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