1 /* 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)buf.h 8.9 (Berkeley) 3/30/95 39 * $FreeBSD: src/sys/sys/buf.h,v 1.88.2.10 2003/01/25 19:02:23 dillon Exp $ 40 * $DragonFly: src/sys/sys/buf.h,v 1.54 2008/08/29 20:08:37 dillon Exp $ 41 */ 42 43 #ifndef _SYS_BUF_H_ 44 #define _SYS_BUF_H_ 45 46 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) 47 48 #ifndef _SYS_QUEUE_H_ 49 #include <sys/queue.h> 50 #endif 51 #ifndef _SYS_LOCK_H_ 52 #include <sys/lock.h> 53 #endif 54 #ifndef _SYS_DEVICE_H_ 55 #include <sys/device.h> 56 #endif 57 58 #ifndef _SYS_XIO_H_ 59 #include <sys/xio.h> 60 #endif 61 #ifndef _SYS_TREE_H_ 62 #include <sys/tree.h> 63 #endif 64 #ifndef _SYS_BIO_H_ 65 #include <sys/bio.h> 66 #endif 67 #ifndef _SYS_SPINLOCK_H_ 68 #include <sys/spinlock.h> 69 #endif 70 71 struct buf; 72 struct bio; 73 struct mount; 74 struct vnode; 75 struct xio; 76 77 #define NBUF_BIO 6 78 79 struct buf_rb_tree; 80 struct buf_rb_hash; 81 RB_PROTOTYPE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, off_t); 82 RB_PROTOTYPE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, off_t); 83 84 /* 85 * To avoid including <ufs/ffs/softdep.h> 86 */ 87 LIST_HEAD(workhead, worklist); 88 89 #endif 90 91 typedef enum buf_cmd { 92 BUF_CMD_DONE = 0, 93 BUF_CMD_READ, 94 BUF_CMD_WRITE, 95 BUF_CMD_FREEBLKS, 96 BUF_CMD_FORMAT, 97 BUF_CMD_FLUSH 98 } buf_cmd_t; 99 100 #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) 101 102 /* 103 * The buffer header describes an I/O operation in the kernel. 104 * 105 * NOTES: 106 * b_bufsize represents the filesystem block size (for this particular 107 * block) and/or the allocation size or original request size. This 108 * field is NOT USED by lower device layers. VNode and device 109 * strategy routines WILL NEVER ACCESS THIS FIELD. 110 * 111 * b_bcount represents the I/O request size. Unless B_NOBCLIP is set, 112 * the device chain is allowed to clip b_bcount to accomodate the device 113 * EOF. Note that this is different from the byte oriented file EOF. 114 * If B_NOBCLIP is set, the device chain is required to generate an 115 * error if it would othrewise have to clip the request. Buffers 116 * obtained via getblk() automatically set B_NOBCLIP. It is important 117 * to note that EOF clipping via b_bcount is different from EOF clipping 118 * via returning a b_actual < b_bcount. B_NOBCLIP only effects block 119 * oriented EOF clipping (b_bcount modifications). 120 * 121 * b_actual represents the number of bytes of I/O that actually occured, 122 * whether an error occured or not. b_actual must be initialized to 0 123 * prior to initiating I/O as the device drivers will assume it to 124 * start at 0. 125 * 126 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned 127 * ranges of dirty data that need to be written to backing store. 128 * The range is typically clipped at b_bcount (not b_bufsize). 129 * 130 * b_bio1 and b_bio2 represent the two primary I/O layers. Additional 131 * I/O layers are allocated out of the object cache and may also exist. 132 * 133 * b_bio1 is the logical layer and contains offset or block number 134 * data for the primary vnode, b_vp. I/O operations are almost 135 * universally initiated from the logical layer, so you will often 136 * see things like: vn_strategy(bp->b_vp, &bp->b_bio1). 137 * 138 * b_bio2 is the first physical layer (typically the slice-relative 139 * layer) and contains the translated offset or block number for 140 * the block device underlying a filesystem. Filesystems such as UFS 141 * will maintain cached translations and you may see them initiate 142 * a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2). BUT, 143 * remember that the layering is relative to bp->b_vp, so the 144 * device-relative block numbers for buffer cache operations that occur 145 * directly on a block device will be in the first BIO layer. 146 * 147 * b_ops - initialized if a buffer has a bio_ops 148 * 149 * NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly. 150 * ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO 151 * PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE 152 * I/O DEEPER. In particular, a vn_strategy() or dev_dstrategy() 153 * call should not ever access buf->b_vp as this vnode may be totally 154 * unrelated to the vnode/device whos strategy routine was called. 155 */ 156 struct buf { 157 RB_ENTRY(buf) b_rbnode; /* RB node in vnode clean/dirty tree */ 158 RB_ENTRY(buf) b_rbhash; /* RB node in vnode hash tree */ 159 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */ 160 struct buf *b_cluster_next; /* Next buffer (cluster code) */ 161 struct vnode *b_vp; /* (vp, loffset) index */ 162 struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */ 163 u_int32_t b_flags; /* B_* flags. */ 164 unsigned short b_qindex; /* buffer queue index */ 165 unsigned char b_act_count; /* similar to vm_page act_count */ 166 unsigned char b_unused01; 167 struct lock b_lock; /* Buffer lock */ 168 void *b_iosched; /* I/O scheduler priv data */ 169 buf_cmd_t b_cmd; /* I/O command */ 170 int b_bufsize; /* Allocated buffer size. */ 171 int b_runningbufspace; /* when I/O is running, pipelining */ 172 int b_bcount; /* Valid bytes in buffer. */ 173 int b_resid; /* Remaining I/O */ 174 int b_error; /* Error return */ 175 caddr_t b_data; /* Memory, superblocks, indirect etc. */ 176 caddr_t b_kvabase; /* base kva for buffer */ 177 int b_kvasize; /* size of kva for buffer */ 178 int b_dirtyoff; /* Offset in buffer of dirty region. */ 179 int b_dirtyend; /* Offset of end of dirty region. */ 180 int b_refs; /* FINDBLK_REF / unrefblk() */ 181 struct xio b_xio; /* data buffer page list management */ 182 struct bio_ops *b_ops; /* bio_ops used w/ b_dep */ 183 struct workhead b_dep; /* List of filesystem dependencies. */ 184 }; 185 186 /* 187 * XXX temporary 188 */ 189 #define b_bio1 b_bio_array[0] /* logical layer */ 190 #define b_bio2 b_bio_array[1] /* (typically) the disk layer */ 191 #define b_loffset b_bio1.bio_offset 192 193 194 /* 195 * Flags passed to getblk() 196 * 197 * GETBLK_PCATCH - Allow signals to be caught. getblk() is allowed to return 198 * NULL if this flag is passed. 199 * 200 * GETBLK_BHEAVY - This is a heavy weight buffer, meaning that resolving 201 * writes can require additional buffers. 202 * 203 * GETBLK_SZMATCH- blksize must match pre-existing b_bcount. getblk() can 204 * return NULL. 205 * 206 * GETBLK_NOWAIT - Do not use a blocking lock. getblk() can return NULL. 207 */ 208 #define GETBLK_PCATCH 0x0001 /* catch signals */ 209 #define GETBLK_BHEAVY 0x0002 /* heavy weight buffer */ 210 #define GETBLK_SZMATCH 0x0004 /* pre-existing buffer must match */ 211 #define GETBLK_NOWAIT 0x0008 /* non-blocking */ 212 213 #define FINDBLK_TEST 0x0010 /* test only, do not lock */ 214 #define FINDBLK_NBLOCK 0x0020 /* use non-blocking lock, can return NULL */ 215 #define FINDBLK_REF 0x0040 /* ref the buf to prevent reuse */ 216 217 /* 218 * These flags are kept in b_flags. 219 * 220 * Notes: 221 * 222 * B_PAGING Indicates that bp is being used by the paging system or 223 * some paging system and that the bp is not linked into 224 * the b_vp's clean/dirty linked lists or ref counts. 225 * Buffer vp reassignments are illegal in this case. 226 * 227 * B_CACHE This may only be set if the buffer is entirely valid. 228 * The situation where B_DELWRI is set and B_CACHE is 229 * clear MUST be committed to disk by getblk() so 230 * B_DELWRI can also be cleared. See the comments for 231 * getblk() in kern/vfs_bio.c. If B_CACHE is clear, 232 * the caller is expected to clear B_ERROR|B_INVAL, 233 * set BUF_CMD_READ, and initiate an I/O. 234 * 235 * The 'entire buffer' is defined to be the range from 236 * 0 through b_bcount. 237 * 238 * B_MALLOC Request that the buffer be allocated from the malloc 239 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned. 240 * 241 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers 242 * by filesystems that allow clustering when the buffer 243 * is fully dirty and indicates that it may be clustered 244 * with other adjacent dirty buffers. Note the clustering 245 * may not be used with the stage 1 data write under NFS 246 * but may be used for the commit rpc portion. 247 * 248 * B_VMIO Indicates that the buffer is tied into an VM object. 249 * The buffer's data is always PAGE_SIZE aligned even 250 * if b_bufsize and b_bcount are not. ( b_bufsize is 251 * always at least DEV_BSIZE aligned, though ). 252 * 253 * B_DIRECT Hint that we should attempt to completely free 254 * the pages underlying the buffer. B_DIRECT is 255 * sticky until the buffer is released and typically 256 * only has an effect when B_RELBUF is also set. 257 * 258 * B_LOCKED The buffer will be released to the locked queue 259 * regardless of its current state. Note that 260 * if B_DELWRI is set, no I/O occurs until the caller 261 * acquires the buffer, clears B_LOCKED, then releases 262 * it again. 263 * 264 * B_AGE When allocating a new buffer any buffer encountered 265 * with B_AGE set will be reallocated more quickly then 266 * buffers encountered without it set. B_AGE is set 267 * as part of the loop so idle buffers should eventually 268 * wind up with B_AGE set. B_AGE explicitly does NOT 269 * cause the buffer to be instantly reallocated for 270 * other purposes. 271 * 272 * Standard buffer flushing routines leave B_AGE intact 273 * through the DIRTY queue and into the CLEAN queue. 274 * Setting B_AGE on a dirty buffer will not cause it 275 * to be flushed more quickly but will cause it to be 276 * reallocated more quickly after having been flushed. 277 * 278 * B_NOCACHE Request that the buffer and backing store be 279 * destroyed on completion. If B_DELWRI is set and the 280 * write fails, the buffer remains intact. 281 * 282 * B_NOTMETA May be set on block device buffers representing 283 * file data (i.e. which aren't really meta-data), 284 * which will cause the buffer cache to set PG_NOTMETA 285 * in the VM pages when releasing them and the 286 * swapcache to not try to cache them. 287 */ 288 289 #define B_AGE 0x00000001 /* Reuse more quickly */ 290 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */ 291 #define B_NOTMETA 0x00000004 /* This really isn't metadata */ 292 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */ 293 #define B_DEFERRED 0x00000010 /* vfs-controlled deferment */ 294 #define B_CACHE 0x00000020 /* Bread found us in the cache. */ 295 #define B_HASHED 0x00000040 /* Indexed via v_rbhash_tree */ 296 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */ 297 #define B_BNOCLIP 0x00000100 /* EOF clipping b_bcount not allowed */ 298 #define B_HASBOGUS 0x00000200 /* Contains bogus pages */ 299 #define B_EINTR 0x00000400 /* I/O was interrupted */ 300 #define B_ERROR 0x00000800 /* I/O error occurred. */ 301 #define B_IODEBUG 0x00001000 /* (Debugging only bread) */ 302 #define B_INVAL 0x00002000 /* Does not contain valid info. */ 303 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */ 304 #define B_NOCACHE 0x00008000 /* Destroy buffer AND backing store */ 305 #define B_MALLOC 0x00010000 /* malloced b_data */ 306 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */ 307 #define B_UNUSED18 0x00040000 308 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */ 309 #define B_HEAVY 0x00100000 /* Heavy-weight buffer */ 310 #define B_DIRTY 0x00200000 /* Needs writing later. */ 311 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */ 312 #define B_UNUSED23 0x00800000 /* Request wakeup on done */ 313 #define B_VNCLEAN 0x01000000 /* On vnode clean list */ 314 #define B_VNDIRTY 0x02000000 /* On vnode dirty list */ 315 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */ 316 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */ 317 #define B_RAM 0x10000000 /* Read ahead mark (flag) */ 318 #define B_VMIO 0x20000000 /* VMIO flag */ 319 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */ 320 #define B_VFSFLAG1 0x80000000 /* VFSs can set this flag */ 321 322 #define PRINT_BUF_FLAGS "\20" \ 323 "\40unused31\37cluster\36vmio\35ram\34ordered" \ 324 "\33paging\32vndirty\31vnclean\30unused23\27relbuf\26dirty" \ 325 "\25unused20\24raw\23unused18\22clusterok\21malloc\20nocache" \ 326 "\17locked\16inval\15unused12\14error\13eintr\12unused9\11bnoclip" \ 327 "\10delwri\7hashed\6cache\5deferred\4direct\3unused2\2needcommit\1age" 328 329 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */ 330 331 #ifdef _KERNEL 332 /* 333 * Buffer locking. See sys/buf2.h for inline functions. 334 */ 335 extern char *buf_wmesg; /* Default buffer lock message */ 336 #define BUF_WMESG "bufwait" 337 338 #endif /* _KERNEL */ 339 340 struct bio_queue_head { 341 TAILQ_HEAD(bio_queue, bio) queue; 342 off_t off_unused; 343 int reorder; 344 struct bio *transition; 345 struct bio *bio_unused; 346 }; 347 348 /* 349 * This structure describes a clustered I/O. 350 */ 351 struct cluster_save { 352 int bs_nchildren; /* Number of associated buffers. */ 353 struct buf **bs_children; /* List of associated buffers. */ 354 }; 355 356 /* 357 * Zero out the buffer's data area. 358 */ 359 #define clrbuf(bp) { \ 360 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \ 361 (bp)->b_resid = 0; \ 362 } 363 364 /* 365 * Flags to low-level bitmap allocation routines (balloc). 366 * 367 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count 368 * to 127. 369 */ 370 #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */ 371 #define B_SEQSHIFT 24 /* Sequential heuristic shift. */ 372 #define B_SEQMAX 0x7F 373 #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */ 374 #define B_SYNC 0x02 /* Do all allocations synchronously. */ 375 376 #ifdef _KERNEL 377 extern int nbuf; /* The number of buffer headers */ 378 extern long maxswzone; /* Max KVA for swap structures */ 379 extern long maxbcache; /* Max KVA for buffer cache */ 380 extern int hidirtybufspace; 381 extern int buf_maxio; /* nominal maximum I/O for buffer */ 382 extern struct buf *buf; /* The buffer headers. */ 383 extern char *buffers; /* The buffer contents. */ 384 extern int bufpages; /* Number of memory pages in the buffer pool. */ 385 extern struct buf *swbuf; /* Swap I/O buffer headers. */ 386 extern int nswbuf; /* Number of swap I/O buffer headers. */ 387 extern int bioq_reorder_burst_interval; 388 extern int bioq_reorder_burst_bytes; 389 extern int bioq_reorder_minor_interval; 390 extern int bioq_reorder_minor_bytes; 391 392 struct uio; 393 394 void bufinit (void); 395 int bd_heatup (void); 396 void bd_wait (int count); 397 void waitrunningbufspace(void); 398 int buf_dirty_count_severe (void); 399 int buf_runningbufspace_severe (void); 400 void initbufbio(struct buf *); 401 void reinitbufbio(struct buf *); 402 void clearbiocache(struct bio *); 403 void bremfree (struct buf *); 404 int bread (struct vnode *, off_t, int, struct buf **); 405 int breadn (struct vnode *, off_t, int, off_t *, int *, int, 406 struct buf **); 407 int bwrite (struct buf *); 408 void bdwrite (struct buf *); 409 void buwrite (struct buf *); 410 void bawrite (struct buf *); 411 void bdirty (struct buf *); 412 void bheavy (struct buf *); 413 void bundirty (struct buf *); 414 int bowrite (struct buf *); 415 void brelse (struct buf *); 416 void bqrelse (struct buf *); 417 int vfs_bio_awrite (struct buf *); 418 struct buf *getpbuf (int *); 419 struct buf *getpbuf_kva (int *); 420 int inmem (struct vnode *, off_t); 421 struct buf *findblk (struct vnode *, off_t, int); 422 struct buf *getblk (struct vnode *, off_t, int, int, int); 423 struct buf *getcacheblk (struct vnode *, off_t); 424 struct buf *geteblk (int); 425 void unrefblk(struct buf *bp); 426 void regetblk(struct buf *bp); 427 struct bio *push_bio(struct bio *); 428 struct bio *pop_bio(struct bio *); 429 int biowait (struct bio *, const char *); 430 int biowait_timeout (struct bio *, const char *, int); 431 void bpdone (struct buf *, int); 432 void biodone (struct bio *); 433 void biodone_sync (struct bio *); 434 435 void cluster_append(struct bio *, struct buf *); 436 int cluster_read (struct vnode *, off_t, off_t, int, 437 size_t, size_t, struct buf **); 438 int cluster_wbuild (struct vnode *, int, off_t, int); 439 void cluster_write (struct buf *, off_t, int, int); 440 int physread (struct dev_read_args *); 441 int physwrite (struct dev_write_args *); 442 void vfs_bio_clrbuf (struct buf *); 443 void vfs_busy_pages (struct vnode *, struct buf *); 444 void vfs_unbusy_pages (struct buf *); 445 int vmapbuf (struct buf *, caddr_t, int); 446 void vunmapbuf (struct buf *); 447 void relpbuf (struct buf *, int *); 448 void brelvp (struct buf *); 449 int bgetvp (struct vnode *, struct buf *, int); 450 void bsetrunningbufspace(struct buf *, int); 451 int allocbuf (struct buf *bp, int size); 452 int scan_all_buffers (int (*)(struct buf *, void *), void *); 453 void reassignbuf (struct buf *); 454 struct buf *trypbuf (int *); 455 struct buf *trypbuf_kva (int *); 456 void bio_ops_sync(struct mount *mp); 457 void vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to); 458 void vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to); 459 void nestiobuf_done(struct bio *mbio, int donebytes, int error); 460 void nestiobuf_init(struct bio *mbio); 461 void nestiobuf_add(struct bio *mbio, struct buf *bp, int off, size_t size); 462 void nestiobuf_start(struct bio *mbio); 463 void nestiobuf_error(struct bio *mbio, int error); 464 #endif /* _KERNEL */ 465 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 466 #endif /* !_SYS_BUF_H_ */ 467