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 pr_warn("%s() failed at block %d\n", __func__, 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 pr_warn("extent %d has bad magic number in inode %lu\n", 134 i, inode->i_ino); 135 brelse(bh); 136 goto read_inode_error; 137 } 138 } 139 140 brelse(bh); 141 142 #ifdef DEBUG 143 printk(KERN_DEBUG "EFS: efs_iget(): inode %lu, extents %d, mode %o\n", 144 inode->i_ino, in->numextents, inode->i_mode); 145 #endif 146 147 switch (inode->i_mode & S_IFMT) { 148 case S_IFDIR: 149 inode->i_op = &efs_dir_inode_operations; 150 inode->i_fop = &efs_dir_operations; 151 break; 152 case S_IFREG: 153 inode->i_fop = &generic_ro_fops; 154 inode->i_data.a_ops = &efs_aops; 155 break; 156 case S_IFLNK: 157 inode->i_op = &page_symlink_inode_operations; 158 inode->i_data.a_ops = &efs_symlink_aops; 159 break; 160 case S_IFCHR: 161 case S_IFBLK: 162 case S_IFIFO: 163 init_special_inode(inode, inode->i_mode, device); 164 break; 165 default: 166 pr_warn("unsupported inode mode %o\n", inode->i_mode); 167 goto read_inode_error; 168 break; 169 } 170 171 unlock_new_inode(inode); 172 return inode; 173 174 read_inode_error: 175 pr_warn("failed to read inode %lu\n", inode->i_ino); 176 iget_failed(inode); 177 return ERR_PTR(-EIO); 178 } 179 180 static inline efs_block_t 181 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) { 182 efs_block_t start; 183 efs_block_t length; 184 efs_block_t offset; 185 186 /* 187 * given an extent and a logical block within a file, 188 * can this block be found within this extent ? 189 */ 190 start = ptr->cooked.ex_bn; 191 length = ptr->cooked.ex_length; 192 offset = ptr->cooked.ex_offset; 193 194 if ((block >= offset) && (block < offset+length)) { 195 return(sb->fs_start + start + block - offset); 196 } else { 197 return 0; 198 } 199 } 200 201 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) { 202 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb); 203 struct efs_inode_info *in = INODE_INFO(inode); 204 struct buffer_head *bh = NULL; 205 206 int cur, last, first = 1; 207 int ibase, ioffset, dirext, direxts, indext, indexts; 208 efs_block_t iblock, result = 0, lastblock = 0; 209 efs_extent ext, *exts; 210 211 last = in->lastextent; 212 213 if (in->numextents <= EFS_DIRECTEXTENTS) { 214 /* first check the last extent we returned */ 215 if ((result = efs_extent_check(&in->extents[last], block, sb))) 216 return result; 217 218 /* if we only have one extent then nothing can be found */ 219 if (in->numextents == 1) { 220 pr_err("%s() failed to map (1 extent)\n", __func__); 221 return 0; 222 } 223 224 direxts = in->numextents; 225 226 /* 227 * check the stored extents in the inode 228 * start with next extent and check forwards 229 */ 230 for(dirext = 1; dirext < direxts; dirext++) { 231 cur = (last + dirext) % in->numextents; 232 if ((result = efs_extent_check(&in->extents[cur], block, sb))) { 233 in->lastextent = cur; 234 return result; 235 } 236 } 237 238 pr_err("%s() failed to map block %u (dir)\n", __func__, block); 239 return 0; 240 } 241 242 #ifdef DEBUG 243 printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block); 244 #endif 245 direxts = in->extents[0].cooked.ex_offset; 246 indexts = in->numextents; 247 248 for(indext = 0; indext < indexts; indext++) { 249 cur = (last + indext) % indexts; 250 251 /* 252 * work out which direct extent contains `cur'. 253 * 254 * also compute ibase: i.e. the number of the first 255 * indirect extent contained within direct extent `cur'. 256 * 257 */ 258 ibase = 0; 259 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { 260 ibase += in->extents[dirext].cooked.ex_length * 261 (EFS_BLOCKSIZE / sizeof(efs_extent)); 262 } 263 264 if (dirext == direxts) { 265 /* should never happen */ 266 pr_err("couldn't find direct extent for indirect extent %d (block %u)\n", 267 cur, block); 268 if (bh) brelse(bh); 269 return 0; 270 } 271 272 /* work out block number and offset of this indirect extent */ 273 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn + 274 (cur - ibase) / 275 (EFS_BLOCKSIZE / sizeof(efs_extent)); 276 ioffset = (cur - ibase) % 277 (EFS_BLOCKSIZE / sizeof(efs_extent)); 278 279 if (first || lastblock != iblock) { 280 if (bh) brelse(bh); 281 282 bh = sb_bread(inode->i_sb, iblock); 283 if (!bh) { 284 pr_err("%s() failed at block %d\n", 285 __func__, iblock); 286 return 0; 287 } 288 #ifdef DEBUG 289 printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock); 290 #endif 291 first = 0; 292 lastblock = iblock; 293 } 294 295 exts = (efs_extent *) bh->b_data; 296 297 extent_copy(&(exts[ioffset]), &ext); 298 299 if (ext.cooked.ex_magic != 0) { 300 pr_err("extent %d has bad magic number in block %d\n", 301 cur, iblock); 302 if (bh) brelse(bh); 303 return 0; 304 } 305 306 if ((result = efs_extent_check(&ext, block, sb))) { 307 if (bh) brelse(bh); 308 in->lastextent = cur; 309 return result; 310 } 311 } 312 if (bh) brelse(bh); 313 pr_err("%s() failed to map block %u (indir)\n", __func__, block); 314 return 0; 315 } 316 317 MODULE_LICENSE("GPL"); 318