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
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/*
* linux/fs/sysv/balloc.c
*
* minix/bitmap.c
* Copyright (C) 1991, 1992 Linus Torvalds
*
* ext/freelists.c
* Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
*
* xenix/alloc.c
* Copyright (C) 1992 Doug Evans
*
* coh/alloc.c
* Copyright (C) 1993 Pascal Haible, Bruno Haible
*
* sysv/balloc.c
* Copyright (C) 1993 Bruno Haible
*
* This file contains code for allocating/freeing blocks.
*/
#include <linux/buffer_head.h>
#include <linux/string.h>
#include "sysv.h"
/* We don't trust the value of
sb->sv_sbd2->s_tfree = *sb->sv_free_blocks
but we nevertheless keep it up to date. */
static inline sysv_zone_t *get_chunk(struct super_block *sb, struct buffer_head *bh)
{
char *bh_data = bh->b_data;
if (SYSV_SB(sb)->s_type == FSTYPE_SYSV4)
return (sysv_zone_t*)(bh_data+4);
else
return (sysv_zone_t*)(bh_data+2);
}
/* NOTE NOTE NOTE: nr is a block number _as_ _stored_ _on_ _disk_ */
void sysv_free_block(struct super_block * sb, sysv_zone_t nr)
{
struct sysv_sb_info * sbi = SYSV_SB(sb);
struct buffer_head * bh;
sysv_zone_t *blocks = sbi->s_bcache;
unsigned count;
unsigned block = fs32_to_cpu(sbi, nr);
/*
* This code does not work at all for AFS (it has a bitmap
* free list). As AFS is supposed to be read-only no one
* should call this for an AFS filesystem anyway...
*/
if (sbi->s_type == FSTYPE_AFS)
return;
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
printk("sysv_free_block: trying to free block not in datazone\n");
return;
}
mutex_lock(&sbi->s_lock);
count = fs16_to_cpu(sbi, *sbi->s_bcache_count);
if (count > sbi->s_flc_size) {
printk("sysv_free_block: flc_count > flc_size\n");
mutex_unlock(&sbi->s_lock);
return;
}
/* If the free list head in super-block is full, it is copied
* into this block being freed, ditto if it's completely empty
* (applies only on Coherent).
*/
if (count == sbi->s_flc_size || count == 0) {
block += sbi->s_block_base;
bh = sb_getblk(sb, block);
if (!bh) {
printk("sysv_free_block: getblk() failed\n");
mutex_unlock(&sbi->s_lock);
return;
}
memset(bh->b_data, 0, sb->s_blocksize);
*(__fs16*)bh->b_data = cpu_to_fs16(sbi, count);
memcpy(get_chunk(sb,bh), blocks, count * sizeof(sysv_zone_t));
mark_buffer_dirty(bh);
set_buffer_uptodate(bh);
brelse(bh);
count = 0;
}
sbi->s_bcache[count++] = nr;
*sbi->s_bcache_count = cpu_to_fs16(sbi, count);
fs32_add(sbi, sbi->s_free_blocks, 1);
dirty_sb(sb);
mutex_unlock(&sbi->s_lock);
}
sysv_zone_t sysv_new_block(struct super_block * sb)
{
struct sysv_sb_info *sbi = SYSV_SB(sb);
unsigned int block;
sysv_zone_t nr;
struct buffer_head * bh;
unsigned count;
mutex_lock(&sbi->s_lock);
count = fs16_to_cpu(sbi, *sbi->s_bcache_count);
if (count == 0) /* Applies only to Coherent FS */
goto Enospc;
nr = sbi->s_bcache[--count];
if (nr == 0) /* Applies only to Xenix FS, SystemV FS */
goto Enospc;
block = fs32_to_cpu(sbi, nr);
*sbi->s_bcache_count = cpu_to_fs16(sbi, count);
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
printk("sysv_new_block: new block %d is not in data zone\n",
block);
goto Enospc;
}
if (count == 0) { /* the last block continues the free list */
unsigned count;
block += sbi->s_block_base;
if (!(bh = sb_bread(sb, block))) {
printk("sysv_new_block: cannot read free-list block\n");
/* retry this same block next time */
*sbi->s_bcache_count = cpu_to_fs16(sbi, 1);
goto Enospc;
}
count = fs16_to_cpu(sbi, *(__fs16*)bh->b_data);
if (count > sbi->s_flc_size) {
printk("sysv_new_block: free-list block with >flc_size entries\n");
brelse(bh);
goto Enospc;
}
*sbi->s_bcache_count = cpu_to_fs16(sbi, count);
memcpy(sbi->s_bcache, get_chunk(sb, bh),
count * sizeof(sysv_zone_t));
brelse(bh);
}
/* Now the free list head in the superblock is valid again. */
fs32_add(sbi, sbi->s_free_blocks, -1);
dirty_sb(sb);
mutex_unlock(&sbi->s_lock);
return nr;
Enospc:
mutex_unlock(&sbi->s_lock);
return 0;
}
unsigned long sysv_count_free_blocks(struct super_block * sb)
{
struct sysv_sb_info * sbi = SYSV_SB(sb);
int sb_count;
int count;
struct buffer_head * bh = NULL;
sysv_zone_t *blocks;
unsigned block;
int n;
/*
* This code does not work at all for AFS (it has a bitmap
* free list). As AFS is supposed to be read-only we just
* lie and say it has no free block at all.
*/
if (sbi->s_type == FSTYPE_AFS)
return 0;
mutex_lock(&sbi->s_lock);
sb_count = fs32_to_cpu(sbi, *sbi->s_free_blocks);
if (0)
goto trust_sb;
/* this causes a lot of disk traffic ... */
count = 0;
n = fs16_to_cpu(sbi, *sbi->s_bcache_count);
blocks = sbi->s_bcache;
while (1) {
sysv_zone_t zone;
if (n > sbi->s_flc_size)
goto E2big;
zone = 0;
while (n && (zone = blocks[--n]) != 0)
count++;
if (zone == 0)
break;
block = fs32_to_cpu(sbi, zone);
if (bh)
brelse(bh);
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones)
goto Einval;
block += sbi->s_block_base;
bh = sb_bread(sb, block);
if (!bh)
goto Eio;
n = fs16_to_cpu(sbi, *(__fs16*)bh->b_data);
blocks = get_chunk(sb, bh);
}
if (bh)
brelse(bh);
if (count != sb_count)
goto Ecount;
done:
mutex_unlock(&sbi->s_lock);
return count;
Einval:
printk("sysv_count_free_blocks: new block %d is not in data zone\n",
block);
goto trust_sb;
Eio:
printk("sysv_count_free_blocks: cannot read free-list block\n");
goto trust_sb;
E2big:
printk("sysv_count_free_blocks: >flc_size entries in free-list block\n");
if (bh)
brelse(bh);
trust_sb:
count = sb_count;
goto done;
Ecount:
printk("sysv_count_free_blocks: free block count was %d, "
"correcting to %d\n", sb_count, count);
if (!(sb->s_flags & MS_RDONLY)) {
*sbi->s_free_blocks = cpu_to_fs32(sbi, count);
dirty_sb(sb);
}
goto done;
}
|
