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