1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * fs/bfs/file.c |
4 | * BFS file operations. |
5 | * Copyright (C) 1999-2018 Tigran Aivazian <aivazian.tigran@gmail.com> |
6 | * |
7 | * Make the file block allocation algorithm understand the size |
8 | * of the underlying block device. |
9 | * Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com> |
10 | * |
11 | */ |
12 | |
13 | #include <linux/fs.h> |
14 | #include <linux/mpage.h> |
15 | #include <linux/buffer_head.h> |
16 | #include "bfs.h" |
17 | |
18 | #undef DEBUG |
19 | |
20 | #ifdef DEBUG |
21 | #define dprintf(x...) printf(x) |
22 | #else |
23 | #define dprintf(x...) |
24 | #endif |
25 | |
26 | const struct file_operations bfs_file_operations = { |
27 | .llseek = generic_file_llseek, |
28 | .read_iter = generic_file_read_iter, |
29 | .write_iter = generic_file_write_iter, |
30 | .mmap = generic_file_mmap, |
31 | .splice_read = filemap_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, block: from); |
40 | if (!bh) |
41 | return -EIO; |
42 | new = sb_getblk(sb, block: to); |
43 | memcpy(new->b_data, bh->b_data, bh->b_size); |
44 | mark_buffer_dirty(bh: new); |
45 | bforget(bh); |
46 | brelse(bh: 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(from: i, to: 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 | |
74 | phys = bi->i_sblock + block; |
75 | if (!create) { |
76 | if (phys <= bi->i_eblock) { |
77 | dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n" , |
78 | create, (unsigned long)block, phys); |
79 | map_bh(bh: bh_result, sb, block: phys); |
80 | } |
81 | return 0; |
82 | } |
83 | |
84 | /* |
85 | * If the file is not empty and the requested block is within the |
86 | * range of blocks allocated for this file, we can grant it. |
87 | */ |
88 | if (bi->i_sblock && (phys <= bi->i_eblock)) { |
89 | dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n" , |
90 | create, (unsigned long)block, phys); |
91 | map_bh(bh: bh_result, sb, block: phys); |
92 | return 0; |
93 | } |
94 | |
95 | /* The file will be extended, so let's see if there is enough space. */ |
96 | if (phys >= info->si_blocks) |
97 | return -ENOSPC; |
98 | |
99 | /* The rest has to be protected against itself. */ |
100 | mutex_lock(&info->bfs_lock); |
101 | |
102 | /* |
103 | * If the last data block for this file is the last allocated |
104 | * block, we can extend the file trivially, without moving it |
105 | * anywhere. |
106 | */ |
107 | if (bi->i_eblock == info->si_lf_eblk) { |
108 | dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n" , |
109 | create, (unsigned long)block, phys); |
110 | map_bh(bh: bh_result, sb, block: phys); |
111 | info->si_freeb -= phys - bi->i_eblock; |
112 | info->si_lf_eblk = bi->i_eblock = phys; |
113 | mark_inode_dirty(inode); |
114 | err = 0; |
115 | goto out; |
116 | } |
117 | |
118 | /* Ok, we have to move this entire file to the next free block. */ |
119 | phys = info->si_lf_eblk + 1; |
120 | if (phys + block >= info->si_blocks) { |
121 | err = -ENOSPC; |
122 | goto out; |
123 | } |
124 | |
125 | if (bi->i_sblock) { |
126 | err = bfs_move_blocks(sb: inode->i_sb, start: bi->i_sblock, |
127 | end: bi->i_eblock, where: phys); |
128 | if (err) { |
129 | dprintf("failed to move ino=%08lx -> fs corruption\n" , |
130 | inode->i_ino); |
131 | goto out; |
132 | } |
133 | } else |
134 | err = 0; |
135 | |
136 | dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n" , |
137 | create, (unsigned long)block, phys); |
138 | bi->i_sblock = phys; |
139 | phys += block; |
140 | info->si_lf_eblk = bi->i_eblock = phys; |
141 | |
142 | /* |
143 | * This assumes nothing can write the inode back while we are here |
144 | * and thus update inode->i_blocks! (XXX) |
145 | */ |
146 | info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; |
147 | mark_inode_dirty(inode); |
148 | map_bh(bh: bh_result, sb, block: phys); |
149 | out: |
150 | mutex_unlock(lock: &info->bfs_lock); |
151 | return err; |
152 | } |
153 | |
154 | static int bfs_writepages(struct address_space *mapping, |
155 | struct writeback_control *wbc) |
156 | { |
157 | return mpage_writepages(mapping, wbc, get_block: bfs_get_block); |
158 | } |
159 | |
160 | static int bfs_read_folio(struct file *file, struct folio *folio) |
161 | { |
162 | return block_read_full_folio(folio, bfs_get_block); |
163 | } |
164 | |
165 | static void bfs_write_failed(struct address_space *mapping, loff_t to) |
166 | { |
167 | struct inode *inode = mapping->host; |
168 | |
169 | if (to > inode->i_size) |
170 | truncate_pagecache(inode, new: inode->i_size); |
171 | } |
172 | |
173 | static int bfs_write_begin(struct file *file, struct address_space *mapping, |
174 | loff_t pos, unsigned len, |
175 | struct page **pagep, void **fsdata) |
176 | { |
177 | int ret; |
178 | |
179 | ret = block_write_begin(mapping, pos, len, pagep, get_block: bfs_get_block); |
180 | if (unlikely(ret)) |
181 | bfs_write_failed(mapping, to: pos + len); |
182 | |
183 | return ret; |
184 | } |
185 | |
186 | static sector_t bfs_bmap(struct address_space *mapping, sector_t block) |
187 | { |
188 | return generic_block_bmap(mapping, block, bfs_get_block); |
189 | } |
190 | |
191 | const struct address_space_operations bfs_aops = { |
192 | .dirty_folio = block_dirty_folio, |
193 | .invalidate_folio = block_invalidate_folio, |
194 | .read_folio = bfs_read_folio, |
195 | .writepages = bfs_writepages, |
196 | .write_begin = bfs_write_begin, |
197 | .write_end = generic_write_end, |
198 | .migrate_folio = buffer_migrate_folio, |
199 | .bmap = bfs_bmap, |
200 | }; |
201 | |
202 | const struct inode_operations bfs_file_inops; |
203 | |