1 /*
2 * fs/bfs/file.c
3 * BFS file operations.
4 * Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
5 *
6 * Make the file block allocation algorithm understand the size
7 * of the underlying block device.
8 * Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
9 *
10 */
11
12 #include <linux/fs.h>
13 #include <linux/buffer_head.h>
14 #include "bfs.h"
15
16 #undef DEBUG
17
18 #ifdef DEBUG
19 #define dprintf(x...) printf(x)
20 #else
21 #define dprintf(x...)
22 #endif
23
24 const struct file_operations bfs_file_operations = {
25 .llseek = generic_file_llseek,
26 .read = do_sync_read,
27 .aio_read = generic_file_aio_read,
28 .write = do_sync_write,
29 .aio_write = generic_file_aio_write,
30 .mmap = generic_file_mmap,
31 .splice_read = generic_file_splice_read,
32 };
33
34 static int bfs_move_block(unsigned long from, unsigned long to,
35 struct super_block *sb)
36 {
37 struct buffer_head *bh, *new;
38
39 bh = sb_bread(sb, from);
40 if (!bh)
41 return -EIO;
42 new = sb_getblk(sb, to);
43 memcpy(new->b_data, bh->b_data, bh->b_size);
44 mark_buffer_dirty(new);
45 bforget(bh);
46 brelse(new);
47 return 0;
48 }
49
50 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
51 unsigned long end, unsigned long where)
52 {
53 unsigned long i;
54
55 dprintf("%08lx-%08lx->%08lx\n", start, end, where);
56 for (i = start; i <= end; i++)
57 if(bfs_move_block(i, where + i, sb)) {
58 dprintf("failed to move block %08lx -> %08lx\n", i,
59 where + i);
60 return -EIO;
61 }
62 return 0;
63 }
64
65 static int bfs_get_block(struct inode *inode, sector_t block,
66 struct buffer_head *bh_result, int create)
67 {
68 unsigned long phys;
69 int err;
70 struct super_block *sb = inode->i_sb;
71 struct bfs_sb_info *info = BFS_SB(sb);
72 struct bfs_inode_info *bi = BFS_I(inode);
73 struct buffer_head *sbh = info->si_sbh;
74
75 phys = bi->i_sblock + block;
76 if (!create) {
77 if (phys <= bi->i_eblock) {
78 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
79 create, (unsigned long)block, phys);
80 map_bh(bh_result, sb, phys);
81 }
82 return 0;
83 }
84
85 /*
86 * If the file is not empty and the requested block is within the
87 * range of blocks allocated for this file, we can grant it.
88 */
89 if (bi->i_sblock && (phys <= bi->i_eblock)) {
90 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
91 create, (unsigned long)block, phys);
92 map_bh(bh_result, sb, phys);
93 return 0;
94 }
95
96 /* The file will be extended, so let's see if there is enough space. */
97 if (phys >= info->si_blocks)
98 return -ENOSPC;
99
100 /* The rest has to be protected against itself. */
101 mutex_lock(&info->bfs_lock);
102
103 /*
104 * If the last data block for this file is the last allocated
105 * block, we can extend the file trivially, without moving it
106 * anywhere.
107 */
108 if (bi->i_eblock == info->si_lf_eblk) {
109 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
110 create, (unsigned long)block, phys);
111 map_bh(bh_result, sb, phys);
112 info->si_freeb -= phys - bi->i_eblock;
113 info->si_lf_eblk = bi->i_eblock = phys;
114 mark_inode_dirty(inode);
115 mark_buffer_dirty(sbh);
116 err = 0;
117 goto out;
118 }
119
120 /* Ok, we have to move this entire file to the next free block. */
121 phys = info->si_lf_eblk + 1;
122 if (phys + block >= info->si_blocks) {
123 err = -ENOSPC;
124 goto out;
125 }
126
127 if (bi->i_sblock) {
128 err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
129 bi->i_eblock, phys);
130 if (err) {
131 dprintf("failed to move ino=%08lx -> fs corruption\n",
132 inode->i_ino);
133 goto out;
134 }
135 } else
136 err = 0;
137
138 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
139 create, (unsigned long)block, phys);
140 bi->i_sblock = phys;
141 phys += block;
142 info->si_lf_eblk = bi->i_eblock = phys;
143
144 /*
145 * This assumes nothing can write the inode back while we are here
146 * and thus update inode->i_blocks! (XXX)
147 */
148 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
149 mark_inode_dirty(inode);
150 mark_buffer_dirty(sbh);
151 map_bh(bh_result, sb, phys);
152 out:
153 mutex_unlock(&info->bfs_lock);
154 return err;
155 }
156
157 static int bfs_writepage(struct page *page, struct writeback_control *wbc)
158 {
159 return block_write_full_page(page, bfs_get_block, wbc);
160 }
161
162 static int bfs_readpage(struct file *file, struct page *page)
163 {
164 return block_read_full_page(page, bfs_get_block);
165 }
166
167 static int bfs_write_begin(struct file *file, struct address_space *mapping,
168 loff_t pos, unsigned len, unsigned flags,
169 struct page **pagep, void **fsdata)
170 {
171 *pagep = NULL;
172 return block_write_begin(file, mapping, pos, len, flags,
173 pagep, fsdata, bfs_get_block);
174 }
175
176 static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
177 {
178 return generic_block_bmap(mapping, block, bfs_get_block);
179 }
180
181 const struct address_space_operations bfs_aops = {
182 .readpage = bfs_readpage,
183 .writepage = bfs_writepage,
184 .sync_page = block_sync_page,
185 .write_begin = bfs_write_begin,
186 .write_end = generic_write_end,
187 .bmap = bfs_bmap,
188 };
189
190 const struct inode_operations bfs_file_inops;
191
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