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 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)buf.h 8.9 (Berkeley) 3/30/95 35 * $FreeBSD$ 36 */ 37 38 #ifndef _SYS_BUF_H_ 39 #define _SYS_BUF_H_ 40 41 #include <sys/bufobj.h> 42 #include <sys/queue.h> 43 #include <sys/lock.h> 44 #include <sys/lockmgr.h> 45 46 struct bio; 47 struct buf; 48 struct bufobj; 49 struct mount; 50 struct vnode; 51 struct uio; 52 53 /* 54 * To avoid including <ufs/ffs/softdep.h> 55 */ 56 LIST_HEAD(workhead, worklist); 57 /* 58 * These are currently used only by the soft dependency code, hence 59 * are stored once in a global variable. If other subsystems wanted 60 * to use these hooks, a pointer to a set of bio_ops could be added 61 * to each buffer. 62 */ 63 extern struct bio_ops { 64 void (*io_start)(struct buf *); 65 void (*io_complete)(struct buf *); 66 void (*io_deallocate)(struct buf *); 67 int (*io_countdeps)(struct buf *, int); 68 } bioops; 69 70 struct vm_object; 71 72 typedef unsigned char b_xflags_t; 73 74 /* 75 * The buffer header describes an I/O operation in the kernel. 76 * 77 * NOTES: 78 * b_bufsize, b_bcount. b_bufsize is the allocation size of the 79 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the 80 * originally requested buffer size and can serve as a bounds check 81 * against EOF. For most, but not all uses, b_bcount == b_bufsize. 82 * 83 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned 84 * ranges of dirty data that need to be written to backing store. 85 * The range is typically clipped at b_bcount ( not b_bufsize ). 86 * 87 * b_resid. Number of bytes remaining in I/O. After an I/O operation 88 * completes, b_resid is usually 0 indicating 100% success. 89 * 90 * All fields are protected by the buffer lock except those marked: 91 * V - Protected by owning bufobj lock 92 * Q - Protected by the buf queue lock 93 * D - Protected by an dependency implementation specific lock 94 */ 95 struct buf { 96 struct bufobj *b_bufobj; 97 long b_bcount; 98 void *b_caller1; 99 caddr_t b_data; 100 int b_error; 101 uint8_t b_iocmd; 102 uint8_t b_ioflags; 103 off_t b_iooffset; 104 long b_resid; 105 void (*b_iodone)(struct buf *); 106 daddr_t b_blkno; /* Underlying physical block number. */ 107 off_t b_offset; /* Offset into file. */ 108 TAILQ_ENTRY(buf) b_bobufs; /* (V) Buffer's associated vnode. */ 109 struct buf *b_left; /* (V) splay tree link */ 110 struct buf *b_right; /* (V) splay tree link */ 111 uint32_t b_vflags; /* (V) BV_* flags */ 112 TAILQ_ENTRY(buf) b_freelist; /* (Q) Free list position inactive. */ 113 unsigned short b_qindex; /* (Q) buffer queue index */ 114 uint32_t b_flags; /* B_* flags. */ 115 b_xflags_t b_xflags; /* extra flags */ 116 struct lock b_lock; /* Buffer lock */ 117 long b_bufsize; /* Allocated buffer size. */ 118 long b_runningbufspace; /* when I/O is running, pipelining */ 119 caddr_t b_kvabase; /* base kva for buffer */ 120 int b_kvasize; /* size of kva for buffer */ 121 daddr_t b_lblkno; /* Logical block number. */ 122 struct vnode *b_vp; /* Device vnode. */ 123 int b_dirtyoff; /* Offset in buffer of dirty region. */ 124 int b_dirtyend; /* Offset of end of dirty region. */ 125 struct ucred *b_rcred; /* Read credentials reference. */ 126 struct ucred *b_wcred; /* Write credentials reference. */ 127 void *b_saveaddr; /* Original b_addr for physio. */ 128 union pager_info { 129 int pg_reqpage; 130 } b_pager; 131 union cluster_info { 132 TAILQ_HEAD(cluster_list_head, buf) cluster_head; 133 TAILQ_ENTRY(buf) cluster_entry; 134 } b_cluster; 135 struct vm_page *b_pages[btoc(MAXPHYS)]; 136 int b_npages; 137 struct workhead b_dep; /* (D) List of filesystem dependencies. */ 138 void *b_fsprivate1; 139 void *b_fsprivate2; 140 void *b_fsprivate3; 141 int b_pin_count; 142 }; 143 144 #define b_object b_bufobj->bo_object 145 146 /* 147 * These flags are kept in b_flags. 148 * 149 * Notes: 150 * 151 * B_ASYNC VOP calls on bp's are usually async whether or not 152 * B_ASYNC is set, but some subsystems, such as NFS, like 153 * to know what is best for the caller so they can 154 * optimize the I/O. 155 * 156 * B_PAGING Indicates that bp is being used by the paging system or 157 * some paging system and that the bp is not linked into 158 * the b_vp's clean/dirty linked lists or ref counts. 159 * Buffer vp reassignments are illegal in this case. 160 * 161 * B_CACHE This may only be set if the buffer is entirely valid. 162 * The situation where B_DELWRI is set and B_CACHE is 163 * clear MUST be committed to disk by getblk() so 164 * B_DELWRI can also be cleared. See the comments for 165 * getblk() in kern/vfs_bio.c. If B_CACHE is clear, 166 * the caller is expected to clear BIO_ERROR and B_INVAL, 167 * set BIO_READ, and initiate an I/O. 168 * 169 * The 'entire buffer' is defined to be the range from 170 * 0 through b_bcount. 171 * 172 * B_MALLOC Request that the buffer be allocated from the malloc 173 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned. 174 * 175 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers 176 * by filesystems that allow clustering when the buffer 177 * is fully dirty and indicates that it may be clustered 178 * with other adjacent dirty buffers. Note the clustering 179 * may not be used with the stage 1 data write under NFS 180 * but may be used for the commit rpc portion. 181 * 182 * B_VMIO Indicates that the buffer is tied into an VM object. 183 * The buffer's data is always PAGE_SIZE aligned even 184 * if b_bufsize and b_bcount are not. ( b_bufsize is 185 * always at least DEV_BSIZE aligned, though ). 186 * 187 * B_DIRECT Hint that we should attempt to completely free 188 * the pages underlying the buffer. B_DIRECT is 189 * sticky until the buffer is released and typically 190 * only has an effect when B_RELBUF is also set. 191 * 192 */ 193 194 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */ 195 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */ 196 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */ 197 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */ 198 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */ 199 #define B_CACHE 0x00000020 /* Bread found us in the cache. */ 200 #define B_VALIDSUSPWRT 0x00000040 /* Valid write during suspension. */ 201 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */ 202 #define B_PERSISTENT 0x00000100 /* Perm. ref'ed while EXT2FS mounted. */ 203 #define B_DONE 0x00000200 /* I/O completed. */ 204 #define B_EINTR 0x00000400 /* I/O was interrupted */ 205 #define B_00000800 0x00000800 /* Available flag. */ 206 #define B_00001000 0x00001000 /* Available flag. */ 207 #define B_INVAL 0x00002000 /* Does not contain valid info. */ 208 #define B_00004000 0x00004000 /* Available flag. */ 209 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */ 210 #define B_MALLOC 0x00010000 /* malloced b_data */ 211 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */ 212 #define B_000400000 0x00040000 /* Available flag. */ 213 #define B_000800000 0x00080000 /* Available flag. */ 214 #define B_00100000 0x00100000 /* Available flag. */ 215 #define B_DIRTY 0x00200000 /* Needs writing later (in EXT2FS). */ 216 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */ 217 #define B_00800000 0x00800000 /* Available flag. */ 218 #define B_NOCOPY 0x01000000 /* Don't copy-on-write this buf. */ 219 #define B_NEEDSGIANT 0x02000000 /* Buffer's vnode needs giant. */ 220 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */ 221 #define B_MANAGED 0x08000000 /* Managed by FS. */ 222 #define B_RAM 0x10000000 /* Read ahead mark (flag) */ 223 #define B_VMIO 0x20000000 /* VMIO flag */ 224 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */ 225 #define B_REMFREE 0x80000000 /* Delayed bremfree */ 226 227 #define PRINT_BUF_FLAGS "\20\40remfree\37cluster\36vmio\35ram\34b27" \ 228 "\33paging\32b25\31b24\30b23\27relbuf\26dirty\25b20" \ 229 "\24b19\23b18\22clusterok\21malloc\20nocache\17b14\16inval" \ 230 "\15b12\14b11\13eintr\12done\11persist\10delwri\7validsuspwrt" \ 231 "\6cache\5deferred\4direct\3async\2needcommit\1age" 232 233 /* 234 * These flags are kept in b_xflags. 235 */ 236 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */ 237 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */ 238 #define BX_BKGRDWRITE 0x00000010 /* Do writes in background */ 239 #define BX_BKGRDMARKER 0x00000020 /* Mark buffer for splay tree */ 240 #define BX_ALTDATA 0x00000040 /* Holds extended data */ 241 242 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */ 243 244 /* 245 * These flags are kept in b_vflags. 246 */ 247 #define BV_SCANNED 0x00000001 /* VOP_FSYNC funcs mark written bufs */ 248 #define BV_BKGRDINPROG 0x00000002 /* Background write in progress */ 249 #define BV_BKGRDWAIT 0x00000004 /* Background write waiting */ 250 #define BV_INFREECNT 0x80000000 /* buf is counted in numfreebufs */ 251 252 #ifdef _KERNEL 253 /* 254 * Buffer locking 255 */ 256 extern const char *buf_wmesg; /* Default buffer lock message */ 257 #define BUF_WMESG "bufwait" 258 #include <sys/proc.h> /* XXX for curthread */ 259 #include <sys/mutex.h> 260 261 /* 262 * Initialize a lock. 263 */ 264 #define BUF_LOCKINIT(bp) \ 265 lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, 0) 266 /* 267 * 268 * Get a lock sleeping non-interruptably until it becomes available. 269 */ 270 #define BUF_LOCK(bp, locktype, interlock) \ 271 _lockmgr_args(&(bp)->b_lock, (locktype), (interlock), \ 272 LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, \ 273 LOCK_FILE, LOCK_LINE) 274 275 /* 276 * Get a lock sleeping with specified interruptably and timeout. 277 */ 278 #define BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo) \ 279 _lockmgr_args(&(bp)->b_lock, (locktype) | LK_TIMELOCK, \ 280 (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo), \ 281 LOCK_FILE, LOCK_LINE) 282 283 /* 284 * Release a lock. Only the acquiring process may free the lock unless 285 * it has been handed off to biodone. 286 */ 287 #define BUF_UNLOCK(bp) do { \ 288 KASSERT(((bp)->b_flags & B_REMFREE) == 0, \ 289 ("BUF_UNLOCK %p while B_REMFREE is still set.", (bp))); \ 290 \ 291 (void)_lockmgr_args(&(bp)->b_lock, LK_RELEASE, NULL, \ 292 LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, \ 293 LOCK_FILE, LOCK_LINE); \ 294 } while (0) 295 296 /* 297 * Check if a buffer lock is recursed. 298 */ 299 #define BUF_LOCKRECURSED(bp) \ 300 lockmgr_recursed(&(bp)->b_lock) 301 302 /* 303 * Check if a buffer lock is currently held. 304 */ 305 #define BUF_ISLOCKED(bp) \ 306 lockstatus(&(bp)->b_lock) 307 /* 308 * Free a buffer lock. 309 */ 310 #define BUF_LOCKFREE(bp) \ 311 lockdestroy(&(bp)->b_lock) 312 313 /* 314 * Buffer lock assertions. 315 */ 316 #if defined(INVARIANTS) && defined(INVARIANT_SUPPORT) 317 #define BUF_ASSERT_LOCKED(bp) \ 318 _lockmgr_assert(&(bp)->b_lock, KA_LOCKED, LOCK_FILE, LOCK_LINE) 319 #define BUF_ASSERT_SLOCKED(bp) \ 320 _lockmgr_assert(&(bp)->b_lock, KA_SLOCKED, LOCK_FILE, LOCK_LINE) 321 #define BUF_ASSERT_XLOCKED(bp) \ 322 _lockmgr_assert(&(bp)->b_lock, KA_XLOCKED, LOCK_FILE, LOCK_LINE) 323 #define BUF_ASSERT_UNLOCKED(bp) \ 324 _lockmgr_assert(&(bp)->b_lock, KA_UNLOCKED, LOCK_FILE, LOCK_LINE) 325 #define BUF_ASSERT_HELD(bp) 326 #define BUF_ASSERT_UNHELD(bp) 327 #else 328 #define BUF_ASSERT_LOCKED(bp) 329 #define BUF_ASSERT_SLOCKED(bp) 330 #define BUF_ASSERT_XLOCKED(bp) 331 #define BUF_ASSERT_UNLOCKED(bp) 332 #define BUF_ASSERT_HELD(bp) 333 #define BUF_ASSERT_UNHELD(bp) 334 #endif 335 336 #ifdef _SYS_PROC_H_ /* Avoid #include <sys/proc.h> pollution */ 337 /* 338 * When initiating asynchronous I/O, change ownership of the lock to the 339 * kernel. Once done, the lock may legally released by biodone. The 340 * original owning process can no longer acquire it recursively, but must 341 * wait until the I/O is completed and the lock has been freed by biodone. 342 */ 343 #define BUF_KERNPROC(bp) \ 344 _lockmgr_disown(&(bp)->b_lock, LOCK_FILE, LOCK_LINE) 345 #endif 346 347 /* 348 * Find out if the lock has waiters or not. 349 */ 350 #define BUF_LOCKWAITERS(bp) \ 351 lockmgr_waiters(&(bp)->b_lock) 352 353 #endif /* _KERNEL */ 354 355 struct buf_queue_head { 356 TAILQ_HEAD(buf_queue, buf) queue; 357 daddr_t last_pblkno; 358 struct buf *insert_point; 359 struct buf *switch_point; 360 }; 361 362 /* 363 * This structure describes a clustered I/O. It is stored in the b_saveaddr 364 * field of the buffer on which I/O is done. At I/O completion, cluster 365 * callback uses the structure to parcel I/O's to individual buffers, and 366 * then free's this structure. 367 */ 368 struct cluster_save { 369 long bs_bcount; /* Saved b_bcount. */ 370 long bs_bufsize; /* Saved b_bufsize. */ 371 void *bs_saveaddr; /* Saved b_addr. */ 372 int bs_nchildren; /* Number of associated buffers. */ 373 struct buf **bs_children; /* List of associated buffers. */ 374 }; 375 376 #ifdef _KERNEL 377 378 static __inline int 379 bwrite(struct buf *bp) 380 { 381 382 KASSERT(bp->b_bufobj != NULL, ("bwrite: no bufobj bp=%p", bp)); 383 KASSERT(bp->b_bufobj->bo_ops != NULL, ("bwrite: no bo_ops bp=%p", bp)); 384 KASSERT(bp->b_bufobj->bo_ops->bop_write != NULL, 385 ("bwrite: no bop_write bp=%p", bp)); 386 return (BO_WRITE(bp->b_bufobj, bp)); 387 } 388 389 static __inline void 390 bstrategy(struct buf *bp) 391 { 392 393 KASSERT(bp->b_bufobj != NULL, ("bstrategy: no bufobj bp=%p", bp)); 394 KASSERT(bp->b_bufobj->bo_ops != NULL, 395 ("bstrategy: no bo_ops bp=%p", bp)); 396 KASSERT(bp->b_bufobj->bo_ops->bop_strategy != NULL, 397 ("bstrategy: no bop_strategy bp=%p", bp)); 398 BO_STRATEGY(bp->b_bufobj, bp); 399 } 400 401 static __inline void 402 buf_start(struct buf *bp) 403 { 404 if (bioops.io_start) 405 (*bioops.io_start)(bp); 406 } 407 408 static __inline void 409 buf_complete(struct buf *bp) 410 { 411 if (bioops.io_complete) 412 (*bioops.io_complete)(bp); 413 } 414 415 static __inline void 416 buf_deallocate(struct buf *bp) 417 { 418 if (bioops.io_deallocate) 419 (*bioops.io_deallocate)(bp); 420 BUF_LOCKFREE(bp); 421 } 422 423 static __inline int 424 buf_countdeps(struct buf *bp, int i) 425 { 426 if (bioops.io_countdeps) 427 return ((*bioops.io_countdeps)(bp, i)); 428 else 429 return (0); 430 } 431 432 #endif /* _KERNEL */ 433 434 /* 435 * Zero out the buffer's data area. 436 */ 437 #define clrbuf(bp) { \ 438 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \ 439 (bp)->b_resid = 0; \ 440 } 441 442 /* 443 * Flags for getblk's last parameter. 444 */ 445 #define GB_LOCK_NOWAIT 0x0001 /* Fail if we block on a buf lock. */ 446 #define GB_NOCREAT 0x0002 /* Don't create a buf if not found. */ 447 #define GB_NOWAIT_BD 0x0004 /* Do not wait for bufdaemon */ 448 449 #ifdef _KERNEL 450 extern int nbuf; /* The number of buffer headers */ 451 extern long maxswzone; /* Max KVA for swap structures */ 452 extern long maxbcache; /* Max KVA for buffer cache */ 453 extern long runningbufspace; 454 extern long hibufspace; 455 extern int dirtybufthresh; 456 extern int bdwriteskip; 457 extern int dirtybufferflushes; 458 extern int altbufferflushes; 459 extern int buf_maxio; /* nominal maximum I/O for buffer */ 460 extern struct buf *buf; /* The buffer headers. */ 461 extern char *buffers; /* The buffer contents. */ 462 extern int bufpages; /* Number of memory pages in the buffer pool. */ 463 extern struct buf *swbuf; /* Swap I/O buffer headers. */ 464 extern int nswbuf; /* Number of swap I/O buffer headers. */ 465 extern int cluster_pbuf_freecnt; /* Number of pbufs for clusters */ 466 extern int vnode_pbuf_freecnt; /* Number of pbufs for vnode pager */ 467 468 void runningbufwakeup(struct buf *); 469 void waitrunningbufspace(void); 470 caddr_t kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est); 471 void bufinit(void); 472 void bwillwrite(void); 473 int buf_dirty_count_severe(void); 474 void bremfree(struct buf *); 475 void bremfreef(struct buf *); /* XXX Force bremfree, only for nfs. */ 476 int bread(struct vnode *, daddr_t, int, struct ucred *, struct buf **); 477 void breada(struct vnode *, daddr_t *, int *, int, struct ucred *); 478 int breadn(struct vnode *, daddr_t, int, daddr_t *, int *, int, 479 struct ucred *, struct buf **); 480 void bdwrite(struct buf *); 481 void bawrite(struct buf *); 482 void bdirty(struct buf *); 483 void bundirty(struct buf *); 484 void bufstrategy(struct bufobj *, struct buf *); 485 void brelse(struct buf *); 486 void bqrelse(struct buf *); 487 int vfs_bio_awrite(struct buf *); 488 struct buf * getpbuf(int *); 489 struct buf *incore(struct bufobj *, daddr_t); 490 struct buf *gbincore(struct bufobj *, daddr_t); 491 struct buf *getblk(struct vnode *, daddr_t, int, int, int, int); 492 struct buf *geteblk(int, int); 493 int bufwait(struct buf *); 494 int bufwrite(struct buf *); 495 void bufdone(struct buf *); 496 void bufdone_finish(struct buf *); 497 void bd_speedup(void); 498 499 int cluster_read(struct vnode *, u_quad_t, daddr_t, long, 500 struct ucred *, long, int, struct buf **); 501 int cluster_wbuild(struct vnode *, long, daddr_t, int); 502 void cluster_write(struct vnode *, struct buf *, u_quad_t, int); 503 void vfs_bio_set_valid(struct buf *, int base, int size); 504 void vfs_bio_clrbuf(struct buf *); 505 void vfs_busy_pages(struct buf *, int clear_modify); 506 void vfs_unbusy_pages(struct buf *); 507 int vmapbuf(struct buf *); 508 void vunmapbuf(struct buf *); 509 void relpbuf(struct buf *, int *); 510 void brelvp(struct buf *); 511 void bgetvp(struct vnode *, struct buf *); 512 void pbgetbo(struct bufobj *bo, struct buf *bp); 513 void pbgetvp(struct vnode *, struct buf *); 514 void pbrelbo(struct buf *); 515 void pbrelvp(struct buf *); 516 int allocbuf(struct buf *bp, int size); 517 void reassignbuf(struct buf *); 518 struct buf *trypbuf(int *); 519 void bwait(struct buf *, u_char, const char *); 520 void bdone(struct buf *); 521 void bpin(struct buf *); 522 void bunpin(struct buf *); 523 void bunpin_wait(struct buf *); 524 525 #endif /* _KERNEL */ 526 527 #endif /* !_SYS_BUF_H_ */ 528