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/buffer_head.h> 13 #include <linux/module.h> 14 #include <linux/fs.h> 15 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 sector_t _efs_bmap(struct address_space *mapping, sector_t block) 21 { 22 return generic_block_bmap(mapping,block,efs_get_block); 23 } 24 static const 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 { 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; 163 164 read_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 } 170 171 static inline efs_block_t 172 efs_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 } 191 192 efs_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 } 304 305 MODULE_LICENSE("GPL"); 306