Root/fs/bio.c

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

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