void scsi_kill_request(struct request *req, request_queue_t *q)
1380 struct scsi_cmnd *cmd = req->special;
1382 blkdev_dequeue_request(req);
1384 if (unlikely(cmd == NULL)) {
1385 printk(KERN_CRIT "impossible request in %s.\n",
1390 scsi_init_cmd_errh(cmd);
1391 cmd->result = DID_NO_CONNECT << 16;
1392 atomic_inc(&cmd->device->iorequest_cnt);
1397 * Function: scsi_request_fn()
1399 * Purpose: Main strategy routine for SCSI.
1401 * Arguments: q - Pointer to actual queue.
1405 * Lock status: IO request lock assumed to be held when called.
1407 static void scsi_request_fn(struct request_queue *q)
1409 struct scsi_device *sdev = q->queuedata;
1410 struct Scsi_Host *shost;
1411 struct scsi_cmnd *cmd;
1412 struct request *req;
1415 printk("scsi: killing requests for dead queue\n");
1416 while ((req = elv_next_request(q)) != NULL)
1417 scsi_kill_request(req, q);
1421 if(!get_device(&sdev->sdev_gendev))
1422 /* We must be tearing the block queue down already */
1426 * To start with, we keep looping until the queue is empty, or until
1427 * the host is no longer able to accept any more requests.
1430 while (!blk_queue_plugged(q)) {
1433 * get next queueable request. We do this early to make sure
1434 * that the request is fully prepared even if we cannot
1437 req = elv_next_request(q);
1438 if (!req || !scsi_dev_queue_ready(q, sdev))
1441 if (unlikely(!scsi_device_online(sdev))) {
1442 printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
1443 sdev->host->host_no, sdev->id, sdev->lun);
1444 scsi_kill_request(req, q);
1450 * Remove the request from the request list.
1452 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1453 blkdev_dequeue_request(req);
1454 sdev->device_busy++;
1456 spin_unlock(q->queue_lock);
1458 if (unlikely(cmd == NULL)) {
1459 printk(KERN_CRIT "impossible request in %s.\n"
1460 "please mail a stack trace to "
1461 "linux-scsi@vger.kernel.org",
1465 spin_lock(shost->host_lock);
1467 if (!scsi_host_queue_ready(q, shost, sdev))
1469 if (sdev->single_lun) {
1470 if (scsi_target(sdev)->starget_sdev_user &&
1471 scsi_target(sdev)->starget_sdev_user != sdev)
1473 scsi_target(sdev)->starget_sdev_user = sdev;
1478 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1479 * take the lock again.
1481 spin_unlock_irq(shost->host_lock);
1484 * Finally, initialize any error handling parameters, and set up
1485 * the timers for timeouts.
1487 scsi_init_cmd_errh(cmd);
1490 * Dispatch the command to the low-level driver.
1492 rtn = scsi_dispatch_cmd(cmd);
1493 spin_lock_irq(q->queue_lock);
1495 /* we're refusing the command; because of
1496 * the way locks get dropped, we need to
1497 * check here if plugging is required */
1498 if(sdev->device_busy == 0)
1508 spin_unlock_irq(shost->host_lock);
1511 * lock q, handle tag, requeue req, and decrement device_busy. We
1512 * must return with queue_lock held.
1514 * Decrementing device_busy without checking it is OK, as all such
1515 * cases (host limits or settings) should run the queue at some
1518 scsi_unprep_request(req);
1519 spin_lock_irq(q->queue_lock);
1520 blk_requeue_request(q, req);
1521 sdev->device_busy--;
1522 if(sdev->device_busy == 0)
1525 /* must be careful here...if we trigger the ->remove() function
1526 * we cannot be holding the q lock */
1527 spin_unlock_irq(q->queue_lock);
1528 put_device(&sdev->sdev_gendev);
1529 spin_lock_irq(q->queue_lock);
1532 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1534 struct device *host_dev;
1535 u64 bounce_limit = 0xffffffff;
1537 if (shost->unchecked_isa_dma)
1538 return BLK_BOUNCE_ISA;
1540 * Platforms with virtual-DMA translation
1541 * hardware have no practical limit.
1543 if (!PCI_DMA_BUS_IS_PHYS)
1544 return BLK_BOUNCE_ANY;
1546 host_dev = scsi_get_device(shost);
1547 if (host_dev && host_dev->dma_mask)
1548 bounce_limit = *host_dev->dma_mask;
1550 return bounce_limit;
1552 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1554 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1556 struct Scsi_Host *shost = sdev->host;
1557 struct request_queue *q;
1559 q = blk_init_queue(scsi_request_fn, NULL);
1563 blk_queue_prep_rq(q, scsi_prep_fn);
1565 blk_queue_max_hw_segments(q, shost->sg_tablesize);
1566 blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
1567 blk_queue_max_sectors(q, shost->max_sectors);
1568 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1569 blk_queue_segment_boundary(q, shost->dma_boundary);
1570 blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
1573 * ordered tags are superior to flush ordering
1575 if (shost->ordered_tag)
1576 blk_queue_ordered(q, QUEUE_ORDERED_TAG);
1577 else if (shost->ordered_flush) {
1578 blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
1579 q->prepare_flush_fn = scsi_prepare_flush_fn;
1580 q->end_flush_fn = scsi_end_flush_fn;
1583 if (!shost->use_clustering)
1584 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
1588 void scsi_free_queue(struct request_queue *q)
1590 blk_cleanup_queue(q);
1594 * Function: scsi_block_requests()
1596 * Purpose: Utility function used by low-level drivers to prevent further
1597 * commands from being queued to the device.
1599 * Arguments: shost - Host in question
1603 * Lock status: No locks are assumed held.
1605 * Notes: There is no timer nor any other means by which the requests
1606 * get unblocked other than the low-level driver calling
1607 * scsi_unblock_requests().
1609 void scsi_block_requests(struct Scsi_Host *shost)
1611 shost->host_self_blocked = 1;
1613 EXPORT_SYMBOL(scsi_block_requests);
1616 * Function: scsi_unblock_requests()
1618 * Purpose: Utility function used by low-level drivers to allow further
1619 * commands from being queued to the device.
1621 * Arguments: shost - Host in question
1625 * Lock status: No locks are assumed held.
1627 * Notes: There is no timer nor any other means by which the requests
1628 * get unblocked other than the low-level driver calling
1629 * scsi_unblock_requests().
1631 * This is done as an API function so that changes to the
1632 * internals of the scsi mid-layer won't require wholesale
1633 * changes to drivers that use this feature.
1635 void scsi_unblock_requests(struct Scsi_Host *shost)
1637 shost->host_self_blocked = 0;
1638 scsi_run_host_queues(shost);
1640 EXPORT_SYMBOL(scsi_unblock_requests);
1642 int __init scsi_init_queue(void)
1646 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1647 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1648 int size = sgp->size * sizeof(struct scatterlist);
1650 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1651 SLAB_HWCACHE_ALIGN, NULL, NULL);
1653 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1657 sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
1658 mempool_alloc_slab, mempool_free_slab,
1661 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1669 void scsi_exit_queue(void)
1673 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1674 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1675 mempool_destroy(sgp->pool);
1676 kmem_cache_destroy(sgp->slab);
1680 * scsi_mode_sense - issue a mode sense, falling back from 10 to
1681 * six bytes if necessary.
1682 * @sdev: SCSI device to be queried
1683 * @dbd: set if mode sense will allow block descriptors to be returned
1684 * @modepage: mode page being requested
1685 * @buffer: request buffer (may not be smaller than eight bytes)
1686 * @len: length of request buffer.
1687 * @timeout: command timeout
1688 * @retries: number of retries before failing
1689 * @data: returns a structure abstracting the mode header data
1690 * @sense: place to put sense data (or NULL if no sense to be collected).
1691 * must be SCSI_SENSE_BUFFERSIZE big.
1693 * Returns zero if unsuccessful, or the header offset (either 4
1694 * or 8 depending on whether a six or ten byte command was
1695 * issued) if successful.
1698 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1699 unsigned char *buffer, int len, int timeout, int retries,
1700 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) {
1701 unsigned char cmd[12];
1705 struct scsi_sense_hdr my_sshdr;
1707 memset(data, 0, sizeof(*data));
1708 memset(&cmd[0], 0, 12);
1709 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1712 /* caller might not be interested in sense, but we need it */
1717 use_10_for_ms = sdev->use_10_for_ms;
1719 if (use_10_for_ms) {
1723 cmd[0] = MODE_SENSE_10;
1730 cmd[0] = MODE_SENSE;
1735 memset(buffer, 0, len);
1737 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1738 sshdr, timeout, retries);
1740 /* This code looks awful: what it's doing is making sure an
1741 * ILLEGAL REQUEST sense return identifies the actual command
1742 * byte as the problem. MODE_SENSE commands can return
1743 * ILLEGAL REQUEST if the code page isn't supported */
1745 if (use_10_for_ms && !scsi_status_is_good(result) &&
1746 (driver_byte(result) & DRIVER_SENSE)) {
1747 if (scsi_sense_valid(sshdr)) {
1748 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1749 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1751 * Invalid command operation code
1753 sdev->use_10_for_ms = 0;
1759 if(scsi_status_is_good(result)) {
1760 data->header_length = header_length;
1762 data->length = buffer[0]*256 + buffer[1] + 2;
1763 data->medium_type = buffer[2];
1764 data->device_specific = buffer[3];
1765 data->longlba = buffer[4] & 0x01;
1766 data->block_descriptor_length = buffer[6]*256
1769 data->length = buffer[0] + 1;
1770 data->medium_type = buffer[1];
1771 data->device_specific = buffer[2];
1772 data->block_descriptor_length = buffer[3];
1778 EXPORT_SYMBOL(scsi_mode_sense);
1781 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
1784 TEST_UNIT_READY, 0, 0, 0, 0, 0,
1786 struct scsi_sense_hdr sshdr;
1789 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
1792 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
1794 if ((scsi_sense_valid(&sshdr)) &&
1795 ((sshdr.sense_key == UNIT_ATTENTION) ||
1796 (sshdr.sense_key == NOT_READY))) {
1803 EXPORT_SYMBOL(scsi_test_unit_ready);
1806 * scsi_device_set_state - Take the given device through the device
1808 * @sdev: scsi device to change the state of.
1809 * @state: state to change to.
1811 * Returns zero if unsuccessful or an error if the requested
1812 * transition is illegal.
1815 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
1817 enum scsi_device_state oldstate = sdev->sdev_state;
1819 if (state == oldstate)
1824 /* There are no legal states that come back to
1825 * created. This is the manually initialised start
1895 sdev->sdev_state = state;
1899 SCSI_LOG_ERROR_RECOVERY(1,
1900 dev_printk(KERN_ERR, &sdev->sdev_gendev,
1901 "Illegal state transition %s->%s\n",
1902 scsi_device_state_name(oldstate),
1903 scsi_device_state_name(state))
1907 EXPORT_SYMBOL(scsi_device_set_state);
1910 * scsi_device_quiesce - Block user issued commands.
1911 * @sdev: scsi device to quiesce.
1913 * This works by trying to transition to the SDEV_QUIESCE state
1914 * (which must be a legal transition). When the device is in this
1915 * state, only special requests will be accepted, all others will
1916 * be deferred. Since special requests may also be requeued requests,
1917 * a successful return doesn't guarantee the device will be
1918 * totally quiescent.
1920 * Must be called with user context, may sleep.
1922 * Returns zero if unsuccessful or an error if not.
1925 scsi_device_quiesce(struct scsi_device *sdev)
1927 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
1931 scsi_run_queue(sdev->request_queue);
1932 while (sdev->device_busy) {
1933 msleep_interruptible(200);
1934 scsi_run_queue(sdev->request_queue);
1938 EXPORT_SYMBOL(scsi_device_quiesce);
1941 * scsi_device_resume - Restart user issued commands to a quiesced device.
1942 * @sdev: scsi device to resume.
1944 * Moves the device from quiesced back to running and restarts the
1947 * Must be called with user context, may sleep.
1950 scsi_device_resume(struct scsi_device *sdev)
1952 if(scsi_device_set_state(sdev, SDEV_RUNNING))
1954 scsi_run_queue(sdev->request_queue);
1956 EXPORT_SYMBOL(scsi_device_resume);
1959 device_quiesce_fn(struct scsi_device *sdev, void *data)
1961 scsi_device_quiesce(sdev);
1965 scsi_target_quiesce(struct scsi_target *starget)
1967 starget_for_each_device(starget, NULL, device_quiesce_fn);
1969 EXPORT_SYMBOL(scsi_target_quiesce);
1972 device_resume_fn(struct scsi_device *sdev, void *data)
1974 scsi_device_resume(sdev);
1978 scsi_target_resume(struct scsi_target *starget)
1980 starget_for_each_device(starget, NULL, device_resume_fn);
1982 EXPORT_SYMBOL(scsi_target_resume);
1985 * scsi_internal_device_block - internal function to put a device
1986 * temporarily into the SDEV_BLOCK state
1987 * @sdev: device to block
1989 * Block request made by scsi lld's to temporarily stop all
1990 * scsi commands on the specified device. Called from interrupt
1991 * or normal process context.
1993 * Returns zero if successful or error if not
1996 * This routine transitions the device to the SDEV_BLOCK state
1997 * (which must be a legal transition). When the device is in this
1998 * state, all commands are deferred until the scsi lld reenables
1999 * the device with scsi_device_unblock or device_block_tmo fires.
2000 * This routine assumes the host_lock is held on entry.
2003 scsi_internal_device_block(struct scsi_device *sdev)
2005 request_queue_t *q = sdev->request_queue;
2006 unsigned long flags;
2009 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2014 * The device has transitioned to SDEV_BLOCK. Stop the
2015 * block layer from calling the midlayer with this device's
2018 spin_lock_irqsave(q->queue_lock, flags);
2020 spin_unlock_irqrestore(q->queue_lock, flags);
2024 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2027 * scsi_internal_device_unblock - resume a device after a block request
2028 * @sdev: device to resume
2030 * Called by scsi lld's or the midlayer to restart the device queue
2031 * for the previously suspended scsi device. Called from interrupt or
2032 * normal process context.
2034 * Returns zero if successful or error if not.
2037 * This routine transitions the device to the SDEV_RUNNING state
2038 * (which must be a legal transition) allowing the midlayer to
2039 * goose the queue for this device. This routine assumes the
2040 * host_lock is held upon entry.
2043 scsi_internal_device_unblock(struct scsi_device *sdev)
2045 request_queue_t *q = sdev->request_queue;
2047 unsigned long flags;
2050 * Try to transition the scsi device to SDEV_RUNNING
2051 * and goose the device queue if successful.
2053 err = scsi_device_set_state(sdev, SDEV_RUNNING);
2057 spin_lock_irqsave(q->queue_lock, flags);
2059 spin_unlock_irqrestore(q->queue_lock, flags);
2063 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2066 device_block(struct scsi_device *sdev, void *data)
2068 scsi_internal_device_block(sdev);
2072 target_block(struct device *dev, void *data)
2074 if (scsi_is_target_device(dev))
2075 starget_for_each_device(to_scsi_target(dev), NULL,
2081 scsi_target_block(struct device *dev)
2083 if (scsi_is_target_device(dev))
2084 starget_for_each_device(to_scsi_target(dev), NULL,
2087 device_for_each_child(dev, NULL, target_block);
2089 EXPORT_SYMBOL_GPL(scsi_target_block);
2092 device_unblock(struct scsi_device *sdev, void *data)
2094 scsi_internal_device_unblock(sdev);
2098 target_unblock(struct device *dev, void *data)
2100 if (scsi_is_target_device(dev))
2101 starget_for_each_device(to_scsi_target(dev), NULL,
2107 scsi_target_unblock(struct device *dev)
2109 if (scsi_is_target_device(dev))
2110 starget_for_each_device(to_scsi_target(dev), NULL,
2113 device_for_each_child(dev, NULL, target_unblock);
2115 EXPORT_SYMBOL_GPL(scsi_target_unblock);