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/buffer_head.h> 11 #include <linux/module.h> 12 #include <linux/fs.h> 13 #include "efs.h" 14 #include <linux/efs_fs_sb.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 .bmap = _efs_bmap 27 }; 28 29 static inline void extent_copy(efs_extent *src, efs_extent *dst) { 30 /* 31 * this is slightly evil. it doesn't just copy 32 * efs_extent from src to dst, it also mangles 33 * the bits so that dst ends up in cpu byte-order. 34 */ 35 36 dst->cooked.ex_magic = (unsigned int) src->raw[0]; 37 dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) | 38 ((unsigned int) src->raw[2] << 8) | 39 ((unsigned int) src->raw[3] << 0); 40 dst->cooked.ex_length = (unsigned int) src->raw[4]; 41 dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) | 42 ((unsigned int) src->raw[6] << 8) | 43 ((unsigned int) src->raw[7] << 0); 44 return; 45 } 46 47 struct inode *efs_iget(struct super_block *super, unsigned long ino) 48 { 49 int i, inode_index; 50 dev_t device; 51 u32 rdev; 52 struct buffer_head *bh; 53 struct efs_sb_info *sb = SUPER_INFO(super); 54 struct efs_inode_info *in; 55 efs_block_t block, offset; 56 struct efs_dinode *efs_inode; 57 struct inode *inode; 58 59 inode = iget_locked(super, ino); 60 if (!inode) 61 return ERR_PTR(-ENOMEM); 62 if (!(inode->i_state & I_NEW)) 63 return inode; 64 65 in = INODE_INFO(inode); 66 67 /* 68 ** EFS layout: 69 ** 70 ** | cylinder group | cylinder group | cylinder group ..etc 71 ** |inodes|data |inodes|data |inodes|data ..etc 72 ** 73 ** work out the inode block index, (considering initially that the 74 ** inodes are stored as consecutive blocks). then work out the block 75 ** number of that inode given the above layout, and finally the 76 ** offset of the inode within that block. 77 */ 78 79 inode_index = inode->i_ino / 80 (EFS_BLOCKSIZE / sizeof(struct efs_dinode)); 81 82 block = sb->fs_start + sb->first_block + 83 (sb->group_size * (inode_index / sb->inode_blocks)) + 84 (inode_index % sb->inode_blocks); 85 86 offset = (inode->i_ino % 87 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) * 88 sizeof(struct efs_dinode); 89 90 bh = sb_bread(inode->i_sb, block); 91 if (!bh) { 92 printk(KERN_WARNING "EFS: bread() failed at block %d\n", block); 93 goto read_inode_error; 94 } 95 96 efs_inode = (struct efs_dinode *) (bh->b_data + offset); 97 98 inode->i_mode = be16_to_cpu(efs_inode->di_mode); 99 set_nlink(inode, be16_to_cpu(efs_inode->di_nlink)); 100 i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid)); 101 i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid)); 102 inode->i_size = be32_to_cpu(efs_inode->di_size); 103 inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime); 104 inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime); 105 inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime); 106 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0; 107 108 /* this is the number of blocks in the file */ 109 if (inode->i_size == 0) { 110 inode->i_blocks = 0; 111 } else { 112 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1; 113 } 114 115 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev); 116 if (rdev == 0xffff) { 117 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev); 118 if (sysv_major(rdev) > 0xfff) 119 device = 0; 120 else 121 device = MKDEV(sysv_major(rdev), sysv_minor(rdev)); 122 } else 123 device = old_decode_dev(rdev); 124 125 /* get the number of extents for this object */ 126 in->numextents = be16_to_cpu(efs_inode->di_numextents); 127 in->lastextent = 0; 128 129 /* copy the extents contained within the inode to memory */ 130 for(i = 0; i < EFS_DIRECTEXTENTS; i++) { 131 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i])); 132 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) { 133 printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino); 134 brelse(bh); 135 goto read_inode_error; 136 } 137 } 138 139 brelse(bh); 140 141 #ifdef DEBUG 142 printk(KERN_DEBUG "EFS: efs_iget(): inode %lu, extents %d, mode %o\n", 143 inode->i_ino, in->numextents, inode->i_mode); 144 #endif 145 146 switch (inode->i_mode & S_IFMT) { 147 case S_IFDIR: 148 inode->i_op = &efs_dir_inode_operations; 149 inode->i_fop = &efs_dir_operations; 150 break; 151 case S_IFREG: 152 inode->i_fop = &generic_ro_fops; 153 inode->i_data.a_ops = &efs_aops; 154 break; 155 case S_IFLNK: 156 inode->i_op = &page_symlink_inode_operations; 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 printk(KERN_WARNING "EFS: 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 printk(KERN_WARNING "EFS: 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 printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n"); 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 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block); 238 return 0; 239 } 240 241 #ifdef DEBUG 242 printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block); 243 #endif 244 direxts = in->extents[0].cooked.ex_offset; 245 indexts = in->numextents; 246 247 for(indext = 0; indext < indexts; indext++) { 248 cur = (last + indext) % indexts; 249 250 /* 251 * work out which direct extent contains `cur'. 252 * 253 * also compute ibase: i.e. the number of the first 254 * indirect extent contained within direct extent `cur'. 255 * 256 */ 257 ibase = 0; 258 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { 259 ibase += in->extents[dirext].cooked.ex_length * 260 (EFS_BLOCKSIZE / sizeof(efs_extent)); 261 } 262 263 if (dirext == direxts) { 264 /* should never happen */ 265 printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", 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 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock); 283 return 0; 284 } 285 #ifdef DEBUG 286 printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock); 287 #endif 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 printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock); 298 if (bh) brelse(bh); 299 return 0; 300 } 301 302 if ((result = efs_extent_check(&ext, block, sb))) { 303 if (bh) brelse(bh); 304 in->lastextent = cur; 305 return result; 306 } 307 } 308 if (bh) brelse(bh); 309 printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block); 310 return 0; 311 } 312 313 MODULE_LICENSE("GPL"); 314