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 * Copyright 2017 RackTop Systems.
26 */
27
28 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
29 /* All Rights Reserved */
30
31 /*
32 * University Copyright- Copyright (c) 1982, 1986, 1988
33 * The Regents of the University of California
34 * All Rights Reserved
35 *
36 * University Acknowledgment- Portions of this document are derived from
37 * software developed by the University of California, Berkeley, and its
38 * contributors.
39 */
40
41 #ifndef _SYS_BUF_H
42 #define _SYS_BUF_H
43
44 #include <sys/types32.h>
45 #include <sys/t_lock.h>
46 #include <sys/kstat.h>
47
48 #ifdef __cplusplus
49 extern "C" {
50 #endif
51
52 /*
53 * Each buffer in the pool is usually doubly linked into 2 lists:
54 * the device with which it is currently associated (always)
55 * and also on a list of blocks available for allocation
56 * for other use (usually).
57 * The latter list is kept in last-used order, and the two
58 * lists are doubly linked to make it easy to remove
59 * a buffer from one list when it was found by
60 * looking through the other.
61 * A buffer is on the available list, and is liable
62 * to be reassigned to another disk block, if and only
63 * if it is not marked BUSY. When a buffer is busy, the
64 * available-list pointers can be used for other purposes.
65 * Most drivers use the forward ptr as a link in their I/O active queue.
66 * A buffer header contains all the information required to perform I/O.
67 * Most of the routines which manipulate these things are in bio.c.
68 *
69 * There are a number of locks associated with the buffer management
70 * system.
71 * hbuf.b_lock: protects hash chains, buffer hdr freelists
72 * and delayed write freelist
73 * bfree_lock; protects the bfreelist structure
74 * bhdr_lock: protects the free header list
75 * blist_lock: protects b_list fields
76 * buf.b_sem: protects all remaining members in the buf struct
77 * buf.b_io: I/O synchronization variable
78 *
79 * A buffer header is never "locked" (b_sem) when it is on
80 * a "freelist" (bhdrlist or bfreelist avail lists).
81 */
82 typedef struct buf {
83 int b_flags; /* see defines below */
84 struct buf *b_forw; /* headed by d_tab of conf.c */
85 struct buf *b_back; /* " */
86 struct buf *av_forw; /* position on free list, */
87 struct buf *av_back; /* if not BUSY */
88 o_dev_t b_dev; /* OLD major+minor device name */
89 size_t b_bcount; /* transfer count */
90 union {
91 caddr_t b_addr; /* low order core address */
92 struct fs *b_fs; /* superblocks */
93 struct cg *b_cg; /* UFS cylinder group block */
94 struct dinode *b_dino; /* UFS ilist */
95 daddr32_t *b_daddr; /* disk blocks */
96 } b_un;
97
98 lldaddr_t _b_blkno; /* block # on device (union) */
99 #define b_lblkno _b_blkno._f
100 #ifdef _LP64
101 #define b_blkno _b_blkno._f
102 #else
103 #define b_blkno _b_blkno._p._l
104 #endif /* _LP64 */
105
106 char b_obs1; /* obsolete */
107 size_t b_resid; /* words not transferred after error */
108 clock_t b_start; /* request start time */
109 struct proc *b_proc; /* process doing physical or swap I/O */
110 struct page *b_pages; /* page list for PAGEIO */
111 clock_t b_obs2; /* obsolete */
112 /* Begin new stuff */
113 #define b_actf av_forw
114 #define b_actl av_back
115 #define b_active b_bcount
116 #define b_errcnt b_resid
117 size_t b_bufsize; /* size of allocated buffer */
118 int (*b_iodone)(struct buf *); /* function called by iodone */
119 struct vnode *b_vp; /* vnode associated with block */
120 struct buf *b_chain; /* chain together all buffers here */
121 int b_obs3; /* obsolete */
122 int b_error; /* expanded error field */
123 void *b_private; /* "opaque" driver private area */
124 dev_t b_edev; /* expanded dev field */
125 ksema_t b_sem; /* Exclusive access to buf */
126 ksema_t b_io; /* I/O Synchronization */
127 struct buf *b_list; /* List of potential B_DELWRI bufs */
128 struct page **b_shadow; /* shadow page list */
129 void *b_dip; /* device info pointer */
130 struct vnode *b_file; /* file associated with this buffer */
131 offset_t b_offset; /* offset in file assoc. with buffer */
132 } buf_t;
133
134 /*
135 * Bufhd structures used at the head of the hashed buffer queues.
136 * We only need seven words for this, so this abbreviated
137 * definition saves some space.
138 */
139 struct diskhd {
140 int b_flags; /* not used, needed for consistency */
141 struct buf *b_forw, *b_back; /* queue of unit queues */
142 struct buf *av_forw, *av_back; /* queue of bufs for this unit */
143 o_dev_t b_dev; /* OLD major+minor device name */
144 size_t b_bcount; /* transfer count */
145 };
146
147
148 /*
149 * Statistics on the buffer cache
150 */
151 struct biostats {
152 kstat_named_t bio_lookup; /* requests to assign buffer */
153 kstat_named_t bio_hit; /* buffer already associated with blk */
154 kstat_named_t bio_bufwant; /* kmem_allocs NOSLEEP failed new buf */
155 kstat_named_t bio_bufwait; /* kmem_allocs with KM_SLEEP for buf */
156 kstat_named_t bio_bufbusy; /* buffer locked by someone else */
157 kstat_named_t bio_bufdup; /* duplicate buffer found for block */
158 };
159
160 /*
161 * These flags are kept in b_flags.
162 * The first group is part of the DDI
163 */
164 #define B_BUSY 0x0001 /* not on av_forw/back list */
165 #define B_DONE 0x0002 /* transaction finished */
166 #define B_ERROR 0x0004 /* transaction aborted */
167 #define B_PAGEIO 0x0010 /* do I/O to pages on bp->p_pages */
168 #define B_PHYS 0x0020 /* Physical IO potentially using UNIBUS map */
169 #define B_READ 0x0040 /* read when I/O occurs */
170 #define B_WRITE 0x0100 /* non-read pseudo-flag */
171
172 /* Not part of the DDI */
173 #define B_WANTED 0x0080 /* issue wakeup when BUSY goes off */
174 #define B_AGE 0x000200 /* delayed write for correct aging */
175 #define B_ASYNC 0x000400 /* don't wait for I/O completion */
176 #define B_DELWRI 0x000800 /* delayed write-wait til buf needed */
177 #define B_STALE 0x001000 /* on av_* list; invalid contents */
178 #define B_DONTNEED 0x002000 /* after write, need not be cached */
179 #define B_REMAPPED 0x004000 /* buffer is kernel addressable */
180 #define B_FREE 0x008000 /* free page when done */
181 #define B_INVAL 0x010000 /* destroy page when done */
182 #define B_FORCE 0x020000 /* semi-permanent removal from cache */
183 #define B_NOCACHE 0x080000 /* don't cache block when released */
184 #define B_TRUNC 0x100000 /* truncate page without I/O */
185 #define B_SHADOW 0x200000 /* is b_shadow field valid? */
186 #define B_RETRYWRI 0x400000 /* retry write til works or bfinval */
187 #define B_FAILFAST 0x1000000 /* Fail promptly if device goes away */
188 #define B_STARTED 0x2000000 /* io:::start probe called for buf */
189 #define B_ABRWRITE 0x4000000 /* Application based recovery active */
190 #define B_PAGE_NOWAIT 0x8000000 /* Skip the page if it is locked */
191
192 /*
193 * There is some confusion over the meaning of B_FREE and B_INVAL and what
194 * the use of one over the other implies.
195 *
196 * In both cases, when we are done with the page (buffer) we want to free
197 * up the page. In the case of B_FREE, the page will go to the cachelist.
198 * In the case of B_INVAL, the page will be destroyed (hashed out of it's
199 * vnode) and placed on the freelist. Beyond this, there is no difference
200 * between the sole use of these two flags. In both cases, IO will be done
201 * if the page is not yet committed to storage.
202 *
203 * In order to discard pages without writing them back, (B_INVAL | B_TRUNC)
204 * should be used.
205 *
206 * Use (B_INVAL | B_FORCE) to force the page to be destroyed even if we
207 * could not successfuly write out the page.
208 */
209
210 /*
211 * Insq/Remq for the buffer hash lists.
212 */
213 #define bremhash(bp) { \
214 ASSERT((bp)->b_forw != NULL); \
215 ASSERT((bp)->b_back != NULL); \
216 (bp)->b_back->b_forw = (bp)->b_forw; \
217 (bp)->b_forw->b_back = (bp)->b_back; \
218 (bp)->b_forw = (bp)->b_back = NULL; \
219 }
220 #define binshash(bp, dp) { \
221 ASSERT((bp)->b_forw == NULL); \
222 ASSERT((bp)->b_back == NULL); \
223 ASSERT((dp)->b_forw != NULL); \
224 ASSERT((dp)->b_back != NULL); \
225 (bp)->b_forw = (dp)->b_forw; \
226 (bp)->b_back = (dp); \
227 (dp)->b_forw->b_back = (bp); \
228 (dp)->b_forw = (bp); \
229 }
230
231
232 /*
233 * The hash structure maintains two lists:
234 *
235 * 1) The hash list of buffers (b_forw & b_back)
236 * 2) The LRU free list of buffers on this hash bucket (av_forw & av_back)
237 *
238 * The dwbuf structure keeps a list of delayed write buffers per hash bucket
239 * hence there are exactly the same number of dwbuf structures as there are
240 * the hash buckets (hbuf structures) in the system.
241 *
242 * The number of buffers on the freelist may not be equal to the number of
243 * buffers on the hash list. That is because when buffers are busy they are
244 * taken off the freelist but not off the hash list. "b_length" field keeps
245 * track of the number of free buffers (including delayed writes ones) on
246 * the hash bucket. The "b_lock" mutex protects the free list as well as
247 * the hash list. It also protects the counter "b_length".
248 *
249 * Enties b_forw, b_back, av_forw & av_back must be at the same offset
250 * as the ones in buf structure.
251 */
252 struct hbuf {
253 int b_flags;
254
255 struct buf *b_forw; /* hash list forw pointer */
256 struct buf *b_back; /* hash list back pointer */
257
258 struct buf *av_forw; /* free list forw pointer */
259 struct buf *av_back; /* free list back pointer */
260
261 int b_length; /* # of entries on free list */
262 kmutex_t b_lock; /* lock to protect this structure */
263 };
264
265
266 /*
267 * The delayed list pointer entries should match with the buf strcuture.
268 */
269 struct dwbuf {
270 int b_flags; /* not used */
271
272 struct buf *b_forw; /* not used */
273 struct buf *b_back; /* not used */
274
275 struct buf *av_forw; /* delayed write forw pointer */
276 struct buf *av_back; /* delayed write back pointer */
277 };
278
279
280 /*
281 * Unlink a buffer from the available (free or delayed write) list and mark
282 * it busy (internal interface).
283 */
284 #define notavail(bp) \
285 {\
286 ASSERT(SEMA_HELD(&bp->b_sem)); \
287 ASSERT((bp)->av_forw != NULL); \
288 ASSERT((bp)->av_back != NULL); \
289 ASSERT((bp)->av_forw != (bp)); \
290 ASSERT((bp)->av_back != (bp)); \
291 (bp)->av_back->av_forw = (bp)->av_forw; \
292 (bp)->av_forw->av_back = (bp)->av_back; \
293 (bp)->b_flags |= B_BUSY; \
294 (bp)->av_forw = (bp)->av_back = NULL; \
295 }
296
297 #if defined(_KERNEL) || defined(_FAKE_KERNEL)
298 /*
299 * Macros to avoid the extra function call needed for binary compat.
300 *
301 * B_RETRYWRI is not included in clear_flags for BWRITE(), BWRITE2(),
302 * or brwrite() so that the retry operation is persistent until the
303 * write either succeeds or the buffer is bfinval()'d.
304 *
305 */
306 #define BREAD(dev, blkno, bsize) \
307 bread_common(/* ufsvfsp */ NULL, dev, blkno, bsize)
308
309 #define BWRITE(bp) \
310 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 0, \
311 /* do_relse */ 1, \
312 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI))
313
314 #define BWRITE2(bp) \
315 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 1, \
316 /* do_relse */ 0, \
317 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI))
318
319 #define GETBLK(dev, blkno, bsize) \
320 getblk_common(/* ufsvfsp */ NULL, dev, blkno, bsize, /* errflg */ 0)
321
322
323 /*
324 * Macros for new retry write interfaces.
325 */
326
327 /*
328 * Same as bdwrite() except write failures are retried.
329 */
330 #define bdrwrite(bp) { \
331 (bp)->b_flags |= B_RETRYWRI; \
332 bdwrite((bp)); \
333 }
334
335 /*
336 * Same as bwrite() except write failures are retried.
337 */
338 #define brwrite(bp) { \
339 (bp)->b_flags |= B_RETRYWRI; \
340 bwrite_common((bp), /* force_wait */ 0, /* do_relse */ 1, \
341 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)); \
342 }
343
344 extern struct hbuf *hbuf; /* Hash table */
345 extern struct dwbuf *dwbuf; /* delayed write hash table */
346 extern struct buf *buf; /* The buffer pool itself */
347 extern struct buf bfreelist; /* head of available list */
348
349 extern void (*bio_lufs_strategy)(void *, buf_t *); /* UFS Logging */
350 extern void (*bio_snapshot_strategy)(void *, buf_t *); /* UFS snapshots */
351
352 int bcheck(dev_t, struct buf *);
353 int iowait(struct buf *);
354 int hash2ints(int x, int y);
355 int bio_busy(int);
356 int biowait(struct buf *);
357 int biomodified(struct buf *);
358 int geterror(struct buf *);
359 void minphys(struct buf *);
360 /*
361 * ufsvfsp is declared as a void * to avoid having everyone that uses
362 * this header file include sys/fs/ufs_inode.h.
363 */
364 void bwrite_common(void *ufsvfsp, struct buf *, int force_wait,
365 int do_relse, int clear_flags);
366 void bwrite(struct buf *);
367 void bwrite2(struct buf *);
368 void bdwrite(struct buf *);
369 void bawrite(struct buf *);
370 void brelse(struct buf *);
371 void iodone(struct buf *);
372 void clrbuf(struct buf *);
373 void bflush(dev_t);
374 void blkflush(dev_t, daddr_t);
375 void binval(dev_t);
376 int bfinval(dev_t, int);
377 void binit(void);
378 void biodone(struct buf *);
379 void bioinit(struct buf *);
380 void biofini(struct buf *);
381 void bp_mapin(struct buf *);
382 void *bp_mapin_common(struct buf *, int);
383 void bp_mapout(struct buf *);
384 int bp_copyin(struct buf *, void *, offset_t, size_t);
385 int bp_copyout(void *, struct buf *, offset_t, size_t);
386 void bp_init(size_t, uint_t);
387 int bp_color(struct buf *);
388 void pageio_done(struct buf *);
389 struct buf *bread(dev_t, daddr_t, long);
390 struct buf *bread_common(void *, dev_t, daddr_t, long);
391 struct buf *breada(dev_t, daddr_t, daddr_t, long);
392 struct buf *getblk(dev_t, daddr_t, long);
393 struct buf *getblk_common(void *, dev_t, daddr_t, long, int);
394 struct buf *ngeteblk(long);
395 struct buf *geteblk(void);
396 struct buf *pageio_setup(struct page *, size_t, struct vnode *, int);
397 void bioerror(struct buf *bp, int error);
398 void bioreset(struct buf *bp);
399 struct buf *bioclone(struct buf *, off_t, size_t, dev_t, daddr_t,
400 int (*)(struct buf *), struct buf *, int);
401 size_t biosize(void);
402 #endif /* defined(_KERNEL) || defined(_FAKE_KERNEL) */
403
404 #ifdef __cplusplus
405 }
406 #endif
407
408 #endif /* _SYS_BUF_H */