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/uio.h>
23 #include <linux/iocontext.h>
24 #include <linux/slab.h>
25 #include <linux/init.h>
26 #include <linux/kernel.h>
27 #include <linux/export.h>
28 #include <linux/mempool.h>
29 #include <linux/workqueue.h>
30 #include <linux/cgroup.h>
32 #include <trace/events/block.h>
36 * Test patch to inline a certain number of bi_io_vec's inside the bio
37 * itself, to shrink a bio data allocation from two mempool calls to one
39 #define BIO_INLINE_VECS 4
42 * if you change this list, also change bvec_alloc or things will
43 * break badly! cannot be bigger than what you can fit into an
46 #define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n }
47 static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = {
48 BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max),
53 * fs_bio_set is the bio_set containing bio and iovec memory pools used by
54 * IO code that does not need private memory pools.
56 struct bio_set *fs_bio_set;
57 EXPORT_SYMBOL(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, *new_bio_slabs;
77 unsigned int new_bio_slab_max;
78 unsigned int i, entry = -1;
80 mutex_lock(&bio_slab_lock);
83 while (i < bio_slab_nr) {
84 bslab = &bio_slabs[i];
86 if (!bslab->slab && entry == -1)
88 else if (bslab->slab_size == sz) {
99 if (bio_slab_nr == bio_slab_max && entry == -1) {
100 new_bio_slab_max = bio_slab_max << 1;
101 new_bio_slabs = krealloc(bio_slabs,
102 new_bio_slab_max * sizeof(struct bio_slab),
106 bio_slab_max = new_bio_slab_max;
107 bio_slabs = new_bio_slabs;
110 entry = bio_slab_nr++;
112 bslab = &bio_slabs[entry];
114 snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
115 slab = kmem_cache_create(bslab->name, sz, ARCH_KMALLOC_MINALIGN,
116 SLAB_HWCACHE_ALIGN, NULL);
122 bslab->slab_size = sz;
124 mutex_unlock(&bio_slab_lock);
128 static void bio_put_slab(struct bio_set *bs)
130 struct bio_slab *bslab = NULL;
133 mutex_lock(&bio_slab_lock);
135 for (i = 0; i < bio_slab_nr; i++) {
136 if (bs->bio_slab == bio_slabs[i].slab) {
137 bslab = &bio_slabs[i];
142 if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
145 WARN_ON(!bslab->slab_ref);
147 if (--bslab->slab_ref)
150 kmem_cache_destroy(bslab->slab);
154 mutex_unlock(&bio_slab_lock);
157 unsigned int bvec_nr_vecs(unsigned short idx)
159 return bvec_slabs[idx].nr_vecs;
162 void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
168 BIO_BUG_ON(idx >= BVEC_POOL_NR);
170 if (idx == BVEC_POOL_MAX) {
171 mempool_free(bv, pool);
173 struct biovec_slab *bvs = bvec_slabs + idx;
175 kmem_cache_free(bvs->slab, bv);
179 struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
185 * see comment near bvec_array define!
203 case 129 ... BIO_MAX_PAGES:
211 * idx now points to the pool we want to allocate from. only the
212 * 1-vec entry pool is mempool backed.
214 if (*idx == BVEC_POOL_MAX) {
216 bvl = mempool_alloc(pool, gfp_mask);
218 struct biovec_slab *bvs = bvec_slabs + *idx;
219 gfp_t __gfp_mask = gfp_mask & ~(__GFP_DIRECT_RECLAIM | __GFP_IO);
222 * Make this allocation restricted and don't dump info on
223 * allocation failures, since we'll fallback to the mempool
224 * in case of failure.
226 __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
229 * Try a slab allocation. If this fails and __GFP_DIRECT_RECLAIM
230 * is set, retry with the 1-entry mempool
232 bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
233 if (unlikely(!bvl && (gfp_mask & __GFP_DIRECT_RECLAIM))) {
234 *idx = BVEC_POOL_MAX;
243 void bio_uninit(struct bio *bio)
245 bio_disassociate_task(bio);
247 EXPORT_SYMBOL(bio_uninit);
249 static void bio_free(struct bio *bio)
251 struct bio_set *bs = bio->bi_pool;
257 bvec_free(bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio));
260 * If we have front padding, adjust the bio pointer before freeing
265 mempool_free(p, bs->bio_pool);
267 /* Bio was allocated by bio_kmalloc() */
273 * Users of this function have their own bio allocation. Subsequently,
274 * they must remember to pair any call to bio_init() with bio_uninit()
275 * when IO has completed, or when the bio is released.
277 void bio_init(struct bio *bio, struct bio_vec *table,
278 unsigned short max_vecs)
280 memset(bio, 0, sizeof(*bio));
281 atomic_set(&bio->__bi_remaining, 1);
282 atomic_set(&bio->__bi_cnt, 1);
284 bio->bi_io_vec = table;
285 bio->bi_max_vecs = max_vecs;
287 EXPORT_SYMBOL(bio_init);
290 * bio_reset - reinitialize a bio
294 * After calling bio_reset(), @bio will be in the same state as a freshly
295 * allocated bio returned bio bio_alloc_bioset() - the only fields that are
296 * preserved are the ones that are initialized by bio_alloc_bioset(). See
297 * comment in struct bio.
299 void bio_reset(struct bio *bio)
301 unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
305 memset(bio, 0, BIO_RESET_BYTES);
306 bio->bi_flags = flags;
307 atomic_set(&bio->__bi_remaining, 1);
309 EXPORT_SYMBOL(bio_reset);
311 static struct bio *__bio_chain_endio(struct bio *bio)
313 struct bio *parent = bio->bi_private;
315 if (!parent->bi_status)
316 parent->bi_status = bio->bi_status;
321 static void bio_chain_endio(struct bio *bio)
323 bio_endio(__bio_chain_endio(bio));
327 * bio_chain - chain bio completions
328 * @bio: the target bio
329 * @parent: the @bio's parent bio
331 * The caller won't have a bi_end_io called when @bio completes - instead,
332 * @parent's bi_end_io won't be called until both @parent and @bio have
333 * completed; the chained bio will also be freed when it completes.
335 * The caller must not set bi_private or bi_end_io in @bio.
337 void bio_chain(struct bio *bio, struct bio *parent)
339 BUG_ON(bio->bi_private || bio->bi_end_io);
341 bio->bi_private = parent;
342 bio->bi_end_io = bio_chain_endio;
343 bio_inc_remaining(parent);
345 EXPORT_SYMBOL(bio_chain);
347 static void bio_alloc_rescue(struct work_struct *work)
349 struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
353 spin_lock(&bs->rescue_lock);
354 bio = bio_list_pop(&bs->rescue_list);
355 spin_unlock(&bs->rescue_lock);
360 generic_make_request(bio);
364 static void punt_bios_to_rescuer(struct bio_set *bs)
366 struct bio_list punt, nopunt;
369 if (WARN_ON_ONCE(!bs->rescue_workqueue))
372 * In order to guarantee forward progress we must punt only bios that
373 * were allocated from this bio_set; otherwise, if there was a bio on
374 * there for a stacking driver higher up in the stack, processing it
375 * could require allocating bios from this bio_set, and doing that from
376 * our own rescuer would be bad.
378 * Since bio lists are singly linked, pop them all instead of trying to
379 * remove from the middle of the list:
382 bio_list_init(&punt);
383 bio_list_init(&nopunt);
385 while ((bio = bio_list_pop(¤t->bio_list[0])))
386 bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
387 current->bio_list[0] = nopunt;
389 bio_list_init(&nopunt);
390 while ((bio = bio_list_pop(¤t->bio_list[1])))
391 bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
392 current->bio_list[1] = nopunt;
394 spin_lock(&bs->rescue_lock);
395 bio_list_merge(&bs->rescue_list, &punt);
396 spin_unlock(&bs->rescue_lock);
398 queue_work(bs->rescue_workqueue, &bs->rescue_work);
402 * bio_alloc_bioset - allocate a bio for I/O
403 * @gfp_mask: the GFP_ mask given to the slab allocator
404 * @nr_iovecs: number of iovecs to pre-allocate
405 * @bs: the bio_set to allocate from.
408 * If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
409 * backed by the @bs's mempool.
411 * When @bs is not NULL, if %__GFP_DIRECT_RECLAIM is set then bio_alloc will
412 * always be able to allocate a bio. This is due to the mempool guarantees.
413 * To make this work, callers must never allocate more than 1 bio at a time
414 * from this pool. Callers that need to allocate more than 1 bio must always
415 * submit the previously allocated bio for IO before attempting to allocate
416 * a new one. Failure to do so can cause deadlocks under memory pressure.
418 * Note that when running under generic_make_request() (i.e. any block
419 * driver), bios are not submitted until after you return - see the code in
420 * generic_make_request() that converts recursion into iteration, to prevent
423 * This would normally mean allocating multiple bios under
424 * generic_make_request() would be susceptible to deadlocks, but we have
425 * deadlock avoidance code that resubmits any blocked bios from a rescuer
428 * However, we do not guarantee forward progress for allocations from other
429 * mempools. Doing multiple allocations from the same mempool under
430 * generic_make_request() should be avoided - instead, use bio_set's front_pad
431 * for per bio allocations.
434 * Pointer to new bio on success, NULL on failure.
436 struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
439 gfp_t saved_gfp = gfp_mask;
441 unsigned inline_vecs;
442 struct bio_vec *bvl = NULL;
447 if (nr_iovecs > UIO_MAXIOV)
450 p = kmalloc(sizeof(struct bio) +
451 nr_iovecs * sizeof(struct bio_vec),
454 inline_vecs = nr_iovecs;
456 /* should not use nobvec bioset for nr_iovecs > 0 */
457 if (WARN_ON_ONCE(!bs->bvec_pool && nr_iovecs > 0))
460 * generic_make_request() converts recursion to iteration; this
461 * means if we're running beneath it, any bios we allocate and
462 * submit will not be submitted (and thus freed) until after we
465 * This exposes us to a potential deadlock if we allocate
466 * multiple bios from the same bio_set() while running
467 * underneath generic_make_request(). If we were to allocate
468 * multiple bios (say a stacking block driver that was splitting
469 * bios), we would deadlock if we exhausted the mempool's
472 * We solve this, and guarantee forward progress, with a rescuer
473 * workqueue per bio_set. If we go to allocate and there are
474 * bios on current->bio_list, we first try the allocation
475 * without __GFP_DIRECT_RECLAIM; if that fails, we punt those
476 * bios we would be blocking to the rescuer workqueue before
477 * we retry with the original gfp_flags.
480 if (current->bio_list &&
481 (!bio_list_empty(¤t->bio_list[0]) ||
482 !bio_list_empty(¤t->bio_list[1])) &&
483 bs->rescue_workqueue)
484 gfp_mask &= ~__GFP_DIRECT_RECLAIM;
486 p = mempool_alloc(bs->bio_pool, gfp_mask);
487 if (!p && gfp_mask != saved_gfp) {
488 punt_bios_to_rescuer(bs);
489 gfp_mask = saved_gfp;
490 p = mempool_alloc(bs->bio_pool, gfp_mask);
493 front_pad = bs->front_pad;
494 inline_vecs = BIO_INLINE_VECS;
501 bio_init(bio, NULL, 0);
503 if (nr_iovecs > inline_vecs) {
504 unsigned long idx = 0;
506 bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
507 if (!bvl && gfp_mask != saved_gfp) {
508 punt_bios_to_rescuer(bs);
509 gfp_mask = saved_gfp;
510 bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
516 bio->bi_flags |= idx << BVEC_POOL_OFFSET;
517 } else if (nr_iovecs) {
518 bvl = bio->bi_inline_vecs;
522 bio->bi_max_vecs = nr_iovecs;
523 bio->bi_io_vec = bvl;
527 mempool_free(p, bs->bio_pool);
530 EXPORT_SYMBOL(bio_alloc_bioset);
532 void zero_fill_bio(struct bio *bio)
536 struct bvec_iter iter;
538 bio_for_each_segment(bv, bio, iter) {
539 char *data = bvec_kmap_irq(&bv, &flags);
540 memset(data, 0, bv.bv_len);
541 flush_dcache_page(bv.bv_page);
542 bvec_kunmap_irq(data, &flags);
545 EXPORT_SYMBOL(zero_fill_bio);
548 * bio_put - release a reference to a bio
549 * @bio: bio to release reference to
552 * Put a reference to a &struct bio, either one you have gotten with
553 * bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it.
555 void bio_put(struct bio *bio)
557 if (!bio_flagged(bio, BIO_REFFED))
560 BIO_BUG_ON(!atomic_read(&bio->__bi_cnt));
565 if (atomic_dec_and_test(&bio->__bi_cnt))
569 EXPORT_SYMBOL(bio_put);
571 inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
573 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
574 blk_recount_segments(q, bio);
576 return bio->bi_phys_segments;
578 EXPORT_SYMBOL(bio_phys_segments);
581 * __bio_clone_fast - clone a bio that shares the original bio's biovec
582 * @bio: destination bio
583 * @bio_src: bio to clone
585 * Clone a &bio. Caller will own the returned bio, but not
586 * the actual data it points to. Reference count of returned
589 * Caller must ensure that @bio_src is not freed before @bio.
591 void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
593 BUG_ON(bio->bi_pool && BVEC_POOL_IDX(bio));
596 * most users will be overriding ->bi_disk with a new target,
597 * so we don't set nor calculate new physical/hw segment counts here
599 bio->bi_disk = bio_src->bi_disk;
600 bio->bi_partno = bio_src->bi_partno;
601 bio_set_flag(bio, BIO_CLONED);
602 if (bio_flagged(bio_src, BIO_THROTTLED))
603 bio_set_flag(bio, BIO_THROTTLED);
604 bio->bi_opf = bio_src->bi_opf;
605 bio->bi_write_hint = bio_src->bi_write_hint;
606 bio->bi_iter = bio_src->bi_iter;
607 bio->bi_io_vec = bio_src->bi_io_vec;
609 bio_clone_blkcg_association(bio, bio_src);
611 EXPORT_SYMBOL(__bio_clone_fast);
614 * bio_clone_fast - clone a bio that shares the original bio's biovec
616 * @gfp_mask: allocation priority
617 * @bs: bio_set to allocate from
619 * Like __bio_clone_fast, only also allocates the returned bio
621 struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
625 b = bio_alloc_bioset(gfp_mask, 0, bs);
629 __bio_clone_fast(b, bio);
631 if (bio_integrity(bio)) {
634 ret = bio_integrity_clone(b, bio, gfp_mask);
644 EXPORT_SYMBOL(bio_clone_fast);
647 * bio_clone_bioset - clone a bio
648 * @bio_src: bio to clone
649 * @gfp_mask: allocation priority
650 * @bs: bio_set to allocate from
652 * Clone bio. Caller will own the returned bio, but not the actual data it
653 * points to. Reference count of returned bio will be one.
655 struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
658 struct bvec_iter iter;
663 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
664 * bio_src->bi_io_vec to bio->bi_io_vec.
666 * We can't do that anymore, because:
668 * - The point of cloning the biovec is to produce a bio with a biovec
669 * the caller can modify: bi_idx and bi_bvec_done should be 0.
671 * - The original bio could've had more than BIO_MAX_PAGES biovecs; if
672 * we tried to clone the whole thing bio_alloc_bioset() would fail.
673 * But the clone should succeed as long as the number of biovecs we
674 * actually need to allocate is fewer than BIO_MAX_PAGES.
676 * - Lastly, bi_vcnt should not be looked at or relied upon by code
677 * that does not own the bio - reason being drivers don't use it for
678 * iterating over the biovec anymore, so expecting it to be kept up
679 * to date (i.e. for clones that share the parent biovec) is just
680 * asking for trouble and would force extra work on
681 * __bio_clone_fast() anyways.
684 bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
687 bio->bi_disk = bio_src->bi_disk;
688 bio->bi_opf = bio_src->bi_opf;
689 bio->bi_write_hint = bio_src->bi_write_hint;
690 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
691 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
693 switch (bio_op(bio)) {
695 case REQ_OP_SECURE_ERASE:
696 case REQ_OP_WRITE_ZEROES:
698 case REQ_OP_WRITE_SAME:
699 bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
702 bio_for_each_segment(bv, bio_src, iter)
703 bio->bi_io_vec[bio->bi_vcnt++] = bv;
707 if (bio_integrity(bio_src)) {
710 ret = bio_integrity_clone(bio, bio_src, gfp_mask);
717 bio_clone_blkcg_association(bio, bio_src);
721 EXPORT_SYMBOL(bio_clone_bioset);
724 * bio_add_pc_page - attempt to add page to bio
725 * @q: the target queue
726 * @bio: destination bio
728 * @len: vec entry length
729 * @offset: vec entry offset
731 * Attempt to add a page to the bio_vec maplist. This can fail for a
732 * number of reasons, such as the bio being full or target block device
733 * limitations. The target block device must allow bio's up to PAGE_SIZE,
734 * so it is always possible to add a single page to an empty bio.
736 * This should only be used by REQ_PC bios.
738 int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page
739 *page, unsigned int len, unsigned int offset)
741 int retried_segments = 0;
742 struct bio_vec *bvec;
745 * cloned bio must not modify vec list
747 if (unlikely(bio_flagged(bio, BIO_CLONED)))
750 if (((bio->bi_iter.bi_size + len) >> 9) > queue_max_hw_sectors(q))
754 * For filesystems with a blocksize smaller than the pagesize
755 * we will often be called with the same page as last time and
756 * a consecutive offset. Optimize this special case.
758 if (bio->bi_vcnt > 0) {
759 struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
761 if (page == prev->bv_page &&
762 offset == prev->bv_offset + prev->bv_len) {
764 bio->bi_iter.bi_size += len;
769 * If the queue doesn't support SG gaps and adding this
770 * offset would create a gap, disallow it.
772 if (bvec_gap_to_prev(q, prev, offset))
776 if (bio->bi_vcnt >= bio->bi_max_vecs)
780 * setup the new entry, we might clear it again later if we
781 * cannot add the page
783 bvec = &bio->bi_io_vec[bio->bi_vcnt];
784 bvec->bv_page = page;
786 bvec->bv_offset = offset;
788 bio->bi_phys_segments++;
789 bio->bi_iter.bi_size += len;
792 * Perform a recount if the number of segments is greater
793 * than queue_max_segments(q).
796 while (bio->bi_phys_segments > queue_max_segments(q)) {
798 if (retried_segments)
801 retried_segments = 1;
802 blk_recount_segments(q, bio);
805 /* If we may be able to merge these biovecs, force a recount */
806 if (bio->bi_vcnt > 1 && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
807 bio_clear_flag(bio, BIO_SEG_VALID);
813 bvec->bv_page = NULL;
817 bio->bi_iter.bi_size -= len;
818 blk_recount_segments(q, bio);
821 EXPORT_SYMBOL(bio_add_pc_page);
824 * bio_add_page - attempt to add page to bio
825 * @bio: destination bio
827 * @len: vec entry length
828 * @offset: vec entry offset
830 * Attempt to add a page to the bio_vec maplist. This will only fail
831 * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio.
833 int bio_add_page(struct bio *bio, struct page *page,
834 unsigned int len, unsigned int offset)
839 * cloned bio must not modify vec list
841 if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
845 * For filesystems with a blocksize smaller than the pagesize
846 * we will often be called with the same page as last time and
847 * a consecutive offset. Optimize this special case.
849 if (bio->bi_vcnt > 0) {
850 bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
852 if (page == bv->bv_page &&
853 offset == bv->bv_offset + bv->bv_len) {
859 if (bio->bi_vcnt >= bio->bi_max_vecs)
862 bv = &bio->bi_io_vec[bio->bi_vcnt];
865 bv->bv_offset = offset;
869 bio->bi_iter.bi_size += len;
872 EXPORT_SYMBOL(bio_add_page);
875 * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
876 * @bio: bio to add pages to
877 * @iter: iov iterator describing the region to be mapped
879 * Pins as many pages from *iter and appends them to @bio's bvec array. The
880 * pages will have to be released using put_page() when done.
882 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
884 unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt, idx;
885 struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
886 struct page **pages = (struct page **)bv;
890 size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
891 if (unlikely(size <= 0))
892 return size ? size : -EFAULT;
893 idx = nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE;
896 * Deep magic below: We need to walk the pinned pages backwards
897 * because we are abusing the space allocated for the bio_vecs
898 * for the page array. Because the bio_vecs are larger than the
899 * page pointers by definition this will always work. But it also
900 * means we can't use bio_add_page, so any changes to it's semantics
901 * need to be reflected here as well.
903 bio->bi_iter.bi_size += size;
904 bio->bi_vcnt += nr_pages;
907 bv[idx].bv_page = pages[idx];
908 bv[idx].bv_len = PAGE_SIZE;
909 bv[idx].bv_offset = 0;
912 bv[0].bv_offset += offset;
913 bv[0].bv_len -= offset;
914 bv[nr_pages - 1].bv_len -= nr_pages * PAGE_SIZE - offset - size;
916 iov_iter_advance(iter, size);
919 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
921 struct submit_bio_ret {
922 struct completion event;
926 static void submit_bio_wait_endio(struct bio *bio)
928 struct submit_bio_ret *ret = bio->bi_private;
930 ret->error = blk_status_to_errno(bio->bi_status);
931 complete(&ret->event);
935 * submit_bio_wait - submit a bio, and wait until it completes
936 * @bio: The &struct bio which describes the I/O
938 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from
939 * bio_endio() on failure.
941 * WARNING: Unlike to how submit_bio() is usually used, this function does not
942 * result in bio reference to be consumed. The caller must drop the reference
945 int submit_bio_wait(struct bio *bio)
947 struct submit_bio_ret ret;
949 init_completion(&ret.event);
950 bio->bi_private = &ret;
951 bio->bi_end_io = submit_bio_wait_endio;
952 bio->bi_opf |= REQ_SYNC;
954 wait_for_completion_io(&ret.event);
958 EXPORT_SYMBOL(submit_bio_wait);
961 * bio_advance - increment/complete a bio by some number of bytes
962 * @bio: bio to advance
963 * @bytes: number of bytes to complete
965 * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
966 * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
967 * be updated on the last bvec as well.
969 * @bio will then represent the remaining, uncompleted portion of the io.
971 void bio_advance(struct bio *bio, unsigned bytes)
973 if (bio_integrity(bio))
974 bio_integrity_advance(bio, bytes);
976 bio_advance_iter(bio, &bio->bi_iter, bytes);
978 EXPORT_SYMBOL(bio_advance);
981 * bio_alloc_pages - allocates a single page for each bvec in a bio
982 * @bio: bio to allocate pages for
983 * @gfp_mask: flags for allocation
985 * Allocates pages up to @bio->bi_vcnt.
987 * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
990 int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
995 bio_for_each_segment_all(bv, bio, i) {
996 bv->bv_page = alloc_page(gfp_mask);
998 while (--bv >= bio->bi_io_vec)
999 __free_page(bv->bv_page);
1006 EXPORT_SYMBOL(bio_alloc_pages);
1009 * bio_copy_data - copy contents of data buffers from one chain of bios to
1011 * @src: source bio list
1012 * @dst: destination bio list
1014 * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats
1015 * @src and @dst as linked lists of bios.
1017 * Stops when it reaches the end of either @src or @dst - that is, copies
1018 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
1020 void bio_copy_data(struct bio *dst, struct bio *src)
1022 struct bvec_iter src_iter, dst_iter;
1023 struct bio_vec src_bv, dst_bv;
1024 void *src_p, *dst_p;
1027 src_iter = src->bi_iter;
1028 dst_iter = dst->bi_iter;
1031 if (!src_iter.bi_size) {
1036 src_iter = src->bi_iter;
1039 if (!dst_iter.bi_size) {
1044 dst_iter = dst->bi_iter;
1047 src_bv = bio_iter_iovec(src, src_iter);
1048 dst_bv = bio_iter_iovec(dst, dst_iter);
1050 bytes = min(src_bv.bv_len, dst_bv.bv_len);
1052 src_p = kmap_atomic(src_bv.bv_page);
1053 dst_p = kmap_atomic(dst_bv.bv_page);
1055 memcpy(dst_p + dst_bv.bv_offset,
1056 src_p + src_bv.bv_offset,
1059 kunmap_atomic(dst_p);
1060 kunmap_atomic(src_p);
1062 bio_advance_iter(src, &src_iter, bytes);
1063 bio_advance_iter(dst, &dst_iter, bytes);
1066 EXPORT_SYMBOL(bio_copy_data);
1068 struct bio_map_data {
1070 struct iov_iter iter;
1074 static struct bio_map_data *bio_alloc_map_data(unsigned int iov_count,
1077 if (iov_count > UIO_MAXIOV)
1080 return kmalloc(sizeof(struct bio_map_data) +
1081 sizeof(struct iovec) * iov_count, gfp_mask);
1085 * bio_copy_from_iter - copy all pages from iov_iter to bio
1086 * @bio: The &struct bio which describes the I/O as destination
1087 * @iter: iov_iter as source
1089 * Copy all pages from iov_iter to bio.
1090 * Returns 0 on success, or error on failure.
1092 static int bio_copy_from_iter(struct bio *bio, struct iov_iter iter)
1095 struct bio_vec *bvec;
1097 bio_for_each_segment_all(bvec, bio, i) {
1100 ret = copy_page_from_iter(bvec->bv_page,
1105 if (!iov_iter_count(&iter))
1108 if (ret < bvec->bv_len)
1116 * bio_copy_to_iter - copy all pages from bio to iov_iter
1117 * @bio: The &struct bio which describes the I/O as source
1118 * @iter: iov_iter as destination
1120 * Copy all pages from bio to iov_iter.
1121 * Returns 0 on success, or error on failure.
1123 static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter)
1126 struct bio_vec *bvec;
1128 bio_for_each_segment_all(bvec, bio, i) {
1131 ret = copy_page_to_iter(bvec->bv_page,
1136 if (!iov_iter_count(&iter))
1139 if (ret < bvec->bv_len)
1146 void bio_free_pages(struct bio *bio)
1148 struct bio_vec *bvec;
1151 bio_for_each_segment_all(bvec, bio, i)
1152 __free_page(bvec->bv_page);
1154 EXPORT_SYMBOL(bio_free_pages);
1157 * bio_uncopy_user - finish previously mapped bio
1158 * @bio: bio being terminated
1160 * Free pages allocated from bio_copy_user_iov() and write back data
1161 * to user space in case of a read.
1163 int bio_uncopy_user(struct bio *bio)
1165 struct bio_map_data *bmd = bio->bi_private;
1168 if (!bio_flagged(bio, BIO_NULL_MAPPED)) {
1170 * if we're in a workqueue, the request is orphaned, so
1171 * don't copy into a random user address space, just free
1172 * and return -EINTR so user space doesn't expect any data.
1176 else if (bio_data_dir(bio) == READ)
1177 ret = bio_copy_to_iter(bio, bmd->iter);
1178 if (bmd->is_our_pages)
1179 bio_free_pages(bio);
1187 * bio_copy_user_iov - copy user data to bio
1188 * @q: destination block queue
1189 * @map_data: pointer to the rq_map_data holding pages (if necessary)
1190 * @iter: iovec iterator
1191 * @gfp_mask: memory allocation flags
1193 * Prepares and returns a bio for indirect user io, bouncing data
1194 * to/from kernel pages as necessary. Must be paired with
1195 * call bio_uncopy_user() on io completion.
1197 struct bio *bio_copy_user_iov(struct request_queue *q,
1198 struct rq_map_data *map_data,
1199 const struct iov_iter *iter,
1202 struct bio_map_data *bmd;
1207 unsigned int len = iter->count;
1208 unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0;
1210 for (i = 0; i < iter->nr_segs; i++) {
1211 unsigned long uaddr;
1213 unsigned long start;
1215 uaddr = (unsigned long) iter->iov[i].iov_base;
1216 end = (uaddr + iter->iov[i].iov_len + PAGE_SIZE - 1)
1218 start = uaddr >> PAGE_SHIFT;
1224 return ERR_PTR(-EINVAL);
1226 nr_pages += end - start;
1232 bmd = bio_alloc_map_data(iter->nr_segs, gfp_mask);
1234 return ERR_PTR(-ENOMEM);
1237 * We need to do a deep copy of the iov_iter including the iovecs.
1238 * The caller provided iov might point to an on-stack or otherwise
1241 bmd->is_our_pages = map_data ? 0 : 1;
1242 memcpy(bmd->iov, iter->iov, sizeof(struct iovec) * iter->nr_segs);
1244 bmd->iter.iov = bmd->iov;
1247 bio = bio_kmalloc(gfp_mask, nr_pages);
1254 nr_pages = 1 << map_data->page_order;
1255 i = map_data->offset / PAGE_SIZE;
1258 unsigned int bytes = PAGE_SIZE;
1266 if (i == map_data->nr_entries * nr_pages) {
1271 page = map_data->pages[i / nr_pages];
1272 page += (i % nr_pages);
1276 page = alloc_page(q->bounce_gfp | gfp_mask);
1283 if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
1296 if (((iter->type & WRITE) && (!map_data || !map_data->null_mapped)) ||
1297 (map_data && map_data->from_user)) {
1298 ret = bio_copy_from_iter(bio, *iter);
1303 bio->bi_private = bmd;
1307 bio_free_pages(bio);
1311 return ERR_PTR(ret);
1315 * bio_map_user_iov - map user iovec into bio
1316 * @q: the struct request_queue for the bio
1317 * @iter: iovec iterator
1318 * @gfp_mask: memory allocation flags
1320 * Map the user space address into a bio suitable for io to a block
1321 * device. Returns an error pointer in case of error.
1323 struct bio *bio_map_user_iov(struct request_queue *q,
1324 const struct iov_iter *iter,
1329 struct page **pages;
1335 struct bio_vec *bvec;
1337 iov_for_each(iov, i, *iter) {
1338 unsigned long uaddr = (unsigned long) iov.iov_base;
1339 unsigned long len = iov.iov_len;
1340 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1341 unsigned long start = uaddr >> PAGE_SHIFT;
1347 return ERR_PTR(-EINVAL);
1349 nr_pages += end - start;
1351 * buffer must be aligned to at least logical block size for now
1353 if (uaddr & queue_dma_alignment(q))
1354 return ERR_PTR(-EINVAL);
1358 return ERR_PTR(-EINVAL);
1360 bio = bio_kmalloc(gfp_mask, nr_pages);
1362 return ERR_PTR(-ENOMEM);
1365 pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
1369 iov_for_each(iov, i, *iter) {
1370 unsigned long uaddr = (unsigned long) iov.iov_base;
1371 unsigned long len = iov.iov_len;
1372 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1373 unsigned long start = uaddr >> PAGE_SHIFT;
1374 const int local_nr_pages = end - start;
1375 const int page_limit = cur_page + local_nr_pages;
1377 ret = get_user_pages_fast(uaddr, local_nr_pages,
1378 (iter->type & WRITE) != WRITE,
1380 if (unlikely(ret < local_nr_pages)) {
1381 for (j = cur_page; j < page_limit; j++) {
1390 offset = offset_in_page(uaddr);
1391 for (j = cur_page; j < page_limit; j++) {
1392 unsigned int bytes = PAGE_SIZE - offset;
1393 unsigned short prev_bi_vcnt = bio->bi_vcnt;
1404 if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
1409 * check if vector was merged with previous
1410 * drop page reference if needed
1412 if (bio->bi_vcnt == prev_bi_vcnt)
1421 * release the pages we didn't map into the bio, if any
1423 while (j < page_limit)
1424 put_page(pages[j++]);
1429 bio_set_flag(bio, BIO_USER_MAPPED);
1432 * subtle -- if bio_map_user_iov() ended up bouncing a bio,
1433 * it would normally disappear when its bi_end_io is run.
1434 * however, we need it for the unmap, so grab an extra
1441 bio_for_each_segment_all(bvec, bio, j) {
1442 put_page(bvec->bv_page);
1447 return ERR_PTR(ret);
1450 static void __bio_unmap_user(struct bio *bio)
1452 struct bio_vec *bvec;
1456 * make sure we dirty pages we wrote to
1458 bio_for_each_segment_all(bvec, bio, i) {
1459 if (bio_data_dir(bio) == READ)
1460 set_page_dirty_lock(bvec->bv_page);
1462 put_page(bvec->bv_page);
1469 * bio_unmap_user - unmap a bio
1470 * @bio: the bio being unmapped
1472 * Unmap a bio previously mapped by bio_map_user_iov(). Must be called from
1475 * bio_unmap_user() may sleep.
1477 void bio_unmap_user(struct bio *bio)
1479 __bio_unmap_user(bio);
1483 static void bio_map_kern_endio(struct bio *bio)
1489 * bio_map_kern - map kernel address into bio
1490 * @q: the struct request_queue for the bio
1491 * @data: pointer to buffer to map
1492 * @len: length in bytes
1493 * @gfp_mask: allocation flags for bio allocation
1495 * Map the kernel address into a bio suitable for io to a block
1496 * device. Returns an error pointer in case of error.
1498 struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1501 unsigned long kaddr = (unsigned long)data;
1502 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1503 unsigned long start = kaddr >> PAGE_SHIFT;
1504 const int nr_pages = end - start;
1508 bio = bio_kmalloc(gfp_mask, nr_pages);
1510 return ERR_PTR(-ENOMEM);
1512 offset = offset_in_page(kaddr);
1513 for (i = 0; i < nr_pages; i++) {
1514 unsigned int bytes = PAGE_SIZE - offset;
1522 if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1524 /* we don't support partial mappings */
1526 return ERR_PTR(-EINVAL);
1534 bio->bi_end_io = bio_map_kern_endio;
1537 EXPORT_SYMBOL(bio_map_kern);
1539 static void bio_copy_kern_endio(struct bio *bio)
1541 bio_free_pages(bio);
1545 static void bio_copy_kern_endio_read(struct bio *bio)
1547 char *p = bio->bi_private;
1548 struct bio_vec *bvec;
1551 bio_for_each_segment_all(bvec, bio, i) {
1552 memcpy(p, page_address(bvec->bv_page), bvec->bv_len);
1556 bio_copy_kern_endio(bio);
1560 * bio_copy_kern - copy kernel address into bio
1561 * @q: the struct request_queue for the bio
1562 * @data: pointer to buffer to copy
1563 * @len: length in bytes
1564 * @gfp_mask: allocation flags for bio and page allocation
1565 * @reading: data direction is READ
1567 * copy the kernel address into a bio suitable for io to a block
1568 * device. Returns an error pointer in case of error.
1570 struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1571 gfp_t gfp_mask, int reading)
1573 unsigned long kaddr = (unsigned long)data;
1574 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1575 unsigned long start = kaddr >> PAGE_SHIFT;
1584 return ERR_PTR(-EINVAL);
1586 nr_pages = end - start;
1587 bio = bio_kmalloc(gfp_mask, nr_pages);
1589 return ERR_PTR(-ENOMEM);
1593 unsigned int bytes = PAGE_SIZE;
1598 page = alloc_page(q->bounce_gfp | gfp_mask);
1603 memcpy(page_address(page), p, bytes);
1605 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
1613 bio->bi_end_io = bio_copy_kern_endio_read;
1614 bio->bi_private = data;
1616 bio->bi_end_io = bio_copy_kern_endio;
1622 bio_free_pages(bio);
1624 return ERR_PTR(-ENOMEM);
1628 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1629 * for performing direct-IO in BIOs.
1631 * The problem is that we cannot run set_page_dirty() from interrupt context
1632 * because the required locks are not interrupt-safe. So what we can do is to
1633 * mark the pages dirty _before_ performing IO. And in interrupt context,
1634 * check that the pages are still dirty. If so, fine. If not, redirty them
1635 * in process context.
1637 * We special-case compound pages here: normally this means reads into hugetlb
1638 * pages. The logic in here doesn't really work right for compound pages
1639 * because the VM does not uniformly chase down the head page in all cases.
1640 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1641 * handle them at all. So we skip compound pages here at an early stage.
1643 * Note that this code is very hard to test under normal circumstances because
1644 * direct-io pins the pages with get_user_pages(). This makes
1645 * is_page_cache_freeable return false, and the VM will not clean the pages.
1646 * But other code (eg, flusher threads) could clean the pages if they are mapped
1649 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1650 * deferred bio dirtying paths.
1654 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1656 void bio_set_pages_dirty(struct bio *bio)
1658 struct bio_vec *bvec;
1661 bio_for_each_segment_all(bvec, bio, i) {
1662 struct page *page = bvec->bv_page;
1664 if (page && !PageCompound(page))
1665 set_page_dirty_lock(page);
1669 static void bio_release_pages(struct bio *bio)
1671 struct bio_vec *bvec;
1674 bio_for_each_segment_all(bvec, bio, i) {
1675 struct page *page = bvec->bv_page;
1683 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1684 * If they are, then fine. If, however, some pages are clean then they must
1685 * have been written out during the direct-IO read. So we take another ref on
1686 * the BIO and the offending pages and re-dirty the pages in process context.
1688 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1689 * here on. It will run one put_page() against each page and will run one
1690 * bio_put() against the BIO.
1693 static void bio_dirty_fn(struct work_struct *work);
1695 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1696 static DEFINE_SPINLOCK(bio_dirty_lock);
1697 static struct bio *bio_dirty_list;
1700 * This runs in process context
1702 static void bio_dirty_fn(struct work_struct *work)
1704 unsigned long flags;
1707 spin_lock_irqsave(&bio_dirty_lock, flags);
1708 bio = bio_dirty_list;
1709 bio_dirty_list = NULL;
1710 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1713 struct bio *next = bio->bi_private;
1715 bio_set_pages_dirty(bio);
1716 bio_release_pages(bio);
1722 void bio_check_pages_dirty(struct bio *bio)
1724 struct bio_vec *bvec;
1725 int nr_clean_pages = 0;
1728 bio_for_each_segment_all(bvec, bio, i) {
1729 struct page *page = bvec->bv_page;
1731 if (PageDirty(page) || PageCompound(page)) {
1733 bvec->bv_page = NULL;
1739 if (nr_clean_pages) {
1740 unsigned long flags;
1742 spin_lock_irqsave(&bio_dirty_lock, flags);
1743 bio->bi_private = bio_dirty_list;
1744 bio_dirty_list = bio;
1745 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1746 schedule_work(&bio_dirty_work);
1752 void generic_start_io_acct(struct request_queue *q, int rw,
1753 unsigned long sectors, struct hd_struct *part)
1755 int cpu = part_stat_lock();
1757 part_round_stats(q, cpu, part);
1758 part_stat_inc(cpu, part, ios[rw]);
1759 part_stat_add(cpu, part, sectors[rw], sectors);
1760 part_inc_in_flight(q, part, rw);
1764 EXPORT_SYMBOL(generic_start_io_acct);
1766 void generic_end_io_acct(struct request_queue *q, int rw,
1767 struct hd_struct *part, unsigned long start_time)
1769 unsigned long duration = jiffies - start_time;
1770 int cpu = part_stat_lock();
1772 part_stat_add(cpu, part, ticks[rw], duration);
1773 part_round_stats(q, cpu, part);
1774 part_dec_in_flight(q, part, rw);
1778 EXPORT_SYMBOL(generic_end_io_acct);
1780 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1781 void bio_flush_dcache_pages(struct bio *bi)
1783 struct bio_vec bvec;
1784 struct bvec_iter iter;
1786 bio_for_each_segment(bvec, bi, iter)
1787 flush_dcache_page(bvec.bv_page);
1789 EXPORT_SYMBOL(bio_flush_dcache_pages);
1792 static inline bool bio_remaining_done(struct bio *bio)
1795 * If we're not chaining, then ->__bi_remaining is always 1 and
1796 * we always end io on the first invocation.
1798 if (!bio_flagged(bio, BIO_CHAIN))
1801 BUG_ON(atomic_read(&bio->__bi_remaining) <= 0);
1803 if (atomic_dec_and_test(&bio->__bi_remaining)) {
1804 bio_clear_flag(bio, BIO_CHAIN);
1812 * bio_endio - end I/O on a bio
1816 * bio_endio() will end I/O on the whole bio. bio_endio() is the preferred
1817 * way to end I/O on a bio. No one should call bi_end_io() directly on a
1818 * bio unless they own it and thus know that it has an end_io function.
1820 * bio_endio() can be called several times on a bio that has been chained
1821 * using bio_chain(). The ->bi_end_io() function will only be called the
1822 * last time. At this point the BLK_TA_COMPLETE tracing event will be
1823 * generated if BIO_TRACE_COMPLETION is set.
1825 void bio_endio(struct bio *bio)
1828 if (!bio_remaining_done(bio))
1830 if (!bio_integrity_endio(bio))
1834 * Need to have a real endio function for chained bios, otherwise
1835 * various corner cases will break (like stacking block devices that
1836 * save/restore bi_end_io) - however, we want to avoid unbounded
1837 * recursion and blowing the stack. Tail call optimization would
1838 * handle this, but compiling with frame pointers also disables
1839 * gcc's sibling call optimization.
1841 if (bio->bi_end_io == bio_chain_endio) {
1842 bio = __bio_chain_endio(bio);
1846 if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
1847 trace_block_bio_complete(bio->bi_disk->queue, bio,
1848 blk_status_to_errno(bio->bi_status));
1849 bio_clear_flag(bio, BIO_TRACE_COMPLETION);
1852 blk_throtl_bio_endio(bio);
1853 /* release cgroup info */
1856 bio->bi_end_io(bio);
1858 EXPORT_SYMBOL(bio_endio);
1861 * bio_split - split a bio
1862 * @bio: bio to split
1863 * @sectors: number of sectors to split from the front of @bio
1865 * @bs: bio set to allocate from
1867 * Allocates and returns a new bio which represents @sectors from the start of
1868 * @bio, and updates @bio to represent the remaining sectors.
1870 * Unless this is a discard request the newly allocated bio will point
1871 * to @bio's bi_io_vec; it is the caller's responsibility to ensure that
1872 * @bio is not freed before the split.
1874 struct bio *bio_split(struct bio *bio, int sectors,
1875 gfp_t gfp, struct bio_set *bs)
1877 struct bio *split = NULL;
1879 BUG_ON(sectors <= 0);
1880 BUG_ON(sectors >= bio_sectors(bio));
1882 split = bio_clone_fast(bio, gfp, bs);
1886 split->bi_iter.bi_size = sectors << 9;
1888 if (bio_integrity(split))
1889 bio_integrity_trim(split);
1891 bio_advance(bio, split->bi_iter.bi_size);
1893 if (bio_flagged(bio, BIO_TRACE_COMPLETION))
1894 bio_set_flag(split, BIO_TRACE_COMPLETION);
1898 EXPORT_SYMBOL(bio_split);
1901 * bio_trim - trim a bio
1903 * @offset: number of sectors to trim from the front of @bio
1904 * @size: size we want to trim @bio to, in sectors
1906 void bio_trim(struct bio *bio, int offset, int size)
1908 /* 'bio' is a cloned bio which we need to trim to match
1909 * the given offset and size.
1913 if (offset == 0 && size == bio->bi_iter.bi_size)
1916 bio_clear_flag(bio, BIO_SEG_VALID);
1918 bio_advance(bio, offset << 9);
1920 bio->bi_iter.bi_size = size;
1922 if (bio_integrity(bio))
1923 bio_integrity_trim(bio);
1926 EXPORT_SYMBOL_GPL(bio_trim);
1929 * create memory pools for biovec's in a bio_set.
1930 * use the global biovec slabs created for general use.
1932 mempool_t *biovec_create_pool(int pool_entries)
1934 struct biovec_slab *bp = bvec_slabs + BVEC_POOL_MAX;
1936 return mempool_create_slab_pool(pool_entries, bp->slab);
1939 void bioset_free(struct bio_set *bs)
1941 if (bs->rescue_workqueue)
1942 destroy_workqueue(bs->rescue_workqueue);
1945 mempool_destroy(bs->bio_pool);
1948 mempool_destroy(bs->bvec_pool);
1950 bioset_integrity_free(bs);
1955 EXPORT_SYMBOL(bioset_free);
1958 * bioset_create - Create a bio_set
1959 * @pool_size: Number of bio and bio_vecs to cache in the mempool
1960 * @front_pad: Number of bytes to allocate in front of the returned bio
1961 * @flags: Flags to modify behavior, currently %BIOSET_NEED_BVECS
1962 * and %BIOSET_NEED_RESCUER
1965 * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1966 * to ask for a number of bytes to be allocated in front of the bio.
1967 * Front pad allocation is useful for embedding the bio inside
1968 * another structure, to avoid allocating extra data to go with the bio.
1969 * Note that the bio must be embedded at the END of that structure always,
1970 * or things will break badly.
1971 * If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
1972 * for allocating iovecs. This pool is not needed e.g. for bio_clone_fast().
1973 * If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used to
1974 * dispatch queued requests when the mempool runs out of space.
1977 struct bio_set *bioset_create(unsigned int pool_size,
1978 unsigned int front_pad,
1981 unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1984 bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1988 bs->front_pad = front_pad;
1990 spin_lock_init(&bs->rescue_lock);
1991 bio_list_init(&bs->rescue_list);
1992 INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
1994 bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1995 if (!bs->bio_slab) {
2000 bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
2004 if (flags & BIOSET_NEED_BVECS) {
2005 bs->bvec_pool = biovec_create_pool(pool_size);
2010 if (!(flags & BIOSET_NEED_RESCUER))
2013 bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
2014 if (!bs->rescue_workqueue)
2022 EXPORT_SYMBOL(bioset_create);
2024 #ifdef CONFIG_BLK_CGROUP
2027 * bio_associate_blkcg - associate a bio with the specified blkcg
2029 * @blkcg_css: css of the blkcg to associate
2031 * Associate @bio with the blkcg specified by @blkcg_css. Block layer will
2032 * treat @bio as if it were issued by a task which belongs to the blkcg.
2034 * This function takes an extra reference of @blkcg_css which will be put
2035 * when @bio is released. The caller must own @bio and is responsible for
2036 * synchronizing calls to this function.
2038 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)
2040 if (unlikely(bio->bi_css))
2043 bio->bi_css = blkcg_css;
2046 EXPORT_SYMBOL_GPL(bio_associate_blkcg);
2049 * bio_associate_current - associate a bio with %current
2052 * Associate @bio with %current if it hasn't been associated yet. Block
2053 * layer will treat @bio as if it were issued by %current no matter which
2054 * task actually issues it.
2056 * This function takes an extra reference of @task's io_context and blkcg
2057 * which will be put when @bio is released. The caller must own @bio,
2058 * ensure %current->io_context exists, and is responsible for synchronizing
2059 * calls to this function.
2061 int bio_associate_current(struct bio *bio)
2063 struct io_context *ioc;
2068 ioc = current->io_context;
2072 get_io_context_active(ioc);
2074 bio->bi_css = task_get_css(current, io_cgrp_id);
2077 EXPORT_SYMBOL_GPL(bio_associate_current);
2080 * bio_disassociate_task - undo bio_associate_current()
2083 void bio_disassociate_task(struct bio *bio)
2086 put_io_context(bio->bi_ioc);
2090 css_put(bio->bi_css);
2096 * bio_clone_blkcg_association - clone blkcg association from src to dst bio
2097 * @dst: destination bio
2100 void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
2103 WARN_ON(bio_associate_blkcg(dst, src->bi_css));
2105 EXPORT_SYMBOL_GPL(bio_clone_blkcg_association);
2106 #endif /* CONFIG_BLK_CGROUP */
2108 static void __init biovec_init_slabs(void)
2112 for (i = 0; i < BVEC_POOL_NR; i++) {
2114 struct biovec_slab *bvs = bvec_slabs + i;
2116 if (bvs->nr_vecs <= BIO_INLINE_VECS) {
2121 size = bvs->nr_vecs * sizeof(struct bio_vec);
2122 bvs->slab = kmem_cache_create(bvs->name, size, 0,
2123 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2127 static int __init init_bio(void)
2131 bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
2133 panic("bio: can't allocate bios\n");
2135 bio_integrity_init();
2136 biovec_init_slabs();
2138 fs_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
2140 panic("bio: can't allocate bios\n");
2142 if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
2143 panic("bio: can't create integrity pool\n");
2147 subsys_initcall(init_bio);