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        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}
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    bio = kmalloc(sizeof(struct bio) + nr_iovecs * sizeof(struct bio_vec),
374              gfp_mask);
375    if (unlikely(!bio))
376        return NULL;
377
378    bio_init(bio);
379    bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET;
380    bio->bi_max_vecs = nr_iovecs;
381    bio->bi_io_vec = bio->bi_inline_vecs;
382    bio->bi_destructor = bio_kmalloc_destructor;
383
384    return bio;
385}
386EXPORT_SYMBOL(bio_kmalloc);
387
388void zero_fill_bio(struct bio *bio)
389{
390    unsigned long flags;
391    struct bio_vec *bv;
392    int i;
393
394    bio_for_each_segment(bv, bio, i) {
395        char *data = bvec_kmap_irq(bv, &flags);
396        memset(data, 0, bv->bv_len);
397        flush_dcache_page(bv->bv_page);
398        bvec_kunmap_irq(data, &flags);
399    }
400}
401EXPORT_SYMBOL(zero_fill_bio);
402
403/**
404 * bio_put - release a reference to a bio
405 * @bio: bio to release reference to
406 *
407 * Description:
408 * Put a reference to a &struct bio, either one you have gotten with
409 * bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
410 **/
411void bio_put(struct bio *bio)
412{
413    BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
414
415    /*
416     * last put frees it
417     */
418    if (atomic_dec_and_test(&bio->bi_cnt)) {
419        bio->bi_next = NULL;
420        bio->bi_destructor(bio);
421    }
422}
423EXPORT_SYMBOL(bio_put);
424
425inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
426{
427    if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
428        blk_recount_segments(q, bio);
429
430    return bio->bi_phys_segments;
431}
432EXPORT_SYMBOL(bio_phys_segments);
433
434/**
435 * __bio_clone - clone a bio
436 * @bio: destination bio
437 * @bio_src: bio to clone
438 *
439 * Clone a &bio. Caller will own the returned bio, but not
440 * the actual data it points to. Reference count of returned
441 * bio will be one.
442 */
443void __bio_clone(struct bio *bio, struct bio *bio_src)
444{
445    memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
446        bio_src->bi_max_vecs * sizeof(struct bio_vec));
447
448    /*
449     * most users will be overriding ->bi_bdev with a new target,
450     * so we don't set nor calculate new physical/hw segment counts here
451     */
452    bio->bi_sector = bio_src->bi_sector;
453    bio->bi_bdev = bio_src->bi_bdev;
454    bio->bi_flags |= 1 << BIO_CLONED;
455    bio->bi_rw = bio_src->bi_rw;
456    bio->bi_vcnt = bio_src->bi_vcnt;
457    bio->bi_size = bio_src->bi_size;
458    bio->bi_idx = bio_src->bi_idx;
459}
460EXPORT_SYMBOL(__bio_clone);
461
462/**
463 * bio_clone - clone a bio
464 * @bio: bio to clone
465 * @gfp_mask: allocation priority
466 *
467 * Like __bio_clone, only also allocates the returned bio
468 */
469struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
470{
471    struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set);
472
473    if (!b)
474        return NULL;
475
476    b->bi_destructor = bio_fs_destructor;
477    __bio_clone(b, bio);
478
479    if (bio_integrity(bio)) {
480        int ret;
481
482        ret = bio_integrity_clone(b, bio, gfp_mask, fs_bio_set);
483
484        if (ret < 0) {
485            bio_put(b);
486            return NULL;
487        }
488    }
489
490    return b;
491}
492EXPORT_SYMBOL(bio_clone);
493
494/**
495 * bio_get_nr_vecs - return approx number of vecs
496 * @bdev: I/O target
497 *
498 * Return the approximate number of pages we can send to this target.
499 * There's no guarantee that you will be able to fit this number of pages
500 * into a bio, it does not account for dynamic restrictions that vary
501 * on offset.
502 */
503int bio_get_nr_vecs(struct block_device *bdev)
504{
505    struct request_queue *q = bdev_get_queue(bdev);
506    int nr_pages;
507
508    nr_pages = ((queue_max_sectors(q) << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
509    if (nr_pages > queue_max_segments(q))
510        nr_pages = queue_max_segments(q);
511
512    return nr_pages;
513}
514EXPORT_SYMBOL(bio_get_nr_vecs);
515
516static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
517              *page, unsigned int len, unsigned int offset,
518              unsigned short max_sectors)
519{
520    int retried_segments = 0;
521    struct bio_vec *bvec;
522
523    /*
524     * cloned bio must not modify vec list
525     */
526    if (unlikely(bio_flagged(bio, BIO_CLONED)))
527        return 0;
528
529    if (((bio->bi_size + len) >> 9) > max_sectors)
530        return 0;
531
532    /*
533     * For filesystems with a blocksize smaller than the pagesize
534     * we will often be called with the same page as last time and
535     * a consecutive offset. Optimize this special case.
536     */
537    if (bio->bi_vcnt > 0) {
538        struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
539
540        if (page == prev->bv_page &&
541            offset == prev->bv_offset + prev->bv_len) {
542            unsigned int prev_bv_len = prev->bv_len;
543            prev->bv_len += len;
544
545            if (q->merge_bvec_fn) {
546                struct bvec_merge_data bvm = {
547                    /* prev_bvec is already charged in
548                       bi_size, discharge it in order to
549                       simulate merging updated prev_bvec
550                       as new bvec. */
551                    .bi_bdev = bio->bi_bdev,
552                    .bi_sector = bio->bi_sector,
553                    .bi_size = bio->bi_size - prev_bv_len,
554                    .bi_rw = bio->bi_rw,
555                };
556
557                if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
558                    prev->bv_len -= len;
559                    return 0;
560                }
561            }
562
563            goto done;
564        }
565    }
566
567    if (bio->bi_vcnt >= bio->bi_max_vecs)
568        return 0;
569
570    /*
571     * we might lose a segment or two here, but rather that than
572     * make this too complex.
573     */
574
575    while (bio->bi_phys_segments >= queue_max_segments(q)) {
576
577        if (retried_segments)
578            return 0;
579
580        retried_segments = 1;
581        blk_recount_segments(q, bio);
582    }
583
584    /*
585     * setup the new entry, we might clear it again later if we
586     * cannot add the page
587     */
588    bvec = &bio->bi_io_vec[bio->bi_vcnt];
589    bvec->bv_page = page;
590    bvec->bv_len = len;
591    bvec->bv_offset = offset;
592
593    /*
594     * if queue has other restrictions (eg varying max sector size
595     * depending on offset), it can specify a merge_bvec_fn in the
596     * queue to get further control
597     */
598    if (q->merge_bvec_fn) {
599        struct bvec_merge_data bvm = {
600            .bi_bdev = bio->bi_bdev,
601            .bi_sector = bio->bi_sector,
602            .bi_size = bio->bi_size,
603            .bi_rw = bio->bi_rw,
604        };
605
606        /*
607         * merge_bvec_fn() returns number of bytes it can accept
608         * at this offset
609         */
610        if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
611            bvec->bv_page = NULL;
612            bvec->bv_len = 0;
613            bvec->bv_offset = 0;
614            return 0;
615        }
616    }
617
618    /* If we may be able to merge these biovecs, force a recount */
619    if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
620        bio->bi_flags &= ~(1 << BIO_SEG_VALID);
621
622    bio->bi_vcnt++;
623    bio->bi_phys_segments++;
624 done:
625    bio->bi_size += len;
626    return len;
627}
628
629/**
630 * bio_add_pc_page - attempt to add page to bio
631 * @q: the target queue
632 * @bio: destination bio
633 * @page: page to add
634 * @len: vec entry length
635 * @offset: vec entry offset
636 *
637 * Attempt to add a page to the bio_vec maplist. This can fail for a
638 * number of reasons, such as the bio being full or target block
639 * device limitations. The target block device must allow bio's
640 * smaller than PAGE_SIZE, so it is always possible to add a single
641 * page to an empty bio. This should only be used by REQ_PC bios.
642 */
643int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
644            unsigned int len, unsigned int offset)
645{
646    return __bio_add_page(q, bio, page, len, offset,
647                  queue_max_hw_sectors(q));
648}
649EXPORT_SYMBOL(bio_add_pc_page);
650
651/**
652 * bio_add_page - attempt to add page to bio
653 * @bio: destination bio
654 * @page: page to add
655 * @len: vec entry length
656 * @offset: vec entry offset
657 *
658 * Attempt to add a page to the bio_vec maplist. This can fail for a
659 * number of reasons, such as the bio being full or target block
660 * device limitations. The target block device must allow bio's
661 * smaller than PAGE_SIZE, so it is always possible to add a single
662 * page to an empty bio.
663 */
664int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
665         unsigned int offset)
666{
667    struct request_queue *q = bdev_get_queue(bio->bi_bdev);
668    return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
669}
670EXPORT_SYMBOL(bio_add_page);
671
672struct bio_map_data {
673    struct bio_vec *iovecs;
674    struct sg_iovec *sgvecs;
675    int nr_sgvecs;
676    int is_our_pages;
677};
678
679static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
680                 struct sg_iovec *iov, int iov_count,
681                 int is_our_pages)
682{
683    memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
684    memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
685    bmd->nr_sgvecs = iov_count;
686    bmd->is_our_pages = is_our_pages;
687    bio->bi_private = bmd;
688}
689
690static void bio_free_map_data(struct bio_map_data *bmd)
691{
692    kfree(bmd->iovecs);
693    kfree(bmd->sgvecs);
694    kfree(bmd);
695}
696
697static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
698                           gfp_t gfp_mask)
699{
700    struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);
701
702    if (!bmd)
703        return NULL;
704
705    bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
706    if (!bmd->iovecs) {
707        kfree(bmd);
708        return NULL;
709    }
710
711    bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
712    if (bmd->sgvecs)
713        return bmd;
714
715    kfree(bmd->iovecs);
716    kfree(bmd);
717    return NULL;
718}
719
720static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
721              struct sg_iovec *iov, int iov_count,
722              int to_user, int from_user, int do_free_page)
723{
724    int ret = 0, i;
725    struct bio_vec *bvec;
726    int iov_idx = 0;
727    unsigned int iov_off = 0;
728
729    __bio_for_each_segment(bvec, bio, i, 0) {
730        char *bv_addr = page_address(bvec->bv_page);
731        unsigned int bv_len = iovecs[i].bv_len;
732
733        while (bv_len && iov_idx < iov_count) {
734            unsigned int bytes;
735            char __user *iov_addr;
736
737            bytes = min_t(unsigned int,
738                      iov[iov_idx].iov_len - iov_off, bv_len);
739            iov_addr = iov[iov_idx].iov_base + iov_off;
740
741            if (!ret) {
742                if (to_user)
743                    ret = copy_to_user(iov_addr, bv_addr,
744                               bytes);
745
746                if (from_user)
747                    ret = copy_from_user(bv_addr, iov_addr,
748                                 bytes);
749
750                if (ret)
751                    ret = -EFAULT;
752            }
753
754            bv_len -= bytes;
755            bv_addr += bytes;
756            iov_addr += bytes;
757            iov_off += bytes;
758
759            if (iov[iov_idx].iov_len == iov_off) {
760                iov_idx++;
761                iov_off = 0;
762            }
763        }
764
765        if (do_free_page)
766            __free_page(bvec->bv_page);
767    }
768
769    return ret;
770}
771
772/**
773 * bio_uncopy_user - finish previously mapped bio
774 * @bio: bio being terminated
775 *
776 * Free pages allocated from bio_copy_user() and write back data
777 * to user space in case of a read.
778 */
779int bio_uncopy_user(struct bio *bio)
780{
781    struct bio_map_data *bmd = bio->bi_private;
782    int ret = 0;
783
784    if (!bio_flagged(bio, BIO_NULL_MAPPED))
785        ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
786                     bmd->nr_sgvecs, bio_data_dir(bio) == READ,
787                     0, bmd->is_our_pages);
788    bio_free_map_data(bmd);
789    bio_put(bio);
790    return ret;
791}
792EXPORT_SYMBOL(bio_uncopy_user);
793
794/**
795 * bio_copy_user_iov - copy user data to bio
796 * @q: destination block queue
797 * @map_data: pointer to the rq_map_data holding pages (if necessary)
798 * @iov: the iovec.
799 * @iov_count: number of elements in the iovec
800 * @write_to_vm: bool indicating writing to pages or not
801 * @gfp_mask: memory allocation flags
802 *
803 * Prepares and returns a bio for indirect user io, bouncing data
804 * to/from kernel pages as necessary. Must be paired with
805 * call bio_uncopy_user() on io completion.
806 */
807struct bio *bio_copy_user_iov(struct request_queue *q,
808                  struct rq_map_data *map_data,
809                  struct sg_iovec *iov, int iov_count,
810                  int write_to_vm, gfp_t gfp_mask)
811{
812    struct bio_map_data *bmd;
813    struct bio_vec *bvec;
814    struct page *page;
815    struct bio *bio;
816    int i, ret;
817    int nr_pages = 0;
818    unsigned int len = 0;
819    unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
820
821    for (i = 0; i < iov_count; i++) {
822        unsigned long uaddr;
823        unsigned long end;
824        unsigned long start;
825
826        uaddr = (unsigned long)iov[i].iov_base;
827        end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
828        start = uaddr >> PAGE_SHIFT;
829
830        nr_pages += end - start;
831        len += iov[i].iov_len;
832    }
833
834    if (offset)
835        nr_pages++;
836
837    bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
838    if (!bmd)
839        return ERR_PTR(-ENOMEM);
840
841    ret = -ENOMEM;
842    bio = bio_kmalloc(gfp_mask, nr_pages);
843    if (!bio)
844        goto out_bmd;
845
846    bio->bi_rw |= (!write_to_vm << BIO_RW);
847
848    ret = 0;
849
850    if (map_data) {
851        nr_pages = 1 << map_data->page_order;
852        i = map_data->offset / PAGE_SIZE;
853    }
854    while (len) {
855        unsigned int bytes = PAGE_SIZE;
856
857        bytes -= offset;
858
859        if (bytes > len)
860            bytes = len;
861
862        if (map_data) {
863            if (i == map_data->nr_entries * nr_pages) {
864                ret = -ENOMEM;
865                break;
866            }
867
868            page = map_data->pages[i / nr_pages];
869            page += (i % nr_pages);
870
871            i++;
872        } else {
873            page = alloc_page(q->bounce_gfp | gfp_mask);
874            if (!page) {
875                ret = -ENOMEM;
876                break;
877            }
878        }
879
880        if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
881            break;
882
883        len -= bytes;
884        offset = 0;
885    }
886
887    if (ret)
888        goto cleanup;
889
890    /*
891     * success
892     */
893    if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
894        (map_data && map_data->from_user)) {
895        ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 1, 0);
896        if (ret)
897            goto cleanup;
898    }
899
900    bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
901    return bio;
902cleanup:
903    if (!map_data)
904        bio_for_each_segment(bvec, bio, i)
905            __free_page(bvec->bv_page);
906
907    bio_put(bio);
908out_bmd:
909    bio_free_map_data(bmd);
910    return ERR_PTR(ret);
911}
912
913/**
914 * bio_copy_user - copy user data to bio
915 * @q: destination block queue
916 * @map_data: pointer to the rq_map_data holding pages (if necessary)
917 * @uaddr: start of user address
918 * @len: length in bytes
919 * @write_to_vm: bool indicating writing to pages or not
920 * @gfp_mask: memory allocation flags
921 *
922 * Prepares and returns a bio for indirect user io, bouncing data
923 * to/from kernel pages as necessary. Must be paired with
924 * call bio_uncopy_user() on io completion.
925 */
926struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
927              unsigned long uaddr, unsigned int len,
928              int write_to_vm, gfp_t gfp_mask)
929{
930    struct sg_iovec iov;
931
932    iov.iov_base = (void __user *)uaddr;
933    iov.iov_len = len;
934
935    return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
936}
937EXPORT_SYMBOL(bio_copy_user);
938
939static struct bio *__bio_map_user_iov(struct request_queue *q,
940                      struct block_device *bdev,
941                      struct sg_iovec *iov, int iov_count,
942                      int write_to_vm, gfp_t gfp_mask)
943{
944    int i, j;
945    int nr_pages = 0;
946    struct page **pages;
947    struct bio *bio;
948    int cur_page = 0;
949    int ret, offset;
950
951    for (i = 0; i < iov_count; i++) {
952        unsigned long uaddr = (unsigned long)iov[i].iov_base;
953        unsigned long len = iov[i].iov_len;
954        unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
955        unsigned long start = uaddr >> PAGE_SHIFT;
956
957        nr_pages += end - start;
958        /*
959         * buffer must be aligned to at least hardsector size for now
960         */
961        if (uaddr & queue_dma_alignment(q))
962            return ERR_PTR(-EINVAL);
963    }
964
965    if (!nr_pages)
966        return ERR_PTR(-EINVAL);
967
968    bio = bio_kmalloc(gfp_mask, nr_pages);
969    if (!bio)
970        return ERR_PTR(-ENOMEM);
971
972    ret = -ENOMEM;
973    pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
974    if (!pages)
975        goto out;
976
977    for (i = 0; i < iov_count; i++) {
978        unsigned long uaddr = (unsigned long)iov[i].iov_base;
979        unsigned long len = iov[i].iov_len;
980        unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
981        unsigned long start = uaddr >> PAGE_SHIFT;
982        const int local_nr_pages = end - start;
983        const int page_limit = cur_page + local_nr_pages;
984        
985        ret = get_user_pages_fast(uaddr, local_nr_pages,
986                write_to_vm, &pages[cur_page]);
987        if (ret < local_nr_pages) {
988            ret = -EFAULT;
989            goto out_unmap;
990        }
991
992        offset = uaddr & ~PAGE_MASK;
993        for (j = cur_page; j < page_limit; j++) {
994            unsigned int bytes = PAGE_SIZE - offset;
995
996            if (len <= 0)
997                break;
998            
999            if (bytes > len)
1000                bytes = len;
1001
1002            /*
1003             * sorry...
1004             */
1005            if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
1006                        bytes)
1007                break;
1008
1009            len -= bytes;
1010            offset = 0;
1011        }
1012
1013        cur_page = j;
1014        /*
1015         * release the pages we didn't map into the bio, if any
1016         */
1017        while (j < page_limit)
1018            page_cache_release(pages[j++]);
1019    }
1020
1021    kfree(pages);
1022
1023    /*
1024     * set data direction, and check if mapped pages need bouncing
1025     */
1026    if (!write_to_vm)
1027        bio->bi_rw |= (1 << BIO_RW);
1028
1029    bio->bi_bdev = bdev;
1030    bio->bi_flags |= (1 << BIO_USER_MAPPED);
1031    return bio;
1032
1033 out_unmap:
1034    for (i = 0; i < nr_pages; i++) {
1035        if(!pages[i])
1036            break;
1037        page_cache_release(pages[i]);
1038    }
1039 out:
1040    kfree(pages);
1041    bio_put(bio);
1042    return ERR_PTR(ret);
1043}
1044
1045/**
1046 * bio_map_user - map user address into bio
1047 * @q: the struct request_queue for the bio
1048 * @bdev: destination block device
1049 * @uaddr: start of user address
1050 * @len: length in bytes
1051 * @write_to_vm: bool indicating writing to pages or not
1052 * @gfp_mask: memory allocation flags
1053 *
1054 * Map the user space address into a bio suitable for io to a block
1055 * device. Returns an error pointer in case of error.
1056 */
1057struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
1058             unsigned long uaddr, unsigned int len, int write_to_vm,
1059             gfp_t gfp_mask)
1060{
1061    struct sg_iovec iov;
1062
1063    iov.iov_base = (void __user *)uaddr;
1064    iov.iov_len = len;
1065
1066    return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
1067}
1068EXPORT_SYMBOL(bio_map_user);
1069
1070/**
1071 * bio_map_user_iov - map user sg_iovec table into bio
1072 * @q: the struct request_queue for the bio
1073 * @bdev: destination block device
1074 * @iov: the iovec.
1075 * @iov_count: number of elements in the iovec
1076 * @write_to_vm: bool indicating writing to pages or not
1077 * @gfp_mask: memory allocation flags
1078 *
1079 * Map the user space address into a bio suitable for io to a block
1080 * device. Returns an error pointer in case of error.
1081 */
1082struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
1083                 struct sg_iovec *iov, int iov_count,
1084                 int write_to_vm, gfp_t gfp_mask)
1085{
1086    struct bio *bio;
1087
1088    bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
1089                 gfp_mask);
1090    if (IS_ERR(bio))
1091        return bio;
1092
1093    /*
1094     * subtle -- if __bio_map_user() ended up bouncing a bio,
1095     * it would normally disappear when its bi_end_io is run.
1096     * however, we need it for the unmap, so grab an extra
1097     * reference to it
1098     */
1099    bio_get(bio);
1100
1101    return bio;
1102}
1103
1104static void __bio_unmap_user(struct bio *bio)
1105{
1106    struct bio_vec *bvec;
1107    int i;
1108
1109    /*
1110     * make sure we dirty pages we wrote to
1111     */
1112    __bio_for_each_segment(bvec, bio, i, 0) {
1113        if (bio_data_dir(bio) == READ)
1114            set_page_dirty_lock(bvec->bv_page);
1115
1116        page_cache_release(bvec->bv_page);
1117    }
1118
1119    bio_put(bio);
1120}
1121
1122/**
1123 * bio_unmap_user - unmap a bio
1124 * @bio: the bio being unmapped
1125 *
1126 * Unmap a bio previously mapped by bio_map_user(). Must be called with
1127 * a process context.
1128 *
1129 * bio_unmap_user() may sleep.
1130 */
1131void bio_unmap_user(struct bio *bio)
1132{
1133    __bio_unmap_user(bio);
1134    bio_put(bio);
1135}
1136EXPORT_SYMBOL(bio_unmap_user);
1137
1138static void bio_map_kern_endio(struct bio *bio, int err)
1139{
1140    bio_put(bio);
1141}
1142
1143static struct bio *__bio_map_kern(struct request_queue *q, void *data,
1144                  unsigned int len, gfp_t gfp_mask)
1145{
1146    unsigned long kaddr = (unsigned long)data;
1147    unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1148    unsigned long start = kaddr >> PAGE_SHIFT;
1149    const int nr_pages = end - start;
1150    int offset, i;
1151    struct bio *bio;
1152
1153    bio = bio_kmalloc(gfp_mask, nr_pages);
1154    if (!bio)
1155        return ERR_PTR(-ENOMEM);
1156
1157    offset = offset_in_page(kaddr);
1158    for (i = 0; i < nr_pages; i++) {
1159        unsigned int bytes = PAGE_SIZE - offset;
1160
1161        if (len <= 0)
1162            break;
1163
1164        if (bytes > len)
1165            bytes = len;
1166
1167        if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1168                    offset) < bytes)
1169            break;
1170
1171        data += bytes;
1172        len -= bytes;
1173        offset = 0;
1174    }
1175
1176    bio->bi_end_io = bio_map_kern_endio;
1177    return bio;
1178}
1179
1180/**
1181 * bio_map_kern - map kernel address into bio
1182 * @q: the struct request_queue for the bio
1183 * @data: pointer to buffer to map
1184 * @len: length in bytes
1185 * @gfp_mask: allocation flags for bio allocation
1186 *
1187 * Map the kernel address into a bio suitable for io to a block
1188 * device. Returns an error pointer in case of error.
1189 */
1190struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1191             gfp_t gfp_mask)
1192{
1193    struct bio *bio;
1194
1195    bio = __bio_map_kern(q, data, len, gfp_mask);
1196    if (IS_ERR(bio))
1197        return bio;
1198
1199    if (bio->bi_size == len)
1200        return bio;
1201
1202    /*
1203     * Don't support partial mappings.
1204     */
1205    bio_put(bio);
1206    return ERR_PTR(-EINVAL);
1207}
1208EXPORT_SYMBOL(bio_map_kern);
1209
1210static void bio_copy_kern_endio(struct bio *bio, int err)
1211{
1212    struct bio_vec *bvec;
1213    const int read = bio_data_dir(bio) == READ;
1214    struct bio_map_data *bmd = bio->bi_private;
1215    int i;
1216    char *p = bmd->sgvecs[0].iov_base;
1217
1218    __bio_for_each_segment(bvec, bio, i, 0) {
1219        char *addr = page_address(bvec->bv_page);
1220        int len = bmd->iovecs[i].bv_len;
1221
1222        if (read)
1223            memcpy(p, addr, len);
1224
1225        __free_page(bvec->bv_page);
1226        p += len;
1227    }
1228
1229    bio_free_map_data(bmd);
1230    bio_put(bio);
1231}
1232
1233/**
1234 * bio_copy_kern - copy kernel address into bio
1235 * @q: the struct request_queue for the bio
1236 * @data: pointer to buffer to copy
1237 * @len: length in bytes
1238 * @gfp_mask: allocation flags for bio and page allocation
1239 * @reading: data direction is READ
1240 *
1241 * copy the kernel address into a bio suitable for io to a block
1242 * device. Returns an error pointer in case of error.
1243 */
1244struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1245              gfp_t gfp_mask, int reading)
1246{
1247    struct bio *bio;
1248    struct bio_vec *bvec;
1249    int i;
1250
1251    bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
1252    if (IS_ERR(bio))
1253        return bio;
1254
1255    if (!reading) {
1256        void *p = data;
1257
1258        bio_for_each_segment(bvec, bio, i) {
1259            char *addr = page_address(bvec->bv_page);
1260
1261            memcpy(addr, p, bvec->bv_len);
1262            p += bvec->bv_len;
1263        }
1264    }
1265
1266    bio->bi_end_io = bio_copy_kern_endio;
1267
1268    return bio;
1269}
1270EXPORT_SYMBOL(bio_copy_kern);
1271
1272/*
1273 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1274 * for performing direct-IO in BIOs.
1275 *
1276 * The problem is that we cannot run set_page_dirty() from interrupt context
1277 * because the required locks are not interrupt-safe. So what we can do is to
1278 * mark the pages dirty _before_ performing IO. And in interrupt context,
1279 * check that the pages are still dirty. If so, fine. If not, redirty them
1280 * in process context.
1281 *
1282 * We special-case compound pages here: normally this means reads into hugetlb
1283 * pages. The logic in here doesn't really work right for compound pages
1284 * because the VM does not uniformly chase down the head page in all cases.
1285 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1286 * handle them at all. So we skip compound pages here at an early stage.
1287 *
1288 * Note that this code is very hard to test under normal circumstances because
1289 * direct-io pins the pages with get_user_pages(). This makes
1290 * is_page_cache_freeable return false, and the VM will not clean the pages.
1291 * But other code (eg, pdflush) could clean the pages if they are mapped
1292 * pagecache.
1293 *
1294 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1295 * deferred bio dirtying paths.
1296 */
1297
1298/*
1299 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1300 */
1301void bio_set_pages_dirty(struct bio *bio)
1302{
1303    struct bio_vec *bvec = bio->bi_io_vec;
1304    int i;
1305
1306    for (i = 0; i < bio->bi_vcnt; i++) {
1307        struct page *page = bvec[i].bv_page;
1308
1309        if (page && !PageCompound(page))
1310            set_page_dirty_lock(page);
1311    }
1312}
1313
1314static void bio_release_pages(struct bio *bio)
1315{
1316    struct bio_vec *bvec = bio->bi_io_vec;
1317    int i;
1318
1319    for (i = 0; i < bio->bi_vcnt; i++) {
1320        struct page *page = bvec[i].bv_page;
1321
1322        if (page)
1323            put_page(page);
1324    }
1325}
1326
1327/*
1328 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1329 * If they are, then fine. If, however, some pages are clean then they must
1330 * have been written out during the direct-IO read. So we take another ref on
1331 * the BIO and the offending pages and re-dirty the pages in process context.
1332 *
1333 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1334 * here on. It will run one page_cache_release() against each page and will
1335 * run one bio_put() against the BIO.
1336 */
1337
1338static void bio_dirty_fn(struct work_struct *work);
1339
1340static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1341static DEFINE_SPINLOCK(bio_dirty_lock);
1342static struct bio *bio_dirty_list;
1343
1344/*
1345 * This runs in process context
1346 */
1347static void bio_dirty_fn(struct work_struct *work)
1348{
1349    unsigned long flags;
1350    struct bio *bio;
1351
1352    spin_lock_irqsave(&bio_dirty_lock, flags);
1353    bio = bio_dirty_list;
1354    bio_dirty_list = NULL;
1355    spin_unlock_irqrestore(&bio_dirty_lock, flags);
1356
1357    while (bio) {
1358        struct bio *next = bio->bi_private;
1359
1360        bio_set_pages_dirty(bio);
1361        bio_release_pages(bio);
1362        bio_put(bio);
1363        bio = next;
1364    }
1365}
1366
1367void bio_check_pages_dirty(struct bio *bio)
1368{
1369    struct bio_vec *bvec = bio->bi_io_vec;
1370    int nr_clean_pages = 0;
1371    int i;
1372
1373    for (i = 0; i < bio->bi_vcnt; i++) {
1374        struct page *page = bvec[i].bv_page;
1375
1376        if (PageDirty(page) || PageCompound(page)) {
1377            page_cache_release(page);
1378            bvec[i].bv_page = NULL;
1379        } else {
1380            nr_clean_pages++;
1381        }
1382    }
1383
1384    if (nr_clean_pages) {
1385        unsigned long flags;
1386
1387        spin_lock_irqsave(&bio_dirty_lock, flags);
1388        bio->bi_private = bio_dirty_list;
1389        bio_dirty_list = bio;
1390        spin_unlock_irqrestore(&bio_dirty_lock, flags);
1391        schedule_work(&bio_dirty_work);
1392    } else {
1393        bio_put(bio);
1394    }
1395}
1396
1397#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1398void bio_flush_dcache_pages(struct bio *bi)
1399{
1400    int i;
1401    struct bio_vec *bvec;
1402
1403    bio_for_each_segment(bvec, bi, i)
1404        flush_dcache_page(bvec->bv_page);
1405}
1406EXPORT_SYMBOL(bio_flush_dcache_pages);
1407#endif
1408
1409/**
1410 * bio_endio - end I/O on a bio
1411 * @bio: bio
1412 * @error: error, if any
1413 *
1414 * Description:
1415 * bio_endio() will end I/O on the whole bio. bio_endio() is the
1416 * preferred way to end I/O on a bio, it takes care of clearing
1417 * BIO_UPTODATE on error. @error is 0 on success, and and one of the
1418 * established -Exxxx (-EIO, for instance) error values in case
1419 * something went wrong. Noone should call bi_end_io() directly on a
1420 * bio unless they own it and thus know that it has an end_io
1421 * function.
1422 **/
1423void bio_endio(struct bio *bio, int error)
1424{
1425    if (error)
1426        clear_bit(BIO_UPTODATE, &bio->bi_flags);
1427    else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1428        error = -EIO;
1429
1430    if (bio->bi_end_io)
1431        bio->bi_end_io(bio, error);
1432}
1433EXPORT_SYMBOL(bio_endio);
1434
1435void bio_pair_release(struct bio_pair *bp)
1436{
1437    if (atomic_dec_and_test(&bp->cnt)) {
1438        struct bio *master = bp->bio1.bi_private;
1439
1440        bio_endio(master, bp->error);
1441        mempool_free(bp, bp->bio2.bi_private);
1442    }
1443}
1444EXPORT_SYMBOL(bio_pair_release);
1445
1446static void bio_pair_end_1(struct bio *bi, int err)
1447{
1448    struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
1449
1450    if (err)
1451        bp->error = err;
1452
1453    bio_pair_release(bp);
1454}
1455
1456static void bio_pair_end_2(struct bio *bi, int err)
1457{
1458    struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
1459
1460    if (err)
1461        bp->error = err;
1462
1463    bio_pair_release(bp);
1464}
1465
1466/*
1467 * split a bio - only worry about a bio with a single page in its iovec
1468 */
1469struct bio_pair *bio_split(struct bio *bi, int first_sectors)
1470{
1471    struct bio_pair *bp = mempool_alloc(bio_split_pool, GFP_NOIO);
1472
1473    if (!bp)
1474        return bp;
1475
1476    trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
1477                bi->bi_sector + first_sectors);
1478
1479    BUG_ON(bi->bi_vcnt != 1);
1480    BUG_ON(bi->bi_idx != 0);
1481    atomic_set(&bp->cnt, 3);
1482    bp->error = 0;
1483    bp->bio1 = *bi;
1484    bp->bio2 = *bi;
1485    bp->bio2.bi_sector += first_sectors;
1486    bp->bio2.bi_size -= first_sectors << 9;
1487    bp->bio1.bi_size = first_sectors << 9;
1488
1489    bp->bv1 = bi->bi_io_vec[0];
1490    bp->bv2 = bi->bi_io_vec[0];
1491    bp->bv2.bv_offset += first_sectors << 9;
1492    bp->bv2.bv_len -= first_sectors << 9;
1493    bp->bv1.bv_len = first_sectors << 9;
1494
1495    bp->bio1.bi_io_vec = &bp->bv1;
1496    bp->bio2.bi_io_vec = &bp->bv2;
1497
1498    bp->bio1.bi_max_vecs = 1;
1499    bp->bio2.bi_max_vecs = 1;
1500
1501    bp->bio1.bi_end_io = bio_pair_end_1;
1502    bp->bio2.bi_end_io = bio_pair_end_2;
1503
1504    bp->bio1.bi_private = bi;
1505    bp->bio2.bi_private = bio_split_pool;
1506
1507    if (bio_integrity(bi))
1508        bio_integrity_split(bi, bp, first_sectors);
1509
1510    return bp;
1511}
1512EXPORT_SYMBOL(bio_split);
1513
1514/**
1515 * bio_sector_offset - Find hardware sector offset in bio
1516 * @bio: bio to inspect
1517 * @index: bio_vec index
1518 * @offset: offset in bv_page
1519 *
1520 * Return the number of hardware sectors between beginning of bio
1521 * and an end point indicated by a bio_vec index and an offset
1522 * within that vector's page.
1523 */
1524sector_t bio_sector_offset(struct bio *bio, unsigned short index,
1525               unsigned int offset)
1526{
1527    unsigned int sector_sz;
1528    struct bio_vec *bv;
1529    sector_t sectors;
1530    int i;
1531
1532    sector_sz = queue_logical_block_size(bio->bi_bdev->bd_disk->queue);
1533    sectors = 0;
1534
1535    if (index >= bio->bi_idx)
1536        index = bio->bi_vcnt - 1;
1537
1538    __bio_for_each_segment(bv, bio, i, 0) {
1539        if (i == index) {
1540            if (offset > bv->bv_offset)
1541                sectors += (offset - bv->bv_offset) / sector_sz;
1542            break;
1543        }
1544
1545        sectors += bv->bv_len / sector_sz;
1546    }
1547
1548    return sectors;
1549}
1550EXPORT_SYMBOL(bio_sector_offset);
1551
1552/*
1553 * create memory pools for biovec's in a bio_set.
1554 * use the global biovec slabs created for general use.
1555 */
1556static int biovec_create_pools(struct bio_set *bs, int pool_entries)
1557{
1558    struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
1559
1560    bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
1561    if (!bs->bvec_pool)
1562        return -ENOMEM;
1563
1564    return 0;
1565}
1566
1567static void biovec_free_pools(struct bio_set *bs)
1568{
1569    mempool_destroy(bs->bvec_pool);
1570}
1571
1572void bioset_free(struct bio_set *bs)
1573{
1574    if (bs->bio_pool)
1575        mempool_destroy(bs->bio_pool);
1576
1577    bioset_integrity_free(bs);
1578    biovec_free_pools(bs);
1579    bio_put_slab(bs);
1580
1581    kfree(bs);
1582}
1583EXPORT_SYMBOL(bioset_free);
1584
1585/**
1586 * bioset_create - Create a bio_set
1587 * @pool_size: Number of bio and bio_vecs to cache in the mempool
1588 * @front_pad: Number of bytes to allocate in front of the returned bio
1589 *
1590 * Description:
1591 * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1592 * to ask for a number of bytes to be allocated in front of the bio.
1593 * Front pad allocation is useful for embedding the bio inside
1594 * another structure, to avoid allocating extra data to go with the bio.
1595 * Note that the bio must be embedded at the END of that structure always,
1596 * or things will break badly.
1597 */
1598struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
1599{
1600    unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1601    struct bio_set *bs;
1602
1603    bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1604    if (!bs)
1605        return NULL;
1606
1607    bs->front_pad = front_pad;
1608
1609    bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1610    if (!bs->bio_slab) {
1611        kfree(bs);
1612        return NULL;
1613    }
1614
1615    bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
1616    if (!bs->bio_pool)
1617        goto bad;
1618
1619    if (bioset_integrity_create(bs, pool_size))
1620        goto bad;
1621
1622    if (!biovec_create_pools(bs, pool_size))
1623        return bs;
1624
1625bad:
1626    bioset_free(bs);
1627    return NULL;
1628}
1629EXPORT_SYMBOL(bioset_create);
1630
1631static void __init biovec_init_slabs(void)
1632{
1633    int i;
1634
1635    for (i = 0; i < BIOVEC_NR_POOLS; i++) {
1636        int size;
1637        struct biovec_slab *bvs = bvec_slabs + i;
1638
1639#ifndef CONFIG_BLK_DEV_INTEGRITY
1640        if (bvs->nr_vecs <= BIO_INLINE_VECS) {
1641            bvs->slab = NULL;
1642            continue;
1643        }
1644#endif
1645
1646        size = bvs->nr_vecs * sizeof(struct bio_vec);
1647        bvs->slab = kmem_cache_create(bvs->name, size, 0,
1648                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1649    }
1650}
1651
1652static int __init init_bio(void)
1653{
1654    bio_slab_max = 2;
1655    bio_slab_nr = 0;
1656    bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
1657    if (!bio_slabs)
1658        panic("bio: can't allocate bios\n");
1659
1660    bio_integrity_init();
1661    biovec_init_slabs();
1662
1663    fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
1664    if (!fs_bio_set)
1665        panic("bio: can't allocate bios\n");
1666
1667    bio_split_pool = mempool_create_kmalloc_pool(BIO_SPLIT_ENTRIES,
1668                             sizeof(struct bio_pair));
1669    if (!bio_split_pool)
1670        panic("bio: can't create split pool\n");
1671
1672    return 0;
1673}
1674subsys_initcall(init_bio);
1675

Archive Download this file



interactive