1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * inode.c |
4 | * |
5 | * Copyright (c) 1999 Al Smith |
6 | * |
7 | * Portions derived from work (c) 1995,1996 Christian Vogelgsang, |
8 | * and from work (c) 1998 Mike Shaver. |
9 | */ |
10 | |
11 | #include <linux/buffer_head.h> |
12 | #include <linux/module.h> |
13 | #include <linux/fs.h> |
14 | #include "efs.h" |
15 | #include <linux/efs_fs_sb.h> |
16 | |
17 | static int efs_read_folio(struct file *file, struct folio *folio) |
18 | { |
19 | return block_read_full_folio(folio, efs_get_block); |
20 | } |
21 | |
22 | static sector_t _efs_bmap(struct address_space *mapping, sector_t block) |
23 | { |
24 | return generic_block_bmap(mapping,block,efs_get_block); |
25 | } |
26 | |
27 | static const struct address_space_operations efs_aops = { |
28 | .read_folio = efs_read_folio, |
29 | .bmap = _efs_bmap |
30 | }; |
31 | |
32 | static inline void extent_copy(efs_extent *src, efs_extent *dst) { |
33 | /* |
34 | * this is slightly evil. it doesn't just copy |
35 | * efs_extent from src to dst, it also mangles |
36 | * the bits so that dst ends up in cpu byte-order. |
37 | */ |
38 | |
39 | dst->cooked.ex_magic = (unsigned int) src->raw[0]; |
40 | dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) | |
41 | ((unsigned int) src->raw[2] << 8) | |
42 | ((unsigned int) src->raw[3] << 0); |
43 | dst->cooked.ex_length = (unsigned int) src->raw[4]; |
44 | dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) | |
45 | ((unsigned int) src->raw[6] << 8) | |
46 | ((unsigned int) src->raw[7] << 0); |
47 | return; |
48 | } |
49 | |
50 | struct inode *efs_iget(struct super_block *super, unsigned long ino) |
51 | { |
52 | int i, inode_index; |
53 | dev_t device; |
54 | u32 rdev; |
55 | struct buffer_head *bh; |
56 | struct efs_sb_info *sb = SUPER_INFO(sb: super); |
57 | struct efs_inode_info *in; |
58 | efs_block_t block, offset; |
59 | struct efs_dinode *efs_inode; |
60 | struct inode *inode; |
61 | |
62 | inode = iget_locked(super, ino); |
63 | if (!inode) |
64 | return ERR_PTR(error: -ENOMEM); |
65 | if (!(inode->i_state & I_NEW)) |
66 | return inode; |
67 | |
68 | in = INODE_INFO(inode); |
69 | |
70 | /* |
71 | ** EFS layout: |
72 | ** |
73 | ** | cylinder group | cylinder group | cylinder group ..etc |
74 | ** |inodes|data |inodes|data |inodes|data ..etc |
75 | ** |
76 | ** work out the inode block index, (considering initially that the |
77 | ** inodes are stored as consecutive blocks). then work out the block |
78 | ** number of that inode given the above layout, and finally the |
79 | ** offset of the inode within that block. |
80 | */ |
81 | |
82 | inode_index = inode->i_ino / |
83 | (EFS_BLOCKSIZE / sizeof(struct efs_dinode)); |
84 | |
85 | block = sb->fs_start + sb->first_block + |
86 | (sb->group_size * (inode_index / sb->inode_blocks)) + |
87 | (inode_index % sb->inode_blocks); |
88 | |
89 | offset = (inode->i_ino % |
90 | (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) * |
91 | sizeof(struct efs_dinode); |
92 | |
93 | bh = sb_bread(sb: inode->i_sb, block); |
94 | if (!bh) { |
95 | pr_warn("%s() failed at block %d\n" , __func__, block); |
96 | goto read_inode_error; |
97 | } |
98 | |
99 | efs_inode = (struct efs_dinode *) (bh->b_data + offset); |
100 | |
101 | inode->i_mode = be16_to_cpu(efs_inode->di_mode); |
102 | set_nlink(inode, be16_to_cpu(efs_inode->di_nlink)); |
103 | i_uid_write(inode, uid: (uid_t)be16_to_cpu(efs_inode->di_uid)); |
104 | i_gid_write(inode, gid: (gid_t)be16_to_cpu(efs_inode->di_gid)); |
105 | inode->i_size = be32_to_cpu(efs_inode->di_size); |
106 | inode_set_atime(inode, be32_to_cpu(efs_inode->di_atime), nsec: 0); |
107 | inode_set_mtime(inode, be32_to_cpu(efs_inode->di_mtime), nsec: 0); |
108 | inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), nsec: 0); |
109 | |
110 | /* this is the number of blocks in the file */ |
111 | if (inode->i_size == 0) { |
112 | inode->i_blocks = 0; |
113 | } else { |
114 | inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1; |
115 | } |
116 | |
117 | rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev); |
118 | if (rdev == 0xffff) { |
119 | rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev); |
120 | if (sysv_major(dev: rdev) > 0xfff) |
121 | device = 0; |
122 | else |
123 | device = MKDEV(sysv_major(rdev), sysv_minor(rdev)); |
124 | } else |
125 | device = old_decode_dev(val: rdev); |
126 | |
127 | /* get the number of extents for this object */ |
128 | in->numextents = be16_to_cpu(efs_inode->di_numextents); |
129 | in->lastextent = 0; |
130 | |
131 | /* copy the extents contained within the inode to memory */ |
132 | for(i = 0; i < EFS_DIRECTEXTENTS; i++) { |
133 | extent_copy(src: &(efs_inode->di_u.di_extents[i]), dst: &(in->extents[i])); |
134 | if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) { |
135 | pr_warn("extent %d has bad magic number in inode %lu\n" , |
136 | i, inode->i_ino); |
137 | brelse(bh); |
138 | goto read_inode_error; |
139 | } |
140 | } |
141 | |
142 | brelse(bh); |
143 | pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n" , |
144 | inode->i_ino, in->numextents, inode->i_mode); |
145 | switch (inode->i_mode & S_IFMT) { |
146 | case S_IFDIR: |
147 | inode->i_op = &efs_dir_inode_operations; |
148 | inode->i_fop = &efs_dir_operations; |
149 | break; |
150 | case S_IFREG: |
151 | inode->i_fop = &generic_ro_fops; |
152 | inode->i_data.a_ops = &efs_aops; |
153 | break; |
154 | case S_IFLNK: |
155 | inode->i_op = &page_symlink_inode_operations; |
156 | inode_nohighmem(inode); |
157 | inode->i_data.a_ops = &efs_symlink_aops; |
158 | break; |
159 | case S_IFCHR: |
160 | case S_IFBLK: |
161 | case S_IFIFO: |
162 | init_special_inode(inode, inode->i_mode, device); |
163 | break; |
164 | default: |
165 | pr_warn("unsupported inode mode %o\n" , inode->i_mode); |
166 | goto read_inode_error; |
167 | break; |
168 | } |
169 | |
170 | unlock_new_inode(inode); |
171 | return inode; |
172 | |
173 | read_inode_error: |
174 | pr_warn("failed to read inode %lu\n" , inode->i_ino); |
175 | iget_failed(inode); |
176 | return ERR_PTR(error: -EIO); |
177 | } |
178 | |
179 | static inline efs_block_t |
180 | efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) { |
181 | efs_block_t start; |
182 | efs_block_t length; |
183 | efs_block_t offset; |
184 | |
185 | /* |
186 | * given an extent and a logical block within a file, |
187 | * can this block be found within this extent ? |
188 | */ |
189 | start = ptr->cooked.ex_bn; |
190 | length = ptr->cooked.ex_length; |
191 | offset = ptr->cooked.ex_offset; |
192 | |
193 | if ((block >= offset) && (block < offset+length)) { |
194 | return(sb->fs_start + start + block - offset); |
195 | } else { |
196 | return 0; |
197 | } |
198 | } |
199 | |
200 | efs_block_t efs_map_block(struct inode *inode, efs_block_t block) { |
201 | struct efs_sb_info *sb = SUPER_INFO(sb: inode->i_sb); |
202 | struct efs_inode_info *in = INODE_INFO(inode); |
203 | struct buffer_head *bh = NULL; |
204 | |
205 | int cur, last, first = 1; |
206 | int ibase, ioffset, dirext, direxts, indext, indexts; |
207 | efs_block_t iblock, result = 0, lastblock = 0; |
208 | efs_extent ext, *exts; |
209 | |
210 | last = in->lastextent; |
211 | |
212 | if (in->numextents <= EFS_DIRECTEXTENTS) { |
213 | /* first check the last extent we returned */ |
214 | if ((result = efs_extent_check(ptr: &in->extents[last], block, sb))) |
215 | return result; |
216 | |
217 | /* if we only have one extent then nothing can be found */ |
218 | if (in->numextents == 1) { |
219 | pr_err("%s() failed to map (1 extent)\n" , __func__); |
220 | return 0; |
221 | } |
222 | |
223 | direxts = in->numextents; |
224 | |
225 | /* |
226 | * check the stored extents in the inode |
227 | * start with next extent and check forwards |
228 | */ |
229 | for(dirext = 1; dirext < direxts; dirext++) { |
230 | cur = (last + dirext) % in->numextents; |
231 | if ((result = efs_extent_check(ptr: &in->extents[cur], block, sb))) { |
232 | in->lastextent = cur; |
233 | return result; |
234 | } |
235 | } |
236 | |
237 | pr_err("%s() failed to map block %u (dir)\n" , __func__, block); |
238 | return 0; |
239 | } |
240 | |
241 | pr_debug("%s(): indirect search for logical block %u\n" , |
242 | __func__, block); |
243 | direxts = in->extents[0].cooked.ex_offset; |
244 | indexts = in->numextents; |
245 | |
246 | for(indext = 0; indext < indexts; indext++) { |
247 | cur = (last + indext) % indexts; |
248 | |
249 | /* |
250 | * work out which direct extent contains `cur'. |
251 | * |
252 | * also compute ibase: i.e. the number of the first |
253 | * indirect extent contained within direct extent `cur'. |
254 | * |
255 | */ |
256 | ibase = 0; |
257 | for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { |
258 | ibase += in->extents[dirext].cooked.ex_length * |
259 | (EFS_BLOCKSIZE / sizeof(efs_extent)); |
260 | } |
261 | |
262 | if (dirext == direxts) { |
263 | /* should never happen */ |
264 | pr_err("couldn't find direct extent for indirect extent %d (block %u)\n" , |
265 | cur, block); |
266 | if (bh) brelse(bh); |
267 | return 0; |
268 | } |
269 | |
270 | /* work out block number and offset of this indirect extent */ |
271 | iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn + |
272 | (cur - ibase) / |
273 | (EFS_BLOCKSIZE / sizeof(efs_extent)); |
274 | ioffset = (cur - ibase) % |
275 | (EFS_BLOCKSIZE / sizeof(efs_extent)); |
276 | |
277 | if (first || lastblock != iblock) { |
278 | if (bh) brelse(bh); |
279 | |
280 | bh = sb_bread(sb: inode->i_sb, block: iblock); |
281 | if (!bh) { |
282 | pr_err("%s() failed at block %d\n" , |
283 | __func__, iblock); |
284 | return 0; |
285 | } |
286 | pr_debug("%s(): read indirect extent block %d\n" , |
287 | __func__, iblock); |
288 | first = 0; |
289 | lastblock = iblock; |
290 | } |
291 | |
292 | exts = (efs_extent *) bh->b_data; |
293 | |
294 | extent_copy(src: &(exts[ioffset]), dst: &ext); |
295 | |
296 | if (ext.cooked.ex_magic != 0) { |
297 | pr_err("extent %d has bad magic number in block %d\n" , |
298 | cur, iblock); |
299 | if (bh) brelse(bh); |
300 | return 0; |
301 | } |
302 | |
303 | if ((result = efs_extent_check(ptr: &ext, block, sb))) { |
304 | if (bh) brelse(bh); |
305 | in->lastextent = cur; |
306 | return result; |
307 | } |
308 | } |
309 | if (bh) brelse(bh); |
310 | pr_err("%s() failed to map block %u (indir)\n" , __func__, block); |
311 | return 0; |
312 | } |
313 | |
314 | MODULE_LICENSE("GPL" ); |
315 | |