* Add a missing kernel option and a VGA spec reference.
[dragonfly.git] / sys / sys / buf.h
CommitLineData
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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 $
27bc0cb1 40 * $DragonFly: src/sys/sys/buf.h,v 1.41 2007/11/07 00:46:38 dillon Exp $
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41 */
42
43#ifndef _SYS_BUF_H_
44#define _SYS_BUF_H_
45
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46#if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)
47
335dda38 48#ifndef _SYS_QUEUE_H_
984263bc 49#include <sys/queue.h>
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50#endif
51#ifndef _SYS_LOCK_H_
984263bc 52#include <sys/lock.h>
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53#endif
54#ifndef _SYS_DEVICE_H_
55#include <sys/device.h>
56#endif
984263bc 57
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58#ifndef _SYS_XIO_H_
59#include <sys/xio.h>
60#endif
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61#ifndef _SYS_TREE_H_
62#include <sys/tree.h>
63#endif
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64#ifndef _SYS_BIO_H_
65#include <sys/bio.h>
66#endif
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67#ifndef _SYS_SPINLOCK_H_
68#include <sys/spinlock.h>
69#endif
1eabbf32 70
984263bc 71struct buf;
81b5c339 72struct bio;
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73struct mount;
74struct vnode;
54f51aeb 75struct xio;
984263bc 76
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77#define NBUF_BIO 4
78
6bae6177 79struct buf_rb_tree;
1f1ea522 80struct buf_rb_hash;
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81RB_PROTOTYPE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, off_t);
82RB_PROTOTYPE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, off_t);
6bae6177 83
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84/*
85 * To avoid including <ufs/ffs/softdep.h>
86 */
87LIST_HEAD(workhead, worklist);
984263bc 88
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89typedef enum buf_cmd {
90 BUF_CMD_DONE = 0,
91 BUF_CMD_READ,
92 BUF_CMD_WRITE,
93 BUF_CMD_FREEBLKS,
94 BUF_CMD_FORMAT
95} buf_cmd_t;
96
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97/*
98 * The buffer header describes an I/O operation in the kernel.
99 *
100 * NOTES:
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101 * b_bufsize represents the filesystem block size (for this particular
102 * block) and/or the allocation size or original request size. This
103 * field is NOT USED by lower device layers. VNode and device
104 * strategy routines WILL NEVER ACCESS THIS FIELD.
984263bc 105 *
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106 * b_bcount represents the I/O request size. Unless B_NOBCLIP is set,
107 * the device chain is allowed to clip b_bcount to accomodate the device
108 * EOF. Note that this is different from the byte oriented file EOF.
109 * If B_NOBCLIP is set, the device chain is required to generate an
110 * error if it would othrewise have to clip the request. Buffers
111 * obtained via getblk() automatically set B_NOBCLIP. It is important
112 * to note that EOF clipping via b_bcount is different from EOF clipping
113 * via returning a b_actual < b_bcount. B_NOBCLIP only effects block
114 * oriented EOF clipping (b_bcount modifications).
984263bc 115 *
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116 * b_actual represents the number of bytes of I/O that actually occured,
117 * whether an error occured or not. b_actual must be initialized to 0
118 * prior to initiating I/O as the device drivers will assume it to
119 * start at 0.
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120 *
121 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
122 * ranges of dirty data that need to be written to backing store.
123 * The range is typically clipped at b_bcount (not b_bufsize).
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124 *
125 * b_bio1 and b_bio2 represent the two primary I/O layers. Additional
126 * I/O layers are allocated out of the object cache and may also exist.
127 *
128 * b_bio1 is the logical layer and contains offset or block number
129 * data for the primary vnode, b_vp. I/O operations are almost
130 * universally initiated from the logical layer, so you will often
131 * see things like: vn_strategy(bp->b_vp, &bp->b_bio1).
132 *
133 * b_bio2 is the first physical layer (typically the slice-relative
134 * layer) and contains the translated offset or block number for
135 * the block device underlying a filesystem. Filesystems such as UFS
136 * will maintain cached translations and you may see them initiate
137 * a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2). BUT,
138 * remember that the layering is relative to bp->b_vp, so the
139 * device-relative block numbers for buffer cache operations that occur
140 * directly on a block device will be in the first BIO layer.
141 *
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142 * b_ops - initialized if a buffer has a bio_ops
143 *
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144 * NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly.
145 * ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO
146 * PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE
147 * I/O DEEPER. In particular, a vn_strategy() or dev_dstrategy()
148 * call should not ever access buf->b_vp as this vnode may be totally
149 * unrelated to the vnode/device whos strategy routine was called.
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150 */
151struct buf {
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152 RB_ENTRY(buf) b_rbnode; /* RB node in vnode clean/dirty tree */
153 RB_ENTRY(buf) b_rbhash; /* RB node in vnode hash tree */
984263bc 154 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
81b5c339 155 struct buf *b_cluster_next; /* Next buffer (cluster code) */
54078292 156 struct vnode *b_vp; /* (vp, loffset) index */
81b5c339 157 struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */
54078292 158 u_int32_t b_flags; /* B_* flags. */
984263bc 159 unsigned short b_qindex; /* buffer queue index */
9e45bec7 160 unsigned short b_unused01;
984263bc 161 struct lock b_lock; /* Buffer lock */
10f3fee5 162 buf_cmd_t b_cmd; /* I/O command */
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163 int b_bufsize; /* Allocated buffer size. */
164 int b_runningbufspace; /* when I/O is running, pipelining */
165 int b_bcount; /* Valid bytes in buffer. */
166 int b_resid; /* Remaining I/O */
81b5c339 167 int b_error; /* Error return */
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168 caddr_t b_data; /* Memory, superblocks, indirect etc. */
169 caddr_t b_kvabase; /* base kva for buffer */
170 int b_kvasize; /* size of kva for buffer */
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171 int b_dirtyoff; /* Offset in buffer of dirty region. */
172 int b_dirtyend; /* Offset of end of dirty region. */
81b5c339 173 struct xio b_xio; /* data buffer page list management */
408357d8 174 struct bio_ops *b_ops; /* bio_ops used w/ b_dep */
984263bc 175 struct workhead b_dep; /* List of filesystem dependencies. */
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176};
177
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178/*
179 * XXX temporary
180 */
181#define b_bio1 b_bio_array[0] /* logical layer */
182#define b_bio2 b_bio_array[1] /* (typically) the disk layer */
183#define b_loffset b_bio1.bio_offset
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184
185/*
186 * These flags are kept in b_flags.
187 *
188 * Notes:
189 *
190 * B_ASYNC VOP calls on bp's are usually async whether or not
191 * B_ASYNC is set, but some subsystems, such as NFS, like
192 * to know what is best for the caller so they can
193 * optimize the I/O.
194 *
195 * B_PAGING Indicates that bp is being used by the paging system or
196 * some paging system and that the bp is not linked into
197 * the b_vp's clean/dirty linked lists or ref counts.
198 * Buffer vp reassignments are illegal in this case.
199 *
200 * B_CACHE This may only be set if the buffer is entirely valid.
201 * The situation where B_DELWRI is set and B_CACHE is
202 * clear MUST be committed to disk by getblk() so
203 * B_DELWRI can also be cleared. See the comments for
204 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
205 * the caller is expected to clear B_ERROR|B_INVAL,
10f3fee5 206 * set BUF_CMD_READ, and initiate an I/O.
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207 *
208 * The 'entire buffer' is defined to be the range from
209 * 0 through b_bcount.
210 *
211 * B_MALLOC Request that the buffer be allocated from the malloc
212 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
213 *
214 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
215 * by filesystems that allow clustering when the buffer
216 * is fully dirty and indicates that it may be clustered
217 * with other adjacent dirty buffers. Note the clustering
218 * may not be used with the stage 1 data write under NFS
219 * but may be used for the commit rpc portion.
220 *
221 * B_VMIO Indicates that the buffer is tied into an VM object.
222 * The buffer's data is always PAGE_SIZE aligned even
223 * if b_bufsize and b_bcount are not. ( b_bufsize is
224 * always at least DEV_BSIZE aligned, though ).
225 *
226 * B_DIRECT Hint that we should attempt to completely free
227 * the pages underlying the buffer. B_DIRECT is
228 * sticky until the buffer is released and typically
229 * only has an effect when B_RELBUF is also set.
230 *
231 * B_NOWDRAIN This flag should be set when a device (like VN)
232 * does a turn-around VOP_WRITE from its strategy
233 * routine. This flag prevents bwrite() from blocking
234 * in wdrain, avoiding a deadlock situation.
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235 *
236 * B_LOCKED The buffer will be released to the locked queue
237 * regardless of its current state. Note that
238 * if B_DELWRI is set, no I/O occurs until the caller
239 * acquires the buffer, clears B_LOCKED, then releases
240 * it again.
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241 */
242
243#define B_AGE 0x00000001 /* Move to age queue when I/O done. */
244#define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
245#define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
246#define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
247#define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
248#define B_CACHE 0x00000020 /* Bread found us in the cache. */
1f1ea522 249#define B_HASHED 0x00000040 /* Indexed via v_rbhash_tree */
984263bc 250#define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
4414f2c9 251#define B_BNOCLIP 0x00000100 /* EOF clipping b_bcount not allowed */
10f3fee5 252#define B_UNUSED0200 0x00000200
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253#define B_EINTR 0x00000400 /* I/O was interrupted */
254#define B_ERROR 0x00000800 /* I/O error occurred. */
71bc1d95 255#define B_UNUSED1000 0x00001000 /* Unused */
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256#define B_INVAL 0x00002000 /* Does not contain valid info. */
257#define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
135bd6a8 258#define B_NOCACHE 0x00008000 /* Destroy buffer AND backing store */
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259#define B_MALLOC 0x00010000 /* malloced b_data */
260#define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
9fd739f4 261#define B_UNUSED40000 0x00040000
984263bc 262#define B_RAW 0x00080000 /* Set by physio for raw transfers. */
9e45bec7 263#define B_UNUSED100000 0x00100000
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264#define B_DIRTY 0x00200000 /* Needs writing later. */
265#define B_RELBUF 0x00400000 /* Release VMIO buffer. */
266#define B_WANT 0x00800000 /* Used by vm_pager.c */
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267#define B_VNCLEAN 0x01000000 /* On vnode clean list */
268#define B_VNDIRTY 0x02000000 /* On vnode dirty list */
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269#define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
270#define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */
271#define B_RAM 0x10000000 /* Read ahead mark (flag) */
272#define B_VMIO 0x20000000 /* VMIO flag */
273#define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
274#define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */
275
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276#define PRINT_BUF_FLAGS "\20" \
277 "\40nowdrain\37cluster\36vmio\35ram\34ordered" \
278 "\33paging\32vndirty\31vnclean\30want\27relbuf\26dirty" \
279 "\25unused20\24raw\23unused18\22clusterok\21malloc\20nocache" \
280 "\17locked\16inval\15unused12\14error\13eintr\12unused9\11unused8" \
281 "\10delwri\7hashed\6cache\5deferred\4direct\3async\2needcommit\1age"
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282
283#define NOOFFSET (-1LL) /* No buffer offset calculated yet */
284
285#ifdef _KERNEL
286/*
3020e3be 287 * Buffer locking. See sys/buf2.h for inline functions.
984263bc 288 */
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289extern char *buf_wmesg; /* Default buffer lock message */
290#define BUF_WMESG "bufwait"
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291
292#endif /* _KERNEL */
293
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294struct bio_queue_head {
295 TAILQ_HEAD(bio_queue, bio) queue;
54078292 296 off_t last_offset;
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297 struct bio *insert_point;
298 struct bio *switch_point;
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299};
300
301/*
54078292 302 * This structure describes a clustered I/O.
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303 */
304struct cluster_save {
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305 int bs_nchildren; /* Number of associated buffers. */
306 struct buf **bs_children; /* List of associated buffers. */
307};
308
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309/*
310 * Zero out the buffer's data area.
311 */
312#define clrbuf(bp) { \
313 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
314 (bp)->b_resid = 0; \
315}
316
317/*
318 * Flags to low-level bitmap allocation routines (balloc).
319 *
320 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count
321 * to 127.
322 */
323#define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */
324#define B_SEQSHIFT 24 /* Sequential heuristic shift. */
325#define B_SEQMAX 0x7F
326#define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */
327#define B_SYNC 0x02 /* Do all allocations synchronously. */
328
329#ifdef _KERNEL
330extern int nbuf; /* The number of buffer headers */
331extern int maxswzone; /* Max KVA for swap structures */
332extern int maxbcache; /* Max KVA for buffer cache */
333extern int runningbufspace;
334extern int buf_maxio; /* nominal maximum I/O for buffer */
41cbf46c 335extern struct buf *buf; /* The buffer headers. */
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336extern char *buffers; /* The buffer contents. */
337extern int bufpages; /* Number of memory pages in the buffer pool. */
338extern struct buf *swbuf; /* Swap I/O buffer headers. */
339extern int nswbuf; /* Number of swap I/O buffer headers. */
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340
341struct uio;
342
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343void bufinit (void);
344void bwillwrite (void);
345int buf_dirty_count_severe (void);
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346void initbufbio(struct buf *);
347void reinitbufbio(struct buf *);
348void clearbiocache(struct bio *);
b153f746 349void bremfree (struct buf *);
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350int bread (struct vnode *, off_t, int, struct buf **);
351int breadn (struct vnode *, off_t, int, off_t *, int *, int,
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352 struct buf **);
353int bwrite (struct buf *);
354void bdwrite (struct buf *);
355void bawrite (struct buf *);
356void bdirty (struct buf *);
357void bundirty (struct buf *);
358int bowrite (struct buf *);
359void brelse (struct buf *);
360void bqrelse (struct buf *);
361int vfs_bio_awrite (struct buf *);
81b5c339 362struct buf *getpbuf (int *);
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363int inmem (struct vnode *, off_t);
364struct buf *findblk (struct vnode *, off_t);
365struct buf *getblk (struct vnode *, off_t, int, int, int);
b153f746 366struct buf *geteblk (int);
5e23ca53 367void regetblk(struct buf *bp);
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368struct bio *push_bio(struct bio *);
369void pop_bio(struct bio *);
b153f746 370int biowait (struct buf *);
81b5c339 371void biodone (struct bio *);
984263bc 372
81b5c339 373void cluster_append(struct bio *, struct buf *);
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374int cluster_read (struct vnode *, off_t, off_t, int,
375 int, int, struct buf **);
376int cluster_wbuild (struct vnode *, int, off_t, int);
377void cluster_write (struct buf *, off_t, int);
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378int physread (struct dev_read_args *);
379int physwrite (struct dev_write_args *);
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380void vfs_bio_set_validclean (struct buf *, int base, int size);
381void vfs_bio_clrbuf (struct buf *);
10f3fee5 382void vfs_busy_pages (struct vnode *, struct buf *);
b153f746 383void vfs_unbusy_pages (struct buf *);
3591bbc6 384int vmapbuf (struct buf *, caddr_t, int);
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385void vunmapbuf (struct buf *);
386void relpbuf (struct buf *, int *);
387void brelvp (struct buf *);
388void bgetvp (struct vnode *, struct buf *);
b153f746 389int allocbuf (struct buf *bp, int size);
41cbf46c 390int scan_all_buffers (int (*)(struct buf *, void *), void *);
1f1ea522 391void reassignbuf (struct buf *);
b153f746 392struct buf *trypbuf (int *);
408357d8 393void bio_ops_sync(struct mount *mp);
984263bc 394
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395#endif /* _KERNEL */
396#endif /* _KERNEL || _KERNEL_STRUCTURES */
397#endif /* !_SYS_BUF_H_ */