1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
27 /* All Rights Reserved */
28
29 /*
30 * University Copyright- Copyright (c) 1982, 1986, 1988
31 * The Regents of the University of California
32 * All Rights Reserved
33 *
34 * University Acknowledgment- Portions of this document are derived from
35 * software developed by the University of California, Berkeley, and its
36 * contributors.
37 */
38
39 #ifndef _SYS_BUF_H
40 #define _SYS_BUF_H
41
42 #include <sys/types32.h>
43 #include <sys/t_lock.h>
44 #include <sys/kstat.h>
45
46 #ifdef __cplusplus
47 extern "C" {
48 #endif
49
50 /*
51 * Each buffer in the pool is usually doubly linked into 2 lists:
52 * the device with which it is currently associated (always)
53 * and also on a list of blocks available for allocation
54 * for other use (usually).
55 * The latter list is kept in last-used order, and the two
56 * lists are doubly linked to make it easy to remove
57 * a buffer from one list when it was found by
58 * looking through the other.
59 * A buffer is on the available list, and is liable
60 * to be reassigned to another disk block, if and only
61 * if it is not marked BUSY. When a buffer is busy, the
62 * available-list pointers can be used for other purposes.
63 * Most drivers use the forward ptr as a link in their I/O active queue.
64 * A buffer header contains all the information required to perform I/O.
65 * Most of the routines which manipulate these things are in bio.c.
66 *
67 * There are a number of locks associated with the buffer management
68 * system.
69 * hbuf.b_lock: protects hash chains, buffer hdr freelists
70 * and delayed write freelist
71 * bfree_lock; protects the bfreelist structure
72 * bhdr_lock: protects the free header list
73 * blist_lock: protects b_list fields
74 * buf.b_sem: protects all remaining members in the buf struct
75 * buf.b_io: I/O synchronization variable
76 *
77 * A buffer header is never "locked" (b_sem) when it is on
78 * a "freelist" (bhdrlist or bfreelist avail lists).
79 */
80 typedef struct buf {
81 int b_flags; /* see defines below */
82 struct buf *b_forw; /* headed by d_tab of conf.c */
83 struct buf *b_back; /* " */
84 struct buf *av_forw; /* position on free list, */
85 struct buf *av_back; /* if not BUSY */
86 o_dev_t b_dev; /* OLD major+minor device name */
87 size_t b_bcount; /* transfer count */
88 union {
89 caddr_t b_addr; /* low order core address */
90 struct fs *b_fs; /* superblocks */
91 struct cg *b_cg; /* UFS cylinder group block */
92 struct dinode *b_dino; /* UFS ilist */
93 daddr32_t *b_daddr; /* disk blocks */
94 } b_un;
95
96 lldaddr_t _b_blkno; /* block # on device (union) */
97 #define b_lblkno _b_blkno._f
98 #ifdef _LP64
99 #define b_blkno _b_blkno._f
100 #else
101 #define b_blkno _b_blkno._p._l
102 #endif /* _LP64 */
103
104 char b_obs1; /* obsolete */
105 size_t b_resid; /* words not transferred after error */
106 clock_t b_start; /* request start time */
107 struct proc *b_proc; /* process doing physical or swap I/O */
108 struct page *b_pages; /* page list for PAGEIO */
109 clock_t b_obs2; /* obsolete */
110 /* Begin new stuff */
111 #define b_actf av_forw
112 #define b_actl av_back
113 #define b_active b_bcount
114 #define b_errcnt b_resid
115 size_t b_bufsize; /* size of allocated buffer */
116 int (*b_iodone)(struct buf *); /* function called by iodone */
117 struct vnode *b_vp; /* vnode associated with block */
118 struct buf *b_chain; /* chain together all buffers here */
119 int b_obs3; /* obsolete */
120 int b_error; /* expanded error field */
121 void *b_private; /* "opaque" driver private area */
122 dev_t b_edev; /* expanded dev field */
123 ksema_t b_sem; /* Exclusive access to buf */
124 ksema_t b_io; /* I/O Synchronization */
125 struct buf *b_list; /* List of potential B_DELWRI bufs */
126 struct page **b_shadow; /* shadow page list */
127 void *b_dip; /* device info pointer */
128 struct vnode *b_file; /* file associated with this buffer */
129 offset_t b_offset; /* offset in file assoc. with buffer */
130 } buf_t;
131
132 /*
133 * Bufhd structures used at the head of the hashed buffer queues.
134 * We only need seven words for this, so this abbreviated
135 * definition saves some space.
136 */
137 struct diskhd {
138 int b_flags; /* not used, needed for consistency */
139 struct buf *b_forw, *b_back; /* queue of unit queues */
140 struct buf *av_forw, *av_back; /* queue of bufs for this unit */
141 o_dev_t b_dev; /* OLD major+minor device name */
142 size_t b_bcount; /* transfer count */
143 };
144
145
146 /*
147 * Statistics on the buffer cache
148 */
149 struct biostats {
150 kstat_named_t bio_lookup; /* requests to assign buffer */
151 kstat_named_t bio_hit; /* buffer already associated with blk */
152 kstat_named_t bio_bufwant; /* kmem_allocs NOSLEEP failed new buf */
153 kstat_named_t bio_bufwait; /* kmem_allocs with KM_SLEEP for buf */
154 kstat_named_t bio_bufbusy; /* buffer locked by someone else */
155 kstat_named_t bio_bufdup; /* duplicate buffer found for block */
156 };
157
158 /*
159 * These flags are kept in b_flags.
160 * The first group is part of the DDI
161 */
162 #define B_BUSY 0x0001 /* not on av_forw/back list */
163 #define B_DONE 0x0002 /* transaction finished */
164 #define B_ERROR 0x0004 /* transaction aborted */
165 #define B_PAGEIO 0x0010 /* do I/O to pages on bp->p_pages */
166 #define B_PHYS 0x0020 /* Physical IO potentially using UNIBUS map */
167 #define B_READ 0x0040 /* read when I/O occurs */
168 #define B_WRITE 0x0100 /* non-read pseudo-flag */
169
170 /* Not part of the DDI */
171 #define B_WANTED 0x0080 /* issue wakeup when BUSY goes off */
172 #define B_AGE 0x000200 /* delayed write for correct aging */
173 #define B_ASYNC 0x000400 /* don't wait for I/O completion */
174 #define B_DELWRI 0x000800 /* delayed write-wait til buf needed */
175 #define B_STALE 0x001000 /* on av_* list; invalid contents */
176 #define B_DONTNEED 0x002000 /* after write, need not be cached */
177 #define B_REMAPPED 0x004000 /* buffer is kernel addressable */
178 #define B_FREE 0x008000 /* free page when done */
179 #define B_INVAL 0x010000 /* destroy page when done */
180 #define B_FORCE 0x020000 /* semi-permanent removal from cache */
181 #define B_NOCACHE 0x080000 /* don't cache block when released */
182 #define B_TRUNC 0x100000 /* truncate page without I/O */
183 #define B_SHADOW 0x200000 /* is b_shadow field valid? */
184 #define B_RETRYWRI 0x400000 /* retry write til works or bfinval */
185 #define B_FAILFAST 0x1000000 /* Fail promptly if device goes away */
186 #define B_STARTED 0x2000000 /* io:::start probe called for buf */
187 #define B_ABRWRITE 0x4000000 /* Application based recovery active */
188 #define B_PAGE_NOWAIT 0x8000000 /* Skip the page if it is locked */
189
190 /*
191 * There is some confusion over the meaning of B_FREE and B_INVAL and what
192 * the use of one over the other implies.
193 *
194 * In both cases, when we are done with the page (buffer) we want to free
195 * up the page. In the case of B_FREE, the page will go to the cachelist.
196 * In the case of B_INVAL, the page will be destroyed (hashed out of it's
197 * vnode) and placed on the freelist. Beyond this, there is no difference
198 * between the sole use of these two flags. In both cases, IO will be done
199 * if the page is not yet committed to storage.
200 *
201 * In order to discard pages without writing them back, (B_INVAL | B_TRUNC)
202 * should be used.
203 *
204 * Use (B_INVAL | B_FORCE) to force the page to be destroyed even if we
205 * could not successfuly write out the page.
206 */
207
208 /*
209 * Insq/Remq for the buffer hash lists.
210 */
211 #define bremhash(bp) { \
212 ASSERT((bp)->b_forw != NULL); \
213 ASSERT((bp)->b_back != NULL); \
214 (bp)->b_back->b_forw = (bp)->b_forw; \
215 (bp)->b_forw->b_back = (bp)->b_back; \
216 (bp)->b_forw = (bp)->b_back = NULL; \
217 }
218 #define binshash(bp, dp) { \
219 ASSERT((bp)->b_forw == NULL); \
220 ASSERT((bp)->b_back == NULL); \
221 ASSERT((dp)->b_forw != NULL); \
222 ASSERT((dp)->b_back != NULL); \
223 (bp)->b_forw = (dp)->b_forw; \
224 (bp)->b_back = (dp); \
225 (dp)->b_forw->b_back = (bp); \
226 (dp)->b_forw = (bp); \
227 }
228
229
230 /*
231 * The hash structure maintains two lists:
232 *
233 * 1) The hash list of buffers (b_forw & b_back)
234 * 2) The LRU free list of buffers on this hash bucket (av_forw & av_back)
235 *
236 * The dwbuf structure keeps a list of delayed write buffers per hash bucket
237 * hence there are exactly the same number of dwbuf structures as there are
238 * the hash buckets (hbuf structures) in the system.
239 *
240 * The number of buffers on the freelist may not be equal to the number of
241 * buffers on the hash list. That is because when buffers are busy they are
242 * taken off the freelist but not off the hash list. "b_length" field keeps
243 * track of the number of free buffers (including delayed writes ones) on
244 * the hash bucket. The "b_lock" mutex protects the free list as well as
245 * the hash list. It also protects the counter "b_length".
246 *
247 * Enties b_forw, b_back, av_forw & av_back must be at the same offset
248 * as the ones in buf structure.
249 */
250 struct hbuf {
251 int b_flags;
252
253 struct buf *b_forw; /* hash list forw pointer */
254 struct buf *b_back; /* hash list back pointer */
255
256 struct buf *av_forw; /* free list forw pointer */
257 struct buf *av_back; /* free list back pointer */
258
259 int b_length; /* # of entries on free list */
260 kmutex_t b_lock; /* lock to protect this structure */
261 };
262
263
264 /*
265 * The delayed list pointer entries should match with the buf strcuture.
266 */
267 struct dwbuf {
268 int b_flags; /* not used */
269
270 struct buf *b_forw; /* not used */
271 struct buf *b_back; /* not used */
272
273 struct buf *av_forw; /* delayed write forw pointer */
274 struct buf *av_back; /* delayed write back pointer */
275 };
276
277
278 /*
279 * Unlink a buffer from the available (free or delayed write) list and mark
280 * it busy (internal interface).
281 */
282 #define notavail(bp) \
283 {\
284 ASSERT(SEMA_HELD(&bp->b_sem)); \
285 ASSERT((bp)->av_forw != NULL); \
286 ASSERT((bp)->av_back != NULL); \
287 ASSERT((bp)->av_forw != (bp)); \
288 ASSERT((bp)->av_back != (bp)); \
289 (bp)->av_back->av_forw = (bp)->av_forw; \
290 (bp)->av_forw->av_back = (bp)->av_back; \
291 (bp)->b_flags |= B_BUSY; \
292 (bp)->av_forw = (bp)->av_back = NULL; \
293 }
294
295 #if defined(_KERNEL)
296 /*
297 * Macros to avoid the extra function call needed for binary compat.
298 *
299 * B_RETRYWRI is not included in clear_flags for BWRITE(), BWRITE2(),
300 * or brwrite() so that the retry operation is persistent until the
301 * write either succeeds or the buffer is bfinval()'d.
302 *
303 */
304 #define BREAD(dev, blkno, bsize) \
305 bread_common(/* ufsvfsp */ NULL, dev, blkno, bsize)
306
307 #define BWRITE(bp) \
308 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 0, \
309 /* do_relse */ 1, \
310 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI))
311
312 #define BWRITE2(bp) \
313 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 1, \
314 /* do_relse */ 0, \
315 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI))
316
317 #define GETBLK(dev, blkno, bsize) \
318 getblk_common(/* ufsvfsp */ NULL, dev, blkno, bsize, /* errflg */ 0)
319
320
321 /*
322 * Macros for new retry write interfaces.
323 */
324
325 /*
326 * Same as bdwrite() except write failures are retried.
327 */
328 #define bdrwrite(bp) { \
329 (bp)->b_flags |= B_RETRYWRI; \
330 bdwrite((bp)); \
331 }
332
333 /*
334 * Same as bwrite() except write failures are retried.
335 */
336 #define brwrite(bp) { \
337 (bp)->b_flags |= B_RETRYWRI; \
338 bwrite_common((bp), /* force_wait */ 0, /* do_relse */ 1, \
339 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)); \
340 }
341
342 extern struct hbuf *hbuf; /* Hash table */
343 extern struct dwbuf *dwbuf; /* delayed write hash table */
344 extern struct buf *buf; /* The buffer pool itself */
345 extern struct buf bfreelist; /* head of available list */
346
347 extern void (*bio_lufs_strategy)(void *, buf_t *); /* UFS Logging */
348 extern void (*bio_snapshot_strategy)(void *, buf_t *); /* UFS snapshots */
349
350 int bcheck(dev_t, struct buf *);
351 int iowait(struct buf *);
352 int hash2ints(int x, int y);
353 int bio_busy(int);
354 int biowait(struct buf *);
355 int biomodified(struct buf *);
356 int geterror(struct buf *);
357 void minphys(struct buf *);
358 /*
359 * ufsvfsp is declared as a void * to avoid having everyone that uses
360 * this header file include sys/fs/ufs_inode.h.
361 */
362 void bwrite_common(void *ufsvfsp, struct buf *, int force_wait,
363 int do_relse, int clear_flags);
364 void bwrite(struct buf *);
365 void bwrite2(struct buf *);
366 void bdwrite(struct buf *);
367 void bawrite(struct buf *);
368 void brelse(struct buf *);
369 void iodone(struct buf *);
370 void clrbuf(struct buf *);
371 void bflush(dev_t);
372 void blkflush(dev_t, daddr_t);
373 void binval(dev_t);
374 int bfinval(dev_t, int);
375 void binit(void);
376 void biodone(struct buf *);
377 void bioinit(struct buf *);
378 void biofini(struct buf *);
379 void bp_mapin(struct buf *);
380 void *bp_mapin_common(struct buf *, int);
381 void bp_mapout(struct buf *);
382 int bp_copyin(struct buf *, void *, offset_t, size_t);
383 int bp_copyout(void *, struct buf *, offset_t, size_t);
384 void bp_init(size_t, uint_t);
385 int bp_color(struct buf *);
386 void pageio_done(struct buf *);
387 struct buf *bread(dev_t, daddr_t, long);
388 struct buf *bread_common(void *, dev_t, daddr_t, long);
389 struct buf *breada(dev_t, daddr_t, daddr_t, long);
390 struct buf *getblk(dev_t, daddr_t, long);
391 struct buf *getblk_common(void *, dev_t, daddr_t, long, int);
392 struct buf *ngeteblk(long);
393 struct buf *geteblk(void);
394 struct buf *pageio_setup(struct page *, size_t, struct vnode *, int);
395 void bioerror(struct buf *bp, int error);
396 void bioreset(struct buf *bp);
397 struct buf *bioclone(struct buf *, off_t, size_t, dev_t, daddr_t,
398 int (*)(struct buf *), struct buf *, int);
399 size_t biosize(void);
400 #endif /* defined(_KERNEL) */
401
402 #ifdef __cplusplus
403 }
404 #endif
405
406 #endif /* _SYS_BUF_H */