Document the handling of a file holes in ufs_strategy() and clean up
[dragonfly.git] / sys / sys / buf.h
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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 $
3591bbc6 40 * $DragonFly: src/sys/sys/buf.h,v 1.33 2006/04/30 20:23:25 dillon Exp $
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41 */
42
43#ifndef _SYS_BUF_H_
44#define _SYS_BUF_H_
45
335dda38 46#ifndef _SYS_QUEUE_H_
984263bc 47#include <sys/queue.h>
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48#endif
49#ifndef _SYS_LOCK_H_
984263bc 50#include <sys/lock.h>
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51#endif
52#ifndef _SYS_DEVICE_H_
53#include <sys/device.h>
54#endif
984263bc 55
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56#ifndef _SYS_XIO_H_
57#include <sys/xio.h>
58#endif
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59#ifndef _SYS_TREE_H_
60#include <sys/tree.h>
61#endif
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62#ifndef _SYS_BIO_H_
63#include <sys/bio.h>
64#endif
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65#ifndef _SYS_SPINLOCK_H_
66#include <sys/spinlock.h>
67#endif
1eabbf32 68
984263bc 69struct buf;
81b5c339 70struct bio;
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71struct mount;
72struct vnode;
54f51aeb 73struct xio;
984263bc 74
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75#define NBUF_BIO 4
76
6bae6177 77struct buf_rb_tree;
1f1ea522 78struct buf_rb_hash;
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79RB_PROTOTYPE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, off_t);
80RB_PROTOTYPE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, off_t);
6bae6177 81
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82/*
83 * To avoid including <ufs/ffs/softdep.h>
84 */
85LIST_HEAD(workhead, worklist);
86/*
87 * These are currently used only by the soft dependency code, hence
88 * are stored once in a global variable. If other subsystems wanted
89 * to use these hooks, a pointer to a set of bio_ops could be added
90 * to each buffer.
91 */
92extern struct bio_ops {
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93 void (*io_start) (struct buf *);
94 void (*io_complete) (struct buf *);
95 void (*io_deallocate) (struct buf *);
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96 int (*io_fsync) (struct vnode *);
97 int (*io_sync) (struct mount *);
b153f746 98 void (*io_movedeps) (struct buf *, struct buf *);
1e5a0c40 99 int (*io_countdeps) (struct buf *, int);
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100} bioops;
101
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102typedef enum buf_cmd {
103 BUF_CMD_DONE = 0,
104 BUF_CMD_READ,
105 BUF_CMD_WRITE,
106 BUF_CMD_FREEBLKS,
107 BUF_CMD_FORMAT
108} buf_cmd_t;
109
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110/*
111 * The buffer header describes an I/O operation in the kernel.
112 *
113 * NOTES:
114 * b_bufsize, b_bcount. b_bufsize is the allocation size of the
115 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
116 * originally requested buffer size and can serve as a bounds check
117 * against EOF. For most, but not all uses, b_bcount == b_bufsize.
118 *
119 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
120 * ranges of dirty data that need to be written to backing store.
121 * The range is typically clipped at b_bcount ( not b_bufsize ).
122 *
123 * b_resid. Number of bytes remaining in I/O. After an I/O operation
124 * completes, b_resid is usually 0 indicating 100% success.
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125 *
126 * b_bio1 and b_bio2 represent the two primary I/O layers. Additional
127 * I/O layers are allocated out of the object cache and may also exist.
128 *
129 * b_bio1 is the logical layer and contains offset or block number
130 * data for the primary vnode, b_vp. I/O operations are almost
131 * universally initiated from the logical layer, so you will often
132 * see things like: vn_strategy(bp->b_vp, &bp->b_bio1).
133 *
134 * b_bio2 is the first physical layer (typically the slice-relative
135 * layer) and contains the translated offset or block number for
136 * the block device underlying a filesystem. Filesystems such as UFS
137 * will maintain cached translations and you may see them initiate
138 * a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2). BUT,
139 * remember that the layering is relative to bp->b_vp, so the
140 * device-relative block numbers for buffer cache operations that occur
141 * directly on a block device will be in the first BIO layer.
142 *
143 * NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly.
144 * ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO
145 * PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE
146 * I/O DEEPER. In particular, a vn_strategy() or dev_dstrategy()
147 * call should not ever access buf->b_vp as this vnode may be totally
148 * unrelated to the vnode/device whos strategy routine was called.
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149 */
150struct buf {
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151 RB_ENTRY(buf) b_rbnode; /* RB node in vnode clean/dirty tree */
152 RB_ENTRY(buf) b_rbhash; /* RB node in vnode hash tree */
984263bc 153 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
81b5c339 154 struct buf *b_cluster_next; /* Next buffer (cluster code) */
54078292 155 struct vnode *b_vp; /* (vp, loffset) index */
81b5c339 156 struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */
54078292 157 u_int32_t b_flags; /* B_* flags. */
984263bc 158 unsigned short b_qindex; /* buffer queue index */
9e45bec7 159 unsigned short b_unused01;
984263bc 160 struct lock b_lock; /* Buffer lock */
10f3fee5 161 buf_cmd_t b_cmd; /* I/O command */
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162 int b_bufsize; /* Allocated buffer size. */
163 int b_runningbufspace; /* when I/O is running, pipelining */
164 int b_bcount; /* Valid bytes in buffer. */
165 int b_resid; /* Remaining I/O */
81b5c339 166 int b_error; /* Error return */
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167 caddr_t b_data; /* Memory, superblocks, indirect etc. */
168 caddr_t b_kvabase; /* base kva for buffer */
169 int b_kvasize; /* size of kva for buffer */
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170 int b_dirtyoff; /* Offset in buffer of dirty region. */
171 int b_dirtyend; /* Offset of end of dirty region. */
81b5c339 172 struct xio b_xio; /* data buffer page list management */
984263bc 173 struct workhead b_dep; /* List of filesystem dependencies. */
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174};
175
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176/*
177 * XXX temporary
178 */
179#define b_bio1 b_bio_array[0] /* logical layer */
180#define b_bio2 b_bio_array[1] /* (typically) the disk layer */
181#define b_loffset b_bio1.bio_offset
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182
183/*
184 * These flags are kept in b_flags.
185 *
186 * Notes:
187 *
188 * B_ASYNC VOP calls on bp's are usually async whether or not
189 * B_ASYNC is set, but some subsystems, such as NFS, like
190 * to know what is best for the caller so they can
191 * optimize the I/O.
192 *
193 * B_PAGING Indicates that bp is being used by the paging system or
194 * some paging system and that the bp is not linked into
195 * the b_vp's clean/dirty linked lists or ref counts.
196 * Buffer vp reassignments are illegal in this case.
197 *
198 * B_CACHE This may only be set if the buffer is entirely valid.
199 * The situation where B_DELWRI is set and B_CACHE is
200 * clear MUST be committed to disk by getblk() so
201 * B_DELWRI can also be cleared. See the comments for
202 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
203 * the caller is expected to clear B_ERROR|B_INVAL,
10f3fee5 204 * set BUF_CMD_READ, and initiate an I/O.
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205 *
206 * The 'entire buffer' is defined to be the range from
207 * 0 through b_bcount.
208 *
209 * B_MALLOC Request that the buffer be allocated from the malloc
210 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
211 *
212 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
213 * by filesystems that allow clustering when the buffer
214 * is fully dirty and indicates that it may be clustered
215 * with other adjacent dirty buffers. Note the clustering
216 * may not be used with the stage 1 data write under NFS
217 * but may be used for the commit rpc portion.
218 *
219 * B_VMIO Indicates that the buffer is tied into an VM object.
220 * The buffer's data is always PAGE_SIZE aligned even
221 * if b_bufsize and b_bcount are not. ( b_bufsize is
222 * always at least DEV_BSIZE aligned, though ).
223 *
224 * B_DIRECT Hint that we should attempt to completely free
225 * the pages underlying the buffer. B_DIRECT is
226 * sticky until the buffer is released and typically
227 * only has an effect when B_RELBUF is also set.
228 *
229 * B_NOWDRAIN This flag should be set when a device (like VN)
230 * does a turn-around VOP_WRITE from its strategy
231 * routine. This flag prevents bwrite() from blocking
232 * in wdrain, avoiding a deadlock situation.
233 */
234
235#define B_AGE 0x00000001 /* Move to age queue when I/O done. */
236#define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
237#define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
238#define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
239#define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
240#define B_CACHE 0x00000020 /* Bread found us in the cache. */
1f1ea522 241#define B_HASHED 0x00000040 /* Indexed via v_rbhash_tree */
984263bc 242#define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
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243#define B_UNUSED0100 0x00000100
244#define B_UNUSED0200 0x00000200
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245#define B_EINTR 0x00000400 /* I/O was interrupted */
246#define B_ERROR 0x00000800 /* I/O error occurred. */
71bc1d95 247#define B_UNUSED1000 0x00001000 /* Unused */
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248#define B_INVAL 0x00002000 /* Does not contain valid info. */
249#define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
250#define B_NOCACHE 0x00008000 /* Do not cache block after use. */
251#define B_MALLOC 0x00010000 /* malloced b_data */
252#define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
9fd739f4 253#define B_UNUSED40000 0x00040000
984263bc 254#define B_RAW 0x00080000 /* Set by physio for raw transfers. */
9e45bec7 255#define B_UNUSED100000 0x00100000
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256#define B_DIRTY 0x00200000 /* Needs writing later. */
257#define B_RELBUF 0x00400000 /* Release VMIO buffer. */
258#define B_WANT 0x00800000 /* Used by vm_pager.c */
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259#define B_VNCLEAN 0x01000000 /* On vnode clean list */
260#define B_VNDIRTY 0x02000000 /* On vnode dirty list */
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261#define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
262#define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */
263#define B_RAM 0x10000000 /* Read ahead mark (flag) */
264#define B_VMIO 0x20000000 /* VMIO flag */
265#define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
266#define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */
267
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268#define PRINT_BUF_FLAGS "\20" \
269 "\40nowdrain\37cluster\36vmio\35ram\34ordered" \
270 "\33paging\32vndirty\31vnclean\30want\27relbuf\26dirty" \
271 "\25unused20\24raw\23unused18\22clusterok\21malloc\20nocache" \
272 "\17locked\16inval\15unused12\14error\13eintr\12unused9\11unused8" \
273 "\10delwri\7hashed\6cache\5deferred\4direct\3async\2needcommit\1age"
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274
275#define NOOFFSET (-1LL) /* No buffer offset calculated yet */
276
277#ifdef _KERNEL
278/*
3020e3be 279 * Buffer locking. See sys/buf2.h for inline functions.
984263bc 280 */
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281extern char *buf_wmesg; /* Default buffer lock message */
282#define BUF_WMESG "bufwait"
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283
284#endif /* _KERNEL */
285
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286struct bio_queue_head {
287 TAILQ_HEAD(bio_queue, bio) queue;
54078292 288 off_t last_offset;
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289 struct bio *insert_point;
290 struct bio *switch_point;
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291};
292
293/*
54078292 294 * This structure describes a clustered I/O.
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295 */
296struct cluster_save {
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297 int bs_nchildren; /* Number of associated buffers. */
298 struct buf **bs_children; /* List of associated buffers. */
299};
300
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301/*
302 * Zero out the buffer's data area.
303 */
304#define clrbuf(bp) { \
305 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
306 (bp)->b_resid = 0; \
307}
308
309/*
310 * Flags to low-level bitmap allocation routines (balloc).
311 *
312 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count
313 * to 127.
314 */
315#define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */
316#define B_SEQSHIFT 24 /* Sequential heuristic shift. */
317#define B_SEQMAX 0x7F
318#define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */
319#define B_SYNC 0x02 /* Do all allocations synchronously. */
320
321#ifdef _KERNEL
322extern int nbuf; /* The number of buffer headers */
323extern int maxswzone; /* Max KVA for swap structures */
324extern int maxbcache; /* Max KVA for buffer cache */
325extern int runningbufspace;
326extern int buf_maxio; /* nominal maximum I/O for buffer */
41cbf46c 327extern struct buf *buf; /* The buffer headers. */
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328extern char *buffers; /* The buffer contents. */
329extern int bufpages; /* Number of memory pages in the buffer pool. */
330extern struct buf *swbuf; /* Swap I/O buffer headers. */
331extern int nswbuf; /* Number of swap I/O buffer headers. */
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332
333struct uio;
334
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335void bufinit (void);
336void bwillwrite (void);
337int buf_dirty_count_severe (void);
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338void initbufbio(struct buf *);
339void reinitbufbio(struct buf *);
340void clearbiocache(struct bio *);
b153f746 341void bremfree (struct buf *);
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342int bread (struct vnode *, off_t, int, struct buf **);
343int breadn (struct vnode *, off_t, int, off_t *, int *, int,
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344 struct buf **);
345int bwrite (struct buf *);
346void bdwrite (struct buf *);
347void bawrite (struct buf *);
348void bdirty (struct buf *);
349void bundirty (struct buf *);
350int bowrite (struct buf *);
351void brelse (struct buf *);
352void bqrelse (struct buf *);
353int vfs_bio_awrite (struct buf *);
81b5c339 354struct buf *getpbuf (int *);
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355int inmem (struct vnode *, off_t);
356struct buf *findblk (struct vnode *, off_t);
357struct buf *getblk (struct vnode *, off_t, int, int, int);
b153f746 358struct buf *geteblk (int);
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359struct bio *push_bio(struct bio *);
360void pop_bio(struct bio *);
b153f746 361int biowait (struct buf *);
81b5c339 362void biodone (struct bio *);
984263bc 363
81b5c339 364void cluster_append(struct bio *, struct buf *);
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365int cluster_read (struct vnode *, off_t, off_t, int,
366 int, int, struct buf **);
367int cluster_wbuild (struct vnode *, int, off_t, int);
368void cluster_write (struct buf *, off_t, int);
b153f746 369int physio (dev_t dev, struct uio *uio, int ioflag);
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370#define physread physio
371#define physwrite physio
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372void vfs_bio_set_validclean (struct buf *, int base, int size);
373void vfs_bio_clrbuf (struct buf *);
10f3fee5 374void vfs_busy_pages (struct vnode *, struct buf *);
b153f746 375void vfs_unbusy_pages (struct buf *);
3591bbc6 376int vmapbuf (struct buf *, caddr_t, int);
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377void vunmapbuf (struct buf *);
378void relpbuf (struct buf *, int *);
379void brelvp (struct buf *);
380void bgetvp (struct vnode *, struct buf *);
b153f746 381int allocbuf (struct buf *bp, int size);
41cbf46c 382int scan_all_buffers (int (*)(struct buf *, void *), void *);
1f1ea522 383void reassignbuf (struct buf *);
b153f746 384struct buf *trypbuf (int *);
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385
386#endif /* _KERNEL */
387
388#endif /* !_SYS_BUF_H_ */