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, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2005 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 28 /* All Rights Reserved */ 29 30 /* 31 * University Copyright- Copyright (c) 1982, 1986, 1988 32 * The Regents of the University of California 33 * All Rights Reserved 34 * 35 * University Acknowledgment- Portions of this document are derived from 36 * software developed by the University of California, Berkeley, and its 37 * contributors. 38 */ 39 40 #ifndef _SYS_BUF_H 41 #define _SYS_BUF_H 42 43 #pragma ident "%Z%%M% %I% %E% SMI" 44 45 #include <sys/types32.h> 46 #include <sys/t_lock.h> 47 #include <sys/kstat.h> 48 49 #ifdef __cplusplus 50 extern "C" { 51 #endif 52 53 /* 54 * Each buffer in the pool is usually doubly linked into 2 lists: 55 * the device with which it is currently associated (always) 56 * and also on a list of blocks available for allocation 57 * for other use (usually). 58 * The latter list is kept in last-used order, and the two 59 * lists are doubly linked to make it easy to remove 60 * a buffer from one list when it was found by 61 * looking through the other. 62 * A buffer is on the available list, and is liable 63 * to be reassigned to another disk block, if and only 64 * if it is not marked BUSY. When a buffer is busy, the 65 * available-list pointers can be used for other purposes. 66 * Most drivers use the forward ptr as a link in their I/O active queue. 67 * A buffer header contains all the information required to perform I/O. 68 * Most of the routines which manipulate these things are in bio.c. 69 * 70 * There are a number of locks associated with the buffer management 71 * system. 72 * hbuf.b_lock: protects hash chains, buffer hdr freelists 73 * and delayed write freelist 74 * bfree_lock; protects the bfreelist structure 75 * bhdr_lock: protects the free header list 76 * blist_lock: protects b_list fields 77 * buf.b_sem: protects all remaining members in the buf struct 78 * buf.b_io: I/O synchronization variable 79 * 80 * A buffer header is never "locked" (b_sem) when it is on 81 * a "freelist" (bhdrlist or bfreelist avail lists). 82 */ 83 typedef struct buf { 84 int b_flags; /* see defines below */ 85 struct buf *b_forw; /* headed by d_tab of conf.c */ 86 struct buf *b_back; /* " */ 87 struct buf *av_forw; /* position on free list, */ 88 struct buf *av_back; /* if not BUSY */ 89 o_dev_t b_dev; /* OLD major+minor device name */ 90 size_t b_bcount; /* transfer count */ 91 union { 92 caddr_t b_addr; /* low order core address */ 93 struct fs *b_fs; /* superblocks */ 94 struct cg *b_cg; /* UFS cylinder group block */ 95 struct dinode *b_dino; /* UFS ilist */ 96 daddr32_t *b_daddr; /* disk blocks */ 97 } b_un; 98 99 lldaddr_t _b_blkno; /* block # on device (union) */ 100 #define b_lblkno _b_blkno._f 101 #ifdef _LP64 102 #define b_blkno _b_blkno._f 103 #else 104 #define b_blkno _b_blkno._p._l 105 #endif /* _LP64 */ 106 107 char b_obs1; /* obsolete */ 108 size_t b_resid; /* words not transferred after error */ 109 clock_t b_start; /* request start time */ 110 struct proc *b_proc; /* process doing physical or swap I/O */ 111 struct page *b_pages; /* page list for PAGEIO */ 112 clock_t b_obs2; /* obsolete */ 113 /* Begin new stuff */ 114 #define b_actf av_forw 115 #define b_actl av_back 116 #define b_active b_bcount 117 #define b_errcnt b_resid 118 size_t b_bufsize; /* size of allocated buffer */ 119 int (*b_iodone)(struct buf *); /* function called by iodone */ 120 struct vnode *b_vp; /* vnode associated with block */ 121 struct buf *b_chain; /* chain together all buffers here */ 122 int b_obs3; /* obsolete */ 123 int b_error; /* expanded error field */ 124 void *b_private; /* "opaque" driver private area */ 125 dev_t b_edev; /* expanded dev field */ 126 ksema_t b_sem; /* Exclusive access to buf */ 127 ksema_t b_io; /* I/O Synchronization */ 128 struct buf *b_list; /* List of potential B_DELWRI bufs */ 129 struct page **b_shadow; /* shadow page list */ 130 void *b_dip; /* device info pointer */ 131 struct vnode *b_file; /* file associated with this buffer */ 132 offset_t b_offset; /* offset in file assoc. with buffer */ 133 } buf_t; 134 135 /* 136 * Bufhd structures used at the head of the hashed buffer queues. 137 * We only need seven words for this, so this abbreviated 138 * definition saves some space. 139 */ 140 struct diskhd { 141 int b_flags; /* not used, needed for consistency */ 142 struct buf *b_forw, *b_back; /* queue of unit queues */ 143 struct buf *av_forw, *av_back; /* queue of bufs for this unit */ 144 o_dev_t b_dev; /* OLD major+minor device name */ 145 size_t b_bcount; /* transfer count */ 146 }; 147 148 149 /* 150 * Statistics on the buffer cache 151 */ 152 struct biostats { 153 kstat_named_t bio_lookup; /* requests to assign buffer */ 154 kstat_named_t bio_hit; /* buffer already associated with blk */ 155 kstat_named_t bio_bufwant; /* kmem_allocs NOSLEEP failed new buf */ 156 kstat_named_t bio_bufwait; /* kmem_allocs with KM_SLEEP for buf */ 157 kstat_named_t bio_bufbusy; /* buffer locked by someone else */ 158 kstat_named_t bio_bufdup; /* duplicate buffer found for block */ 159 }; 160 161 /* 162 * These flags are kept in b_flags. 163 * The first group is part of the DDI 164 */ 165 #define B_BUSY 0x0001 /* not on av_forw/back list */ 166 #define B_DONE 0x0002 /* transaction finished */ 167 #define B_ERROR 0x0004 /* transaction aborted */ 168 #define B_PAGEIO 0x0010 /* do I/O to pages on bp->p_pages */ 169 #define B_PHYS 0x0020 /* Physical IO potentially using UNIBUS map */ 170 #define B_READ 0x0040 /* read when I/O occurs */ 171 #define B_WRITE 0x0100 /* non-read pseudo-flag */ 172 173 /* Not part of the DDI */ 174 #define B_WANTED 0x0080 /* issue wakeup when BUSY goes off */ 175 #define B_AGE 0x000200 /* delayed write for correct aging */ 176 #define B_ASYNC 0x000400 /* don't wait for I/O completion */ 177 #define B_DELWRI 0x000800 /* delayed write-wait til buf needed */ 178 #define B_STALE 0x001000 /* on av_* list; invalid contents */ 179 #define B_DONTNEED 0x002000 /* after write, need not be cached */ 180 #define B_REMAPPED 0x004000 /* buffer is kernel addressable */ 181 #define B_FREE 0x008000 /* free page when done */ 182 #define B_INVAL 0x010000 /* does not contain valid info */ 183 #define B_FORCE 0x020000 /* semi-permanent removal from cache */ 184 #define B_NOCACHE 0x080000 /* don't cache block when released */ 185 #define B_TRUNC 0x100000 /* truncate page without I/O */ 186 #define B_SHADOW 0x200000 /* is b_shadow field valid? */ 187 #define B_RETRYWRI 0x400000 /* retry write til works or bfinval */ 188 #define B_FAILFAST 0x1000000 /* Fail promptly if device goes away */ 189 #define B_STARTED 0x2000000 /* io:::start probe called for buf */ 190 #define B_ABRWRITE 0x4000000 /* Application based recovery active */ 191 192 /* 193 * Insq/Remq for the buffer hash lists. 194 */ 195 #define bremhash(bp) { \ 196 ASSERT((bp)->b_forw != NULL); \ 197 ASSERT((bp)->b_back != NULL); \ 198 (bp)->b_back->b_forw = (bp)->b_forw; \ 199 (bp)->b_forw->b_back = (bp)->b_back; \ 200 (bp)->b_forw = (bp)->b_back = NULL; \ 201 } 202 #define binshash(bp, dp) { \ 203 ASSERT((bp)->b_forw == NULL); \ 204 ASSERT((bp)->b_back == NULL); \ 205 ASSERT((dp)->b_forw != NULL); \ 206 ASSERT((dp)->b_back != NULL); \ 207 (bp)->b_forw = (dp)->b_forw; \ 208 (bp)->b_back = (dp); \ 209 (dp)->b_forw->b_back = (bp); \ 210 (dp)->b_forw = (bp); \ 211 } 212 213 214 /* 215 * The hash structure maintains two lists: 216 * 217 * 1) The hash list of buffers (b_forw & b_back) 218 * 2) The LRU free list of buffers on this hash bucket (av_forw & av_back) 219 * 220 * The dwbuf structure keeps a list of delayed write buffers per hash bucket 221 * hence there are exactly the same number of dwbuf structures as there are 222 * the hash buckets (hbuf structures) in the system. 223 * 224 * The number of buffers on the freelist may not be equal to the number of 225 * buffers on the hash list. That is because when buffers are busy they are 226 * taken off the freelist but not off the hash list. "b_length" field keeps 227 * track of the number of free buffers (including delayed writes ones) on 228 * the hash bucket. The "b_lock" mutex protects the free list as well as 229 * the hash list. It also protects the counter "b_length". 230 * 231 * Enties b_forw, b_back, av_forw & av_back must be at the same offset 232 * as the ones in buf structure. 233 */ 234 struct hbuf { 235 int b_flags; 236 237 struct buf *b_forw; /* hash list forw pointer */ 238 struct buf *b_back; /* hash list back pointer */ 239 240 struct buf *av_forw; /* free list forw pointer */ 241 struct buf *av_back; /* free list back pointer */ 242 243 int b_length; /* # of entries on free list */ 244 kmutex_t b_lock; /* lock to protect this structure */ 245 }; 246 247 248 /* 249 * The delayed list pointer entries should match with the buf strcuture. 250 */ 251 struct dwbuf { 252 int b_flags; /* not used */ 253 254 struct buf *b_forw; /* not used */ 255 struct buf *b_back; /* not used */ 256 257 struct buf *av_forw; /* delayed write forw pointer */ 258 struct buf *av_back; /* delayed write back pointer */ 259 }; 260 261 262 /* 263 * Unlink a buffer from the available (free or delayed write) list and mark 264 * it busy (internal interface). 265 */ 266 #define notavail(bp) \ 267 {\ 268 ASSERT(SEMA_HELD(&bp->b_sem)); \ 269 ASSERT((bp)->av_forw != NULL); \ 270 ASSERT((bp)->av_back != NULL); \ 271 ASSERT((bp)->av_forw != (bp)); \ 272 ASSERT((bp)->av_back != (bp)); \ 273 (bp)->av_back->av_forw = (bp)->av_forw; \ 274 (bp)->av_forw->av_back = (bp)->av_back; \ 275 (bp)->b_flags |= B_BUSY; \ 276 (bp)->av_forw = (bp)->av_back = NULL; \ 277 } 278 279 #if defined(_KERNEL) 280 /* 281 * Macros to avoid the extra function call needed for binary compat. 282 * 283 * B_RETRYWRI is not included in clear_flags for BWRITE(), BWRITE2(), 284 * or brwrite() so that the retry operation is persistent until the 285 * write either succeeds or the buffer is bfinval()'d. 286 * 287 */ 288 #define BREAD(dev, blkno, bsize) \ 289 bread_common(/* ufsvfsp */ NULL, dev, blkno, bsize) 290 291 #define BWRITE(bp) \ 292 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 0, \ 293 /* do_relse */ 1, \ 294 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)) 295 296 #define BWRITE2(bp) \ 297 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 1, \ 298 /* do_relse */ 0, \ 299 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)) 300 301 #define GETBLK(dev, blkno, bsize) \ 302 getblk_common(/* ufsvfsp */ NULL, dev, blkno, bsize, /* errflg */ 0) 303 304 305 /* 306 * Macros for new retry write interfaces. 307 */ 308 309 /* 310 * Same as bdwrite() except write failures are retried. 311 */ 312 #define bdrwrite(bp) { \ 313 (bp)->b_flags |= B_RETRYWRI; \ 314 bdwrite((bp)); \ 315 } 316 317 /* 318 * Same as bwrite() except write failures are retried. 319 */ 320 #define brwrite(bp) { \ 321 (bp)->b_flags |= B_RETRYWRI; \ 322 bwrite_common((bp), /* force_wait */ 0, /* do_relse */ 1, \ 323 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)); \ 324 } 325 326 extern struct hbuf *hbuf; /* Hash table */ 327 extern struct dwbuf *dwbuf; /* delayed write hash table */ 328 extern struct buf *buf; /* The buffer pool itself */ 329 extern struct buf bfreelist; /* head of available list */ 330 331 extern void (*bio_lufs_strategy)(void *, buf_t *); /* UFS Logging */ 332 extern void (*bio_snapshot_strategy)(void *, buf_t *); /* UFS snapshots */ 333 334 int bcheck(dev_t, struct buf *); 335 int iowait(struct buf *); 336 int hash2ints(int x, int y); 337 int bio_busy(int); 338 int biowait(struct buf *); 339 int biomodified(struct buf *); 340 int geterror(struct buf *); 341 void minphys(struct buf *); 342 /* 343 * ufsvfsp is declared as a void * to avoid having everyone that uses 344 * this header file include sys/fs/ufs_inode.h. 345 */ 346 void bwrite_common(void *ufsvfsp, struct buf *, int force_wait, 347 int do_relse, int clear_flags); 348 void bwrite(struct buf *); 349 void bwrite2(struct buf *); 350 void bdwrite(struct buf *); 351 void bawrite(struct buf *); 352 void brelse(struct buf *); 353 void iodone(struct buf *); 354 void clrbuf(struct buf *); 355 void bflush(dev_t); 356 void blkflush(dev_t, daddr_t); 357 void binval(dev_t); 358 int bfinval(dev_t, int); 359 void binit(void); 360 void biodone(struct buf *); 361 void bioinit(struct buf *); 362 void biofini(struct buf *); 363 void bp_mapin(struct buf *); 364 void *bp_mapin_common(struct buf *, int); 365 void bp_mapout(struct buf *); 366 void bp_init(size_t, uint_t); 367 int bp_color(struct buf *); 368 void pageio_done(struct buf *); 369 struct buf *bread(dev_t, daddr_t, long); 370 struct buf *bread_common(void *, dev_t, daddr_t, long); 371 struct buf *breada(dev_t, daddr_t, daddr_t, long); 372 struct buf *getblk(dev_t, daddr_t, long); 373 struct buf *getblk_common(void *, dev_t, daddr_t, long, int); 374 struct buf *ngeteblk(long); 375 struct buf *geteblk(void); 376 struct buf *pageio_setup(struct page *, size_t, struct vnode *, int); 377 void bioerror(struct buf *bp, int error); 378 void bioreset(struct buf *bp); 379 struct buf *bioclone(struct buf *, off_t, size_t, dev_t, daddr_t, 380 int (*)(struct buf *), struct buf *, int); 381 size_t biosize(void); 382 #endif /* defined(_KERNEL) */ 383 384 #ifdef __cplusplus 385 } 386 #endif 387 388 #endif /* _SYS_BUF_H */ 389