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TOMOYO Linux Cross Reference
Linux/fs/bio.c

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  1 /*
  2  * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11  * GNU General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public Licens
 14  * along with this program; if not, write to the Free Software
 15  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 16  *
 17  */
 18 #include <linux/mm.h>
 19 #include <linux/swap.h>
 20 #include <linux/bio.h>
 21 #include <linux/blkdev.h>
 22 #include <linux/iocontext.h>
 23 #include <linux/slab.h>
 24 #include <linux/init.h>
 25 #include <linux/kernel.h>
 26 #include <linux/export.h>
 27 #include <linux/mempool.h>
 28 #include <linux/workqueue.h>
 29 #include <linux/cgroup.h>
 30 #include <scsi/sg.h>            /* for struct sg_iovec */
 31 
 32 #include <trace/events/block.h>
 33 
 34 /*
 35  * Test patch to inline a certain number of bi_io_vec's inside the bio
 36  * itself, to shrink a bio data allocation from two mempool calls to one
 37  */
 38 #define BIO_INLINE_VECS         4
 39 
 40 static mempool_t *bio_split_pool __read_mostly;
 41 
 42 /*
 43  * if you change this list, also change bvec_alloc or things will
 44  * break badly! cannot be bigger than what you can fit into an
 45  * unsigned short
 46  */
 47 #define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
 48 static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
 49         BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
 50 };
 51 #undef BV
 52 
 53 /*
 54  * fs_bio_set is the bio_set containing bio and iovec memory pools used by
 55  * IO code that does not need private memory pools.
 56  */
 57 struct bio_set *fs_bio_set;
 58 EXPORT_SYMBOL(fs_bio_set);
 59 
 60 /*
 61  * Our slab pool management
 62  */
 63 struct bio_slab {
 64         struct kmem_cache *slab;
 65         unsigned int slab_ref;
 66         unsigned int slab_size;
 67         char name[8];
 68 };
 69 static DEFINE_MUTEX(bio_slab_lock);
 70 static struct bio_slab *bio_slabs;
 71 static unsigned int bio_slab_nr, bio_slab_max;
 72 
 73 static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
 74 {
 75         unsigned int sz = sizeof(struct bio) + extra_size;
 76         struct kmem_cache *slab = NULL;
 77         struct bio_slab *bslab, *new_bio_slabs;
 78         unsigned int new_bio_slab_max;
 79         unsigned int i, entry = -1;
 80 
 81         mutex_lock(&bio_slab_lock);
 82 
 83         i = 0;
 84         while (i < bio_slab_nr) {
 85                 bslab = &bio_slabs[i];
 86 
 87                 if (!bslab->slab && entry == -1)
 88                         entry = i;
 89                 else if (bslab->slab_size == sz) {
 90                         slab = bslab->slab;
 91                         bslab->slab_ref++;
 92                         break;
 93                 }
 94                 i++;
 95         }
 96 
 97         if (slab)
 98                 goto out_unlock;
 99 
100         if (bio_slab_nr == bio_slab_max && entry == -1) {
101                 new_bio_slab_max = bio_slab_max << 1;
102                 new_bio_slabs = krealloc(bio_slabs,
103                                          new_bio_slab_max * sizeof(struct bio_slab),
104                                          GFP_KERNEL);
105                 if (!new_bio_slabs)
106                         goto out_unlock;
107                 bio_slab_max = new_bio_slab_max;
108                 bio_slabs = new_bio_slabs;
109         }
110         if (entry == -1)
111                 entry = bio_slab_nr++;
112 
113         bslab = &bio_slabs[entry];
114 
115         snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
116         slab = kmem_cache_create(bslab->name, sz, 0, SLAB_HWCACHE_ALIGN, NULL);
117         if (!slab)
118                 goto out_unlock;
119 
120         printk(KERN_INFO "bio: create slab <%s> at %d\n", bslab->name, entry);
121         bslab->slab = slab;
122         bslab->slab_ref = 1;
123         bslab->slab_size = sz;
124 out_unlock:
125         mutex_unlock(&bio_slab_lock);
126         return slab;
127 }
128 
129 static void bio_put_slab(struct bio_set *bs)
130 {
131         struct bio_slab *bslab = NULL;
132         unsigned int i;
133 
134         mutex_lock(&bio_slab_lock);
135 
136         for (i = 0; i < bio_slab_nr; i++) {
137                 if (bs->bio_slab == bio_slabs[i].slab) {
138                         bslab = &bio_slabs[i];
139                         break;
140                 }
141         }
142 
143         if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
144                 goto out;
145 
146         WARN_ON(!bslab->slab_ref);
147 
148         if (--bslab->slab_ref)
149                 goto out;
150 
151         kmem_cache_destroy(bslab->slab);
152         bslab->slab = NULL;
153 
154 out:
155         mutex_unlock(&bio_slab_lock);
156 }
157 
158 unsigned int bvec_nr_vecs(unsigned short idx)
159 {
160         return bvec_slabs[idx].nr_vecs;
161 }
162 
163 void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
164 {
165         BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
166 
167         if (idx == BIOVEC_MAX_IDX)
168                 mempool_free(bv, bs->bvec_pool);
169         else {
170                 struct biovec_slab *bvs = bvec_slabs + idx;
171 
172                 kmem_cache_free(bvs->slab, bv);
173         }
174 }
175 
176 struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
177                               struct bio_set *bs)
178 {
179         struct bio_vec *bvl;
180 
181         /*
182          * see comment near bvec_array define!
183          */
184         switch (nr) {
185         case 1:
186                 *idx = 0;
187                 break;
188         case 2 ... 4:
189                 *idx = 1;
190                 break;
191         case 5 ... 16:
192                 *idx = 2;
193                 break;
194         case 17 ... 64:
195                 *idx = 3;
196                 break;
197         case 65 ... 128:
198                 *idx = 4;
199                 break;
200         case 129 ... BIO_MAX_PAGES:
201                 *idx = 5;
202                 break;
203         default:
204                 return NULL;
205         }
206 
207         /*
208          * idx now points to the pool we want to allocate from. only the
209          * 1-vec entry pool is mempool backed.
210          */
211         if (*idx == BIOVEC_MAX_IDX) {
212 fallback:
213                 bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
214         } else {
215                 struct biovec_slab *bvs = bvec_slabs + *idx;
216                 gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
217 
218                 /*
219                  * Make this allocation restricted and don't dump info on
220                  * allocation failures, since we'll fallback to the mempool
221                  * in case of failure.
222                  */
223                 __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
224 
225                 /*
226                  * Try a slab allocation. If this fails and __GFP_WAIT
227                  * is set, retry with the 1-entry mempool
228                  */
229                 bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
230                 if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
231                         *idx = BIOVEC_MAX_IDX;
232                         goto fallback;
233                 }
234         }
235 
236         return bvl;
237 }
238 
239 static void __bio_free(struct bio *bio)
240 {
241         bio_disassociate_task(bio);
242 
243         if (bio_integrity(bio))
244                 bio_integrity_free(bio);
245 }
246 
247 static void bio_free(struct bio *bio)
248 {
249         struct bio_set *bs = bio->bi_pool;
250         void *p;
251 
252         __bio_free(bio);
253 
254         if (bs) {
255                 if (bio_has_allocated_vec(bio))
256                         bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
257 
258                 /*
259                  * If we have front padding, adjust the bio pointer before freeing
260                  */
261                 p = bio;
262                 p -= bs->front_pad;
263 
264                 mempool_free(p, bs->bio_pool);
265         } else {
266                 /* Bio was allocated by bio_kmalloc() */
267                 kfree(bio);
268         }
269 }
270 
271 void bio_init(struct bio *bio)
272 {
273         memset(bio, 0, sizeof(*bio));
274         bio->bi_flags = 1 << BIO_UPTODATE;
275         atomic_set(&bio->bi_cnt, 1);
276 }
277 EXPORT_SYMBOL(bio_init);
278 
279 /**
280  * bio_reset - reinitialize a bio
281  * @bio:        bio to reset
282  *
283  * Description:
284  *   After calling bio_reset(), @bio will be in the same state as a freshly
285  *   allocated bio returned bio bio_alloc_bioset() - the only fields that are
286  *   preserved are the ones that are initialized by bio_alloc_bioset(). See
287  *   comment in struct bio.
288  */
289 void bio_reset(struct bio *bio)
290 {
291         unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
292 
293         __bio_free(bio);
294 
295         memset(bio, 0, BIO_RESET_BYTES);
296         bio->bi_flags = flags|(1 << BIO_UPTODATE);
297 }
298 EXPORT_SYMBOL(bio_reset);
299 
300 /**
301  * bio_alloc_bioset - allocate a bio for I/O
302  * @gfp_mask:   the GFP_ mask given to the slab allocator
303  * @nr_iovecs:  number of iovecs to pre-allocate
304  * @bs:         the bio_set to allocate from.
305  *
306  * Description:
307  *   If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
308  *   backed by the @bs's mempool.
309  *
310  *   When @bs is not NULL, if %__GFP_WAIT is set then bio_alloc will always be
311  *   able to allocate a bio. This is due to the mempool guarantees. To make this
312  *   work, callers must never allocate more than 1 bio at a time from this pool.
313  *   Callers that need to allocate more than 1 bio must always submit the
314  *   previously allocated bio for IO before attempting to allocate a new one.
315  *   Failure to do so can cause deadlocks under memory pressure.
316  *
317  *   RETURNS:
318  *   Pointer to new bio on success, NULL on failure.
319  */
320 struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
321 {
322         unsigned front_pad;
323         unsigned inline_vecs;
324         unsigned long idx = BIO_POOL_NONE;
325         struct bio_vec *bvl = NULL;
326         struct bio *bio;
327         void *p;
328 
329         if (!bs) {
330                 if (nr_iovecs > UIO_MAXIOV)
331                         return NULL;
332 
333                 p = kmalloc(sizeof(struct bio) +
334                             nr_iovecs * sizeof(struct bio_vec),
335                             gfp_mask);
336                 front_pad = 0;
337                 inline_vecs = nr_iovecs;
338         } else {
339                 p = mempool_alloc(bs->bio_pool, gfp_mask);
340                 front_pad = bs->front_pad;
341                 inline_vecs = BIO_INLINE_VECS;
342         }
343 
344         if (unlikely(!p))
345                 return NULL;
346 
347         bio = p + front_pad;
348         bio_init(bio);
349 
350         if (nr_iovecs > inline_vecs) {
351                 bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
352                 if (unlikely(!bvl))
353                         goto err_free;
354         } else if (nr_iovecs) {
355                 bvl = bio->bi_inline_vecs;
356         }
357 
358         bio->bi_pool = bs;
359         bio->bi_flags |= idx << BIO_POOL_OFFSET;
360         bio->bi_max_vecs = nr_iovecs;
361         bio->bi_io_vec = bvl;
362         return bio;
363 
364 err_free:
365         mempool_free(p, bs->bio_pool);
366         return NULL;
367 }
368 EXPORT_SYMBOL(bio_alloc_bioset);
369 
370 void zero_fill_bio(struct bio *bio)
371 {
372         unsigned long flags;
373         struct bio_vec *bv;
374         int i;
375 
376         bio_for_each_segment(bv, bio, i) {
377                 char *data = bvec_kmap_irq(bv, &flags);
378                 memset(data, 0, bv->bv_len);
379                 flush_dcache_page(bv->bv_page);
380                 bvec_kunmap_irq(data, &flags);
381         }
382 }
383 EXPORT_SYMBOL(zero_fill_bio);
384 
385 /**
386  * bio_put - release a reference to a bio
387  * @bio:   bio to release reference to
388  *
389  * Description:
390  *   Put a reference to a &struct bio, either one you have gotten with
391  *   bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
392  **/
393 void bio_put(struct bio *bio)
394 {
395         BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
396 
397         /*
398          * last put frees it
399          */
400         if (atomic_dec_and_test(&bio->bi_cnt))
401                 bio_free(bio);
402 }
403 EXPORT_SYMBOL(bio_put);
404 
405 inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
406 {
407         if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
408                 blk_recount_segments(q, bio);
409 
410         return bio->bi_phys_segments;
411 }
412 EXPORT_SYMBOL(bio_phys_segments);
413 
414 /**
415  *      __bio_clone     -       clone a bio
416  *      @bio: destination bio
417  *      @bio_src: bio to clone
418  *
419  *      Clone a &bio. Caller will own the returned bio, but not
420  *      the actual data it points to. Reference count of returned
421  *      bio will be one.
422  */
423 void __bio_clone(struct bio *bio, struct bio *bio_src)
424 {
425         memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
426                 bio_src->bi_max_vecs * sizeof(struct bio_vec));
427 
428         /*
429          * most users will be overriding ->bi_bdev with a new target,
430          * so we don't set nor calculate new physical/hw segment counts here
431          */
432         bio->bi_sector = bio_src->bi_sector;
433         bio->bi_bdev = bio_src->bi_bdev;
434         bio->bi_flags |= 1 << BIO_CLONED;
435         bio->bi_rw = bio_src->bi_rw;
436         bio->bi_vcnt = bio_src->bi_vcnt;
437         bio->bi_size = bio_src->bi_size;
438         bio->bi_idx = bio_src->bi_idx;
439 }
440 EXPORT_SYMBOL(__bio_clone);
441 
442 /**
443  *      bio_clone_bioset -      clone a bio
444  *      @bio: bio to clone
445  *      @gfp_mask: allocation priority
446  *      @bs: bio_set to allocate from
447  *
448  *      Like __bio_clone, only also allocates the returned bio
449  */
450 struct bio *bio_clone_bioset(struct bio *bio, gfp_t gfp_mask,
451                              struct bio_set *bs)
452 {
453         struct bio *b;
454 
455         b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, bs);
456         if (!b)
457                 return NULL;
458 
459         __bio_clone(b, bio);
460 
461         if (bio_integrity(bio)) {
462                 int ret;
463 
464                 ret = bio_integrity_clone(b, bio, gfp_mask);
465 
466                 if (ret < 0) {
467                         bio_put(b);
468                         return NULL;
469                 }
470         }
471 
472         return b;
473 }
474 EXPORT_SYMBOL(bio_clone_bioset);
475 
476 /**
477  *      bio_get_nr_vecs         - return approx number of vecs
478  *      @bdev:  I/O target
479  *
480  *      Return the approximate number of pages we can send to this target.
481  *      There's no guarantee that you will be able to fit this number of pages
482  *      into a bio, it does not account for dynamic restrictions that vary
483  *      on offset.
484  */
485 int bio_get_nr_vecs(struct block_device *bdev)
486 {
487         struct request_queue *q = bdev_get_queue(bdev);
488         int nr_pages;
489 
490         nr_pages = min_t(unsigned,
491                      queue_max_segments(q),
492                      queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
493 
494         return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
495 
496 }
497 EXPORT_SYMBOL(bio_get_nr_vecs);
498 
499 static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
500                           *page, unsigned int len, unsigned int offset,
501                           unsigned short max_sectors)
502 {
503         int retried_segments = 0;
504         struct bio_vec *bvec;
505 
506         /*
507          * cloned bio must not modify vec list
508          */
509         if (unlikely(bio_flagged(bio, BIO_CLONED)))
510                 return 0;
511 
512         if (((bio->bi_size + len) >> 9) > max_sectors)
513                 return 0;
514 
515         /*
516          * For filesystems with a blocksize smaller than the pagesize
517          * we will often be called with the same page as last time and
518          * a consecutive offset.  Optimize this special case.
519          */
520         if (bio->bi_vcnt > 0) {
521                 struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
522 
523                 if (page == prev->bv_page &&
524                     offset == prev->bv_offset + prev->bv_len) {
525                         unsigned int prev_bv_len = prev->bv_len;
526                         prev->bv_len += len;
527 
528                         if (q->merge_bvec_fn) {
529                                 struct bvec_merge_data bvm = {
530                                         /* prev_bvec is already charged in
531                                            bi_size, discharge it in order to
532                                            simulate merging updated prev_bvec
533                                            as new bvec. */
534                                         .bi_bdev = bio->bi_bdev,
535                                         .bi_sector = bio->bi_sector,
536                                         .bi_size = bio->bi_size - prev_bv_len,
537                                         .bi_rw = bio->bi_rw,
538                                 };
539 
540                                 if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
541                                         prev->bv_len -= len;
542                                         return 0;
543                                 }
544                         }
545 
546                         goto done;
547                 }
548         }
549 
550         if (bio->bi_vcnt >= bio->bi_max_vecs)
551                 return 0;
552 
553         /*
554          * we might lose a segment or two here, but rather that than
555          * make this too complex.
556          */
557 
558         while (bio->bi_phys_segments >= queue_max_segments(q)) {
559 
560                 if (retried_segments)
561                         return 0;
562 
563                 retried_segments = 1;
564                 blk_recount_segments(q, bio);
565         }
566 
567         /*
568          * setup the new entry, we might clear it again later if we
569          * cannot add the page
570          */
571         bvec = &bio->bi_io_vec[bio->bi_vcnt];
572         bvec->bv_page = page;
573         bvec->bv_len = len;
574         bvec->bv_offset = offset;
575 
576         /*
577          * if queue has other restrictions (eg varying max sector size
578          * depending on offset), it can specify a merge_bvec_fn in the
579          * queue to get further control
580          */
581         if (q->merge_bvec_fn) {
582                 struct bvec_merge_data bvm = {
583                         .bi_bdev = bio->bi_bdev,
584                         .bi_sector = bio->bi_sector,
585                         .bi_size = bio->bi_size,
586                         .bi_rw = bio->bi_rw,
587                 };
588 
589                 /*
590                  * merge_bvec_fn() returns number of bytes it can accept
591                  * at this offset
592                  */
593                 if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
594                         bvec->bv_page = NULL;
595                         bvec->bv_len = 0;
596                         bvec->bv_offset = 0;
597                         return 0;
598                 }
599         }
600 
601         /* If we may be able to merge these biovecs, force a recount */
602         if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
603                 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
604 
605         bio->bi_vcnt++;
606         bio->bi_phys_segments++;
607  done:
608         bio->bi_size += len;
609         return len;
610 }
611 
612 /**
613  *      bio_add_pc_page -       attempt to add page to bio
614  *      @q: the target queue
615  *      @bio: destination bio
616  *      @page: page to add
617  *      @len: vec entry length
618  *      @offset: vec entry offset
619  *
620  *      Attempt to add a page to the bio_vec maplist. This can fail for a
621  *      number of reasons, such as the bio being full or target block device
622  *      limitations. The target block device must allow bio's up to PAGE_SIZE,
623  *      so it is always possible to add a single page to an empty bio.
624  *
625  *      This should only be used by REQ_PC bios.
626  */
627 int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
628                     unsigned int len, unsigned int offset)
629 {
630         return __bio_add_page(q, bio, page, len, offset,
631                               queue_max_hw_sectors(q));
632 }
633 EXPORT_SYMBOL(bio_add_pc_page);
634 
635 /**
636  *      bio_add_page    -       attempt to add page to bio
637  *      @bio: destination bio
638  *      @page: page to add
639  *      @len: vec entry length
640  *      @offset: vec entry offset
641  *
642  *      Attempt to add a page to the bio_vec maplist. This can fail for a
643  *      number of reasons, such as the bio being full or target block device
644  *      limitations. The target block device must allow bio's up to PAGE_SIZE,
645  *      so it is always possible to add a single page to an empty bio.
646  */
647 int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
648                  unsigned int offset)
649 {
650         struct request_queue *q = bdev_get_queue(bio->bi_bdev);
651         return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
652 }
653 EXPORT_SYMBOL(bio_add_page);
654 
655 struct bio_map_data {
656         struct bio_vec *iovecs;
657         struct sg_iovec *sgvecs;
658         int nr_sgvecs;
659         int is_our_pages;
660 };
661 
662 static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
663                              struct sg_iovec *iov, int iov_count,
664                              int is_our_pages)
665 {
666         memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
667         memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
668         bmd->nr_sgvecs = iov_count;
669         bmd->is_our_pages = is_our_pages;
670         bio->bi_private = bmd;
671 }
672 
673 static void bio_free_map_data(struct bio_map_data *bmd)
674 {
675         kfree(bmd->iovecs);
676         kfree(bmd->sgvecs);
677         kfree(bmd);
678 }
679 
680 static struct bio_map_data *bio_alloc_map_data(int nr_segs,
681                                                unsigned int iov_count,
682                                                gfp_t gfp_mask)
683 {
684         struct bio_map_data *bmd;
685 
686         if (iov_count > UIO_MAXIOV)
687                 return NULL;
688 
689         bmd = kmalloc(sizeof(*bmd), gfp_mask);
690         if (!bmd)
691                 return NULL;
692 
693         bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
694         if (!bmd->iovecs) {
695                 kfree(bmd);
696                 return NULL;
697         }
698 
699         bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
700         if (bmd->sgvecs)
701                 return bmd;
702 
703         kfree(bmd->iovecs);
704         kfree(bmd);
705         return NULL;
706 }
707 
708 static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
709                           struct sg_iovec *iov, int iov_count,
710                           int to_user, int from_user, int do_free_page)
711 {
712         int ret = 0, i;
713         struct bio_vec *bvec;
714         int iov_idx = 0;
715         unsigned int iov_off = 0;
716 
717         __bio_for_each_segment(bvec, bio, i, 0) {
718                 char *bv_addr = page_address(bvec->bv_page);
719                 unsigned int bv_len = iovecs[i].bv_len;
720 
721                 while (bv_len && iov_idx < iov_count) {
722                         unsigned int bytes;
723                         char __user *iov_addr;
724 
725                         bytes = min_t(unsigned int,
726                                       iov[iov_idx].iov_len - iov_off, bv_len);
727                         iov_addr = iov[iov_idx].iov_base + iov_off;
728 
729                         if (!ret) {
730                                 if (to_user)
731                                         ret = copy_to_user(iov_addr, bv_addr,
732                                                            bytes);
733 
734                                 if (from_user)
735                                         ret = copy_from_user(bv_addr, iov_addr,
736                                                              bytes);
737 
738                                 if (ret)
739                                         ret = -EFAULT;
740                         }
741 
742                         bv_len -= bytes;
743                         bv_addr += bytes;
744                         iov_addr += bytes;
745                         iov_off += bytes;
746 
747                         if (iov[iov_idx].iov_len == iov_off) {
748                                 iov_idx++;
749                                 iov_off = 0;
750                         }
751                 }
752 
753                 if (do_free_page)
754                         __free_page(bvec->bv_page);
755         }
756 
757         return ret;
758 }
759 
760 /**
761  *      bio_uncopy_user -       finish previously mapped bio
762  *      @bio: bio being terminated
763  *
764  *      Free pages allocated from bio_copy_user() and write back data
765  *      to user space in case of a read.
766  */
767 int bio_uncopy_user(struct bio *bio)
768 {
769         struct bio_map_data *bmd = bio->bi_private;
770         int ret = 0;
771 
772         if (!bio_flagged(bio, BIO_NULL_MAPPED))
773                 ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
774                                      bmd->nr_sgvecs, bio_data_dir(bio) == READ,
775                                      0, bmd->is_our_pages);
776         bio_free_map_data(bmd);
777         bio_put(bio);
778         return ret;
779 }
780 EXPORT_SYMBOL(bio_uncopy_user);
781 
782 /**
783  *      bio_copy_user_iov       -       copy user data to bio
784  *      @q: destination block queue
785  *      @map_data: pointer to the rq_map_data holding pages (if necessary)
786  *      @iov:   the iovec.
787  *      @iov_count: number of elements in the iovec
788  *      @write_to_vm: bool indicating writing to pages or not
789  *      @gfp_mask: memory allocation flags
790  *
791  *      Prepares and returns a bio for indirect user io, bouncing data
792  *      to/from kernel pages as necessary. Must be paired with
793  *      call bio_uncopy_user() on io completion.
794  */
795 struct bio *bio_copy_user_iov(struct request_queue *q,
796                               struct rq_map_data *map_data,
797                               struct sg_iovec *iov, int iov_count,
798                               int write_to_vm, gfp_t gfp_mask)
799 {
800         struct bio_map_data *bmd;
801         struct bio_vec *bvec;
802         struct page *page;
803         struct bio *bio;
804         int i, ret;
805         int nr_pages = 0;
806         unsigned int len = 0;
807         unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
808 
809         for (i = 0; i < iov_count; i++) {
810                 unsigned long uaddr;
811                 unsigned long end;
812                 unsigned long start;
813 
814                 uaddr = (unsigned long)iov[i].iov_base;
815                 end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
816                 start = uaddr >> PAGE_SHIFT;
817 
818                 /*
819                  * Overflow, abort
820                  */
821                 if (end < start)
822                         return ERR_PTR(-EINVAL);
823 
824                 nr_pages += end - start;
825                 len += iov[i].iov_len;
826         }
827 
828         if (offset)
829                 nr_pages++;
830 
831         bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
832         if (!bmd)
833                 return ERR_PTR(-ENOMEM);
834 
835         ret = -ENOMEM;
836         bio = bio_kmalloc(gfp_mask, nr_pages);
837         if (!bio)
838                 goto out_bmd;
839 
840         if (!write_to_vm)
841                 bio->bi_rw |= REQ_WRITE;
842 
843         ret = 0;
844 
845         if (map_data) {
846                 nr_pages = 1 << map_data->page_order;
847                 i = map_data->offset / PAGE_SIZE;
848         }
849         while (len) {
850                 unsigned int bytes = PAGE_SIZE;
851 
852                 bytes -= offset;
853 
854                 if (bytes > len)
855                         bytes = len;
856 
857                 if (map_data) {
858                         if (i == map_data->nr_entries * nr_pages) {
859                                 ret = -ENOMEM;
860                                 break;
861                         }
862 
863                         page = map_data->pages[i / nr_pages];
864                         page += (i % nr_pages);
865 
866                         i++;
867                 } else {
868                         page = alloc_page(q->bounce_gfp | gfp_mask);
869                         if (!page) {
870                                 ret = -ENOMEM;
871                                 break;
872                         }
873                 }
874 
875                 if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
876                         break;
877 
878                 len -= bytes;
879                 offset = 0;
880         }
881 
882         if (ret)
883                 goto cleanup;
884 
885         /*
886          * success
887          */
888         if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
889             (map_data && map_data->from_user)) {
890                 ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 1, 0);
891                 if (ret)
892                         goto cleanup;
893         }
894 
895         bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
896         return bio;
897 cleanup:
898         if (!map_data)
899                 bio_for_each_segment(bvec, bio, i)
900                         __free_page(bvec->bv_page);
901 
902         bio_put(bio);
903 out_bmd:
904         bio_free_map_data(bmd);
905         return ERR_PTR(ret);
906 }
907 
908 /**
909  *      bio_copy_user   -       copy user data to bio
910  *      @q: destination block queue
911  *      @map_data: pointer to the rq_map_data holding pages (if necessary)
912  *      @uaddr: start of user address
913  *      @len: length in bytes
914  *      @write_to_vm: bool indicating writing to pages or not
915  *      @gfp_mask: memory allocation flags
916  *
917  *      Prepares and returns a bio for indirect user io, bouncing data
918  *      to/from kernel pages as necessary. Must be paired with
919  *      call bio_uncopy_user() on io completion.
920  */
921 struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
922                           unsigned long uaddr, unsigned int len,
923                           int write_to_vm, gfp_t gfp_mask)
924 {
925         struct sg_iovec iov;
926 
927         iov.iov_base = (void __user *)uaddr;
928         iov.iov_len = len;
929 
930         return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
931 }
932 EXPORT_SYMBOL(bio_copy_user);
933 
934 static struct bio *__bio_map_user_iov(struct request_queue *q,
935                                       struct block_device *bdev,
936                                       struct sg_iovec *iov, int iov_count,
937                                       int write_to_vm, gfp_t gfp_mask)
938 {
939         int i, j;
940         int nr_pages = 0;
941         struct page **pages;
942         struct bio *bio;
943         int cur_page = 0;
944         int ret, offset;
945 
946         for (i = 0; i < iov_count; i++) {
947                 unsigned long uaddr = (unsigned long)iov[i].iov_base;
948                 unsigned long len = iov[i].iov_len;
949                 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
950                 unsigned long start = uaddr >> PAGE_SHIFT;
951 
952                 /*
953                  * Overflow, abort
954                  */
955                 if (end < start)
956                         return ERR_PTR(-EINVAL);
957 
958                 nr_pages += end - start;
959                 /*
960                  * buffer must be aligned to at least hardsector size for now
961                  */
962                 if (uaddr & queue_dma_alignment(q))
963                         return ERR_PTR(-EINVAL);
964         }
965 
966         if (!nr_pages)
967                 return ERR_PTR(-EINVAL);
968 
969         bio = bio_kmalloc(gfp_mask, nr_pages);
970         if (!bio)
971                 return ERR_PTR(-ENOMEM);
972 
973         ret = -ENOMEM;
974         pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
975         if (!pages)
976                 goto out;
977 
978         for (i = 0; i < iov_count; i++) {
979                 unsigned long uaddr = (unsigned long)iov[i].iov_base;
980                 unsigned long len = iov[i].iov_len;
981                 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
982                 unsigned long start = uaddr >> PAGE_SHIFT;
983                 const int local_nr_pages = end - start;
984                 const int page_limit = cur_page + local_nr_pages;
985 
986                 ret = get_user_pages_fast(uaddr, local_nr_pages,
987                                 write_to_vm, &pages[cur_page]);
988                 if (ret < local_nr_pages) {
989                         ret = -EFAULT;
990                         goto out_unmap;
991                 }
992 
993                 offset = uaddr & ~PAGE_MASK;
994                 for (j = cur_page; j < page_limit; j++) {
995                         unsigned int bytes = PAGE_SIZE - offset;
996 
997                         if (len <= 0)
998                                 break;
999                         
1000                         if (bytes > len)
1001                                 bytes = len;
1002 
1003                         /*
1004                          * sorry...
1005                          */
1006                         if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
1007                                             bytes)
1008                                 break;
1009 
1010                         len -= bytes;
1011                         offset = 0;
1012                 }
1013 
1014                 cur_page = j;
1015                 /*
1016                  * release the pages we didn't map into the bio, if any
1017                  */
1018                 while (j < page_limit)
1019                         page_cache_release(pages[j++]);
1020         }
1021 
1022         kfree(pages);
1023 
1024         /*
1025          * set data direction, and check if mapped pages need bouncing
1026          */
1027         if (!write_to_vm)
1028                 bio->bi_rw |= REQ_WRITE;
1029 
1030         bio->bi_bdev = bdev;
1031         bio->bi_flags |= (1 << BIO_USER_MAPPED);
1032         return bio;
1033 
1034  out_unmap:
1035         for (i = 0; i < nr_pages; i++) {
1036                 if(!pages[i])
1037                         break;
1038                 page_cache_release(pages[i]);
1039         }
1040  out:
1041         kfree(pages);
1042         bio_put(bio);
1043         return ERR_PTR(ret);
1044 }
1045 
1046 /**
1047  *      bio_map_user    -       map user address into bio
1048  *      @q: the struct request_queue for the bio
1049  *      @bdev: destination block device
1050  *      @uaddr: start of user address
1051  *      @len: length in bytes
1052  *      @write_to_vm: bool indicating writing to pages or not
1053  *      @gfp_mask: memory allocation flags
1054  *
1055  *      Map the user space address into a bio suitable for io to a block
1056  *      device. Returns an error pointer in case of error.
1057  */
1058 struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
1059                          unsigned long uaddr, unsigned int len, int write_to_vm,
1060                          gfp_t gfp_mask)
1061 {
1062         struct sg_iovec iov;
1063 
1064         iov.iov_base = (void __user *)uaddr;
1065         iov.iov_len = len;
1066 
1067         return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
1068 }
1069 EXPORT_SYMBOL(bio_map_user);
1070 
1071 /**
1072  *      bio_map_user_iov - map user sg_iovec table into bio
1073  *      @q: the struct request_queue for the bio
1074  *      @bdev: destination block device
1075  *      @iov:   the iovec.
1076  *      @iov_count: number of elements in the iovec
1077  *      @write_to_vm: bool indicating writing to pages or not
1078  *      @gfp_mask: memory allocation flags
1079  *
1080  *      Map the user space address into a bio suitable for io to a block
1081  *      device. Returns an error pointer in case of error.
1082  */
1083 struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
1084                              struct sg_iovec *iov, int iov_count,
1085                              int write_to_vm, gfp_t gfp_mask)
1086 {
1087         struct bio *bio;
1088 
1089         bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
1090                                  gfp_mask);
1091         if (IS_ERR(bio))
1092                 return bio;
1093 
1094         /*
1095          * subtle -- if __bio_map_user() ended up bouncing a bio,
1096          * it would normally disappear when its bi_end_io is run.
1097          * however, we need it for the unmap, so grab an extra
1098          * reference to it
1099          */
1100         bio_get(bio);
1101 
1102         return bio;
1103 }
1104 
1105 static void __bio_unmap_user(struct bio *bio)
1106 {
1107         struct bio_vec *bvec;
1108         int i;
1109 
1110         /*
1111          * make sure we dirty pages we wrote to
1112          */
1113         __bio_for_each_segment(bvec, bio, i, 0) {
1114                 if (bio_data_dir(bio) == READ)
1115                         set_page_dirty_lock(bvec->bv_page);
1116 
1117                 page_cache_release(bvec->bv_page);
1118         }
1119 
1120         bio_put(bio);
1121 }
1122 
1123 /**
1124  *      bio_unmap_user  -       unmap a bio
1125  *      @bio:           the bio being unmapped
1126  *
1127  *      Unmap a bio previously mapped by bio_map_user(). Must be called with
1128  *      a process context.
1129  *
1130  *      bio_unmap_user() may sleep.
1131  */
1132 void bio_unmap_user(struct bio *bio)
1133 {
1134         __bio_unmap_user(bio);
1135         bio_put(bio);
1136 }
1137 EXPORT_SYMBOL(bio_unmap_user);
1138 
1139 static void bio_map_kern_endio(struct bio *bio, int err)
1140 {
1141         bio_put(bio);
1142 }
1143 
1144 static struct bio *__bio_map_kern(struct request_queue *q, void *data,
1145                                   unsigned int len, gfp_t gfp_mask)
1146 {
1147         unsigned long kaddr = (unsigned long)data;
1148         unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1149         unsigned long start = kaddr >> PAGE_SHIFT;
1150         const int nr_pages = end - start;
1151         int offset, i;
1152         struct bio *bio;
1153 
1154         bio = bio_kmalloc(gfp_mask, nr_pages);
1155         if (!bio)
1156                 return ERR_PTR(-ENOMEM);
1157 
1158         offset = offset_in_page(kaddr);
1159         for (i = 0; i < nr_pages; i++) {
1160                 unsigned int bytes = PAGE_SIZE - offset;
1161 
1162                 if (len <= 0)
1163                         break;
1164 
1165                 if (bytes > len)
1166                         bytes = len;
1167 
1168                 if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1169                                     offset) < bytes)
1170                         break;
1171 
1172                 data += bytes;
1173                 len -= bytes;
1174                 offset = 0;
1175         }
1176 
1177         bio->bi_end_io = bio_map_kern_endio;
1178         return bio;
1179 }
1180 
1181 /**
1182  *      bio_map_kern    -       map kernel address into bio
1183  *      @q: the struct request_queue for the bio
1184  *      @data: pointer to buffer to map
1185  *      @len: length in bytes
1186  *      @gfp_mask: allocation flags for bio allocation
1187  *
1188  *      Map the kernel address into a bio suitable for io to a block
1189  *      device. Returns an error pointer in case of error.
1190  */
1191 struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1192                          gfp_t gfp_mask)
1193 {
1194         struct bio *bio;
1195 
1196         bio = __bio_map_kern(q, data, len, gfp_mask);
1197         if (IS_ERR(bio))
1198                 return bio;
1199 
1200         if (bio->bi_size == len)
1201                 return bio;
1202 
1203         /*
1204          * Don't support partial mappings.
1205          */
1206         bio_put(bio);
1207         return ERR_PTR(-EINVAL);
1208 }
1209 EXPORT_SYMBOL(bio_map_kern);
1210 
1211 static void bio_copy_kern_endio(struct bio *bio, int err)
1212 {
1213         struct bio_vec *bvec;
1214         const int read = bio_data_dir(bio) == READ;
1215         struct bio_map_data *bmd = bio->bi_private;
1216         int i;
1217         char *p = bmd->sgvecs[0].iov_base;
1218 
1219         __bio_for_each_segment(bvec, bio, i, 0) {
1220                 char *addr = page_address(bvec->bv_page);
1221                 int len = bmd->iovecs[i].bv_len;
1222 
1223                 if (read)
1224                         memcpy(p, addr, len);
1225 
1226                 __free_page(bvec->bv_page);
1227                 p += len;
1228         }
1229 
1230         bio_free_map_data(bmd);
1231         bio_put(bio);
1232 }
1233 
1234 /**
1235  *      bio_copy_kern   -       copy kernel address into bio
1236  *      @q: the struct request_queue for the bio
1237  *      @data: pointer to buffer to copy
1238  *      @len: length in bytes
1239  *      @gfp_mask: allocation flags for bio and page allocation
1240  *      @reading: data direction is READ
1241  *
1242  *      copy the kernel address into a bio suitable for io to a block
1243  *      device. Returns an error pointer in case of error.
1244  */
1245 struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1246                           gfp_t gfp_mask, int reading)
1247 {
1248         struct bio *bio;
1249         struct bio_vec *bvec;
1250         int i;
1251 
1252         bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
1253         if (IS_ERR(bio))
1254                 return bio;
1255 
1256         if (!reading) {
1257                 void *p = data;
1258 
1259                 bio_for_each_segment(bvec, bio, i) {
1260                         char *addr = page_address(bvec->bv_page);
1261 
1262                         memcpy(addr, p, bvec->bv_len);
1263                         p += bvec->bv_len;
1264                 }
1265         }
1266 
1267         bio->bi_end_io = bio_copy_kern_endio;
1268 
1269         return bio;
1270 }
1271 EXPORT_SYMBOL(bio_copy_kern);
1272 
1273 /*
1274  * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1275  * for performing direct-IO in BIOs.
1276  *
1277  * The problem is that we cannot run set_page_dirty() from interrupt context
1278  * because the required locks are not interrupt-safe.  So what we can do is to
1279  * mark the pages dirty _before_ performing IO.  And in interrupt context,
1280  * check that the pages are still dirty.   If so, fine.  If not, redirty them
1281  * in process context.
1282  *
1283  * We special-case compound pages here: normally this means reads into hugetlb
1284  * pages.  The logic in here doesn't really work right for compound pages
1285  * because the VM does not uniformly chase down the head page in all cases.
1286  * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1287  * handle them at all.  So we skip compound pages here at an early stage.
1288  *
1289  * Note that this code is very hard to test under normal circumstances because
1290  * direct-io pins the pages with get_user_pages().  This makes
1291  * is_page_cache_freeable return false, and the VM will not clean the pages.
1292  * But other code (eg, flusher threads) could clean the pages if they are mapped
1293  * pagecache.
1294  *
1295  * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1296  * deferred bio dirtying paths.
1297  */
1298 
1299 /*
1300  * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1301  */
1302 void bio_set_pages_dirty(struct bio *bio)
1303 {
1304         struct bio_vec *bvec = bio->bi_io_vec;
1305         int i;
1306 
1307         for (i = 0; i < bio->bi_vcnt; i++) {
1308                 struct page *page = bvec[i].bv_page;
1309 
1310                 if (page && !PageCompound(page))
1311                         set_page_dirty_lock(page);
1312         }
1313 }
1314 
1315 static void bio_release_pages(struct bio *bio)
1316 {
1317         struct bio_vec *bvec = bio->bi_io_vec;
1318         int i;
1319 
1320         for (i = 0; i < bio->bi_vcnt; i++) {
1321                 struct page *page = bvec[i].bv_page;
1322 
1323                 if (page)
1324                         put_page(page);
1325         }
1326 }
1327 
1328 /*
1329  * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1330  * If they are, then fine.  If, however, some pages are clean then they must
1331  * have been written out during the direct-IO read.  So we take another ref on
1332  * the BIO and the offending pages and re-dirty the pages in process context.
1333  *
1334  * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1335  * here on.  It will run one page_cache_release() against each page and will
1336  * run one bio_put() against the BIO.
1337  */
1338 
1339 static void bio_dirty_fn(struct work_struct *work);
1340 
1341 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1342 static DEFINE_SPINLOCK(bio_dirty_lock);
1343 static struct bio *bio_dirty_list;
1344 
1345 /*
1346  * This runs in process context
1347  */
1348 static void bio_dirty_fn(struct work_struct *work)
1349 {
1350         unsigned long flags;
1351         struct bio *bio;
1352 
1353         spin_lock_irqsave(&bio_dirty_lock, flags);
1354         bio = bio_dirty_list;
1355         bio_dirty_list = NULL;
1356         spin_unlock_irqrestore(&bio_dirty_lock, flags);
1357 
1358         while (bio) {
1359                 struct bio *next = bio->bi_private;
1360 
1361                 bio_set_pages_dirty(bio);
1362                 bio_release_pages(bio);
1363                 bio_put(bio);
1364                 bio = next;
1365         }
1366 }
1367 
1368 void bio_check_pages_dirty(struct bio *bio)
1369 {
1370         struct bio_vec *bvec = bio->bi_io_vec;
1371         int nr_clean_pages = 0;
1372         int i;
1373 
1374         for (i = 0; i < bio->bi_vcnt; i++) {
1375                 struct page *page = bvec[i].bv_page;
1376 
1377                 if (PageDirty(page) || PageCompound(page)) {
1378                         page_cache_release(page);
1379                         bvec[i].bv_page = NULL;
1380                 } else {
1381                         nr_clean_pages++;
1382                 }
1383         }
1384 
1385         if (nr_clean_pages) {
1386                 unsigned long flags;
1387 
1388                 spin_lock_irqsave(&bio_dirty_lock, flags);
1389                 bio->bi_private = bio_dirty_list;
1390                 bio_dirty_list = bio;
1391                 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1392                 schedule_work(&bio_dirty_work);
1393         } else {
1394                 bio_put(bio);
1395         }
1396 }
1397 
1398 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1399 void bio_flush_dcache_pages(struct bio *bi)
1400 {
1401         int i;
1402         struct bio_vec *bvec;
1403 
1404         bio_for_each_segment(bvec, bi, i)
1405                 flush_dcache_page(bvec->bv_page);
1406 }
1407 EXPORT_SYMBOL(bio_flush_dcache_pages);
1408 #endif
1409 
1410 /**
1411  * bio_endio - end I/O on a bio
1412  * @bio:        bio
1413  * @error:      error, if any
1414  *
1415  * Description:
1416  *   bio_endio() will end I/O on the whole bio. bio_endio() is the
1417  *   preferred way to end I/O on a bio, it takes care of clearing
1418  *   BIO_UPTODATE on error. @error is 0 on success, and and one of the
1419  *   established -Exxxx (-EIO, for instance) error values in case
1420  *   something went wrong. No one should call bi_end_io() directly on a
1421  *   bio unless they own it and thus know that it has an end_io
1422  *   function.
1423  **/
1424 void bio_endio(struct bio *bio, int error)
1425 {
1426         if (error)
1427                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
1428         else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1429                 error = -EIO;
1430 
1431         if (bio->bi_end_io)
1432                 bio->bi_end_io(bio, error);
1433 }
1434 EXPORT_SYMBOL(bio_endio);
1435 
1436 void bio_pair_release(struct bio_pair *bp)
1437 {
1438         if (atomic_dec_and_test(&bp->cnt)) {
1439                 struct bio *master = bp->bio1.bi_private;
1440 
1441                 bio_endio(master, bp->error);
1442                 mempool_free(bp, bp->bio2.bi_private);
1443         }
1444 }
1445 EXPORT_SYMBOL(bio_pair_release);
1446 
1447 static void bio_pair_end_1(struct bio *bi, int err)
1448 {
1449         struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
1450 
1451         if (err)
1452                 bp->error = err;
1453 
1454         bio_pair_release(bp);
1455 }
1456 
1457 static void bio_pair_end_2(struct bio *bi, int err)
1458 {
1459         struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
1460 
1461         if (err)
1462                 bp->error = err;
1463 
1464         bio_pair_release(bp);
1465 }
1466 
1467 /*
1468  * split a bio - only worry about a bio with a single page in its iovec
1469  */
1470 struct bio_pair *bio_split(struct bio *bi, int first_sectors)
1471 {
1472         struct bio_pair *bp = mempool_alloc(bio_split_pool, GFP_NOIO);
1473 
1474         if (!bp)
1475                 return bp;
1476 
1477         trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
1478                                 bi->bi_sector + first_sectors);
1479 
1480         BUG_ON(bi->bi_vcnt != 1 && bi->bi_vcnt != 0);
1481         BUG_ON(bi->bi_idx != 0);
1482         atomic_set(&bp->cnt, 3);
1483         bp->error = 0;
1484         bp->bio1 = *bi;
1485         bp->bio2 = *bi;
1486         bp->bio2.bi_sector += first_sectors;
1487         bp->bio2.bi_size -= first_sectors << 9;
1488         bp->bio1.bi_size = first_sectors << 9;
1489 
1490         if (bi->bi_vcnt != 0) {
1491                 bp->bv1 = bi->bi_io_vec[0];
1492                 bp->bv2 = bi->bi_io_vec[0];
1493 
1494                 if (bio_is_rw(bi)) {
1495                         bp->bv2.bv_offset += first_sectors << 9;
1496                         bp->bv2.bv_len -= first_sectors << 9;
1497                         bp->bv1.bv_len = first_sectors << 9;
1498                 }
1499 
1500                 bp->bio1.bi_io_vec = &bp->bv1;
1501                 bp->bio2.bi_io_vec = &bp->bv2;
1502 
1503                 bp->bio1.bi_max_vecs = 1;
1504                 bp->bio2.bi_max_vecs = 1;
1505         }
1506 
1507         bp->bio1.bi_end_io = bio_pair_end_1;
1508         bp->bio2.bi_end_io = bio_pair_end_2;
1509 
1510         bp->bio1.bi_private = bi;
1511         bp->bio2.bi_private = bio_split_pool;
1512 
1513         if (bio_integrity(bi))
1514                 bio_integrity_split(bi, bp, first_sectors);
1515 
1516         return bp;
1517 }
1518 EXPORT_SYMBOL(bio_split);
1519 
1520 /**
1521  *      bio_sector_offset - Find hardware sector offset in bio
1522  *      @bio:           bio to inspect
1523  *      @index:         bio_vec index
1524  *      @offset:        offset in bv_page
1525  *
1526  *      Return the number of hardware sectors between beginning of bio
1527  *      and an end point indicated by a bio_vec index and an offset
1528  *      within that vector's page.
1529  */
1530 sector_t bio_sector_offset(struct bio *bio, unsigned short index,
1531                            unsigned int offset)
1532 {
1533         unsigned int sector_sz;
1534         struct bio_vec *bv;
1535         sector_t sectors;
1536         int i;
1537 
1538         sector_sz = queue_logical_block_size(bio->bi_bdev->bd_disk->queue);
1539         sectors = 0;
1540 
1541         if (index >= bio->bi_idx)
1542                 index = bio->bi_vcnt - 1;
1543 
1544         __bio_for_each_segment(bv, bio, i, 0) {
1545                 if (i == index) {
1546                         if (offset > bv->bv_offset)
1547                                 sectors += (offset - bv->bv_offset) / sector_sz;
1548                         break;
1549                 }
1550 
1551                 sectors += bv->bv_len / sector_sz;
1552         }
1553 
1554         return sectors;
1555 }
1556 EXPORT_SYMBOL(bio_sector_offset);
1557 
1558 /*
1559  * create memory pools for biovec's in a bio_set.
1560  * use the global biovec slabs created for general use.
1561  */
1562 static int biovec_create_pools(struct bio_set *bs, int pool_entries)
1563 {
1564         struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
1565 
1566         bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
1567         if (!bs->bvec_pool)
1568                 return -ENOMEM;
1569 
1570         return 0;
1571 }
1572 
1573 static void biovec_free_pools(struct bio_set *bs)
1574 {
1575         mempool_destroy(bs->bvec_pool);
1576 }
1577 
1578 void bioset_free(struct bio_set *bs)
1579 {
1580         if (bs->bio_pool)
1581                 mempool_destroy(bs->bio_pool);
1582 
1583         bioset_integrity_free(bs);
1584         biovec_free_pools(bs);
1585         bio_put_slab(bs);
1586 
1587         kfree(bs);
1588 }
1589 EXPORT_SYMBOL(bioset_free);
1590 
1591 /**
1592  * bioset_create  - Create a bio_set
1593  * @pool_size:  Number of bio and bio_vecs to cache in the mempool
1594  * @front_pad:  Number of bytes to allocate in front of the returned bio
1595  *
1596  * Description:
1597  *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1598  *    to ask for a number of bytes to be allocated in front of the bio.
1599  *    Front pad allocation is useful for embedding the bio inside
1600  *    another structure, to avoid allocating extra data to go with the bio.
1601  *    Note that the bio must be embedded at the END of that structure always,
1602  *    or things will break badly.
1603  */
1604 struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
1605 {
1606         unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1607         struct bio_set *bs;
1608 
1609         bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1610         if (!bs)
1611                 return NULL;
1612 
1613         bs->front_pad = front_pad;
1614 
1615         bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1616         if (!bs->bio_slab) {
1617                 kfree(bs);
1618                 return NULL;
1619         }
1620 
1621         bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
1622         if (!bs->bio_pool)
1623                 goto bad;
1624 
1625         if (!biovec_create_pools(bs, pool_size))
1626                 return bs;
1627 
1628 bad:
1629         bioset_free(bs);
1630         return NULL;
1631 }
1632 EXPORT_SYMBOL(bioset_create);
1633 
1634 #ifdef CONFIG_BLK_CGROUP
1635 /**
1636  * bio_associate_current - associate a bio with %current
1637  * @bio: target bio
1638  *
1639  * Associate @bio with %current if it hasn't been associated yet.  Block
1640  * layer will treat @bio as if it were issued by %current no matter which
1641  * task actually issues it.
1642  *
1643  * This function takes an extra reference of @task's io_context and blkcg
1644  * which will be put when @bio is released.  The caller must own @bio,
1645  * ensure %current->io_context exists, and is responsible for synchronizing
1646  * calls to this function.
1647  */
1648 int bio_associate_current(struct bio *bio)
1649 {
1650         struct io_context *ioc;
1651         struct cgroup_subsys_state *css;
1652 
1653         if (bio->bi_ioc)
1654                 return -EBUSY;
1655 
1656         ioc = current->io_context;
1657         if (!ioc)
1658                 return -ENOENT;
1659 
1660         /* acquire active ref on @ioc and associate */
1661         get_io_context_active(ioc);
1662         bio->bi_ioc = ioc;
1663 
1664         /* associate blkcg if exists */
1665         rcu_read_lock();
1666         css = task_subsys_state(current, blkio_subsys_id);
1667         if (css && css_tryget(css))
1668                 bio->bi_css = css;
1669         rcu_read_unlock();
1670 
1671         return 0;
1672 }
1673 
1674 /**
1675  * bio_disassociate_task - undo bio_associate_current()
1676  * @bio: target bio
1677  */
1678 void bio_disassociate_task(struct bio *bio)
1679 {
1680         if (bio->bi_ioc) {
1681                 put_io_context(bio->bi_ioc);
1682                 bio->bi_ioc = NULL;
1683         }
1684         if (bio->bi_css) {
1685                 css_put(bio->bi_css);
1686                 bio->bi_css = NULL;
1687         }
1688 }
1689 
1690 #endif /* CONFIG_BLK_CGROUP */
1691 
1692 static void __init biovec_init_slabs(void)
1693 {
1694         int i;
1695 
1696         for (i = 0; i < BIOVEC_NR_POOLS; i++) {
1697                 int size;
1698                 struct biovec_slab *bvs = bvec_slabs + i;
1699 
1700                 if (bvs->nr_vecs <= BIO_INLINE_VECS) {
1701                         bvs->slab = NULL;
1702                         continue;
1703                 }
1704 
1705                 size = bvs->nr_vecs * sizeof(struct bio_vec);
1706                 bvs->slab = kmem_cache_create(bvs->name, size, 0,
1707                                 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1708         }
1709 }
1710 
1711 static int __init init_bio(void)
1712 {
1713         bio_slab_max = 2;
1714         bio_slab_nr = 0;
1715         bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
1716         if (!bio_slabs)
1717                 panic("bio: can't allocate bios\n");
1718 
1719         bio_integrity_init();
1720         biovec_init_slabs();
1721 
1722         fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
1723         if (!fs_bio_set)
1724                 panic("bio: can't allocate bios\n");
1725 
1726         if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
1727                 panic("bio: can't create integrity pool\n");
1728 
1729         bio_split_pool = mempool_create_kmalloc_pool(BIO_SPLIT_ENTRIES,
1730                                                      sizeof(struct bio_pair));
1731         if (!bio_split_pool)
1732                 panic("bio: can't create split pool\n");
1733 
1734         return 0;
1735 }
1736 subsys_initcall(init_bio);
1737 

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