1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * inode.c 4 * 5 * Copyright (c) 1999 Al Smith 6 * 7 * Portions derived from work (c) 1995,1996 Christian Vogelgsang, 8 * and from work (c) 1998 Mike Shaver. 9 */ 10 11 #include <linux/buffer_head.h> 12 #include <linux/module.h> 13 #include <linux/fs.h> 14 #include "efs.h" 15 #include <linux/efs_fs_sb.h> 16 17 static int efs_readpage(struct file *file, struct page *page) 18 { 19 return block_read_full_page(page,efs_get_block); 20 } 21 static sector_t _efs_bmap(struct address_space *mapping, sector_t block) 22 { 23 return generic_block_bmap(mapping,block,efs_get_block); 24 } 25 static const struct address_space_operations efs_aops = { 26 .readpage = efs_readpage, 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 struct inode *efs_iget(struct super_block *super, unsigned long ino) 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(super); 55 struct efs_inode_info *in; 56 efs_block_t block, offset; 57 struct efs_dinode *efs_inode; 58 struct inode *inode; 59 60 inode = iget_locked(super, ino); 61 if (!inode) 62 return ERR_PTR(-ENOMEM); 63 if (!(inode->i_state & I_NEW)) 64 return inode; 65 66 in = INODE_INFO(inode); 67 68 /* 69 ** EFS layout: 70 ** 71 ** | cylinder group | cylinder group | cylinder group ..etc 72 ** |inodes|data |inodes|data |inodes|data ..etc 73 ** 74 ** work out the inode block index, (considering initially that the 75 ** inodes are stored as consecutive blocks). then work out the block 76 ** number of that inode given the above layout, and finally the 77 ** offset of the inode within that block. 78 */ 79 80 inode_index = inode->i_ino / 81 (EFS_BLOCKSIZE / sizeof(struct efs_dinode)); 82 83 block = sb->fs_start + sb->first_block + 84 (sb->group_size * (inode_index / sb->inode_blocks)) + 85 (inode_index % sb->inode_blocks); 86 87 offset = (inode->i_ino % 88 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) * 89 sizeof(struct efs_dinode); 90 91 bh = sb_bread(inode->i_sb, block); 92 if (!bh) { 93 pr_warn("%s() failed at block %d\n", __func__, block); 94 goto read_inode_error; 95 } 96 97 efs_inode = (struct efs_dinode *) (bh->b_data + offset); 98 99 inode->i_mode = be16_to_cpu(efs_inode->di_mode); 100 set_nlink(inode, be16_to_cpu(efs_inode->di_nlink)); 101 i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid)); 102 i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid)); 103 inode->i_size = be32_to_cpu(efs_inode->di_size); 104 inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime); 105 inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime); 106 inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime); 107 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0; 108 109 /* this is the number of blocks in the file */ 110 if (inode->i_size == 0) { 111 inode->i_blocks = 0; 112 } else { 113 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1; 114 } 115 116 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev); 117 if (rdev == 0xffff) { 118 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev); 119 if (sysv_major(rdev) > 0xfff) 120 device = 0; 121 else 122 device = MKDEV(sysv_major(rdev), sysv_minor(rdev)); 123 } else 124 device = old_decode_dev(rdev); 125 126 /* get the number of extents for this object */ 127 in->numextents = be16_to_cpu(efs_inode->di_numextents); 128 in->lastextent = 0; 129 130 /* copy the extents contained within the inode to memory */ 131 for(i = 0; i < EFS_DIRECTEXTENTS; i++) { 132 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i])); 133 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) { 134 pr_warn("extent %d has bad magic number in inode %lu\n", 135 i, inode->i_ino); 136 brelse(bh); 137 goto read_inode_error; 138 } 139 } 140 141 brelse(bh); 142 pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n", 143 inode->i_ino, in->numextents, inode->i_mode); 144 switch (inode->i_mode & S_IFMT) { 145 case S_IFDIR: 146 inode->i_op = &efs_dir_inode_operations; 147 inode->i_fop = &efs_dir_operations; 148 break; 149 case S_IFREG: 150 inode->i_fop = &generic_ro_fops; 151 inode->i_data.a_ops = &efs_aops; 152 break; 153 case S_IFLNK: 154 inode->i_op = &page_symlink_inode_operations; 155 inode_nohighmem(inode); 156 inode->i_data.a_ops = &efs_symlink_aops; 157 break; 158 case S_IFCHR: 159 case S_IFBLK: 160 case S_IFIFO: 161 init_special_inode(inode, inode->i_mode, device); 162 break; 163 default: 164 pr_warn("unsupported inode mode %o\n", inode->i_mode); 165 goto read_inode_error; 166 break; 167 } 168 169 unlock_new_inode(inode); 170 return inode; 171 172 read_inode_error: 173 pr_warn("failed to read inode %lu\n", inode->i_ino); 174 iget_failed(inode); 175 return ERR_PTR(-EIO); 176 } 177 178 static inline efs_block_t 179 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) { 180 efs_block_t start; 181 efs_block_t length; 182 efs_block_t offset; 183 184 /* 185 * given an extent and a logical block within a file, 186 * can this block be found within this extent ? 187 */ 188 start = ptr->cooked.ex_bn; 189 length = ptr->cooked.ex_length; 190 offset = ptr->cooked.ex_offset; 191 192 if ((block >= offset) && (block < offset+length)) { 193 return(sb->fs_start + start + block - offset); 194 } else { 195 return 0; 196 } 197 } 198 199 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) { 200 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb); 201 struct efs_inode_info *in = INODE_INFO(inode); 202 struct buffer_head *bh = NULL; 203 204 int cur, last, first = 1; 205 int ibase, ioffset, dirext, direxts, indext, indexts; 206 efs_block_t iblock, result = 0, lastblock = 0; 207 efs_extent ext, *exts; 208 209 last = in->lastextent; 210 211 if (in->numextents <= EFS_DIRECTEXTENTS) { 212 /* first check the last extent we returned */ 213 if ((result = efs_extent_check(&in->extents[last], block, sb))) 214 return result; 215 216 /* if we only have one extent then nothing can be found */ 217 if (in->numextents == 1) { 218 pr_err("%s() failed to map (1 extent)\n", __func__); 219 return 0; 220 } 221 222 direxts = in->numextents; 223 224 /* 225 * check the stored extents in the inode 226 * start with next extent and check forwards 227 */ 228 for(dirext = 1; dirext < direxts; dirext++) { 229 cur = (last + dirext) % in->numextents; 230 if ((result = efs_extent_check(&in->extents[cur], block, sb))) { 231 in->lastextent = cur; 232 return result; 233 } 234 } 235 236 pr_err("%s() failed to map block %u (dir)\n", __func__, block); 237 return 0; 238 } 239 240 pr_debug("%s(): indirect search for logical block %u\n", 241 __func__, block); 242 direxts = in->extents[0].cooked.ex_offset; 243 indexts = in->numextents; 244 245 for(indext = 0; indext < indexts; indext++) { 246 cur = (last + indext) % indexts; 247 248 /* 249 * work out which direct extent contains `cur'. 250 * 251 * also compute ibase: i.e. the number of the first 252 * indirect extent contained within direct extent `cur'. 253 * 254 */ 255 ibase = 0; 256 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { 257 ibase += in->extents[dirext].cooked.ex_length * 258 (EFS_BLOCKSIZE / sizeof(efs_extent)); 259 } 260 261 if (dirext == direxts) { 262 /* should never happen */ 263 pr_err("couldn't find direct extent for indirect extent %d (block %u)\n", 264 cur, block); 265 if (bh) brelse(bh); 266 return 0; 267 } 268 269 /* work out block number and offset of this indirect extent */ 270 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn + 271 (cur - ibase) / 272 (EFS_BLOCKSIZE / sizeof(efs_extent)); 273 ioffset = (cur - ibase) % 274 (EFS_BLOCKSIZE / sizeof(efs_extent)); 275 276 if (first || lastblock != iblock) { 277 if (bh) brelse(bh); 278 279 bh = sb_bread(inode->i_sb, iblock); 280 if (!bh) { 281 pr_err("%s() failed at block %d\n", 282 __func__, iblock); 283 return 0; 284 } 285 pr_debug("%s(): read indirect extent block %d\n", 286 __func__, iblock); 287 first = 0; 288 lastblock = iblock; 289 } 290 291 exts = (efs_extent *) bh->b_data; 292 293 extent_copy(&(exts[ioffset]), &ext); 294 295 if (ext.cooked.ex_magic != 0) { 296 pr_err("extent %d has bad magic number in block %d\n", 297 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 pr_err("%s() failed to map block %u (indir)\n", __func__, block); 310 return 0; 311 } 312 313 MODULE_LICENSE("GPL"); 314