Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris...
[linux-2.6] / 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 static void scsi_run_queue(struct request_queue *q);
71
72 /*
73  * Function:    scsi_unprep_request()
74  *
75  * Purpose:     Remove all preparation done for a request, including its
76  *              associated scsi_cmnd, so that it can be requeued.
77  *
78  * Arguments:   req     - request to unprepare
79  *
80  * Lock status: Assumed that no locks are held upon entry.
81  *
82  * Returns:     Nothing.
83  */
84 static void scsi_unprep_request(struct request *req)
85 {
86         struct scsi_cmnd *cmd = req->special;
87
88         req->cmd_flags &= ~REQ_DONTPREP;
89         req->special = NULL;
90
91         scsi_put_command(cmd);
92 }
93
94 /**
95  * __scsi_queue_insert - private queue insertion
96  * @cmd: The SCSI command being requeued
97  * @reason:  The reason for the requeue
98  * @unbusy: Whether the queue should be unbusied
99  *
100  * This is a private queue insertion.  The public interface
101  * scsi_queue_insert() always assumes the queue should be unbusied
102  * because it's always called before the completion.  This function is
103  * for a requeue after completion, which should only occur in this
104  * file.
105  */
106 static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
107 {
108         struct Scsi_Host *host = cmd->device->host;
109         struct scsi_device *device = cmd->device;
110         struct scsi_target *starget = scsi_target(device);
111         struct request_queue *q = device->request_queue;
112         unsigned long flags;
113
114         SCSI_LOG_MLQUEUE(1,
115                  printk("Inserting command %p into mlqueue\n", cmd));
116
117         /*
118          * Set the appropriate busy bit for the device/host.
119          *
120          * If the host/device isn't busy, assume that something actually
121          * completed, and that we should be able to queue a command now.
122          *
123          * Note that the prior mid-layer assumption that any host could
124          * always queue at least one command is now broken.  The mid-layer
125          * will implement a user specifiable stall (see
126          * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
127          * if a command is requeued with no other commands outstanding
128          * either for the device or for the host.
129          */
130         switch (reason) {
131         case SCSI_MLQUEUE_HOST_BUSY:
132                 host->host_blocked = host->max_host_blocked;
133                 break;
134         case SCSI_MLQUEUE_DEVICE_BUSY:
135                 device->device_blocked = device->max_device_blocked;
136                 break;
137         case SCSI_MLQUEUE_TARGET_BUSY:
138                 starget->target_blocked = starget->max_target_blocked;
139                 break;
140         }
141
142         /*
143          * Decrement the counters, since these commands are no longer
144          * active on the host/device.
145          */
146         if (unbusy)
147                 scsi_device_unbusy(device);
148
149         /*
150          * Requeue this command.  It will go before all other commands
151          * that are already in the queue.
152          *
153          * NOTE: there is magic here about the way the queue is plugged if
154          * we have no outstanding commands.
155          * 
156          * Although we *don't* plug the queue, we call the request
157          * function.  The SCSI request function detects the blocked condition
158          * and plugs the queue appropriately.
159          */
160         spin_lock_irqsave(q->queue_lock, flags);
161         blk_requeue_request(q, cmd->request);
162         spin_unlock_irqrestore(q->queue_lock, flags);
163
164         scsi_run_queue(q);
165
166         return 0;
167 }
168
169 /*
170  * Function:    scsi_queue_insert()
171  *
172  * Purpose:     Insert a command in the midlevel queue.
173  *
174  * Arguments:   cmd    - command that we are adding to queue.
175  *              reason - why we are inserting command to queue.
176  *
177  * Lock status: Assumed that lock is not held upon entry.
178  *
179  * Returns:     Nothing.
180  *
181  * Notes:       We do this for one of two cases.  Either the host is busy
182  *              and it cannot accept any more commands for the time being,
183  *              or the device returned QUEUE_FULL and can accept no more
184  *              commands.
185  * Notes:       This could be called either from an interrupt context or a
186  *              normal process context.
187  */
188 int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
189 {
190         return __scsi_queue_insert(cmd, reason, 1);
191 }
192 /**
193  * scsi_execute - insert request and wait for the result
194  * @sdev:       scsi device
195  * @cmd:        scsi command
196  * @data_direction: data direction
197  * @buffer:     data buffer
198  * @bufflen:    len of buffer
199  * @sense:      optional sense buffer
200  * @timeout:    request timeout in seconds
201  * @retries:    number of times to retry request
202  * @flags:      or into request flags;
203  * @resid:      optional residual length
204  *
205  * returns the req->errors value which is the scsi_cmnd result
206  * field.
207  */
208 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
209                  int data_direction, void *buffer, unsigned bufflen,
210                  unsigned char *sense, int timeout, int retries, int flags,
211                  int *resid)
212 {
213         struct request *req;
214         int write = (data_direction == DMA_TO_DEVICE);
215         int ret = DRIVER_ERROR << 24;
216
217         req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
218
219         if (bufflen &&  blk_rq_map_kern(sdev->request_queue, req,
220                                         buffer, bufflen, __GFP_WAIT))
221                 goto out;
222
223         req->cmd_len = COMMAND_SIZE(cmd[0]);
224         memcpy(req->cmd, cmd, req->cmd_len);
225         req->sense = sense;
226         req->sense_len = 0;
227         req->retries = retries;
228         req->timeout = timeout;
229         req->cmd_type = REQ_TYPE_BLOCK_PC;
230         req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
231
232         /*
233          * head injection *required* here otherwise quiesce won't work
234          */
235         blk_execute_rq(req->q, NULL, req, 1);
236
237         /*
238          * Some devices (USB mass-storage in particular) may transfer
239          * garbage data together with a residue indicating that the data
240          * is invalid.  Prevent the garbage from being misinterpreted
241          * and prevent security leaks by zeroing out the excess data.
242          */
243         if (unlikely(req->data_len > 0 && req->data_len <= bufflen))
244                 memset(buffer + (bufflen - req->data_len), 0, req->data_len);
245
246         if (resid)
247                 *resid = req->data_len;
248         ret = req->errors;
249  out:
250         blk_put_request(req);
251
252         return ret;
253 }
254 EXPORT_SYMBOL(scsi_execute);
255
256
257 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
258                      int data_direction, void *buffer, unsigned bufflen,
259                      struct scsi_sense_hdr *sshdr, int timeout, int retries,
260                      int *resid)
261 {
262         char *sense = NULL;
263         int result;
264         
265         if (sshdr) {
266                 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
267                 if (!sense)
268                         return DRIVER_ERROR << 24;
269         }
270         result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
271                               sense, timeout, retries, 0, resid);
272         if (sshdr)
273                 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
274
275         kfree(sense);
276         return result;
277 }
278 EXPORT_SYMBOL(scsi_execute_req);
279
280 struct scsi_io_context {
281         void *data;
282         void (*done)(void *data, char *sense, int result, int resid);
283         char sense[SCSI_SENSE_BUFFERSIZE];
284 };
285
286 static struct kmem_cache *scsi_io_context_cache;
287
288 static void scsi_end_async(struct request *req, int uptodate)
289 {
290         struct scsi_io_context *sioc = req->end_io_data;
291
292         if (sioc->done)
293                 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
294
295         kmem_cache_free(scsi_io_context_cache, sioc);
296         __blk_put_request(req->q, req);
297 }
298
299 static int scsi_merge_bio(struct request *rq, struct bio *bio)
300 {
301         struct request_queue *q = rq->q;
302
303         bio->bi_flags &= ~(1 << BIO_SEG_VALID);
304         if (rq_data_dir(rq) == WRITE)
305                 bio->bi_rw |= (1 << BIO_RW);
306         blk_queue_bounce(q, &bio);
307
308         return blk_rq_append_bio(q, rq, bio);
309 }
310
311 static void scsi_bi_endio(struct bio *bio, int error)
312 {
313         bio_put(bio);
314 }
315
316 /**
317  * scsi_req_map_sg - map a scatterlist into a request
318  * @rq:         request to fill
319  * @sgl:        scatterlist
320  * @nsegs:      number of elements
321  * @bufflen:    len of buffer
322  * @gfp:        memory allocation flags
323  *
324  * scsi_req_map_sg maps a scatterlist into a request so that the
325  * request can be sent to the block layer. We do not trust the scatterlist
326  * sent to use, as some ULDs use that struct to only organize the pages.
327  */
328 static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
329                            int nsegs, unsigned bufflen, gfp_t gfp)
330 {
331         struct request_queue *q = rq->q;
332         int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
333         unsigned int data_len = bufflen, len, bytes, off;
334         struct scatterlist *sg;
335         struct page *page;
336         struct bio *bio = NULL;
337         int i, err, nr_vecs = 0;
338
339         for_each_sg(sgl, sg, nsegs, i) {
340                 page = sg_page(sg);
341                 off = sg->offset;
342                 len = sg->length;
343
344                 while (len > 0 && data_len > 0) {
345                         /*
346                          * sg sends a scatterlist that is larger than
347                          * the data_len it wants transferred for certain
348                          * IO sizes
349                          */
350                         bytes = min_t(unsigned int, len, PAGE_SIZE - off);
351                         bytes = min(bytes, data_len);
352
353                         if (!bio) {
354                                 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
355                                 nr_pages -= nr_vecs;
356
357                                 bio = bio_alloc(gfp, nr_vecs);
358                                 if (!bio) {
359                                         err = -ENOMEM;
360                                         goto free_bios;
361                                 }
362                                 bio->bi_end_io = scsi_bi_endio;
363                         }
364
365                         if (bio_add_pc_page(q, bio, page, bytes, off) !=
366                             bytes) {
367                                 bio_put(bio);
368                                 err = -EINVAL;
369                                 goto free_bios;
370                         }
371
372                         if (bio->bi_vcnt >= nr_vecs) {
373                                 err = scsi_merge_bio(rq, bio);
374                                 if (err) {
375                                         bio_endio(bio, 0);
376                                         goto free_bios;
377                                 }
378                                 bio = NULL;
379                         }
380
381                         page++;
382                         len -= bytes;
383                         data_len -=bytes;
384                         off = 0;
385                 }
386         }
387
388         rq->buffer = rq->data = NULL;
389         rq->data_len = bufflen;
390         return 0;
391
392 free_bios:
393         while ((bio = rq->bio) != NULL) {
394                 rq->bio = bio->bi_next;
395                 /*
396                  * call endio instead of bio_put incase it was bounced
397                  */
398                 bio_endio(bio, 0);
399         }
400
401         return err;
402 }
403
404 /**
405  * scsi_execute_async - insert request
406  * @sdev:       scsi device
407  * @cmd:        scsi command
408  * @cmd_len:    length of scsi cdb
409  * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
410  * @buffer:     data buffer (this can be a kernel buffer or scatterlist)
411  * @bufflen:    len of buffer
412  * @use_sg:     if buffer is a scatterlist this is the number of elements
413  * @timeout:    request timeout in seconds
414  * @retries:    number of times to retry request
415  * @privdata:   data passed to done()
416  * @done:       callback function when done
417  * @gfp:        memory allocation flags
418  */
419 int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
420                        int cmd_len, int data_direction, void *buffer, unsigned bufflen,
421                        int use_sg, int timeout, int retries, void *privdata,
422                        void (*done)(void *, char *, int, int), gfp_t gfp)
423 {
424         struct request *req;
425         struct scsi_io_context *sioc;
426         int err = 0;
427         int write = (data_direction == DMA_TO_DEVICE);
428
429         sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
430         if (!sioc)
431                 return DRIVER_ERROR << 24;
432
433         req = blk_get_request(sdev->request_queue, write, gfp);
434         if (!req)
435                 goto free_sense;
436         req->cmd_type = REQ_TYPE_BLOCK_PC;
437         req->cmd_flags |= REQ_QUIET;
438
439         if (use_sg)
440                 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
441         else if (bufflen)
442                 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
443
444         if (err)
445                 goto free_req;
446
447         req->cmd_len = cmd_len;
448         memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
449         memcpy(req->cmd, cmd, req->cmd_len);
450         req->sense = sioc->sense;
451         req->sense_len = 0;
452         req->timeout = timeout;
453         req->retries = retries;
454         req->end_io_data = sioc;
455
456         sioc->data = privdata;
457         sioc->done = done;
458
459         blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
460         return 0;
461
462 free_req:
463         blk_put_request(req);
464 free_sense:
465         kmem_cache_free(scsi_io_context_cache, sioc);
466         return DRIVER_ERROR << 24;
467 }
468 EXPORT_SYMBOL_GPL(scsi_execute_async);
469
470 /*
471  * Function:    scsi_init_cmd_errh()
472  *
473  * Purpose:     Initialize cmd fields related to error handling.
474  *
475  * Arguments:   cmd     - command that is ready to be queued.
476  *
477  * Notes:       This function has the job of initializing a number of
478  *              fields related to error handling.   Typically this will
479  *              be called once for each command, as required.
480  */
481 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
482 {
483         cmd->serial_number = 0;
484         scsi_set_resid(cmd, 0);
485         memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
486         if (cmd->cmd_len == 0)
487                 cmd->cmd_len = scsi_command_size(cmd->cmnd);
488 }
489
490 void scsi_device_unbusy(struct scsi_device *sdev)
491 {
492         struct Scsi_Host *shost = sdev->host;
493         struct scsi_target *starget = scsi_target(sdev);
494         unsigned long flags;
495
496         spin_lock_irqsave(shost->host_lock, flags);
497         shost->host_busy--;
498         starget->target_busy--;
499         if (unlikely(scsi_host_in_recovery(shost) &&
500                      (shost->host_failed || shost->host_eh_scheduled)))
501                 scsi_eh_wakeup(shost);
502         spin_unlock(shost->host_lock);
503         spin_lock(sdev->request_queue->queue_lock);
504         sdev->device_busy--;
505         spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
506 }
507
508 /*
509  * Called for single_lun devices on IO completion. Clear starget_sdev_user,
510  * and call blk_run_queue for all the scsi_devices on the target -
511  * including current_sdev first.
512  *
513  * Called with *no* scsi locks held.
514  */
515 static void scsi_single_lun_run(struct scsi_device *current_sdev)
516 {
517         struct Scsi_Host *shost = current_sdev->host;
518         struct scsi_device *sdev, *tmp;
519         struct scsi_target *starget = scsi_target(current_sdev);
520         unsigned long flags;
521
522         spin_lock_irqsave(shost->host_lock, flags);
523         starget->starget_sdev_user = NULL;
524         spin_unlock_irqrestore(shost->host_lock, flags);
525
526         /*
527          * Call blk_run_queue for all LUNs on the target, starting with
528          * current_sdev. We race with others (to set starget_sdev_user),
529          * but in most cases, we will be first. Ideally, each LU on the
530          * target would get some limited time or requests on the target.
531          */
532         blk_run_queue(current_sdev->request_queue);
533
534         spin_lock_irqsave(shost->host_lock, flags);
535         if (starget->starget_sdev_user)
536                 goto out;
537         list_for_each_entry_safe(sdev, tmp, &starget->devices,
538                         same_target_siblings) {
539                 if (sdev == current_sdev)
540                         continue;
541                 if (scsi_device_get(sdev))
542                         continue;
543
544                 spin_unlock_irqrestore(shost->host_lock, flags);
545                 blk_run_queue(sdev->request_queue);
546                 spin_lock_irqsave(shost->host_lock, flags);
547         
548                 scsi_device_put(sdev);
549         }
550  out:
551         spin_unlock_irqrestore(shost->host_lock, flags);
552 }
553
554 static inline int scsi_device_is_busy(struct scsi_device *sdev)
555 {
556         if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
557                 return 1;
558
559         return 0;
560 }
561
562 static inline int scsi_target_is_busy(struct scsi_target *starget)
563 {
564         return ((starget->can_queue > 0 &&
565                  starget->target_busy >= starget->can_queue) ||
566                  starget->target_blocked);
567 }
568
569 static inline int scsi_host_is_busy(struct Scsi_Host *shost)
570 {
571         if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
572             shost->host_blocked || shost->host_self_blocked)
573                 return 1;
574
575         return 0;
576 }
577
578 /*
579  * Function:    scsi_run_queue()
580  *
581  * Purpose:     Select a proper request queue to serve next
582  *
583  * Arguments:   q       - last request's queue
584  *
585  * Returns:     Nothing
586  *
587  * Notes:       The previous command was completely finished, start
588  *              a new one if possible.
589  */
590 static void scsi_run_queue(struct request_queue *q)
591 {
592         struct scsi_device *sdev = q->queuedata;
593         struct Scsi_Host *shost = sdev->host;
594         LIST_HEAD(starved_list);
595         unsigned long flags;
596
597         if (scsi_target(sdev)->single_lun)
598                 scsi_single_lun_run(sdev);
599
600         spin_lock_irqsave(shost->host_lock, flags);
601         list_splice_init(&shost->starved_list, &starved_list);
602
603         while (!list_empty(&starved_list)) {
604                 int flagset;
605
606                 /*
607                  * As long as shost is accepting commands and we have
608                  * starved queues, call blk_run_queue. scsi_request_fn
609                  * drops the queue_lock and can add us back to the
610                  * starved_list.
611                  *
612                  * host_lock protects the starved_list and starved_entry.
613                  * scsi_request_fn must get the host_lock before checking
614                  * or modifying starved_list or starved_entry.
615                  */
616                 if (scsi_host_is_busy(shost))
617                         break;
618
619                 sdev = list_entry(starved_list.next,
620                                   struct scsi_device, starved_entry);
621                 list_del_init(&sdev->starved_entry);
622                 if (scsi_target_is_busy(scsi_target(sdev))) {
623                         list_move_tail(&sdev->starved_entry,
624                                        &shost->starved_list);
625                         continue;
626                 }
627
628                 spin_unlock(shost->host_lock);
629
630                 spin_lock(sdev->request_queue->queue_lock);
631                 flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
632                                 !test_bit(QUEUE_FLAG_REENTER,
633                                         &sdev->request_queue->queue_flags);
634                 if (flagset)
635                         queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
636                 __blk_run_queue(sdev->request_queue);
637                 if (flagset)
638                         queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
639                 spin_unlock(sdev->request_queue->queue_lock);
640
641                 spin_lock(shost->host_lock);
642         }
643         /* put any unprocessed entries back */
644         list_splice(&starved_list, &shost->starved_list);
645         spin_unlock_irqrestore(shost->host_lock, flags);
646
647         blk_run_queue(q);
648 }
649
650 /*
651  * Function:    scsi_requeue_command()
652  *
653  * Purpose:     Handle post-processing of completed commands.
654  *
655  * Arguments:   q       - queue to operate on
656  *              cmd     - command that may need to be requeued.
657  *
658  * Returns:     Nothing
659  *
660  * Notes:       After command completion, there may be blocks left
661  *              over which weren't finished by the previous command
662  *              this can be for a number of reasons - the main one is
663  *              I/O errors in the middle of the request, in which case
664  *              we need to request the blocks that come after the bad
665  *              sector.
666  * Notes:       Upon return, cmd is a stale pointer.
667  */
668 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
669 {
670         struct request *req = cmd->request;
671         unsigned long flags;
672
673         spin_lock_irqsave(q->queue_lock, flags);
674         scsi_unprep_request(req);
675         blk_requeue_request(q, req);
676         spin_unlock_irqrestore(q->queue_lock, flags);
677
678         scsi_run_queue(q);
679 }
680
681 void scsi_next_command(struct scsi_cmnd *cmd)
682 {
683         struct scsi_device *sdev = cmd->device;
684         struct request_queue *q = sdev->request_queue;
685
686         /* need to hold a reference on the device before we let go of the cmd */
687         get_device(&sdev->sdev_gendev);
688
689         scsi_put_command(cmd);
690         scsi_run_queue(q);
691
692         /* ok to remove device now */
693         put_device(&sdev->sdev_gendev);
694 }
695
696 void scsi_run_host_queues(struct Scsi_Host *shost)
697 {
698         struct scsi_device *sdev;
699
700         shost_for_each_device(sdev, shost)
701                 scsi_run_queue(sdev->request_queue);
702 }
703
704 static void __scsi_release_buffers(struct scsi_cmnd *, int);
705
706 /*
707  * Function:    scsi_end_request()
708  *
709  * Purpose:     Post-processing of completed commands (usually invoked at end
710  *              of upper level post-processing and scsi_io_completion).
711  *
712  * Arguments:   cmd      - command that is complete.
713  *              error    - 0 if I/O indicates success, < 0 for I/O error.
714  *              bytes    - number of bytes of completed I/O
715  *              requeue  - indicates whether we should requeue leftovers.
716  *
717  * Lock status: Assumed that lock is not held upon entry.
718  *
719  * Returns:     cmd if requeue required, NULL otherwise.
720  *
721  * Notes:       This is called for block device requests in order to
722  *              mark some number of sectors as complete.
723  * 
724  *              We are guaranteeing that the request queue will be goosed
725  *              at some point during this call.
726  * Notes:       If cmd was requeued, upon return it will be a stale pointer.
727  */
728 static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
729                                           int bytes, int requeue)
730 {
731         struct request_queue *q = cmd->device->request_queue;
732         struct request *req = cmd->request;
733
734         /*
735          * If there are blocks left over at the end, set up the command
736          * to queue the remainder of them.
737          */
738         if (blk_end_request(req, error, bytes)) {
739                 int leftover = (req->hard_nr_sectors << 9);
740
741                 if (blk_pc_request(req))
742                         leftover = req->data_len;
743
744                 /* kill remainder if no retrys */
745                 if (error && scsi_noretry_cmd(cmd))
746                         blk_end_request(req, error, leftover);
747                 else {
748                         if (requeue) {
749                                 /*
750                                  * Bleah.  Leftovers again.  Stick the
751                                  * leftovers in the front of the
752                                  * queue, and goose the queue again.
753                                  */
754                                 scsi_release_buffers(cmd);
755                                 scsi_requeue_command(q, cmd);
756                                 cmd = NULL;
757                         }
758                         return cmd;
759                 }
760         }
761
762         /*
763          * This will goose the queue request function at the end, so we don't
764          * need to worry about launching another command.
765          */
766         __scsi_release_buffers(cmd, 0);
767         scsi_next_command(cmd);
768         return NULL;
769 }
770
771 static inline unsigned int scsi_sgtable_index(unsigned short nents)
772 {
773         unsigned int index;
774
775         BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
776
777         if (nents <= 8)
778                 index = 0;
779         else
780                 index = get_count_order(nents) - 3;
781
782         return index;
783 }
784
785 static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
786 {
787         struct scsi_host_sg_pool *sgp;
788
789         sgp = scsi_sg_pools + scsi_sgtable_index(nents);
790         mempool_free(sgl, sgp->pool);
791 }
792
793 static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
794 {
795         struct scsi_host_sg_pool *sgp;
796
797         sgp = scsi_sg_pools + scsi_sgtable_index(nents);
798         return mempool_alloc(sgp->pool, gfp_mask);
799 }
800
801 static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
802                               gfp_t gfp_mask)
803 {
804         int ret;
805
806         BUG_ON(!nents);
807
808         ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
809                                gfp_mask, scsi_sg_alloc);
810         if (unlikely(ret))
811                 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
812                                 scsi_sg_free);
813
814         return ret;
815 }
816
817 static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
818 {
819         __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
820 }
821
822 static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
823 {
824
825         if (cmd->sdb.table.nents)
826                 scsi_free_sgtable(&cmd->sdb);
827
828         memset(&cmd->sdb, 0, sizeof(cmd->sdb));
829
830         if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
831                 struct scsi_data_buffer *bidi_sdb =
832                         cmd->request->next_rq->special;
833                 scsi_free_sgtable(bidi_sdb);
834                 kmem_cache_free(scsi_sdb_cache, bidi_sdb);
835                 cmd->request->next_rq->special = NULL;
836         }
837
838         if (scsi_prot_sg_count(cmd))
839                 scsi_free_sgtable(cmd->prot_sdb);
840 }
841
842 /*
843  * Function:    scsi_release_buffers()
844  *
845  * Purpose:     Completion processing for block device I/O requests.
846  *
847  * Arguments:   cmd     - command that we are bailing.
848  *
849  * Lock status: Assumed that no lock is held upon entry.
850  *
851  * Returns:     Nothing
852  *
853  * Notes:       In the event that an upper level driver rejects a
854  *              command, we must release resources allocated during
855  *              the __init_io() function.  Primarily this would involve
856  *              the scatter-gather table, and potentially any bounce
857  *              buffers.
858  */
859 void scsi_release_buffers(struct scsi_cmnd *cmd)
860 {
861         __scsi_release_buffers(cmd, 1);
862 }
863 EXPORT_SYMBOL(scsi_release_buffers);
864
865 /*
866  * Bidi commands Must be complete as a whole, both sides at once.
867  * If part of the bytes were written and lld returned
868  * scsi_in()->resid and/or scsi_out()->resid this information will be left
869  * in req->data_len and req->next_rq->data_len. The upper-layer driver can
870  * decide what to do with this information.
871  */
872 static void scsi_end_bidi_request(struct scsi_cmnd *cmd)
873 {
874         struct request *req = cmd->request;
875         unsigned int dlen = req->data_len;
876         unsigned int next_dlen = req->next_rq->data_len;
877
878         req->data_len = scsi_out(cmd)->resid;
879         req->next_rq->data_len = scsi_in(cmd)->resid;
880
881         /* The req and req->next_rq have not been completed */
882         BUG_ON(blk_end_bidi_request(req, 0, dlen, next_dlen));
883
884         scsi_release_buffers(cmd);
885
886         /*
887          * This will goose the queue request function at the end, so we don't
888          * need to worry about launching another command.
889          */
890         scsi_next_command(cmd);
891 }
892
893 /*
894  * Function:    scsi_io_completion()
895  *
896  * Purpose:     Completion processing for block device I/O requests.
897  *
898  * Arguments:   cmd   - command that is finished.
899  *
900  * Lock status: Assumed that no lock is held upon entry.
901  *
902  * Returns:     Nothing
903  *
904  * Notes:       This function is matched in terms of capabilities to
905  *              the function that created the scatter-gather list.
906  *              In other words, if there are no bounce buffers
907  *              (the normal case for most drivers), we don't need
908  *              the logic to deal with cleaning up afterwards.
909  *
910  *              We must call scsi_end_request().  This will finish off
911  *              the specified number of sectors.  If we are done, the
912  *              command block will be released and the queue function
913  *              will be goosed.  If we are not done then we have to
914  *              figure out what to do next:
915  *
916  *              a) We can call scsi_requeue_command().  The request
917  *                 will be unprepared and put back on the queue.  Then
918  *                 a new command will be created for it.  This should
919  *                 be used if we made forward progress, or if we want
920  *                 to switch from READ(10) to READ(6) for example.
921  *
922  *              b) We can call scsi_queue_insert().  The request will
923  *                 be put back on the queue and retried using the same
924  *                 command as before, possibly after a delay.
925  *
926  *              c) We can call blk_end_request() with -EIO to fail
927  *                 the remainder of the request.
928  */
929 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
930 {
931         int result = cmd->result;
932         int this_count;
933         struct request_queue *q = cmd->device->request_queue;
934         struct request *req = cmd->request;
935         int error = 0;
936         struct scsi_sense_hdr sshdr;
937         int sense_valid = 0;
938         int sense_deferred = 0;
939         enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
940               ACTION_DELAYED_RETRY} action;
941         char *description = NULL;
942
943         if (result) {
944                 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
945                 if (sense_valid)
946                         sense_deferred = scsi_sense_is_deferred(&sshdr);
947         }
948
949         if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
950                 req->errors = result;
951                 if (result) {
952                         if (sense_valid && req->sense) {
953                                 /*
954                                  * SG_IO wants current and deferred errors
955                                  */
956                                 int len = 8 + cmd->sense_buffer[7];
957
958                                 if (len > SCSI_SENSE_BUFFERSIZE)
959                                         len = SCSI_SENSE_BUFFERSIZE;
960                                 memcpy(req->sense, cmd->sense_buffer,  len);
961                                 req->sense_len = len;
962                         }
963                         if (!sense_deferred)
964                                 error = -EIO;
965                 }
966                 if (scsi_bidi_cmnd(cmd)) {
967                         /* will also release_buffers */
968                         scsi_end_bidi_request(cmd);
969                         return;
970                 }
971                 req->data_len = scsi_get_resid(cmd);
972         }
973
974         BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */
975
976         /*
977          * Next deal with any sectors which we were able to correctly
978          * handle.
979          */
980         SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, "
981                                       "%d bytes done.\n",
982                                       req->nr_sectors, good_bytes));
983
984         /* A number of bytes were successfully read.  If there
985          * are leftovers and there is some kind of error
986          * (result != 0), retry the rest.
987          */
988         if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
989                 return;
990         this_count = blk_rq_bytes(req);
991
992         error = -EIO;
993
994         if (host_byte(result) == DID_RESET) {
995                 /* Third party bus reset or reset for error recovery
996                  * reasons.  Just retry the command and see what
997                  * happens.
998                  */
999                 action = ACTION_RETRY;
1000         } else if (sense_valid && !sense_deferred) {
1001                 switch (sshdr.sense_key) {
1002                 case UNIT_ATTENTION:
1003                         if (cmd->device->removable) {
1004                                 /* Detected disc change.  Set a bit
1005                                  * and quietly refuse further access.
1006                                  */
1007                                 cmd->device->changed = 1;
1008                                 description = "Media Changed";
1009                                 action = ACTION_FAIL;
1010                         } else {
1011                                 /* Must have been a power glitch, or a
1012                                  * bus reset.  Could not have been a
1013                                  * media change, so we just retry the
1014                                  * command and see what happens.
1015                                  */
1016                                 action = ACTION_RETRY;
1017                         }
1018                         break;
1019                 case ILLEGAL_REQUEST:
1020                         /* If we had an ILLEGAL REQUEST returned, then
1021                          * we may have performed an unsupported
1022                          * command.  The only thing this should be
1023                          * would be a ten byte read where only a six
1024                          * byte read was supported.  Also, on a system
1025                          * where READ CAPACITY failed, we may have
1026                          * read past the end of the disk.
1027                          */
1028                         if ((cmd->device->use_10_for_rw &&
1029                             sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
1030                             (cmd->cmnd[0] == READ_10 ||
1031                              cmd->cmnd[0] == WRITE_10)) {
1032                                 /* This will issue a new 6-byte command. */
1033                                 cmd->device->use_10_for_rw = 0;
1034                                 action = ACTION_REPREP;
1035                         } else if (sshdr.asc == 0x10) /* DIX */ {
1036                                 description = "Host Data Integrity Failure";
1037                                 action = ACTION_FAIL;
1038                                 error = -EILSEQ;
1039                         } else
1040                                 action = ACTION_FAIL;
1041                         break;
1042                 case ABORTED_COMMAND:
1043                         if (sshdr.asc == 0x10) { /* DIF */
1044                                 description = "Target Data Integrity Failure";
1045                                 action = ACTION_FAIL;
1046                                 error = -EILSEQ;
1047                         } else
1048                                 action = ACTION_RETRY;
1049                         break;
1050                 case NOT_READY:
1051                         /* If the device is in the process of becoming
1052                          * ready, or has a temporary blockage, retry.
1053                          */
1054                         if (sshdr.asc == 0x04) {
1055                                 switch (sshdr.ascq) {
1056                                 case 0x01: /* becoming ready */
1057                                 case 0x04: /* format in progress */
1058                                 case 0x05: /* rebuild in progress */
1059                                 case 0x06: /* recalculation in progress */
1060                                 case 0x07: /* operation in progress */
1061                                 case 0x08: /* Long write in progress */
1062                                 case 0x09: /* self test in progress */
1063                                         action = ACTION_DELAYED_RETRY;
1064                                         break;
1065                                 default:
1066                                         description = "Device not ready";
1067                                         action = ACTION_FAIL;
1068                                         break;
1069                                 }
1070                         } else {
1071                                 description = "Device not ready";
1072                                 action = ACTION_FAIL;
1073                         }
1074                         break;
1075                 case VOLUME_OVERFLOW:
1076                         /* See SSC3rXX or current. */
1077                         action = ACTION_FAIL;
1078                         break;
1079                 default:
1080                         description = "Unhandled sense code";
1081                         action = ACTION_FAIL;
1082                         break;
1083                 }
1084         } else {
1085                 description = "Unhandled error code";
1086                 action = ACTION_FAIL;
1087         }
1088
1089         switch (action) {
1090         case ACTION_FAIL:
1091                 /* Give up and fail the remainder of the request */
1092                 scsi_release_buffers(cmd);
1093                 if (!(req->cmd_flags & REQ_QUIET)) {
1094                         if (description)
1095                                 scmd_printk(KERN_INFO, cmd, "%s\n",
1096                                             description);
1097                         scsi_print_result(cmd);
1098                         if (driver_byte(result) & DRIVER_SENSE)
1099                                 scsi_print_sense("", cmd);
1100                 }
1101                 blk_end_request(req, -EIO, blk_rq_bytes(req));
1102                 scsi_next_command(cmd);
1103                 break;
1104         case ACTION_REPREP:
1105                 /* Unprep the request and put it back at the head of the queue.
1106                  * A new command will be prepared and issued.
1107                  */
1108                 scsi_release_buffers(cmd);
1109                 scsi_requeue_command(q, cmd);
1110                 break;
1111         case ACTION_RETRY:
1112                 /* Retry the same command immediately */
1113                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
1114                 break;
1115         case ACTION_DELAYED_RETRY:
1116                 /* Retry the same command after a delay */
1117                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
1118                 break;
1119         }
1120 }
1121
1122 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
1123                              gfp_t gfp_mask)
1124 {
1125         int count;
1126
1127         /*
1128          * If sg table allocation fails, requeue request later.
1129          */
1130         if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
1131                                         gfp_mask))) {
1132                 return BLKPREP_DEFER;
1133         }
1134
1135         req->buffer = NULL;
1136
1137         /* 
1138          * Next, walk the list, and fill in the addresses and sizes of
1139          * each segment.
1140          */
1141         count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1142         BUG_ON(count > sdb->table.nents);
1143         sdb->table.nents = count;
1144         if (blk_pc_request(req))
1145                 sdb->length = req->data_len;
1146         else
1147                 sdb->length = req->nr_sectors << 9;
1148         return BLKPREP_OK;
1149 }
1150
1151 /*
1152  * Function:    scsi_init_io()
1153  *
1154  * Purpose:     SCSI I/O initialize function.
1155  *
1156  * Arguments:   cmd   - Command descriptor we wish to initialize
1157  *
1158  * Returns:     0 on success
1159  *              BLKPREP_DEFER if the failure is retryable
1160  *              BLKPREP_KILL if the failure is fatal
1161  */
1162 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1163 {
1164         int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
1165         if (error)
1166                 goto err_exit;
1167
1168         if (blk_bidi_rq(cmd->request)) {
1169                 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1170                         scsi_sdb_cache, GFP_ATOMIC);
1171                 if (!bidi_sdb) {
1172                         error = BLKPREP_DEFER;
1173                         goto err_exit;
1174                 }
1175
1176                 cmd->request->next_rq->special = bidi_sdb;
1177                 error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
1178                                                                     GFP_ATOMIC);
1179                 if (error)
1180                         goto err_exit;
1181         }
1182
1183         if (blk_integrity_rq(cmd->request)) {
1184                 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1185                 int ivecs, count;
1186
1187                 BUG_ON(prot_sdb == NULL);
1188                 ivecs = blk_rq_count_integrity_sg(cmd->request);
1189
1190                 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1191                         error = BLKPREP_DEFER;
1192                         goto err_exit;
1193                 }
1194
1195                 count = blk_rq_map_integrity_sg(cmd->request,
1196                                                 prot_sdb->table.sgl);
1197                 BUG_ON(unlikely(count > ivecs));
1198
1199                 cmd->prot_sdb = prot_sdb;
1200                 cmd->prot_sdb->table.nents = count;
1201         }
1202
1203         return BLKPREP_OK ;
1204
1205 err_exit:
1206         scsi_release_buffers(cmd);
1207         if (error == BLKPREP_KILL)
1208                 scsi_put_command(cmd);
1209         else /* BLKPREP_DEFER */
1210                 scsi_unprep_request(cmd->request);
1211
1212         return error;
1213 }
1214 EXPORT_SYMBOL(scsi_init_io);
1215
1216 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1217                 struct request *req)
1218 {
1219         struct scsi_cmnd *cmd;
1220
1221         if (!req->special) {
1222                 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1223                 if (unlikely(!cmd))
1224                         return NULL;
1225                 req->special = cmd;
1226         } else {
1227                 cmd = req->special;
1228         }
1229
1230         /* pull a tag out of the request if we have one */
1231         cmd->tag = req->tag;
1232         cmd->request = req;
1233
1234         cmd->cmnd = req->cmd;
1235
1236         return cmd;
1237 }
1238
1239 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1240 {
1241         struct scsi_cmnd *cmd;
1242         int ret = scsi_prep_state_check(sdev, req);
1243
1244         if (ret != BLKPREP_OK)
1245                 return ret;
1246
1247         cmd = scsi_get_cmd_from_req(sdev, req);
1248         if (unlikely(!cmd))
1249                 return BLKPREP_DEFER;
1250
1251         /*
1252          * BLOCK_PC requests may transfer data, in which case they must
1253          * a bio attached to them.  Or they might contain a SCSI command
1254          * that does not transfer data, in which case they may optionally
1255          * submit a request without an attached bio.
1256          */
1257         if (req->bio) {
1258                 int ret;
1259
1260                 BUG_ON(!req->nr_phys_segments);
1261
1262                 ret = scsi_init_io(cmd, GFP_ATOMIC);
1263                 if (unlikely(ret))
1264                         return ret;
1265         } else {
1266                 BUG_ON(req->data_len);
1267                 BUG_ON(req->data);
1268
1269                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1270                 req->buffer = NULL;
1271         }
1272
1273         cmd->cmd_len = req->cmd_len;
1274         if (!req->data_len)
1275                 cmd->sc_data_direction = DMA_NONE;
1276         else if (rq_data_dir(req) == WRITE)
1277                 cmd->sc_data_direction = DMA_TO_DEVICE;
1278         else
1279                 cmd->sc_data_direction = DMA_FROM_DEVICE;
1280         
1281         cmd->transfersize = req->data_len;
1282         cmd->allowed = req->retries;
1283         return BLKPREP_OK;
1284 }
1285 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1286
1287 /*
1288  * Setup a REQ_TYPE_FS command.  These are simple read/write request
1289  * from filesystems that still need to be translated to SCSI CDBs from
1290  * the ULD.
1291  */
1292 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1293 {
1294         struct scsi_cmnd *cmd;
1295         int ret = scsi_prep_state_check(sdev, req);
1296
1297         if (ret != BLKPREP_OK)
1298                 return ret;
1299
1300         if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1301                          && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1302                 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1303                 if (ret != BLKPREP_OK)
1304                         return ret;
1305         }
1306
1307         /*
1308          * Filesystem requests must transfer data.
1309          */
1310         BUG_ON(!req->nr_phys_segments);
1311
1312         cmd = scsi_get_cmd_from_req(sdev, req);
1313         if (unlikely(!cmd))
1314                 return BLKPREP_DEFER;
1315
1316         memset(cmd->cmnd, 0, BLK_MAX_CDB);
1317         return scsi_init_io(cmd, GFP_ATOMIC);
1318 }
1319 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1320
1321 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1322 {
1323         int ret = BLKPREP_OK;
1324
1325         /*
1326          * If the device is not in running state we will reject some
1327          * or all commands.
1328          */
1329         if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1330                 switch (sdev->sdev_state) {
1331                 case SDEV_OFFLINE:
1332                         /*
1333                          * If the device is offline we refuse to process any
1334                          * commands.  The device must be brought online
1335                          * before trying any recovery commands.
1336                          */
1337                         sdev_printk(KERN_ERR, sdev,
1338                                     "rejecting I/O to offline device\n");
1339                         ret = BLKPREP_KILL;
1340                         break;
1341                 case SDEV_DEL:
1342                         /*
1343                          * If the device is fully deleted, we refuse to
1344                          * process any commands as well.
1345                          */
1346                         sdev_printk(KERN_ERR, sdev,
1347                                     "rejecting I/O to dead device\n");
1348                         ret = BLKPREP_KILL;
1349                         break;
1350                 case SDEV_QUIESCE:
1351                 case SDEV_BLOCK:
1352                 case SDEV_CREATED_BLOCK:
1353                         /*
1354                          * If the devices is blocked we defer normal commands.
1355                          */
1356                         if (!(req->cmd_flags & REQ_PREEMPT))
1357                                 ret = BLKPREP_DEFER;
1358                         break;
1359                 default:
1360                         /*
1361                          * For any other not fully online state we only allow
1362                          * special commands.  In particular any user initiated
1363                          * command is not allowed.
1364                          */
1365                         if (!(req->cmd_flags & REQ_PREEMPT))
1366                                 ret = BLKPREP_KILL;
1367                         break;
1368                 }
1369         }
1370         return ret;
1371 }
1372 EXPORT_SYMBOL(scsi_prep_state_check);
1373
1374 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1375 {
1376         struct scsi_device *sdev = q->queuedata;
1377
1378         switch (ret) {
1379         case BLKPREP_KILL:
1380                 req->errors = DID_NO_CONNECT << 16;
1381                 /* release the command and kill it */
1382                 if (req->special) {
1383                         struct scsi_cmnd *cmd = req->special;
1384                         scsi_release_buffers(cmd);
1385                         scsi_put_command(cmd);
1386                         req->special = NULL;
1387                 }
1388                 break;
1389         case BLKPREP_DEFER:
1390                 /*
1391                  * If we defer, the elv_next_request() returns NULL, but the
1392                  * queue must be restarted, so we plug here if no returning
1393                  * command will automatically do that.
1394                  */
1395                 if (sdev->device_busy == 0)
1396                         blk_plug_device(q);
1397                 break;
1398         default:
1399                 req->cmd_flags |= REQ_DONTPREP;
1400         }
1401
1402         return ret;
1403 }
1404 EXPORT_SYMBOL(scsi_prep_return);
1405
1406 int scsi_prep_fn(struct request_queue *q, struct request *req)
1407 {
1408         struct scsi_device *sdev = q->queuedata;
1409         int ret = BLKPREP_KILL;
1410
1411         if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1412                 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1413         return scsi_prep_return(q, req, ret);
1414 }
1415
1416 /*
1417  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1418  * return 0.
1419  *
1420  * Called with the queue_lock held.
1421  */
1422 static inline int scsi_dev_queue_ready(struct request_queue *q,
1423                                   struct scsi_device *sdev)
1424 {
1425         if (sdev->device_busy == 0 && sdev->device_blocked) {
1426                 /*
1427                  * unblock after device_blocked iterates to zero
1428                  */
1429                 if (--sdev->device_blocked == 0) {
1430                         SCSI_LOG_MLQUEUE(3,
1431                                    sdev_printk(KERN_INFO, sdev,
1432                                    "unblocking device at zero depth\n"));
1433                 } else {
1434                         blk_plug_device(q);
1435                         return 0;
1436                 }
1437         }
1438         if (scsi_device_is_busy(sdev))
1439                 return 0;
1440
1441         return 1;
1442 }
1443
1444
1445 /*
1446  * scsi_target_queue_ready: checks if there we can send commands to target
1447  * @sdev: scsi device on starget to check.
1448  *
1449  * Called with the host lock held.
1450  */
1451 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1452                                            struct scsi_device *sdev)
1453 {
1454         struct scsi_target *starget = scsi_target(sdev);
1455
1456         if (starget->single_lun) {
1457                 if (starget->starget_sdev_user &&
1458                     starget->starget_sdev_user != sdev)
1459                         return 0;
1460                 starget->starget_sdev_user = sdev;
1461         }
1462
1463         if (starget->target_busy == 0 && starget->target_blocked) {
1464                 /*
1465                  * unblock after target_blocked iterates to zero
1466                  */
1467                 if (--starget->target_blocked == 0) {
1468                         SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1469                                          "unblocking target at zero depth\n"));
1470                 } else {
1471                         blk_plug_device(sdev->request_queue);
1472                         return 0;
1473                 }
1474         }
1475
1476         if (scsi_target_is_busy(starget)) {
1477                 if (list_empty(&sdev->starved_entry)) {
1478                         list_add_tail(&sdev->starved_entry,
1479                                       &shost->starved_list);
1480                         return 0;
1481                 }
1482         }
1483
1484         /* We're OK to process the command, so we can't be starved */
1485         if (!list_empty(&sdev->starved_entry))
1486                 list_del_init(&sdev->starved_entry);
1487         return 1;
1488 }
1489
1490 /*
1491  * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1492  * return 0. We must end up running the queue again whenever 0 is
1493  * returned, else IO can hang.
1494  *
1495  * Called with host_lock held.
1496  */
1497 static inline int scsi_host_queue_ready(struct request_queue *q,
1498                                    struct Scsi_Host *shost,
1499                                    struct scsi_device *sdev)
1500 {
1501         if (scsi_host_in_recovery(shost))
1502                 return 0;
1503         if (shost->host_busy == 0 && shost->host_blocked) {
1504                 /*
1505                  * unblock after host_blocked iterates to zero
1506                  */
1507                 if (--shost->host_blocked == 0) {
1508                         SCSI_LOG_MLQUEUE(3,
1509                                 printk("scsi%d unblocking host at zero depth\n",
1510                                         shost->host_no));
1511                 } else {
1512                         return 0;
1513                 }
1514         }
1515         if (scsi_host_is_busy(shost)) {
1516                 if (list_empty(&sdev->starved_entry))
1517                         list_add_tail(&sdev->starved_entry, &shost->starved_list);
1518                 return 0;
1519         }
1520
1521         /* We're OK to process the command, so we can't be starved */
1522         if (!list_empty(&sdev->starved_entry))
1523                 list_del_init(&sdev->starved_entry);
1524
1525         return 1;
1526 }
1527
1528 /*
1529  * Busy state exporting function for request stacking drivers.
1530  *
1531  * For efficiency, no lock is taken to check the busy state of
1532  * shost/starget/sdev, since the returned value is not guaranteed and
1533  * may be changed after request stacking drivers call the function,
1534  * regardless of taking lock or not.
1535  *
1536  * When scsi can't dispatch I/Os anymore and needs to kill I/Os
1537  * (e.g. !sdev), scsi needs to return 'not busy'.
1538  * Otherwise, request stacking drivers may hold requests forever.
1539  */
1540 static int scsi_lld_busy(struct request_queue *q)
1541 {
1542         struct scsi_device *sdev = q->queuedata;
1543         struct Scsi_Host *shost;
1544         struct scsi_target *starget;
1545
1546         if (!sdev)
1547                 return 0;
1548
1549         shost = sdev->host;
1550         starget = scsi_target(sdev);
1551
1552         if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
1553             scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
1554                 return 1;
1555
1556         return 0;
1557 }
1558
1559 /*
1560  * Kill a request for a dead device
1561  */
1562 static void scsi_kill_request(struct request *req, struct request_queue *q)
1563 {
1564         struct scsi_cmnd *cmd = req->special;
1565         struct scsi_device *sdev = cmd->device;
1566         struct scsi_target *starget = scsi_target(sdev);
1567         struct Scsi_Host *shost = sdev->host;
1568
1569         blkdev_dequeue_request(req);
1570
1571         if (unlikely(cmd == NULL)) {
1572                 printk(KERN_CRIT "impossible request in %s.\n",
1573                                  __func__);
1574                 BUG();
1575         }
1576
1577         scsi_init_cmd_errh(cmd);
1578         cmd->result = DID_NO_CONNECT << 16;
1579         atomic_inc(&cmd->device->iorequest_cnt);
1580
1581         /*
1582          * SCSI request completion path will do scsi_device_unbusy(),
1583          * bump busy counts.  To bump the counters, we need to dance
1584          * with the locks as normal issue path does.
1585          */
1586         sdev->device_busy++;
1587         spin_unlock(sdev->request_queue->queue_lock);
1588         spin_lock(shost->host_lock);
1589         shost->host_busy++;
1590         starget->target_busy++;
1591         spin_unlock(shost->host_lock);
1592         spin_lock(sdev->request_queue->queue_lock);
1593
1594         blk_complete_request(req);
1595 }
1596
1597 static void scsi_softirq_done(struct request *rq)
1598 {
1599         struct scsi_cmnd *cmd = rq->special;
1600         unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1601         int disposition;
1602
1603         INIT_LIST_HEAD(&cmd->eh_entry);
1604
1605         /*
1606          * Set the serial numbers back to zero
1607          */
1608         cmd->serial_number = 0;
1609
1610         atomic_inc(&cmd->device->iodone_cnt);
1611         if (cmd->result)
1612                 atomic_inc(&cmd->device->ioerr_cnt);
1613
1614         disposition = scsi_decide_disposition(cmd);
1615         if (disposition != SUCCESS &&
1616             time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1617                 sdev_printk(KERN_ERR, cmd->device,
1618                             "timing out command, waited %lus\n",
1619                             wait_for/HZ);
1620                 disposition = SUCCESS;
1621         }
1622                         
1623         scsi_log_completion(cmd, disposition);
1624
1625         switch (disposition) {
1626                 case SUCCESS:
1627                         scsi_finish_command(cmd);
1628                         break;
1629                 case NEEDS_RETRY:
1630                         scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1631                         break;
1632                 case ADD_TO_MLQUEUE:
1633                         scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1634                         break;
1635                 default:
1636                         if (!scsi_eh_scmd_add(cmd, 0))
1637                                 scsi_finish_command(cmd);
1638         }
1639 }
1640
1641 /*
1642  * Function:    scsi_request_fn()
1643  *
1644  * Purpose:     Main strategy routine for SCSI.
1645  *
1646  * Arguments:   q       - Pointer to actual queue.
1647  *
1648  * Returns:     Nothing
1649  *
1650  * Lock status: IO request lock assumed to be held when called.
1651  */
1652 static void scsi_request_fn(struct request_queue *q)
1653 {
1654         struct scsi_device *sdev = q->queuedata;
1655         struct Scsi_Host *shost;
1656         struct scsi_cmnd *cmd;
1657         struct request *req;
1658
1659         if (!sdev) {
1660                 printk("scsi: killing requests for dead queue\n");
1661                 while ((req = elv_next_request(q)) != NULL)
1662                         scsi_kill_request(req, q);
1663                 return;
1664         }
1665
1666         if(!get_device(&sdev->sdev_gendev))
1667                 /* We must be tearing the block queue down already */
1668                 return;
1669
1670         /*
1671          * To start with, we keep looping until the queue is empty, or until
1672          * the host is no longer able to accept any more requests.
1673          */
1674         shost = sdev->host;
1675         while (!blk_queue_plugged(q)) {
1676                 int rtn;
1677                 /*
1678                  * get next queueable request.  We do this early to make sure
1679                  * that the request is fully prepared even if we cannot 
1680                  * accept it.
1681                  */
1682                 req = elv_next_request(q);
1683                 if (!req || !scsi_dev_queue_ready(q, sdev))
1684                         break;
1685
1686                 if (unlikely(!scsi_device_online(sdev))) {
1687                         sdev_printk(KERN_ERR, sdev,
1688                                     "rejecting I/O to offline device\n");
1689                         scsi_kill_request(req, q);
1690                         continue;
1691                 }
1692
1693
1694                 /*
1695                  * Remove the request from the request list.
1696                  */
1697                 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1698                         blkdev_dequeue_request(req);
1699                 sdev->device_busy++;
1700
1701                 spin_unlock(q->queue_lock);
1702                 cmd = req->special;
1703                 if (unlikely(cmd == NULL)) {
1704                         printk(KERN_CRIT "impossible request in %s.\n"
1705                                          "please mail a stack trace to "
1706                                          "linux-scsi@vger.kernel.org\n",
1707                                          __func__);
1708                         blk_dump_rq_flags(req, "foo");
1709                         BUG();
1710                 }
1711                 spin_lock(shost->host_lock);
1712
1713                 /*
1714                  * We hit this when the driver is using a host wide
1715                  * tag map. For device level tag maps the queue_depth check
1716                  * in the device ready fn would prevent us from trying
1717                  * to allocate a tag. Since the map is a shared host resource
1718                  * we add the dev to the starved list so it eventually gets
1719                  * a run when a tag is freed.
1720                  */
1721                 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1722                         if (list_empty(&sdev->starved_entry))
1723                                 list_add_tail(&sdev->starved_entry,
1724                                               &shost->starved_list);
1725                         goto not_ready;
1726                 }
1727
1728                 if (!scsi_target_queue_ready(shost, sdev))
1729                         goto not_ready;
1730
1731                 if (!scsi_host_queue_ready(q, shost, sdev))
1732                         goto not_ready;
1733
1734                 scsi_target(sdev)->target_busy++;
1735                 shost->host_busy++;
1736
1737                 /*
1738                  * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1739                  *              take the lock again.
1740                  */
1741                 spin_unlock_irq(shost->host_lock);
1742
1743                 /*
1744                  * Finally, initialize any error handling parameters, and set up
1745                  * the timers for timeouts.
1746                  */
1747                 scsi_init_cmd_errh(cmd);
1748
1749                 /*
1750                  * Dispatch the command to the low-level driver.
1751                  */
1752                 rtn = scsi_dispatch_cmd(cmd);
1753                 spin_lock_irq(q->queue_lock);
1754                 if(rtn) {
1755                         /* we're refusing the command; because of
1756                          * the way locks get dropped, we need to 
1757                          * check here if plugging is required */
1758                         if(sdev->device_busy == 0)
1759                                 blk_plug_device(q);
1760
1761                         break;
1762                 }
1763         }
1764
1765         goto out;
1766
1767  not_ready:
1768         spin_unlock_irq(shost->host_lock);
1769
1770         /*
1771          * lock q, handle tag, requeue req, and decrement device_busy. We
1772          * must return with queue_lock held.
1773          *
1774          * Decrementing device_busy without checking it is OK, as all such
1775          * cases (host limits or settings) should run the queue at some
1776          * later time.
1777          */
1778         spin_lock_irq(q->queue_lock);
1779         blk_requeue_request(q, req);
1780         sdev->device_busy--;
1781         if(sdev->device_busy == 0)
1782                 blk_plug_device(q);
1783  out:
1784         /* must be careful here...if we trigger the ->remove() function
1785          * we cannot be holding the q lock */
1786         spin_unlock_irq(q->queue_lock);
1787         put_device(&sdev->sdev_gendev);
1788         spin_lock_irq(q->queue_lock);
1789 }
1790
1791 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1792 {
1793         struct device *host_dev;
1794         u64 bounce_limit = 0xffffffff;
1795
1796         if (shost->unchecked_isa_dma)
1797                 return BLK_BOUNCE_ISA;
1798         /*
1799          * Platforms with virtual-DMA translation
1800          * hardware have no practical limit.
1801          */
1802         if (!PCI_DMA_BUS_IS_PHYS)
1803                 return BLK_BOUNCE_ANY;
1804
1805         host_dev = scsi_get_device(shost);
1806         if (host_dev && host_dev->dma_mask)
1807                 bounce_limit = *host_dev->dma_mask;
1808
1809         return bounce_limit;
1810 }
1811 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1812
1813 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1814                                          request_fn_proc *request_fn)
1815 {
1816         struct request_queue *q;
1817         struct device *dev = shost->shost_gendev.parent;
1818
1819         q = blk_init_queue(request_fn, NULL);
1820         if (!q)
1821                 return NULL;
1822
1823         /*
1824          * this limit is imposed by hardware restrictions
1825          */
1826         blk_queue_max_hw_segments(q, shost->sg_tablesize);
1827         blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1828
1829         blk_queue_max_sectors(q, shost->max_sectors);
1830         blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1831         blk_queue_segment_boundary(q, shost->dma_boundary);
1832         dma_set_seg_boundary(dev, shost->dma_boundary);
1833
1834         blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1835
1836         /* New queue, no concurrency on queue_flags */
1837         if (!shost->use_clustering)
1838                 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
1839
1840         /*
1841          * set a reasonable default alignment on word boundaries: the
1842          * host and device may alter it using
1843          * blk_queue_update_dma_alignment() later.
1844          */
1845         blk_queue_dma_alignment(q, 0x03);
1846
1847         return q;
1848 }
1849 EXPORT_SYMBOL(__scsi_alloc_queue);
1850
1851 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1852 {
1853         struct request_queue *q;
1854
1855         q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1856         if (!q)
1857                 return NULL;
1858
1859         blk_queue_prep_rq(q, scsi_prep_fn);
1860         blk_queue_softirq_done(q, scsi_softirq_done);
1861         blk_queue_rq_timed_out(q, scsi_times_out);
1862         blk_queue_lld_busy(q, scsi_lld_busy);
1863         return q;
1864 }
1865
1866 void scsi_free_queue(struct request_queue *q)
1867 {
1868         blk_cleanup_queue(q);
1869 }
1870
1871 /*
1872  * Function:    scsi_block_requests()
1873  *
1874  * Purpose:     Utility function used by low-level drivers to prevent further
1875  *              commands from being queued to the device.
1876  *
1877  * Arguments:   shost       - Host in question
1878  *
1879  * Returns:     Nothing
1880  *
1881  * Lock status: No locks are assumed held.
1882  *
1883  * Notes:       There is no timer nor any other means by which the requests
1884  *              get unblocked other than the low-level driver calling
1885  *              scsi_unblock_requests().
1886  */
1887 void scsi_block_requests(struct Scsi_Host *shost)
1888 {
1889         shost->host_self_blocked = 1;
1890 }
1891 EXPORT_SYMBOL(scsi_block_requests);
1892
1893 /*
1894  * Function:    scsi_unblock_requests()
1895  *
1896  * Purpose:     Utility function used by low-level drivers to allow further
1897  *              commands from being queued to the device.
1898  *
1899  * Arguments:   shost       - Host in question
1900  *
1901  * Returns:     Nothing
1902  *
1903  * Lock status: No locks are assumed held.
1904  *
1905  * Notes:       There is no timer nor any other means by which the requests
1906  *              get unblocked other than the low-level driver calling
1907  *              scsi_unblock_requests().
1908  *
1909  *              This is done as an API function so that changes to the
1910  *              internals of the scsi mid-layer won't require wholesale
1911  *              changes to drivers that use this feature.
1912  */
1913 void scsi_unblock_requests(struct Scsi_Host *shost)
1914 {
1915         shost->host_self_blocked = 0;
1916         scsi_run_host_queues(shost);
1917 }
1918 EXPORT_SYMBOL(scsi_unblock_requests);
1919
1920 int __init scsi_init_queue(void)
1921 {
1922         int i;
1923
1924         scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1925                                         sizeof(struct scsi_io_context),
1926                                         0, 0, NULL);
1927         if (!scsi_io_context_cache) {
1928                 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1929                 return -ENOMEM;
1930         }
1931
1932         scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1933                                            sizeof(struct scsi_data_buffer),
1934                                            0, 0, NULL);
1935         if (!scsi_sdb_cache) {
1936                 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1937                 goto cleanup_io_context;
1938         }
1939
1940         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1941                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1942                 int size = sgp->size * sizeof(struct scatterlist);
1943
1944                 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1945                                 SLAB_HWCACHE_ALIGN, NULL);
1946                 if (!sgp->slab) {
1947                         printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1948                                         sgp->name);
1949                         goto cleanup_sdb;
1950                 }
1951
1952                 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1953                                                      sgp->slab);
1954                 if (!sgp->pool) {
1955                         printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1956                                         sgp->name);
1957                         goto cleanup_sdb;
1958                 }
1959         }
1960
1961         return 0;
1962
1963 cleanup_sdb:
1964         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1965                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1966                 if (sgp->pool)
1967                         mempool_destroy(sgp->pool);
1968                 if (sgp->slab)
1969                         kmem_cache_destroy(sgp->slab);
1970         }
1971         kmem_cache_destroy(scsi_sdb_cache);
1972 cleanup_io_context:
1973         kmem_cache_destroy(scsi_io_context_cache);
1974
1975         return -ENOMEM;
1976 }
1977
1978 void scsi_exit_queue(void)
1979 {
1980         int i;
1981
1982         kmem_cache_destroy(scsi_io_context_cache);
1983         kmem_cache_destroy(scsi_sdb_cache);
1984
1985         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1986                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1987                 mempool_destroy(sgp->pool);
1988                 kmem_cache_destroy(sgp->slab);
1989         }
1990 }
1991
1992 /**
1993  *      scsi_mode_select - issue a mode select
1994  *      @sdev:  SCSI device to be queried
1995  *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
1996  *      @sp:    Save page bit (0 == don't save, 1 == save)
1997  *      @modepage: mode page being requested
1998  *      @buffer: request buffer (may not be smaller than eight bytes)
1999  *      @len:   length of request buffer.
2000  *      @timeout: command timeout
2001  *      @retries: number of retries before failing
2002  *      @data: returns a structure abstracting the mode header data
2003  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2004  *              must be SCSI_SENSE_BUFFERSIZE big.
2005  *
2006  *      Returns zero if successful; negative error number or scsi
2007  *      status on error
2008  *
2009  */
2010 int
2011 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
2012                  unsigned char *buffer, int len, int timeout, int retries,
2013                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2014 {
2015         unsigned char cmd[10];
2016         unsigned char *real_buffer;
2017         int ret;
2018
2019         memset(cmd, 0, sizeof(cmd));
2020         cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
2021
2022         if (sdev->use_10_for_ms) {
2023                 if (len > 65535)
2024                         return -EINVAL;
2025                 real_buffer = kmalloc(8 + len, GFP_KERNEL);
2026                 if (!real_buffer)
2027                         return -ENOMEM;
2028                 memcpy(real_buffer + 8, buffer, len);
2029                 len += 8;
2030                 real_buffer[0] = 0;
2031                 real_buffer[1] = 0;
2032                 real_buffer[2] = data->medium_type;
2033                 real_buffer[3] = data->device_specific;
2034                 real_buffer[4] = data->longlba ? 0x01 : 0;
2035                 real_buffer[5] = 0;
2036                 real_buffer[6] = data->block_descriptor_length >> 8;
2037                 real_buffer[7] = data->block_descriptor_length;
2038
2039                 cmd[0] = MODE_SELECT_10;
2040                 cmd[7] = len >> 8;
2041                 cmd[8] = len;
2042         } else {
2043                 if (len > 255 || data->block_descriptor_length > 255 ||
2044                     data->longlba)
2045                         return -EINVAL;
2046
2047                 real_buffer = kmalloc(4 + len, GFP_KERNEL);
2048                 if (!real_buffer)
2049                         return -ENOMEM;
2050                 memcpy(real_buffer + 4, buffer, len);
2051                 len += 4;
2052                 real_buffer[0] = 0;
2053                 real_buffer[1] = data->medium_type;
2054                 real_buffer[2] = data->device_specific;
2055                 real_buffer[3] = data->block_descriptor_length;
2056                 
2057
2058                 cmd[0] = MODE_SELECT;
2059                 cmd[4] = len;
2060         }
2061
2062         ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2063                                sshdr, timeout, retries, NULL);
2064         kfree(real_buffer);
2065         return ret;
2066 }
2067 EXPORT_SYMBOL_GPL(scsi_mode_select);
2068
2069 /**
2070  *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2071  *      @sdev:  SCSI device to be queried
2072  *      @dbd:   set if mode sense will allow block descriptors to be returned
2073  *      @modepage: mode page being requested
2074  *      @buffer: request buffer (may not be smaller than eight bytes)
2075  *      @len:   length of request buffer.
2076  *      @timeout: command timeout
2077  *      @retries: number of retries before failing
2078  *      @data: returns a structure abstracting the mode header data
2079  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2080  *              must be SCSI_SENSE_BUFFERSIZE big.
2081  *
2082  *      Returns zero if unsuccessful, or the header offset (either 4
2083  *      or 8 depending on whether a six or ten byte command was
2084  *      issued) if successful.
2085  */
2086 int
2087 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2088                   unsigned char *buffer, int len, int timeout, int retries,
2089                   struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2090 {
2091         unsigned char cmd[12];
2092         int use_10_for_ms;
2093         int header_length;
2094         int result;
2095         struct scsi_sense_hdr my_sshdr;
2096
2097         memset(data, 0, sizeof(*data));
2098         memset(&cmd[0], 0, 12);
2099         cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
2100         cmd[2] = modepage;
2101
2102         /* caller might not be interested in sense, but we need it */
2103         if (!sshdr)
2104                 sshdr = &my_sshdr;
2105
2106  retry:
2107         use_10_for_ms = sdev->use_10_for_ms;
2108
2109         if (use_10_for_ms) {
2110                 if (len < 8)
2111                         len = 8;
2112
2113                 cmd[0] = MODE_SENSE_10;
2114                 cmd[8] = len;
2115                 header_length = 8;
2116         } else {
2117                 if (len < 4)
2118                         len = 4;
2119
2120                 cmd[0] = MODE_SENSE;
2121                 cmd[4] = len;
2122                 header_length = 4;
2123         }
2124
2125         memset(buffer, 0, len);
2126
2127         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2128                                   sshdr, timeout, retries, NULL);
2129
2130         /* This code looks awful: what it's doing is making sure an
2131          * ILLEGAL REQUEST sense return identifies the actual command
2132          * byte as the problem.  MODE_SENSE commands can return
2133          * ILLEGAL REQUEST if the code page isn't supported */
2134
2135         if (use_10_for_ms && !scsi_status_is_good(result) &&
2136             (driver_byte(result) & DRIVER_SENSE)) {
2137                 if (scsi_sense_valid(sshdr)) {
2138                         if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2139                             (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2140                                 /* 
2141                                  * Invalid command operation code
2142                                  */
2143                                 sdev->use_10_for_ms = 0;
2144                                 goto retry;
2145                         }
2146                 }
2147         }
2148
2149         if(scsi_status_is_good(result)) {
2150                 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2151                              (modepage == 6 || modepage == 8))) {
2152                         /* Initio breakage? */
2153                         header_length = 0;
2154                         data->length = 13;
2155                         data->medium_type = 0;
2156                         data->device_specific = 0;
2157                         data->longlba = 0;
2158                         data->block_descriptor_length = 0;
2159                 } else if(use_10_for_ms) {
2160                         data->length = buffer[0]*256 + buffer[1] + 2;
2161                         data->medium_type = buffer[2];
2162                         data->device_specific = buffer[3];
2163                         data->longlba = buffer[4] & 0x01;
2164                         data->block_descriptor_length = buffer[6]*256
2165                                 + buffer[7];
2166                 } else {
2167                         data->length = buffer[0] + 1;
2168                         data->medium_type = buffer[1];
2169                         data->device_specific = buffer[2];
2170                         data->block_descriptor_length = buffer[3];
2171                 }
2172                 data->header_length = header_length;
2173         }
2174
2175         return result;
2176 }
2177 EXPORT_SYMBOL(scsi_mode_sense);
2178
2179 /**
2180  *      scsi_test_unit_ready - test if unit is ready
2181  *      @sdev:  scsi device to change the state of.
2182  *      @timeout: command timeout
2183  *      @retries: number of retries before failing
2184  *      @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2185  *              returning sense. Make sure that this is cleared before passing
2186  *              in.
2187  *
2188  *      Returns zero if unsuccessful or an error if TUR failed.  For
2189  *      removable media, a return of NOT_READY or UNIT_ATTENTION is
2190  *      translated to success, with the ->changed flag updated.
2191  **/
2192 int
2193 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2194                      struct scsi_sense_hdr *sshdr_external)
2195 {
2196         char cmd[] = {
2197                 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2198         };
2199         struct scsi_sense_hdr *sshdr;
2200         int result;
2201
2202         if (!sshdr_external)
2203                 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2204         else
2205                 sshdr = sshdr_external;
2206
2207         /* try to eat the UNIT_ATTENTION if there are enough retries */
2208         do {
2209                 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2210                                           timeout, retries, NULL);
2211                 if (sdev->removable && scsi_sense_valid(sshdr) &&
2212                     sshdr->sense_key == UNIT_ATTENTION)
2213                         sdev->changed = 1;
2214         } while (scsi_sense_valid(sshdr) &&
2215                  sshdr->sense_key == UNIT_ATTENTION && --retries);
2216
2217         if (!sshdr)
2218                 /* could not allocate sense buffer, so can't process it */
2219                 return result;
2220
2221         if (sdev->removable && scsi_sense_valid(sshdr) &&
2222             (sshdr->sense_key == UNIT_ATTENTION ||
2223              sshdr->sense_key == NOT_READY)) {
2224                 sdev->changed = 1;
2225                 result = 0;
2226         }
2227         if (!sshdr_external)
2228                 kfree(sshdr);
2229         return result;
2230 }
2231 EXPORT_SYMBOL(scsi_test_unit_ready);
2232
2233 /**
2234  *      scsi_device_set_state - Take the given device through the device state model.
2235  *      @sdev:  scsi device to change the state of.
2236  *      @state: state to change to.
2237  *
2238  *      Returns zero if unsuccessful or an error if the requested 
2239  *      transition is illegal.
2240  */
2241 int
2242 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2243 {
2244         enum scsi_device_state oldstate = sdev->sdev_state;
2245
2246         if (state == oldstate)
2247                 return 0;
2248
2249         switch (state) {
2250         case SDEV_CREATED:
2251                 switch (oldstate) {
2252                 case SDEV_CREATED_BLOCK:
2253                         break;
2254                 default:
2255                         goto illegal;
2256                 }
2257                 break;
2258                         
2259         case SDEV_RUNNING:
2260                 switch (oldstate) {
2261                 case SDEV_CREATED:
2262                 case SDEV_OFFLINE:
2263                 case SDEV_QUIESCE:
2264                 case SDEV_BLOCK:
2265                         break;
2266                 default:
2267                         goto illegal;
2268                 }
2269                 break;
2270
2271         case SDEV_QUIESCE:
2272                 switch (oldstate) {
2273                 case SDEV_RUNNING:
2274                 case SDEV_OFFLINE:
2275                         break;
2276                 default:
2277                         goto illegal;
2278                 }
2279                 break;
2280
2281         case SDEV_OFFLINE:
2282                 switch (oldstate) {
2283                 case SDEV_CREATED:
2284                 case SDEV_RUNNING:
2285                 case SDEV_QUIESCE:
2286                 case SDEV_BLOCK:
2287                         break;
2288                 default:
2289                         goto illegal;
2290                 }
2291                 break;
2292
2293         case SDEV_BLOCK:
2294                 switch (oldstate) {
2295                 case SDEV_RUNNING:
2296                 case SDEV_CREATED_BLOCK:
2297                         break;
2298                 default:
2299                         goto illegal;
2300                 }
2301                 break;
2302
2303         case SDEV_CREATED_BLOCK:
2304                 switch (oldstate) {
2305                 case SDEV_CREATED:
2306                         break;
2307                 default:
2308                         goto illegal;
2309                 }
2310                 break;
2311
2312         case SDEV_CANCEL:
2313                 switch (oldstate) {
2314                 case SDEV_CREATED:
2315                 case SDEV_RUNNING:
2316                 case SDEV_QUIESCE:
2317                 case SDEV_OFFLINE:
2318                 case SDEV_BLOCK:
2319                         break;
2320                 default:
2321                         goto illegal;
2322                 }
2323                 break;
2324
2325         case SDEV_DEL:
2326                 switch (oldstate) {
2327                 case SDEV_CREATED:
2328                 case SDEV_RUNNING:
2329                 case SDEV_OFFLINE:
2330                 case SDEV_CANCEL:
2331                         break;
2332                 default:
2333                         goto illegal;
2334                 }
2335                 break;
2336
2337         }
2338         sdev->sdev_state = state;
2339         return 0;
2340
2341  illegal:
2342         SCSI_LOG_ERROR_RECOVERY(1, 
2343                                 sdev_printk(KERN_ERR, sdev,
2344                                             "Illegal state transition %s->%s\n",
2345                                             scsi_device_state_name(oldstate),
2346                                             scsi_device_state_name(state))
2347                                 );
2348         return -EINVAL;
2349 }
2350 EXPORT_SYMBOL(scsi_device_set_state);
2351
2352 /**
2353  *      sdev_evt_emit - emit a single SCSI device uevent
2354  *      @sdev: associated SCSI device
2355  *      @evt: event to emit
2356  *
2357  *      Send a single uevent (scsi_event) to the associated scsi_device.
2358  */
2359 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2360 {
2361         int idx = 0;
2362         char *envp[3];
2363
2364         switch (evt->evt_type) {
2365         case SDEV_EVT_MEDIA_CHANGE:
2366                 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2367                 break;
2368
2369         default:
2370                 /* do nothing */
2371                 break;
2372         }
2373
2374         envp[idx++] = NULL;
2375
2376         kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2377 }
2378
2379 /**
2380  *      sdev_evt_thread - send a uevent for each scsi event
2381  *      @work: work struct for scsi_device
2382  *
2383  *      Dispatch queued events to their associated scsi_device kobjects
2384  *      as uevents.
2385  */
2386 void scsi_evt_thread(struct work_struct *work)
2387 {
2388         struct scsi_device *sdev;
2389         LIST_HEAD(event_list);
2390
2391         sdev = container_of(work, struct scsi_device, event_work);
2392
2393         while (1) {
2394                 struct scsi_event *evt;
2395                 struct list_head *this, *tmp;
2396                 unsigned long flags;
2397
2398                 spin_lock_irqsave(&sdev->list_lock, flags);
2399                 list_splice_init(&sdev->event_list, &event_list);
2400                 spin_unlock_irqrestore(&sdev->list_lock, flags);
2401
2402                 if (list_empty(&event_list))
2403                         break;
2404
2405                 list_for_each_safe(this, tmp, &event_list) {
2406                         evt = list_entry(this, struct scsi_event, node);
2407                         list_del(&evt->node);
2408                         scsi_evt_emit(sdev, evt);
2409                         kfree(evt);
2410                 }
2411         }
2412 }
2413
2414 /**
2415  *      sdev_evt_send - send asserted event to uevent thread
2416  *      @sdev: scsi_device event occurred on
2417  *      @evt: event to send
2418  *
2419  *      Assert scsi device event asynchronously.
2420  */
2421 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2422 {
2423         unsigned long flags;
2424
2425 #if 0
2426         /* FIXME: currently this check eliminates all media change events
2427          * for polled devices.  Need to update to discriminate between AN
2428          * and polled events */
2429         if (!test_bit(evt->evt_type, sdev->supported_events)) {
2430                 kfree(evt);
2431                 return;
2432         }
2433 #endif
2434
2435         spin_lock_irqsave(&sdev->list_lock, flags);
2436         list_add_tail(&evt->node, &sdev->event_list);
2437         schedule_work(&sdev->event_work);
2438         spin_unlock_irqrestore(&sdev->list_lock, flags);
2439 }
2440 EXPORT_SYMBOL_GPL(sdev_evt_send);
2441
2442 /**
2443  *      sdev_evt_alloc - allocate a new scsi event
2444  *      @evt_type: type of event to allocate
2445  *      @gfpflags: GFP flags for allocation
2446  *
2447  *      Allocates and returns a new scsi_event.
2448  */
2449 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2450                                   gfp_t gfpflags)
2451 {
2452         struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2453         if (!evt)
2454                 return NULL;
2455
2456         evt->evt_type = evt_type;
2457         INIT_LIST_HEAD(&evt->node);
2458
2459         /* evt_type-specific initialization, if any */
2460         switch (evt_type) {
2461         case SDEV_EVT_MEDIA_CHANGE:
2462         default:
2463                 /* do nothing */
2464                 break;
2465         }
2466
2467         return evt;
2468 }
2469 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2470
2471 /**
2472  *      sdev_evt_send_simple - send asserted event to uevent thread
2473  *      @sdev: scsi_device event occurred on
2474  *      @evt_type: type of event to send
2475  *      @gfpflags: GFP flags for allocation
2476  *
2477  *      Assert scsi device event asynchronously, given an event type.
2478  */
2479 void sdev_evt_send_simple(struct scsi_device *sdev,
2480                           enum scsi_device_event evt_type, gfp_t gfpflags)
2481 {
2482         struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2483         if (!evt) {
2484                 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2485                             evt_type);
2486                 return;
2487         }
2488
2489         sdev_evt_send(sdev, evt);
2490 }
2491 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2492
2493 /**
2494  *      scsi_device_quiesce - Block user issued commands.
2495  *      @sdev:  scsi device to quiesce.
2496  *
2497  *      This works by trying to transition to the SDEV_QUIESCE state
2498  *      (which must be a legal transition).  When the device is in this
2499  *      state, only special requests will be accepted, all others will
2500  *      be deferred.  Since special requests may also be requeued requests,
2501  *      a successful return doesn't guarantee the device will be 
2502  *      totally quiescent.
2503  *
2504  *      Must be called with user context, may sleep.
2505  *
2506  *      Returns zero if unsuccessful or an error if not.
2507  */
2508 int
2509 scsi_device_quiesce(struct scsi_device *sdev)
2510 {
2511         int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2512         if (err)
2513                 return err;
2514
2515         scsi_run_queue(sdev->request_queue);
2516         while (sdev->device_busy) {
2517                 msleep_interruptible(200);
2518                 scsi_run_queue(sdev->request_queue);
2519         }
2520         return 0;
2521 }
2522 EXPORT_SYMBOL(scsi_device_quiesce);
2523
2524 /**
2525  *      scsi_device_resume - Restart user issued commands to a quiesced device.
2526  *      @sdev:  scsi device to resume.
2527  *
2528  *      Moves the device from quiesced back to running and restarts the
2529  *      queues.
2530  *
2531  *      Must be called with user context, may sleep.
2532  */
2533 void
2534 scsi_device_resume(struct scsi_device *sdev)
2535 {
2536         if(scsi_device_set_state(sdev, SDEV_RUNNING))
2537                 return;
2538         scsi_run_queue(sdev->request_queue);
2539 }
2540 EXPORT_SYMBOL(scsi_device_resume);
2541
2542 static void
2543 device_quiesce_fn(struct scsi_device *sdev, void *data)
2544 {
2545         scsi_device_quiesce(sdev);
2546 }
2547
2548 void
2549 scsi_target_quiesce(struct scsi_target *starget)
2550 {
2551         starget_for_each_device(starget, NULL, device_quiesce_fn);
2552 }
2553 EXPORT_SYMBOL(scsi_target_quiesce);
2554
2555 static void
2556 device_resume_fn(struct scsi_device *sdev, void *data)
2557 {
2558         scsi_device_resume(sdev);
2559 }
2560
2561 void
2562 scsi_target_resume(struct scsi_target *starget)
2563 {
2564         starget_for_each_device(starget, NULL, device_resume_fn);
2565 }
2566 EXPORT_SYMBOL(scsi_target_resume);
2567
2568 /**
2569  * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2570  * @sdev:       device to block
2571  *
2572  * Block request made by scsi lld's to temporarily stop all
2573  * scsi commands on the specified device.  Called from interrupt
2574  * or normal process context.
2575  *
2576  * Returns zero if successful or error if not
2577  *
2578  * Notes:       
2579  *      This routine transitions the device to the SDEV_BLOCK state
2580  *      (which must be a legal transition).  When the device is in this
2581  *      state, all commands are deferred until the scsi lld reenables
2582  *      the device with scsi_device_unblock or device_block_tmo fires.
2583  *      This routine assumes the host_lock is held on entry.
2584  */
2585 int
2586 scsi_internal_device_block(struct scsi_device *sdev)
2587 {
2588         struct request_queue *q = sdev->request_queue;
2589         unsigned long flags;
2590         int err = 0;
2591
2592         err = scsi_device_set_state(sdev, SDEV_BLOCK);
2593         if (err) {
2594                 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2595
2596                 if (err)
2597                         return err;
2598         }
2599
2600         /* 
2601          * The device has transitioned to SDEV_BLOCK.  Stop the
2602          * block layer from calling the midlayer with this device's
2603          * request queue. 
2604          */
2605         spin_lock_irqsave(q->queue_lock, flags);
2606         blk_stop_queue(q);
2607         spin_unlock_irqrestore(q->queue_lock, flags);
2608
2609         return 0;
2610 }
2611 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2612  
2613 /**
2614  * scsi_internal_device_unblock - resume a device after a block request
2615  * @sdev:       device to resume
2616  *
2617  * Called by scsi lld's or the midlayer to restart the device queue
2618  * for the previously suspended scsi device.  Called from interrupt or
2619  * normal process context.
2620  *
2621  * Returns zero if successful or error if not.
2622  *
2623  * Notes:       
2624  *      This routine transitions the device to the SDEV_RUNNING state
2625  *      (which must be a legal transition) allowing the midlayer to
2626  *      goose the queue for this device.  This routine assumes the 
2627  *      host_lock is held upon entry.
2628  */
2629 int
2630 scsi_internal_device_unblock(struct scsi_device *sdev)
2631 {
2632         struct request_queue *q = sdev->request_queue; 
2633         int err;
2634         unsigned long flags;
2635         
2636         /* 
2637          * Try to transition the scsi device to SDEV_RUNNING
2638          * and goose the device queue if successful.  
2639          */
2640         err = scsi_device_set_state(sdev, SDEV_RUNNING);
2641         if (err) {
2642                 err = scsi_device_set_state(sdev, SDEV_CREATED);
2643
2644                 if (err)
2645                         return err;
2646         }
2647
2648         spin_lock_irqsave(q->queue_lock, flags);
2649         blk_start_queue(q);
2650         spin_unlock_irqrestore(q->queue_lock, flags);
2651
2652         return 0;
2653 }
2654 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2655
2656 static void
2657 device_block(struct scsi_device *sdev, void *data)
2658 {
2659         scsi_internal_device_block(sdev);
2660 }
2661
2662 static int
2663 target_block(struct device *dev, void *data)
2664 {
2665         if (scsi_is_target_device(dev))
2666                 starget_for_each_device(to_scsi_target(dev), NULL,
2667                                         device_block);
2668         return 0;
2669 }
2670
2671 void
2672 scsi_target_block(struct device *dev)
2673 {
2674         if (scsi_is_target_device(dev))
2675                 starget_for_each_device(to_scsi_target(dev), NULL,
2676                                         device_block);
2677         else
2678                 device_for_each_child(dev, NULL, target_block);
2679 }
2680 EXPORT_SYMBOL_GPL(scsi_target_block);
2681
2682 static void
2683 device_unblock(struct scsi_device *sdev, void *data)
2684 {
2685         scsi_internal_device_unblock(sdev);
2686 }
2687
2688 static int
2689 target_unblock(struct device *dev, void *data)
2690 {
2691         if (scsi_is_target_device(dev))
2692                 starget_for_each_device(to_scsi_target(dev), NULL,
2693                                         device_unblock);
2694         return 0;
2695 }
2696
2697 void
2698 scsi_target_unblock(struct device *dev)
2699 {
2700         if (scsi_is_target_device(dev))
2701                 starget_for_each_device(to_scsi_target(dev), NULL,
2702                                         device_unblock);
2703         else
2704                 device_for_each_child(dev, NULL, target_unblock);
2705 }
2706 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2707
2708 /**
2709  * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2710  * @sgl:        scatter-gather list
2711  * @sg_count:   number of segments in sg
2712  * @offset:     offset in bytes into sg, on return offset into the mapped area
2713  * @len:        bytes to map, on return number of bytes mapped
2714  *
2715  * Returns virtual address of the start of the mapped page
2716  */
2717 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2718                           size_t *offset, size_t *len)
2719 {
2720         int i;
2721         size_t sg_len = 0, len_complete = 0;
2722         struct scatterlist *sg;
2723         struct page *page;
2724
2725         WARN_ON(!irqs_disabled());
2726
2727         for_each_sg(sgl, sg, sg_count, i) {
2728                 len_complete = sg_len; /* Complete sg-entries */
2729                 sg_len += sg->length;
2730                 if (sg_len > *offset)
2731                         break;
2732         }
2733
2734         if (unlikely(i == sg_count)) {
2735                 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2736                         "elements %d\n",
2737                        __func__, sg_len, *offset, sg_count);
2738                 WARN_ON(1);
2739                 return NULL;
2740         }
2741
2742         /* Offset starting from the beginning of first page in this sg-entry */
2743         *offset = *offset - len_complete + sg->offset;
2744
2745         /* Assumption: contiguous pages can be accessed as "page + i" */
2746         page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2747         *offset &= ~PAGE_MASK;
2748
2749         /* Bytes in this sg-entry from *offset to the end of the page */
2750         sg_len = PAGE_SIZE - *offset;
2751         if (*len > sg_len)
2752                 *len = sg_len;
2753
2754         return kmap_atomic(page, KM_BIO_SRC_IRQ);
2755 }
2756 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2757
2758 /**
2759  * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2760  * @virt:       virtual address to be unmapped
2761  */
2762 void scsi_kunmap_atomic_sg(void *virt)
2763 {
2764         kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2765 }
2766 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);