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