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
|
/*
* fs/bfs/file.c
* BFS file operations.
* Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
*
* Make the file block allocation algorithm understand the size
* of the underlying block device.
* Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
*
*/
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include "bfs.h"
#undef DEBUG
#ifdef DEBUG
#define dprintf(x...) printf(x)
#else
#define dprintf(x...)
#endif
const struct file_operations bfs_file_operations = {
.llseek = generic_file_llseek,
.read = new_sync_read,
.read_iter = generic_file_read_iter,
.write = new_sync_write,
.write_iter = generic_file_write_iter,
.mmap = generic_file_mmap,
.splice_read = generic_file_splice_read,
};
static int bfs_move_block(unsigned long from, unsigned long to,
struct super_block *sb)
{
struct buffer_head *bh, *new;
bh = sb_bread(sb, from);
if (!bh)
return -EIO;
new = sb_getblk(sb, to);
memcpy(new->b_data, bh->b_data, bh->b_size);
mark_buffer_dirty(new);
bforget(bh);
brelse(new);
return 0;
}
static int bfs_move_blocks(struct super_block *sb, unsigned long start,
unsigned long end, unsigned long where)
{
unsigned long i;
dprintf("%08lx-%08lx->%08lx\n", start, end, where);
for (i = start; i <= end; i++)
if(bfs_move_block(i, where + i, sb)) {
dprintf("failed to move block %08lx -> %08lx\n", i,
where + i);
return -EIO;
}
return 0;
}
static int bfs_get_block(struct inode *inode, sector_t block,
struct buffer_head *bh_result, int create)
{
unsigned long phys;
int err;
struct super_block *sb = inode->i_sb;
struct bfs_sb_info *info = BFS_SB(sb);
struct bfs_inode_info *bi = BFS_I(inode);
phys = bi->i_sblock + block;
if (!create) {
if (phys <= bi->i_eblock) {
dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
create, (unsigned long)block, phys);
map_bh(bh_result, sb, phys);
}
return 0;
}
/*
* If the file is not empty and the requested block is within the
* range of blocks allocated for this file, we can grant it.
*/
if (bi->i_sblock && (phys <= bi->i_eblock)) {
dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
create, (unsigned long)block, phys);
map_bh(bh_result, sb, phys);
return 0;
}
/* The file will be extended, so let's see if there is enough space. */
if (phys >= info->si_blocks)
return -ENOSPC;
/* The rest has to be protected against itself. */
mutex_lock(&info->bfs_lock);
/*
* If the last data block for this file is the last allocated
* block, we can extend the file trivially, without moving it
* anywhere.
*/
if (bi->i_eblock == info->si_lf_eblk) {
dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
create, (unsigned long)block, phys);
map_bh(bh_result, sb, phys);
info->si_freeb -= phys - bi->i_eblock;
info->si_lf_eblk = bi->i_eblock = phys;
mark_inode_dirty(inode);
err = 0;
goto out;
}
/* Ok, we have to move this entire file to the next free block. */
phys = info->si_lf_eblk + 1;
if (phys + block >= info->si_blocks) {
err = -ENOSPC;
goto out;
}
if (bi->i_sblock) {
err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
bi->i_eblock, phys);
if (err) {
dprintf("failed to move ino=%08lx -> fs corruption\n",
inode->i_ino);
goto out;
}
} else
err = 0;
dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
create, (unsigned long)block, phys);
bi->i_sblock = phys;
phys += block;
info->si_lf_eblk = bi->i_eblock = phys;
/*
* This assumes nothing can write the inode back while we are here
* and thus update inode->i_blocks! (XXX)
*/
info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
mark_inode_dirty(inode);
map_bh(bh_result, sb, phys);
out:
mutex_unlock(&info->bfs_lock);
return err;
}
static int bfs_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, bfs_get_block, wbc);
}
static int bfs_readpage(struct file *file, struct page *page)
{
return block_read_full_page(page, bfs_get_block);
}
static void bfs_write_failed(struct address_space *mapping, loff_t to)
{
struct inode *inode = mapping->host;
if (to > inode->i_size)
truncate_pagecache(inode, inode->i_size);
}
static int bfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
int ret;
ret = block_write_begin(mapping, pos, len, flags, pagep,
bfs_get_block);
if (unlikely(ret))
bfs_write_failed(mapping, pos + len);
return ret;
}
static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
{
return generic_block_bmap(mapping, block, bfs_get_block);
}
const struct address_space_operations bfs_aops = {
.readpage = bfs_readpage,
.writepage = bfs_writepage,
.write_begin = bfs_write_begin,
.write_end = generic_write_end,
.bmap = bfs_bmap,
};
const struct inode_operations bfs_file_inops;
|
