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
efs_read_folio(struct file * file,struct folio * folio)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
_efs_bmap(struct address_space * mapping,sector_t block)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
extent_copy(efs_extent * src,efs_extent * dst)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
efs_iget(struct super_block * super,unsigned long ino)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(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(-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(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_t)be16_to_cpu(efs_inode->di_uid));
104 i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
105 inode->i_size = be32_to_cpu(efs_inode->di_size);
106 inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
107 inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
108 inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 0);
109 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = 0;
110
111 /* this is the number of blocks in the file */
112 if (inode->i_size == 0) {
113 inode->i_blocks = 0;
114 } else {
115 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
116 }
117
118 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
119 if (rdev == 0xffff) {
120 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
121 if (sysv_major(rdev) > 0xfff)
122 device = 0;
123 else
124 device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
125 } else
126 device = old_decode_dev(rdev);
127
128 /* get the number of extents for this object */
129 in->numextents = be16_to_cpu(efs_inode->di_numextents);
130 in->lastextent = 0;
131
132 /* copy the extents contained within the inode to memory */
133 for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
134 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
135 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
136 pr_warn("extent %d has bad magic number in inode %lu\n",
137 i, inode->i_ino);
138 brelse(bh);
139 goto read_inode_error;
140 }
141 }
142
143 brelse(bh);
144 pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
145 inode->i_ino, in->numextents, inode->i_mode);
146 switch (inode->i_mode & S_IFMT) {
147 case S_IFDIR:
148 inode->i_op = &efs_dir_inode_operations;
149 inode->i_fop = &efs_dir_operations;
150 break;
151 case S_IFREG:
152 inode->i_fop = &generic_ro_fops;
153 inode->i_data.a_ops = &efs_aops;
154 break;
155 case S_IFLNK:
156 inode->i_op = &page_symlink_inode_operations;
157 inode_nohighmem(inode);
158 inode->i_data.a_ops = &efs_symlink_aops;
159 break;
160 case S_IFCHR:
161 case S_IFBLK:
162 case S_IFIFO:
163 init_special_inode(inode, inode->i_mode, device);
164 break;
165 default:
166 pr_warn("unsupported inode mode %o\n", inode->i_mode);
167 goto read_inode_error;
168 break;
169 }
170
171 unlock_new_inode(inode);
172 return inode;
173
174 read_inode_error:
175 pr_warn("failed to read inode %lu\n", inode->i_ino);
176 iget_failed(inode);
177 return ERR_PTR(-EIO);
178 }
179
180 static inline efs_block_t
efs_extent_check(efs_extent * ptr,efs_block_t block,struct efs_sb_info * sb)181 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
182 efs_block_t start;
183 efs_block_t length;
184 efs_block_t offset;
185
186 /*
187 * given an extent and a logical block within a file,
188 * can this block be found within this extent ?
189 */
190 start = ptr->cooked.ex_bn;
191 length = ptr->cooked.ex_length;
192 offset = ptr->cooked.ex_offset;
193
194 if ((block >= offset) && (block < offset+length)) {
195 return(sb->fs_start + start + block - offset);
196 } else {
197 return 0;
198 }
199 }
200
efs_map_block(struct inode * inode,efs_block_t block)201 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
202 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
203 struct efs_inode_info *in = INODE_INFO(inode);
204 struct buffer_head *bh = NULL;
205
206 int cur, last, first = 1;
207 int ibase, ioffset, dirext, direxts, indext, indexts;
208 efs_block_t iblock, result = 0, lastblock = 0;
209 efs_extent ext, *exts;
210
211 last = in->lastextent;
212
213 if (in->numextents <= EFS_DIRECTEXTENTS) {
214 /* first check the last extent we returned */
215 if ((result = efs_extent_check(&in->extents[last], block, sb)))
216 return result;
217
218 /* if we only have one extent then nothing can be found */
219 if (in->numextents == 1) {
220 pr_err("%s() failed to map (1 extent)\n", __func__);
221 return 0;
222 }
223
224 direxts = in->numextents;
225
226 /*
227 * check the stored extents in the inode
228 * start with next extent and check forwards
229 */
230 for(dirext = 1; dirext < direxts; dirext++) {
231 cur = (last + dirext) % in->numextents;
232 if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
233 in->lastextent = cur;
234 return result;
235 }
236 }
237
238 pr_err("%s() failed to map block %u (dir)\n", __func__, block);
239 return 0;
240 }
241
242 pr_debug("%s(): indirect search for logical block %u\n",
243 __func__, block);
244 direxts = in->extents[0].cooked.ex_offset;
245 indexts = in->numextents;
246
247 for(indext = 0; indext < indexts; indext++) {
248 cur = (last + indext) % indexts;
249
250 /*
251 * work out which direct extent contains `cur'.
252 *
253 * also compute ibase: i.e. the number of the first
254 * indirect extent contained within direct extent `cur'.
255 *
256 */
257 ibase = 0;
258 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
259 ibase += in->extents[dirext].cooked.ex_length *
260 (EFS_BLOCKSIZE / sizeof(efs_extent));
261 }
262
263 if (dirext == direxts) {
264 /* should never happen */
265 pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
266 cur, block);
267 if (bh) brelse(bh);
268 return 0;
269 }
270
271 /* work out block number and offset of this indirect extent */
272 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
273 (cur - ibase) /
274 (EFS_BLOCKSIZE / sizeof(efs_extent));
275 ioffset = (cur - ibase) %
276 (EFS_BLOCKSIZE / sizeof(efs_extent));
277
278 if (first || lastblock != iblock) {
279 if (bh) brelse(bh);
280
281 bh = sb_bread(inode->i_sb, iblock);
282 if (!bh) {
283 pr_err("%s() failed at block %d\n",
284 __func__, iblock);
285 return 0;
286 }
287 pr_debug("%s(): read indirect extent block %d\n",
288 __func__, iblock);
289 first = 0;
290 lastblock = iblock;
291 }
292
293 exts = (efs_extent *) bh->b_data;
294
295 extent_copy(&(exts[ioffset]), &ext);
296
297 if (ext.cooked.ex_magic != 0) {
298 pr_err("extent %d has bad magic number in block %d\n",
299 cur, iblock);
300 if (bh) brelse(bh);
301 return 0;
302 }
303
304 if ((result = efs_extent_check(&ext, block, sb))) {
305 if (bh) brelse(bh);
306 in->lastextent = cur;
307 return result;
308 }
309 }
310 if (bh) brelse(bh);
311 pr_err("%s() failed to map block %u (indir)\n", __func__, block);
312 return 0;
313 }
314
315 MODULE_LICENSE("GPL");
316