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
|
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License v.2.
*/
/*
* These routines are used by the resource group routines (rgrp.c)
* to keep track of block allocation. Each block is represented by two
* bits. One bit indicates whether or not the block is used. (1=used,
* 0=free) The other bit indicates whether or not the block contains a
* dinode or not. (1=dinode, 0=not-dinode) So, each byte represents
* GFS2_NBBY (i.e. 4) blocks.
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/gfs2_ondisk.h>
#include <asm/semaphore.h>
#include "gfs2.h"
#include "lm_interface.h"
#include "incore.h"
#include "bits.h"
#include "util.h"
static const char valid_change[16] = {
/* current */
/* n */ 0, 1, 0, 1,
/* e */ 1, 0, 0, 0,
/* w */ 0, 0, 0, 0,
1, 0, 0, 0
};
/**
* gfs2_setbit - Set a bit in the bitmaps
* @buffer: the buffer that holds the bitmaps
* @buflen: the length (in bytes) of the buffer
* @block: the block to set
* @new_state: the new state of the block
*
*/
void gfs2_setbit(struct gfs2_rgrpd *rgd, unsigned char *buffer,
unsigned int buflen, uint32_t block, unsigned char new_state)
{
unsigned char *byte, *end, cur_state;
unsigned int bit;
byte = buffer + (block / GFS2_NBBY);
bit = (block % GFS2_NBBY) * GFS2_BIT_SIZE;
end = buffer + buflen;
gfs2_assert(rgd->rd_sbd, byte < end);
cur_state = (*byte >> bit) & GFS2_BIT_MASK;
if (valid_change[new_state * 4 + cur_state]) {
*byte ^= cur_state << bit;
*byte |= new_state << bit;
} else
gfs2_consist_rgrpd(rgd);
}
/**
* gfs2_testbit - test a bit in the bitmaps
* @buffer: the buffer that holds the bitmaps
* @buflen: the length (in bytes) of the buffer
* @block: the block to read
*
*/
unsigned char gfs2_testbit(struct gfs2_rgrpd *rgd, unsigned char *buffer,
unsigned int buflen, uint32_t block)
{
unsigned char *byte, *end, cur_state;
unsigned int bit;
byte = buffer + (block / GFS2_NBBY);
bit = (block % GFS2_NBBY) * GFS2_BIT_SIZE;
end = buffer + buflen;
gfs2_assert(rgd->rd_sbd, byte < end);
cur_state = (*byte >> bit) & GFS2_BIT_MASK;
return cur_state;
}
/**
* gfs2_bitfit - Search an rgrp's bitmap buffer to find a bit-pair representing
* a block in a given allocation state.
* @buffer: the buffer that holds the bitmaps
* @buflen: the length (in bytes) of the buffer
* @goal: start search at this block's bit-pair (within @buffer)
* @old_state: GFS2_BLKST_XXX the state of the block we're looking for;
* bit 0 = alloc(1)/free(0), bit 1 = meta(1)/data(0)
*
* Scope of @goal and returned block number is only within this bitmap buffer,
* not entire rgrp or filesystem. @buffer will be offset from the actual
* beginning of a bitmap block buffer, skipping any header structures.
*
* Return: the block number (bitmap buffer scope) that was found
*/
uint32_t gfs2_bitfit(struct gfs2_rgrpd *rgd, unsigned char *buffer,
unsigned int buflen, uint32_t goal,
unsigned char old_state)
{
unsigned char *byte, *end, alloc;
uint32_t blk = goal;
unsigned int bit;
byte = buffer + (goal / GFS2_NBBY);
bit = (goal % GFS2_NBBY) * GFS2_BIT_SIZE;
end = buffer + buflen;
alloc = (old_state & 1) ? 0 : 0x55;
while (byte < end) {
if ((*byte & 0x55) == alloc) {
blk += (8 - bit) >> 1;
bit = 0;
byte++;
continue;
}
if (((*byte >> bit) & GFS2_BIT_MASK) == old_state)
return blk;
bit += GFS2_BIT_SIZE;
if (bit >= 8) {
bit = 0;
byte++;
}
blk++;
}
return BFITNOENT;
}
/**
* gfs2_bitcount - count the number of bits in a certain state
* @buffer: the buffer that holds the bitmaps
* @buflen: the length (in bytes) of the buffer
* @state: the state of the block we're looking for
*
* Returns: The number of bits
*/
uint32_t gfs2_bitcount(struct gfs2_rgrpd *rgd, unsigned char *buffer,
unsigned int buflen, unsigned char state)
{
unsigned char *byte = buffer;
unsigned char *end = buffer + buflen;
unsigned char state1 = state << 2;
unsigned char state2 = state << 4;
unsigned char state3 = state << 6;
uint32_t count = 0;
for (; byte < end; byte++) {
if (((*byte) & 0x03) == state)
count++;
if (((*byte) & 0x0C) == state1)
count++;
if (((*byte) & 0x30) == state2)
count++;
if (((*byte) & 0xC0) == state3)
count++;
}
return count;
}
|
