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 int b_qindex; /* buffer queue index */ 165 unsigned int b_qcpu; /* buffer queue cpu */ 166 unsigned char b_act_count; /* similar to vm_page act_count */ 167 unsigned char b_unused01; 168 struct lock b_lock; /* Buffer lock */ 169 void *b_iosched; /* I/O scheduler priv data */ 170 buf_cmd_t b_cmd; /* I/O command */ 171 int b_bufsize; /* Allocated buffer size. */ 172 int b_runningbufspace; /* when I/O is running, pipelining */ 173 int b_bcount; /* Valid bytes in buffer. */ 174 int b_resid; /* Remaining I/O */ 175 int b_error; /* Error return */ 176 caddr_t b_data; /* Memory, superblocks, indirect etc. */ 177 caddr_t b_kvabase; /* base kva for buffer */ 178 int b_kvasize; /* size of kva for buffer */ 179 int b_dirtyoff; /* Offset in buffer of dirty region. */ 180 int b_dirtyend; /* Offset of end of dirty region. */ 181 int b_refs; /* FINDBLK_REF/bqhold()/bqdrop() */ 182 struct xio b_xio; /* data buffer page list management */ 183 struct bio_ops *b_ops; /* bio_ops used w/ b_dep */ 184 struct workhead b_dep; /* List of filesystem dependencies. */ 185 }; 186 187 /* 188 * XXX temporary 189 */ 190 #define b_bio1 b_bio_array[0] /* logical layer */ 191 #define b_bio2 b_bio_array[1] /* (typically) the disk layer */ 192 #define b_loffset b_bio1.bio_offset 193 194 195 /* 196 * Flags passed to getblk() 197 * 198 * GETBLK_PCATCH - Allow signals to be caught. getblk() is allowed to return 199 * NULL if this flag is passed. 200 * 201 * GETBLK_BHEAVY - This is a heavy weight buffer, meaning that resolving 202 * writes can require additional buffers. 203 * 204 * GETBLK_SZMATCH- blksize must match pre-existing b_bcount. getblk() can 205 * return NULL. 206 * 207 * GETBLK_NOWAIT - Do not use a blocking lock. getblk() can return NULL. 208 */ 209 #define GETBLK_PCATCH 0x0001 /* catch signals */ 210 #define GETBLK_BHEAVY 0x0002 /* heavy weight buffer */ 211 #define GETBLK_SZMATCH 0x0004 /* pre-existing buffer must match */ 212 #define GETBLK_NOWAIT 0x0008 /* non-blocking */ 213 214 #define FINDBLK_TEST 0x0010 /* test only, do not lock */ 215 #define FINDBLK_NBLOCK 0x0020 /* use non-blocking lock, can return NULL */ 216 #define FINDBLK_REF 0x0040 /* ref the buf to prevent reuse */ 217 218 /* 219 * These flags are kept in b_flags. 220 * 221 * Notes: 222 * 223 * B_PAGING Indicates that bp is being used by the paging system or 224 * some paging system and that the bp is not linked into 225 * the b_vp's clean/dirty linked lists or ref counts. 226 * Buffer vp reassignments are illegal in this case. 227 * 228 * B_CACHE This may only be set if the buffer is entirely valid. 229 * The situation where B_DELWRI is set and B_CACHE is 230 * clear MUST be committed to disk by getblk() so 231 * B_DELWRI can also be cleared. See the comments for 232 * getblk() in kern/vfs_bio.c. If B_CACHE is clear, 233 * the caller is expected to clear B_ERROR|B_INVAL, 234 * set BUF_CMD_READ, and initiate an I/O. 235 * 236 * The 'entire buffer' is defined to be the range from 237 * 0 through b_bcount. 238 * 239 * B_MALLOC Request that the buffer be allocated from the malloc 240 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned. 241 * 242 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers 243 * by filesystems that allow clustering when the buffer 244 * is fully dirty and indicates that it may be clustered 245 * with other adjacent dirty buffers. Note the clustering 246 * may not be used with the stage 1 data write under NFS 247 * but may be used for the commit rpc portion. 248 * 249 * B_VMIO Indicates that the buffer is tied into an VM object. 250 * The buffer's data is always PAGE_SIZE aligned even 251 * if b_bufsize and b_bcount are not. ( b_bufsize is 252 * always at least DEV_BSIZE aligned, though ). 253 * 254 * B_DIRECT Hint that we should attempt to completely free 255 * the pages underlying the buffer. B_DIRECT is 256 * sticky until the buffer is released and typically 257 * only has an effect when B_RELBUF is also set. 258 * 259 * B_LOCKED The buffer will be released to the locked queue 260 * regardless of its current state. Note that 261 * if B_DELWRI is set, no I/O occurs until the caller 262 * acquires the buffer, clears B_LOCKED, then releases 263 * it again. 264 * 265 * B_AGE When allocating a new buffer any buffer encountered 266 * with B_AGE set will be reallocated more quickly then 267 * buffers encountered without it set. B_AGE is set 268 * as part of the loop so idle buffers should eventually 269 * wind up with B_AGE set. B_AGE explicitly does NOT 270 * cause the buffer to be instantly reallocated for 271 * other purposes. 272 * 273 * Standard buffer flushing routines leave B_AGE intact 274 * through the DIRTY queue and into the CLEAN queue. 275 * Setting B_AGE on a dirty buffer will not cause it 276 * to be flushed more quickly but will cause it to be 277 * reallocated more quickly after having been flushed. 278 * 279 * B_NOCACHE Request that the buffer and backing store be 280 * destroyed on completion. If B_DELWRI is set and the 281 * write fails, the buffer remains intact. 282 * 283 * B_NOTMETA May be set on block device buffers representing 284 * file data (i.e. which aren't really meta-data), 285 * which will cause the buffer cache to set PG_NOTMETA 286 * in the VM pages when releasing them and the 287 * swapcache to not try to cache them. 288 * 289 * B_MARKER Special marker buf, always skip. 290 */ 291 292 #define B_AGE 0x00000001 /* Reuse more quickly */ 293 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */ 294 #define B_NOTMETA 0x00000004 /* This really isn't metadata */ 295 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */ 296 #define B_DEFERRED 0x00000010 /* vfs-controlled deferment */ 297 #define B_CACHE 0x00000020 /* Bread found us in the cache. */ 298 #define B_HASHED 0x00000040 /* Indexed via v_rbhash_tree */ 299 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */ 300 #define B_BNOCLIP 0x00000100 /* EOF clipping b_bcount not allowed */ 301 #define B_HASBOGUS 0x00000200 /* Contains bogus pages */ 302 #define B_EINTR 0x00000400 /* I/O was interrupted */ 303 #define B_ERROR 0x00000800 /* I/O error occurred. */ 304 #define B_IODEBUG 0x00001000 /* (Debugging only bread) */ 305 #define B_INVAL 0x00002000 /* Does not contain valid info. */ 306 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */ 307 #define B_NOCACHE 0x00008000 /* Destroy buffer AND backing store */ 308 #define B_MALLOC 0x00010000 /* malloced b_data */ 309 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */ 310 #define B_MARKER 0x00040000 /* Special marker buf in queue */ 311 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */ 312 #define B_HEAVY 0x00100000 /* Heavy-weight buffer */ 313 #define B_DIRTY 0x00200000 /* Needs writing later. */ 314 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */ 315 #define B_UNUSED23 0x00800000 /* Request wakeup on done */ 316 #define B_VNCLEAN 0x01000000 /* On vnode clean list */ 317 #define B_VNDIRTY 0x02000000 /* On vnode dirty list */ 318 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */ 319 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */ 320 #define B_RAM 0x10000000 /* Read ahead mark (flag) */ 321 #define B_VMIO 0x20000000 /* VMIO flag */ 322 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */ 323 #define B_VFSFLAG1 0x80000000 /* VFSs can set this flag */ 324 325 #define PRINT_BUF_FLAGS "\20" \ 326 "\40unused31\37cluster\36vmio\35ram\34ordered" \ 327 "\33paging\32vndirty\31vnclean\30unused23\27relbuf\26dirty" \ 328 "\25unused20\24raw\23unused18\22clusterok\21malloc\20nocache" \ 329 "\17locked\16inval\15unused12\14error\13eintr\12unused9\11bnoclip" \ 330 "\10delwri\7hashed\6cache\5deferred\4direct\3unused2\2needcommit\1age" 331 332 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */ 333 334 #ifdef _KERNEL 335 /* 336 * Buffer locking. See sys/buf2.h for inline functions. 337 */ 338 extern char *buf_wmesg; /* Default buffer lock message */ 339 #define BUF_WMESG "bufwait" 340 341 #endif /* _KERNEL */ 342 343 struct bio_queue_head { 344 TAILQ_HEAD(bio_queue, bio) queue; 345 off_t off_unused; 346 int reorder; 347 struct bio *transition; 348 struct bio *bio_unused; 349 }; 350 351 /* 352 * This structure describes a clustered I/O. 353 */ 354 struct cluster_save { 355 int bs_nchildren; /* Number of associated buffers. */ 356 struct buf **bs_children; /* List of associated buffers. */ 357 }; 358 359 /* 360 * Zero out the buffer's data area. 361 */ 362 #define clrbuf(bp) { \ 363 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \ 364 (bp)->b_resid = 0; \ 365 } 366 367 /* 368 * Flags to low-level bitmap allocation routines (balloc). 369 * 370 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count 371 * to 127. 372 */ 373 #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */ 374 #define B_SEQSHIFT 24 /* Sequential heuristic shift. */ 375 #define B_SEQMAX 0x7F 376 #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */ 377 #define B_SYNC 0x02 /* Do all allocations synchronously. */ 378 379 #ifdef _KERNEL 380 extern long nbuf; /* The number of buffer headers */ 381 extern long maxswzone; /* Max KVA for swap structures */ 382 extern long maxbcache; /* Max KVA for buffer cache */ 383 extern long hidirtybufspace; 384 extern int buf_maxio; /* nominal maximum I/O for buffer */ 385 extern struct buf *buf; /* The buffer headers. */ 386 extern char *buffers; /* The buffer contents. */ 387 extern int bufpages; /* Number of memory pages in the buffer pool. */ 388 extern struct buf *swbuf; /* Swap I/O buffer headers. */ 389 extern long nswbuf; /* Number of swap I/O buffer headers. */ 390 extern int bioq_reorder_burst_interval; 391 extern int bioq_reorder_burst_bytes; 392 extern int bioq_reorder_minor_interval; 393 extern int bioq_reorder_minor_bytes; 394 395 struct uio; 396 struct devstat; 397 398 long bd_heatup (void); 399 void bd_wait (long count); 400 void waitrunningbufspace(void); 401 int buf_dirty_count_severe (void); 402 int buf_runningbufspace_severe (void); 403 void initbufbio(struct buf *); 404 void uninitbufbio(struct buf *); 405 void reinitbufbio(struct buf *); 406 void clearbiocache(struct bio *); 407 void bremfree (struct buf *); 408 int breadx (struct vnode *, off_t, int, struct buf **); 409 int breadnx (struct vnode *, off_t, int, off_t *, int *, int, 410 struct buf **); 411 void breadcb(struct vnode *, off_t, int, 412 void (*)(struct bio *), void *); 413 int bwrite (struct buf *); 414 void bdwrite (struct buf *); 415 void buwrite (struct buf *); 416 void bawrite (struct buf *); 417 void bdirty (struct buf *); 418 void bheavy (struct buf *); 419 void bundirty (struct buf *); 420 int bowrite (struct buf *); 421 void brelse (struct buf *); 422 void bqrelse (struct buf *); 423 int cluster_awrite (struct buf *); 424 struct buf *getpbuf (int *); 425 struct buf *getpbuf_kva (int *); 426 int inmem (struct vnode *, off_t); 427 struct buf *findblk (struct vnode *, off_t, int); 428 struct buf *getblk (struct vnode *, off_t, int, int, int); 429 struct buf *getcacheblk (struct vnode *, off_t, int, int); 430 struct buf *geteblk (int); 431 struct buf *getnewbuf(int, int, int, int); 432 void bqhold(struct buf *bp); 433 void bqdrop(struct buf *bp); 434 void regetblk(struct buf *bp); 435 struct bio *push_bio(struct bio *); 436 struct bio *pop_bio(struct bio *); 437 int biowait (struct bio *, const char *); 438 int biowait_timeout (struct bio *, const char *, int); 439 void bpdone (struct buf *, int); 440 void biodone (struct bio *); 441 void biodone_sync (struct bio *); 442 void pbuf_adjcount(int *pfreecnt, int n); 443 444 void cluster_append(struct bio *, struct buf *); 445 int cluster_readx (struct vnode *, off_t, off_t, int, 446 size_t, size_t, struct buf **); 447 void cluster_readcb (struct vnode *, off_t, off_t, int, 448 size_t, size_t, void (*func)(struct bio *), void *arg); 449 void cluster_write (struct buf *, off_t, int, int); 450 int physread (struct dev_read_args *); 451 int physwrite (struct dev_write_args *); 452 void vfs_bio_clrbuf (struct buf *); 453 void vfs_busy_pages (struct vnode *, struct buf *); 454 void vfs_unbusy_pages (struct buf *); 455 int vmapbuf (struct buf *, caddr_t, int); 456 void vunmapbuf (struct buf *); 457 void relpbuf (struct buf *, int *); 458 void brelvp (struct buf *); 459 int bgetvp (struct vnode *, struct buf *, int); 460 void bsetrunningbufspace(struct buf *, int); 461 int allocbuf (struct buf *bp, int size); 462 int scan_all_buffers (int (*)(struct buf *, void *), void *); 463 void reassignbuf (struct buf *); 464 struct buf *trypbuf (int *); 465 struct buf *trypbuf_kva (int *); 466 void bio_ops_sync(struct mount *mp); 467 void vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to); 468 void vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to); 469 void nestiobuf_done(struct bio *mbio, int donebytes, int error, struct devstat *stats); 470 void nestiobuf_init(struct bio *mbio); 471 void nestiobuf_add(struct bio *mbio, struct buf *bp, int off, size_t size, struct devstat *stats); 472 void nestiobuf_start(struct bio *mbio); 473 void nestiobuf_error(struct bio *mbio, int error); 474 #endif /* _KERNEL */ 475 #endif /* _KERNEL || _KERNEL_STRUCTURES */ 476 #endif /* !_SYS_BUF_H_ */ 477