blob: 249dd6bb66c843ee9e487f124dbe37afab095581 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
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
29#define BIO_POOL_SIZE 256
30
31static kmem_cache_t *bio_slab;
32
33#define BIOVEC_NR_POOLS 6
34
35/*
36 * a small number of entries is fine, not going to be performance critical.
37 * basically we just need to survive
38 */
39#define BIO_SPLIT_ENTRIES 8
40mempool_t *bio_split_pool;
41
42struct biovec_slab {
43 int nr_vecs;
44 char *name;
45 kmem_cache_t *slab;
46};
47
48/*
49 * if you change this list, also change bvec_alloc or things will
50 * break badly! cannot be bigger than what you can fit into an
51 * unsigned short
52 */
53
54#define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
Christoph Lameter6c036522005-07-07 17:56:59 -070055static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
57};
58#undef BV
59
60/*
61 * bio_set is used to allow other portions of the IO system to
62 * allocate their own private memory pools for bio and iovec structures.
63 * These memory pools in turn all allocate from the bio_slab
64 * and the bvec_slabs[].
65 */
66struct bio_set {
67 mempool_t *bio_pool;
68 mempool_t *bvec_pools[BIOVEC_NR_POOLS];
69};
70
71/*
72 * fs_bio_set is the bio_set containing bio and iovec memory pools used by
73 * IO code that does not need private memory pools.
74 */
75static struct bio_set *fs_bio_set;
76
77static inline struct bio_vec *bvec_alloc_bs(unsigned int __nocast gfp_mask, int nr, unsigned long *idx, struct bio_set *bs)
78{
79 struct bio_vec *bvl;
80 struct biovec_slab *bp;
81
82 /*
83 * see comment near bvec_array define!
84 */
85 switch (nr) {
86 case 1 : *idx = 0; break;
87 case 2 ... 4: *idx = 1; break;
88 case 5 ... 16: *idx = 2; break;
89 case 17 ... 64: *idx = 3; break;
90 case 65 ... 128: *idx = 4; break;
91 case 129 ... BIO_MAX_PAGES: *idx = 5; break;
92 default:
93 return NULL;
94 }
95 /*
96 * idx now points to the pool we want to allocate from
97 */
98
99 bp = bvec_slabs + *idx;
100 bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask);
101 if (bvl)
102 memset(bvl, 0, bp->nr_vecs * sizeof(struct bio_vec));
103
104 return bvl;
105}
106
107/*
108 * default destructor for a bio allocated with bio_alloc_bioset()
109 */
110static void bio_destructor(struct bio *bio)
111{
112 const int pool_idx = BIO_POOL_IDX(bio);
113 struct bio_set *bs = bio->bi_set;
114
115 BIO_BUG_ON(pool_idx >= BIOVEC_NR_POOLS);
116
117 mempool_free(bio->bi_io_vec, bs->bvec_pools[pool_idx]);
118 mempool_free(bio, bs->bio_pool);
119}
120
121inline void bio_init(struct bio *bio)
122{
123 bio->bi_next = NULL;
124 bio->bi_flags = 1 << BIO_UPTODATE;
125 bio->bi_rw = 0;
126 bio->bi_vcnt = 0;
127 bio->bi_idx = 0;
128 bio->bi_phys_segments = 0;
129 bio->bi_hw_segments = 0;
130 bio->bi_hw_front_size = 0;
131 bio->bi_hw_back_size = 0;
132 bio->bi_size = 0;
133 bio->bi_max_vecs = 0;
134 bio->bi_end_io = NULL;
135 atomic_set(&bio->bi_cnt, 1);
136 bio->bi_private = NULL;
137}
138
139/**
140 * bio_alloc_bioset - allocate a bio for I/O
141 * @gfp_mask: the GFP_ mask given to the slab allocator
142 * @nr_iovecs: number of iovecs to pre-allocate
Martin Waitz67be2dd2005-05-01 08:59:26 -0700143 * @bs: the bio_set to allocate from
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 *
145 * Description:
146 * bio_alloc_bioset will first try it's on mempool to satisfy the allocation.
147 * If %__GFP_WAIT is set then we will block on the internal pool waiting
148 * for a &struct bio to become free.
149 *
150 * allocate bio and iovecs from the memory pools specified by the
151 * bio_set structure.
152 **/
153struct bio *bio_alloc_bioset(unsigned int __nocast gfp_mask, int nr_iovecs, struct bio_set *bs)
154{
155 struct bio *bio = mempool_alloc(bs->bio_pool, gfp_mask);
156
157 if (likely(bio)) {
158 struct bio_vec *bvl = NULL;
159
160 bio_init(bio);
161 if (likely(nr_iovecs)) {
162 unsigned long idx;
163
164 bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
165 if (unlikely(!bvl)) {
166 mempool_free(bio, bs->bio_pool);
167 bio = NULL;
168 goto out;
169 }
170 bio->bi_flags |= idx << BIO_POOL_OFFSET;
171 bio->bi_max_vecs = bvec_slabs[idx].nr_vecs;
172 }
173 bio->bi_io_vec = bvl;
174 bio->bi_destructor = bio_destructor;
175 bio->bi_set = bs;
176 }
177out:
178 return bio;
179}
180
181struct bio *bio_alloc(unsigned int __nocast gfp_mask, int nr_iovecs)
182{
183 return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
184}
185
186void zero_fill_bio(struct bio *bio)
187{
188 unsigned long flags;
189 struct bio_vec *bv;
190 int i;
191
192 bio_for_each_segment(bv, bio, i) {
193 char *data = bvec_kmap_irq(bv, &flags);
194 memset(data, 0, bv->bv_len);
195 flush_dcache_page(bv->bv_page);
196 bvec_kunmap_irq(data, &flags);
197 }
198}
199EXPORT_SYMBOL(zero_fill_bio);
200
201/**
202 * bio_put - release a reference to a bio
203 * @bio: bio to release reference to
204 *
205 * Description:
206 * Put a reference to a &struct bio, either one you have gotten with
207 * bio_alloc or bio_get. The last put of a bio will free it.
208 **/
209void bio_put(struct bio *bio)
210{
211 BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
212
213 /*
214 * last put frees it
215 */
216 if (atomic_dec_and_test(&bio->bi_cnt)) {
217 bio->bi_next = NULL;
218 bio->bi_destructor(bio);
219 }
220}
221
222inline int bio_phys_segments(request_queue_t *q, struct bio *bio)
223{
224 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
225 blk_recount_segments(q, bio);
226
227 return bio->bi_phys_segments;
228}
229
230inline int bio_hw_segments(request_queue_t *q, struct bio *bio)
231{
232 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
233 blk_recount_segments(q, bio);
234
235 return bio->bi_hw_segments;
236}
237
238/**
239 * __bio_clone - clone a bio
240 * @bio: destination bio
241 * @bio_src: bio to clone
242 *
243 * Clone a &bio. Caller will own the returned bio, but not
244 * the actual data it points to. Reference count of returned
245 * bio will be one.
246 */
247inline void __bio_clone(struct bio *bio, struct bio *bio_src)
248{
249 request_queue_t *q = bdev_get_queue(bio_src->bi_bdev);
250
251 memcpy(bio->bi_io_vec, bio_src->bi_io_vec, bio_src->bi_max_vecs * sizeof(struct bio_vec));
252
253 bio->bi_sector = bio_src->bi_sector;
254 bio->bi_bdev = bio_src->bi_bdev;
255 bio->bi_flags |= 1 << BIO_CLONED;
256 bio->bi_rw = bio_src->bi_rw;
257
258 /*
259 * notes -- maybe just leave bi_idx alone. assume identical mapping
260 * for the clone
261 */
262 bio->bi_vcnt = bio_src->bi_vcnt;
263 bio->bi_size = bio_src->bi_size;
Andrew Mortona5453be2005-07-28 01:07:18 -0700264 bio->bi_idx = bio_src->bi_idx;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 bio_phys_segments(q, bio);
266 bio_hw_segments(q, bio);
267}
268
269/**
270 * bio_clone - clone a bio
271 * @bio: bio to clone
272 * @gfp_mask: allocation priority
273 *
274 * Like __bio_clone, only also allocates the returned bio
275 */
276struct bio *bio_clone(struct bio *bio, unsigned int __nocast gfp_mask)
277{
278 struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set);
279
280 if (b)
281 __bio_clone(b, bio);
282
283 return b;
284}
285
286/**
287 * bio_get_nr_vecs - return approx number of vecs
288 * @bdev: I/O target
289 *
290 * Return the approximate number of pages we can send to this target.
291 * There's no guarantee that you will be able to fit this number of pages
292 * into a bio, it does not account for dynamic restrictions that vary
293 * on offset.
294 */
295int bio_get_nr_vecs(struct block_device *bdev)
296{
297 request_queue_t *q = bdev_get_queue(bdev);
298 int nr_pages;
299
300 nr_pages = ((q->max_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
301 if (nr_pages > q->max_phys_segments)
302 nr_pages = q->max_phys_segments;
303 if (nr_pages > q->max_hw_segments)
304 nr_pages = q->max_hw_segments;
305
306 return nr_pages;
307}
308
309static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
310 *page, unsigned int len, unsigned int offset)
311{
312 int retried_segments = 0;
313 struct bio_vec *bvec;
314
315 /*
316 * cloned bio must not modify vec list
317 */
318 if (unlikely(bio_flagged(bio, BIO_CLONED)))
319 return 0;
320
321 if (bio->bi_vcnt >= bio->bi_max_vecs)
322 return 0;
323
324 if (((bio->bi_size + len) >> 9) > q->max_sectors)
325 return 0;
326
327 /*
328 * we might lose a segment or two here, but rather that than
329 * make this too complex.
330 */
331
332 while (bio->bi_phys_segments >= q->max_phys_segments
333 || bio->bi_hw_segments >= q->max_hw_segments
334 || BIOVEC_VIRT_OVERSIZE(bio->bi_size)) {
335
336 if (retried_segments)
337 return 0;
338
339 retried_segments = 1;
340 blk_recount_segments(q, bio);
341 }
342
343 /*
344 * setup the new entry, we might clear it again later if we
345 * cannot add the page
346 */
347 bvec = &bio->bi_io_vec[bio->bi_vcnt];
348 bvec->bv_page = page;
349 bvec->bv_len = len;
350 bvec->bv_offset = offset;
351
352 /*
353 * if queue has other restrictions (eg varying max sector size
354 * depending on offset), it can specify a merge_bvec_fn in the
355 * queue to get further control
356 */
357 if (q->merge_bvec_fn) {
358 /*
359 * merge_bvec_fn() returns number of bytes it can accept
360 * at this offset
361 */
362 if (q->merge_bvec_fn(q, bio, bvec) < len) {
363 bvec->bv_page = NULL;
364 bvec->bv_len = 0;
365 bvec->bv_offset = 0;
366 return 0;
367 }
368 }
369
370 /* If we may be able to merge these biovecs, force a recount */
371 if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec) ||
372 BIOVEC_VIRT_MERGEABLE(bvec-1, bvec)))
373 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
374
375 bio->bi_vcnt++;
376 bio->bi_phys_segments++;
377 bio->bi_hw_segments++;
378 bio->bi_size += len;
379 return len;
380}
381
382/**
383 * bio_add_page - attempt to add page to bio
384 * @bio: destination bio
385 * @page: page to add
386 * @len: vec entry length
387 * @offset: vec entry offset
388 *
389 * Attempt to add a page to the bio_vec maplist. This can fail for a
390 * number of reasons, such as the bio being full or target block
391 * device limitations. The target block device must allow bio's
392 * smaller than PAGE_SIZE, so it is always possible to add a single
393 * page to an empty bio.
394 */
395int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
396 unsigned int offset)
397{
398 return __bio_add_page(bdev_get_queue(bio->bi_bdev), bio, page,
399 len, offset);
400}
401
402struct bio_map_data {
403 struct bio_vec *iovecs;
404 void __user *userptr;
405};
406
407static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio)
408{
409 memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
410 bio->bi_private = bmd;
411}
412
413static void bio_free_map_data(struct bio_map_data *bmd)
414{
415 kfree(bmd->iovecs);
416 kfree(bmd);
417}
418
419static struct bio_map_data *bio_alloc_map_data(int nr_segs)
420{
421 struct bio_map_data *bmd = kmalloc(sizeof(*bmd), GFP_KERNEL);
422
423 if (!bmd)
424 return NULL;
425
426 bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, GFP_KERNEL);
427 if (bmd->iovecs)
428 return bmd;
429
430 kfree(bmd);
431 return NULL;
432}
433
434/**
435 * bio_uncopy_user - finish previously mapped bio
436 * @bio: bio being terminated
437 *
438 * Free pages allocated from bio_copy_user() and write back data
439 * to user space in case of a read.
440 */
441int bio_uncopy_user(struct bio *bio)
442{
443 struct bio_map_data *bmd = bio->bi_private;
444 const int read = bio_data_dir(bio) == READ;
445 struct bio_vec *bvec;
446 int i, ret = 0;
447
448 __bio_for_each_segment(bvec, bio, i, 0) {
449 char *addr = page_address(bvec->bv_page);
450 unsigned int len = bmd->iovecs[i].bv_len;
451
452 if (read && !ret && copy_to_user(bmd->userptr, addr, len))
453 ret = -EFAULT;
454
455 __free_page(bvec->bv_page);
456 bmd->userptr += len;
457 }
458 bio_free_map_data(bmd);
459 bio_put(bio);
460 return ret;
461}
462
463/**
464 * bio_copy_user - copy user data to bio
465 * @q: destination block queue
466 * @uaddr: start of user address
467 * @len: length in bytes
468 * @write_to_vm: bool indicating writing to pages or not
469 *
470 * Prepares and returns a bio for indirect user io, bouncing data
471 * to/from kernel pages as necessary. Must be paired with
472 * call bio_uncopy_user() on io completion.
473 */
474struct bio *bio_copy_user(request_queue_t *q, unsigned long uaddr,
475 unsigned int len, int write_to_vm)
476{
477 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
478 unsigned long start = uaddr >> PAGE_SHIFT;
479 struct bio_map_data *bmd;
480 struct bio_vec *bvec;
481 struct page *page;
482 struct bio *bio;
483 int i, ret;
484
485 bmd = bio_alloc_map_data(end - start);
486 if (!bmd)
487 return ERR_PTR(-ENOMEM);
488
489 bmd->userptr = (void __user *) uaddr;
490
491 ret = -ENOMEM;
492 bio = bio_alloc(GFP_KERNEL, end - start);
493 if (!bio)
494 goto out_bmd;
495
496 bio->bi_rw |= (!write_to_vm << BIO_RW);
497
498 ret = 0;
499 while (len) {
500 unsigned int bytes = PAGE_SIZE;
501
502 if (bytes > len)
503 bytes = len;
504
505 page = alloc_page(q->bounce_gfp | GFP_KERNEL);
506 if (!page) {
507 ret = -ENOMEM;
508 break;
509 }
510
511 if (__bio_add_page(q, bio, page, bytes, 0) < bytes) {
512 ret = -EINVAL;
513 break;
514 }
515
516 len -= bytes;
517 }
518
519 if (ret)
520 goto cleanup;
521
522 /*
523 * success
524 */
525 if (!write_to_vm) {
526 char __user *p = (char __user *) uaddr;
527
528 /*
529 * for a write, copy in data to kernel pages
530 */
531 ret = -EFAULT;
532 bio_for_each_segment(bvec, bio, i) {
533 char *addr = page_address(bvec->bv_page);
534
535 if (copy_from_user(addr, p, bvec->bv_len))
536 goto cleanup;
537 p += bvec->bv_len;
538 }
539 }
540
541 bio_set_map_data(bmd, bio);
542 return bio;
543cleanup:
544 bio_for_each_segment(bvec, bio, i)
545 __free_page(bvec->bv_page);
546
547 bio_put(bio);
548out_bmd:
549 bio_free_map_data(bmd);
550 return ERR_PTR(ret);
551}
552
553static struct bio *__bio_map_user(request_queue_t *q, struct block_device *bdev,
554 unsigned long uaddr, unsigned int len,
555 int write_to_vm)
556{
557 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
558 unsigned long start = uaddr >> PAGE_SHIFT;
559 const int nr_pages = end - start;
560 int ret, offset, i;
561 struct page **pages;
562 struct bio *bio;
563
564 /*
565 * transfer and buffer must be aligned to at least hardsector
566 * size for now, in the future we can relax this restriction
567 */
568 if ((uaddr & queue_dma_alignment(q)) || (len & queue_dma_alignment(q)))
569 return ERR_PTR(-EINVAL);
570
571 bio = bio_alloc(GFP_KERNEL, nr_pages);
572 if (!bio)
573 return ERR_PTR(-ENOMEM);
574
575 ret = -ENOMEM;
576 pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
577 if (!pages)
578 goto out;
579
580 down_read(&current->mm->mmap_sem);
581 ret = get_user_pages(current, current->mm, uaddr, nr_pages,
582 write_to_vm, 0, pages, NULL);
583 up_read(&current->mm->mmap_sem);
584
585 if (ret < nr_pages)
586 goto out;
587
588 bio->bi_bdev = bdev;
589
590 offset = uaddr & ~PAGE_MASK;
591 for (i = 0; i < nr_pages; i++) {
592 unsigned int bytes = PAGE_SIZE - offset;
593
594 if (len <= 0)
595 break;
596
597 if (bytes > len)
598 bytes = len;
599
600 /*
601 * sorry...
602 */
603 if (__bio_add_page(q, bio, pages[i], bytes, offset) < bytes)
604 break;
605
606 len -= bytes;
607 offset = 0;
608 }
609
610 /*
611 * release the pages we didn't map into the bio, if any
612 */
613 while (i < nr_pages)
614 page_cache_release(pages[i++]);
615
616 kfree(pages);
617
618 /*
619 * set data direction, and check if mapped pages need bouncing
620 */
621 if (!write_to_vm)
622 bio->bi_rw |= (1 << BIO_RW);
623
624 bio->bi_flags |= (1 << BIO_USER_MAPPED);
625 return bio;
626out:
627 kfree(pages);
628 bio_put(bio);
629 return ERR_PTR(ret);
630}
631
632/**
633 * bio_map_user - map user address into bio
Martin Waitz67be2dd2005-05-01 08:59:26 -0700634 * @q: the request_queue_t for the bio
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 * @bdev: destination block device
636 * @uaddr: start of user address
637 * @len: length in bytes
638 * @write_to_vm: bool indicating writing to pages or not
639 *
640 * Map the user space address into a bio suitable for io to a block
641 * device. Returns an error pointer in case of error.
642 */
643struct bio *bio_map_user(request_queue_t *q, struct block_device *bdev,
644 unsigned long uaddr, unsigned int len, int write_to_vm)
645{
646 struct bio *bio;
647
648 bio = __bio_map_user(q, bdev, uaddr, len, write_to_vm);
649
650 if (IS_ERR(bio))
651 return bio;
652
653 /*
654 * subtle -- if __bio_map_user() ended up bouncing a bio,
655 * it would normally disappear when its bi_end_io is run.
656 * however, we need it for the unmap, so grab an extra
657 * reference to it
658 */
659 bio_get(bio);
660
661 if (bio->bi_size == len)
662 return bio;
663
664 /*
665 * don't support partial mappings
666 */
667 bio_endio(bio, bio->bi_size, 0);
668 bio_unmap_user(bio);
669 return ERR_PTR(-EINVAL);
670}
671
672static void __bio_unmap_user(struct bio *bio)
673{
674 struct bio_vec *bvec;
675 int i;
676
677 /*
678 * make sure we dirty pages we wrote to
679 */
680 __bio_for_each_segment(bvec, bio, i, 0) {
681 if (bio_data_dir(bio) == READ)
682 set_page_dirty_lock(bvec->bv_page);
683
684 page_cache_release(bvec->bv_page);
685 }
686
687 bio_put(bio);
688}
689
690/**
691 * bio_unmap_user - unmap a bio
692 * @bio: the bio being unmapped
693 *
694 * Unmap a bio previously mapped by bio_map_user(). Must be called with
695 * a process context.
696 *
697 * bio_unmap_user() may sleep.
698 */
699void bio_unmap_user(struct bio *bio)
700{
701 __bio_unmap_user(bio);
702 bio_put(bio);
703}
704
705/*
706 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
707 * for performing direct-IO in BIOs.
708 *
709 * The problem is that we cannot run set_page_dirty() from interrupt context
710 * because the required locks are not interrupt-safe. So what we can do is to
711 * mark the pages dirty _before_ performing IO. And in interrupt context,
712 * check that the pages are still dirty. If so, fine. If not, redirty them
713 * in process context.
714 *
715 * We special-case compound pages here: normally this means reads into hugetlb
716 * pages. The logic in here doesn't really work right for compound pages
717 * because the VM does not uniformly chase down the head page in all cases.
718 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
719 * handle them at all. So we skip compound pages here at an early stage.
720 *
721 * Note that this code is very hard to test under normal circumstances because
722 * direct-io pins the pages with get_user_pages(). This makes
723 * is_page_cache_freeable return false, and the VM will not clean the pages.
724 * But other code (eg, pdflush) could clean the pages if they are mapped
725 * pagecache.
726 *
727 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
728 * deferred bio dirtying paths.
729 */
730
731/*
732 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
733 */
734void bio_set_pages_dirty(struct bio *bio)
735{
736 struct bio_vec *bvec = bio->bi_io_vec;
737 int i;
738
739 for (i = 0; i < bio->bi_vcnt; i++) {
740 struct page *page = bvec[i].bv_page;
741
742 if (page && !PageCompound(page))
743 set_page_dirty_lock(page);
744 }
745}
746
747static void bio_release_pages(struct bio *bio)
748{
749 struct bio_vec *bvec = bio->bi_io_vec;
750 int i;
751
752 for (i = 0; i < bio->bi_vcnt; i++) {
753 struct page *page = bvec[i].bv_page;
754
755 if (page)
756 put_page(page);
757 }
758}
759
760/*
761 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
762 * If they are, then fine. If, however, some pages are clean then they must
763 * have been written out during the direct-IO read. So we take another ref on
764 * the BIO and the offending pages and re-dirty the pages in process context.
765 *
766 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
767 * here on. It will run one page_cache_release() against each page and will
768 * run one bio_put() against the BIO.
769 */
770
771static void bio_dirty_fn(void *data);
772
773static DECLARE_WORK(bio_dirty_work, bio_dirty_fn, NULL);
774static DEFINE_SPINLOCK(bio_dirty_lock);
775static struct bio *bio_dirty_list;
776
777/*
778 * This runs in process context
779 */
780static void bio_dirty_fn(void *data)
781{
782 unsigned long flags;
783 struct bio *bio;
784
785 spin_lock_irqsave(&bio_dirty_lock, flags);
786 bio = bio_dirty_list;
787 bio_dirty_list = NULL;
788 spin_unlock_irqrestore(&bio_dirty_lock, flags);
789
790 while (bio) {
791 struct bio *next = bio->bi_private;
792
793 bio_set_pages_dirty(bio);
794 bio_release_pages(bio);
795 bio_put(bio);
796 bio = next;
797 }
798}
799
800void bio_check_pages_dirty(struct bio *bio)
801{
802 struct bio_vec *bvec = bio->bi_io_vec;
803 int nr_clean_pages = 0;
804 int i;
805
806 for (i = 0; i < bio->bi_vcnt; i++) {
807 struct page *page = bvec[i].bv_page;
808
809 if (PageDirty(page) || PageCompound(page)) {
810 page_cache_release(page);
811 bvec[i].bv_page = NULL;
812 } else {
813 nr_clean_pages++;
814 }
815 }
816
817 if (nr_clean_pages) {
818 unsigned long flags;
819
820 spin_lock_irqsave(&bio_dirty_lock, flags);
821 bio->bi_private = bio_dirty_list;
822 bio_dirty_list = bio;
823 spin_unlock_irqrestore(&bio_dirty_lock, flags);
824 schedule_work(&bio_dirty_work);
825 } else {
826 bio_put(bio);
827 }
828}
829
830/**
831 * bio_endio - end I/O on a bio
832 * @bio: bio
833 * @bytes_done: number of bytes completed
834 * @error: error, if any
835 *
836 * Description:
837 * bio_endio() will end I/O on @bytes_done number of bytes. This may be
838 * just a partial part of the bio, or it may be the whole bio. bio_endio()
839 * is the preferred way to end I/O on a bio, it takes care of decrementing
840 * bi_size and clearing BIO_UPTODATE on error. @error is 0 on success, and
841 * and one of the established -Exxxx (-EIO, for instance) error values in
842 * case something went wrong. Noone should call bi_end_io() directly on
843 * a bio unless they own it and thus know that it has an end_io function.
844 **/
845void bio_endio(struct bio *bio, unsigned int bytes_done, int error)
846{
847 if (error)
848 clear_bit(BIO_UPTODATE, &bio->bi_flags);
849
850 if (unlikely(bytes_done > bio->bi_size)) {
851 printk("%s: want %u bytes done, only %u left\n", __FUNCTION__,
852 bytes_done, bio->bi_size);
853 bytes_done = bio->bi_size;
854 }
855
856 bio->bi_size -= bytes_done;
857 bio->bi_sector += (bytes_done >> 9);
858
859 if (bio->bi_end_io)
860 bio->bi_end_io(bio, bytes_done, error);
861}
862
863void bio_pair_release(struct bio_pair *bp)
864{
865 if (atomic_dec_and_test(&bp->cnt)) {
866 struct bio *master = bp->bio1.bi_private;
867
868 bio_endio(master, master->bi_size, bp->error);
869 mempool_free(bp, bp->bio2.bi_private);
870 }
871}
872
873static int bio_pair_end_1(struct bio * bi, unsigned int done, int err)
874{
875 struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
876
877 if (err)
878 bp->error = err;
879
880 if (bi->bi_size)
881 return 1;
882
883 bio_pair_release(bp);
884 return 0;
885}
886
887static int bio_pair_end_2(struct bio * bi, unsigned int done, int err)
888{
889 struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
890
891 if (err)
892 bp->error = err;
893
894 if (bi->bi_size)
895 return 1;
896
897 bio_pair_release(bp);
898 return 0;
899}
900
901/*
902 * split a bio - only worry about a bio with a single page
903 * in it's iovec
904 */
905struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, int first_sectors)
906{
907 struct bio_pair *bp = mempool_alloc(pool, GFP_NOIO);
908
909 if (!bp)
910 return bp;
911
912 BUG_ON(bi->bi_vcnt != 1);
913 BUG_ON(bi->bi_idx != 0);
914 atomic_set(&bp->cnt, 3);
915 bp->error = 0;
916 bp->bio1 = *bi;
917 bp->bio2 = *bi;
918 bp->bio2.bi_sector += first_sectors;
919 bp->bio2.bi_size -= first_sectors << 9;
920 bp->bio1.bi_size = first_sectors << 9;
921
922 bp->bv1 = bi->bi_io_vec[0];
923 bp->bv2 = bi->bi_io_vec[0];
924 bp->bv2.bv_offset += first_sectors << 9;
925 bp->bv2.bv_len -= first_sectors << 9;
926 bp->bv1.bv_len = first_sectors << 9;
927
928 bp->bio1.bi_io_vec = &bp->bv1;
929 bp->bio2.bi_io_vec = &bp->bv2;
930
931 bp->bio1.bi_end_io = bio_pair_end_1;
932 bp->bio2.bi_end_io = bio_pair_end_2;
933
934 bp->bio1.bi_private = bi;
935 bp->bio2.bi_private = pool;
936
937 return bp;
938}
939
940static void *bio_pair_alloc(unsigned int __nocast gfp_flags, void *data)
941{
942 return kmalloc(sizeof(struct bio_pair), gfp_flags);
943}
944
945static void bio_pair_free(void *bp, void *data)
946{
947 kfree(bp);
948}
949
950
951/*
952 * create memory pools for biovec's in a bio_set.
953 * use the global biovec slabs created for general use.
954 */
955static int biovec_create_pools(struct bio_set *bs, int pool_entries, int scale)
956{
957 int i;
958
959 for (i = 0; i < BIOVEC_NR_POOLS; i++) {
960 struct biovec_slab *bp = bvec_slabs + i;
961 mempool_t **bvp = bs->bvec_pools + i;
962
963 if (i >= scale)
964 pool_entries >>= 1;
965
966 *bvp = mempool_create(pool_entries, mempool_alloc_slab,
967 mempool_free_slab, bp->slab);
968 if (!*bvp)
969 return -ENOMEM;
970 }
971 return 0;
972}
973
974static void biovec_free_pools(struct bio_set *bs)
975{
976 int i;
977
978 for (i = 0; i < BIOVEC_NR_POOLS; i++) {
979 mempool_t *bvp = bs->bvec_pools[i];
980
981 if (bvp)
982 mempool_destroy(bvp);
983 }
984
985}
986
987void bioset_free(struct bio_set *bs)
988{
989 if (bs->bio_pool)
990 mempool_destroy(bs->bio_pool);
991
992 biovec_free_pools(bs);
993
994 kfree(bs);
995}
996
997struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size, int scale)
998{
999 struct bio_set *bs = kmalloc(sizeof(*bs), GFP_KERNEL);
1000
1001 if (!bs)
1002 return NULL;
1003
1004 memset(bs, 0, sizeof(*bs));
1005 bs->bio_pool = mempool_create(bio_pool_size, mempool_alloc_slab,
1006 mempool_free_slab, bio_slab);
1007
1008 if (!bs->bio_pool)
1009 goto bad;
1010
1011 if (!biovec_create_pools(bs, bvec_pool_size, scale))
1012 return bs;
1013
1014bad:
1015 bioset_free(bs);
1016 return NULL;
1017}
1018
1019static void __init biovec_init_slabs(void)
1020{
1021 int i;
1022
1023 for (i = 0; i < BIOVEC_NR_POOLS; i++) {
1024 int size;
1025 struct biovec_slab *bvs = bvec_slabs + i;
1026
1027 size = bvs->nr_vecs * sizeof(struct bio_vec);
1028 bvs->slab = kmem_cache_create(bvs->name, size, 0,
1029 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1030 }
1031}
1032
1033static int __init init_bio(void)
1034{
1035 int megabytes, bvec_pool_entries;
1036 int scale = BIOVEC_NR_POOLS;
1037
1038 bio_slab = kmem_cache_create("bio", sizeof(struct bio), 0,
1039 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1040
1041 biovec_init_slabs();
1042
1043 megabytes = nr_free_pages() >> (20 - PAGE_SHIFT);
1044
1045 /*
1046 * find out where to start scaling
1047 */
1048 if (megabytes <= 16)
1049 scale = 0;
1050 else if (megabytes <= 32)
1051 scale = 1;
1052 else if (megabytes <= 64)
1053 scale = 2;
1054 else if (megabytes <= 96)
1055 scale = 3;
1056 else if (megabytes <= 128)
1057 scale = 4;
1058
1059 /*
1060 * scale number of entries
1061 */
1062 bvec_pool_entries = megabytes * 2;
1063 if (bvec_pool_entries > 256)
1064 bvec_pool_entries = 256;
1065
1066 fs_bio_set = bioset_create(BIO_POOL_SIZE, bvec_pool_entries, scale);
1067 if (!fs_bio_set)
1068 panic("bio: can't allocate bios\n");
1069
1070 bio_split_pool = mempool_create(BIO_SPLIT_ENTRIES,
1071 bio_pair_alloc, bio_pair_free, NULL);
1072 if (!bio_split_pool)
1073 panic("bio: can't create split pool\n");
1074
1075 return 0;
1076}
1077
1078subsys_initcall(init_bio);
1079
1080EXPORT_SYMBOL(bio_alloc);
1081EXPORT_SYMBOL(bio_put);
1082EXPORT_SYMBOL(bio_endio);
1083EXPORT_SYMBOL(bio_init);
1084EXPORT_SYMBOL(__bio_clone);
1085EXPORT_SYMBOL(bio_clone);
1086EXPORT_SYMBOL(bio_phys_segments);
1087EXPORT_SYMBOL(bio_hw_segments);
1088EXPORT_SYMBOL(bio_add_page);
1089EXPORT_SYMBOL(bio_get_nr_vecs);
1090EXPORT_SYMBOL(bio_map_user);
1091EXPORT_SYMBOL(bio_unmap_user);
1092EXPORT_SYMBOL(bio_pair_release);
1093EXPORT_SYMBOL(bio_split);
1094EXPORT_SYMBOL(bio_split_pool);
1095EXPORT_SYMBOL(bio_copy_user);
1096EXPORT_SYMBOL(bio_uncopy_user);
1097EXPORT_SYMBOL(bioset_create);
1098EXPORT_SYMBOL(bioset_free);
1099EXPORT_SYMBOL(bio_alloc_bioset);