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

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