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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
34: */
35:
36: /*
37: * The header for buffers in the buffer pool and otherwise used
38: * to describe a block i/o request is given here.
39: *
40: * Each buffer in the pool is usually doubly linked into 2 lists:
41: * hashed into a chain by <dev,blkno> so it can be located in the cache,
42: * and (usually) on (one of several) queues. These lists are circular and
43: * doubly linked for easy removal.
44: *
45: * There are currently three queues for buffers:
46: * one for buffers which must be kept permanently (super blocks)
47: * one for buffers containing ``useful'' information (the cache)
48: * one for buffers containing ``non-useful'' information
49: * (and empty buffers, pushed onto the front)
50: * The latter two queues contain the buffers which are available for
51: * reallocation, are kept in lru order. When not on one of these queues,
52: * the buffers are ``checked out'' to drivers which use the available list
53: * pointers to keep track of them in their i/o active queues.
54: */
55:
56: /*
57: * Bufhd structures used at the head of the hashed buffer queues.
58: * We only need three words for these, so this abbreviated
59: * definition saves some space.
60: */
61: struct bufhd
62: {
63: long b_flags; /* see defines below */
64: struct buf *b_forw, *b_back; /* fwd/bkwd pointer in chain */
65: };
66: struct buf
67: {
68: long b_flags; /* too much goes here to describe */
69: struct buf *b_forw, *b_back; /* hash chain (2 way street) */
70: struct buf *av_forw, *av_back; /* position on free list if not BUSY */
71: struct buf *b_blockf, **b_blockb;/* associated vnode */
72: #define b_actf av_forw /* alternate names for driver queue */
73: #define b_actl av_back /* head - isn't history wonderful */
74: long b_bcount; /* transfer count */
75: long b_bufsize; /* size of allocated buffer */
76: #define b_active b_bcount /* driver queue head: drive active */
77: short b_error; /* returned after I/O */
78: dev_t b_dev; /* major+minor device name */
79: union {
80: caddr_t b_addr; /* low order core address */
81: int *b_words; /* words for clearing */
82: struct fs *b_fs; /* superblocks */
83: struct csum *b_cs; /* superblock summary information */
84: struct cg *b_cg; /* cylinder group block */
85: struct dinode *b_dino; /* ilist */
86: daddr_t *b_daddr; /* indirect block */
87: } b_un;
88: daddr_t b_lblkno; /* logical block number */
89: daddr_t b_blkno; /* block # on device */
90: long b_resid; /* words not transferred after error */
91: #define b_errcnt b_resid /* while i/o in progress: # retries */
92: struct proc *b_proc; /* proc doing physical or swap I/O */
93: int (*b_iodone)(); /* function called by iodone */
94: struct vnode *b_vp; /* vnode for dev */
95: int b_pfcent; /* center page when swapping cluster */
96: struct ucred *b_rcred; /* ref to read credentials */
97: struct ucred *b_wcred; /* ref to write credendtials */
98: int b_dirtyoff; /* offset in buffer of dirty region */
99: int b_dirtyend; /* offset of end of dirty region */
100: caddr_t b_saveaddr; /* original b_addr for PHYSIO */
101: };
102:
103: #define BQUEUES 4 /* number of free buffer queues */
104:
105: #define BQ_LOCKED 0 /* super-blocks &c */
106: #define BQ_LRU 1 /* lru, useful buffers */
107: #define BQ_AGE 2 /* rubbish */
108: #define BQ_EMPTY 3 /* buffer headers with no memory */
109:
110: #ifdef KERNEL
111: #define BUFHSZ 512
112: #define RND (MAXBSIZE/DEV_BSIZE)
113: #if ((BUFHSZ&(BUFHSZ-1)) == 0)
114: #define BUFHASH(dvp, dblkno) \
115: ((struct buf *)&bufhash[((int)(dvp)+(((int)(dblkno))/RND))&(BUFHSZ-1)])
116: #else
117: #define BUFHASH(dvp, dblkno) \
118: ((struct buf *)&bufhash[((int)(dvp)+(((int)(dblkno))/RND)) % BUFHSZ])
119: #endif
120:
121: struct buf *buf; /* the buffer pool itself */
122: char *buffers;
123: int nbuf; /* number of buffer headers */
124: int bufpages; /* number of memory pages in the buffer pool */
125: struct buf *swbuf; /* swap I/O headers */
126: int nswbuf;
127: struct bufhd bufhash[BUFHSZ]; /* heads of hash lists */
128: struct buf bfreelist[BQUEUES]; /* heads of available lists */
129: struct buf bswlist; /* head of free swap header list */
130: struct buf *bclnlist; /* head of cleaned page list */
131:
132: struct buf *getblk();
133: struct buf *geteblk();
134: struct buf *getnewbuf();
135:
136: unsigned minphys();
137: #endif
138:
139: /*
140: * These flags are kept in b_flags.
141: */
142: #define B_WRITE 0x000000 /* non-read pseudo-flag */
143: #define B_READ 0x000001 /* read when I/O occurs */
144: #define B_DONE 0x000002 /* transaction finished */
145: #define B_ERROR 0x000004 /* transaction aborted */
146: #define B_BUSY 0x000008 /* not on av_forw/back list */
147: #define B_PHYS 0x000010 /* physical IO */
148: #define B_XXX 0x000020 /* was B_MAP, alloc UNIBUS on pdp-11 */
149: #define B_WANTED 0x000040 /* issue wakeup when BUSY goes off */
150: #define B_AGE 0x000080 /* delayed write for correct aging */
151: #define B_ASYNC 0x000100 /* don't wait for I/O completion */
152: #define B_DELWRI 0x000200 /* write at exit of avail list */
153: #define B_TAPE 0x000400 /* this is a magtape (no bdwrite) */
154: #define B_UAREA 0x000800 /* add u-area to a swap operation */
155: #define B_PAGET 0x001000 /* page in/out of page table space */
156: #define B_DIRTY 0x002000 /* dirty page to be pushed out async */
157: #define B_PGIN 0x004000 /* pagein op, so swap() can count it */
158: #define B_CACHE 0x008000 /* did bread find us in the cache ? */
159: #define B_INVAL 0x010000 /* does not contain valid info */
160: #define B_LOCKED 0x020000 /* locked in core (not reusable) */
161: #define B_HEAD 0x040000 /* a buffer header, not a buffer */
162: #define B_BAD 0x100000 /* bad block revectoring in progress */
163: #define B_CALL 0x200000 /* call b_iodone from iodone */
164: #define B_RAW 0x400000 /* set by physio for raw transfers */
165: #define B_NOCACHE 0x800000 /* do not cache block after use */
166:
167: /*
168: * Insq/Remq for the buffer hash lists.
169: */
170: #define bremhash(bp) { \
171: (bp)->b_back->b_forw = (bp)->b_forw; \
172: (bp)->b_forw->b_back = (bp)->b_back; \
173: }
174: #define binshash(bp, dp) { \
175: (bp)->b_forw = (dp)->b_forw; \
176: (bp)->b_back = (dp); \
177: (dp)->b_forw->b_back = (bp); \
178: (dp)->b_forw = (bp); \
179: }
180:
181: /*
182: * Insq/Remq for the buffer free lists.
183: */
184: #define bremfree(bp) { \
185: (bp)->av_back->av_forw = (bp)->av_forw; \
186: (bp)->av_forw->av_back = (bp)->av_back; \
187: }
188: #define binsheadfree(bp, dp) { \
189: (dp)->av_forw->av_back = (bp); \
190: (bp)->av_forw = (dp)->av_forw; \
191: (dp)->av_forw = (bp); \
192: (bp)->av_back = (dp); \
193: }
194: #define binstailfree(bp, dp) { \
195: (dp)->av_back->av_forw = (bp); \
196: (bp)->av_back = (dp)->av_back; \
197: (dp)->av_back = (bp); \
198: (bp)->av_forw = (dp); \
199: }
200:
201: #define iodone biodone
202: #define iowait biowait
203:
204: /*
205: * Zero out a buffer's data portion.
206: */
207: #define clrbuf(bp) { \
208: blkclr((bp)->b_un.b_addr, (unsigned)(bp)->b_bcount); \
209: (bp)->b_resid = 0; \
210: }
211: #define B_CLRBUF 0x1 /* request allocated buffer be cleared */
212: #define B_SYNC 0x2 /* do all allocations synchronously */
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