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 /* does not contain valid info */ 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 * Insq/Remq for the buffer hash lists. 192 */ 193 #define bremhash(bp) { \ 194 ASSERT((bp)->b_forw != NULL); \ 195 ASSERT((bp)->b_back != NULL); \ 196 (bp)->b_back->b_forw = (bp)->b_forw; \ 197 (bp)->b_forw->b_back = (bp)->b_back; \ 198 (bp)->b_forw = (bp)->b_back = NULL; \ 199 } 200 #define binshash(bp, dp) { \ 201 ASSERT((bp)->b_forw == NULL); \ 202 ASSERT((bp)->b_back == NULL); \ 203 ASSERT((dp)->b_forw != NULL); \ 204 ASSERT((dp)->b_back != NULL); \ 205 (bp)->b_forw = (dp)->b_forw; \ 206 (bp)->b_back = (dp); \ 207 (dp)->b_forw->b_back = (bp); \ 208 (dp)->b_forw = (bp); \ 209 } 210 211 212 /* 213 * The hash structure maintains two lists: 214 * 215 * 1) The hash list of buffers (b_forw & b_back) 216 * 2) The LRU free list of buffers on this hash bucket (av_forw & av_back) 217 * 218 * The dwbuf structure keeps a list of delayed write buffers per hash bucket 219 * hence there are exactly the same number of dwbuf structures as there are 220 * the hash buckets (hbuf structures) in the system. 221 * 222 * The number of buffers on the freelist may not be equal to the number of 223 * buffers on the hash list. That is because when buffers are busy they are 224 * taken off the freelist but not off the hash list. "b_length" field keeps 225 * track of the number of free buffers (including delayed writes ones) on 226 * the hash bucket. The "b_lock" mutex protects the free list as well as 227 * the hash list. It also protects the counter "b_length". 228 * 229 * Enties b_forw, b_back, av_forw & av_back must be at the same offset 230 * as the ones in buf structure. 231 */ 232 struct hbuf { 233 int b_flags; 234 235 struct buf *b_forw; /* hash list forw pointer */ 236 struct buf *b_back; /* hash list back pointer */ 237 238 struct buf *av_forw; /* free list forw pointer */ 239 struct buf *av_back; /* free list back pointer */ 240 241 int b_length; /* # of entries on free list */ 242 kmutex_t b_lock; /* lock to protect this structure */ 243 }; 244 245 246 /* 247 * The delayed list pointer entries should match with the buf strcuture. 248 */ 249 struct dwbuf { 250 int b_flags; /* not used */ 251 252 struct buf *b_forw; /* not used */ 253 struct buf *b_back; /* not used */ 254 255 struct buf *av_forw; /* delayed write forw pointer */ 256 struct buf *av_back; /* delayed write back pointer */ 257 }; 258 259 260 /* 261 * Unlink a buffer from the available (free or delayed write) list and mark 262 * it busy (internal interface). 263 */ 264 #define notavail(bp) \ 265 {\ 266 ASSERT(SEMA_HELD(&bp->b_sem)); \ 267 ASSERT((bp)->av_forw != NULL); \ 268 ASSERT((bp)->av_back != NULL); \ 269 ASSERT((bp)->av_forw != (bp)); \ 270 ASSERT((bp)->av_back != (bp)); \ 271 (bp)->av_back->av_forw = (bp)->av_forw; \ 272 (bp)->av_forw->av_back = (bp)->av_back; \ 273 (bp)->b_flags |= B_BUSY; \ 274 (bp)->av_forw = (bp)->av_back = NULL; \ 275 } 276 277 #if defined(_KERNEL) 278 /* 279 * Macros to avoid the extra function call needed for binary compat. 280 * 281 * B_RETRYWRI is not included in clear_flags for BWRITE(), BWRITE2(), 282 * or brwrite() so that the retry operation is persistent until the 283 * write either succeeds or the buffer is bfinval()'d. 284 * 285 */ 286 #define BREAD(dev, blkno, bsize) \ 287 bread_common(/* ufsvfsp */ NULL, dev, blkno, bsize) 288 289 #define BWRITE(bp) \ 290 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 0, \ 291 /* do_relse */ 1, \ 292 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)) 293 294 #define BWRITE2(bp) \ 295 bwrite_common(/* ufsvfsp */ NULL, bp, /* force_wait */ 1, \ 296 /* do_relse */ 0, \ 297 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)) 298 299 #define GETBLK(dev, blkno, bsize) \ 300 getblk_common(/* ufsvfsp */ NULL, dev, blkno, bsize, /* errflg */ 0) 301 302 303 /* 304 * Macros for new retry write interfaces. 305 */ 306 307 /* 308 * Same as bdwrite() except write failures are retried. 309 */ 310 #define bdrwrite(bp) { \ 311 (bp)->b_flags |= B_RETRYWRI; \ 312 bdwrite((bp)); \ 313 } 314 315 /* 316 * Same as bwrite() except write failures are retried. 317 */ 318 #define brwrite(bp) { \ 319 (bp)->b_flags |= B_RETRYWRI; \ 320 bwrite_common((bp), /* force_wait */ 0, /* do_relse */ 1, \ 321 /* clear_flags */ (B_READ | B_DONE | B_ERROR | B_DELWRI)); \ 322 } 323 324 extern struct hbuf *hbuf; /* Hash table */ 325 extern struct dwbuf *dwbuf; /* delayed write hash table */ 326 extern struct buf *buf; /* The buffer pool itself */ 327 extern struct buf bfreelist; /* head of available list */ 328 329 extern void (*bio_lufs_strategy)(void *, buf_t *); /* UFS Logging */ 330 extern void (*bio_snapshot_strategy)(void *, buf_t *); /* UFS snapshots */ 331 332 int bcheck(dev_t, struct buf *); 333 int iowait(struct buf *); 334 int hash2ints(int x, int y); 335 int bio_busy(int); 336 int biowait(struct buf *); 337 int biomodified(struct buf *); 338 int geterror(struct buf *); 339 void minphys(struct buf *); 340 /* 341 * ufsvfsp is declared as a void * to avoid having everyone that uses 342 * this header file include sys/fs/ufs_inode.h. 343 */ 344 void bwrite_common(void *ufsvfsp, struct buf *, int force_wait, 345 int do_relse, int clear_flags); 346 void bwrite(struct buf *); 347 void bwrite2(struct buf *); 348 void bdwrite(struct buf *); 349 void bawrite(struct buf *); 350 void brelse(struct buf *); 351 void iodone(struct buf *); 352 void clrbuf(struct buf *); 353 void bflush(dev_t); 354 void blkflush(dev_t, daddr_t); 355 void binval(dev_t); 356 int bfinval(dev_t, int); 357 void binit(void); 358 void biodone(struct buf *); 359 void bioinit(struct buf *); 360 void biofini(struct buf *); 361 void bp_mapin(struct buf *); 362 void *bp_mapin_common(struct buf *, int); 363 void bp_mapout(struct buf *); 364 int bp_copyin(struct buf *, void *, offset_t, size_t); 365 int bp_copyout(void *, struct buf *, offset_t, size_t); 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