aboutsummaryrefslogtreecommitdiff
path: root/sys/sys/buf.h
blob: 012493ca84dc4d43b1513da5eca20e609f6ebc19 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
/*-
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)buf.h	8.9 (Berkeley) 3/30/95
 * $FreeBSD$
 */

#ifndef _SYS_BUF_H_
#define	_SYS_BUF_H_

#include <sys/bufobj.h>
#include <sys/queue.h>
#include <sys/lock.h>
#include <sys/lockmgr.h>

struct bio;
struct buf;
struct bufobj;
struct mount;
struct vnode;
struct uio;

/*
 * To avoid including <ufs/ffs/softdep.h> 
 */   
LIST_HEAD(workhead, worklist);
/*
 * These are currently used only by the soft dependency code, hence
 * are stored once in a global variable. If other subsystems wanted
 * to use these hooks, a pointer to a set of bio_ops could be added
 * to each buffer.
 */
extern struct bio_ops {
	void	(*io_start)(struct buf *);
	void	(*io_complete)(struct buf *);
	void	(*io_deallocate)(struct buf *);
	int	(*io_countdeps)(struct buf *, int);
} bioops;

struct vm_object;

typedef unsigned char b_xflags_t;

/*
 * The buffer header describes an I/O operation in the kernel.
 *
 * NOTES:
 *	b_bufsize, b_bcount.  b_bufsize is the allocation size of the
 *	buffer, either DEV_BSIZE or PAGE_SIZE aligned.  b_bcount is the
 *	originally requested buffer size and can serve as a bounds check
 *	against EOF.  For most, but not all uses, b_bcount == b_bufsize.
 *
 *	b_dirtyoff, b_dirtyend.  Buffers support piecemeal, unaligned
 *	ranges of dirty data that need to be written to backing store.
 *	The range is typically clipped at b_bcount ( not b_bufsize ).
 *
 *	b_resid.  Number of bytes remaining in I/O.  After an I/O operation
 *	completes, b_resid is usually 0 indicating 100% success.
 *
 *	All fields are protected by the buffer lock except those marked:
 *		V - Protected by owning bufobj lock
 *		Q - Protected by the buf queue lock
 *		D - Protected by an dependency implementation specific lock
 */
struct buf {
	struct bufobj	*b_bufobj;
	long		b_bcount;
	void		*b_caller1;
	caddr_t		b_data;
	int		b_error;
	uint8_t		b_iocmd;	/* BIO_* bio_cmd from bio.h */
	uint8_t		b_ioflags;	/* BIO_* bio_flags from bio.h */
	off_t		b_iooffset;
	long		b_resid;
	void	(*b_iodone)(struct buf *);
	daddr_t b_blkno;		/* Underlying physical block number. */
	off_t	b_offset;		/* Offset into file. */
	TAILQ_ENTRY(buf) b_bobufs;	/* (V) Buffer's associated vnode. */
	uint32_t	b_vflags;	/* (V) BV_* flags */
	unsigned short b_qindex;	/* (Q) buffer queue index */
	uint32_t	b_flags;	/* B_* flags. */
	b_xflags_t b_xflags;		/* extra flags */
	struct lock b_lock;		/* Buffer lock */
	long	b_bufsize;		/* Allocated buffer size. */
	int	b_runningbufspace;	/* when I/O is running, pipelining */
	int	b_kvasize;		/* size of kva for buffer */
	int	b_dirtyoff;		/* Offset in buffer of dirty region. */
	int	b_dirtyend;		/* Offset of end of dirty region. */
	caddr_t	b_kvabase;		/* base kva for buffer */
	daddr_t b_lblkno;		/* Logical block number. */
	struct	vnode *b_vp;		/* Device vnode. */
	struct	ucred *b_rcred;		/* Read credentials reference. */
	struct	ucred *b_wcred;		/* Write credentials reference. */
	union {
		TAILQ_ENTRY(buf) b_freelist; /* (Q) */
		struct {
			void	(*b_pgiodone)(void *, vm_page_t *, int, int);
			int	b_pgbefore;
			int	b_pgafter;
		};
	};
	union	cluster_info {
		TAILQ_HEAD(cluster_list_head, buf) cluster_head;
		TAILQ_ENTRY(buf) cluster_entry;
	} b_cluster;
	struct	vm_page *b_pages[btoc(MAXPHYS)];
	int		b_npages;
	struct	workhead b_dep;		/* (D) List of filesystem dependencies. */
	void	*b_fsprivate1;
	void	*b_fsprivate2;
	void	*b_fsprivate3;
	int	b_pin_count;
};

#define b_object	b_bufobj->bo_object

/*
 * These flags are kept in b_flags.
 *
 * Notes:
 *
 *	B_ASYNC		VOP calls on bp's are usually async whether or not
 *			B_ASYNC is set, but some subsystems, such as NFS, like 
 *			to know what is best for the caller so they can
 *			optimize the I/O.
 *
 *	B_PAGING	Indicates that bp is being used by the paging system or
 *			some paging system and that the bp is not linked into
 *			the b_vp's clean/dirty linked lists or ref counts.
 *			Buffer vp reassignments are illegal in this case.
 *
 *	B_CACHE		This may only be set if the buffer is entirely valid.
 *			The situation where B_DELWRI is set and B_CACHE is
 *			clear MUST be committed to disk by getblk() so 
 *			B_DELWRI can also be cleared.  See the comments for
 *			getblk() in kern/vfs_bio.c.  If B_CACHE is clear,
 *			the caller is expected to clear BIO_ERROR and B_INVAL,
 *			set BIO_READ, and initiate an I/O.
 *
 *			The 'entire buffer' is defined to be the range from
 *			0 through b_bcount.
 *
 *	B_MALLOC	Request that the buffer be allocated from the malloc
 *			pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
 *
 *	B_CLUSTEROK	This flag is typically set for B_DELWRI buffers
 *			by filesystems that allow clustering when the buffer
 *			is fully dirty and indicates that it may be clustered
 *			with other adjacent dirty buffers.  Note the clustering
 *			may not be used with the stage 1 data write under NFS
 *			but may be used for the commit rpc portion.
 *
 *	B_VMIO		Indicates that the buffer is tied into an VM object.
 *			The buffer's data is always PAGE_SIZE aligned even
 *			if b_bufsize and b_bcount are not.  ( b_bufsize is 
 *			always at least DEV_BSIZE aligned, though ).
 *
 *	B_DIRECT	Hint that we should attempt to completely free
 *			the pages underlying the buffer.  B_DIRECT is
 *			sticky until the buffer is released and typically
 *			only has an effect when B_RELBUF is also set.
 *
 */

#define	B_AGE		0x00000001	/* Move to age queue when I/O done. */
#define	B_NEEDCOMMIT	0x00000002	/* Append-write in progress. */
#define	B_ASYNC		0x00000004	/* Start I/O, do not wait. */
#define	B_DIRECT	0x00000008	/* direct I/O flag (pls free vmio) */
#define	B_DEFERRED	0x00000010	/* Skipped over for cleaning */
#define	B_CACHE		0x00000020	/* Bread found us in the cache. */
#define	B_VALIDSUSPWRT	0x00000040	/* Valid write during suspension. */
#define	B_DELWRI	0x00000080	/* Delay I/O until buffer reused. */
#define	B_PERSISTENT	0x00000100	/* Perm. ref'ed while EXT2FS mounted. */
#define	B_DONE		0x00000200	/* I/O completed. */
#define	B_EINTR		0x00000400	/* I/O was interrupted */
#define	B_NOREUSE	0x00000800	/* Contents not reused once released. */
#define	B_00001000	0x00001000	/* Available flag. */
#define	B_INVAL		0x00002000	/* Does not contain valid info. */
#define	B_BARRIER	0x00004000	/* Write this and all preceeding first. */
#define	B_NOCACHE	0x00008000	/* Do not cache block after use. */
#define	B_MALLOC	0x00010000	/* malloced b_data */
#define	B_CLUSTEROK	0x00020000	/* Pagein op, so swap() can count it. */
#define	B_00040000	0x00040000	/* Available flag. */
#define	B_00080000	0x00080000	/* Available flag. */
#define	B_00100000	0x00100000	/* Available flag. */
#define	B_DIRTY		0x00200000	/* Needs writing later (in EXT2FS). */
#define	B_RELBUF	0x00400000	/* Release VMIO buffer. */
#define	B_FS_FLAG1	0x00800000	/* Available flag for FS use. */
#define	B_NOCOPY	0x01000000	/* Don't copy-on-write this buf. */
#define	B_INFREECNT	0x02000000	/* buf is counted in numfreebufs */
#define	B_PAGING	0x04000000	/* volatile paging I/O -- bypass VMIO */
#define B_MANAGED	0x08000000	/* Managed by FS. */
#define B_RAM		0x10000000	/* Read ahead mark (flag) */
#define B_VMIO		0x20000000	/* VMIO flag */
#define B_CLUSTER	0x40000000	/* pagein op, so swap() can count it */
#define B_REMFREE	0x80000000	/* Delayed bremfree */

#define PRINT_BUF_FLAGS "\20\40remfree\37cluster\36vmio\35ram\34managed" \
	"\33paging\32infreecnt\31nocopy\30b23\27relbuf\26dirty\25b20" \
	"\24b19\23b18\22clusterok\21malloc\20nocache\17b14\16inval" \
	"\15b12\14noreuse\13eintr\12done\11persist\10delwri" \
	"\7validsuspwrt\6cache\5deferred\4direct\3async\2needcommit\1age"

/*
 * These flags are kept in b_xflags.
 */
#define	BX_VNDIRTY	0x00000001	/* On vnode dirty list */
#define	BX_VNCLEAN	0x00000002	/* On vnode clean list */
#define	BX_BKGRDWRITE	0x00000010	/* Do writes in background */
#define BX_BKGRDMARKER	0x00000020	/* Mark buffer for splay tree */
#define	BX_ALTDATA	0x00000040	/* Holds extended data */

#define	PRINT_BUF_XFLAGS "\20\7altdata\6bkgrdmarker\5bkgrdwrite\2clean\1dirty"

#define	NOOFFSET	(-1LL)		/* No buffer offset calculated yet */

/*
 * These flags are kept in b_vflags.
 */
#define	BV_SCANNED	0x00000001	/* VOP_FSYNC funcs mark written bufs */
#define	BV_BKGRDINPROG	0x00000002	/* Background write in progress */
#define	BV_BKGRDWAIT	0x00000004	/* Background write waiting */
#define	BV_BKGRDERR	0x00000008	/* Error from background write */

#define	PRINT_BUF_VFLAGS "\20\4bkgrderr\3bkgrdwait\2bkgrdinprog\1scanned"

#ifdef _KERNEL
/*
 * Buffer locking
 */
extern const char *buf_wmesg;		/* Default buffer lock message */
#define BUF_WMESG "bufwait"
#include <sys/proc.h>			/* XXX for curthread */
#include <sys/mutex.h>

/*
 * Initialize a lock.
 */
#define BUF_LOCKINIT(bp)						\
	lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, 0)
/*
 *
 * Get a lock sleeping non-interruptably until it becomes available.
 */
#define	BUF_LOCK(bp, locktype, interlock)				\
	_lockmgr_args_rw(&(bp)->b_lock, (locktype), (interlock),	\
	    LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,		\
	    LOCK_FILE, LOCK_LINE)

/*
 * Get a lock sleeping with specified interruptably and timeout.
 */
#define	BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo)	\
	_lockmgr_args_rw(&(bp)->b_lock, (locktype) | LK_TIMELOCK,	\
	    (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo),	\
	    LOCK_FILE, LOCK_LINE)

/*
 * Release a lock. Only the acquiring process may free the lock unless
 * it has been handed off to biodone.
 */
#define	BUF_UNLOCK(bp) do {						\
	KASSERT(((bp)->b_flags & B_REMFREE) == 0,			\
	    ("BUF_UNLOCK %p while B_REMFREE is still set.", (bp)));	\
									\
	(void)_lockmgr_args(&(bp)->b_lock, LK_RELEASE, NULL,		\
	    LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,		\
	    LOCK_FILE, LOCK_LINE);					\
} while (0)

/*
 * Check if a buffer lock is recursed.
 */
#define	BUF_LOCKRECURSED(bp)						\
	lockmgr_recursed(&(bp)->b_lock)

/*
 * Check if a buffer lock is currently held.
 */
#define	BUF_ISLOCKED(bp)						\
	lockstatus(&(bp)->b_lock)
/*
 * Free a buffer lock.
 */
#define BUF_LOCKFREE(bp) 						\
	lockdestroy(&(bp)->b_lock)

/*
 * Print informations on a buffer lock.
 */
#define BUF_LOCKPRINTINFO(bp) 						\
	lockmgr_printinfo(&(bp)->b_lock)

/*
 * Buffer lock assertions.
 */
#if defined(INVARIANTS) && defined(INVARIANT_SUPPORT)
#define	BUF_ASSERT_LOCKED(bp)						\
	_lockmgr_assert(&(bp)->b_lock, KA_LOCKED, LOCK_FILE, LOCK_LINE)
#define	BUF_ASSERT_SLOCKED(bp)						\
	_lockmgr_assert(&(bp)->b_lock, KA_SLOCKED, LOCK_FILE, LOCK_LINE)
#define	BUF_ASSERT_XLOCKED(bp)						\
	_lockmgr_assert(&(bp)->b_lock, KA_XLOCKED, LOCK_FILE, LOCK_LINE)
#define	BUF_ASSERT_UNLOCKED(bp)						\
	_lockmgr_assert(&(bp)->b_lock, KA_UNLOCKED, LOCK_FILE, LOCK_LINE)
#define	BUF_ASSERT_HELD(bp)
#define	BUF_ASSERT_UNHELD(bp)
#else
#define	BUF_ASSERT_LOCKED(bp)
#define	BUF_ASSERT_SLOCKED(bp)
#define	BUF_ASSERT_XLOCKED(bp)
#define	BUF_ASSERT_UNLOCKED(bp)
#define	BUF_ASSERT_HELD(bp)
#define	BUF_ASSERT_UNHELD(bp)
#endif

#ifdef _SYS_PROC_H_	/* Avoid #include <sys/proc.h> pollution */
/*
 * When initiating asynchronous I/O, change ownership of the lock to the
 * kernel. Once done, the lock may legally released by biodone. The
 * original owning process can no longer acquire it recursively, but must
 * wait until the I/O is completed and the lock has been freed by biodone.
 */
#define	BUF_KERNPROC(bp)						\
	_lockmgr_disown(&(bp)->b_lock, LOCK_FILE, LOCK_LINE)
#endif

/*
 * Find out if the lock has waiters or not.
 */
#define	BUF_LOCKWAITERS(bp)						\
	lockmgr_waiters(&(bp)->b_lock)

#endif /* _KERNEL */

struct buf_queue_head {
	TAILQ_HEAD(buf_queue, buf) queue;
	daddr_t last_pblkno;
	struct	buf *insert_point;
	struct	buf *switch_point;
};

/*
 * This structure describes a clustered I/O. 
 */
struct cluster_save {
	long	bs_bcount;		/* Saved b_bcount. */
	long	bs_bufsize;		/* Saved b_bufsize. */
	int	bs_nchildren;		/* Number of associated buffers. */
	struct buf **bs_children;	/* List of associated buffers. */
};

#ifdef _KERNEL

static __inline int
bwrite(struct buf *bp)
{

	KASSERT(bp->b_bufobj != NULL, ("bwrite: no bufobj bp=%p", bp));
	KASSERT(bp->b_bufobj->bo_ops != NULL, ("bwrite: no bo_ops bp=%p", bp));
	KASSERT(bp->b_bufobj->bo_ops->bop_write != NULL,
	    ("bwrite: no bop_write bp=%p", bp));
	return (BO_WRITE(bp->b_bufobj, bp));
}

static __inline void
bstrategy(struct buf *bp)
{

	KASSERT(bp->b_bufobj != NULL, ("bstrategy: no bufobj bp=%p", bp));
	KASSERT(bp->b_bufobj->bo_ops != NULL,
	    ("bstrategy: no bo_ops bp=%p", bp));
	KASSERT(bp->b_bufobj->bo_ops->bop_strategy != NULL,
	    ("bstrategy: no bop_strategy bp=%p", bp));
	BO_STRATEGY(bp->b_bufobj, bp);
}

static __inline void
buf_start(struct buf *bp)
{
	if (bioops.io_start)
		(*bioops.io_start)(bp);
}

static __inline void
buf_complete(struct buf *bp)
{
	if (bioops.io_complete)
		(*bioops.io_complete)(bp);
}

static __inline void
buf_deallocate(struct buf *bp)
{
	if (bioops.io_deallocate)
		(*bioops.io_deallocate)(bp);
}

static __inline int
buf_countdeps(struct buf *bp, int i)
{
	if (bioops.io_countdeps)
		return ((*bioops.io_countdeps)(bp, i));
	else
		return (0);
}

#endif /* _KERNEL */

/*
 * Zero out the buffer's data area.
 */
#define	clrbuf(bp) {							\
	bzero((bp)->b_data, (u_int)(bp)->b_bcount);			\
	(bp)->b_resid = 0;						\
}

/*
 * Flags for getblk's last parameter.
 */
#define	GB_LOCK_NOWAIT	0x0001		/* Fail if we block on a buf lock. */
#define	GB_NOCREAT	0x0002		/* Don't create a buf if not found. */
#define	GB_NOWAIT_BD	0x0004		/* Do not wait for bufdaemon. */
#define	GB_UNMAPPED	0x0008		/* Do not mmap buffer pages. */
#define	GB_KVAALLOC	0x0010		/* But allocate KVA. */

#ifdef _KERNEL
extern int	nbuf;			/* The number of buffer headers */
extern long	maxswzone;		/* Max KVA for swap structures */
extern long	maxbcache;		/* Max KVA for buffer cache */
extern long	runningbufspace;
extern long	hibufspace;
extern int	dirtybufthresh;
extern int	bdwriteskip;
extern int	dirtybufferflushes;
extern int	altbufferflushes;
extern int	nswbuf;			/* Number of swap I/O buffer headers. */
extern int	cluster_pbuf_freecnt;	/* Number of pbufs for clusters */
extern int	vnode_pbuf_freecnt;	/* Number of pbufs for vnode pager */
extern int	vnode_async_pbuf_freecnt; /* Number of pbufs for vnode pager,
					     asynchronous reads */
extern caddr_t	unmapped_buf;	/* Data address for unmapped buffers. */

static inline int
buf_mapped(struct buf *bp)
{

	return (bp->b_data != unmapped_buf);
}

void	runningbufwakeup(struct buf *);
void	waitrunningbufspace(void);
caddr_t	kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est);
void	bufinit(void);
void	bufshutdown(int);
void	bdata2bio(struct buf *bp, struct bio *bip);
void	bwillwrite(void);
int	buf_dirty_count_severe(void);
void	bremfree(struct buf *);
void	bremfreef(struct buf *);	/* XXX Force bremfree, only for nfs. */
#define bread(vp, blkno, size, cred, bpp) \
	    breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, 0, bpp)
#define bread_gb(vp, blkno, size, cred, gbflags, bpp) \
	    breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, \
		gbflags, bpp)
#define breadn(vp, blkno, size, rablkno, rabsize, cnt, cred, bpp) \
	    breadn_flags(vp, blkno, size, rablkno, rabsize, cnt, cred, 0, bpp)
int	breadn_flags(struct vnode *, daddr_t, int, daddr_t *, int *, int,
	    struct ucred *, int, struct buf **);
void	breada(struct vnode *, daddr_t *, int *, int, struct ucred *);
void	bdwrite(struct buf *);
void	bawrite(struct buf *);
void	babarrierwrite(struct buf *);
int	bbarrierwrite(struct buf *);
void	bdirty(struct buf *);
void	bundirty(struct buf *);
void	bufstrategy(struct bufobj *, struct buf *);
void	brelse(struct buf *);
void	bqrelse(struct buf *);
int	vfs_bio_awrite(struct buf *);
void	vfs_drain_busy_pages(struct buf *bp);
struct buf *     getpbuf(int *);
struct buf *incore(struct bufobj *, daddr_t);
struct buf *gbincore(struct bufobj *, daddr_t);
struct buf *getblk(struct vnode *, daddr_t, int, int, int, int);
struct buf *geteblk(int, int);
int	bufwait(struct buf *);
int	bufwrite(struct buf *);
void	bufdone(struct buf *);
void	bufdone_finish(struct buf *);
void	bd_speedup(void);

int	cluster_read(struct vnode *, u_quad_t, daddr_t, long,
	    struct ucred *, long, int, int, struct buf **);
int	cluster_wbuild(struct vnode *, long, daddr_t, int, int);
void	cluster_write(struct vnode *, struct buf *, u_quad_t, int, int);
void	vfs_bio_bzero_buf(struct buf *bp, int base, int size);
void	vfs_bio_set_valid(struct buf *, int base, int size);
void	vfs_bio_clrbuf(struct buf *);
void	vfs_busy_pages(struct buf *, int clear_modify);
void	vfs_unbusy_pages(struct buf *);
int	vmapbuf(struct buf *, int);
void	vunmapbuf(struct buf *);
void	relpbuf(struct buf *, int *);
void	brelvp(struct buf *);
void	bgetvp(struct vnode *, struct buf *);
void	pbgetbo(struct bufobj *bo, struct buf *bp);
void	pbgetvp(struct vnode *, struct buf *);
void	pbrelbo(struct buf *);
void	pbrelvp(struct buf *);
int	allocbuf(struct buf *bp, int size);
void	reassignbuf(struct buf *);
struct	buf *trypbuf(int *);
void	bwait(struct buf *, u_char, const char *);
void	bdone(struct buf *);
void	bpin(struct buf *);
void	bunpin(struct buf *);
void 	bunpin_wait(struct buf *);

#endif /* _KERNEL */

#endif /* !_SYS_BUF_H_ */