Merge branches 'sched/clock', 'sched/urgent' and 'linus' into sched/core
[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                         action = ACTION_FAIL;
1044                         if (sshdr.asc == 0x10) { /* DIF */
1045                                 description = "Target Data Integrity Failure";
1046                                 error = -EILSEQ;
1047                         }
1048                         break;
1049                 case NOT_READY:
1050                         /* If the device is in the process of becoming
1051                          * ready, or has a temporary blockage, retry.
1052                          */
1053                         if (sshdr.asc == 0x04) {
1054                                 switch (sshdr.ascq) {
1055                                 case 0x01: /* becoming ready */
1056                                 case 0x04: /* format in progress */
1057                                 case 0x05: /* rebuild in progress */
1058                                 case 0x06: /* recalculation in progress */
1059                                 case 0x07: /* operation in progress */
1060                                 case 0x08: /* Long write in progress */
1061                                 case 0x09: /* self test in progress */
1062                                         action = ACTION_DELAYED_RETRY;
1063                                         break;
1064                                 default:
1065                                         description = "Device not ready";
1066                                         action = ACTION_FAIL;
1067                                         break;
1068                                 }
1069                         } else {
1070                                 description = "Device not ready";
1071                                 action = ACTION_FAIL;
1072                         }
1073                         break;
1074                 case VOLUME_OVERFLOW:
1075                         /* See SSC3rXX or current. */
1076                         action = ACTION_FAIL;
1077                         break;
1078                 default:
1079                         description = "Unhandled sense code";
1080                         action = ACTION_FAIL;
1081                         break;
1082                 }
1083         } else {
1084                 description = "Unhandled error code";
1085                 action = ACTION_FAIL;
1086         }
1087
1088         switch (action) {
1089         case ACTION_FAIL:
1090                 /* Give up and fail the remainder of the request */
1091                 scsi_release_buffers(cmd);
1092                 if (!(req->cmd_flags & REQ_QUIET)) {
1093                         if (description)
1094                                 scmd_printk(KERN_INFO, cmd, "%s\n",
1095                                             description);
1096                         scsi_print_result(cmd);
1097                         if (driver_byte(result) & DRIVER_SENSE)
1098                                 scsi_print_sense("", cmd);
1099                 }
1100                 blk_end_request(req, -EIO, blk_rq_bytes(req));
1101                 scsi_next_command(cmd);
1102                 break;
1103         case ACTION_REPREP:
1104                 /* Unprep the request and put it back at the head of the queue.
1105                  * A new command will be prepared and issued.
1106                  */
1107                 scsi_release_buffers(cmd);
1108                 scsi_requeue_command(q, cmd);
1109                 break;
1110         case ACTION_RETRY:
1111                 /* Retry the same command immediately */
1112                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
1113                 break;
1114         case ACTION_DELAYED_RETRY:
1115                 /* Retry the same command after a delay */
1116                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
1117                 break;
1118         }
1119 }
1120
1121 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
1122                              gfp_t gfp_mask)
1123 {
1124         int count;
1125
1126         /*
1127          * If sg table allocation fails, requeue request later.
1128          */
1129         if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
1130                                         gfp_mask))) {
1131                 return BLKPREP_DEFER;
1132         }
1133
1134         req->buffer = NULL;
1135
1136         /* 
1137          * Next, walk the list, and fill in the addresses and sizes of
1138          * each segment.
1139          */
1140         count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1141         BUG_ON(count > sdb->table.nents);
1142         sdb->table.nents = count;
1143         if (blk_pc_request(req))
1144                 sdb->length = req->data_len;
1145         else
1146                 sdb->length = req->nr_sectors << 9;
1147         return BLKPREP_OK;
1148 }
1149
1150 /*
1151  * Function:    scsi_init_io()
1152  *
1153  * Purpose:     SCSI I/O initialize function.
1154  *
1155  * Arguments:   cmd   - Command descriptor we wish to initialize
1156  *
1157  * Returns:     0 on success
1158  *              BLKPREP_DEFER if the failure is retryable
1159  *              BLKPREP_KILL if the failure is fatal
1160  */
1161 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1162 {
1163         int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
1164         if (error)
1165                 goto err_exit;
1166
1167         if (blk_bidi_rq(cmd->request)) {
1168                 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1169                         scsi_sdb_cache, GFP_ATOMIC);
1170                 if (!bidi_sdb) {
1171                         error = BLKPREP_DEFER;
1172                         goto err_exit;
1173                 }
1174
1175                 cmd->request->next_rq->special = bidi_sdb;
1176                 error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
1177                                                                     GFP_ATOMIC);
1178                 if (error)
1179                         goto err_exit;
1180         }
1181
1182         if (blk_integrity_rq(cmd->request)) {
1183                 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1184                 int ivecs, count;
1185
1186                 BUG_ON(prot_sdb == NULL);
1187                 ivecs = blk_rq_count_integrity_sg(cmd->request);
1188
1189                 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1190                         error = BLKPREP_DEFER;
1191                         goto err_exit;
1192                 }
1193
1194                 count = blk_rq_map_integrity_sg(cmd->request,
1195                                                 prot_sdb->table.sgl);
1196                 BUG_ON(unlikely(count > ivecs));
1197
1198                 cmd->prot_sdb = prot_sdb;
1199                 cmd->prot_sdb->table.nents = count;
1200         }
1201
1202         return BLKPREP_OK ;
1203
1204 err_exit:
1205         scsi_release_buffers(cmd);
1206         if (error == BLKPREP_KILL)
1207                 scsi_put_command(cmd);
1208         else /* BLKPREP_DEFER */
1209                 scsi_unprep_request(cmd->request);
1210
1211         return error;
1212 }
1213 EXPORT_SYMBOL(scsi_init_io);
1214
1215 static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1216                 struct request *req)
1217 {
1218         struct scsi_cmnd *cmd;
1219
1220         if (!req->special) {
1221                 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1222                 if (unlikely(!cmd))
1223                         return NULL;
1224                 req->special = cmd;
1225         } else {
1226                 cmd = req->special;
1227         }
1228
1229         /* pull a tag out of the request if we have one */
1230         cmd->tag = req->tag;
1231         cmd->request = req;
1232
1233         cmd->cmnd = req->cmd;
1234
1235         return cmd;
1236 }
1237
1238 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1239 {
1240         struct scsi_cmnd *cmd;
1241         int ret = scsi_prep_state_check(sdev, req);
1242
1243         if (ret != BLKPREP_OK)
1244                 return ret;
1245
1246         cmd = scsi_get_cmd_from_req(sdev, req);
1247         if (unlikely(!cmd))
1248                 return BLKPREP_DEFER;
1249
1250         /*
1251          * BLOCK_PC requests may transfer data, in which case they must
1252          * a bio attached to them.  Or they might contain a SCSI command
1253          * that does not transfer data, in which case they may optionally
1254          * submit a request without an attached bio.
1255          */
1256         if (req->bio) {
1257                 int ret;
1258
1259                 BUG_ON(!req->nr_phys_segments);
1260
1261                 ret = scsi_init_io(cmd, GFP_ATOMIC);
1262                 if (unlikely(ret))
1263                         return ret;
1264         } else {
1265                 BUG_ON(req->data_len);
1266                 BUG_ON(req->data);
1267
1268                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1269                 req->buffer = NULL;
1270         }
1271
1272         cmd->cmd_len = req->cmd_len;
1273         if (!req->data_len)
1274                 cmd->sc_data_direction = DMA_NONE;
1275         else if (rq_data_dir(req) == WRITE)
1276                 cmd->sc_data_direction = DMA_TO_DEVICE;
1277         else
1278                 cmd->sc_data_direction = DMA_FROM_DEVICE;
1279         
1280         cmd->transfersize = req->data_len;
1281         cmd->allowed = req->retries;
1282         return BLKPREP_OK;
1283 }
1284 EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1285
1286 /*
1287  * Setup a REQ_TYPE_FS command.  These are simple read/write request
1288  * from filesystems that still need to be translated to SCSI CDBs from
1289  * the ULD.
1290  */
1291 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1292 {
1293         struct scsi_cmnd *cmd;
1294         int ret = scsi_prep_state_check(sdev, req);
1295
1296         if (ret != BLKPREP_OK)
1297                 return ret;
1298
1299         if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1300                          && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1301                 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1302                 if (ret != BLKPREP_OK)
1303                         return ret;
1304         }
1305
1306         /*
1307          * Filesystem requests must transfer data.
1308          */
1309         BUG_ON(!req->nr_phys_segments);
1310
1311         cmd = scsi_get_cmd_from_req(sdev, req);
1312         if (unlikely(!cmd))
1313                 return BLKPREP_DEFER;
1314
1315         memset(cmd->cmnd, 0, BLK_MAX_CDB);
1316         return scsi_init_io(cmd, GFP_ATOMIC);
1317 }
1318 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1319
1320 int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1321 {
1322         int ret = BLKPREP_OK;
1323
1324         /*
1325          * If the device is not in running state we will reject some
1326          * or all commands.
1327          */
1328         if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1329                 switch (sdev->sdev_state) {
1330                 case SDEV_OFFLINE:
1331                         /*
1332                          * If the device is offline we refuse to process any
1333                          * commands.  The device must be brought online
1334                          * before trying any recovery commands.
1335                          */
1336                         sdev_printk(KERN_ERR, sdev,
1337                                     "rejecting I/O to offline device\n");
1338                         ret = BLKPREP_KILL;
1339                         break;
1340                 case SDEV_DEL:
1341                         /*
1342                          * If the device is fully deleted, we refuse to
1343                          * process any commands as well.
1344                          */
1345                         sdev_printk(KERN_ERR, sdev,
1346                                     "rejecting I/O to dead device\n");
1347                         ret = BLKPREP_KILL;
1348                         break;
1349                 case SDEV_QUIESCE:
1350                 case SDEV_BLOCK:
1351                 case SDEV_CREATED_BLOCK:
1352                         /*
1353                          * If the devices is blocked we defer normal commands.
1354                          */
1355                         if (!(req->cmd_flags & REQ_PREEMPT))
1356                                 ret = BLKPREP_DEFER;
1357                         break;
1358                 default:
1359                         /*
1360                          * For any other not fully online state we only allow
1361                          * special commands.  In particular any user initiated
1362                          * command is not allowed.
1363                          */
1364                         if (!(req->cmd_flags & REQ_PREEMPT))
1365                                 ret = BLKPREP_KILL;
1366                         break;
1367                 }
1368         }
1369         return ret;
1370 }
1371 EXPORT_SYMBOL(scsi_prep_state_check);
1372
1373 int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1374 {
1375         struct scsi_device *sdev = q->queuedata;
1376
1377         switch (ret) {
1378         case BLKPREP_KILL:
1379                 req->errors = DID_NO_CONNECT << 16;
1380                 /* release the command and kill it */
1381                 if (req->special) {
1382                         struct scsi_cmnd *cmd = req->special;
1383                         scsi_release_buffers(cmd);
1384                         scsi_put_command(cmd);
1385                         req->special = NULL;
1386                 }
1387                 break;
1388         case BLKPREP_DEFER:
1389                 /*
1390                  * If we defer, the elv_next_request() returns NULL, but the
1391                  * queue must be restarted, so we plug here if no returning
1392                  * command will automatically do that.
1393                  */
1394                 if (sdev->device_busy == 0)
1395                         blk_plug_device(q);
1396                 break;
1397         default:
1398                 req->cmd_flags |= REQ_DONTPREP;
1399         }
1400
1401         return ret;
1402 }
1403 EXPORT_SYMBOL(scsi_prep_return);
1404
1405 int scsi_prep_fn(struct request_queue *q, struct request *req)
1406 {
1407         struct scsi_device *sdev = q->queuedata;
1408         int ret = BLKPREP_KILL;
1409
1410         if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1411                 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1412         return scsi_prep_return(q, req, ret);
1413 }
1414
1415 /*
1416  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1417  * return 0.
1418  *
1419  * Called with the queue_lock held.
1420  */
1421 static inline int scsi_dev_queue_ready(struct request_queue *q,
1422                                   struct scsi_device *sdev)
1423 {
1424         if (sdev->device_busy == 0 && sdev->device_blocked) {
1425                 /*
1426                  * unblock after device_blocked iterates to zero
1427                  */
1428                 if (--sdev->device_blocked == 0) {
1429                         SCSI_LOG_MLQUEUE(3,
1430                                    sdev_printk(KERN_INFO, sdev,
1431                                    "unblocking device at zero depth\n"));
1432                 } else {
1433                         blk_plug_device(q);
1434                         return 0;
1435                 }
1436         }
1437         if (scsi_device_is_busy(sdev))
1438                 return 0;
1439
1440         return 1;
1441 }
1442
1443
1444 /*
1445  * scsi_target_queue_ready: checks if there we can send commands to target
1446  * @sdev: scsi device on starget to check.
1447  *
1448  * Called with the host lock held.
1449  */
1450 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1451                                            struct scsi_device *sdev)
1452 {
1453         struct scsi_target *starget = scsi_target(sdev);
1454
1455         if (starget->single_lun) {
1456                 if (starget->starget_sdev_user &&
1457                     starget->starget_sdev_user != sdev)
1458                         return 0;
1459                 starget->starget_sdev_user = sdev;
1460         }
1461
1462         if (starget->target_busy == 0 && starget->target_blocked) {
1463                 /*
1464                  * unblock after target_blocked iterates to zero
1465                  */
1466                 if (--starget->target_blocked == 0) {
1467                         SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1468                                          "unblocking target at zero depth\n"));
1469                 } else {
1470                         blk_plug_device(sdev->request_queue);
1471                         return 0;
1472                 }
1473         }
1474
1475         if (scsi_target_is_busy(starget)) {
1476                 if (list_empty(&sdev->starved_entry)) {
1477                         list_add_tail(&sdev->starved_entry,
1478                                       &shost->starved_list);
1479                         return 0;
1480                 }
1481         }
1482
1483         /* We're OK to process the command, so we can't be starved */
1484         if (!list_empty(&sdev->starved_entry))
1485                 list_del_init(&sdev->starved_entry);
1486         return 1;
1487 }
1488
1489 /*
1490  * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1491  * return 0. We must end up running the queue again whenever 0 is
1492  * returned, else IO can hang.
1493  *
1494  * Called with host_lock held.
1495  */
1496 static inline int scsi_host_queue_ready(struct request_queue *q,
1497                                    struct Scsi_Host *shost,
1498                                    struct scsi_device *sdev)
1499 {
1500         if (scsi_host_in_recovery(shost))
1501                 return 0;
1502         if (shost->host_busy == 0 && shost->host_blocked) {
1503                 /*
1504                  * unblock after host_blocked iterates to zero
1505                  */
1506                 if (--shost->host_blocked == 0) {
1507                         SCSI_LOG_MLQUEUE(3,
1508                                 printk("scsi%d unblocking host at zero depth\n",
1509                                         shost->host_no));
1510                 } else {
1511                         return 0;
1512                 }
1513         }
1514         if (scsi_host_is_busy(shost)) {
1515                 if (list_empty(&sdev->starved_entry))
1516                         list_add_tail(&sdev->starved_entry, &shost->starved_list);
1517                 return 0;
1518         }
1519
1520         /* We're OK to process the command, so we can't be starved */
1521         if (!list_empty(&sdev->starved_entry))
1522                 list_del_init(&sdev->starved_entry);
1523
1524         return 1;
1525 }
1526
1527 /*
1528  * Busy state exporting function for request stacking drivers.
1529  *
1530  * For efficiency, no lock is taken to check the busy state of
1531  * shost/starget/sdev, since the returned value is not guaranteed and
1532  * may be changed after request stacking drivers call the function,
1533  * regardless of taking lock or not.
1534  *
1535  * When scsi can't dispatch I/Os anymore and needs to kill I/Os
1536  * (e.g. !sdev), scsi needs to return 'not busy'.
1537  * Otherwise, request stacking drivers may hold requests forever.
1538  */
1539 static int scsi_lld_busy(struct request_queue *q)
1540 {
1541         struct scsi_device *sdev = q->queuedata;
1542         struct Scsi_Host *shost;
1543         struct scsi_target *starget;
1544
1545         if (!sdev)
1546                 return 0;
1547
1548         shost = sdev->host;
1549         starget = scsi_target(sdev);
1550
1551         if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
1552             scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
1553                 return 1;
1554
1555         return 0;
1556 }
1557
1558 /*
1559  * Kill a request for a dead device
1560  */
1561 static void scsi_kill_request(struct request *req, struct request_queue *q)
1562 {
1563         struct scsi_cmnd *cmd = req->special;
1564         struct scsi_device *sdev = cmd->device;
1565         struct scsi_target *starget = scsi_target(sdev);
1566         struct Scsi_Host *shost = sdev->host;
1567
1568         blkdev_dequeue_request(req);
1569
1570         if (unlikely(cmd == NULL)) {
1571                 printk(KERN_CRIT "impossible request in %s.\n",
1572                                  __func__);
1573                 BUG();
1574         }
1575
1576         scsi_init_cmd_errh(cmd);
1577         cmd->result = DID_NO_CONNECT << 16;
1578         atomic_inc(&cmd->device->iorequest_cnt);
1579
1580         /*
1581          * SCSI request completion path will do scsi_device_unbusy(),
1582          * bump busy counts.  To bump the counters, we need to dance
1583          * with the locks as normal issue path does.
1584          */
1585         sdev->device_busy++;
1586         spin_unlock(sdev->request_queue->queue_lock);
1587         spin_lock(shost->host_lock);
1588         shost->host_busy++;
1589         starget->target_busy++;
1590         spin_unlock(shost->host_lock);
1591         spin_lock(sdev->request_queue->queue_lock);
1592
1593         blk_complete_request(req);
1594 }
1595
1596 static void scsi_softirq_done(struct request *rq)
1597 {
1598         struct scsi_cmnd *cmd = rq->special;
1599         unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1600         int disposition;
1601
1602         INIT_LIST_HEAD(&cmd->eh_entry);
1603
1604         /*
1605          * Set the serial numbers back to zero
1606          */
1607         cmd->serial_number = 0;
1608
1609         atomic_inc(&cmd->device->iodone_cnt);
1610         if (cmd->result)
1611                 atomic_inc(&cmd->device->ioerr_cnt);
1612
1613         disposition = scsi_decide_disposition(cmd);
1614         if (disposition != SUCCESS &&
1615             time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1616                 sdev_printk(KERN_ERR, cmd->device,
1617                             "timing out command, waited %lus\n",
1618                             wait_for/HZ);
1619                 disposition = SUCCESS;
1620         }
1621                         
1622         scsi_log_completion(cmd, disposition);
1623
1624         switch (disposition) {
1625                 case SUCCESS:
1626                         scsi_finish_command(cmd);
1627                         break;
1628                 case NEEDS_RETRY:
1629                         scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1630                         break;
1631                 case ADD_TO_MLQUEUE:
1632                         scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1633                         break;
1634                 default:
1635                         if (!scsi_eh_scmd_add(cmd, 0))
1636                                 scsi_finish_command(cmd);
1637         }
1638 }
1639
1640 /*
1641  * Function:    scsi_request_fn()
1642  *
1643  * Purpose:     Main strategy routine for SCSI.
1644  *
1645  * Arguments:   q       - Pointer to actual queue.
1646  *
1647  * Returns:     Nothing
1648  *
1649  * Lock status: IO request lock assumed to be held when called.
1650  */
1651 static void scsi_request_fn(struct request_queue *q)
1652 {
1653         struct scsi_device *sdev = q->queuedata;
1654         struct Scsi_Host *shost;
1655         struct scsi_cmnd *cmd;
1656         struct request *req;
1657
1658         if (!sdev) {
1659                 printk("scsi: killing requests for dead queue\n");
1660                 while ((req = elv_next_request(q)) != NULL)
1661                         scsi_kill_request(req, q);
1662                 return;
1663         }
1664
1665         if(!get_device(&sdev->sdev_gendev))
1666                 /* We must be tearing the block queue down already */
1667                 return;
1668
1669         /*
1670          * To start with, we keep looping until the queue is empty, or until
1671          * the host is no longer able to accept any more requests.
1672          */
1673         shost = sdev->host;
1674         while (!blk_queue_plugged(q)) {
1675                 int rtn;
1676                 /*
1677                  * get next queueable request.  We do this early to make sure
1678                  * that the request is fully prepared even if we cannot 
1679                  * accept it.
1680                  */
1681                 req = elv_next_request(q);
1682                 if (!req || !scsi_dev_queue_ready(q, sdev))
1683                         break;
1684
1685                 if (unlikely(!scsi_device_online(sdev))) {
1686                         sdev_printk(KERN_ERR, sdev,
1687                                     "rejecting I/O to offline device\n");
1688                         scsi_kill_request(req, q);
1689                         continue;
1690                 }
1691
1692
1693                 /*
1694                  * Remove the request from the request list.
1695                  */
1696                 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1697                         blkdev_dequeue_request(req);
1698                 sdev->device_busy++;
1699
1700                 spin_unlock(q->queue_lock);
1701                 cmd = req->special;
1702                 if (unlikely(cmd == NULL)) {
1703                         printk(KERN_CRIT "impossible request in %s.\n"
1704                                          "please mail a stack trace to "
1705                                          "linux-scsi@vger.kernel.org\n",
1706                                          __func__);
1707                         blk_dump_rq_flags(req, "foo");
1708                         BUG();
1709                 }
1710                 spin_lock(shost->host_lock);
1711
1712                 /*
1713                  * We hit this when the driver is using a host wide
1714                  * tag map. For device level tag maps the queue_depth check
1715                  * in the device ready fn would prevent us from trying
1716                  * to allocate a tag. Since the map is a shared host resource
1717                  * we add the dev to the starved list so it eventually gets
1718                  * a run when a tag is freed.
1719                  */
1720                 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1721                         if (list_empty(&sdev->starved_entry))
1722                                 list_add_tail(&sdev->starved_entry,
1723                                               &shost->starved_list);
1724                         goto not_ready;
1725                 }
1726
1727                 if (!scsi_target_queue_ready(shost, sdev))
1728                         goto not_ready;
1729
1730                 if (!scsi_host_queue_ready(q, shost, sdev))
1731                         goto not_ready;
1732
1733                 scsi_target(sdev)->target_busy++;
1734                 shost->host_busy++;
1735
1736                 /*
1737                  * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1738                  *              take the lock again.
1739                  */
1740                 spin_unlock_irq(shost->host_lock);
1741
1742                 /*
1743                  * Finally, initialize any error handling parameters, and set up
1744                  * the timers for timeouts.
1745                  */
1746                 scsi_init_cmd_errh(cmd);
1747
1748                 /*
1749                  * Dispatch the command to the low-level driver.
1750                  */
1751                 rtn = scsi_dispatch_cmd(cmd);
1752                 spin_lock_irq(q->queue_lock);
1753                 if(rtn) {
1754                         /* we're refusing the command; because of
1755                          * the way locks get dropped, we need to 
1756                          * check here if plugging is required */
1757                         if(sdev->device_busy == 0)
1758                                 blk_plug_device(q);
1759
1760                         break;
1761                 }
1762         }
1763
1764         goto out;
1765
1766  not_ready:
1767         spin_unlock_irq(shost->host_lock);
1768
1769         /*
1770          * lock q, handle tag, requeue req, and decrement device_busy. We
1771          * must return with queue_lock held.
1772          *
1773          * Decrementing device_busy without checking it is OK, as all such
1774          * cases (host limits or settings) should run the queue at some
1775          * later time.
1776          */
1777         spin_lock_irq(q->queue_lock);
1778         blk_requeue_request(q, req);
1779         sdev->device_busy--;
1780         if(sdev->device_busy == 0)
1781                 blk_plug_device(q);
1782  out:
1783         /* must be careful here...if we trigger the ->remove() function
1784          * we cannot be holding the q lock */
1785         spin_unlock_irq(q->queue_lock);
1786         put_device(&sdev->sdev_gendev);
1787         spin_lock_irq(q->queue_lock);
1788 }
1789
1790 u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1791 {
1792         struct device *host_dev;
1793         u64 bounce_limit = 0xffffffff;
1794
1795         if (shost->unchecked_isa_dma)
1796                 return BLK_BOUNCE_ISA;
1797         /*
1798          * Platforms with virtual-DMA translation
1799          * hardware have no practical limit.
1800          */
1801         if (!PCI_DMA_BUS_IS_PHYS)
1802                 return BLK_BOUNCE_ANY;
1803
1804         host_dev = scsi_get_device(shost);
1805         if (host_dev && host_dev->dma_mask)
1806                 bounce_limit = *host_dev->dma_mask;
1807
1808         return bounce_limit;
1809 }
1810 EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1811
1812 struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1813                                          request_fn_proc *request_fn)
1814 {
1815         struct request_queue *q;
1816         struct device *dev = shost->shost_gendev.parent;
1817
1818         q = blk_init_queue(request_fn, NULL);
1819         if (!q)
1820                 return NULL;
1821
1822         /*
1823          * this limit is imposed by hardware restrictions
1824          */
1825         blk_queue_max_hw_segments(q, shost->sg_tablesize);
1826         blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
1827
1828         blk_queue_max_sectors(q, shost->max_sectors);
1829         blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1830         blk_queue_segment_boundary(q, shost->dma_boundary);
1831         dma_set_seg_boundary(dev, shost->dma_boundary);
1832
1833         blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1834
1835         /* New queue, no concurrency on queue_flags */
1836         if (!shost->use_clustering)
1837                 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
1838
1839         /*
1840          * set a reasonable default alignment on word boundaries: the
1841          * host and device may alter it using
1842          * blk_queue_update_dma_alignment() later.
1843          */
1844         blk_queue_dma_alignment(q, 0x03);
1845
1846         return q;
1847 }
1848 EXPORT_SYMBOL(__scsi_alloc_queue);
1849
1850 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1851 {
1852         struct request_queue *q;
1853
1854         q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1855         if (!q)
1856                 return NULL;
1857
1858         blk_queue_prep_rq(q, scsi_prep_fn);
1859         blk_queue_softirq_done(q, scsi_softirq_done);
1860         blk_queue_rq_timed_out(q, scsi_times_out);
1861         blk_queue_lld_busy(q, scsi_lld_busy);
1862         return q;
1863 }
1864
1865 void scsi_free_queue(struct request_queue *q)
1866 {
1867         blk_cleanup_queue(q);
1868 }
1869
1870 /*
1871  * Function:    scsi_block_requests()
1872  *
1873  * Purpose:     Utility function used by low-level drivers to prevent further
1874  *              commands from being queued to the device.
1875  *
1876  * Arguments:   shost       - Host in question
1877  *
1878  * Returns:     Nothing
1879  *
1880  * Lock status: No locks are assumed held.
1881  *
1882  * Notes:       There is no timer nor any other means by which the requests
1883  *              get unblocked other than the low-level driver calling
1884  *              scsi_unblock_requests().
1885  */
1886 void scsi_block_requests(struct Scsi_Host *shost)
1887 {
1888         shost->host_self_blocked = 1;
1889 }
1890 EXPORT_SYMBOL(scsi_block_requests);
1891
1892 /*
1893  * Function:    scsi_unblock_requests()
1894  *
1895  * Purpose:     Utility function used by low-level drivers to allow further
1896  *              commands from being queued to the device.
1897  *
1898  * Arguments:   shost       - Host in question
1899  *
1900  * Returns:     Nothing
1901  *
1902  * Lock status: No locks are assumed held.
1903  *
1904  * Notes:       There is no timer nor any other means by which the requests
1905  *              get unblocked other than the low-level driver calling
1906  *              scsi_unblock_requests().
1907  *
1908  *              This is done as an API function so that changes to the
1909  *              internals of the scsi mid-layer won't require wholesale
1910  *              changes to drivers that use this feature.
1911  */
1912 void scsi_unblock_requests(struct Scsi_Host *shost)
1913 {
1914         shost->host_self_blocked = 0;
1915         scsi_run_host_queues(shost);
1916 }
1917 EXPORT_SYMBOL(scsi_unblock_requests);
1918
1919 int __init scsi_init_queue(void)
1920 {
1921         int i;
1922
1923         scsi_io_context_cache = kmem_cache_create("scsi_io_context",
1924                                         sizeof(struct scsi_io_context),
1925                                         0, 0, NULL);
1926         if (!scsi_io_context_cache) {
1927                 printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
1928                 return -ENOMEM;
1929         }
1930
1931         scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1932                                            sizeof(struct scsi_data_buffer),
1933                                            0, 0, NULL);
1934         if (!scsi_sdb_cache) {
1935                 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1936                 goto cleanup_io_context;
1937         }
1938
1939         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1940                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1941                 int size = sgp->size * sizeof(struct scatterlist);
1942
1943                 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1944                                 SLAB_HWCACHE_ALIGN, NULL);
1945                 if (!sgp->slab) {
1946                         printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1947                                         sgp->name);
1948                         goto cleanup_sdb;
1949                 }
1950
1951                 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1952                                                      sgp->slab);
1953                 if (!sgp->pool) {
1954                         printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1955                                         sgp->name);
1956                         goto cleanup_sdb;
1957                 }
1958         }
1959
1960         return 0;
1961
1962 cleanup_sdb:
1963         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1964                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1965                 if (sgp->pool)
1966                         mempool_destroy(sgp->pool);
1967                 if (sgp->slab)
1968                         kmem_cache_destroy(sgp->slab);
1969         }
1970         kmem_cache_destroy(scsi_sdb_cache);
1971 cleanup_io_context:
1972         kmem_cache_destroy(scsi_io_context_cache);
1973
1974         return -ENOMEM;
1975 }
1976
1977 void scsi_exit_queue(void)
1978 {
1979         int i;
1980
1981         kmem_cache_destroy(scsi_io_context_cache);
1982         kmem_cache_destroy(scsi_sdb_cache);
1983
1984         for (i = 0; i < SG_MEMPOOL_NR; i++) {
1985                 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1986                 mempool_destroy(sgp->pool);
1987                 kmem_cache_destroy(sgp->slab);
1988         }
1989 }
1990
1991 /**
1992  *      scsi_mode_select - issue a mode select
1993  *      @sdev:  SCSI device to be queried
1994  *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
1995  *      @sp:    Save page bit (0 == don't save, 1 == save)
1996  *      @modepage: mode page being requested
1997  *      @buffer: request buffer (may not be smaller than eight bytes)
1998  *      @len:   length of request buffer.
1999  *      @timeout: command timeout
2000  *      @retries: number of retries before failing
2001  *      @data: returns a structure abstracting the mode header data
2002  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2003  *              must be SCSI_SENSE_BUFFERSIZE big.
2004  *
2005  *      Returns zero if successful; negative error number or scsi
2006  *      status on error
2007  *
2008  */
2009 int
2010 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
2011                  unsigned char *buffer, int len, int timeout, int retries,
2012                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2013 {
2014         unsigned char cmd[10];
2015         unsigned char *real_buffer;
2016         int ret;
2017
2018         memset(cmd, 0, sizeof(cmd));
2019         cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
2020
2021         if (sdev->use_10_for_ms) {
2022                 if (len > 65535)
2023                         return -EINVAL;
2024                 real_buffer = kmalloc(8 + len, GFP_KERNEL);
2025                 if (!real_buffer)
2026                         return -ENOMEM;
2027                 memcpy(real_buffer + 8, buffer, len);
2028                 len += 8;
2029                 real_buffer[0] = 0;
2030                 real_buffer[1] = 0;
2031                 real_buffer[2] = data->medium_type;
2032                 real_buffer[3] = data->device_specific;
2033                 real_buffer[4] = data->longlba ? 0x01 : 0;
2034                 real_buffer[5] = 0;
2035                 real_buffer[6] = data->block_descriptor_length >> 8;
2036                 real_buffer[7] = data->block_descriptor_length;
2037
2038                 cmd[0] = MODE_SELECT_10;
2039                 cmd[7] = len >> 8;
2040                 cmd[8] = len;
2041         } else {
2042                 if (len > 255 || data->block_descriptor_length > 255 ||
2043                     data->longlba)
2044                         return -EINVAL;
2045
2046                 real_buffer = kmalloc(4 + len, GFP_KERNEL);
2047                 if (!real_buffer)
2048                         return -ENOMEM;
2049                 memcpy(real_buffer + 4, buffer, len);
2050                 len += 4;
2051                 real_buffer[0] = 0;
2052                 real_buffer[1] = data->medium_type;
2053                 real_buffer[2] = data->device_specific;
2054                 real_buffer[3] = data->block_descriptor_length;
2055                 
2056
2057                 cmd[0] = MODE_SELECT;
2058                 cmd[4] = len;
2059         }
2060
2061         ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2062                                sshdr, timeout, retries, NULL);
2063         kfree(real_buffer);
2064         return ret;
2065 }
2066 EXPORT_SYMBOL_GPL(scsi_mode_select);
2067
2068 /**
2069  *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2070  *      @sdev:  SCSI device to be queried
2071  *      @dbd:   set if mode sense will allow block descriptors to be returned
2072  *      @modepage: mode page being requested
2073  *      @buffer: request buffer (may not be smaller than eight bytes)
2074  *      @len:   length of request buffer.
2075  *      @timeout: command timeout
2076  *      @retries: number of retries before failing
2077  *      @data: returns a structure abstracting the mode header data
2078  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2079  *              must be SCSI_SENSE_BUFFERSIZE big.
2080  *
2081  *      Returns zero if unsuccessful, or the header offset (either 4
2082  *      or 8 depending on whether a six or ten byte command was
2083  *      issued) if successful.
2084  */
2085 int
2086 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2087                   unsigned char *buffer, int len, int timeout, int retries,
2088                   struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2089 {
2090         unsigned char cmd[12];
2091         int use_10_for_ms;
2092         int header_length;
2093         int result;
2094         struct scsi_sense_hdr my_sshdr;
2095
2096         memset(data, 0, sizeof(*data));
2097         memset(&cmd[0], 0, 12);
2098         cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
2099         cmd[2] = modepage;
2100
2101         /* caller might not be interested in sense, but we need it */
2102         if (!sshdr)
2103                 sshdr = &my_sshdr;
2104
2105  retry:
2106         use_10_for_ms = sdev->use_10_for_ms;
2107
2108         if (use_10_for_ms) {
2109                 if (len < 8)
2110                         len = 8;
2111
2112                 cmd[0] = MODE_SENSE_10;
2113                 cmd[8] = len;
2114                 header_length = 8;
2115         } else {
2116                 if (len < 4)
2117                         len = 4;
2118
2119                 cmd[0] = MODE_SENSE;
2120                 cmd[4] = len;
2121                 header_length = 4;
2122         }
2123
2124         memset(buffer, 0, len);
2125
2126         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2127                                   sshdr, timeout, retries, NULL);
2128
2129         /* This code looks awful: what it's doing is making sure an
2130          * ILLEGAL REQUEST sense return identifies the actual command
2131          * byte as the problem.  MODE_SENSE commands can return
2132          * ILLEGAL REQUEST if the code page isn't supported */
2133
2134         if (use_10_for_ms && !scsi_status_is_good(result) &&
2135             (driver_byte(result) & DRIVER_SENSE)) {
2136                 if (scsi_sense_valid(sshdr)) {
2137                         if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2138                             (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2139                                 /* 
2140                                  * Invalid command operation code
2141                                  */
2142                                 sdev->use_10_for_ms = 0;
2143                                 goto retry;
2144                         }
2145                 }
2146         }
2147
2148         if(scsi_status_is_good(result)) {
2149                 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2150                              (modepage == 6 || modepage == 8))) {
2151                         /* Initio breakage? */
2152                         header_length = 0;
2153                         data->length = 13;
2154                         data->medium_type = 0;
2155                         data->device_specific = 0;
2156                         data->longlba = 0;
2157                         data->block_descriptor_length = 0;
2158                 } else if(use_10_for_ms) {
2159                         data->length = buffer[0]*256 + buffer[1] + 2;
2160                         data->medium_type = buffer[2];
2161                         data->device_specific = buffer[3];
2162                         data->longlba = buffer[4] & 0x01;
2163                         data->block_descriptor_length = buffer[6]*256
2164                                 + buffer[7];
2165                 } else {
2166                         data->length = buffer[0] + 1;
2167                         data->medium_type = buffer[1];
2168                         data->device_specific = buffer[2];
2169                         data->block_descriptor_length = buffer[3];
2170                 }
2171                 data->header_length = header_length;
2172         }
2173
2174         return result;
2175 }
2176 EXPORT_SYMBOL(scsi_mode_sense);
2177
2178 /**
2179  *      scsi_test_unit_ready - test if unit is ready
2180  *      @sdev:  scsi device to change the state of.
2181  *      @timeout: command timeout
2182  *      @retries: number of retries before failing
2183  *      @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2184  *              returning sense. Make sure that this is cleared before passing
2185  *              in.
2186  *
2187  *      Returns zero if unsuccessful or an error if TUR failed.  For
2188  *      removable media, a return of NOT_READY or UNIT_ATTENTION is
2189  *      translated to success, with the ->changed flag updated.
2190  **/
2191 int
2192 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2193                      struct scsi_sense_hdr *sshdr_external)
2194 {
2195         char cmd[] = {
2196                 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2197         };
2198         struct scsi_sense_hdr *sshdr;
2199         int result;
2200
2201         if (!sshdr_external)
2202                 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2203         else
2204                 sshdr = sshdr_external;
2205
2206         /* try to eat the UNIT_ATTENTION if there are enough retries */
2207         do {
2208                 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2209                                           timeout, retries, NULL);
2210                 if (sdev->removable && scsi_sense_valid(sshdr) &&
2211                     sshdr->sense_key == UNIT_ATTENTION)
2212                         sdev->changed = 1;
2213         } while (scsi_sense_valid(sshdr) &&
2214                  sshdr->sense_key == UNIT_ATTENTION && --retries);
2215
2216         if (!sshdr)
2217                 /* could not allocate sense buffer, so can't process it */
2218                 return result;
2219
2220         if (sdev->removable && scsi_sense_valid(sshdr) &&
2221             (sshdr->sense_key == UNIT_ATTENTION ||
2222              sshdr->sense_key == NOT_READY)) {
2223                 sdev->changed = 1;
2224                 result = 0;
2225         }
2226         if (!sshdr_external)
2227                 kfree(sshdr);
2228         return result;
2229 }
2230 EXPORT_SYMBOL(scsi_test_unit_ready);
2231
2232 /**
2233  *      scsi_device_set_state - Take the given device through the device state model.
2234  *      @sdev:  scsi device to change the state of.
2235  *      @state: state to change to.
2236  *
2237  *      Returns zero if unsuccessful or an error if the requested 
2238  *      transition is illegal.
2239  */
2240 int
2241 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2242 {
2243         enum scsi_device_state oldstate = sdev->sdev_state;
2244
2245         if (state == oldstate)
2246                 return 0;
2247
2248         switch (state) {
2249         case SDEV_CREATED:
2250                 switch (oldstate) {
2251                 case SDEV_CREATED_BLOCK:
2252                         break;
2253                 default:
2254                         goto illegal;
2255                 }
2256                 break;
2257                         
2258         case SDEV_RUNNING:
2259                 switch (oldstate) {
2260                 case SDEV_CREATED:
2261                 case SDEV_OFFLINE:
2262                 case SDEV_QUIESCE:
2263                 case SDEV_BLOCK:
2264                         break;
2265                 default:
2266                         goto illegal;
2267                 }
2268                 break;
2269
2270         case SDEV_QUIESCE:
2271                 switch (oldstate) {
2272                 case SDEV_RUNNING:
2273                 case SDEV_OFFLINE:
2274                         break;
2275                 default:
2276                         goto illegal;
2277                 }
2278                 break;
2279
2280         case SDEV_OFFLINE:
2281                 switch (oldstate) {
2282                 case SDEV_CREATED:
2283                 case SDEV_RUNNING:
2284                 case SDEV_QUIESCE:
2285                 case SDEV_BLOCK:
2286                         break;
2287                 default:
2288                         goto illegal;
2289                 }
2290                 break;
2291
2292         case SDEV_BLOCK:
2293                 switch (oldstate) {
2294                 case SDEV_RUNNING:
2295                 case SDEV_CREATED_BLOCK:
2296                         break;
2297                 default:
2298                         goto illegal;
2299                 }
2300                 break;
2301
2302         case SDEV_CREATED_BLOCK:
2303                 switch (oldstate) {
2304                 case SDEV_CREATED:
2305                         break;
2306                 default:
2307                         goto illegal;
2308                 }
2309                 break;
2310
2311         case SDEV_CANCEL:
2312                 switch (oldstate) {
2313                 case SDEV_CREATED:
2314                 case SDEV_RUNNING:
2315                 case SDEV_QUIESCE:
2316                 case SDEV_OFFLINE:
2317                 case SDEV_BLOCK:
2318                         break;
2319                 default:
2320                         goto illegal;
2321                 }
2322                 break;
2323
2324         case SDEV_DEL:
2325                 switch (oldstate) {
2326                 case SDEV_CREATED:
2327                 case SDEV_RUNNING:
2328                 case SDEV_OFFLINE:
2329                 case SDEV_CANCEL:
2330                         break;
2331                 default:
2332                         goto illegal;
2333                 }
2334                 break;
2335
2336         }
2337         sdev->sdev_state = state;
2338         return 0;
2339
2340  illegal:
2341         SCSI_LOG_ERROR_RECOVERY(1, 
2342                                 sdev_printk(KERN_ERR, sdev,
2343                                             "Illegal state transition %s->%s\n",
2344                                             scsi_device_state_name(oldstate),
2345                                             scsi_device_state_name(state))
2346                                 );
2347         return -EINVAL;
2348 }
2349 EXPORT_SYMBOL(scsi_device_set_state);
2350
2351 /**
2352  *      sdev_evt_emit - emit a single SCSI device uevent
2353  *      @sdev: associated SCSI device
2354  *      @evt: event to emit
2355  *
2356  *      Send a single uevent (scsi_event) to the associated scsi_device.
2357  */
2358 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2359 {
2360         int idx = 0;
2361         char *envp[3];
2362
2363         switch (evt->evt_type) {
2364         case SDEV_EVT_MEDIA_CHANGE:
2365                 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2366                 break;
2367
2368         default:
2369                 /* do nothing */
2370                 break;
2371         }
2372
2373         envp[idx++] = NULL;
2374
2375         kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2376 }
2377
2378 /**
2379  *      sdev_evt_thread - send a uevent for each scsi event
2380  *      @work: work struct for scsi_device
2381  *
2382  *      Dispatch queued events to their associated scsi_device kobjects
2383  *      as uevents.
2384  */
2385 void scsi_evt_thread(struct work_struct *work)
2386 {
2387         struct scsi_device *sdev;
2388         LIST_HEAD(event_list);
2389
2390         sdev = container_of(work, struct scsi_device, event_work);
2391
2392         while (1) {
2393                 struct scsi_event *evt;
2394                 struct list_head *this, *tmp;
2395                 unsigned long flags;
2396
2397                 spin_lock_irqsave(&sdev->list_lock, flags);
2398                 list_splice_init(&sdev->event_list, &event_list);
2399                 spin_unlock_irqrestore(&sdev->list_lock, flags);
2400
2401                 if (list_empty(&event_list))
2402                         break;
2403
2404                 list_for_each_safe(this, tmp, &event_list) {
2405                         evt = list_entry(this, struct scsi_event, node);
2406                         list_del(&evt->node);
2407                         scsi_evt_emit(sdev, evt);
2408                         kfree(evt);
2409                 }
2410         }
2411 }
2412
2413 /**
2414  *      sdev_evt_send - send asserted event to uevent thread
2415  *      @sdev: scsi_device event occurred on
2416  *      @evt: event to send
2417  *
2418  *      Assert scsi device event asynchronously.
2419  */
2420 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2421 {
2422         unsigned long flags;
2423
2424 #if 0
2425         /* FIXME: currently this check eliminates all media change events
2426          * for polled devices.  Need to update to discriminate between AN
2427          * and polled events */
2428         if (!test_bit(evt->evt_type, sdev->supported_events)) {
2429                 kfree(evt);
2430                 return;
2431         }
2432 #endif
2433
2434         spin_lock_irqsave(&sdev->list_lock, flags);
2435         list_add_tail(&evt->node, &sdev->event_list);
2436         schedule_work(&sdev->event_work);
2437         spin_unlock_irqrestore(&sdev->list_lock, flags);
2438 }
2439 EXPORT_SYMBOL_GPL(sdev_evt_send);
2440
2441 /**
2442  *      sdev_evt_alloc - allocate a new scsi event
2443  *      @evt_type: type of event to allocate
2444  *      @gfpflags: GFP flags for allocation
2445  *
2446  *      Allocates and returns a new scsi_event.
2447  */
2448 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2449                                   gfp_t gfpflags)
2450 {
2451         struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2452         if (!evt)
2453                 return NULL;
2454
2455         evt->evt_type = evt_type;
2456         INIT_LIST_HEAD(&evt->node);
2457
2458         /* evt_type-specific initialization, if any */
2459         switch (evt_type) {
2460         case SDEV_EVT_MEDIA_CHANGE:
2461         default:
2462                 /* do nothing */
2463                 break;
2464         }
2465
2466         return evt;
2467 }
2468 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2469
2470 /**
2471  *      sdev_evt_send_simple - send asserted event to uevent thread
2472  *      @sdev: scsi_device event occurred on
2473  *      @evt_type: type of event to send
2474  *      @gfpflags: GFP flags for allocation
2475  *
2476  *      Assert scsi device event asynchronously, given an event type.
2477  */
2478 void sdev_evt_send_simple(struct scsi_device *sdev,
2479                           enum scsi_device_event evt_type, gfp_t gfpflags)
2480 {
2481         struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2482         if (!evt) {
2483                 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2484                             evt_type);
2485                 return;
2486         }
2487
2488         sdev_evt_send(sdev, evt);
2489 }
2490 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2491
2492 /**
2493  *      scsi_device_quiesce - Block user issued commands.
2494  *      @sdev:  scsi device to quiesce.
2495  *
2496  *      This works by trying to transition to the SDEV_QUIESCE state
2497  *      (which must be a legal transition).  When the device is in this
2498  *      state, only special requests will be accepted, all others will
2499  *      be deferred.  Since special requests may also be requeued requests,
2500  *      a successful return doesn't guarantee the device will be 
2501  *      totally quiescent.
2502  *
2503  *      Must be called with user context, may sleep.
2504  *
2505  *      Returns zero if unsuccessful or an error if not.
2506  */
2507 int
2508 scsi_device_quiesce(struct scsi_device *sdev)
2509 {
2510         int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2511         if (err)
2512                 return err;
2513
2514         scsi_run_queue(sdev->request_queue);
2515         while (sdev->device_busy) {
2516                 msleep_interruptible(200);
2517                 scsi_run_queue(sdev->request_queue);
2518         }
2519         return 0;
2520 }
2521 EXPORT_SYMBOL(scsi_device_quiesce);
2522
2523 /**
2524  *      scsi_device_resume - Restart user issued commands to a quiesced device.
2525  *      @sdev:  scsi device to resume.
2526  *
2527  *      Moves the device from quiesced back to running and restarts the
2528  *      queues.
2529  *
2530  *      Must be called with user context, may sleep.
2531  */
2532 void
2533 scsi_device_resume(struct scsi_device *sdev)
2534 {
2535         if(scsi_device_set_state(sdev, SDEV_RUNNING))
2536                 return;
2537         scsi_run_queue(sdev->request_queue);
2538 }
2539 EXPORT_SYMBOL(scsi_device_resume);
2540
2541 static void
2542 device_quiesce_fn(struct scsi_device *sdev, void *data)
2543 {
2544         scsi_device_quiesce(sdev);
2545 }
2546
2547 void
2548 scsi_target_quiesce(struct scsi_target *starget)
2549 {
2550         starget_for_each_device(starget, NULL, device_quiesce_fn);
2551 }
2552 EXPORT_SYMBOL(scsi_target_quiesce);
2553
2554 static void
2555 device_resume_fn(struct scsi_device *sdev, void *data)
2556 {
2557         scsi_device_resume(sdev);
2558 }
2559
2560 void
2561 scsi_target_resume(struct scsi_target *starget)
2562 {
2563         starget_for_each_device(starget, NULL, device_resume_fn);
2564 }
2565 EXPORT_SYMBOL(scsi_target_resume);
2566
2567 /**
2568  * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2569  * @sdev:       device to block
2570  *
2571  * Block request made by scsi lld's to temporarily stop all
2572  * scsi commands on the specified device.  Called from interrupt
2573  * or normal process context.
2574  *
2575  * Returns zero if successful or error if not
2576  *
2577  * Notes:       
2578  *      This routine transitions the device to the SDEV_BLOCK state
2579  *      (which must be a legal transition).  When the device is in this
2580  *      state, all commands are deferred until the scsi lld reenables
2581  *      the device with scsi_device_unblock or device_block_tmo fires.
2582  *      This routine assumes the host_lock is held on entry.
2583  */
2584 int
2585 scsi_internal_device_block(struct scsi_device *sdev)
2586 {
2587         struct request_queue *q = sdev->request_queue;
2588         unsigned long flags;
2589         int err = 0;
2590
2591         err = scsi_device_set_state(sdev, SDEV_BLOCK);
2592         if (err) {
2593                 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2594
2595                 if (err)
2596                         return err;
2597         }
2598
2599         /* 
2600          * The device has transitioned to SDEV_BLOCK.  Stop the
2601          * block layer from calling the midlayer with this device's
2602          * request queue. 
2603          */
2604         spin_lock_irqsave(q->queue_lock, flags);
2605         blk_stop_queue(q);
2606         spin_unlock_irqrestore(q->queue_lock, flags);
2607
2608         return 0;
2609 }
2610 EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2611  
2612 /**
2613  * scsi_internal_device_unblock - resume a device after a block request
2614  * @sdev:       device to resume
2615  *
2616  * Called by scsi lld's or the midlayer to restart the device queue
2617  * for the previously suspended scsi device.  Called from interrupt or
2618  * normal process context.
2619  *
2620  * Returns zero if successful or error if not.
2621  *
2622  * Notes:       
2623  *      This routine transitions the device to the SDEV_RUNNING state
2624  *      (which must be a legal transition) allowing the midlayer to
2625  *      goose the queue for this device.  This routine assumes the 
2626  *      host_lock is held upon entry.
2627  */
2628 int
2629 scsi_internal_device_unblock(struct scsi_device *sdev)
2630 {
2631         struct request_queue *q = sdev->request_queue; 
2632         int err;
2633         unsigned long flags;
2634         
2635         /* 
2636          * Try to transition the scsi device to SDEV_RUNNING
2637          * and goose the device queue if successful.  
2638          */
2639         err = scsi_device_set_state(sdev, SDEV_RUNNING);
2640         if (err) {
2641                 err = scsi_device_set_state(sdev, SDEV_CREATED);
2642
2643                 if (err)
2644                         return err;
2645         }
2646
2647         spin_lock_irqsave(q->queue_lock, flags);
2648         blk_start_queue(q);
2649         spin_unlock_irqrestore(q->queue_lock, flags);
2650
2651         return 0;
2652 }
2653 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2654
2655 static void
2656 device_block(struct scsi_device *sdev, void *data)
2657 {
2658         scsi_internal_device_block(sdev);
2659 }
2660
2661 static int
2662 target_block(struct device *dev, void *data)
2663 {
2664         if (scsi_is_target_device(dev))
2665                 starget_for_each_device(to_scsi_target(dev), NULL,
2666                                         device_block);
2667         return 0;
2668 }
2669
2670 void
2671 scsi_target_block(struct device *dev)
2672 {
2673         if (scsi_is_target_device(dev))
2674                 starget_for_each_device(to_scsi_target(dev), NULL,
2675                                         device_block);
2676         else
2677                 device_for_each_child(dev, NULL, target_block);
2678 }
2679 EXPORT_SYMBOL_GPL(scsi_target_block);
2680
2681 static void
2682 device_unblock(struct scsi_device *sdev, void *data)
2683 {
2684         scsi_internal_device_unblock(sdev);
2685 }
2686
2687 static int
2688 target_unblock(struct device *dev, void *data)
2689 {
2690         if (scsi_is_target_device(dev))
2691                 starget_for_each_device(to_scsi_target(dev), NULL,
2692                                         device_unblock);
2693         return 0;
2694 }
2695
2696 void
2697 scsi_target_unblock(struct device *dev)
2698 {
2699         if (scsi_is_target_device(dev))
2700                 starget_for_each_device(to_scsi_target(dev), NULL,
2701                                         device_unblock);
2702         else
2703                 device_for_each_child(dev, NULL, target_unblock);
2704 }
2705 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2706
2707 /**
2708  * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2709  * @sgl:        scatter-gather list
2710  * @sg_count:   number of segments in sg
2711  * @offset:     offset in bytes into sg, on return offset into the mapped area
2712  * @len:        bytes to map, on return number of bytes mapped
2713  *
2714  * Returns virtual address of the start of the mapped page
2715  */
2716 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2717                           size_t *offset, size_t *len)
2718 {
2719         int i;
2720         size_t sg_len = 0, len_complete = 0;
2721         struct scatterlist *sg;
2722         struct page *page;
2723
2724         WARN_ON(!irqs_disabled());
2725
2726         for_each_sg(sgl, sg, sg_count, i) {
2727                 len_complete = sg_len; /* Complete sg-entries */
2728                 sg_len += sg->length;
2729                 if (sg_len > *offset)
2730                         break;
2731         }
2732
2733         if (unlikely(i == sg_count)) {
2734                 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2735                         "elements %d\n",
2736                        __func__, sg_len, *offset, sg_count);
2737                 WARN_ON(1);
2738                 return NULL;
2739         }
2740
2741         /* Offset starting from the beginning of first page in this sg-entry */
2742         *offset = *offset - len_complete + sg->offset;
2743
2744         /* Assumption: contiguous pages can be accessed as "page + i" */
2745         page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2746         *offset &= ~PAGE_MASK;
2747
2748         /* Bytes in this sg-entry from *offset to the end of the page */
2749         sg_len = PAGE_SIZE - *offset;
2750         if (*len > sg_len)
2751                 *len = sg_len;
2752
2753         return kmap_atomic(page, KM_BIO_SRC_IRQ);
2754 }
2755 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2756
2757 /**
2758  * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2759  * @virt:       virtual address to be unmapped
2760  */
2761 void scsi_kunmap_atomic_sg(void *virt)
2762 {
2763         kunmap_atomic(virt, KM_BIO_SRC_IRQ);
2764 }
2765 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);