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TOMOYO Linux Cross Reference
Linux/include/linux/bio.h

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  1 /*
  2  * 2.5 block I/O model
  3  *
  4  * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  *
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  *
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public Licens
 17  * along with this program; if not, write to the Free Software
 18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 19  */
 20 #ifndef __LINUX_BIO_H
 21 #define __LINUX_BIO_H
 22 
 23 #include <linux/highmem.h>
 24 #include <linux/mempool.h>
 25 #include <linux/ioprio.h>
 26 #include <linux/bug.h>
 27 
 28 #ifdef CONFIG_BLOCK
 29 
 30 #include <asm/io.h>
 31 
 32 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
 33 #include <linux/blk_types.h>
 34 
 35 #define BIO_DEBUG
 36 
 37 #ifdef BIO_DEBUG
 38 #define BIO_BUG_ON      BUG_ON
 39 #else
 40 #define BIO_BUG_ON
 41 #endif
 42 
 43 #define BIO_MAX_PAGES           256
 44 #define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
 45 #define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
 46 
 47 /*
 48  * upper 16 bits of bi_rw define the io priority of this bio
 49  */
 50 #define BIO_PRIO_SHIFT  (8 * sizeof(unsigned long) - IOPRIO_BITS)
 51 #define bio_prio(bio)   ((bio)->bi_rw >> BIO_PRIO_SHIFT)
 52 #define bio_prio_valid(bio)     ioprio_valid(bio_prio(bio))
 53 
 54 #define bio_set_prio(bio, prio)         do {                    \
 55         WARN_ON(prio >= (1 << IOPRIO_BITS));                    \
 56         (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);          \
 57         (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);     \
 58 } while (0)
 59 
 60 /*
 61  * various member access, note that bio_data should of course not be used
 62  * on highmem page vectors
 63  */
 64 #define __bvec_iter_bvec(bvec, iter)    (&(bvec)[(iter).bi_idx])
 65 
 66 #define bvec_iter_page(bvec, iter)                              \
 67         (__bvec_iter_bvec((bvec), (iter))->bv_page)
 68 
 69 #define bvec_iter_len(bvec, iter)                               \
 70         min((iter).bi_size,                                     \
 71             __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
 72 
 73 #define bvec_iter_offset(bvec, iter)                            \
 74         (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
 75 
 76 #define bvec_iter_bvec(bvec, iter)                              \
 77 ((struct bio_vec) {                                             \
 78         .bv_page        = bvec_iter_page((bvec), (iter)),       \
 79         .bv_len         = bvec_iter_len((bvec), (iter)),        \
 80         .bv_offset      = bvec_iter_offset((bvec), (iter)),     \
 81 })
 82 
 83 #define bio_iter_iovec(bio, iter)                               \
 84         bvec_iter_bvec((bio)->bi_io_vec, (iter))
 85 
 86 #define bio_iter_page(bio, iter)                                \
 87         bvec_iter_page((bio)->bi_io_vec, (iter))
 88 #define bio_iter_len(bio, iter)                                 \
 89         bvec_iter_len((bio)->bi_io_vec, (iter))
 90 #define bio_iter_offset(bio, iter)                              \
 91         bvec_iter_offset((bio)->bi_io_vec, (iter))
 92 
 93 #define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
 94 #define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
 95 #define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
 96 
 97 #define bio_multiple_segments(bio)                              \
 98         ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
 99 #define bio_sectors(bio)        ((bio)->bi_iter.bi_size >> 9)
100 #define bio_end_sector(bio)     ((bio)->bi_iter.bi_sector + bio_sectors((bio)))
101 
102 /*
103  * Check whether this bio carries any data or not. A NULL bio is allowed.
104  */
105 static inline bool bio_has_data(struct bio *bio)
106 {
107         if (bio &&
108             bio->bi_iter.bi_size &&
109             !(bio->bi_rw & REQ_DISCARD))
110                 return true;
111 
112         return false;
113 }
114 
115 static inline bool bio_is_rw(struct bio *bio)
116 {
117         if (!bio_has_data(bio))
118                 return false;
119 
120         if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
121                 return false;
122 
123         return true;
124 }
125 
126 static inline bool bio_mergeable(struct bio *bio)
127 {
128         if (bio->bi_rw & REQ_NOMERGE_FLAGS)
129                 return false;
130 
131         return true;
132 }
133 
134 static inline unsigned int bio_cur_bytes(struct bio *bio)
135 {
136         if (bio_has_data(bio))
137                 return bio_iovec(bio).bv_len;
138         else /* dataless requests such as discard */
139                 return bio->bi_iter.bi_size;
140 }
141 
142 static inline void *bio_data(struct bio *bio)
143 {
144         if (bio_has_data(bio))
145                 return page_address(bio_page(bio)) + bio_offset(bio);
146 
147         return NULL;
148 }
149 
150 /*
151  * will die
152  */
153 #define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
154 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
155 
156 /*
157  * queues that have highmem support enabled may still need to revert to
158  * PIO transfers occasionally and thus map high pages temporarily. For
159  * permanent PIO fall back, user is probably better off disabling highmem
160  * I/O completely on that queue (see ide-dma for example)
161  */
162 #define __bio_kmap_atomic(bio, iter)                            \
163         (kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) +   \
164                 bio_iter_iovec((bio), (iter)).bv_offset)
165 
166 #define __bio_kunmap_atomic(addr)       kunmap_atomic(addr)
167 
168 /*
169  * merge helpers etc
170  */
171 
172 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
173 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
174         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
175 
176 /*
177  * allow arch override, for eg virtualized architectures (put in asm/io.h)
178  */
179 #ifndef BIOVEC_PHYS_MERGEABLE
180 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
181         __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
182 #endif
183 
184 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
185         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
186 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
187         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
188 
189 /*
190  * Check if adding a bio_vec after bprv with offset would create a gap in
191  * the SG list. Most drivers don't care about this, but some do.
192  */
193 static inline bool bvec_gap_to_prev(struct bio_vec *bprv, unsigned int offset)
194 {
195         return offset || ((bprv->bv_offset + bprv->bv_len) & (PAGE_SIZE - 1));
196 }
197 
198 #define bio_io_error(bio) bio_endio((bio), -EIO)
199 
200 /*
201  * drivers should _never_ use the all version - the bio may have been split
202  * before it got to the driver and the driver won't own all of it
203  */
204 #define bio_for_each_segment_all(bvl, bio, i)                           \
205         for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
206 
207 static inline void bvec_iter_advance(struct bio_vec *bv, struct bvec_iter *iter,
208                                      unsigned bytes)
209 {
210         WARN_ONCE(bytes > iter->bi_size,
211                   "Attempted to advance past end of bvec iter\n");
212 
213         while (bytes) {
214                 unsigned len = min(bytes, bvec_iter_len(bv, *iter));
215 
216                 bytes -= len;
217                 iter->bi_size -= len;
218                 iter->bi_bvec_done += len;
219 
220                 if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
221                         iter->bi_bvec_done = 0;
222                         iter->bi_idx++;
223                 }
224         }
225 }
226 
227 #define for_each_bvec(bvl, bio_vec, iter, start)                        \
228         for (iter = (start);                                            \
229              (iter).bi_size &&                                          \
230                 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
231              bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
232 
233 
234 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
235                                     unsigned bytes)
236 {
237         iter->bi_sector += bytes >> 9;
238 
239         if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
240                 iter->bi_size -= bytes;
241         else
242                 bvec_iter_advance(bio->bi_io_vec, iter, bytes);
243 }
244 
245 #define __bio_for_each_segment(bvl, bio, iter, start)                   \
246         for (iter = (start);                                            \
247              (iter).bi_size &&                                          \
248                 ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
249              bio_advance_iter((bio), &(iter), (bvl).bv_len))
250 
251 #define bio_for_each_segment(bvl, bio, iter)                            \
252         __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
253 
254 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
255 
256 static inline unsigned bio_segments(struct bio *bio)
257 {
258         unsigned segs = 0;
259         struct bio_vec bv;
260         struct bvec_iter iter;
261 
262         /*
263          * We special case discard/write same, because they interpret bi_size
264          * differently:
265          */
266 
267         if (bio->bi_rw & REQ_DISCARD)
268                 return 1;
269 
270         if (bio->bi_rw & REQ_WRITE_SAME)
271                 return 1;
272 
273         bio_for_each_segment(bv, bio, iter)
274                 segs++;
275 
276         return segs;
277 }
278 
279 /*
280  * get a reference to a bio, so it won't disappear. the intended use is
281  * something like:
282  *
283  * bio_get(bio);
284  * submit_bio(rw, bio);
285  * if (bio->bi_flags ...)
286  *      do_something
287  * bio_put(bio);
288  *
289  * without the bio_get(), it could potentially complete I/O before submit_bio
290  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
291  * runs
292  */
293 #define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
294 
295 enum bip_flags {
296         BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
297         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
298         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
299         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
300         BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
301 };
302 
303 #if defined(CONFIG_BLK_DEV_INTEGRITY)
304 
305 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
306 {
307         if (bio->bi_rw & REQ_INTEGRITY)
308                 return bio->bi_integrity;
309 
310         return NULL;
311 }
312 
313 /*
314  * bio integrity payload
315  */
316 struct bio_integrity_payload {
317         struct bio              *bip_bio;       /* parent bio */
318 
319         struct bvec_iter        bip_iter;
320 
321         bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
322 
323         unsigned short          bip_slab;       /* slab the bip came from */
324         unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
325         unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
326         unsigned short          bip_flags;      /* control flags */
327 
328         struct work_struct      bip_work;       /* I/O completion */
329 
330         struct bio_vec          *bip_vec;
331         struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
332 };
333 
334 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
335 {
336         struct bio_integrity_payload *bip = bio_integrity(bio);
337 
338         if (bip)
339                 return bip->bip_flags & flag;
340 
341         return false;
342 }
343 
344 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
345 {
346         return bip->bip_iter.bi_sector;
347 }
348 
349 static inline void bip_set_seed(struct bio_integrity_payload *bip,
350                                 sector_t seed)
351 {
352         bip->bip_iter.bi_sector = seed;
353 }
354 
355 #endif /* CONFIG_BLK_DEV_INTEGRITY */
356 
357 extern void bio_trim(struct bio *bio, int offset, int size);
358 extern struct bio *bio_split(struct bio *bio, int sectors,
359                              gfp_t gfp, struct bio_set *bs);
360 
361 /**
362  * bio_next_split - get next @sectors from a bio, splitting if necessary
363  * @bio:        bio to split
364  * @sectors:    number of sectors to split from the front of @bio
365  * @gfp:        gfp mask
366  * @bs:         bio set to allocate from
367  *
368  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
369  * than @sectors, returns the original bio unchanged.
370  */
371 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
372                                          gfp_t gfp, struct bio_set *bs)
373 {
374         if (sectors >= bio_sectors(bio))
375                 return bio;
376 
377         return bio_split(bio, sectors, gfp, bs);
378 }
379 
380 extern struct bio_set *bioset_create(unsigned int, unsigned int);
381 extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
382 extern void bioset_free(struct bio_set *);
383 extern mempool_t *biovec_create_pool(int pool_entries);
384 
385 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
386 extern void bio_put(struct bio *);
387 
388 extern void __bio_clone_fast(struct bio *, struct bio *);
389 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
390 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
391 
392 extern struct bio_set *fs_bio_set;
393 
394 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
395 {
396         return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
397 }
398 
399 static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
400 {
401         return bio_clone_bioset(bio, gfp_mask, fs_bio_set);
402 }
403 
404 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
405 {
406         return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
407 }
408 
409 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
410 {
411         return bio_clone_bioset(bio, gfp_mask, NULL);
412 
413 }
414 
415 extern void bio_endio(struct bio *, int);
416 extern void bio_endio_nodec(struct bio *, int);
417 struct request_queue;
418 extern int bio_phys_segments(struct request_queue *, struct bio *);
419 
420 extern int submit_bio_wait(int rw, struct bio *bio);
421 extern void bio_advance(struct bio *, unsigned);
422 
423 extern void bio_init(struct bio *);
424 extern void bio_reset(struct bio *);
425 void bio_chain(struct bio *, struct bio *);
426 
427 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
428 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
429                            unsigned int, unsigned int);
430 extern int bio_get_nr_vecs(struct block_device *);
431 struct rq_map_data;
432 extern struct bio *bio_map_user_iov(struct request_queue *,
433                                     const struct iov_iter *, gfp_t);
434 extern void bio_unmap_user(struct bio *);
435 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
436                                 gfp_t);
437 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
438                                  gfp_t, int);
439 extern void bio_set_pages_dirty(struct bio *bio);
440 extern void bio_check_pages_dirty(struct bio *bio);
441 
442 void generic_start_io_acct(int rw, unsigned long sectors,
443                            struct hd_struct *part);
444 void generic_end_io_acct(int rw, struct hd_struct *part,
445                          unsigned long start_time);
446 
447 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
448 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
449 #endif
450 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
451 extern void bio_flush_dcache_pages(struct bio *bi);
452 #else
453 static inline void bio_flush_dcache_pages(struct bio *bi)
454 {
455 }
456 #endif
457 
458 extern void bio_copy_data(struct bio *dst, struct bio *src);
459 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
460 
461 extern struct bio *bio_copy_user_iov(struct request_queue *,
462                                      struct rq_map_data *,
463                                      const struct iov_iter *,
464                                      gfp_t);
465 extern int bio_uncopy_user(struct bio *);
466 void zero_fill_bio(struct bio *bio);
467 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
468 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
469 extern unsigned int bvec_nr_vecs(unsigned short idx);
470 
471 #ifdef CONFIG_BLK_CGROUP
472 int bio_associate_current(struct bio *bio);
473 void bio_disassociate_task(struct bio *bio);
474 #else   /* CONFIG_BLK_CGROUP */
475 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
476 static inline void bio_disassociate_task(struct bio *bio) { }
477 #endif  /* CONFIG_BLK_CGROUP */
478 
479 #ifdef CONFIG_HIGHMEM
480 /*
481  * remember never ever reenable interrupts between a bvec_kmap_irq and
482  * bvec_kunmap_irq!
483  */
484 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
485 {
486         unsigned long addr;
487 
488         /*
489          * might not be a highmem page, but the preempt/irq count
490          * balancing is a lot nicer this way
491          */
492         local_irq_save(*flags);
493         addr = (unsigned long) kmap_atomic(bvec->bv_page);
494 
495         BUG_ON(addr & ~PAGE_MASK);
496 
497         return (char *) addr + bvec->bv_offset;
498 }
499 
500 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
501 {
502         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
503 
504         kunmap_atomic((void *) ptr);
505         local_irq_restore(*flags);
506 }
507 
508 #else
509 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
510 {
511         return page_address(bvec->bv_page) + bvec->bv_offset;
512 }
513 
514 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
515 {
516         *flags = 0;
517 }
518 #endif
519 
520 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
521                                    unsigned long *flags)
522 {
523         return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
524 }
525 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
526 
527 #define bio_kmap_irq(bio, flags) \
528         __bio_kmap_irq((bio), (bio)->bi_iter, (flags))
529 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
530 
531 /*
532  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
533  *
534  * A bio_list anchors a singly-linked list of bios chained through the bi_next
535  * member of the bio.  The bio_list also caches the last list member to allow
536  * fast access to the tail.
537  */
538 struct bio_list {
539         struct bio *head;
540         struct bio *tail;
541 };
542 
543 static inline int bio_list_empty(const struct bio_list *bl)
544 {
545         return bl->head == NULL;
546 }
547 
548 static inline void bio_list_init(struct bio_list *bl)
549 {
550         bl->head = bl->tail = NULL;
551 }
552 
553 #define BIO_EMPTY_LIST  { NULL, NULL }
554 
555 #define bio_list_for_each(bio, bl) \
556         for (bio = (bl)->head; bio; bio = bio->bi_next)
557 
558 static inline unsigned bio_list_size(const struct bio_list *bl)
559 {
560         unsigned sz = 0;
561         struct bio *bio;
562 
563         bio_list_for_each(bio, bl)
564                 sz++;
565 
566         return sz;
567 }
568 
569 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
570 {
571         bio->bi_next = NULL;
572 
573         if (bl->tail)
574                 bl->tail->bi_next = bio;
575         else
576                 bl->head = bio;
577 
578         bl->tail = bio;
579 }
580 
581 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
582 {
583         bio->bi_next = bl->head;
584 
585         bl->head = bio;
586 
587         if (!bl->tail)
588                 bl->tail = bio;
589 }
590 
591 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
592 {
593         if (!bl2->head)
594                 return;
595 
596         if (bl->tail)
597                 bl->tail->bi_next = bl2->head;
598         else
599                 bl->head = bl2->head;
600 
601         bl->tail = bl2->tail;
602 }
603 
604 static inline void bio_list_merge_head(struct bio_list *bl,
605                                        struct bio_list *bl2)
606 {
607         if (!bl2->head)
608                 return;
609 
610         if (bl->head)
611                 bl2->tail->bi_next = bl->head;
612         else
613                 bl->tail = bl2->tail;
614 
615         bl->head = bl2->head;
616 }
617 
618 static inline struct bio *bio_list_peek(struct bio_list *bl)
619 {
620         return bl->head;
621 }
622 
623 static inline struct bio *bio_list_pop(struct bio_list *bl)
624 {
625         struct bio *bio = bl->head;
626 
627         if (bio) {
628                 bl->head = bl->head->bi_next;
629                 if (!bl->head)
630                         bl->tail = NULL;
631 
632                 bio->bi_next = NULL;
633         }
634 
635         return bio;
636 }
637 
638 static inline struct bio *bio_list_get(struct bio_list *bl)
639 {
640         struct bio *bio = bl->head;
641 
642         bl->head = bl->tail = NULL;
643 
644         return bio;
645 }
646 
647 /*
648  * bio_set is used to allow other portions of the IO system to
649  * allocate their own private memory pools for bio and iovec structures.
650  * These memory pools in turn all allocate from the bio_slab
651  * and the bvec_slabs[].
652  */
653 #define BIO_POOL_SIZE 2
654 #define BIOVEC_NR_POOLS 6
655 #define BIOVEC_MAX_IDX  (BIOVEC_NR_POOLS - 1)
656 
657 struct bio_set {
658         struct kmem_cache *bio_slab;
659         unsigned int front_pad;
660 
661         mempool_t *bio_pool;
662         mempool_t *bvec_pool;
663 #if defined(CONFIG_BLK_DEV_INTEGRITY)
664         mempool_t *bio_integrity_pool;
665         mempool_t *bvec_integrity_pool;
666 #endif
667 
668         /*
669          * Deadlock avoidance for stacking block drivers: see comments in
670          * bio_alloc_bioset() for details
671          */
672         spinlock_t              rescue_lock;
673         struct bio_list         rescue_list;
674         struct work_struct      rescue_work;
675         struct workqueue_struct *rescue_workqueue;
676 };
677 
678 struct biovec_slab {
679         int nr_vecs;
680         char *name;
681         struct kmem_cache *slab;
682 };
683 
684 /*
685  * a small number of entries is fine, not going to be performance critical.
686  * basically we just need to survive
687  */
688 #define BIO_SPLIT_ENTRIES 2
689 
690 #if defined(CONFIG_BLK_DEV_INTEGRITY)
691 
692 #define bip_for_each_vec(bvl, bip, iter)                                \
693         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
694 
695 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
696         for_each_bio(_bio)                                              \
697                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
698 
699 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
700 extern void bio_integrity_free(struct bio *);
701 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
702 extern bool bio_integrity_enabled(struct bio *bio);
703 extern int bio_integrity_prep(struct bio *);
704 extern void bio_integrity_endio(struct bio *, int);
705 extern void bio_integrity_advance(struct bio *, unsigned int);
706 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
707 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
708 extern int bioset_integrity_create(struct bio_set *, int);
709 extern void bioset_integrity_free(struct bio_set *);
710 extern void bio_integrity_init(void);
711 
712 #else /* CONFIG_BLK_DEV_INTEGRITY */
713 
714 static inline void *bio_integrity(struct bio *bio)
715 {
716         return NULL;
717 }
718 
719 static inline bool bio_integrity_enabled(struct bio *bio)
720 {
721         return false;
722 }
723 
724 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
725 {
726         return 0;
727 }
728 
729 static inline void bioset_integrity_free (struct bio_set *bs)
730 {
731         return;
732 }
733 
734 static inline int bio_integrity_prep(struct bio *bio)
735 {
736         return 0;
737 }
738 
739 static inline void bio_integrity_free(struct bio *bio)
740 {
741         return;
742 }
743 
744 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
745                                       gfp_t gfp_mask)
746 {
747         return 0;
748 }
749 
750 static inline void bio_integrity_advance(struct bio *bio,
751                                          unsigned int bytes_done)
752 {
753         return;
754 }
755 
756 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
757                                       unsigned int sectors)
758 {
759         return;
760 }
761 
762 static inline void bio_integrity_init(void)
763 {
764         return;
765 }
766 
767 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
768 {
769         return false;
770 }
771 
772 #endif /* CONFIG_BLK_DEV_INTEGRITY */
773 
774 #endif /* CONFIG_BLOCK */
775 #endif /* __LINUX_BIO_H */
776 

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