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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/buffer_head.h>
13#include <linux/module.h>
14#include <linux/fs.h>
15
16static int efs_readpage(struct file *file, struct page *page)
17{
18 return block_read_full_page(page,efs_get_block);
19}
20static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
21{
22 return generic_block_bmap(mapping,block,efs_get_block);
23}
24static struct address_space_operations efs_aops = {
25 .readpage = efs_readpage,
26 .sync_page = block_sync_page,
27 .bmap = _efs_bmap
28};
29
30static 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
48void efs_read_inode(struct inode *inode)
49{
50 int i, inode_index;
51 dev_t device;
52 u32 rdev;
53 struct buffer_head *bh;
54 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
55 struct efs_inode_info *in = INODE_INFO(inode);
56 efs_block_t block, offset;
57 struct efs_dinode *efs_inode;
58
59 /*
60 ** EFS layout:
61 **
62 ** | cylinder group | cylinder group | cylinder group ..etc
63 ** |inodes|data |inodes|data |inodes|data ..etc
64 **
65 ** work out the inode block index, (considering initially that the
66 ** inodes are stored as consecutive blocks). then work out the block
67 ** number of that inode given the above layout, and finally the
68 ** offset of the inode within that block.
69 */
70
71 inode_index = inode->i_ino /
72 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
73
74 block = sb->fs_start + sb->first_block +
75 (sb->group_size * (inode_index / sb->inode_blocks)) +
76 (inode_index % sb->inode_blocks);
77
78 offset = (inode->i_ino %
79 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
80 sizeof(struct efs_dinode);
81
82 bh = sb_bread(inode->i_sb, block);
83 if (!bh) {
84 printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
85 goto read_inode_error;
86 }
87
88 efs_inode = (struct efs_dinode *) (bh->b_data + offset);
89
90 inode->i_mode = be16_to_cpu(efs_inode->di_mode);
91 inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
92 inode->i_uid = (uid_t)be16_to_cpu(efs_inode->di_uid);
93 inode->i_gid = (gid_t)be16_to_cpu(efs_inode->di_gid);
94 inode->i_size = be32_to_cpu(efs_inode->di_size);
95 inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
96 inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
97 inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
98 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
99
100 /* this is the number of blocks in the file */
101 if (inode->i_size == 0) {
102 inode->i_blocks = 0;
103 } else {
104 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
105 }
106
107 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
108 if (rdev == 0xffff) {
109 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
110 if (sysv_major(rdev) > 0xfff)
111 device = 0;
112 else
113 device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
114 } else
115 device = old_decode_dev(rdev);
116
117 /* get the number of extents for this object */
118 in->numextents = be16_to_cpu(efs_inode->di_numextents);
119 in->lastextent = 0;
120
121 /* copy the extents contained within the inode to memory */
122 for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
123 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
124 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
125 printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino);
126 brelse(bh);
127 goto read_inode_error;
128 }
129 }
130
131 brelse(bh);
132
133#ifdef DEBUG
134 printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
135 inode->i_ino, in->numextents, inode->i_mode);
136#endif
137
138 switch (inode->i_mode & S_IFMT) {
139 case S_IFDIR:
140 inode->i_op = &efs_dir_inode_operations;
141 inode->i_fop = &efs_dir_operations;
142 break;
143 case S_IFREG:
144 inode->i_fop = &generic_ro_fops;
145 inode->i_data.a_ops = &efs_aops;
146 break;
147 case S_IFLNK:
148 inode->i_op = &page_symlink_inode_operations;
149 inode->i_data.a_ops = &efs_symlink_aops;
150 break;
151 case S_IFCHR:
152 case S_IFBLK:
153 case S_IFIFO:
154 init_special_inode(inode, inode->i_mode, device);
155 break;
156 default:
157 printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
158 goto read_inode_error;
159 break;
160 }
161
162 return;
163
164read_inode_error:
165 printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
166 make_bad_inode(inode);
167
168 return;
169}
170
171static inline efs_block_t
172efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
173 efs_block_t start;
174 efs_block_t length;
175 efs_block_t offset;
176
177 /*
178 * given an extent and a logical block within a file,
179 * can this block be found within this extent ?
180 */
181 start = ptr->cooked.ex_bn;
182 length = ptr->cooked.ex_length;
183 offset = ptr->cooked.ex_offset;
184
185 if ((block >= offset) && (block < offset+length)) {
186 return(sb->fs_start + start + block - offset);
187 } else {
188 return 0;
189 }
190}
191
192efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
193 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
194 struct efs_inode_info *in = INODE_INFO(inode);
195 struct buffer_head *bh = NULL;
196
197 int cur, last, first = 1;
198 int ibase, ioffset, dirext, direxts, indext, indexts;
199 efs_block_t iblock, result = 0, lastblock = 0;
200 efs_extent ext, *exts;
201
202 last = in->lastextent;
203
204 if (in->numextents <= EFS_DIRECTEXTENTS) {
205 /* first check the last extent we returned */
206 if ((result = efs_extent_check(&in->extents[last], block, sb)))
207 return result;
208
209 /* if we only have one extent then nothing can be found */
210 if (in->numextents == 1) {
211 printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n");
212 return 0;
213 }
214
215 direxts = in->numextents;
216
217 /*
218 * check the stored extents in the inode
219 * start with next extent and check forwards
220 */
221 for(dirext = 1; dirext < direxts; dirext++) {
222 cur = (last + dirext) % in->numextents;
223 if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
224 in->lastextent = cur;
225 return result;
226 }
227 }
228
229 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
230 return 0;
231 }
232
233#ifdef DEBUG
234 printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
235#endif
236 direxts = in->extents[0].cooked.ex_offset;
237 indexts = in->numextents;
238
239 for(indext = 0; indext < indexts; indext++) {
240 cur = (last + indext) % indexts;
241
242 /*
243 * work out which direct extent contains `cur'.
244 *
245 * also compute ibase: i.e. the number of the first
246 * indirect extent contained within direct extent `cur'.
247 *
248 */
249 ibase = 0;
250 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
251 ibase += in->extents[dirext].cooked.ex_length *
252 (EFS_BLOCKSIZE / sizeof(efs_extent));
253 }
254
255 if (dirext == direxts) {
256 /* should never happen */
257 printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block);
258 if (bh) brelse(bh);
259 return 0;
260 }
261
262 /* work out block number and offset of this indirect extent */
263 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
264 (cur - ibase) /
265 (EFS_BLOCKSIZE / sizeof(efs_extent));
266 ioffset = (cur - ibase) %
267 (EFS_BLOCKSIZE / sizeof(efs_extent));
268
269 if (first || lastblock != iblock) {
270 if (bh) brelse(bh);
271
272 bh = sb_bread(inode->i_sb, iblock);
273 if (!bh) {
274 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
275 return 0;
276 }
277#ifdef DEBUG
278 printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
279#endif
280 first = 0;
281 lastblock = iblock;
282 }
283
284 exts = (efs_extent *) bh->b_data;
285
286 extent_copy(&(exts[ioffset]), &ext);
287
288 if (ext.cooked.ex_magic != 0) {
289 printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
290 if (bh) brelse(bh);
291 return 0;
292 }
293
294 if ((result = efs_extent_check(&ext, block, sb))) {
295 if (bh) brelse(bh);
296 in->lastextent = cur;
297 return result;
298 }
299 }
300 if (bh) brelse(bh);
301 printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
302 return 0;
303}
304
305MODULE_LICENSE("GPL");