4 * Copyright (c) 1999 Al Smith
6 * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
7 * and from work (c) 1998 Mike Shaver.
10 #include <linux/efs_fs.h>
11 #include <linux/efs_fs_sb.h>
12 #include <linux/buffer_head.h>
13 #include <linux/module.h>
17 extern int efs_get_block(struct inode *, sector_t, struct buffer_head *, int);
18 static int efs_readpage(struct file *file, struct page *page)
20 return block_read_full_page(page,efs_get_block);
22 static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
24 return generic_block_bmap(mapping,block,efs_get_block);
26 struct address_space_operations efs_aops = {
27 .readpage = efs_readpage,
28 .sync_page = block_sync_page,
32 static inline void extent_copy(efs_extent *src, efs_extent *dst) {
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.
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);
50 void efs_read_inode(struct inode *inode)
55 struct buffer_head *bh;
56 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
57 struct efs_inode_info *in = INODE_INFO(inode);
58 efs_block_t block, offset;
59 struct efs_dinode *efs_inode;
64 ** | cylinder group | cylinder group | cylinder group ..etc
65 ** |inodes|data |inodes|data |inodes|data ..etc
67 ** work out the inode block index, (considering initially that the
68 ** inodes are stored as consecutive blocks). then work out the block
69 ** number of that inode given the above layout, and finally the
70 ** offset of the inode within that block.
73 inode_index = inode->i_ino /
74 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
76 block = sb->fs_start + sb->first_block +
77 (sb->group_size * (inode_index / sb->inode_blocks)) +
78 (inode_index % sb->inode_blocks);
80 offset = (inode->i_ino %
81 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
82 sizeof(struct efs_dinode);
84 bh = sb_bread(inode->i_sb, block);
86 printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
87 goto read_inode_error;
90 efs_inode = (struct efs_dinode *) (bh->b_data + offset);
92 inode->i_mode = be16_to_cpu(efs_inode->di_mode);
93 inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
94 inode->i_uid = (uid_t)be16_to_cpu(efs_inode->di_uid);
95 inode->i_gid = (gid_t)be16_to_cpu(efs_inode->di_gid);
96 inode->i_size = be32_to_cpu(efs_inode->di_size);
97 inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
98 inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
99 inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
100 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
102 /* this is the number of blocks in the file */
103 if (inode->i_size == 0) {
106 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
109 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
110 if (rdev == 0xffff) {
111 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
112 if (sysv_major(rdev) > 0xfff)
115 device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
117 device = old_decode_dev(rdev);
119 /* get the number of extents for this object */
120 in->numextents = be16_to_cpu(efs_inode->di_numextents);
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);
129 goto read_inode_error;
136 printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
137 inode->i_ino, in->numextents, inode->i_mode);
140 switch (inode->i_mode & S_IFMT) {
142 inode->i_op = &efs_dir_inode_operations;
143 inode->i_fop = &efs_dir_operations;
146 inode->i_fop = &generic_ro_fops;
147 inode->i_data.a_ops = &efs_aops;
150 inode->i_op = &page_symlink_inode_operations;
151 inode->i_data.a_ops = &efs_symlink_aops;
156 init_special_inode(inode, inode->i_mode, device);
159 printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
160 goto read_inode_error;
167 printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
168 make_bad_inode(inode);
173 static inline efs_block_t
174 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
180 * given an extent and a logical block within a file,
181 * can this block be found within this extent ?
183 start = ptr->cooked.ex_bn;
184 length = ptr->cooked.ex_length;
185 offset = ptr->cooked.ex_offset;
187 if ((block >= offset) && (block < offset+length)) {
188 return(sb->fs_start + start + block - offset);
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;
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;
204 last = in->lastextent;
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)))
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");
217 direxts = in->numextents;
220 * check the stored extents in the inode
221 * start with next extent and check forwards
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;
231 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
236 printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
238 direxts = in->extents[0].cooked.ex_offset;
239 indexts = in->numextents;
241 for(indext = 0; indext < indexts; indext++) {
242 cur = (last + indext) % indexts;
245 * work out which direct extent contains `cur'.
247 * also compute ibase: i.e. the number of the first
248 * indirect extent contained within direct extent `cur'.
252 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
253 ibase += in->extents[dirext].cooked.ex_length *
254 (EFS_BLOCKSIZE / sizeof(efs_extent));
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);
264 /* work out block number and offset of this indirect extent */
265 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
267 (EFS_BLOCKSIZE / sizeof(efs_extent));
268 ioffset = (cur - ibase) %
269 (EFS_BLOCKSIZE / sizeof(efs_extent));
271 if (first || lastblock != iblock) {
274 bh = sb_bread(inode->i_sb, iblock);
276 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
280 printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
286 exts = (efs_extent *) bh->b_data;
288 extent_copy(&(exts[ioffset]), &ext);
290 if (ext.cooked.ex_magic != 0) {
291 printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
296 if ((result = efs_extent_check(&ext, block, sb))) {
298 in->lastextent = cur;
303 printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
307 MODULE_LICENSE("GPL");