config: tegra3: enable /dev mount with ACL
[linux-2.6.git] / drivers / scsi / scsi_lib.c
1 /*
2  *  scsi_lib.c Copyright (C) 1999 Eric Youngdale
3  *
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.
8  */
9
10 #include <linux/bio.h>
11 #include <linux/bitops.h>
12 #include <linux/blkdev.h>
13 #include <linux/completion.h>
14 #include <linux/kernel.h>
15 #include <linux/mempool.h>
16 #include <linux/slab.h>
17 #include <linux/init.h>
18 #include <linux/pci.h>
19 #include <linux/delay.h>
20 #include <linux/hardirq.h>
21 #include <linux/scatterlist.h>
22
23 #include <scsi/scsi.h>
24 #include <scsi/scsi_cmnd.h>
25 #include <scsi/scsi_dbg.h>
26 #include <scsi/scsi_device.h>
27 #include <scsi/scsi_driver.h>
28 #include <scsi/scsi_eh.h>
29 #include <scsi/scsi_host.h>
30
31 #include "scsi_priv.h"
32 #include "scsi_logging.h"
33
34
35 #define SG_MEMPOOL_NR           ARRAY_SIZE(scsi_sg_pools)
36 #define SG_MEMPOOL_SIZE         2
37
38 struct scsi_host_sg_pool {
39         size_t          size;
40         char            *name;
41         struct kmem_cache       *slab;
42         mempool_t       *pool;
43 };
44
45 #define SP(x) { x, "sgpool-" __stringify(x) }
46 #if (SCSI_MAX_SG_SEGMENTS < 32)
47 #error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
48 #endif
49 static struct scsi_host_sg_pool scsi_sg_pools[] = {
50         SP(8),
51         SP(16),
52 #if (SCSI_MAX_SG_SEGMENTS > 32)
53         SP(32),
54 #if (SCSI_MAX_SG_SEGMENTS > 64)
55         SP(64),
56 #if (SCSI_MAX_SG_SEGMENTS > 128)
57         SP(128),
58 #if (SCSI_MAX_SG_SEGMENTS > 256)
59 #error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
60 #endif
61 #endif
62 #endif
63 #endif
64         SP(SCSI_MAX_SG_SEGMENTS)
65 };
66 #undef SP
67
68 struct kmem_cache *scsi_sdb_cache;
69
70 /*
71  * When to reinvoke queueing after a resource shortage. It's 3 msecs to
72  * not change behaviour from the previous unplug mechanism, experimentation
73  * may prove this needs changing.
74  */
75 #define SCSI_QUEUE_DELAY        3
76
77 /*
78  * Function:    scsi_unprep_request()
79  *
80  * Purpose:     Remove all preparation done for a request, including its
81  *              associated scsi_cmnd, so that it can be requeued.
82  *
83  * Arguments:   req     - request to unprepare
84  *
85  * Lock status: Assumed that no locks are held upon entry.
86  *
87  * Returns:     Nothing.
88  */
89 static void scsi_unprep_request(struct request *req)
90 {
91         struct scsi_cmnd *cmd = req->special;
92
93         blk_unprep_request(req);
94         req->special = NULL;
95
96         scsi_put_command(cmd);
97 }
98
99 /**
100  * __scsi_queue_insert - private queue insertion
101  * @cmd: The SCSI command being requeued
102  * @reason:  The reason for the requeue
103  * @unbusy: Whether the queue should be unbusied
104  *
105  * This is a private queue insertion.  The public interface
106  * scsi_queue_insert() always assumes the queue should be unbusied
107  * because it's always called before the completion.  This function is
108  * for a requeue after completion, which should only occur in this
109  * file.
110  */
111 static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
112 {
113         struct Scsi_Host *host = cmd->device->host;
114         struct scsi_device *device = cmd->device;
115         struct scsi_target *starget = scsi_target(device);
116         struct request_queue *q = device->request_queue;
117         unsigned long flags;
118
119         SCSI_LOG_MLQUEUE(1,
120                  printk("Inserting command %p into mlqueue\n", cmd));
121
122         /*
123          * Set the appropriate busy bit for the device/host.
124          *
125          * If the host/device isn't busy, assume that something actually
126          * completed, and that we should be able to queue a command now.
127          *
128          * Note that the prior mid-layer assumption that any host could
129          * always queue at least one command is now broken.  The mid-layer
130          * will implement a user specifiable stall (see
131          * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
132          * if a command is requeued with no other commands outstanding
133          * either for the device or for the host.
134          */
135         switch (reason) {
136         case SCSI_MLQUEUE_HOST_BUSY:
137                 host->host_blocked = host->max_host_blocked;
138                 break;
139         case SCSI_MLQUEUE_DEVICE_BUSY:
140         case SCSI_MLQUEUE_EH_RETRY:
141                 device->device_blocked = device->max_device_blocked;
142                 break;
143         case SCSI_MLQUEUE_TARGET_BUSY:
144                 starget->target_blocked = starget->max_target_blocked;
145                 break;
146         }
147
148         /*
149          * Decrement the counters, since these commands are no longer
150          * active on the host/device.
151          */
152         if (unbusy)
153                 scsi_device_unbusy(device);
154
155         /*
156          * Requeue this command.  It will go before all other commands
157          * that are already in the queue.
158          */
159         spin_lock_irqsave(q->queue_lock, flags);
160         blk_requeue_request(q, cmd->request);
161         spin_unlock_irqrestore(q->queue_lock, flags);
162
163         kblockd_schedule_work(q, &device->requeue_work);
164
165         return 0;
166 }
167
168 /*
169  * Function:    scsi_queue_insert()
170  *
171  * Purpose:     Insert a command in the midlevel queue.
172  *
173  * Arguments:   cmd    - command that we are adding to queue.
174  *              reason - why we are inserting command to queue.
175  *
176  * Lock status: Assumed that lock is not held upon entry.
177  *
178  * Returns:     Nothing.
179  *
180  * Notes:       We do this for one of two cases.  Either the host is busy
181  *              and it cannot accept any more commands for the time being,
182  *              or the device returned QUEUE_FULL and can accept no more
183  *              commands.
184  * Notes:       This could be called either from an interrupt context or a
185  *              normal process context.
186  */
187 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
188 {
189         return __scsi_queue_insert(cmd, reason, 1);
190 }
191 /**
192  * scsi_execute - insert request and wait for the result
193  * @sdev:       scsi device
194  * @cmd:        scsi command
195  * @data_direction: data direction
196  * @buffer:     data buffer
197  * @bufflen:    len of buffer
198  * @sense:      optional sense buffer
199  * @timeout:    request timeout in seconds
200  * @retries:    number of times to retry request
201  * @flags:      or into request flags;
202  * @resid:      optional residual length
203  *
204  * returns the req->errors value which is the scsi_cmnd result
205  * field.
206  */
207 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
208                  int data_direction, void *buffer, unsigned bufflen,
209                  unsigned char *sense, int timeout, int retries, int flags,
210                  int *resid)
211 {
212         struct request *req;
213         int write = (data_direction == DMA_TO_DEVICE);
214         int ret = DRIVER_ERROR << 24;
215
216         req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
217         if (!req)
218                 return ret;
219
220         if (bufflen &&  blk_rq_map_kern(sdev->request_queue, req,
221                                         buffer, bufflen, __GFP_WAIT))
222                 goto out;
223
224         req->cmd_len = COMMAND_SIZE(cmd[0]);
225         memcpy(req->cmd, cmd, req->cmd_len);
226         req->sense = sense;
227         req->sense_len = 0;
228         req->retries = retries;
229         req->timeout = timeout;
230         req->cmd_type = REQ_TYPE_BLOCK_PC;
231         req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
232
233         /*
234          * head injection *required* here otherwise quiesce won't work
235          */
236         blk_execute_rq(req->q, NULL, req, 1);
237
238         /*
239          * Some devices (USB mass-storage in particular) may transfer
240          * garbage data together with a residue indicating that the data
241          * is invalid.  Prevent the garbage from being misinterpreted
242          * and prevent security leaks by zeroing out the excess data.
243          */
244         if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
245                 memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
246
247         if (resid)
248                 *resid = req->resid_len;
249         ret = req->errors;
250  out:
251         blk_put_request(req);
252
253         return ret;
254 }
255 EXPORT_SYMBOL(scsi_execute);
256
257
258 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
259                      int data_direction, void *buffer, unsigned bufflen,
260                      struct scsi_sense_hdr *sshdr, int timeout, int retries,
261                      int *resid)
262 {
263         char *sense = NULL;
264         int result;
265         
266         if (sshdr) {
267                 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
268                 if (!sense)
269                         return DRIVER_ERROR << 24;
270         }
271         result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
272                               sense, timeout, retries, 0, resid);
273         if (sshdr)
274                 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
275
276         kfree(sense);
277         return result;
278 }
279 EXPORT_SYMBOL(scsi_execute_req);
280
281 /*
282  * Function:    scsi_init_cmd_errh()
283  *
284  * Purpose:     Initialize cmd fields related to error handling.
285  *
286  * Arguments:   cmd     - command that is ready to be queued.
287  *
288  * Notes:       This function has the job of initializing a number of
289  *              fields related to error handling.   Typically this will
290  *              be called once for each command, as required.
291  */
292 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
293 {
294         cmd->serial_number = 0;
295         scsi_set_resid(cmd, 0);
296         memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
297         if (cmd->cmd_len == 0)
298                 cmd->cmd_len = scsi_command_size(cmd->cmnd);
299 }
300
301 void scsi_device_unbusy(struct scsi_device *sdev)
302 {
303         struct Scsi_Host *shost = sdev->host;
304         struct scsi_target *starget = scsi_target(sdev);
305         unsigned long flags;
306
307         spin_lock_irqsave(shost->host_lock, flags);
308         shost->host_busy--;
309         starget->target_busy--;
310         if (unlikely(scsi_host_in_recovery(shost) &&
311                      (shost->host_failed || shost->host_eh_scheduled)))
312                 scsi_eh_wakeup(shost);
313         spin_unlock(shost->host_lock);
314         spin_lock(sdev->request_queue->queue_lock);
315         sdev->device_busy--;
316         spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
317 }
318
319 /*
320  * Called for single_lun devices on IO completion. Clear starget_sdev_user,
321  * and call blk_run_queue for all the scsi_devices on the target -
322  * including current_sdev first.
323  *
324  * Called with *no* scsi locks held.
325  */
326 static void scsi_single_lun_run(struct scsi_device *current_sdev)
327 {
328         struct Scsi_Host *shost = current_sdev->host;
329         struct scsi_device *sdev, *tmp;
330         struct scsi_target *starget = scsi_target(current_sdev);
331         unsigned long flags;
332
333         spin_lock_irqsave(shost->host_lock, flags);
334         starget->starget_sdev_user = NULL;
335         spin_unlock_irqrestore(shost->host_lock, flags);
336
337         /*
338          * Call blk_run_queue for all LUNs on the target, starting with
339          * current_sdev. We race with others (to set starget_sdev_user),
340          * but in most cases, we will be first. Ideally, each LU on the
341          * target would get some limited time or requests on the target.
342          */
343         blk_run_queue(current_sdev->request_queue);
344
345         spin_lock_irqsave(shost->host_lock, flags);
346         if (starget->starget_sdev_user)
347                 goto out;
348         list_for_each_entry_safe(sdev, tmp, &starget->devices,
349                         same_target_siblings) {
350                 if (sdev == current_sdev)
351                         continue;
352                 if (scsi_device_get(sdev))
353                         continue;
354
355                 spin_unlock_irqrestore(shost->host_lock, flags);
356                 blk_run_queue(sdev->request_queue);
357                 spin_lock_irqsave(shost->host_lock, flags);
358         
359                 scsi_device_put(sdev);
360         }
361  out:
362         spin_unlock_irqrestore(shost->host_lock, flags);
363 }
364
365 static inline int scsi_device_is_busy(struct scsi_device *sdev)
366 {
367         if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
368                 return 1;
369
370         return 0;
371 }
372
373 static inline int scsi_target_is_busy(struct scsi_target *starget)
374 {
375         return ((starget->can_queue > 0 &&
376                  starget->target_busy >= starget->can_queue) ||
377                  starget->target_blocked);
378 }
379
380 static inline int scsi_host_is_busy(struct Scsi_Host *shost)
381 {
382         if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
383             shost->host_blocked || shost->host_self_blocked)
384                 return 1;
385
386         return 0;
387 }
388
389 /*
390  * Function:    scsi_run_queue()
391  *
392  * Purpose:     Select a proper request queue to serve next
393  *
394  * Arguments:   q       - last request's queue
395  *
396  * Returns:     Nothing
397  *
398  * Notes:       The previous command was completely finished, start
399  *              a new one if possible.
400  */
401 static void scsi_run_queue(struct request_queue *q)
402 {
403         struct scsi_device *sdev = q->queuedata;
404         struct Scsi_Host *shost;
405         LIST_HEAD(starved_list);
406         unsigned long flags;
407
408         /* if the device is dead, sdev will be NULL, so no queue to run */
409         if (!sdev)
410                 return;
411
412         shost = sdev->host;
413         if (scsi_target(sdev)->single_lun)
414                 scsi_single_lun_run(sdev);
415
416         spin_lock_irqsave(shost->host_lock, flags);
417         list_splice_init(&shost->starved_list, &starved_list);
418
419         while (!list_empty(&starved_list)) {
420                 /*
421                  * As long as shost is accepting commands and we have
422                  * starved queues, call blk_run_queue. scsi_request_fn
423                  * drops the queue_lock and can add us back to the
424                  * starved_list.
425                  *
426                  * host_lock protects the starved_list and starved_entry.
427                  * scsi_request_fn must get the host_lock before checking
428                  * or modifying starved_list or starved_entry.
429                  */
430                 if (scsi_host_is_busy(shost))
431                         break;
432
433                 sdev = list_entry(starved_list.next,
434                                   struct scsi_device, starved_entry);
435                 list_del_init(&sdev->starved_entry);
436                 if (scsi_target_is_busy(scsi_target(sdev))) {
437                         list_move_tail(&sdev->starved_entry,
438                                        &shost->starved_list);
439                         continue;
440                 }
441
442                 spin_unlock(shost->host_lock);
443                 spin_lock(sdev->request_queue->queue_lock);
444                 __blk_run_queue(sdev->request_queue);
445                 spin_unlock(sdev->request_queue->queue_lock);
446                 spin_lock(shost->host_lock);
447         }
448         /* put any unprocessed entries back */
449         list_splice(&starved_list, &shost->starved_list);
450         spin_unlock_irqrestore(shost->host_lock, flags);
451
452         blk_run_queue(q);
453 }
454
455 void scsi_requeue_run_queue(struct work_struct *work)
456 {
457         struct scsi_device *sdev;
458         struct request_queue *q;
459
460         sdev = container_of(work, struct scsi_device, requeue_work);
461         q = sdev->request_queue;
462         scsi_run_queue(q);
463 }
464
465 /*
466  * Function:    scsi_requeue_command()
467  *
468  * Purpose:     Handle post-processing of completed commands.
469  *
470  * Arguments:   q       - queue to operate on
471  *              cmd     - command that may need to be requeued.
472  *
473  * Returns:     Nothing
474  *
475  * Notes:       After command completion, there may be blocks left
476  *              over which weren't finished by the previous command
477  *              this can be for a number of reasons - the main one is
478  *              I/O errors in the middle of the request, in which case
479  *              we need to request the blocks that come after the bad
480  *              sector.
481  * Notes:       Upon return, cmd is a stale pointer.
482  */
483 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
484 {
485         struct request *req = cmd->request;
486         unsigned long flags;
487
488         spin_lock_irqsave(q->queue_lock, flags);
489         scsi_unprep_request(req);
490         blk_requeue_request(q, req);
491         spin_unlock_irqrestore(q->queue_lock, flags);
492
493         scsi_run_queue(q);
494 }
495
496 void scsi_next_command(struct scsi_cmnd *cmd)
497 {
498         struct scsi_device *sdev = cmd->device;
499         struct request_queue *q = sdev->request_queue;
500
501         /* need to hold a reference on the device before we let go of the cmd */
502         get_device(&sdev->sdev_gendev);
503
504         scsi_put_command(cmd);
505         scsi_run_queue(q);
506
507         /* ok to remove device now */
508         put_device(&sdev->sdev_gendev);
509 }
510
511 void scsi_run_host_queues(struct Scsi_Host *shost)
512 {
513         struct scsi_device *sdev;
514
515         shost_for_each_device(sdev, shost)
516                 scsi_run_queue(sdev->request_queue);
517 }
518
519 static void __scsi_release_buffers(struct scsi_cmnd *, int);
520
521 /*
522  * Function:    scsi_end_request()
523  *
524  * Purpose:     Post-processing of completed commands (usually invoked at end
525  *              of upper level post-processing and scsi_io_completion).
526  *
527  * Arguments:   cmd      - command that is complete.
528  *              error    - 0 if I/O indicates success, < 0 for I/O error.
529  *              bytes    - number of bytes of completed I/O
530  *              requeue  - indicates whether we should requeue leftovers.
531  *
532  * Lock status: Assumed that lock is not held upon entry.
533  *
534  * Returns:     cmd if requeue required, NULL otherwise.
535  *
536  * Notes:       This is called for block device requests in order to
537  *              mark some number of sectors as complete.
538  * 
539  *              We are guaranteeing that the request queue will be goosed
540  *              at some point during this call.
541  * Notes:       If cmd was requeued, upon return it will be a stale pointer.
542  */
543 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
544                                           int bytes, int requeue)
545 {
546         struct request_queue *q = cmd->device->request_queue;
547         struct request *req = cmd->request;
548
549         /*
550          * If there are blocks left over at the end, set up the command
551          * to queue the remainder of them.
552          */
553         if (blk_end_request(req, error, bytes)) {
554                 /* kill remainder if no retrys */
555                 if (error && scsi_noretry_cmd(cmd))
556                         blk_end_request_all(req, error);
557                 else {
558                         if (requeue) {
559                                 /*
560                                  * Bleah.  Leftovers again.  Stick the
561                                  * leftovers in the front of the
562                                  * queue, and goose the queue again.
563                                  */
564                                 scsi_release_buffers(cmd);
565                                 scsi_requeue_command(q, cmd);
566                                 cmd = NULL;
567                         }
568                         return cmd;
569                 }
570         }
571
572         /*
573          * This will goose the queue request function at the end, so we don't
574          * need to worry about launching another command.
575          */
576         __scsi_release_buffers(cmd, 0);
577         scsi_next_command(cmd);
578         return NULL;
579 }
580
581 static inline unsigned int scsi_sgtable_index(unsigned short nents)
582 {
583         unsigned int index;
584
585         BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
586
587         if (nents <= 8)
588                 index = 0;
589         else
590                 index = get_count_order(nents) - 3;
591
592         return index;
593 }
594
595 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
596 {
597         struct scsi_host_sg_pool *sgp;
598
599         sgp = scsi_sg_pools + scsi_sgtable_index(nents);
600         mempool_free(sgl, sgp->pool);
601 }
602
603 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
604 {
605         struct scsi_host_sg_pool *sgp;
606
607         sgp = scsi_sg_pools + scsi_sgtable_index(nents);
608         return mempool_alloc(sgp->pool, gfp_mask);
609 }
610
611 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
612                               gfp_t gfp_mask)
613 {
614         int ret;
615
616         BUG_ON(!nents);
617
618         ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
619                                gfp_mask, scsi_sg_alloc);
620         if (unlikely(ret))
621                 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
622                                 scsi_sg_free);
623
624         return ret;
625 }
626
627 static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
628 {
629         __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
630 }
631
632 static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
633 {
634
635         if (cmd->sdb.table.nents)
636                 scsi_free_sgtable(&cmd->sdb);
637
638         memset(&cmd->sdb, 0, sizeof(cmd->sdb));
639
640         if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
641                 struct scsi_data_buffer *bidi_sdb =
642                         cmd->request->next_rq->special;
643                 scsi_free_sgtable(bidi_sdb);
644                 kmem_cache_free(scsi_sdb_cache, bidi_sdb);
645                 cmd->request->next_rq->special = NULL;
646         }
647
648         if (scsi_prot_sg_count(cmd))
649                 scsi_free_sgtable(cmd->prot_sdb);
650 }
651
652 /*
653  * Function:    scsi_release_buffers()
654  *
655  * Purpose:     Completion processing for block device I/O requests.
656  *
657  * Arguments:   cmd     - command that we are bailing.
658  *
659  * Lock status: Assumed that no lock is held upon entry.
660  *
661  * Returns:     Nothing
662  *
663  * Notes:       In the event that an upper level driver rejects a
664  *              command, we must release resources allocated during
665  *              the __init_io() function.  Primarily this would involve
666  *              the scatter-gather table, and potentially any bounce
667  *              buffers.
668  */
669 void scsi_release_buffers(struct scsi_cmnd *cmd)
670 {
671         __scsi_release_buffers(cmd, 1);
672 }
673 EXPORT_SYMBOL(scsi_release_buffers);
674
675 static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
676 {
677         int error = 0;
678
679         switch(host_byte(result)) {
680         case DID_TRANSPORT_FAILFAST:
681                 error = -ENOLINK;
682                 break;
683         case DID_TARGET_FAILURE:
684                 cmd->result |= (DID_OK << 16);
685                 error = -EREMOTEIO;
686                 break;
687         case DID_NEXUS_FAILURE:
688                 cmd->result |= (DID_OK << 16);
689                 error = -EBADE;
690                 break;
691         default:
692                 error = -EIO;
693                 break;
694         }
695
696         return error;
697 }
698
699 /*
700  * Function:    scsi_io_completion()
701  *
702  * Purpose:     Completion processing for block device I/O requests.
703  *
704  * Arguments:   cmd   - command that is finished.
705  *
706  * Lock status: Assumed that no lock is held upon entry.
707  *
708  * Returns:     Nothing
709  *
710  * Notes:       This function is matched in terms of capabilities to
711  *              the function that created the scatter-gather list.
712  *              In other words, if there are no bounce buffers
713  *              (the normal case for most drivers), we don't need
714  *              the logic to deal with cleaning up afterwards.
715  *
716  *              We must call scsi_end_request().  This will finish off
717  *              the specified number of sectors.  If we are done, the
718  *              command block will be released and the queue function
719  *              will be goosed.  If we are not done then we have to
720  *              figure out what to do next:
721  *
722  *              a) We can call scsi_requeue_command().  The request
723  *                 will be unprepared and put back on the queue.  Then
724  *                 a new command will be created for it.  This should
725  *                 be used if we made forward progress, or if we want
726  *                 to switch from READ(10) to READ(6) for example.
727  *
728  *              b) We can call scsi_queue_insert().  The request will
729  *                 be put back on the queue and retried using the same
730  *                 command as before, possibly after a delay.
731  *
732  *              c) We can call blk_end_request() with -EIO to fail
733  *                 the remainder of the request.
734  */
735 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
736 {
737         int result = cmd->result;
738         struct request_queue *q = cmd->device->request_queue;
739         struct request *req = cmd->request;
740         int error = 0;
741         struct scsi_sense_hdr sshdr;
742         int sense_valid = 0;
743         int sense_deferred = 0;
744         enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
745               ACTION_DELAYED_RETRY} action;
746         char *description = NULL;
747
748         if (result) {
749                 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
750                 if (sense_valid)
751                         sense_deferred = scsi_sense_is_deferred(&sshdr);
752         }
753
754         if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
755                 req->errors = result;
756                 if (result) {
757                         if (sense_valid && req->sense) {
758                                 /*
759                                  * SG_IO wants current and deferred errors
760                                  */
761                                 int len = 8 + cmd->sense_buffer[7];
762
763                                 if (len > SCSI_SENSE_BUFFERSIZE)
764                                         len = SCSI_SENSE_BUFFERSIZE;
765                                 memcpy(req->sense, cmd->sense_buffer,  len);
766                                 req->sense_len = len;
767                         }
768                         if (!sense_deferred)
769                                 error = __scsi_error_from_host_byte(cmd, result);
770                 }
771
772                 req->resid_len = scsi_get_resid(cmd);
773
774                 if (scsi_bidi_cmnd(cmd)) {
775                         /*
776                          * Bidi commands Must be complete as a whole,
777                          * both sides at once.
778                          */
779                         req->next_rq->resid_len = scsi_in(cmd)->resid;
780
781                         scsi_release_buffers(cmd);
782                         blk_end_request_all(req, 0);
783
784                         scsi_next_command(cmd);
785                         return;
786                 }
787         }
788
789         /* no bidi support for !REQ_TYPE_BLOCK_PC yet */
790         BUG_ON(blk_bidi_rq(req));
791
792         /*
793          * Next deal with any sectors which we were able to correctly
794          * handle.
795          */
796         SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, "
797                                       "%d bytes done.\n",
798                                       blk_rq_sectors(req), good_bytes));
799
800         /*
801          * Recovered errors need reporting, but they're always treated
802          * as success, so fiddle the result code here.  For BLOCK_PC
803          * we already took a copy of the original into rq->errors which
804          * is what gets returned to the user
805          */
806         if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
807                 /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
808                  * print since caller wants ATA registers. Only occurs on
809                  * SCSI ATA PASS_THROUGH commands when CK_COND=1
810                  */
811                 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
812                         ;
813                 else if (!(req->cmd_flags & REQ_QUIET))
814                         scsi_print_sense("", cmd);
815                 result = 0;
816                 /* BLOCK_PC may have set error */
817                 error = 0;
818         }
819
820         /*
821          * A number of bytes were successfully read.  If there
822          * are leftovers and there is some kind of error
823          * (result != 0), retry the rest.
824          */
825         if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
826                 return;
827
828         error = __scsi_error_from_host_byte(cmd, result);
829
830         if (host_byte(result) == DID_RESET) {
831                 /* Third party bus reset or reset for error recovery
832                  * reasons.  Just retry the command and see what
833                  * happens.
834                  */
835                 action = ACTION_RETRY;
836         } else if (sense_valid && !sense_deferred) {
837                 switch (sshdr.sense_key) {
838                 case UNIT_ATTENTION:
839                         if (cmd->device->removable) {
840                                 /* Detected disc change.  Set a bit
841                                  * and quietly refuse further access.
842                                  */
843                                 cmd->device->changed = 1;
844                                 description = "Media Changed";
845                                 action = ACTION_FAIL;
846                         } else {
847                                 /* Must have been a power glitch, or a
848                                  * bus reset.  Could not have been a
849                                  * media change, so we just retry the
850                                  * command and see what happens.
851                                  */
852                                 action = ACTION_RETRY;
853                         }
854                         break;
855                 case ILLEGAL_REQUEST:
856                         /* If we had an ILLEGAL REQUEST returned, then
857                          * we may have performed an unsupported
858                          * command.  The only thing this should be
859                          * would be a ten byte read where only a six
860                          * byte read was supported.  Also, on a system
861                          * where READ CAPACITY failed, we may have
862                          * read past the end of the disk.
863                          */
864                         if ((cmd->device->use_10_for_rw &&
865                             sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
866                             (cmd->cmnd[0] == READ_10 ||
867                              cmd->cmnd[0] == WRITE_10)) {
868                                 /* This will issue a new 6-byte command. */
869                                 cmd->device->use_10_for_rw = 0;
870                                 action = ACTION_REPREP;
871                         } else if (sshdr.asc == 0x10) /* DIX */ {
872                                 description = "Host Data Integrity Failure";
873                                 action = ACTION_FAIL;
874                                 error = -EILSEQ;
875                         /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
876                         } else if ((sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
877                                    (cmd->cmnd[0] == UNMAP ||
878                                     cmd->cmnd[0] == WRITE_SAME_16 ||
879                                     cmd->cmnd[0] == WRITE_SAME)) {
880                                 description = "Discard failure";
881                                 action = ACTION_FAIL;
882                         } else
883                                 action = ACTION_FAIL;
884                         break;
885                 case ABORTED_COMMAND:
886                         action = ACTION_FAIL;
887                         if (sshdr.asc == 0x10) { /* DIF */
888                                 description = "Target Data Integrity Failure";
889                                 error = -EILSEQ;
890                         }
891                         break;
892                 case NOT_READY:
893                         /* If the device is in the process of becoming
894                          * ready, or has a temporary blockage, retry.
895                          */
896                         if (sshdr.asc == 0x04) {
897                                 switch (sshdr.ascq) {
898                                 case 0x01: /* becoming ready */
899                                 case 0x04: /* format in progress */
900                                 case 0x05: /* rebuild in progress */
901                                 case 0x06: /* recalculation in progress */
902                                 case 0x07: /* operation in progress */
903                                 case 0x08: /* Long write in progress */
904                                 case 0x09: /* self test in progress */
905                                 case 0x14: /* space allocation in progress */
906                                         action = ACTION_DELAYED_RETRY;
907                                         break;
908                                 default:
909                                         description = "Device not ready";
910                                         action = ACTION_FAIL;
911                                         break;
912                                 }
913                         } else {
914                                 description = "Device not ready";
915                                 action = ACTION_FAIL;
916                         }
917                         break;
918                 case VOLUME_OVERFLOW:
919                         /* See SSC3rXX or current. */
920                         action = ACTION_FAIL;
921                         break;
922                 default:
923                         description = "Unhandled sense code";
924                         action = ACTION_FAIL;
925                         break;
926                 }
927         } else {
928                 description = "Unhandled error code";
929                 action = ACTION_FAIL;
930         }
931
932         switch (action) {
933         case ACTION_FAIL:
934                 /* Give up and fail the remainder of the request */
935                 scsi_release_buffers(cmd);
936                 if (!(req->cmd_flags & REQ_QUIET)) {
937                         if (description)
938                                 scmd_printk(KERN_INFO, cmd, "%s\n",
939                                             description);
940                         scsi_print_result(cmd);
941                         if (driver_byte(result) & DRIVER_SENSE)
942                                 scsi_print_sense("", cmd);
943                         scsi_print_command(cmd);
944                 }
945                 if (blk_end_request_err(req, error))
946                         scsi_requeue_command(q, cmd);
947                 else
948                         scsi_next_command(cmd);
949                 break;
950         case ACTION_REPREP:
951                 /* Unprep the request and put it back at the head of the queue.
952                  * A new command will be prepared and issued.
953                  */
954                 scsi_release_buffers(cmd);
955                 scsi_requeue_command(q, cmd);
956                 break;
957         case ACTION_RETRY:
958                 /* Retry the same command immediately */
959                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
960                 break;
961         case ACTION_DELAYED_RETRY:
962                 /* Retry the same command after a delay */
963                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
964                 break;
965         }
966 }
967
968 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
969                              gfp_t gfp_mask)
970 {
971         int count;
972
973         /*
974          * If sg table allocation fails, requeue request later.
975          */
976         if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
977                                         gfp_mask))) {
978                 return BLKPREP_DEFER;
979         }
980
981         req->buffer = NULL;
982
983         /* 
984          * Next, walk the list, and fill in the addresses and sizes of
985          * each segment.
986          */
987         count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
988         BUG_ON(count > sdb->table.nents);
989         sdb->table.nents = count;
990         sdb->length = blk_rq_bytes(req);
991         return BLKPREP_OK;
992 }
993
994 /*
995  * Function:    scsi_init_io()
996  *
997  * Purpose:     SCSI I/O initialize function.
998  *
999  * Arguments:   cmd   - Command descriptor we wish to initialize
1000  *
1001  * Returns:     0 on success
1002  *              BLKPREP_DEFER if the failure is retryable
1003  *              BLKPREP_KILL if the failure is fatal
1004  */
1005 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1006 {
1007         struct request *rq = cmd->request;
1008
1009         int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask);
1010         if (error)
1011                 goto err_exit;
1012
1013         if (blk_bidi_rq(rq)) {
1014                 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1015                         scsi_sdb_cache, GFP_ATOMIC);
1016                 if (!bidi_sdb) {
1017                         error = BLKPREP_DEFER;
1018                         goto err_exit;
1019                 }
1020
1021                 rq->next_rq->special = bidi_sdb;
1022                 error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC);
1023                 if (error)
1024                         goto err_exit;
1025         }
1026
1027         if (blk_integrity_rq(rq)) {
1028                 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1029                 int ivecs, count;
1030
1031                 BUG_ON(prot_sdb == NULL);
1032                 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1033
1034                 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1035                         error = BLKPREP_DEFER;
1036                         goto err_exit;
1037                 }
1038
1039                 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1040                                                 prot_sdb->table.sgl);
1041                 BUG_ON(unlikely(count > ivecs));
1042                 BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1043
1044                 cmd->prot_sdb = prot_sdb;
1045                 cmd->prot_sdb->table.nents = count;
1046         }
1047
1048         return BLKPREP_OK ;
1049
1050 err_exit:
1051         scsi_release_buffers(cmd);
1052         cmd->request->special = NULL;
1053         scsi_put_command(cmd);
1054         return error;
1055 }
1056 EXPORT_SYMBOL(scsi_init_io);
1057
1058 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1059                 struct request *req)
1060 {
1061         struct scsi_cmnd *cmd;
1062
1063         if (!req->special) {
1064                 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1065                 if (unlikely(!cmd))
1066                         return NULL;
1067                 req->special = cmd;
1068         } else {
1069                 cmd = req->special;
1070         }
1071
1072         /* pull a tag out of the request if we have one */
1073         cmd->tag = req->tag;
1074         cmd->request = req;
1075
1076         cmd->cmnd = req->cmd;
1077         cmd->prot_op = SCSI_PROT_NORMAL;
1078
1079         return cmd;
1080 }
1081
1082 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1083 {
1084         struct scsi_cmnd *cmd;
1085         int ret = scsi_prep_state_check(sdev, req);
1086
1087         if (ret != BLKPREP_OK)
1088                 return ret;
1089
1090         cmd = scsi_get_cmd_from_req(sdev, req);
1091         if (unlikely(!cmd))
1092                 return BLKPREP_DEFER;
1093
1094         /*
1095          * BLOCK_PC requests may transfer data, in which case they must
1096          * a bio attached to them.  Or they might contain a SCSI command
1097          * that does not transfer data, in which case they may optionally
1098          * submit a request without an attached bio.
1099          */
1100         if (req->bio) {
1101                 int ret;
1102
1103                 BUG_ON(!req->nr_phys_segments);
1104
1105                 ret = scsi_init_io(cmd, GFP_ATOMIC);
1106                 if (unlikely(ret))
1107                         return ret;
1108         } else {
1109                 BUG_ON(blk_rq_bytes(req));
1110
1111                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1112                 req->buffer = NULL;
1113         }
1114
1115         cmd->cmd_len = req->cmd_len;
1116         if (!blk_rq_bytes(req))
1117                 cmd->sc_data_direction = DMA_NONE;
1118         else if (rq_data_dir(req) == WRITE)
1119                 cmd->sc_data_direction = DMA_TO_DEVICE;
1120         else
1121                 cmd->sc_data_direction = DMA_FROM_DEVICE;
1122         
1123         cmd->transfersize = blk_rq_bytes(req);
1124         cmd->allowed = req->retries;
1125         return BLKPREP_OK;
1126 }
1127 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1128
1129 /*
1130  * Setup a REQ_TYPE_FS command.  These are simple read/write request
1131  * from filesystems that still need to be translated to SCSI CDBs from
1132  * the ULD.
1133  */
1134 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1135 {
1136         struct scsi_cmnd *cmd;
1137         int ret = scsi_prep_state_check(sdev, req);
1138
1139         if (ret != BLKPREP_OK)
1140                 return ret;
1141
1142         if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1143                          && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1144                 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1145                 if (ret != BLKPREP_OK)
1146                         return ret;
1147         }
1148
1149         /*
1150          * Filesystem requests must transfer data.
1151          */
1152         BUG_ON(!req->nr_phys_segments);
1153
1154         cmd = scsi_get_cmd_from_req(sdev, req);
1155         if (unlikely(!cmd))
1156                 return BLKPREP_DEFER;
1157
1158         memset(cmd->cmnd, 0, BLK_MAX_CDB);
1159         return scsi_init_io(cmd, GFP_ATOMIC);
1160 }
1161 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1162
1163 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1164 {
1165         int ret = BLKPREP_OK;
1166
1167         /*
1168          * If the device is not in running state we will reject some
1169          * or all commands.
1170          */
1171         if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1172                 switch (sdev->sdev_state) {
1173                 case SDEV_OFFLINE:
1174                         /*
1175                          * If the device is offline we refuse to process any
1176                          * commands.  The device must be brought online
1177                          * before trying any recovery commands.
1178                          */
1179                         sdev_printk(KERN_ERR, sdev,
1180                                     "rejecting I/O to offline device\n");
1181                         ret = BLKPREP_KILL;
1182                         break;
1183                 case SDEV_DEL:
1184                         /*
1185                          * If the device is fully deleted, we refuse to
1186                          * process any commands as well.
1187                          */
1188                         sdev_printk(KERN_ERR, sdev,
1189                                     "rejecting I/O to dead device\n");
1190                         ret = BLKPREP_KILL;
1191                         break;
1192                 case SDEV_QUIESCE:
1193                 case SDEV_BLOCK:
1194                 case SDEV_CREATED_BLOCK:
1195                         /*
1196                          * If the devices is blocked we defer normal commands.
1197                          */
1198                         if (!(req->cmd_flags & REQ_PREEMPT))
1199                                 ret = BLKPREP_DEFER;
1200                         break;
1201                 default:
1202                         /*
1203                          * For any other not fully online state we only allow
1204                          * special commands.  In particular any user initiated
1205                          * command is not allowed.
1206                          */
1207                         if (!(req->cmd_flags & REQ_PREEMPT))
1208                                 ret = BLKPREP_KILL;
1209                         break;
1210                 }
1211         }
1212         return ret;
1213 }
1214 EXPORT_SYMBOL(scsi_prep_state_check);
1215
1216 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1217 {
1218         struct scsi_device *sdev = q->queuedata;
1219
1220         switch (ret) {
1221         case BLKPREP_KILL:
1222                 req->errors = DID_NO_CONNECT << 16;
1223                 /* release the command and kill it */
1224                 if (req->special) {
1225                         struct scsi_cmnd *cmd = req->special;
1226                         scsi_release_buffers(cmd);
1227                         scsi_put_command(cmd);
1228                         req->special = NULL;
1229                 }
1230                 break;
1231         case BLKPREP_DEFER:
1232                 /*
1233                  * If we defer, the blk_peek_request() returns NULL, but the
1234                  * queue must be restarted, so we schedule a callback to happen
1235                  * shortly.
1236                  */
1237                 if (sdev->device_busy == 0)
1238                         blk_delay_queue(q, SCSI_QUEUE_DELAY);
1239                 break;
1240         default:
1241                 req->cmd_flags |= REQ_DONTPREP;
1242         }
1243
1244         return ret;
1245 }
1246 EXPORT_SYMBOL(scsi_prep_return);
1247
1248 int scsi_prep_fn(struct request_queue *q, struct request *req)
1249 {
1250         struct scsi_device *sdev = q->queuedata;
1251         int ret = BLKPREP_KILL;
1252
1253         if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1254                 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1255         return scsi_prep_return(q, req, ret);
1256 }
1257 EXPORT_SYMBOL(scsi_prep_fn);
1258
1259 /*
1260  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1261  * return 0.
1262  *
1263  * Called with the queue_lock held.
1264  */
1265 static inline int scsi_dev_queue_ready(struct request_queue *q,
1266                                   struct scsi_device *sdev)
1267 {
1268         if (sdev->device_busy == 0 && sdev->device_blocked) {
1269                 /*
1270                  * unblock after device_blocked iterates to zero
1271                  */
1272                 if (--sdev->device_blocked == 0) {
1273                         SCSI_LOG_MLQUEUE(3,
1274                                    sdev_printk(KERN_INFO, sdev,
1275                                    "unblocking device at zero depth\n"));
1276                 } else {
1277                         blk_delay_queue(q, SCSI_QUEUE_DELAY);
1278                         return 0;
1279                 }
1280         }
1281         if (scsi_device_is_busy(sdev))
1282                 return 0;
1283
1284         return 1;
1285 }
1286
1287
1288 /*
1289  * scsi_target_queue_ready: checks if there we can send commands to target
1290  * @sdev: scsi device on starget to check.
1291  *
1292  * Called with the host lock held.
1293  */
1294 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1295                                            struct scsi_device *sdev)
1296 {
1297         struct scsi_target *starget = scsi_target(sdev);
1298
1299         if (starget->single_lun) {
1300                 if (starget->starget_sdev_user &&
1301                     starget->starget_sdev_user != sdev)
1302                         return 0;
1303                 starget->starget_sdev_user = sdev;
1304         }
1305
1306         if (starget->target_busy == 0 && starget->target_blocked) {
1307                 /*
1308                  * unblock after target_blocked iterates to zero
1309                  */
1310                 if (--starget->target_blocked == 0) {
1311                         SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1312                                          "unblocking target at zero depth\n"));
1313                 } else
1314                         return 0;
1315         }
1316
1317         if (scsi_target_is_busy(starget)) {
1318                 if (list_empty(&sdev->starved_entry))
1319                         list_add_tail(&sdev->starved_entry,
1320                                       &shost->starved_list);
1321                 return 0;
1322         }
1323
1324         /* We're OK to process the command, so we can't be starved */
1325         if (!list_empty(&sdev->starved_entry))
1326                 list_del_init(&sdev->starved_entry);
1327         return 1;
1328 }
1329
1330 /*
1331  * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1332  * return 0. We must end up running the queue again whenever 0 is
1333  * returned, else IO can hang.
1334  *
1335  * Called with host_lock held.
1336  */
1337 static inline int scsi_host_queue_ready(struct request_queue *q,
1338                                    struct Scsi_Host *shost,
1339                                    struct scsi_device *sdev)
1340 {
1341         if (scsi_host_in_recovery(shost))
1342                 return 0;
1343         if (shost->host_busy == 0 && shost->host_blocked) {
1344                 /*
1345                  * unblock after host_blocked iterates to zero
1346                  */
1347                 if (--shost->host_blocked == 0) {
1348                         SCSI_LOG_MLQUEUE(3,
1349                                 printk("scsi%d unblocking host at zero depth\n",
1350                                         shost->host_no));
1351                 } else {
1352                         return 0;
1353                 }
1354         }
1355         if (scsi_host_is_busy(shost)) {
1356                 if (list_empty(&sdev->starved_entry))
1357                         list_add_tail(&sdev->starved_entry, &shost->starved_list);
1358                 return 0;
1359         }
1360
1361         /* We're OK to process the command, so we can't be starved */
1362         if (!list_empty(&sdev->starved_entry))
1363                 list_del_init(&sdev->starved_entry);
1364
1365         return 1;
1366 }
1367
1368 /*
1369  * Busy state exporting function for request stacking drivers.
1370  *
1371  * For efficiency, no lock is taken to check the busy state of
1372  * shost/starget/sdev, since the returned value is not guaranteed and
1373  * may be changed after request stacking drivers call the function,
1374  * regardless of taking lock or not.
1375  *
1376  * When scsi can't dispatch I/Os anymore and needs to kill I/Os
1377  * (e.g. !sdev), scsi needs to return 'not busy'.
1378  * Otherwise, request stacking drivers may hold requests forever.
1379  */
1380 static int scsi_lld_busy(struct request_queue *q)
1381 {
1382         struct scsi_device *sdev = q->queuedata;
1383         struct Scsi_Host *shost;
1384         struct scsi_target *starget;
1385
1386         if (!sdev)
1387                 return 0;
1388
1389         shost = sdev->host;
1390         starget = scsi_target(sdev);
1391
1392         if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
1393             scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
1394                 return 1;
1395
1396         return 0;
1397 }
1398
1399 /*
1400  * Kill a request for a dead device
1401  */
1402 static void scsi_kill_request(struct request *req, struct request_queue *q)
1403 {
1404         struct scsi_cmnd *cmd = req->special;
1405         struct scsi_device *sdev;
1406         struct scsi_target *starget;
1407         struct Scsi_Host *shost;
1408
1409         blk_start_request(req);
1410
1411         scmd_printk(KERN_INFO, cmd, "killing request\n");
1412
1413         sdev = cmd->device;
1414         starget = scsi_target(sdev);
1415         shost = sdev->host;
1416         scsi_init_cmd_errh(cmd);
1417         cmd->result = DID_NO_CONNECT << 16;
1418         atomic_inc(&cmd->device->iorequest_cnt);
1419
1420         /*
1421          * SCSI request completion path will do scsi_device_unbusy(),
1422          * bump busy counts.  To bump the counters, we need to dance
1423          * with the locks as normal issue path does.
1424          */
1425         sdev->device_busy++;
1426         spin_unlock(sdev->request_queue->queue_lock);
1427         spin_lock(shost->host_lock);
1428         shost->host_busy++;
1429         starget->target_busy++;
1430         spin_unlock(shost->host_lock);
1431         spin_lock(sdev->request_queue->queue_lock);
1432
1433         blk_complete_request(req);
1434 }
1435
1436 static void scsi_softirq_done(struct request *rq)
1437 {
1438         struct scsi_cmnd *cmd = rq->special;
1439         unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1440         int disposition;
1441
1442         INIT_LIST_HEAD(&cmd->eh_entry);
1443
1444         atomic_inc(&cmd->device->iodone_cnt);
1445         if (cmd->result)
1446                 atomic_inc(&cmd->device->ioerr_cnt);
1447
1448         disposition = scsi_decide_disposition(cmd);
1449         if (disposition != SUCCESS &&
1450             time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1451                 sdev_printk(KERN_ERR, cmd->device,
1452                             "timing out command, waited %lus\n",
1453                             wait_for/HZ);
1454                 disposition = SUCCESS;
1455         }
1456                         
1457         scsi_log_completion(cmd, disposition);
1458
1459         switch (disposition) {
1460                 case SUCCESS:
1461                         scsi_finish_command(cmd);
1462                         break;
1463                 case NEEDS_RETRY:
1464                         scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1465                         break;
1466                 case ADD_TO_MLQUEUE:
1467                         scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1468                         break;
1469                 default:
1470                         if (!scsi_eh_scmd_add(cmd, 0))
1471                                 scsi_finish_command(cmd);
1472         }
1473 }
1474
1475 /*
1476  * Function:    scsi_request_fn()
1477  *
1478  * Purpose:     Main strategy routine for SCSI.
1479  *
1480  * Arguments:   q       - Pointer to actual queue.
1481  *
1482  * Returns:     Nothing
1483  *
1484  * Lock status: IO request lock assumed to be held when called.
1485  */
1486 static void scsi_request_fn(struct request_queue *q)
1487 {
1488         struct scsi_device *sdev = q->queuedata;
1489         struct Scsi_Host *shost;
1490         struct scsi_cmnd *cmd;
1491         struct request *req;
1492
1493         if (!sdev) {
1494                 while ((req = blk_peek_request(q)) != NULL)
1495                         scsi_kill_request(req, q);
1496                 return;
1497         }
1498
1499         if(!get_device(&sdev->sdev_gendev))
1500                 /* We must be tearing the block queue down already */
1501                 return;
1502
1503         /*
1504          * To start with, we keep looping until the queue is empty, or until
1505          * the host is no longer able to accept any more requests.
1506          */
1507         shost = sdev->host;
1508         for (;;) {
1509                 int rtn;
1510                 /*
1511                  * get next queueable request.  We do this early to make sure
1512                  * that the request is fully prepared even if we cannot 
1513                  * accept it.
1514                  */
1515                 req = blk_peek_request(q);
1516                 if (!req || !scsi_dev_queue_ready(q, sdev))
1517                         break;
1518
1519                 if (unlikely(!scsi_device_online(sdev))) {
1520                         sdev_printk(KERN_ERR, sdev,
1521                                     "rejecting I/O to offline device\n");
1522                         scsi_kill_request(req, q);
1523                         continue;
1524                 }
1525
1526
1527                 /*
1528                  * Remove the request from the request list.
1529                  */
1530                 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1531                         blk_start_request(req);
1532                 sdev->device_busy++;
1533
1534                 spin_unlock(q->queue_lock);
1535                 cmd = req->special;
1536                 if (unlikely(cmd == NULL)) {
1537                         printk(KERN_CRIT "impossible request in %s.\n"
1538                                          "please mail a stack trace to "
1539                                          "linux-scsi@vger.kernel.org\n",
1540                                          __func__);
1541                         blk_dump_rq_flags(req, "foo");
1542                         BUG();
1543                 }
1544                 spin_lock(shost->host_lock);
1545
1546                 /*
1547                  * We hit this when the driver is using a host wide
1548                  * tag map. For device level tag maps the queue_depth check
1549                  * in the device ready fn would prevent us from trying
1550                  * to allocate a tag. Since the map is a shared host resource
1551                  * we add the dev to the starved list so it eventually gets
1552                  * a run when a tag is freed.
1553                  */
1554                 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1555                         if (list_empty(&sdev->starved_entry))
1556                                 list_add_tail(&sdev->starved_entry,
1557                                               &shost->starved_list);
1558                         goto not_ready;
1559                 }
1560
1561                 if (!scsi_target_queue_ready(shost, sdev))
1562                         goto not_ready;
1563
1564                 if (!scsi_host_queue_ready(q, shost, sdev))
1565                         goto not_ready;
1566
1567                 scsi_target(sdev)->target_busy++;
1568                 shost->host_busy++;
1569
1570                 /*
1571                  * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1572                  *              take the lock again.
1573                  */
1574                 spin_unlock_irq(shost->host_lock);
1575
1576                 /*
1577                  * Finally, initialize any error handling parameters, and set up
1578                  * the timers for timeouts.
1579                  */
1580                 scsi_init_cmd_errh(cmd);
1581
1582                 /*
1583                  * Dispatch the command to the low-level driver.
1584                  */
1585                 rtn = scsi_dispatch_cmd(cmd);
1586                 spin_lock_irq(q->queue_lock);
1587                 if (rtn)
1588                         goto out_delay;
1589         }
1590
1591         goto out;
1592
1593  not_ready:
1594         spin_unlock_irq(shost->host_lock);
1595
1596         /*
1597          * lock q, handle tag, requeue req, and decrement device_busy. We
1598          * must return with queue_lock held.
1599          *
1600          * Decrementing device_busy without checking it is OK, as all such
1601          * cases (host limits or settings) should run the queue at some
1602          * later time.
1603          */
1604         spin_lock_irq(q->queue_lock);
1605         blk_requeue_request(q, req);
1606         sdev->device_busy--;
1607 out_delay:
1608         if (sdev->device_busy == 0)
1609                 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1610 out:
1611         /* must be careful here...if we trigger the ->remove() function
1612          * we cannot be holding the q lock */
1613         spin_unlock_irq(q->queue_lock);
1614         put_device(&sdev->sdev_gendev);
1615         spin_lock_irq(q->queue_lock);
1616 }
1617
1618 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1619 {
1620         struct device *host_dev;
1621         u64 bounce_limit = 0xffffffff;
1622
1623         if (shost->unchecked_isa_dma)
1624                 return BLK_BOUNCE_ISA;
1625         /*
1626          * Platforms with virtual-DMA translation
1627          * hardware have no practical limit.
1628          */
1629         if (!PCI_DMA_BUS_IS_PHYS)
1630                 return BLK_BOUNCE_ANY;
1631
1632         host_dev = scsi_get_device(shost);
1633         if (host_dev && host_dev->dma_mask)
1634                 bounce_limit = *host_dev->dma_mask;
1635
1636         return bounce_limit;
1637 }
1638 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1639
1640 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1641                                          request_fn_proc *request_fn)
1642 {
1643         struct request_queue *q;
1644         struct device *dev = shost->shost_gendev.parent;
1645
1646         q = blk_init_queue(request_fn, NULL);
1647         if (!q)
1648                 return NULL;
1649
1650         /*
1651          * this limit is imposed by hardware restrictions
1652          */
1653         blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1654                                         SCSI_MAX_SG_CHAIN_SEGMENTS));
1655
1656         if (scsi_host_prot_dma(shost)) {
1657                 shost->sg_prot_tablesize =
1658                         min_not_zero(shost->sg_prot_tablesize,
1659                                      (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1660                 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1661                 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1662         }
1663
1664         blk_queue_max_hw_sectors(q, shost->max_sectors);
1665         blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1666         blk_queue_segment_boundary(q, shost->dma_boundary);
1667         dma_set_seg_boundary(dev, shost->dma_boundary);
1668
1669         blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1670
1671         if (!shost->use_clustering)
1672                 q->limits.cluster = 0;
1673
1674         /*
1675          * set a reasonable default alignment on word boundaries: the
1676          * host and device may alter it using
1677          * blk_queue_update_dma_alignment() later.
1678          */
1679         blk_queue_dma_alignment(q, 0x03);
1680
1681         return q;
1682 }
1683 EXPORT_SYMBOL(__scsi_alloc_queue);
1684
1685 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1686 {
1687         struct request_queue *q;
1688
1689         q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1690         if (!q)
1691                 return NULL;
1692
1693         blk_queue_prep_rq(q, scsi_prep_fn);
1694         blk_queue_softirq_done(q, scsi_softirq_done);
1695         blk_queue_rq_timed_out(q, scsi_times_out);
1696         blk_queue_lld_busy(q, scsi_lld_busy);
1697         return q;
1698 }
1699
1700 void scsi_free_queue(struct request_queue *q)
1701 {
1702         unsigned long flags;
1703
1704         WARN_ON(q->queuedata);
1705
1706         /* cause scsi_request_fn() to kill all non-finished requests */
1707         spin_lock_irqsave(q->queue_lock, flags);
1708         q->request_fn(q);
1709         spin_unlock_irqrestore(q->queue_lock, flags);
1710
1711         blk_cleanup_queue(q);
1712 }
1713
1714 /*
1715  * Function:    scsi_block_requests()
1716  *
1717  * Purpose:     Utility function used by low-level drivers to prevent further
1718  *              commands from being queued to the device.
1719  *
1720  * Arguments:   shost       - Host in question
1721  *
1722  * Returns:     Nothing
1723  *
1724  * Lock status: No locks are assumed held.
1725  *
1726  * Notes:       There is no timer nor any other means by which the requests
1727  *              get unblocked other than the low-level driver calling
1728  *              scsi_unblock_requests().
1729  */
1730 void scsi_block_requests(struct Scsi_Host *shost)
1731 {
1732         shost->host_self_blocked = 1;
1733 }
1734 EXPORT_SYMBOL(scsi_block_requests);
1735
1736 /*
1737  * Function:    scsi_unblock_requests()
1738  *
1739  * Purpose:     Utility function used by low-level drivers to allow further
1740  *              commands from being queued to the device.
1741  *
1742  * Arguments:   shost       - Host in question
1743  *
1744  * Returns:     Nothing
1745  *
1746  * Lock status: No locks are assumed held.
1747  *
1748  * Notes:       There is no timer nor any other means by which the requests
1749  *              get unblocked other than the low-level driver calling
1750  *              scsi_unblock_requests().
1751  *
1752  *              This is done as an API function so that changes to the
1753  *              internals of the scsi mid-layer won't require wholesale
1754  *              changes to drivers that use this feature.
1755  */
1756 void scsi_unblock_requests(struct Scsi_Host *shost)
1757 {
1758         shost->host_self_blocked = 0;
1759         scsi_run_host_queues(shost);
1760 }
1761 EXPORT_SYMBOL(scsi_unblock_requests);
1762
1763 int __init scsi_init_queue(void)
1764 {
1765         int i;
1766
1767         scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1768                                            sizeof(struct scsi_data_buffer),
1769                                            0, 0, NULL);
1770         if (!scsi_sdb_cache) {
1771                 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1772                 return -ENOMEM;
1773         }
1774
1775         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1776                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1777                 int size = sgp->size * sizeof(struct scatterlist);
1778
1779                 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1780                                 SLAB_HWCACHE_ALIGN, NULL);
1781                 if (!sgp->slab) {
1782                         printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1783                                         sgp->name);
1784                         goto cleanup_sdb;
1785                 }
1786
1787                 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1788                                                      sgp->slab);
1789                 if (!sgp->pool) {
1790                         printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1791                                         sgp->name);
1792                         goto cleanup_sdb;
1793                 }
1794         }
1795
1796         return 0;
1797
1798 cleanup_sdb:
1799         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1800                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1801                 if (sgp->pool)
1802                         mempool_destroy(sgp->pool);
1803                 if (sgp->slab)
1804                         kmem_cache_destroy(sgp->slab);
1805         }
1806         kmem_cache_destroy(scsi_sdb_cache);
1807
1808         return -ENOMEM;
1809 }
1810
1811 void scsi_exit_queue(void)
1812 {
1813         int i;
1814
1815         kmem_cache_destroy(scsi_sdb_cache);
1816
1817         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1818                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1819                 mempool_destroy(sgp->pool);
1820                 kmem_cache_destroy(sgp->slab);
1821         }
1822 }
1823
1824 /**
1825  *      scsi_mode_select - issue a mode select
1826  *      @sdev:  SCSI device to be queried
1827  *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
1828  *      @sp:    Save page bit (0 == don't save, 1 == save)
1829  *      @modepage: mode page being requested
1830  *      @buffer: request buffer (may not be smaller than eight bytes)
1831  *      @len:   length of request buffer.
1832  *      @timeout: command timeout
1833  *      @retries: number of retries before failing
1834  *      @data: returns a structure abstracting the mode header data
1835  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
1836  *              must be SCSI_SENSE_BUFFERSIZE big.
1837  *
1838  *      Returns zero if successful; negative error number or scsi
1839  *      status on error
1840  *
1841  */
1842 int
1843 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1844                  unsigned char *buffer, int len, int timeout, int retries,
1845                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1846 {
1847         unsigned char cmd[10];
1848         unsigned char *real_buffer;
1849         int ret;
1850
1851         memset(cmd, 0, sizeof(cmd));
1852         cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1853
1854         if (sdev->use_10_for_ms) {
1855                 if (len > 65535)
1856                         return -EINVAL;
1857                 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1858                 if (!real_buffer)
1859                         return -ENOMEM;
1860                 memcpy(real_buffer + 8, buffer, len);
1861                 len += 8;
1862                 real_buffer[0] = 0;
1863                 real_buffer[1] = 0;
1864                 real_buffer[2] = data->medium_type;
1865                 real_buffer[3] = data->device_specific;
1866                 real_buffer[4] = data->longlba ? 0x01 : 0;
1867                 real_buffer[5] = 0;
1868                 real_buffer[6] = data->block_descriptor_length >> 8;
1869                 real_buffer[7] = data->block_descriptor_length;
1870
1871                 cmd[0] = MODE_SELECT_10;
1872                 cmd[7] = len >> 8;
1873                 cmd[8] = len;
1874         } else {
1875                 if (len > 255 || data->block_descriptor_length > 255 ||
1876                     data->longlba)
1877                         return -EINVAL;
1878
1879                 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1880                 if (!real_buffer)
1881                         return -ENOMEM;
1882                 memcpy(real_buffer + 4, buffer, len);
1883                 len += 4;
1884                 real_buffer[0] = 0;
1885                 real_buffer[1] = data->medium_type;
1886                 real_buffer[2] = data->device_specific;
1887                 real_buffer[3] = data->block_descriptor_length;
1888                 
1889
1890                 cmd[0] = MODE_SELECT;
1891                 cmd[4] = len;
1892         }
1893
1894         ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1895                                sshdr, timeout, retries, NULL);
1896         kfree(real_buffer);
1897         return ret;
1898 }
1899 EXPORT_SYMBOL_GPL(scsi_mode_select);
1900
1901 /**
1902  *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1903  *      @sdev:  SCSI device to be queried
1904  *      @dbd:   set if mode sense will allow block descriptors to be returned
1905  *      @modepage: mode page being requested
1906  *      @buffer: request buffer (may not be smaller than eight bytes)
1907  *      @len:   length of request buffer.
1908  *      @timeout: command timeout
1909  *      @retries: number of retries before failing
1910  *      @data: returns a structure abstracting the mode header data
1911  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
1912  *              must be SCSI_SENSE_BUFFERSIZE big.
1913  *
1914  *      Returns zero if unsuccessful, or the header offset (either 4
1915  *      or 8 depending on whether a six or ten byte command was
1916  *      issued) if successful.
1917  */
1918 int
1919 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1920                   unsigned char *buffer, int len, int timeout, int retries,
1921                   struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1922 {
1923         unsigned char cmd[12];
1924         int use_10_for_ms;
1925         int header_length;
1926         int result;
1927         struct scsi_sense_hdr my_sshdr;
1928
1929         memset(data, 0, sizeof(*data));
1930         memset(&cmd[0], 0, 12);
1931         cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
1932         cmd[2] = modepage;
1933
1934         /* caller might not be interested in sense, but we need it */
1935         if (!sshdr)
1936                 sshdr = &my_sshdr;
1937
1938  retry:
1939         use_10_for_ms = sdev->use_10_for_ms;
1940
1941         if (use_10_for_ms) {
1942                 if (len < 8)
1943                         len = 8;
1944
1945                 cmd[0] = MODE_SENSE_10;
1946                 cmd[8] = len;
1947                 header_length = 8;
1948         } else {
1949                 if (len < 4)
1950                         len = 4;
1951
1952                 cmd[0] = MODE_SENSE;
1953                 cmd[4] = len;
1954                 header_length = 4;
1955         }
1956
1957         memset(buffer, 0, len);
1958
1959         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1960                                   sshdr, timeout, retries, NULL);
1961
1962         /* This code looks awful: what it's doing is making sure an
1963          * ILLEGAL REQUEST sense return identifies the actual command
1964          * byte as the problem.  MODE_SENSE commands can return
1965          * ILLEGAL REQUEST if the code page isn't supported */
1966
1967         if (use_10_for_ms && !scsi_status_is_good(result) &&
1968             (driver_byte(result) & DRIVER_SENSE)) {
1969                 if (scsi_sense_valid(sshdr)) {
1970                         if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1971                             (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1972                                 /* 
1973                                  * Invalid command operation code
1974                                  */
1975                                 sdev->use_10_for_ms = 0;
1976                                 goto retry;
1977                         }
1978                 }
1979         }
1980
1981         if(scsi_status_is_good(result)) {
1982                 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1983                              (modepage == 6 || modepage == 8))) {
1984                         /* Initio breakage? */
1985                         header_length = 0;
1986                         data->length = 13;
1987                         data->medium_type = 0;
1988                         data->device_specific = 0;
1989                         data->longlba = 0;
1990                         data->block_descriptor_length = 0;
1991                 } else if(use_10_for_ms) {
1992                         data->length = buffer[0]*256 + buffer[1] + 2;
1993                         data->medium_type = buffer[2];
1994                         data->device_specific = buffer[3];
1995                         data->longlba = buffer[4] & 0x01;
1996                         data->block_descriptor_length = buffer[6]*256
1997                                 + buffer[7];
1998                 } else {
1999                         data->length = buffer[0] + 1;
2000                         data->medium_type = buffer[1];
2001                         data->device_specific = buffer[2];
2002                         data->block_descriptor_length = buffer[3];
2003                 }
2004                 data->header_length = header_length;
2005         }
2006
2007         return result;
2008 }
2009 EXPORT_SYMBOL(scsi_mode_sense);
2010
2011 /**
2012  *      scsi_test_unit_ready - test if unit is ready
2013  *      @sdev:  scsi device to change the state of.
2014  *      @timeout: command timeout
2015  *      @retries: number of retries before failing
2016  *      @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2017  *              returning sense. Make sure that this is cleared before passing
2018  *              in.
2019  *
2020  *      Returns zero if unsuccessful or an error if TUR failed.  For
2021  *      removable media, UNIT_ATTENTION sets ->changed flag.
2022  **/
2023 int
2024 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2025                      struct scsi_sense_hdr *sshdr_external)
2026 {
2027         char cmd[] = {
2028                 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2029         };
2030         struct scsi_sense_hdr *sshdr;
2031         int result;
2032
2033         if (!sshdr_external)
2034                 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2035         else
2036                 sshdr = sshdr_external;
2037
2038         /* try to eat the UNIT_ATTENTION if there are enough retries */
2039         do {
2040                 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2041                                           timeout, retries, NULL);
2042                 if (sdev->removable && scsi_sense_valid(sshdr) &&
2043                     sshdr->sense_key == UNIT_ATTENTION)
2044                         sdev->changed = 1;
2045         } while (scsi_sense_valid(sshdr) &&
2046                  sshdr->sense_key == UNIT_ATTENTION && --retries);
2047
2048         if (!sshdr_external)
2049                 kfree(sshdr);
2050         return result;
2051 }
2052 EXPORT_SYMBOL(scsi_test_unit_ready);
2053
2054 /**
2055  *      scsi_device_set_state - Take the given device through the device state model.
2056  *      @sdev:  scsi device to change the state of.
2057  *      @state: state to change to.
2058  *
2059  *      Returns zero if unsuccessful or an error if the requested 
2060  *      transition is illegal.
2061  */
2062 int
2063 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2064 {
2065         enum scsi_device_state oldstate = sdev->sdev_state;
2066
2067         if (state == oldstate)
2068                 return 0;
2069
2070         switch (state) {
2071         case SDEV_CREATED:
2072                 switch (oldstate) {
2073                 case SDEV_CREATED_BLOCK:
2074                         break;
2075                 default:
2076                         goto illegal;
2077                 }
2078                 break;
2079                         
2080         case SDEV_RUNNING:
2081                 switch (oldstate) {
2082                 case SDEV_CREATED:
2083                 case SDEV_OFFLINE:
2084                 case SDEV_QUIESCE:
2085                 case SDEV_BLOCK:
2086                         break;
2087                 default:
2088                         goto illegal;
2089                 }
2090                 break;
2091
2092         case SDEV_QUIESCE:
2093                 switch (oldstate) {
2094                 case SDEV_RUNNING:
2095                 case SDEV_OFFLINE:
2096                         break;
2097                 default:
2098                         goto illegal;
2099                 }
2100                 break;
2101
2102         case SDEV_OFFLINE:
2103                 switch (oldstate) {
2104                 case SDEV_CREATED:
2105                 case SDEV_RUNNING:
2106                 case SDEV_QUIESCE:
2107                 case SDEV_BLOCK:
2108                         break;
2109                 default:
2110                         goto illegal;
2111                 }
2112                 break;
2113
2114         case SDEV_BLOCK:
2115                 switch (oldstate) {
2116                 case SDEV_RUNNING:
2117                 case SDEV_CREATED_BLOCK:
2118                         break;
2119                 default:
2120                         goto illegal;
2121                 }
2122                 break;
2123
2124         case SDEV_CREATED_BLOCK:
2125                 switch (oldstate) {
2126                 case SDEV_CREATED:
2127                         break;
2128                 default:
2129                         goto illegal;
2130                 }
2131                 break;
2132
2133         case SDEV_CANCEL:
2134                 switch (oldstate) {
2135                 case SDEV_CREATED:
2136                 case SDEV_RUNNING:
2137                 case SDEV_QUIESCE:
2138                 case SDEV_OFFLINE:
2139                 case SDEV_BLOCK:
2140                         break;
2141                 default:
2142                         goto illegal;
2143                 }
2144                 break;
2145
2146         case SDEV_DEL:
2147                 switch (oldstate) {
2148                 case SDEV_CREATED:
2149                 case SDEV_RUNNING:
2150                 case SDEV_OFFLINE:
2151                 case SDEV_CANCEL:
2152                         break;
2153                 default:
2154                         goto illegal;
2155                 }
2156                 break;
2157
2158         }
2159         sdev->sdev_state = state;
2160         return 0;
2161
2162  illegal:
2163         SCSI_LOG_ERROR_RECOVERY(1, 
2164                                 sdev_printk(KERN_ERR, sdev,
2165                                             "Illegal state transition %s->%s\n",
2166                                             scsi_device_state_name(oldstate),
2167                                             scsi_device_state_name(state))
2168                                 );
2169         return -EINVAL;
2170 }
2171 EXPORT_SYMBOL(scsi_device_set_state);
2172
2173 /**
2174  *      sdev_evt_emit - emit a single SCSI device uevent
2175  *      @sdev: associated SCSI device
2176  *      @evt: event to emit
2177  *
2178  *      Send a single uevent (scsi_event) to the associated scsi_device.
2179  */
2180 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2181 {
2182         int idx = 0;
2183         char *envp[3];
2184
2185         switch (evt->evt_type) {
2186         case SDEV_EVT_MEDIA_CHANGE:
2187                 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2188                 break;
2189
2190         default:
2191                 /* do nothing */
2192                 break;
2193         }
2194
2195         envp[idx++] = NULL;
2196
2197         kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2198 }
2199
2200 /**
2201  *      sdev_evt_thread - send a uevent for each scsi event
2202  *      @work: work struct for scsi_device
2203  *
2204  *      Dispatch queued events to their associated scsi_device kobjects
2205  *      as uevents.
2206  */
2207 void scsi_evt_thread(struct work_struct *work)
2208 {
2209         struct scsi_device *sdev;
2210         LIST_HEAD(event_list);
2211
2212         sdev = container_of(work, struct scsi_device, event_work);
2213
2214         while (1) {
2215                 struct scsi_event *evt;
2216                 struct list_head *this, *tmp;
2217                 unsigned long flags;
2218
2219                 spin_lock_irqsave(&sdev->list_lock, flags);
2220                 list_splice_init(&sdev->event_list, &event_list);
2221                 spin_unlock_irqrestore(&sdev->list_lock, flags);
2222
2223                 if (list_empty(&event_list))
2224                         break;
2225
2226                 list_for_each_safe(this, tmp, &event_list) {
2227                         evt = list_entry(this, struct scsi_event, node);
2228                         list_del(&evt->node);
2229                         scsi_evt_emit(sdev, evt);
2230                         kfree(evt);
2231                 }
2232         }
2233 }
2234
2235 /**
2236  *      sdev_evt_send - send asserted event to uevent thread
2237  *      @sdev: scsi_device event occurred on
2238  *      @evt: event to send
2239  *
2240  *      Assert scsi device event asynchronously.
2241  */
2242 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2243 {
2244         unsigned long flags;
2245
2246 #if 0
2247         /* FIXME: currently this check eliminates all media change events
2248          * for polled devices.  Need to update to discriminate between AN
2249          * and polled events */
2250         if (!test_bit(evt->evt_type, sdev->supported_events)) {
2251                 kfree(evt);
2252                 return;
2253         }
2254 #endif
2255
2256         spin_lock_irqsave(&sdev->list_lock, flags);
2257         list_add_tail(&evt->node, &sdev->event_list);
2258         schedule_work(&sdev->event_work);
2259         spin_unlock_irqrestore(&sdev->list_lock, flags);
2260 }
2261 EXPORT_SYMBOL_GPL(sdev_evt_send);
2262
2263 /**
2264  *      sdev_evt_alloc - allocate a new scsi event
2265  *      @evt_type: type of event to allocate
2266  *      @gfpflags: GFP flags for allocation
2267  *
2268  *      Allocates and returns a new scsi_event.
2269  */
2270 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2271                                   gfp_t gfpflags)
2272 {
2273         struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2274         if (!evt)
2275                 return NULL;
2276
2277         evt->evt_type = evt_type;
2278         INIT_LIST_HEAD(&evt->node);
2279
2280         /* evt_type-specific initialization, if any */
2281         switch (evt_type) {
2282         case SDEV_EVT_MEDIA_CHANGE:
2283         default:
2284                 /* do nothing */
2285                 break;
2286         }
2287
2288         return evt;
2289 }
2290 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2291
2292 /**
2293  *      sdev_evt_send_simple - send asserted event to uevent thread
2294  *      @sdev: scsi_device event occurred on
2295  *      @evt_type: type of event to send
2296  *      @gfpflags: GFP flags for allocation
2297  *
2298  *      Assert scsi device event asynchronously, given an event type.
2299  */
2300 void sdev_evt_send_simple(struct scsi_device *sdev,
2301                           enum scsi_device_event evt_type, gfp_t gfpflags)
2302 {
2303         struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2304         if (!evt) {
2305                 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2306                             evt_type);
2307                 return;
2308         }
2309
2310         sdev_evt_send(sdev, evt);
2311 }
2312 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2313
2314 /**
2315  *      scsi_device_quiesce - Block user issued commands.
2316  *      @sdev:  scsi device to quiesce.
2317  *
2318  *      This works by trying to transition to the SDEV_QUIESCE state
2319  *      (which must be a legal transition).  When the device is in this
2320  *      state, only special requests will be accepted, all others will
2321  *      be deferred.  Since special requests may also be requeued requests,
2322  *      a successful return doesn't guarantee the device will be 
2323  *      totally quiescent.
2324  *
2325  *      Must be called with user context, may sleep.
2326  *
2327  *      Returns zero if unsuccessful or an error if not.
2328  */
2329 int
2330 scsi_device_quiesce(struct scsi_device *sdev)
2331 {
2332         int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2333         if (err)
2334                 return err;
2335
2336         scsi_run_queue(sdev->request_queue);
2337         while (sdev->device_busy) {
2338                 msleep_interruptible(200);
2339                 scsi_run_queue(sdev->request_queue);
2340         }
2341         return 0;
2342 }
2343 EXPORT_SYMBOL(scsi_device_quiesce);
2344
2345 /**
2346  *      scsi_device_resume - Restart user issued commands to a quiesced device.
2347  *      @sdev:  scsi device to resume.
2348  *
2349  *      Moves the device from quiesced back to running and restarts the
2350  *      queues.
2351  *
2352  *      Must be called with user context, may sleep.
2353  */
2354 void
2355 scsi_device_resume(struct scsi_device *sdev)
2356 {
2357         if(scsi_device_set_state(sdev, SDEV_RUNNING))
2358                 return;
2359         scsi_run_queue(sdev->request_queue);
2360 }
2361 EXPORT_SYMBOL(scsi_device_resume);
2362
2363 static void
2364 device_quiesce_fn(struct scsi_device *sdev, void *data)
2365 {
2366         scsi_device_quiesce(sdev);
2367 }
2368
2369 void
2370 scsi_target_quiesce(struct scsi_target *starget)
2371 {
2372         starget_for_each_device(starget, NULL, device_quiesce_fn);
2373 }
2374 EXPORT_SYMBOL(scsi_target_quiesce);
2375
2376 static void
2377 device_resume_fn(struct scsi_device *sdev, void *data)
2378 {
2379         scsi_device_resume(sdev);
2380 }
2381
2382 void
2383 scsi_target_resume(struct scsi_target *starget)
2384 {
2385         starget_for_each_device(starget, NULL, device_resume_fn);
2386 }
2387 EXPORT_SYMBOL(scsi_target_resume);
2388
2389 /**
2390  * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2391  * @sdev:       device to block
2392  *
2393  * Block request made by scsi lld's to temporarily stop all
2394  * scsi commands on the specified device.  Called from interrupt
2395  * or normal process context.
2396  *
2397  * Returns zero if successful or error if not
2398  *
2399  * Notes:       
2400  *      This routine transitions the device to the SDEV_BLOCK state
2401  *      (which must be a legal transition).  When the device is in this
2402  *      state, all commands are deferred until the scsi lld reenables
2403  *      the device with scsi_device_unblock or device_block_tmo fires.
2404  *      This routine assumes the host_lock is held on entry.
2405  */
2406 int
2407 scsi_internal_device_block(struct scsi_device *sdev)
2408 {
2409         struct request_queue *q = sdev->request_queue;
2410         unsigned long flags;
2411         int err = 0;
2412
2413         err = scsi_device_set_state(sdev, SDEV_BLOCK);
2414         if (err) {
2415                 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2416
2417                 if (err)
2418                         return err;
2419         }
2420
2421         /* 
2422          * The device has transitioned to SDEV_BLOCK.  Stop the
2423          * block layer from calling the midlayer with this device's
2424          * request queue. 
2425          */
2426         spin_lock_irqsave(q->queue_lock, flags);
2427         blk_stop_queue(q);
2428         spin_unlock_irqrestore(q->queue_lock, flags);
2429
2430         return 0;
2431 }
2432 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2433  
2434 /**
2435  * scsi_internal_device_unblock - resume a device after a block request
2436  * @sdev:       device to resume
2437  *
2438  * Called by scsi lld's or the midlayer to restart the device queue
2439  * for the previously suspended scsi device.  Called from interrupt or
2440  * normal process context.
2441  *
2442  * Returns zero if successful or error if not.
2443  *
2444  * Notes:       
2445  *      This routine transitions the device to the SDEV_RUNNING state
2446  *      (which must be a legal transition) allowing the midlayer to
2447  *      goose the queue for this device.  This routine assumes the 
2448  *      host_lock is held upon entry.
2449  */
2450 int
2451 scsi_internal_device_unblock(struct scsi_device *sdev)
2452 {
2453         struct request_queue *q = sdev->request_queue; 
2454         unsigned long flags;
2455         
2456         /* 
2457          * Try to transition the scsi device to SDEV_RUNNING
2458          * and goose the device queue if successful.  
2459          */
2460         if (sdev->sdev_state == SDEV_BLOCK)
2461                 sdev->sdev_state = SDEV_RUNNING;
2462         else if (sdev->sdev_state == SDEV_CREATED_BLOCK)
2463                 sdev->sdev_state = SDEV_CREATED;
2464         else if (sdev->sdev_state != SDEV_CANCEL &&
2465                  sdev->sdev_state != SDEV_OFFLINE)
2466                 return -EINVAL;
2467
2468         spin_lock_irqsave(q->queue_lock, flags);
2469         blk_start_queue(q);
2470         spin_unlock_irqrestore(q->queue_lock, flags);
2471
2472         return 0;
2473 }
2474 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2475
2476 static void
2477 device_block(struct scsi_device *sdev, void *data)
2478 {
2479         scsi_internal_device_block(sdev);
2480 }
2481
2482 static int
2483 target_block(struct device *dev, void *data)
2484 {
2485         if (scsi_is_target_device(dev))
2486                 starget_for_each_device(to_scsi_target(dev), NULL,
2487                                         device_block);
2488         return 0;
2489 }
2490
2491 void
2492 scsi_target_block(struct device *dev)
2493 {
2494         if (scsi_is_target_device(dev))
2495                 starget_for_each_device(to_scsi_target(dev), NULL,
2496                                         device_block);
2497         else
2498                 device_for_each_child(dev, NULL, target_block);
2499 }
2500 EXPORT_SYMBOL_GPL(scsi_target_block);
2501
2502 static void
2503 device_unblock(struct scsi_device *sdev, void *data)
2504 {
2505         scsi_internal_device_unblock(sdev);
2506 }
2507
2508 static int
2509 target_unblock(struct device *dev, void *data)
2510 {
2511         if (scsi_is_target_device(dev))
2512                 starget_for_each_device(to_scsi_target(dev), NULL,
2513                                         device_unblock);
2514         return 0;
2515 }
2516
2517 void
2518 scsi_target_unblock(struct device *dev)
2519 {
2520         if (scsi_is_target_device(dev))
2521                 starget_for_each_device(to_scsi_target(dev), NULL,
2522                                         device_unblock);
2523         else
2524                 device_for_each_child(dev, NULL, target_unblock);
2525 }
2526 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2527
2528 /**
2529  * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2530  * @sgl:        scatter-gather list
2531  * @sg_count:   number of segments in sg
2532  * @offset:     offset in bytes into sg, on return offset into the mapped area
2533  * @len:        bytes to map, on return number of bytes mapped
2534  *
2535  * Returns virtual address of the start of the mapped page
2536  */
2537 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2538                           size_t *offset, size_t *len)
2539 {
2540         int i;
2541         size_t sg_len = 0, len_complete = 0;
2542         struct scatterlist *sg;
2543         struct page *page;
2544
2545         WARN_ON(!irqs_disabled());
2546
2547         for_each_sg(sgl, sg, sg_count, i) {
2548                 len_complete = sg_len; /* Complete sg-entries */
2549                 sg_len += sg->length;
2550                 if (sg_len > *offset)
2551                         break;
2552         }
2553
2554         if (unlikely(i == sg_count)) {
2555                 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2556                         "elements %d\n",
2557                        __func__, sg_len, *offset, sg_count);
2558                 WARN_ON(1);
2559                 return NULL;
2560         }
2561
2562         /* Offset starting from the beginning of first page in this sg-entry */
2563         *offset = *offset - len_complete + sg->offset;
2564
2565         /* Assumption: contiguous pages can be accessed as "page + i" */
2566         page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2567         *offset &= ~PAGE_MASK;
2568
2569         /* Bytes in this sg-entry from *offset to the end of the page */
2570         sg_len = PAGE_SIZE - *offset;
2571         if (*len > sg_len)
2572                 *len = sg_len;
2573
2574         return kmap_atomic(page, KM_BIO_SRC_IRQ);
2575 }
2576 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2577
2578 /**
2579  * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2580  * @virt:       virtual address to be unmapped
2581  */
2582 void scsi_kunmap_atomic_sg(void *virt)
2583 {
2584         kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2585 }
2586 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);