1 /*
2 * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public Licens
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
16 *
17 */
18 #include <linux/mm.h>
19 #include <linux/swap.h>
20 #include <linux/bio.h>
21 #include <linux/blkdev.h>
22 #include <linux/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>
31 #include <scsi/sg.h> /* for struct sg_iovec */
32
33 #include <trace/events/block.h>
34
35 /*
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
38 */
39 #define BIO_INLINE_VECS 4
40
41 /*
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
44 * unsigned short
45 */
46 #define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
47 static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
48 BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
49 };
50 #undef BV
51
52 /*
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.
55 */
56 struct bio_set *fs_bio_set;
57 EXPORT_SYMBOL(fs_bio_set);
58
59 /*
60 * Our slab pool management
61 */
62 struct bio_slab {
63 struct kmem_cache *slab;
64 unsigned int slab_ref;
65 unsigned int slab_size;
66 char name[8];
67 };
68 static DEFINE_MUTEX(bio_slab_lock);
69 static struct bio_slab *bio_slabs;
70 static unsigned int bio_slab_nr, bio_slab_max;
71
72 static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
73 {
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;
79
80 mutex_lock(&bio_slab_lock);
81
82 i = 0;
83 while (i < bio_slab_nr) {
84 bslab = &bio_slabs[i];
85
86 if (!bslab->slab && entry == -1)
87 entry = i;
88 else if (bslab->slab_size == sz) {
89 slab = bslab->slab;
90 bslab->slab_ref++;
91 break;
92 }
93 i++;
94 }
95
96 if (slab)
97 goto out_unlock;
98
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),
103 GFP_KERNEL);
104 if (!new_bio_slabs)
105 goto out_unlock;
106 bio_slab_max = new_bio_slab_max;
107 bio_slabs = new_bio_slabs;
108 }
109 if (entry == -1)
110 entry = bio_slab_nr++;
111
112 bslab = &bio_slabs[entry];
113
114 snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
115 slab = kmem_cache_create(bslab->name, sz, 0, SLAB_HWCACHE_ALIGN, NULL);
116 if (!slab)
117 goto out_unlock;
118
119 bslab->slab = slab;
120 bslab->slab_ref = 1;
121 bslab->slab_size = sz;
122 out_unlock:
123 mutex_unlock(&bio_slab_lock);
124 return slab;
125 }
126
127 static void bio_put_slab(struct bio_set *bs)
128 {
129 struct bio_slab *bslab = NULL;
130 unsigned int i;
131
132 mutex_lock(&bio_slab_lock);
133
134 for (i = 0; i < bio_slab_nr; i++) {
135 if (bs->bio_slab == bio_slabs[i].slab) {
136 bslab = &bio_slabs[i];
137 break;
138 }
139 }
140
141 if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
142 goto out;
143
144 WARN_ON(!bslab->slab_ref);
145
146 if (--bslab->slab_ref)
147 goto out;
148
149 kmem_cache_destroy(bslab->slab);
150 bslab->slab = NULL;
151
152 out:
153 mutex_unlock(&bio_slab_lock);
154 }
155
156 unsigned int bvec_nr_vecs(unsigned short idx)
157 {
158 return bvec_slabs[idx].nr_vecs;
159 }
160
161 void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
162 {
163 BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
164
165 if (idx == BIOVEC_MAX_IDX)
166 mempool_free(bv, pool);
167 else {
168 struct biovec_slab *bvs = bvec_slabs + idx;
169
170 kmem_cache_free(bvs->slab, bv);
171 }
172 }
173
174 struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
175 mempool_t *pool)
176 {
177 struct bio_vec *bvl;
178
179 /*
180 * see comment near bvec_array define!
181 */
182 switch (nr) {
183 case 1:
184 *idx = 0;
185 break;
186 case 2 ... 4:
187 *idx = 1;
188 break;
189 case 5 ... 16:
190 *idx = 2;
191 break;
192 case 17 ... 64:
193 *idx = 3;
194 break;
195 case 65 ... 128:
196 *idx = 4;
197 break;
198 case 129 ... BIO_MAX_PAGES:
199 *idx = 5;
200 break;
201 default:
202 return NULL;
203 }
204
205 /*
206 * idx now points to the pool we want to allocate from. only the
207 * 1-vec entry pool is mempool backed.
208 */
209 if (*idx == BIOVEC_MAX_IDX) {
210 fallback:
211 bvl = mempool_alloc(pool, gfp_mask);
212 } else {
213 struct biovec_slab *bvs = bvec_slabs + *idx;
214 gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
215
216 /*
217 * Make this allocation restricted and don't dump info on
218 * allocation failures, since we'll fallback to the mempool
219 * in case of failure.
220 */
221 __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
222
223 /*
224 * Try a slab allocation. If this fails and __GFP_WAIT
225 * is set, retry with the 1-entry mempool
226 */
227 bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
228 if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
229 *idx = BIOVEC_MAX_IDX;
230 goto fallback;
231 }
232 }
233
234 return bvl;
235 }
236
237 static void __bio_free(struct bio *bio)
238 {
239 bio_disassociate_task(bio);
240
241 if (bio_integrity(bio))
242 bio_integrity_free(bio);
243 }
244
245 static void bio_free(struct bio *bio)
246 {
247 struct bio_set *bs = bio->bi_pool;
248 void *p;
249
250 __bio_free(bio);
251
252 if (bs) {
253 if (bio_flagged(bio, BIO_OWNS_VEC))
254 bvec_free(bs->bvec_pool, bio->bi_io_vec, BIO_POOL_IDX(bio));
255
256 /*
257 * If we have front padding, adjust the bio pointer before freeing
258 */
259 p = bio;
260 p -= bs->front_pad;
261
262 mempool_free(p, bs->bio_pool);
263 } else {
264 /* Bio was allocated by bio_kmalloc() */
265 kfree(bio);
266 }
267 }
268
269 void bio_init(struct bio *bio)
270 {
271 memset(bio, 0, sizeof(*bio));
272 bio->bi_flags = 1 << BIO_UPTODATE;
273 atomic_set(&bio->bi_remaining, 1);
274 atomic_set(&bio->bi_cnt, 1);
275 }
276 EXPORT_SYMBOL(bio_init);
277
278 /**
279 * bio_reset - reinitialize a bio
280 * @bio: bio to reset
281 *
282 * Description:
283 * After calling bio_reset(), @bio will be in the same state as a freshly
284 * allocated bio returned bio bio_alloc_bioset() - the only fields that are
285 * preserved are the ones that are initialized by bio_alloc_bioset(). See
286 * comment in struct bio.
287 */
288 void bio_reset(struct bio *bio)
289 {
290 unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
291
292 __bio_free(bio);
293
294 memset(bio, 0, BIO_RESET_BYTES);
295 bio->bi_flags = flags|(1 << BIO_UPTODATE);
296 atomic_set(&bio->bi_remaining, 1);
297 }
298 EXPORT_SYMBOL(bio_reset);
299
300 static void bio_chain_endio(struct bio *bio, int error)
301 {
302 bio_endio(bio->bi_private, error);
303 bio_put(bio);
304 }
305
306 /**
307 * bio_chain - chain bio completions
308 *
309 * The caller won't have a bi_end_io called when @bio completes - instead,
310 * @parent's bi_end_io won't be called until both @parent and @bio have
311 * completed; the chained bio will also be freed when it completes.
312 *
313 * The caller must not set bi_private or bi_end_io in @bio.
314 */
315 void bio_chain(struct bio *bio, struct bio *parent)
316 {
317 BUG_ON(bio->bi_private || bio->bi_end_io);
318
319 bio->bi_private = parent;
320 bio->bi_end_io = bio_chain_endio;
321 atomic_inc(&parent->bi_remaining);
322 }
323 EXPORT_SYMBOL(bio_chain);
324
325 static void bio_alloc_rescue(struct work_struct *work)
326 {
327 struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
328 struct bio *bio;
329
330 while (1) {
331 spin_lock(&bs->rescue_lock);
332 bio = bio_list_pop(&bs->rescue_list);
333 spin_unlock(&bs->rescue_lock);
334
335 if (!bio)
336 break;
337
338 generic_make_request(bio);
339 }
340 }
341
342 static void punt_bios_to_rescuer(struct bio_set *bs)
343 {
344 struct bio_list punt, nopunt;
345 struct bio *bio;
346
347 /*
348 * In order to guarantee forward progress we must punt only bios that
349 * were allocated from this bio_set; otherwise, if there was a bio on
350 * there for a stacking driver higher up in the stack, processing it
351 * could require allocating bios from this bio_set, and doing that from
352 * our own rescuer would be bad.
353 *
354 * Since bio lists are singly linked, pop them all instead of trying to
355 * remove from the middle of the list:
356 */
357
358 bio_list_init(&punt);
359 bio_list_init(&nopunt);
360
361 while ((bio = bio_list_pop(current->bio_list)))
362 bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
363
364 *current->bio_list = nopunt;
365
366 spin_lock(&bs->rescue_lock);
367 bio_list_merge(&bs->rescue_list, &punt);
368 spin_unlock(&bs->rescue_lock);
369
370 queue_work(bs->rescue_workqueue, &bs->rescue_work);
371 }
372
373 /**
374 * bio_alloc_bioset - allocate a bio for I/O
375 * @gfp_mask: the GFP_ mask given to the slab allocator
376 * @nr_iovecs: number of iovecs to pre-allocate
377 * @bs: the bio_set to allocate from.
378 *
379 * Description:
380 * If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
381 * backed by the @bs's mempool.
382 *
383 * When @bs is not NULL, if %__GFP_WAIT is set then bio_alloc will always be
384 * able to allocate a bio. This is due to the mempool guarantees. To make this
385 * work, callers must never allocate more than 1 bio at a time from this pool.
386 * Callers that need to allocate more than 1 bio must always submit the
387 * previously allocated bio for IO before attempting to allocate a new one.
388 * Failure to do so can cause deadlocks under memory pressure.
389 *
390 * Note that when running under generic_make_request() (i.e. any block
391 * driver), bios are not submitted until after you return - see the code in
392 * generic_make_request() that converts recursion into iteration, to prevent
393 * stack overflows.
394 *
395 * This would normally mean allocating multiple bios under
396 * generic_make_request() would be susceptible to deadlocks, but we have
397 * deadlock avoidance code that resubmits any blocked bios from a rescuer
398 * thread.
399 *
400 * However, we do not guarantee forward progress for allocations from other
401 * mempools. Doing multiple allocations from the same mempool under
402 * generic_make_request() should be avoided - instead, use bio_set's front_pad
403 * for per bio allocations.
404 *
405 * RETURNS:
406 * Pointer to new bio on success, NULL on failure.
407 */
408 struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
409 {
410 gfp_t saved_gfp = gfp_mask;
411 unsigned front_pad;
412 unsigned inline_vecs;
413 unsigned long idx = BIO_POOL_NONE;
414 struct bio_vec *bvl = NULL;
415 struct bio *bio;
416 void *p;
417
418 if (!bs) {
419 if (nr_iovecs > UIO_MAXIOV)
420 return NULL;
421
422 p = kmalloc(sizeof(struct bio) +
423 nr_iovecs * sizeof(struct bio_vec),
424 gfp_mask);
425 front_pad = 0;
426 inline_vecs = nr_iovecs;
427 } else {
428 /*
429 * generic_make_request() converts recursion to iteration; this
430 * means if we're running beneath it, any bios we allocate and
431 * submit will not be submitted (and thus freed) until after we
432 * return.
433 *
434 * This exposes us to a potential deadlock if we allocate
435 * multiple bios from the same bio_set() while running
436 * underneath generic_make_request(). If we were to allocate
437 * multiple bios (say a stacking block driver that was splitting
438 * bios), we would deadlock if we exhausted the mempool's
439 * reserve.
440 *
441 * We solve this, and guarantee forward progress, with a rescuer
442 * workqueue per bio_set. If we go to allocate and there are
443 * bios on current->bio_list, we first try the allocation
444 * without __GFP_WAIT; if that fails, we punt those bios we
445 * would be blocking to the rescuer workqueue before we retry
446 * with the original gfp_flags.
447 */
448
449 if (current->bio_list && !bio_list_empty(current->bio_list))
450 gfp_mask &= ~__GFP_WAIT;
451
452 p = mempool_alloc(bs->bio_pool, gfp_mask);
453 if (!p && gfp_mask != saved_gfp) {
454 punt_bios_to_rescuer(bs);
455 gfp_mask = saved_gfp;
456 p = mempool_alloc(bs->bio_pool, gfp_mask);
457 }
458
459 front_pad = bs->front_pad;
460 inline_vecs = BIO_INLINE_VECS;
461 }
462
463 if (unlikely(!p))
464 return NULL;
465
466 bio = p + front_pad;
467 bio_init(bio);
468
469 if (nr_iovecs > inline_vecs) {
470 bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
471 if (!bvl && gfp_mask != saved_gfp) {
472 punt_bios_to_rescuer(bs);
473 gfp_mask = saved_gfp;
474 bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
475 }
476
477 if (unlikely(!bvl))
478 goto err_free;
479
480 bio->bi_flags |= 1 << BIO_OWNS_VEC;
481 } else if (nr_iovecs) {
482 bvl = bio->bi_inline_vecs;
483 }
484
485 bio->bi_pool = bs;
486 bio->bi_flags |= idx << BIO_POOL_OFFSET;
487 bio->bi_max_vecs = nr_iovecs;
488 bio->bi_io_vec = bvl;
489 return bio;
490
491 err_free:
492 mempool_free(p, bs->bio_pool);
493 return NULL;
494 }
495 EXPORT_SYMBOL(bio_alloc_bioset);
496
497 void zero_fill_bio(struct bio *bio)
498 {
499 unsigned long flags;
500 struct bio_vec bv;
501 struct bvec_iter iter;
502
503 bio_for_each_segment(bv, bio, iter) {
504 char *data = bvec_kmap_irq(&bv, &flags);
505 memset(data, 0, bv.bv_len);
506 flush_dcache_page(bv.bv_page);
507 bvec_kunmap_irq(data, &flags);
508 }
509 }
510 EXPORT_SYMBOL(zero_fill_bio);
511
512 /**
513 * bio_put - release a reference to a bio
514 * @bio: bio to release reference to
515 *
516 * Description:
517 * Put a reference to a &struct bio, either one you have gotten with
518 * bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
519 **/
520 void bio_put(struct bio *bio)
521 {
522 BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
523
524 /*
525 * last put frees it
526 */
527 if (atomic_dec_and_test(&bio->bi_cnt))
528 bio_free(bio);
529 }
530 EXPORT_SYMBOL(bio_put);
531
532 inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
533 {
534 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
535 blk_recount_segments(q, bio);
536
537 return bio->bi_phys_segments;
538 }
539 EXPORT_SYMBOL(bio_phys_segments);
540
541 /**
542 * __bio_clone_fast - clone a bio that shares the original bio's biovec
543 * @bio: destination bio
544 * @bio_src: bio to clone
545 *
546 * Clone a &bio. Caller will own the returned bio, but not
547 * the actual data it points to. Reference count of returned
548 * bio will be one.
549 *
550 * Caller must ensure that @bio_src is not freed before @bio.
551 */
552 void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
553 {
554 BUG_ON(bio->bi_pool && BIO_POOL_IDX(bio) != BIO_POOL_NONE);
555
556 /*
557 * most users will be overriding ->bi_bdev with a new target,
558 * so we don't set nor calculate new physical/hw segment counts here
559 */
560 bio->bi_bdev = bio_src->bi_bdev;
561 bio->bi_flags |= 1 << BIO_CLONED;
562 bio->bi_rw = bio_src->bi_rw;
563 bio->bi_iter = bio_src->bi_iter;
564 bio->bi_io_vec = bio_src->bi_io_vec;
565 }
566 EXPORT_SYMBOL(__bio_clone_fast);
567
568 /**
569 * bio_clone_fast - clone a bio that shares the original bio's biovec
570 * @bio: bio to clone
571 * @gfp_mask: allocation priority
572 * @bs: bio_set to allocate from
573 *
574 * Like __bio_clone_fast, only also allocates the returned bio
575 */
576 struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
577 {
578 struct bio *b;
579
580 b = bio_alloc_bioset(gfp_mask, 0, bs);
581 if (!b)
582 return NULL;
583
584 __bio_clone_fast(b, bio);
585
586 if (bio_integrity(bio)) {
587 int ret;
588
589 ret = bio_integrity_clone(b, bio, gfp_mask);
590
591 if (ret < 0) {
592 bio_put(b);
593 return NULL;
594 }
595 }
596
597 return b;
598 }
599 EXPORT_SYMBOL(bio_clone_fast);
600
601 /**
602 * bio_clone_bioset - clone a bio
603 * @bio_src: bio to clone
604 * @gfp_mask: allocation priority
605 * @bs: bio_set to allocate from
606 *
607 * Clone bio. Caller will own the returned bio, but not the actual data it
608 * points to. Reference count of returned bio will be one.
609 */
610 struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
611 struct bio_set *bs)
612 {
613 struct bvec_iter iter;
614 struct bio_vec bv;
615 struct bio *bio;
616
617 /*
618 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
619 * bio_src->bi_io_vec to bio->bi_io_vec.
620 *
621 * We can't do that anymore, because:
622 *
623 * - The point of cloning the biovec is to produce a bio with a biovec
624 * the caller can modify: bi_idx and bi_bvec_done should be 0.
625 *
626 * - The original bio could've had more than BIO_MAX_PAGES biovecs; if
627 * we tried to clone the whole thing bio_alloc_bioset() would fail.
628 * But the clone should succeed as long as the number of biovecs we
629 * actually need to allocate is fewer than BIO_MAX_PAGES.
630 *
631 * - Lastly, bi_vcnt should not be looked at or relied upon by code
632 * that does not own the bio - reason being drivers don't use it for
633 * iterating over the biovec anymore, so expecting it to be kept up
634 * to date (i.e. for clones that share the parent biovec) is just
635 * asking for trouble and would force extra work on
636 * __bio_clone_fast() anyways.
637 */
638
639 bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
640 if (!bio)
641 return NULL;
642
643 bio->bi_bdev = bio_src->bi_bdev;
644 bio->bi_rw = bio_src->bi_rw;
645 bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
646 bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
647
648 if (bio->bi_rw & REQ_DISCARD)
649 goto integrity_clone;
650
651 if (bio->bi_rw & REQ_WRITE_SAME) {
652 bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
653 goto integrity_clone;
654 }
655
656 bio_for_each_segment(bv, bio_src, iter)
657 bio->bi_io_vec[bio->bi_vcnt++] = bv;
658
659 integrity_clone:
660 if (bio_integrity(bio_src)) {
661 int ret;
662
663 ret = bio_integrity_clone(bio, bio_src, gfp_mask);
664 if (ret < 0) {
665 bio_put(bio);
666 return NULL;
667 }
668 }
669
670 return bio;
671 }
672 EXPORT_SYMBOL(bio_clone_bioset);
673
674 /**
675 * bio_get_nr_vecs - return approx number of vecs
676 * @bdev: I/O target
677 *
678 * Return the approximate number of pages we can send to this target.
679 * There's no guarantee that you will be able to fit this number of pages
680 * into a bio, it does not account for dynamic restrictions that vary
681 * on offset.
682 */
683 int bio_get_nr_vecs(struct block_device *bdev)
684 {
685 struct request_queue *q = bdev_get_queue(bdev);
686 int nr_pages;
687
688 nr_pages = min_t(unsigned,
689 queue_max_segments(q),
690 queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
691
692 return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
693
694 }
695 EXPORT_SYMBOL(bio_get_nr_vecs);
696
697 static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
698 *page, unsigned int len, unsigned int offset,
699 unsigned int max_sectors)
700 {
701 int retried_segments = 0;
702 struct bio_vec *bvec;
703
704 /*
705 * cloned bio must not modify vec list
706 */
707 if (unlikely(bio_flagged(bio, BIO_CLONED)))
708 return 0;
709
710 if (((bio->bi_iter.bi_size + len) >> 9) > max_sectors)
711 return 0;
712
713 /*
714 * For filesystems with a blocksize smaller than the pagesize
715 * we will often be called with the same page as last time and
716 * a consecutive offset. Optimize this special case.
717 */
718 if (bio->bi_vcnt > 0) {
719 struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
720
721 if (page == prev->bv_page &&
722 offset == prev->bv_offset + prev->bv_len) {
723 unsigned int prev_bv_len = prev->bv_len;
724 prev->bv_len += len;
725
726 if (q->merge_bvec_fn) {
727 struct bvec_merge_data bvm = {
728 /* prev_bvec is already charged in
729 bi_size, discharge it in order to
730 simulate merging updated prev_bvec
731 as new bvec. */
732 .bi_bdev = bio->bi_bdev,
733 .bi_sector = bio->bi_iter.bi_sector,
734 .bi_size = bio->bi_iter.bi_size -
735 prev_bv_len,
736 .bi_rw = bio->bi_rw,
737 };
738
739 if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
740 prev->bv_len -= len;
741 return 0;
742 }
743 }
744
745 goto done;
746 }
747 }
748
749 if (bio->bi_vcnt >= bio->bi_max_vecs)
750 return 0;
751
752 /*
753 * we might lose a segment or two here, but rather that than
754 * make this too complex.
755 */
756
757 while (bio->bi_phys_segments >= queue_max_segments(q)) {
758
759 if (retried_segments)
760 return 0;
761
762 retried_segments = 1;
763 blk_recount_segments(q, bio);
764 }
765
766 /*
767 * setup the new entry, we might clear it again later if we
768 * cannot add the page
769 */
770 bvec = &bio->bi_io_vec[bio->bi_vcnt];
771 bvec->bv_page = page;
772 bvec->bv_len = len;
773 bvec->bv_offset = offset;
774
775 /*
776 * if queue has other restrictions (eg varying max sector size
777 * depending on offset), it can specify a merge_bvec_fn in the
778 * queue to get further control
779 */
780 if (q->merge_bvec_fn) {
781 struct bvec_merge_data bvm = {
782 .bi_bdev = bio->bi_bdev,
783 .bi_sector = bio->bi_iter.bi_sector,
784 .bi_size = bio->bi_iter.bi_size,
785 .bi_rw = bio->bi_rw,
786 };
787
788 /*
789 * merge_bvec_fn() returns number of bytes it can accept
790 * at this offset
791 */
792 if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
793 bvec->bv_page = NULL;
794 bvec->bv_len = 0;
795 bvec->bv_offset = 0;
796 return 0;
797 }
798 }
799
800 /* If we may be able to merge these biovecs, force a recount */
801 if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
802 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
803
804 bio->bi_vcnt++;
805 bio->bi_phys_segments++;
806 done:
807 bio->bi_iter.bi_size += len;
808 return len;
809 }
810
811 /**
812 * bio_add_pc_page - attempt to add page to bio
813 * @q: the target queue
814 * @bio: destination bio
815 * @page: page to add
816 * @len: vec entry length
817 * @offset: vec entry offset
818 *
819 * Attempt to add a page to the bio_vec maplist. This can fail for a
820 * number of reasons, such as the bio being full or target block device
821 * limitations. The target block device must allow bio's up to PAGE_SIZE,
822 * so it is always possible to add a single page to an empty bio.
823 *
824 * This should only be used by REQ_PC bios.
825 */
826 int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
827 unsigned int len, unsigned int offset)
828 {
829 return __bio_add_page(q, bio, page, len, offset,
830 queue_max_hw_sectors(q));
831 }
832 EXPORT_SYMBOL(bio_add_pc_page);
833
834 /**
835 * bio_add_page - attempt to add page to bio
836 * @bio: destination bio
837 * @page: page to add
838 * @len: vec entry length
839 * @offset: vec entry offset
840 *
841 * Attempt to add a page to the bio_vec maplist. This can fail for a
842 * number of reasons, such as the bio being full or target block device
843 * limitations. The target block device must allow bio's up to PAGE_SIZE,
844 * so it is always possible to add a single page to an empty bio.
845 */
846 int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
847 unsigned int offset)
848 {
849 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
850 return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
851 }
852 EXPORT_SYMBOL(bio_add_page);
853
854 struct submit_bio_ret {
855 struct completion event;
856 int error;
857 };
858
859 static void submit_bio_wait_endio(struct bio *bio, int error)
860 {
861 struct submit_bio_ret *ret = bio->bi_private;
862
863 ret->error = error;
864 complete(&ret->event);
865 }
866
867 /**
868 * submit_bio_wait - submit a bio, and wait until it completes
869 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
870 * @bio: The &struct bio which describes the I/O
871 *
872 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from
873 * bio_endio() on failure.
874 */
875 int submit_bio_wait(int rw, struct bio *bio)
876 {
877 struct submit_bio_ret ret;
878
879 rw |= REQ_SYNC;
880 init_completion(&ret.event);
881 bio->bi_private = &ret;
882 bio->bi_end_io = submit_bio_wait_endio;
883 submit_bio(rw, bio);
884 wait_for_completion(&ret.event);
885
886 return ret.error;
887 }
888 EXPORT_SYMBOL(submit_bio_wait);
889
890 /**
891 * bio_advance - increment/complete a bio by some number of bytes
892 * @bio: bio to advance
893 * @bytes: number of bytes to complete
894 *
895 * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
896 * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
897 * be updated on the last bvec as well.
898 *
899 * @bio will then represent the remaining, uncompleted portion of the io.
900 */
901 void bio_advance(struct bio *bio, unsigned bytes)
902 {
903 if (bio_integrity(bio))
904 bio_integrity_advance(bio, bytes);
905
906 bio_advance_iter(bio, &bio->bi_iter, bytes);
907 }
908 EXPORT_SYMBOL(bio_advance);
909
910 /**
911 * bio_alloc_pages - allocates a single page for each bvec in a bio
912 * @bio: bio to allocate pages for
913 * @gfp_mask: flags for allocation
914 *
915 * Allocates pages up to @bio->bi_vcnt.
916 *
917 * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
918 * freed.
919 */
920 int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
921 {
922 int i;
923 struct bio_vec *bv;
924
925 bio_for_each_segment_all(bv, bio, i) {
926 bv->bv_page = alloc_page(gfp_mask);
927 if (!bv->bv_page) {
928 while (--bv >= bio->bi_io_vec)
929 __free_page(bv->bv_page);
930 return -ENOMEM;
931 }
932 }
933
934 return 0;
935 }
936 EXPORT_SYMBOL(bio_alloc_pages);
937
938 /**
939 * bio_copy_data - copy contents of data buffers from one chain of bios to
940 * another
941 * @src: source bio list
942 * @dst: destination bio list
943 *
944 * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats
945 * @src and @dst as linked lists of bios.
946 *
947 * Stops when it reaches the end of either @src or @dst - that is, copies
948 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
949 */
950 void bio_copy_data(struct bio *dst, struct bio *src)
951 {
952 struct bvec_iter src_iter, dst_iter;
953 struct bio_vec src_bv, dst_bv;
954 void *src_p, *dst_p;
955 unsigned bytes;
956
957 src_iter = src->bi_iter;
958 dst_iter = dst->bi_iter;
959
960 while (1) {
961 if (!src_iter.bi_size) {
962 src = src->bi_next;
963 if (!src)
964 break;
965
966 src_iter = src->bi_iter;
967 }
968
969 if (!dst_iter.bi_size) {
970 dst = dst->bi_next;
971 if (!dst)
972 break;
973
974 dst_iter = dst->bi_iter;
975 }
976
977 src_bv = bio_iter_iovec(src, src_iter);
978 dst_bv = bio_iter_iovec(dst, dst_iter);
979
980 bytes = min(src_bv.bv_len, dst_bv.bv_len);
981
982 src_p = kmap_atomic(src_bv.bv_page);
983 dst_p = kmap_atomic(dst_bv.bv_page);
984
985 memcpy(dst_p + dst_bv.bv_offset,
986 src_p + src_bv.bv_offset,
987 bytes);
988
989 kunmap_atomic(dst_p);
990 kunmap_atomic(src_p);
991
992 bio_advance_iter(src, &src_iter, bytes);
993 bio_advance_iter(dst, &dst_iter, bytes);
994 }
995 }
996 EXPORT_SYMBOL(bio_copy_data);
997
998 struct bio_map_data {
999 int nr_sgvecs;
1000 int is_our_pages;
1001 struct sg_iovec sgvecs[];
1002 };
1003
1004 static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
1005 const struct sg_iovec *iov, int iov_count,
1006 int is_our_pages)
1007 {
1008 memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
1009 bmd->nr_sgvecs = iov_count;
1010 bmd->is_our_pages = is_our_pages;
1011 bio->bi_private = bmd;
1012 }
1013
1014 static struct bio_map_data *bio_alloc_map_data(int nr_segs,
1015 unsigned int iov_count,
1016 gfp_t gfp_mask)
1017 {
1018 if (iov_count > UIO_MAXIOV)
1019 return NULL;
1020
1021 return kmalloc(sizeof(struct bio_map_data) +
1022 sizeof(struct sg_iovec) * iov_count, gfp_mask);
1023 }
1024
1025 static int __bio_copy_iov(struct bio *bio, const struct sg_iovec *iov, int iov_count,
1026 int to_user, int from_user, int do_free_page)
1027 {
1028 int ret = 0, i;
1029 struct bio_vec *bvec;
1030 int iov_idx = 0;
1031 unsigned int iov_off = 0;
1032
1033 bio_for_each_segment_all(bvec, bio, i) {
1034 char *bv_addr = page_address(bvec->bv_page);
1035 unsigned int bv_len = bvec->bv_len;
1036
1037 while (bv_len && iov_idx < iov_count) {
1038 unsigned int bytes;
1039 char __user *iov_addr;
1040
1041 bytes = min_t(unsigned int,
1042 iov[iov_idx].iov_len - iov_off, bv_len);
1043 iov_addr = iov[iov_idx].iov_base + iov_off;
1044
1045 if (!ret) {
1046 if (to_user)
1047 ret = copy_to_user(iov_addr, bv_addr,
1048 bytes);
1049
1050 if (from_user)
1051 ret = copy_from_user(bv_addr, iov_addr,
1052 bytes);
1053
1054 if (ret)
1055 ret = -EFAULT;
1056 }
1057
1058 bv_len -= bytes;
1059 bv_addr += bytes;
1060 iov_addr += bytes;
1061 iov_off += bytes;
1062
1063 if (iov[iov_idx].iov_len == iov_off) {
1064 iov_idx++;
1065 iov_off = 0;
1066 }
1067 }
1068
1069 if (do_free_page)
1070 __free_page(bvec->bv_page);
1071 }
1072
1073 return ret;
1074 }
1075
1076 /**
1077 * bio_uncopy_user - finish previously mapped bio
1078 * @bio: bio being terminated
1079 *
1080 * Free pages allocated from bio_copy_user() and write back data
1081 * to user space in case of a read.
1082 */
1083 int bio_uncopy_user(struct bio *bio)
1084 {
1085 struct bio_map_data *bmd = bio->bi_private;
1086 struct bio_vec *bvec;
1087 int ret = 0, i;
1088
1089 if (!bio_flagged(bio, BIO_NULL_MAPPED)) {
1090 /*
1091 * if we're in a workqueue, the request is orphaned, so
1092 * don't copy into a random user address space, just free.
1093 */
1094 if (current->mm)
1095 ret = __bio_copy_iov(bio, bmd->sgvecs, bmd->nr_sgvecs,
1096 bio_data_dir(bio) == READ,
1097 0, bmd->is_our_pages);
1098 else if (bmd->is_our_pages)
1099 bio_for_each_segment_all(bvec, bio, i)
1100 __free_page(bvec->bv_page);
1101 }
1102 kfree(bmd);
1103 bio_put(bio);
1104 return ret;
1105 }
1106 EXPORT_SYMBOL(bio_uncopy_user);
1107
1108 /**
1109 * bio_copy_user_iov - copy user data to bio
1110 * @q: destination block queue
1111 * @map_data: pointer to the rq_map_data holding pages (if necessary)
1112 * @iov: the iovec.
1113 * @iov_count: number of elements in the iovec
1114 * @write_to_vm: bool indicating writing to pages or not
1115 * @gfp_mask: memory allocation flags
1116 *
1117 * Prepares and returns a bio for indirect user io, bouncing data
1118 * to/from kernel pages as necessary. Must be paired with
1119 * call bio_uncopy_user() on io completion.
1120 */
1121 struct bio *bio_copy_user_iov(struct request_queue *q,
1122 struct rq_map_data *map_data,
1123 const struct sg_iovec *iov, int iov_count,
1124 int write_to_vm, gfp_t gfp_mask)
1125 {
1126 struct bio_map_data *bmd;
1127 struct bio_vec *bvec;
1128 struct page *page;
1129 struct bio *bio;
1130 int i, ret;
1131 int nr_pages = 0;
1132 unsigned int len = 0;
1133 unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
1134
1135 for (i = 0; i < iov_count; i++) {
1136 unsigned long uaddr;
1137 unsigned long end;
1138 unsigned long start;
1139
1140 uaddr = (unsigned long)iov[i].iov_base;
1141 end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1142 start = uaddr >> PAGE_SHIFT;
1143
1144 /*
1145 * Overflow, abort
1146 */
1147 if (end < start)
1148 return ERR_PTR(-EINVAL);
1149
1150 nr_pages += end - start;
1151 len += iov[i].iov_len;
1152 }
1153
1154 if (offset)
1155 nr_pages++;
1156
1157 bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
1158 if (!bmd)
1159 return ERR_PTR(-ENOMEM);
1160
1161 ret = -ENOMEM;
1162 bio = bio_kmalloc(gfp_mask, nr_pages);
1163 if (!bio)
1164 goto out_bmd;
1165
1166 if (!write_to_vm)
1167 bio->bi_rw |= REQ_WRITE;
1168
1169 ret = 0;
1170
1171 if (map_data) {
1172 nr_pages = 1 << map_data->page_order;
1173 i = map_data->offset / PAGE_SIZE;
1174 }
1175 while (len) {
1176 unsigned int bytes = PAGE_SIZE;
1177
1178 bytes -= offset;
1179
1180 if (bytes > len)
1181 bytes = len;
1182
1183 if (map_data) {
1184 if (i == map_data->nr_entries * nr_pages) {
1185 ret = -ENOMEM;
1186 break;
1187 }
1188
1189 page = map_data->pages[i / nr_pages];
1190 page += (i % nr_pages);
1191
1192 i++;
1193 } else {
1194 page = alloc_page(q->bounce_gfp | gfp_mask);
1195 if (!page) {
1196 ret = -ENOMEM;
1197 break;
1198 }
1199 }
1200
1201 if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
1202 break;
1203
1204 len -= bytes;
1205 offset = 0;
1206 }
1207
1208 if (ret)
1209 goto cleanup;
1210
1211 /*
1212 * success
1213 */
1214 if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
1215 (map_data && map_data->from_user)) {
1216 ret = __bio_copy_iov(bio, iov, iov_count, 0, 1, 0);
1217 if (ret)
1218 goto cleanup;
1219 }
1220
1221 bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
1222 return bio;
1223 cleanup:
1224 if (!map_data)
1225 bio_for_each_segment_all(bvec, bio, i)
1226 __free_page(bvec->bv_page);
1227
1228 bio_put(bio);
1229 out_bmd:
1230 kfree(bmd);
1231 return ERR_PTR(ret);
1232 }
1233
1234 /**
1235 * bio_copy_user - copy user data to bio
1236 * @q: destination block queue
1237 * @map_data: pointer to the rq_map_data holding pages (if necessary)
1238 * @uaddr: start of user address
1239 * @len: length in bytes
1240 * @write_to_vm: bool indicating writing to pages or not
1241 * @gfp_mask: memory allocation flags
1242 *
1243 * Prepares and returns a bio for indirect user io, bouncing data
1244 * to/from kernel pages as necessary. Must be paired with
1245 * call bio_uncopy_user() on io completion.
1246 */
1247 struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
1248 unsigned long uaddr, unsigned int len,
1249 int write_to_vm, gfp_t gfp_mask)
1250 {
1251 struct sg_iovec iov;
1252
1253 iov.iov_base = (void __user *)uaddr;
1254 iov.iov_len = len;
1255
1256 return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
1257 }
1258 EXPORT_SYMBOL(bio_copy_user);
1259
1260 static struct bio *__bio_map_user_iov(struct request_queue *q,
1261 struct block_device *bdev,
1262 const struct sg_iovec *iov, int iov_count,
1263 int write_to_vm, gfp_t gfp_mask)
1264 {
1265 int i, j;
1266 int nr_pages = 0;
1267 struct page **pages;
1268 struct bio *bio;
1269 int cur_page = 0;
1270 int ret, offset;
1271
1272 for (i = 0; i < iov_count; i++) {
1273 unsigned long uaddr = (unsigned long)iov[i].iov_base;
1274 unsigned long len = iov[i].iov_len;
1275 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1276 unsigned long start = uaddr >> PAGE_SHIFT;
1277
1278 /*
1279 * Overflow, abort
1280 */
1281 if (end < start)
1282 return ERR_PTR(-EINVAL);
1283
1284 nr_pages += end - start;
1285 /*
1286 * buffer must be aligned to at least hardsector size for now
1287 */
1288 if (uaddr & queue_dma_alignment(q))
1289 return ERR_PTR(-EINVAL);
1290 }
1291
1292 if (!nr_pages)
1293 return ERR_PTR(-EINVAL);
1294
1295 bio = bio_kmalloc(gfp_mask, nr_pages);
1296 if (!bio)
1297 return ERR_PTR(-ENOMEM);
1298
1299 ret = -ENOMEM;
1300 pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
1301 if (!pages)
1302 goto out;
1303
1304 for (i = 0; i < iov_count; i++) {
1305 unsigned long uaddr = (unsigned long)iov[i].iov_base;
1306 unsigned long len = iov[i].iov_len;
1307 unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1308 unsigned long start = uaddr >> PAGE_SHIFT;
1309 const int local_nr_pages = end - start;
1310 const int page_limit = cur_page + local_nr_pages;
1311
1312 ret = get_user_pages_fast(uaddr, local_nr_pages,
1313 write_to_vm, &pages[cur_page]);
1314 if (ret < local_nr_pages) {
1315 ret = -EFAULT;
1316 goto out_unmap;
1317 }
1318
1319 offset = uaddr & ~PAGE_MASK;
1320 for (j = cur_page; j < page_limit; j++) {
1321 unsigned int bytes = PAGE_SIZE - offset;
1322
1323 if (len <= 0)
1324 break;
1325
1326 if (bytes > len)
1327 bytes = len;
1328
1329 /*
1330 * sorry...
1331 */
1332 if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
1333 bytes)
1334 break;
1335
1336 len -= bytes;
1337 offset = 0;
1338 }
1339
1340 cur_page = j;
1341 /*
1342 * release the pages we didn't map into the bio, if any
1343 */
1344 while (j < page_limit)
1345 page_cache_release(pages[j++]);
1346 }
1347
1348 kfree(pages);
1349
1350 /*
1351 * set data direction, and check if mapped pages need bouncing
1352 */
1353 if (!write_to_vm)
1354 bio->bi_rw |= REQ_WRITE;
1355
1356 bio->bi_bdev = bdev;
1357 bio->bi_flags |= (1 << BIO_USER_MAPPED);
1358 return bio;
1359
1360 out_unmap:
1361 for (i = 0; i < nr_pages; i++) {
1362 if(!pages[i])
1363 break;
1364 page_cache_release(pages[i]);
1365 }
1366 out:
1367 kfree(pages);
1368 bio_put(bio);
1369 return ERR_PTR(ret);
1370 }
1371
1372 /**
1373 * bio_map_user - map user address into bio
1374 * @q: the struct request_queue for the bio
1375 * @bdev: destination block device
1376 * @uaddr: start of user address
1377 * @len: length in bytes
1378 * @write_to_vm: bool indicating writing to pages or not
1379 * @gfp_mask: memory allocation flags
1380 *
1381 * Map the user space address into a bio suitable for io to a block
1382 * device. Returns an error pointer in case of error.
1383 */
1384 struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
1385 unsigned long uaddr, unsigned int len, int write_to_vm,
1386 gfp_t gfp_mask)
1387 {
1388 struct sg_iovec iov;
1389
1390 iov.iov_base = (void __user *)uaddr;
1391 iov.iov_len = len;
1392
1393 return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
1394 }
1395 EXPORT_SYMBOL(bio_map_user);
1396
1397 /**
1398 * bio_map_user_iov - map user sg_iovec table into bio
1399 * @q: the struct request_queue for the bio
1400 * @bdev: destination block device
1401 * @iov: the iovec.
1402 * @iov_count: number of elements in the iovec
1403 * @write_to_vm: bool indicating writing to pages or not
1404 * @gfp_mask: memory allocation flags
1405 *
1406 * Map the user space address into a bio suitable for io to a block
1407 * device. Returns an error pointer in case of error.
1408 */
1409 struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
1410 const struct sg_iovec *iov, int iov_count,
1411 int write_to_vm, gfp_t gfp_mask)
1412 {
1413 struct bio *bio;
1414
1415 bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
1416 gfp_mask);
1417 if (IS_ERR(bio))
1418 return bio;
1419
1420 /*
1421 * subtle -- if __bio_map_user() ended up bouncing a bio,
1422 * it would normally disappear when its bi_end_io is run.
1423 * however, we need it for the unmap, so grab an extra
1424 * reference to it
1425 */
1426 bio_get(bio);
1427
1428 return bio;
1429 }
1430
1431 static void __bio_unmap_user(struct bio *bio)
1432 {
1433 struct bio_vec *bvec;
1434 int i;
1435
1436 /*
1437 * make sure we dirty pages we wrote to
1438 */
1439 bio_for_each_segment_all(bvec, bio, i) {
1440 if (bio_data_dir(bio) == READ)
1441 set_page_dirty_lock(bvec->bv_page);
1442
1443 page_cache_release(bvec->bv_page);
1444 }
1445
1446 bio_put(bio);
1447 }
1448
1449 /**
1450 * bio_unmap_user - unmap a bio
1451 * @bio: the bio being unmapped
1452 *
1453 * Unmap a bio previously mapped by bio_map_user(). Must be called with
1454 * a process context.
1455 *
1456 * bio_unmap_user() may sleep.
1457 */
1458 void bio_unmap_user(struct bio *bio)
1459 {
1460 __bio_unmap_user(bio);
1461 bio_put(bio);
1462 }
1463 EXPORT_SYMBOL(bio_unmap_user);
1464
1465 static void bio_map_kern_endio(struct bio *bio, int err)
1466 {
1467 bio_put(bio);
1468 }
1469
1470 static struct bio *__bio_map_kern(struct request_queue *q, void *data,
1471 unsigned int len, gfp_t gfp_mask)
1472 {
1473 unsigned long kaddr = (unsigned long)data;
1474 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1475 unsigned long start = kaddr >> PAGE_SHIFT;
1476 const int nr_pages = end - start;
1477 int offset, i;
1478 struct bio *bio;
1479
1480 bio = bio_kmalloc(gfp_mask, nr_pages);
1481 if (!bio)
1482 return ERR_PTR(-ENOMEM);
1483
1484 offset = offset_in_page(kaddr);
1485 for (i = 0; i < nr_pages; i++) {
1486 unsigned int bytes = PAGE_SIZE - offset;
1487
1488 if (len <= 0)
1489 break;
1490
1491 if (bytes > len)
1492 bytes = len;
1493
1494 if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1495 offset) < bytes)
1496 break;
1497
1498 data += bytes;
1499 len -= bytes;
1500 offset = 0;
1501 }
1502
1503 bio->bi_end_io = bio_map_kern_endio;
1504 return bio;
1505 }
1506
1507 /**
1508 * bio_map_kern - map kernel address into bio
1509 * @q: the struct request_queue for the bio
1510 * @data: pointer to buffer to map
1511 * @len: length in bytes
1512 * @gfp_mask: allocation flags for bio allocation
1513 *
1514 * Map the kernel address into a bio suitable for io to a block
1515 * device. Returns an error pointer in case of error.
1516 */
1517 struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1518 gfp_t gfp_mask)
1519 {
1520 struct bio *bio;
1521
1522 bio = __bio_map_kern(q, data, len, gfp_mask);
1523 if (IS_ERR(bio))
1524 return bio;
1525
1526 if (bio->bi_iter.bi_size == len)
1527 return bio;
1528
1529 /*
1530 * Don't support partial mappings.
1531 */
1532 bio_put(bio);
1533 return ERR_PTR(-EINVAL);
1534 }
1535 EXPORT_SYMBOL(bio_map_kern);
1536
1537 static void bio_copy_kern_endio(struct bio *bio, int err)
1538 {
1539 struct bio_vec *bvec;
1540 const int read = bio_data_dir(bio) == READ;
1541 struct bio_map_data *bmd = bio->bi_private;
1542 int i;
1543 char *p = bmd->sgvecs[0].iov_base;
1544
1545 bio_for_each_segment_all(bvec, bio, i) {
1546 char *addr = page_address(bvec->bv_page);
1547
1548 if (read)
1549 memcpy(p, addr, bvec->bv_len);
1550
1551 __free_page(bvec->bv_page);
1552 p += bvec->bv_len;
1553 }
1554
1555 kfree(bmd);
1556 bio_put(bio);
1557 }
1558
1559 /**
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
1566 *
1567 * copy the kernel address into a bio suitable for io to a block
1568 * device. Returns an error pointer in case of error.
1569 */
1570 struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1571 gfp_t gfp_mask, int reading)
1572 {
1573 struct bio *bio;
1574 struct bio_vec *bvec;
1575 int i;
1576
1577 bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
1578 if (IS_ERR(bio))
1579 return bio;
1580
1581 if (!reading) {
1582 void *p = data;
1583
1584 bio_for_each_segment_all(bvec, bio, i) {
1585 char *addr = page_address(bvec->bv_page);
1586
1587 memcpy(addr, p, bvec->bv_len);
1588 p += bvec->bv_len;
1589 }
1590 }
1591
1592 bio->bi_end_io = bio_copy_kern_endio;
1593
1594 return bio;
1595 }
1596 EXPORT_SYMBOL(bio_copy_kern);
1597
1598 /*
1599 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1600 * for performing direct-IO in BIOs.
1601 *
1602 * The problem is that we cannot run set_page_dirty() from interrupt context
1603 * because the required locks are not interrupt-safe. So what we can do is to
1604 * mark the pages dirty _before_ performing IO. And in interrupt context,
1605 * check that the pages are still dirty. If so, fine. If not, redirty them
1606 * in process context.
1607 *
1608 * We special-case compound pages here: normally this means reads into hugetlb
1609 * pages. The logic in here doesn't really work right for compound pages
1610 * because the VM does not uniformly chase down the head page in all cases.
1611 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1612 * handle them at all. So we skip compound pages here at an early stage.
1613 *
1614 * Note that this code is very hard to test under normal circumstances because
1615 * direct-io pins the pages with get_user_pages(). This makes
1616 * is_page_cache_freeable return false, and the VM will not clean the pages.
1617 * But other code (eg, flusher threads) could clean the pages if they are mapped
1618 * pagecache.
1619 *
1620 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1621 * deferred bio dirtying paths.
1622 */
1623
1624 /*
1625 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1626 */
1627 void bio_set_pages_dirty(struct bio *bio)
1628 {
1629 struct bio_vec *bvec;
1630 int i;
1631
1632 bio_for_each_segment_all(bvec, bio, i) {
1633 struct page *page = bvec->bv_page;
1634
1635 if (page && !PageCompound(page))
1636 set_page_dirty_lock(page);
1637 }
1638 }
1639
1640 static void bio_release_pages(struct bio *bio)
1641 {
1642 struct bio_vec *bvec;
1643 int i;
1644
1645 bio_for_each_segment_all(bvec, bio, i) {
1646 struct page *page = bvec->bv_page;
1647
1648 if (page)
1649 put_page(page);
1650 }
1651 }
1652
1653 /*
1654 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1655 * If they are, then fine. If, however, some pages are clean then they must
1656 * have been written out during the direct-IO read. So we take another ref on
1657 * the BIO and the offending pages and re-dirty the pages in process context.
1658 *
1659 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1660 * here on. It will run one page_cache_release() against each page and will
1661 * run one bio_put() against the BIO.
1662 */
1663
1664 static void bio_dirty_fn(struct work_struct *work);
1665
1666 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1667 static DEFINE_SPINLOCK(bio_dirty_lock);
1668 static struct bio *bio_dirty_list;
1669
1670 /*
1671 * This runs in process context
1672 */
1673 static void bio_dirty_fn(struct work_struct *work)
1674 {
1675 unsigned long flags;
1676 struct bio *bio;
1677
1678 spin_lock_irqsave(&bio_dirty_lock, flags);
1679 bio = bio_dirty_list;
1680 bio_dirty_list = NULL;
1681 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1682
1683 while (bio) {
1684 struct bio *next = bio->bi_private;
1685
1686 bio_set_pages_dirty(bio);
1687 bio_release_pages(bio);
1688 bio_put(bio);
1689 bio = next;
1690 }
1691 }
1692
1693 void bio_check_pages_dirty(struct bio *bio)
1694 {
1695 struct bio_vec *bvec;
1696 int nr_clean_pages = 0;
1697 int i;
1698
1699 bio_for_each_segment_all(bvec, bio, i) {
1700 struct page *page = bvec->bv_page;
1701
1702 if (PageDirty(page) || PageCompound(page)) {
1703 page_cache_release(page);
1704 bvec->bv_page = NULL;
1705 } else {
1706 nr_clean_pages++;
1707 }
1708 }
1709
1710 if (nr_clean_pages) {
1711 unsigned long flags;
1712
1713 spin_lock_irqsave(&bio_dirty_lock, flags);
1714 bio->bi_private = bio_dirty_list;
1715 bio_dirty_list = bio;
1716 spin_unlock_irqrestore(&bio_dirty_lock, flags);
1717 schedule_work(&bio_dirty_work);
1718 } else {
1719 bio_put(bio);
1720 }
1721 }
1722
1723 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1724 void bio_flush_dcache_pages(struct bio *bi)
1725 {
1726 struct bio_vec bvec;
1727 struct bvec_iter iter;
1728
1729 bio_for_each_segment(bvec, bi, iter)
1730 flush_dcache_page(bvec.bv_page);
1731 }
1732 EXPORT_SYMBOL(bio_flush_dcache_pages);
1733 #endif
1734
1735 /**
1736 * bio_endio - end I/O on a bio
1737 * @bio: bio
1738 * @error: error, if any
1739 *
1740 * Description:
1741 * bio_endio() will end I/O on the whole bio. bio_endio() is the
1742 * preferred way to end I/O on a bio, it takes care of clearing
1743 * BIO_UPTODATE on error. @error is 0 on success, and and one of the
1744 * established -Exxxx (-EIO, for instance) error values in case
1745 * something went wrong. No one should call bi_end_io() directly on a
1746 * bio unless they own it and thus know that it has an end_io
1747 * function.
1748 **/
1749 void bio_endio(struct bio *bio, int error)
1750 {
1751 while (bio) {
1752 BUG_ON(atomic_read(&bio->bi_remaining) <= 0);
1753
1754 if (error)
1755 clear_bit(BIO_UPTODATE, &bio->bi_flags);
1756 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1757 error = -EIO;
1758
1759 if (!atomic_dec_and_test(&bio->bi_remaining))
1760 return;
1761
1762 /*
1763 * Need to have a real endio function for chained bios,
1764 * otherwise various corner cases will break (like stacking
1765 * block devices that save/restore bi_end_io) - however, we want
1766 * to avoid unbounded recursion and blowing the stack. Tail call
1767 * optimization would handle this, but compiling with frame
1768 * pointers also disables gcc's sibling call optimization.
1769 */
1770 if (bio->bi_end_io == bio_chain_endio) {
1771 struct bio *parent = bio->bi_private;
1772 bio_put(bio);
1773 bio = parent;
1774 } else {
1775 if (bio->bi_end_io)
1776 bio->bi_end_io(bio, error);
1777 bio = NULL;
1778 }
1779 }
1780 }
1781 EXPORT_SYMBOL(bio_endio);
1782
1783 /**
1784 * bio_endio_nodec - end I/O on a bio, without decrementing bi_remaining
1785 * @bio: bio
1786 * @error: error, if any
1787 *
1788 * For code that has saved and restored bi_end_io; thing hard before using this
1789 * function, probably you should've cloned the entire bio.
1790 **/
1791 void bio_endio_nodec(struct bio *bio, int error)
1792 {
1793 atomic_inc(&bio->bi_remaining);
1794 bio_endio(bio, error);
1795 }
1796 EXPORT_SYMBOL(bio_endio_nodec);
1797
1798 /**
1799 * bio_split - split a bio
1800 * @bio: bio to split
1801 * @sectors: number of sectors to split from the front of @bio
1802 * @gfp: gfp mask
1803 * @bs: bio set to allocate from
1804 *
1805 * Allocates and returns a new bio which represents @sectors from the start of
1806 * @bio, and updates @bio to represent the remaining sectors.
1807 *
1808 * The newly allocated bio will point to @bio's bi_io_vec; it is the caller's
1809 * responsibility to ensure that @bio is not freed before the split.
1810 */
1811 struct bio *bio_split(struct bio *bio, int sectors,
1812 gfp_t gfp, struct bio_set *bs)
1813 {
1814 struct bio *split = NULL;
1815
1816 BUG_ON(sectors <= 0);
1817 BUG_ON(sectors >= bio_sectors(bio));
1818
1819 split = bio_clone_fast(bio, gfp, bs);
1820 if (!split)
1821 return NULL;
1822
1823 split->bi_iter.bi_size = sectors << 9;
1824
1825 if (bio_integrity(split))
1826 bio_integrity_trim(split, 0, sectors);
1827
1828 bio_advance(bio, split->bi_iter.bi_size);
1829
1830 return split;
1831 }
1832 EXPORT_SYMBOL(bio_split);
1833
1834 /**
1835 * bio_trim - trim a bio
1836 * @bio: bio to trim
1837 * @offset: number of sectors to trim from the front of @bio
1838 * @size: size we want to trim @bio to, in sectors
1839 */
1840 void bio_trim(struct bio *bio, int offset, int size)
1841 {
1842 /* 'bio' is a cloned bio which we need to trim to match
1843 * the given offset and size.
1844 */
1845
1846 size <<= 9;
1847 if (offset == 0 && size == bio->bi_iter.bi_size)
1848 return;
1849
1850 clear_bit(BIO_SEG_VALID, &bio->bi_flags);
1851
1852 bio_advance(bio, offset << 9);
1853
1854 bio->bi_iter.bi_size = size;
1855 }
1856 EXPORT_SYMBOL_GPL(bio_trim);
1857
1858 /*
1859 * create memory pools for biovec's in a bio_set.
1860 * use the global biovec slabs created for general use.
1861 */
1862 mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries)
1863 {
1864 struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
1865
1866 return mempool_create_slab_pool(pool_entries, bp->slab);
1867 }
1868
1869 void bioset_free(struct bio_set *bs)
1870 {
1871 if (bs->rescue_workqueue)
1872 destroy_workqueue(bs->rescue_workqueue);
1873
1874 if (bs->bio_pool)
1875 mempool_destroy(bs->bio_pool);
1876
1877 if (bs->bvec_pool)
1878 mempool_destroy(bs->bvec_pool);
1879
1880 bioset_integrity_free(bs);
1881 bio_put_slab(bs);
1882
1883 kfree(bs);
1884 }
1885 EXPORT_SYMBOL(bioset_free);
1886
1887 /**
1888 * bioset_create - Create a bio_set
1889 * @pool_size: Number of bio and bio_vecs to cache in the mempool
1890 * @front_pad: Number of bytes to allocate in front of the returned bio
1891 *
1892 * Description:
1893 * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1894 * to ask for a number of bytes to be allocated in front of the bio.
1895 * Front pad allocation is useful for embedding the bio inside
1896 * another structure, to avoid allocating extra data to go with the bio.
1897 * Note that the bio must be embedded at the END of that structure always,
1898 * or things will break badly.
1899 */
1900 struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
1901 {
1902 unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1903 struct bio_set *bs;
1904
1905 bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1906 if (!bs)
1907 return NULL;
1908
1909 bs->front_pad = front_pad;
1910
1911 spin_lock_init(&bs->rescue_lock);
1912 bio_list_init(&bs->rescue_list);
1913 INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
1914
1915 bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1916 if (!bs->bio_slab) {
1917 kfree(bs);
1918 return NULL;
1919 }
1920
1921 bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
1922 if (!bs->bio_pool)
1923 goto bad;
1924
1925 bs->bvec_pool = biovec_create_pool(bs, pool_size);
1926 if (!bs->bvec_pool)
1927 goto bad;
1928
1929 bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
1930 if (!bs->rescue_workqueue)
1931 goto bad;
1932
1933 return bs;
1934 bad:
1935 bioset_free(bs);
1936 return NULL;
1937 }
1938 EXPORT_SYMBOL(bioset_create);
1939
1940 #ifdef CONFIG_BLK_CGROUP
1941 /**
1942 * bio_associate_current - associate a bio with %current
1943 * @bio: target bio
1944 *
1945 * Associate @bio with %current if it hasn't been associated yet. Block
1946 * layer will treat @bio as if it were issued by %current no matter which
1947 * task actually issues it.
1948 *
1949 * This function takes an extra reference of @task's io_context and blkcg
1950 * which will be put when @bio is released. The caller must own @bio,
1951 * ensure %current->io_context exists, and is responsible for synchronizing
1952 * calls to this function.
1953 */
1954 int bio_associate_current(struct bio *bio)
1955 {
1956 struct io_context *ioc;
1957 struct cgroup_subsys_state *css;
1958
1959 if (bio->bi_ioc)
1960 return -EBUSY;
1961
1962 ioc = current->io_context;
1963 if (!ioc)
1964 return -ENOENT;
1965
1966 /* acquire active ref on @ioc and associate */
1967 get_io_context_active(ioc);
1968 bio->bi_ioc = ioc;
1969
1970 /* associate blkcg if exists */
1971 rcu_read_lock();
1972 css = task_css(current, blkio_cgrp_id);
1973 if (css && css_tryget(css))
1974 bio->bi_css = css;
1975 rcu_read_unlock();
1976
1977 return 0;
1978 }
1979
1980 /**
1981 * bio_disassociate_task - undo bio_associate_current()
1982 * @bio: target bio
1983 */
1984 void bio_disassociate_task(struct bio *bio)
1985 {
1986 if (bio->bi_ioc) {
1987 put_io_context(bio->bi_ioc);
1988 bio->bi_ioc = NULL;
1989 }
1990 if (bio->bi_css) {
1991 css_put(bio->bi_css);
1992 bio->bi_css = NULL;
1993 }
1994 }
1995
1996 #endif /* CONFIG_BLK_CGROUP */
1997
1998 static void __init biovec_init_slabs(void)
1999 {
2000 int i;
2001
2002 for (i = 0; i < BIOVEC_NR_POOLS; i++) {
2003 int size;
2004 struct biovec_slab *bvs = bvec_slabs + i;
2005
2006 if (bvs->nr_vecs <= BIO_INLINE_VECS) {
2007 bvs->slab = NULL;
2008 continue;
2009 }
2010
2011 size = bvs->nr_vecs * sizeof(struct bio_vec);
2012 bvs->slab = kmem_cache_create(bvs->name, size, 0,
2013 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2014 }
2015 }
2016
2017 static int __init init_bio(void)
2018 {
2019 bio_slab_max = 2;
2020 bio_slab_nr = 0;
2021 bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
2022 if (!bio_slabs)
2023 panic("bio: can't allocate bios\n");
2024
2025 bio_integrity_init();
2026 biovec_init_slabs();
2027
2028 fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
2029 if (!fs_bio_set)
2030 panic("bio: can't allocate bios\n");
2031
2032 if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
2033 panic("bio: can't create integrity pool\n");
2034
2035 return 0;
2036 }
2037 subsys_initcall(init_bio);
2038
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