1 /*
2 * inode.c
3 *
4 * Copyright (c) 1999 Al Smith
5 *
6 * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
7 * and from work (c) 1998 Mike Shaver.
8 */
9
10 #include <linux/efs_fs.h>
11 #include <linux/efs_fs_sb.h>
12 #include <linux/module.h>
13
14
15 extern int efs_get_block(struct inode *, long, struct buffer_head *, int);
16 static int efs_readpage(struct file *file, struct page *page)
17 {
18 return block_read_full_page(page,efs_get_block);
19 }
20 static int _efs_bmap(struct address_space *mapping, long block)
21 {
22 return generic_block_bmap(mapping,block,efs_get_block);
23 }
24 struct address_space_operations efs_aops = {
25 readpage: efs_readpage,
26 sync_page: block_sync_page,
27 bmap: _efs_bmap
28 };
29
30 static inline void extent_copy(efs_extent *src, efs_extent *dst) {
31 /*
32 * this is slightly evil. it doesn't just copy
33 * efs_extent from src to dst, it also mangles
34 * the bits so that dst ends up in cpu byte-order.
35 */
36
37 dst->cooked.ex_magic = (unsigned int) src->raw[0];
38 dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) |
39 ((unsigned int) src->raw[2] << 8) |
40 ((unsigned int) src->raw[3] << 0);
41 dst->cooked.ex_length = (unsigned int) src->raw[4];
42 dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
43 ((unsigned int) src->raw[6] << 8) |
44 ((unsigned int) src->raw[7] << 0);
45 return;
46 }
47
48 void efs_read_inode(struct inode *inode) {
49 int i, inode_index;
50 dev_t device;
51 struct buffer_head *bh;
52 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
53 struct efs_inode_info *in = INODE_INFO(inode);
54 efs_block_t block, offset;
55 struct efs_dinode *efs_inode;
56
57 /*
58 ** EFS layout:
59 **
60 ** | cylinder group | cylinder group | cylinder group ..etc
61 ** |inodes|data |inodes|data |inodes|data ..etc
62 **
63 ** work out the inode block index, (considering initially that the
64 ** inodes are stored as consecutive blocks). then work out the block
65 ** number of that inode given the above layout, and finally the
66 ** offset of the inode within that block.
67 */
68
69 inode_index = inode->i_ino /
70 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
71
72 block = sb->fs_start + sb->first_block +
73 (sb->group_size * (inode_index / sb->inode_blocks)) +
74 (inode_index % sb->inode_blocks);
75
76 offset = (inode->i_ino %
77 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
78 sizeof(struct efs_dinode);
79
80 bh = sb_bread(inode->i_sb, block);
81 if (!bh) {
82 printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
83 goto read_inode_error;
84 }
85
86 efs_inode = (struct efs_dinode *) (bh->b_data + offset);
87
88 inode->i_mode = be16_to_cpu(efs_inode->di_mode);
89 inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
90 inode->i_uid = (uid_t)be16_to_cpu(efs_inode->di_uid);
91 inode->i_gid = (gid_t)be16_to_cpu(efs_inode->di_gid);
92 inode->i_size = be32_to_cpu(efs_inode->di_size);
93 inode->i_atime = be32_to_cpu(efs_inode->di_atime);
94 inode->i_mtime = be32_to_cpu(efs_inode->di_mtime);
95 inode->i_ctime = be32_to_cpu(efs_inode->di_ctime);
96
97 /* this is the number of blocks in the file */
98 if (inode->i_size == 0) {
99 inode->i_blocks = 0;
100 } else {
101 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
102 }
103
104 /*
105 * BUG: irix dev_t is 32-bits. linux dev_t is only 16-bits.
106 *
107 * apparently linux will change to 32-bit dev_t sometime during
108 * linux 2.3.
109 *
110 * as is, this code maps devices that can't be represented in
111 * 16-bits (ie major > 255 or minor > 255) to major = minor = 255.
112 *
113 * during 2.3 when 32-bit dev_t become available, we should test
114 * to see whether odev contains 65535. if this is the case then we
115 * should then do device = be32_to_cpu(efs_inode->di_u.di_dev.ndev).
116 */
117 device = be16_to_cpu(efs_inode->di_u.di_dev.odev);
118
119 /* get the number of extents for this object */
120 in->numextents = be16_to_cpu(efs_inode->di_numextents);
121 in->lastextent = 0;
122
123 /* copy the extents contained within the inode to memory */
124 for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
125 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
126 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
127 printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino);
128 brelse(bh);
129 goto read_inode_error;
130 }
131 }
132
133 brelse(bh);
134
135 #ifdef DEBUG
136 printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
137 inode->i_ino, in->numextents, inode->i_mode);
138 #endif
139
140 switch (inode->i_mode & S_IFMT) {
141 case S_IFDIR:
142 inode->i_op = &efs_dir_inode_operations;
143 inode->i_fop = &efs_dir_operations;
144 break;
145 case S_IFREG:
146 inode->i_fop = &generic_ro_fops;
147 inode->i_data.a_ops = &efs_aops;
148 break;
149 case S_IFLNK:
150 inode->i_op = &page_symlink_inode_operations;
151 inode->i_data.a_ops = &efs_symlink_aops;
152 break;
153 case S_IFCHR:
154 case S_IFBLK:
155 case S_IFIFO:
156 init_special_inode(inode, inode->i_mode, device);
157 break;
158 default:
159 printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
160 goto read_inode_error;
161 break;
162 }
163
164 return;
165
166 read_inode_error:
167 printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
168 make_bad_inode(inode);
169
170 return;
171 }
172
173 static inline efs_block_t
174 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
175 efs_block_t start;
176 efs_block_t length;
177 efs_block_t offset;
178
179 /*
180 * given an extent and a logical block within a file,
181 * can this block be found within this extent ?
182 */
183 start = ptr->cooked.ex_bn;
184 length = ptr->cooked.ex_length;
185 offset = ptr->cooked.ex_offset;
186
187 if ((block >= offset) && (block < offset+length)) {
188 return(sb->fs_start + start + block - offset);
189 } else {
190 return 0;
191 }
192 }
193
194 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
195 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
196 struct efs_inode_info *in = INODE_INFO(inode);
197 struct buffer_head *bh = NULL;
198
199 int cur, last, first = 1;
200 int ibase, ioffset, dirext, direxts, indext, indexts;
201 efs_block_t iblock, result = 0, lastblock = 0;
202 efs_extent ext, *exts;
203
204 last = in->lastextent;
205
206 if (in->numextents <= EFS_DIRECTEXTENTS) {
207 /* first check the last extent we returned */
208 if ((result = efs_extent_check(&in->extents[last], block, sb)))
209 return result;
210
211 /* if we only have one extent then nothing can be found */
212 if (in->numextents == 1) {
213 printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n");
214 return 0;
215 }
216
217 direxts = in->numextents;
218
219 /*
220 * check the stored extents in the inode
221 * start with next extent and check forwards
222 */
223 for(dirext = 1; dirext < direxts; dirext++) {
224 cur = (last + dirext) % in->numextents;
225 if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
226 in->lastextent = cur;
227 return result;
228 }
229 }
230
231 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
232 return 0;
233 }
234
235 #ifdef DEBUG
236 printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
237 #endif
238 direxts = in->extents[0].cooked.ex_offset;
239 indexts = in->numextents;
240
241 for(indext = 0; indext < indexts; indext++) {
242 cur = (last + indext) % indexts;
243
244 /*
245 * work out which direct extent contains `cur'.
246 *
247 * also compute ibase: i.e. the number of the first
248 * indirect extent contained within direct extent `cur'.
249 *
250 */
251 ibase = 0;
252 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
253 ibase += in->extents[dirext].cooked.ex_length *
254 (EFS_BLOCKSIZE / sizeof(efs_extent));
255 }
256
257 if (dirext == direxts) {
258 /* should never happen */
259 printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block);
260 if (bh) brelse(bh);
261 return 0;
262 }
263
264 /* work out block number and offset of this indirect extent */
265 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
266 (cur - ibase) /
267 (EFS_BLOCKSIZE / sizeof(efs_extent));
268 ioffset = (cur - ibase) %
269 (EFS_BLOCKSIZE / sizeof(efs_extent));
270
271 if (first || lastblock != iblock) {
272 if (bh) brelse(bh);
273
274 bh = sb_bread(inode->i_sb, iblock);
275 if (!bh) {
276 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
277 return 0;
278 }
279 #ifdef DEBUG
280 printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
281 #endif
282 first = 0;
283 lastblock = iblock;
284 }
285
286 exts = (efs_extent *) bh->b_data;
287
288 extent_copy(&(exts[ioffset]), &ext);
289
290 if (ext.cooked.ex_magic != 0) {
291 printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
292 if (bh) brelse(bh);
293 return 0;
294 }
295
296 if ((result = efs_extent_check(&ext, block, sb))) {
297 if (bh) brelse(bh);
298 in->lastextent = cur;
299 return result;
300 }
301 }
302 if (bh) brelse(bh);
303 printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
304 return 0;
305 }
306
307 MODULE_LICENSE("GPL");
308
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