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1.1 root 1: /*
2: * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. All advertising materials mentioning features or use of this software
14: * must display the following acknowledgement:
15: * This product includes software developed by the University of
16: * California, Berkeley and its contributors.
17: * 4. Neither the name of the University nor the names of its contributors
18: * may be used to endorse or promote products derived from this software
19: * without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31: * SUCH DAMAGE.
32: *
33: * @(#)buf.h 7.11 (Berkeley) 5/9/90
1.1.1.2 ! root 34: *
! 35: * PATCHES MAGIC LEVEL PATCH THAT GOT US HERE
! 36: * -------------------- ----- ----------------------
! 37: * CURRENT PATCH LEVEL: 1 00007
! 38: * -------------------- ----- ----------------------
! 39: *
! 40: * 20 Aug 92 David Greenman Fixed buffer cache hash index
! 41: * calculation
1.1 root 42: */
43:
44: /*
45: * The header for buffers in the buffer pool and otherwise used
46: * to describe a block i/o request is given here.
47: *
48: * Each buffer in the pool is usually doubly linked into 2 lists:
49: * hashed into a chain by <dev,blkno> so it can be located in the cache,
50: * and (usually) on (one of several) queues. These lists are circular and
51: * doubly linked for easy removal.
52: *
53: * There are currently three queues for buffers:
54: * one for buffers which must be kept permanently (super blocks)
55: * one for buffers containing ``useful'' information (the cache)
56: * one for buffers containing ``non-useful'' information
57: * (and empty buffers, pushed onto the front)
58: * The latter two queues contain the buffers which are available for
59: * reallocation, are kept in lru order. When not on one of these queues,
60: * the buffers are ``checked out'' to drivers which use the available list
61: * pointers to keep track of them in their i/o active queues.
62: */
63:
64: /*
65: * Bufhd structures used at the head of the hashed buffer queues.
66: * We only need three words for these, so this abbreviated
67: * definition saves some space.
68: */
69: struct bufhd
70: {
71: long b_flags; /* see defines below */
72: struct buf *b_forw, *b_back; /* fwd/bkwd pointer in chain */
73: };
74: struct buf
75: {
76: long b_flags; /* too much goes here to describe */
77: struct buf *b_forw, *b_back; /* hash chain (2 way street) */
78: struct buf *av_forw, *av_back; /* position on free list if not BUSY */
79: struct buf *b_blockf, **b_blockb;/* associated vnode */
80: #define b_actf av_forw /* alternate names for driver queue */
81: #define b_actl av_back /* head - isn't history wonderful */
82: long b_bcount; /* transfer count */
83: long b_bufsize; /* size of allocated buffer */
84: #define b_active b_bcount /* driver queue head: drive active */
85: short b_error; /* returned after I/O */
86: dev_t b_dev; /* major+minor device name */
87: union {
88: caddr_t b_addr; /* low order core address */
89: int *b_words; /* words for clearing */
90: struct fs *b_fs; /* superblocks */
91: struct csum *b_cs; /* superblock summary information */
92: struct cg *b_cg; /* cylinder group block */
93: struct dinode *b_dino; /* ilist */
94: daddr_t *b_daddr; /* indirect block */
95: } b_un;
96: daddr_t b_lblkno; /* logical block number */
97: daddr_t b_blkno; /* block # on device */
98: long b_resid; /* words not transferred after error */
99: #define b_errcnt b_resid /* while i/o in progress: # retries */
100: struct proc *b_proc; /* proc doing physical or swap I/O */
101: int (*b_iodone)(); /* function called by iodone */
102: struct vnode *b_vp; /* vnode for dev */
103: int b_pfcent; /* center page when swapping cluster */
104: struct ucred *b_rcred; /* ref to read credentials */
105: struct ucred *b_wcred; /* ref to write credendtials */
106: int b_dirtyoff; /* offset in buffer of dirty region */
107: int b_dirtyend; /* offset of end of dirty region */
108: caddr_t b_saveaddr; /* original b_addr for PHYSIO */
109: };
110:
111: #define BQUEUES 4 /* number of free buffer queues */
112:
113: #define BQ_LOCKED 0 /* super-blocks &c */
114: #define BQ_LRU 1 /* lru, useful buffers */
115: #define BQ_AGE 2 /* rubbish */
116: #define BQ_EMPTY 3 /* buffer headers with no memory */
117:
118: #ifdef KERNEL
119: #define BUFHSZ 512
120: #define RND (MAXBSIZE/DEV_BSIZE)
1.1.1.2 ! root 121: /* 20 Aug 92 BUFHASH*/
1.1 root 122: #if ((BUFHSZ&(BUFHSZ-1)) == 0)
123: #define BUFHASH(dvp, dblkno) \
1.1.1.2 ! root 124: ((struct buf *)&bufhash[((int)(dvp)/sizeof(struct vnode)+(int)(dblkno))&(BUFHSZ-1)])
1.1 root 125: #else
126: #define BUFHASH(dvp, dblkno) \
1.1.1.2 ! root 127: ((struct buf *)&bufhash[((int)(dvp)/sizeof(struct vnode)+(int)(dblkno)) % BUFHSZ])
1.1 root 128: #endif
129:
130: struct buf *buf; /* the buffer pool itself */
131: char *buffers;
132: int nbuf; /* number of buffer headers */
133: int bufpages; /* number of memory pages in the buffer pool */
134: struct buf *swbuf; /* swap I/O headers */
135: int nswbuf;
136: struct bufhd bufhash[BUFHSZ]; /* heads of hash lists */
137: struct buf bfreelist[BQUEUES]; /* heads of available lists */
138: struct buf bswlist; /* head of free swap header list */
139: struct buf *bclnlist; /* head of cleaned page list */
140:
1.1.1.2 ! root 141: void bufinit();
! 142: int bread(struct vnode *, daddr_t, int, struct ucred *, struct buf **);
! 143: int breada(struct vnode *, daddr_t, int, daddr_t, int, struct ucred *,
! 144: struct buf **);
! 145: int bwrite(struct buf *);
! 146: void bawrite(struct buf *);
! 147: void bdwrite(struct buf *);
! 148: void brelse(struct buf *);
! 149: struct buf *incore(struct vnode *, daddr_t);
! 150: struct buf *getblk(struct vnode *, daddr_t, int);
! 151: struct buf *geteblk(int);
! 152: int biowait(struct buf *);
! 153: int biodone(struct buf *);
! 154: void allocbuf(struct buf *, int);
1.1 root 155:
156: #endif
157:
158: /*
159: * These flags are kept in b_flags.
160: */
161: #define B_WRITE 0x000000 /* non-read pseudo-flag */
162: #define B_READ 0x000001 /* read when I/O occurs */
163: #define B_DONE 0x000002 /* transaction finished */
164: #define B_ERROR 0x000004 /* transaction aborted */
165: #define B_BUSY 0x000008 /* not on av_forw/back list */
166: #define B_PHYS 0x000010 /* physical IO */
167: #define B_XXX 0x000020 /* was B_MAP, alloc UNIBUS on pdp-11 */
168: #define B_WANTED 0x000040 /* issue wakeup when BUSY goes off */
169: #define B_AGE 0x000080 /* delayed write for correct aging */
170: #define B_ASYNC 0x000100 /* don't wait for I/O completion */
171: #define B_DELWRI 0x000200 /* write at exit of avail list */
172: #define B_TAPE 0x000400 /* this is a magtape (no bdwrite) */
1.1.1.2 ! root 173: #define B_VMPAGE 0x000800 /* buffer from virtual memory */
! 174: #define B_MALLOC 0x001000 /* buffer from malloc space */
1.1 root 175: #define B_DIRTY 0x002000 /* dirty page to be pushed out async */
176: #define B_PGIN 0x004000 /* pagein op, so swap() can count it */
177: #define B_CACHE 0x008000 /* did bread find us in the cache ? */
178: #define B_INVAL 0x010000 /* does not contain valid info */
179: #define B_LOCKED 0x020000 /* locked in core (not reusable) */
180: #define B_HEAD 0x040000 /* a buffer header, not a buffer */
181: #define B_BAD 0x100000 /* bad block revectoring in progress */
182: #define B_CALL 0x200000 /* call b_iodone from iodone */
183: #define B_RAW 0x400000 /* set by physio for raw transfers */
184: #define B_NOCACHE 0x800000 /* do not cache block after use */
185:
186: /*
187: * Insq/Remq for the buffer hash lists.
188: */
189: #define bremhash(bp) { \
190: (bp)->b_back->b_forw = (bp)->b_forw; \
191: (bp)->b_forw->b_back = (bp)->b_back; \
192: }
193: #define binshash(bp, dp) { \
194: (bp)->b_forw = (dp)->b_forw; \
195: (bp)->b_back = (dp); \
196: (dp)->b_forw->b_back = (bp); \
197: (dp)->b_forw = (bp); \
198: }
199:
200: /*
201: * Insq/Remq for the buffer free lists.
202: */
203: #define bremfree(bp) { \
204: (bp)->av_back->av_forw = (bp)->av_forw; \
205: (bp)->av_forw->av_back = (bp)->av_back; \
206: }
207: #define binsheadfree(bp, dp) { \
208: (dp)->av_forw->av_back = (bp); \
209: (bp)->av_forw = (dp)->av_forw; \
210: (dp)->av_forw = (bp); \
211: (bp)->av_back = (dp); \
212: }
213: #define binstailfree(bp, dp) { \
214: (dp)->av_back->av_forw = (bp); \
215: (bp)->av_back = (dp)->av_back; \
216: (dp)->av_back = (bp); \
217: (bp)->av_forw = (dp); \
218: }
219:
220: #define iodone biodone
221: #define iowait biowait
222:
223: /*
224: * Zero out a buffer's data portion.
225: */
226: #define clrbuf(bp) { \
1.1.1.2 ! root 227: bzero((bp)->b_un.b_addr, (unsigned)(bp)->b_bcount); \
1.1 root 228: (bp)->b_resid = 0; \
229: }
230: #define B_CLRBUF 0x1 /* request allocated buffer be cleared */
231: #define B_SYNC 0x2 /* do all allocations synchronously */
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