2 * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
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.
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.
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-
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 <linux/blktrace_api.h>
29 #include <trace/block.h>
30 #include <scsi/sg.h> /* for struct sg_iovec */
32 DEFINE_TRACE(block_split);
35 * Test patch to inline a certain number of bi_io_vec's inside the bio
36 * itself, to shrink a bio data allocation from two mempool calls to one
38 #define BIO_INLINE_VECS 4
40 static mempool_t *bio_split_pool __read_mostly;
43 * if you change this list, also change bvec_alloc or things will
44 * break badly! cannot be bigger than what you can fit into an
47 #define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
48 struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
49 BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
54 * fs_bio_set is the bio_set containing bio and iovec memory pools used by
55 * IO code that does not need private memory pools.
57 struct bio_set *fs_bio_set;
60 * Our slab pool management
63 struct kmem_cache *slab;
64 unsigned int slab_ref;
65 unsigned int slab_size;
68 static DEFINE_MUTEX(bio_slab_lock);
69 static struct bio_slab *bio_slabs;
70 static unsigned int bio_slab_nr, bio_slab_max;
72 static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
74 unsigned int sz = sizeof(struct bio) + extra_size;
75 struct kmem_cache *slab = NULL;
76 struct bio_slab *bslab;
77 unsigned int i, entry = -1;
79 mutex_lock(&bio_slab_lock);
82 while (i < bio_slab_nr) {
83 struct bio_slab *bslab = &bio_slabs[i];
85 if (!bslab->slab && entry == -1)
87 else if (bslab->slab_size == sz) {
98 if (bio_slab_nr == bio_slab_max && entry == -1) {
100 bio_slabs = krealloc(bio_slabs,
101 bio_slab_max * sizeof(struct bio_slab),
107 entry = bio_slab_nr++;
109 bslab = &bio_slabs[entry];
111 snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
112 slab = kmem_cache_create(bslab->name, sz, 0, SLAB_HWCACHE_ALIGN, NULL);
116 printk("bio: create slab <%s> at %d\n", bslab->name, entry);
119 bslab->slab_size = sz;
121 mutex_unlock(&bio_slab_lock);
125 static void bio_put_slab(struct bio_set *bs)
127 struct bio_slab *bslab = NULL;
130 mutex_lock(&bio_slab_lock);
132 for (i = 0; i < bio_slab_nr; i++) {
133 if (bs->bio_slab == bio_slabs[i].slab) {
134 bslab = &bio_slabs[i];
139 if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
142 WARN_ON(!bslab->slab_ref);
144 if (--bslab->slab_ref)
147 kmem_cache_destroy(bslab->slab);
151 mutex_unlock(&bio_slab_lock);
154 unsigned int bvec_nr_vecs(unsigned short idx)
156 return bvec_slabs[idx].nr_vecs;
159 void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
161 BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
163 if (idx == BIOVEC_MAX_IDX)
164 mempool_free(bv, bs->bvec_pool);
166 struct biovec_slab *bvs = bvec_slabs + idx;
168 kmem_cache_free(bvs->slab, bv);
172 struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
178 * If 'bs' is given, lookup the pool and do the mempool alloc.
179 * If not, this is a bio_kmalloc() allocation and just do a
180 * kzalloc() for the exact number of vecs right away.
183 bvl = kmalloc(nr * sizeof(struct bio_vec), gfp_mask);
186 * see comment near bvec_array define!
204 case 129 ... BIO_MAX_PAGES:
212 * idx now points to the pool we want to allocate from. only the
213 * 1-vec entry pool is mempool backed.
215 if (*idx == BIOVEC_MAX_IDX) {
217 bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
219 struct biovec_slab *bvs = bvec_slabs + *idx;
220 gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
223 * Make this allocation restricted and don't dump info on
224 * allocation failures, since we'll fallback to the mempool
225 * in case of failure.
227 __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
230 * Try a slab allocation. If this fails and __GFP_WAIT
231 * is set, retry with the 1-entry mempool
233 bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
234 if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
235 *idx = BIOVEC_MAX_IDX;
243 void bio_free(struct bio *bio, struct bio_set *bs)
247 if (bio_has_allocated_vec(bio))
248 bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
250 if (bio_integrity(bio))
251 bio_integrity_free(bio, bs);
254 * If we have front padding, adjust the bio pointer before freeing
260 mempool_free(p, bs->bio_pool);
264 * default destructor for a bio allocated with bio_alloc_bioset()
266 static void bio_fs_destructor(struct bio *bio)
268 bio_free(bio, fs_bio_set);
271 static void bio_kmalloc_destructor(struct bio *bio)
273 if (bio_has_allocated_vec(bio))
274 kfree(bio->bi_io_vec);
278 void bio_init(struct bio *bio)
280 memset(bio, 0, sizeof(*bio));
281 bio->bi_flags = 1 << BIO_UPTODATE;
282 bio->bi_comp_cpu = -1;
283 atomic_set(&bio->bi_cnt, 1);
287 * bio_alloc_bioset - allocate a bio for I/O
288 * @gfp_mask: the GFP_ mask given to the slab allocator
289 * @nr_iovecs: number of iovecs to pre-allocate
290 * @bs: the bio_set to allocate from. If %NULL, just use kmalloc
293 * bio_alloc_bioset will first try its own mempool to satisfy the allocation.
294 * If %__GFP_WAIT is set then we will block on the internal pool waiting
295 * for a &struct bio to become free. If a %NULL @bs is passed in, we will
296 * fall back to just using @kmalloc to allocate the required memory.
298 * Note that the caller must set ->bi_destructor on succesful return
299 * of a bio, to do the appropriate freeing of the bio once the reference
300 * count drops to zero.
302 struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
304 struct bio *bio = NULL;
307 void *p = mempool_alloc(bs->bio_pool, gfp_mask);
310 bio = p + bs->front_pad;
312 bio = kmalloc(sizeof(*bio), gfp_mask);
315 struct bio_vec *bvl = NULL;
318 if (likely(nr_iovecs)) {
319 unsigned long uninitialized_var(idx);
321 if (nr_iovecs <= BIO_INLINE_VECS) {
323 bvl = bio->bi_inline_vecs;
324 nr_iovecs = BIO_INLINE_VECS;
326 bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx,
328 nr_iovecs = bvec_nr_vecs(idx);
330 if (unlikely(!bvl)) {
332 mempool_free(bio, bs->bio_pool);
338 bio->bi_flags |= idx << BIO_POOL_OFFSET;
339 bio->bi_max_vecs = nr_iovecs;
341 bio->bi_io_vec = bvl;
347 struct bio *bio_alloc(gfp_t gfp_mask, int nr_iovecs)
349 struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
352 bio->bi_destructor = bio_fs_destructor;
358 * Like bio_alloc(), but doesn't use a mempool backing. This means that
359 * it CAN fail, but while bio_alloc() can only be used for allocations
360 * that have a short (finite) life span, bio_kmalloc() should be used
361 * for more permanent bio allocations (like allocating some bio's for
362 * initalization or setup purposes).
364 struct bio *bio_kmalloc(gfp_t gfp_mask, int nr_iovecs)
366 struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
369 bio->bi_destructor = bio_kmalloc_destructor;
374 void zero_fill_bio(struct bio *bio)
380 bio_for_each_segment(bv, bio, i) {
381 char *data = bvec_kmap_irq(bv, &flags);
382 memset(data, 0, bv->bv_len);
383 flush_dcache_page(bv->bv_page);
384 bvec_kunmap_irq(data, &flags);
387 EXPORT_SYMBOL(zero_fill_bio);
390 * bio_put - release a reference to a bio
391 * @bio: bio to release reference to
394 * Put a reference to a &struct bio, either one you have gotten with
395 * bio_alloc or bio_get. The last put of a bio will free it.
397 void bio_put(struct bio *bio)
399 BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
404 if (atomic_dec_and_test(&bio->bi_cnt)) {
406 bio->bi_destructor(bio);
410 inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
412 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
413 blk_recount_segments(q, bio);
415 return bio->bi_phys_segments;
419 * __bio_clone - clone a bio
420 * @bio: destination bio
421 * @bio_src: bio to clone
423 * Clone a &bio. Caller will own the returned bio, but not
424 * the actual data it points to. Reference count of returned
427 void __bio_clone(struct bio *bio, struct bio *bio_src)
429 memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
430 bio_src->bi_max_vecs * sizeof(struct bio_vec));
433 * most users will be overriding ->bi_bdev with a new target,
434 * so we don't set nor calculate new physical/hw segment counts here
436 bio->bi_sector = bio_src->bi_sector;
437 bio->bi_bdev = bio_src->bi_bdev;
438 bio->bi_flags |= 1 << BIO_CLONED;
439 bio->bi_rw = bio_src->bi_rw;
440 bio->bi_vcnt = bio_src->bi_vcnt;
441 bio->bi_size = bio_src->bi_size;
442 bio->bi_idx = bio_src->bi_idx;
446 * bio_clone - clone a bio
448 * @gfp_mask: allocation priority
450 * Like __bio_clone, only also allocates the returned bio
452 struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
454 struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set);
459 b->bi_destructor = bio_fs_destructor;
462 if (bio_integrity(bio)) {
465 ret = bio_integrity_clone(b, bio, fs_bio_set);
475 * bio_get_nr_vecs - return approx number of vecs
478 * Return the approximate number of pages we can send to this target.
479 * There's no guarantee that you will be able to fit this number of pages
480 * into a bio, it does not account for dynamic restrictions that vary
483 int bio_get_nr_vecs(struct block_device *bdev)
485 struct request_queue *q = bdev_get_queue(bdev);
488 nr_pages = ((q->max_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
489 if (nr_pages > q->max_phys_segments)
490 nr_pages = q->max_phys_segments;
491 if (nr_pages > q->max_hw_segments)
492 nr_pages = q->max_hw_segments;
497 static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
498 *page, unsigned int len, unsigned int offset,
499 unsigned short max_sectors)
501 int retried_segments = 0;
502 struct bio_vec *bvec;
505 * cloned bio must not modify vec list
507 if (unlikely(bio_flagged(bio, BIO_CLONED)))
510 if (((bio->bi_size + len) >> 9) > max_sectors)
514 * For filesystems with a blocksize smaller than the pagesize
515 * we will often be called with the same page as last time and
516 * a consecutive offset. Optimize this special case.
518 if (bio->bi_vcnt > 0) {
519 struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
521 if (page == prev->bv_page &&
522 offset == prev->bv_offset + prev->bv_len) {
525 if (q->merge_bvec_fn) {
526 struct bvec_merge_data bvm = {
527 .bi_bdev = bio->bi_bdev,
528 .bi_sector = bio->bi_sector,
529 .bi_size = bio->bi_size,
533 if (q->merge_bvec_fn(q, &bvm, prev) < len) {
543 if (bio->bi_vcnt >= bio->bi_max_vecs)
547 * we might lose a segment or two here, but rather that than
548 * make this too complex.
551 while (bio->bi_phys_segments >= q->max_phys_segments
552 || bio->bi_phys_segments >= q->max_hw_segments) {
554 if (retried_segments)
557 retried_segments = 1;
558 blk_recount_segments(q, bio);
562 * setup the new entry, we might clear it again later if we
563 * cannot add the page
565 bvec = &bio->bi_io_vec[bio->bi_vcnt];
566 bvec->bv_page = page;
568 bvec->bv_offset = offset;
571 * if queue has other restrictions (eg varying max sector size
572 * depending on offset), it can specify a merge_bvec_fn in the
573 * queue to get further control
575 if (q->merge_bvec_fn) {
576 struct bvec_merge_data bvm = {
577 .bi_bdev = bio->bi_bdev,
578 .bi_sector = bio->bi_sector,
579 .bi_size = bio->bi_size,
584 * merge_bvec_fn() returns number of bytes it can accept
587 if (q->merge_bvec_fn(q, &bvm, bvec) < len) {
588 bvec->bv_page = NULL;
595 /* If we may be able to merge these biovecs, force a recount */
596 if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
597 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
600 bio->bi_phys_segments++;
607 * bio_add_pc_page - attempt to add page to bio
608 * @q: the target queue
609 * @bio: destination bio
611 * @len: vec entry length
612 * @offset: vec entry offset
614 * Attempt to add a page to the bio_vec maplist. This can fail for a
615 * number of reasons, such as the bio being full or target block
616 * device limitations. The target block device must allow bio's
617 * smaller than PAGE_SIZE, so it is always possible to add a single
618 * page to an empty bio. This should only be used by REQ_PC bios.
620 int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
621 unsigned int len, unsigned int offset)
623 return __bio_add_page(q, bio, page, len, offset, q->max_hw_sectors);
627 * bio_add_page - attempt to add page to bio
628 * @bio: destination bio
630 * @len: vec entry length
631 * @offset: vec entry offset
633 * Attempt to add a page to the bio_vec maplist. This can fail for a
634 * number of reasons, such as the bio being full or target block
635 * device limitations. The target block device must allow bio's
636 * smaller than PAGE_SIZE, so it is always possible to add a single
637 * page to an empty bio.
639 int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
642 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
643 return __bio_add_page(q, bio, page, len, offset, q->max_sectors);
646 struct bio_map_data {
647 struct bio_vec *iovecs;
648 struct sg_iovec *sgvecs;
653 static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
654 struct sg_iovec *iov, int iov_count,
657 memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
658 memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
659 bmd->nr_sgvecs = iov_count;
660 bmd->is_our_pages = is_our_pages;
661 bio->bi_private = bmd;
664 static void bio_free_map_data(struct bio_map_data *bmd)
671 static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
674 struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);
679 bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
685 bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
694 static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
695 struct sg_iovec *iov, int iov_count, int uncopy,
699 struct bio_vec *bvec;
701 unsigned int iov_off = 0;
702 int read = bio_data_dir(bio) == READ;
704 __bio_for_each_segment(bvec, bio, i, 0) {
705 char *bv_addr = page_address(bvec->bv_page);
706 unsigned int bv_len = iovecs[i].bv_len;
708 while (bv_len && iov_idx < iov_count) {
712 bytes = min_t(unsigned int,
713 iov[iov_idx].iov_len - iov_off, bv_len);
714 iov_addr = iov[iov_idx].iov_base + iov_off;
717 if (!read && !uncopy)
718 ret = copy_from_user(bv_addr, iov_addr,
721 ret = copy_to_user(iov_addr, bv_addr,
733 if (iov[iov_idx].iov_len == iov_off) {
740 __free_page(bvec->bv_page);
747 * bio_uncopy_user - finish previously mapped bio
748 * @bio: bio being terminated
750 * Free pages allocated from bio_copy_user() and write back data
751 * to user space in case of a read.
753 int bio_uncopy_user(struct bio *bio)
755 struct bio_map_data *bmd = bio->bi_private;
758 if (!bio_flagged(bio, BIO_NULL_MAPPED))
759 ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
760 bmd->nr_sgvecs, 1, bmd->is_our_pages);
761 bio_free_map_data(bmd);
767 * bio_copy_user_iov - copy user data to bio
768 * @q: destination block queue
769 * @map_data: pointer to the rq_map_data holding pages (if necessary)
771 * @iov_count: number of elements in the iovec
772 * @write_to_vm: bool indicating writing to pages or not
773 * @gfp_mask: memory allocation flags
775 * Prepares and returns a bio for indirect user io, bouncing data
776 * to/from kernel pages as necessary. Must be paired with
777 * call bio_uncopy_user() on io completion.
779 struct bio *bio_copy_user_iov(struct request_queue *q,
780 struct rq_map_data *map_data,
781 struct sg_iovec *iov, int iov_count,
782 int write_to_vm, gfp_t gfp_mask)
784 struct bio_map_data *bmd;
785 struct bio_vec *bvec;
790 unsigned int len = 0;
791 unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
793 for (i = 0; i < iov_count; i++) {
798 uaddr = (unsigned long)iov[i].iov_base;
799 end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
800 start = uaddr >> PAGE_SHIFT;
802 nr_pages += end - start;
803 len += iov[i].iov_len;
806 bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
808 return ERR_PTR(-ENOMEM);
811 bio = bio_alloc(gfp_mask, nr_pages);
815 bio->bi_rw |= (!write_to_vm << BIO_RW);
820 nr_pages = 1 << map_data->page_order;
821 i = map_data->offset / PAGE_SIZE;
824 unsigned int bytes = PAGE_SIZE;
832 if (i == map_data->nr_entries * nr_pages) {
837 page = map_data->pages[i / nr_pages];
838 page += (i % nr_pages);
842 page = alloc_page(q->bounce_gfp | gfp_mask);
849 if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
862 if (!write_to_vm && (!map_data || !map_data->null_mapped)) {
863 ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
868 bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
872 bio_for_each_segment(bvec, bio, i)
873 __free_page(bvec->bv_page);
877 bio_free_map_data(bmd);
882 * bio_copy_user - copy user data to bio
883 * @q: destination block queue
884 * @map_data: pointer to the rq_map_data holding pages (if necessary)
885 * @uaddr: start of user address
886 * @len: length in bytes
887 * @write_to_vm: bool indicating writing to pages or not
888 * @gfp_mask: memory allocation flags
890 * Prepares and returns a bio for indirect user io, bouncing data
891 * to/from kernel pages as necessary. Must be paired with
892 * call bio_uncopy_user() on io completion.
894 struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
895 unsigned long uaddr, unsigned int len,
896 int write_to_vm, gfp_t gfp_mask)
900 iov.iov_base = (void __user *)uaddr;
903 return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
906 static struct bio *__bio_map_user_iov(struct request_queue *q,
907 struct block_device *bdev,
908 struct sg_iovec *iov, int iov_count,
909 int write_to_vm, gfp_t gfp_mask)
918 for (i = 0; i < iov_count; i++) {
919 unsigned long uaddr = (unsigned long)iov[i].iov_base;
920 unsigned long len = iov[i].iov_len;
921 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
922 unsigned long start = uaddr >> PAGE_SHIFT;
924 nr_pages += end - start;
926 * buffer must be aligned to at least hardsector size for now
928 if (uaddr & queue_dma_alignment(q))
929 return ERR_PTR(-EINVAL);
933 return ERR_PTR(-EINVAL);
935 bio = bio_alloc(gfp_mask, nr_pages);
937 return ERR_PTR(-ENOMEM);
940 pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
944 for (i = 0; i < iov_count; i++) {
945 unsigned long uaddr = (unsigned long)iov[i].iov_base;
946 unsigned long len = iov[i].iov_len;
947 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
948 unsigned long start = uaddr >> PAGE_SHIFT;
949 const int local_nr_pages = end - start;
950 const int page_limit = cur_page + local_nr_pages;
952 ret = get_user_pages_fast(uaddr, local_nr_pages,
953 write_to_vm, &pages[cur_page]);
954 if (ret < local_nr_pages) {
959 offset = uaddr & ~PAGE_MASK;
960 for (j = cur_page; j < page_limit; j++) {
961 unsigned int bytes = PAGE_SIZE - offset;
972 if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
982 * release the pages we didn't map into the bio, if any
984 while (j < page_limit)
985 page_cache_release(pages[j++]);
991 * set data direction, and check if mapped pages need bouncing
994 bio->bi_rw |= (1 << BIO_RW);
997 bio->bi_flags |= (1 << BIO_USER_MAPPED);
1001 for (i = 0; i < nr_pages; i++) {
1004 page_cache_release(pages[i]);
1009 return ERR_PTR(ret);
1013 * bio_map_user - map user address into bio
1014 * @q: the struct request_queue for the bio
1015 * @bdev: destination block device
1016 * @uaddr: start of user address
1017 * @len: length in bytes
1018 * @write_to_vm: bool indicating writing to pages or not
1019 * @gfp_mask: memory allocation flags
1021 * Map the user space address into a bio suitable for io to a block
1022 * device. Returns an error pointer in case of error.
1024 struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
1025 unsigned long uaddr, unsigned int len, int write_to_vm,
1028 struct sg_iovec iov;
1030 iov.iov_base = (void __user *)uaddr;
1033 return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
1037 * bio_map_user_iov - map user sg_iovec table into bio
1038 * @q: the struct request_queue for the bio
1039 * @bdev: destination block device
1041 * @iov_count: number of elements in the iovec
1042 * @write_to_vm: bool indicating writing to pages or not
1043 * @gfp_mask: memory allocation flags
1045 * Map the user space address into a bio suitable for io to a block
1046 * device. Returns an error pointer in case of error.
1048 struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
1049 struct sg_iovec *iov, int iov_count,
1050 int write_to_vm, gfp_t gfp_mask)
1054 bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
1060 * subtle -- if __bio_map_user() ended up bouncing a bio,
1061 * it would normally disappear when its bi_end_io is run.
1062 * however, we need it for the unmap, so grab an extra
1070 static void __bio_unmap_user(struct bio *bio)
1072 struct bio_vec *bvec;
1076 * make sure we dirty pages we wrote to
1078 __bio_for_each_segment(bvec, bio, i, 0) {
1079 if (bio_data_dir(bio) == READ)
1080 set_page_dirty_lock(bvec->bv_page);
1082 page_cache_release(bvec->bv_page);
1089 * bio_unmap_user - unmap a bio
1090 * @bio: the bio being unmapped
1092 * Unmap a bio previously mapped by bio_map_user(). Must be called with
1093 * a process context.
1095 * bio_unmap_user() may sleep.
1097 void bio_unmap_user(struct bio *bio)
1099 __bio_unmap_user(bio);
1103 static void bio_map_kern_endio(struct bio *bio, int err)
1109 static struct bio *__bio_map_kern(struct request_queue *q, void *data,
1110 unsigned int len, gfp_t gfp_mask)
1112 unsigned long kaddr = (unsigned long)data;
1113 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1114 unsigned long start = kaddr >> PAGE_SHIFT;
1115 const int nr_pages = end - start;
1119 bio = bio_alloc(gfp_mask, nr_pages);
1121 return ERR_PTR(-ENOMEM);
1123 offset = offset_in_page(kaddr);
1124 for (i = 0; i < nr_pages; i++) {
1125 unsigned int bytes = PAGE_SIZE - offset;
1133 if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1142 bio->bi_end_io = bio_map_kern_endio;
1147 * bio_map_kern - map kernel address into bio
1148 * @q: the struct request_queue for the bio
1149 * @data: pointer to buffer to map
1150 * @len: length in bytes
1151 * @gfp_mask: allocation flags for bio allocation
1153 * Map the kernel address into a bio suitable for io to a block
1154 * device. Returns an error pointer in case of error.
1156 struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1161 bio = __bio_map_kern(q, data, len, gfp_mask);
1165 if (bio->bi_size == len)
1169 * Don't support partial mappings.
1172 return ERR_PTR(-EINVAL);
1175 static void bio_copy_kern_endio(struct bio *bio, int err)
1177 struct bio_vec *bvec;
1178 const int read = bio_data_dir(bio) == READ;
1179 struct bio_map_data *bmd = bio->bi_private;
1181 char *p = bmd->sgvecs[0].iov_base;
1183 __bio_for_each_segment(bvec, bio, i, 0) {
1184 char *addr = page_address(bvec->bv_page);
1185 int len = bmd->iovecs[i].bv_len;
1188 memcpy(p, addr, len);
1190 __free_page(bvec->bv_page);
1194 bio_free_map_data(bmd);
1199 * bio_copy_kern - copy kernel address into bio
1200 * @q: the struct request_queue for the bio
1201 * @data: pointer to buffer to copy
1202 * @len: length in bytes
1203 * @gfp_mask: allocation flags for bio and page allocation
1204 * @reading: data direction is READ
1206 * copy the kernel address into a bio suitable for io to a block
1207 * device. Returns an error pointer in case of error.
1209 struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1210 gfp_t gfp_mask, int reading)
1213 struct bio_vec *bvec;
1216 bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
1223 bio_for_each_segment(bvec, bio, i) {
1224 char *addr = page_address(bvec->bv_page);
1226 memcpy(addr, p, bvec->bv_len);
1231 bio->bi_end_io = bio_copy_kern_endio;
1237 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1238 * for performing direct-IO in BIOs.
1240 * The problem is that we cannot run set_page_dirty() from interrupt context
1241 * because the required locks are not interrupt-safe. So what we can do is to
1242 * mark the pages dirty _before_ performing IO. And in interrupt context,
1243 * check that the pages are still dirty. If so, fine. If not, redirty them
1244 * in process context.
1246 * We special-case compound pages here: normally this means reads into hugetlb
1247 * pages. The logic in here doesn't really work right for compound pages
1248 * because the VM does not uniformly chase down the head page in all cases.
1249 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1250 * handle them at all. So we skip compound pages here at an early stage.
1252 * Note that this code is very hard to test under normal circumstances because
1253 * direct-io pins the pages with get_user_pages(). This makes
1254 * is_page_cache_freeable return false, and the VM will not clean the pages.
1255 * But other code (eg, pdflush) could clean the pages if they are mapped
1258 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1259 * deferred bio dirtying paths.
1263 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1265 void bio_set_pages_dirty(struct bio *bio)
1267 struct bio_vec *bvec = bio->bi_io_vec;
1270 for (i = 0; i < bio->bi_vcnt; i++) {
1271 struct page *page = bvec[i].bv_page;
1273 if (page && !PageCompound(page))
1274 set_page_dirty_lock(page);
1278 static void bio_release_pages(struct bio *bio)
1280 struct bio_vec *bvec = bio->bi_io_vec;
1283 for (i = 0; i < bio->bi_vcnt; i++) {
1284 struct page *page = bvec[i].bv_page;
1292 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1293 * If they are, then fine. If, however, some pages are clean then they must
1294 * have been written out during the direct-IO read. So we take another ref on
1295 * the BIO and the offending pages and re-dirty the pages in process context.
1297 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1298 * here on. It will run one page_cache_release() against each page and will
1299 * run one bio_put() against the BIO.
1302 static void bio_dirty_fn(struct work_struct *work);
1304 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1305 static DEFINE_SPINLOCK(bio_dirty_lock);
1306 static struct bio *bio_dirty_list;
1309 * This runs in process context
1311 static void bio_dirty_fn(struct work_struct *work)
1313 unsigned long flags;
1316 spin_lock_irqsave(&bio_dirty_lock, flags);
1317 bio = bio_dirty_list;
1318 bio_dirty_list = NULL;
1319 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1322 struct bio *next = bio->bi_private;
1324 bio_set_pages_dirty(bio);
1325 bio_release_pages(bio);
1331 void bio_check_pages_dirty(struct bio *bio)
1333 struct bio_vec *bvec = bio->bi_io_vec;
1334 int nr_clean_pages = 0;
1337 for (i = 0; i < bio->bi_vcnt; i++) {
1338 struct page *page = bvec[i].bv_page;
1340 if (PageDirty(page) || PageCompound(page)) {
1341 page_cache_release(page);
1342 bvec[i].bv_page = NULL;
1348 if (nr_clean_pages) {
1349 unsigned long flags;
1351 spin_lock_irqsave(&bio_dirty_lock, flags);
1352 bio->bi_private = bio_dirty_list;
1353 bio_dirty_list = bio;
1354 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1355 schedule_work(&bio_dirty_work);
1362 * bio_endio - end I/O on a bio
1364 * @error: error, if any
1367 * bio_endio() will end I/O on the whole bio. bio_endio() is the
1368 * preferred way to end I/O on a bio, it takes care of clearing
1369 * BIO_UPTODATE on error. @error is 0 on success, and and one of the
1370 * established -Exxxx (-EIO, for instance) error values in case
1371 * something went wrong. Noone should call bi_end_io() directly on a
1372 * bio unless they own it and thus know that it has an end_io
1375 void bio_endio(struct bio *bio, int error)
1378 clear_bit(BIO_UPTODATE, &bio->bi_flags);
1379 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1383 bio->bi_end_io(bio, error);
1386 void bio_pair_release(struct bio_pair *bp)
1388 if (atomic_dec_and_test(&bp->cnt)) {
1389 struct bio *master = bp->bio1.bi_private;
1391 bio_endio(master, bp->error);
1392 mempool_free(bp, bp->bio2.bi_private);
1396 static void bio_pair_end_1(struct bio *bi, int err)
1398 struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
1403 bio_pair_release(bp);
1406 static void bio_pair_end_2(struct bio *bi, int err)
1408 struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
1413 bio_pair_release(bp);
1417 * split a bio - only worry about a bio with a single page
1420 struct bio_pair *bio_split(struct bio *bi, int first_sectors)
1422 struct bio_pair *bp = mempool_alloc(bio_split_pool, GFP_NOIO);
1427 trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
1428 bi->bi_sector + first_sectors);
1430 BUG_ON(bi->bi_vcnt != 1);
1431 BUG_ON(bi->bi_idx != 0);
1432 atomic_set(&bp->cnt, 3);
1436 bp->bio2.bi_sector += first_sectors;
1437 bp->bio2.bi_size -= first_sectors << 9;
1438 bp->bio1.bi_size = first_sectors << 9;
1440 bp->bv1 = bi->bi_io_vec[0];
1441 bp->bv2 = bi->bi_io_vec[0];
1442 bp->bv2.bv_offset += first_sectors << 9;
1443 bp->bv2.bv_len -= first_sectors << 9;
1444 bp->bv1.bv_len = first_sectors << 9;
1446 bp->bio1.bi_io_vec = &bp->bv1;
1447 bp->bio2.bi_io_vec = &bp->bv2;
1449 bp->bio1.bi_max_vecs = 1;
1450 bp->bio2.bi_max_vecs = 1;
1452 bp->bio1.bi_end_io = bio_pair_end_1;
1453 bp->bio2.bi_end_io = bio_pair_end_2;
1455 bp->bio1.bi_private = bi;
1456 bp->bio2.bi_private = bio_split_pool;
1458 if (bio_integrity(bi))
1459 bio_integrity_split(bi, bp, first_sectors);
1465 * bio_sector_offset - Find hardware sector offset in bio
1466 * @bio: bio to inspect
1467 * @index: bio_vec index
1468 * @offset: offset in bv_page
1470 * Return the number of hardware sectors between beginning of bio
1471 * and an end point indicated by a bio_vec index and an offset
1472 * within that vector's page.
1474 sector_t bio_sector_offset(struct bio *bio, unsigned short index,
1475 unsigned int offset)
1477 unsigned int sector_sz = queue_hardsect_size(bio->bi_bdev->bd_disk->queue);
1484 if (index >= bio->bi_idx)
1485 index = bio->bi_vcnt - 1;
1487 __bio_for_each_segment(bv, bio, i, 0) {
1489 if (offset > bv->bv_offset)
1490 sectors += (offset - bv->bv_offset) / sector_sz;
1494 sectors += bv->bv_len / sector_sz;
1499 EXPORT_SYMBOL(bio_sector_offset);
1502 * create memory pools for biovec's in a bio_set.
1503 * use the global biovec slabs created for general use.
1505 static int biovec_create_pools(struct bio_set *bs, int pool_entries)
1507 struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
1509 bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
1516 static void biovec_free_pools(struct bio_set *bs)
1518 mempool_destroy(bs->bvec_pool);
1521 void bioset_free(struct bio_set *bs)
1524 mempool_destroy(bs->bio_pool);
1526 bioset_integrity_free(bs);
1527 biovec_free_pools(bs);
1534 * bioset_create - Create a bio_set
1535 * @pool_size: Number of bio and bio_vecs to cache in the mempool
1536 * @front_pad: Number of bytes to allocate in front of the returned bio
1539 * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1540 * to ask for a number of bytes to be allocated in front of the bio.
1541 * Front pad allocation is useful for embedding the bio inside
1542 * another structure, to avoid allocating extra data to go with the bio.
1543 * Note that the bio must be embedded at the END of that structure always,
1544 * or things will break badly.
1546 struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
1548 unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1551 bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1555 bs->front_pad = front_pad;
1557 bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1558 if (!bs->bio_slab) {
1563 bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
1567 if (bioset_integrity_create(bs, pool_size))
1570 if (!biovec_create_pools(bs, pool_size))
1578 static void __init biovec_init_slabs(void)
1582 for (i = 0; i < BIOVEC_NR_POOLS; i++) {
1584 struct biovec_slab *bvs = bvec_slabs + i;
1586 size = bvs->nr_vecs * sizeof(struct bio_vec);
1587 bvs->slab = kmem_cache_create(bvs->name, size, 0,
1588 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1592 static int __init init_bio(void)
1596 bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
1598 panic("bio: can't allocate bios\n");
1600 bio_integrity_init_slab();
1601 biovec_init_slabs();
1603 fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
1605 panic("bio: can't allocate bios\n");
1607 bio_split_pool = mempool_create_kmalloc_pool(BIO_SPLIT_ENTRIES,
1608 sizeof(struct bio_pair));
1609 if (!bio_split_pool)
1610 panic("bio: can't create split pool\n");
1615 subsys_initcall(init_bio);
1617 EXPORT_SYMBOL(bio_alloc);
1618 EXPORT_SYMBOL(bio_kmalloc);
1619 EXPORT_SYMBOL(bio_put);
1620 EXPORT_SYMBOL(bio_free);
1621 EXPORT_SYMBOL(bio_endio);
1622 EXPORT_SYMBOL(bio_init);
1623 EXPORT_SYMBOL(__bio_clone);
1624 EXPORT_SYMBOL(bio_clone);
1625 EXPORT_SYMBOL(bio_phys_segments);
1626 EXPORT_SYMBOL(bio_add_page);
1627 EXPORT_SYMBOL(bio_add_pc_page);
1628 EXPORT_SYMBOL(bio_get_nr_vecs);
1629 EXPORT_SYMBOL(bio_map_user);
1630 EXPORT_SYMBOL(bio_unmap_user);
1631 EXPORT_SYMBOL(bio_map_kern);
1632 EXPORT_SYMBOL(bio_copy_kern);
1633 EXPORT_SYMBOL(bio_pair_release);
1634 EXPORT_SYMBOL(bio_split);
1635 EXPORT_SYMBOL(bio_copy_user);
1636 EXPORT_SYMBOL(bio_uncopy_user);
1637 EXPORT_SYMBOL(bioset_create);
1638 EXPORT_SYMBOL(bioset_free);
1639 EXPORT_SYMBOL(bio_alloc_bioset);