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
27 /* Platforms may set this to teach the BIO layer about IOMMU hardware. */
28 #include <asm/io.h>
29
30 #if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
31 #define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
32 #define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
33 #else
34 #define BIOVEC_VIRT_START_SIZE(x) 0
35 #define BIOVEC_VIRT_OVERSIZE(x) 0
36 #endif
37
38 #ifndef BIO_VMERGE_BOUNDARY
39 #define BIO_VMERGE_BOUNDARY 0
40 #endif
41
42 #define BIO_DEBUG
43
44 #ifdef BIO_DEBUG
45 #define BIO_BUG_ON BUG_ON
46 #else
47 #define BIO_BUG_ON
48 #endif
49
50 #define BIO_MAX_PAGES 256
51 #define BIO_MAX_SIZE (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
52 #define BIO_MAX_SECTORS (BIO_MAX_SIZE >> 9)
53
54 /*
55 * was unsigned short, but we might as well be ready for > 64kB I/O pages
56 */
57 struct bio_vec {
58 struct page *bv_page;
59 unsigned int bv_len;
60 unsigned int bv_offset;
61 };
62
63 struct bio_set;
64 struct bio;
65 typedef int (bio_end_io_t) (struct bio *, unsigned int, int);
66 typedef void (bio_destructor_t) (struct bio *);
67
68 /*
69 * main unit of I/O for the block layer and lower layers (ie drivers and
70 * stacking drivers)
71 */
72 struct bio {
73 sector_t bi_sector;
74 struct bio *bi_next; /* request queue link */
75 struct block_device *bi_bdev;
76 unsigned long bi_flags; /* status, command, etc */
77 unsigned long bi_rw; /* bottom bits READ/WRITE,
78 * top bits priority
79 */
80
81 unsigned short bi_vcnt; /* how many bio_vec's */
82 unsigned short bi_idx; /* current index into bvl_vec */
83
84 /* Number of segments in this BIO after
85 * physical address coalescing is performed.
86 */
87 unsigned short bi_phys_segments;
88
89 /* Number of segments after physical and DMA remapping
90 * hardware coalescing is performed.
91 */
92 unsigned short bi_hw_segments;
93
94 unsigned int bi_size; /* residual I/O count */
95
96 /*
97 * To keep track of the max hw size, we account for the
98 * sizes of the first and last virtually mergeable segments
99 * in this bio
100 */
101 unsigned int bi_hw_front_size;
102 unsigned int bi_hw_back_size;
103
104 unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
105
106 struct bio_vec *bi_io_vec; /* the actual vec list */
107
108 bio_end_io_t *bi_end_io;
109 atomic_t bi_cnt; /* pin count */
110
111 void *bi_private;
112
113 bio_destructor_t *bi_destructor; /* destructor */
114 };
115
116 /*
117 * bio flags
118 */
119 #define BIO_UPTODATE 0 /* ok after I/O completion */
120 #define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */
121 #define BIO_EOF 2 /* out-out-bounds error */
122 #define BIO_SEG_VALID 3 /* nr_hw_seg valid */
123 #define BIO_CLONED 4 /* doesn't own data */
124 #define BIO_BOUNCED 5 /* bio is a bounce bio */
125 #define BIO_USER_MAPPED 6 /* contains user pages */
126 #define BIO_EOPNOTSUPP 7 /* not supported */
127 #define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
128
129 /*
130 * top 4 bits of bio flags indicate the pool this bio came from
131 */
132 #define BIO_POOL_BITS (4)
133 #define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
134 #define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
135 #define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)
136
137 /*
138 * bio bi_rw flags
139 *
140 * bit 0 -- read (not set) or write (set)
141 * bit 1 -- rw-ahead when set
142 * bit 2 -- barrier
143 * bit 3 -- fail fast, don't want low level driver retries
144 * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
145 */
146 #define BIO_RW 0
147 #define BIO_RW_AHEAD 1
148 #define BIO_RW_BARRIER 2
149 #define BIO_RW_FAILFAST 3
150 #define BIO_RW_SYNC 4
151
152 /*
153 * upper 16 bits of bi_rw define the io priority of this bio
154 */
155 #define BIO_PRIO_SHIFT (8 * sizeof(unsigned long) - IOPRIO_BITS)
156 #define bio_prio(bio) ((bio)->bi_rw >> BIO_PRIO_SHIFT)
157 #define bio_prio_valid(bio) ioprio_valid(bio_prio(bio))
158
159 #define bio_set_prio(bio, prio) do { \
160 WARN_ON(prio >= (1 << IOPRIO_BITS)); \
161 (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1); \
162 (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT); \
163 } while (0)
164
165 /*
166 * various member access, note that bio_data should of course not be used
167 * on highmem page vectors
168 */
169 #define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
170 #define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx)
171 #define bio_page(bio) bio_iovec((bio))->bv_page
172 #define bio_offset(bio) bio_iovec((bio))->bv_offset
173 #define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx)
174 #define bio_sectors(bio) ((bio)->bi_size >> 9)
175 #define bio_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9)
176 #define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio)))
177 #define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
178 #define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC))
179 #define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
180 #define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
181
182 /*
183 * will die
184 */
185 #define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
186 #define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
187
188 /*
189 * queues that have highmem support enabled may still need to revert to
190 * PIO transfers occasionally and thus map high pages temporarily. For
191 * permanent PIO fall back, user is probably better off disabling highmem
192 * I/O completely on that queue (see ide-dma for example)
193 */
194 #define __bio_kmap_atomic(bio, idx, kmtype) \
195 (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) + \
196 bio_iovec_idx((bio), (idx))->bv_offset)
197
198 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
199
200 /*
201 * merge helpers etc
202 */
203
204 #define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
205 #define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx)
206
207 /*
208 * allow arch override, for eg virtualized architectures (put in asm/io.h)
209 */
210 #ifndef BIOVEC_PHYS_MERGEABLE
211 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \
212 ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
213 #endif
214
215 #define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \
216 ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
217 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
218 (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
219 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
220 __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
221 #define BIO_SEG_BOUNDARY(q, b1, b2) \
222 BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
223
224 #define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO)
225
226 /*
227 * drivers should not use the __ version unless they _really_ want to
228 * run through the entire bio and not just pending pieces
229 */
230 #define __bio_for_each_segment(bvl, bio, i, start_idx) \
231 for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \
232 i < (bio)->bi_vcnt; \
233 bvl++, i++)
234
235 #define bio_for_each_segment(bvl, bio, i) \
236 __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
237
238 /*
239 * get a reference to a bio, so it won't disappear. the intended use is
240 * something like:
241 *
242 * bio_get(bio);
243 * submit_bio(rw, bio);
244 * if (bio->bi_flags ...)
245 * do_something
246 * bio_put(bio);
247 *
248 * without the bio_get(), it could potentially complete I/O before submit_bio
249 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
250 * runs
251 */
252 #define bio_get(bio) atomic_inc(&(bio)->bi_cnt)
253
254
255 /*
256 * A bio_pair is used when we need to split a bio.
257 * This can only happen for a bio that refers to just one
258 * page of data, and in the unusual situation when the
259 * page crosses a chunk/device boundary
260 *
261 * The address of the master bio is stored in bio1.bi_private
262 * The address of the pool the pair was allocated from is stored
263 * in bio2.bi_private
264 */
265 struct bio_pair {
266 struct bio bio1, bio2;
267 struct bio_vec bv1, bv2;
268 atomic_t cnt;
269 int error;
270 };
271 extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
272 int first_sectors);
273 extern mempool_t *bio_split_pool;
274 extern void bio_pair_release(struct bio_pair *dbio);
275
276 extern struct bio_set *bioset_create(int, int, int);
277 extern void bioset_free(struct bio_set *);
278
279 extern struct bio *bio_alloc(gfp_t, int);
280 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
281 extern void bio_put(struct bio *);
282 extern void bio_free(struct bio *, struct bio_set *);
283
284 extern void bio_endio(struct bio *, unsigned int, int);
285 struct request_queue;
286 extern int bio_phys_segments(struct request_queue *, struct bio *);
287 extern int bio_hw_segments(struct request_queue *, struct bio *);
288
289 extern void __bio_clone(struct bio *, struct bio *);
290 extern struct bio *bio_clone(struct bio *, gfp_t);
291
292 extern void bio_init(struct bio *);
293
294 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
295 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
296 unsigned int, unsigned int);
297 extern int bio_get_nr_vecs(struct block_device *);
298 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
299 unsigned long, unsigned int, int);
300 struct sg_iovec;
301 extern struct bio *bio_map_user_iov(struct request_queue *,
302 struct block_device *,
303 struct sg_iovec *, int, int);
304 extern void bio_unmap_user(struct bio *);
305 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
306 gfp_t);
307 extern void bio_set_pages_dirty(struct bio *bio);
308 extern void bio_check_pages_dirty(struct bio *bio);
309 extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
310 extern int bio_uncopy_user(struct bio *);
311 void zero_fill_bio(struct bio *bio);
312
313 #ifdef CONFIG_HIGHMEM
314 /*
315 * remember to add offset! and never ever reenable interrupts between a
316 * bvec_kmap_irq and bvec_kunmap_irq!!
317 *
318 * This function MUST be inlined - it plays with the CPU interrupt flags.
319 */
bvec_kmap_irq(struct bio_vec * bvec,unsigned long * flags)320 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
321 {
322 unsigned long addr;
323
324 /*
325 * might not be a highmem page, but the preempt/irq count
326 * balancing is a lot nicer this way
327 */
328 local_irq_save(*flags);
329 addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
330
331 BUG_ON(addr & ~PAGE_MASK);
332
333 return (char *) addr + bvec->bv_offset;
334 }
335
bvec_kunmap_irq(char * buffer,unsigned long * flags)336 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
337 {
338 unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
339
340 kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
341 local_irq_restore(*flags);
342 }
343
344 #else
345 #define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + (bvec)->bv_offset)
346 #define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0)
347 #endif
348
__bio_kmap_irq(struct bio * bio,unsigned short idx,unsigned long * flags)349 static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
350 unsigned long *flags)
351 {
352 return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
353 }
354 #define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags)
355
356 #define bio_kmap_irq(bio, flags) \
357 __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
358 #define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags)
359
360 #endif /* __LINUX_BIO_H */
361