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(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_set_atime(inode, be32_to_cpu(efs_inode->di_atime), 0);
107 inode_set_mtime(inode, be32_to_cpu(efs_inode->di_mtime), 0);
108 inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 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(rdev) > 0xfff)
121 device = 0;
122 else
123 device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
124 } else
125 device = old_decode_dev(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(&(efs_inode->di_u.di_extents[i]), &(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(-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(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(&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(&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(inode->i_sb, 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(&(exts[ioffset]), &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(&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_DESCRIPTION("Extent File System (efs)");
315 MODULE_LICENSE("GPL");
316
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