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_read_folio(struct file *file, struct folio *folio) 18 { 19 return block_read_full_folio(folio, efs_get_block); 20 } 21 22 static sector_t _efs_bmap(struct address_space *mapping, sector_t block) 23 { 24 return generic_block_bmap(mapping,block,efs_get_block); 25 } 26 27 static const struct address_space_operations efs_aops = { 28 .read_folio = efs_read_folio, 29 .bmap = _efs_bmap 30 }; 31 32 static inline void extent_copy(efs_extent *src, efs_extent *dst) { 33 /* 34 * this is slightly evil. it doesn't just copy 35 * efs_extent from src to dst, it also mangles 36 * the bits so that dst ends up in cpu byte-order. 37 */ 38 39 dst->cooked.ex_magic = (unsigned int) src->raw[0]; 40 dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) | 41 ((unsigned int) src->raw[2] << 8) | 42 ((unsigned int) src->raw[3] << 0); 43 dst->cooked.ex_length = (unsigned int) src->raw[4]; 44 dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) | 45 ((unsigned int) src->raw[6] << 8) | 46 ((unsigned int) src->raw[7] << 0); 47 return; 48 } 49 50 struct inode *efs_iget(struct super_block *super, unsigned long ino) 51 { 52 int i, inode_index; 53 dev_t device; 54 u32 rdev; 55 struct buffer_head *bh; 56 struct efs_sb_info *sb = SUPER_INFO(super); 57 struct efs_inode_info *in; 58 efs_block_t block, offset; 59 struct efs_dinode *efs_inode; 60 struct inode *inode; 61 62 inode = iget_locked(super, ino); 63 if (!inode) 64 return ERR_PTR(-ENOMEM); 65 if (!(inode->i_state & I_NEW)) 66 return inode; 67 68 in = INODE_INFO(inode); 69 70 /* 71 ** EFS layout: 72 ** 73 ** | cylinder group | cylinder group | cylinder group ..etc 74 ** |inodes|data |inodes|data |inodes|data ..etc 75 ** 76 ** work out the inode block index, (considering initially that the 77 ** inodes are stored as consecutive blocks). then work out the block 78 ** number of that inode given the above layout, and finally the 79 ** offset of the inode within that block. 80 */ 81 82 inode_index = inode->i_ino / 83 (EFS_BLOCKSIZE / sizeof(struct efs_dinode)); 84 85 block = sb->fs_start + sb->first_block + 86 (sb->group_size * (inode_index / sb->inode_blocks)) + 87 (inode_index % sb->inode_blocks); 88 89 offset = (inode->i_ino % 90 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) * 91 sizeof(struct efs_dinode); 92 93 bh = sb_bread(inode->i_sb, block); 94 if (!bh) { 95 pr_warn("%s() failed at block %d\n", __func__, block); 96 goto read_inode_error; 97 } 98 99 efs_inode = (struct efs_dinode *) (bh->b_data + offset); 100 101 inode->i_mode = be16_to_cpu(efs_inode->di_mode); 102 set_nlink(inode, be16_to_cpu(efs_inode->di_nlink)); 103 i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid)); 104 i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid)); 105 inode->i_size = be32_to_cpu(efs_inode->di_size); 106 inode_set_atime(inode, be32_to_cpu(efs_inode->di_atime), 0); 107 inode_set_mtime(inode, be32_to_cpu(efs_inode->di_mtime), 0); 108 inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 0); 109 110 /* this is the number of blocks in the file */ 111 if (inode->i_size == 0) { 112 inode->i_blocks = 0; 113 } else { 114 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1; 115 } 116 117 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev); 118 if (rdev == 0xffff) { 119 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev); 120 if (sysv_major(rdev) > 0xfff) 121 device = 0; 122 else 123 device = MKDEV(sysv_major(rdev), sysv_minor(rdev)); 124 } else 125 device = old_decode_dev(rdev); 126 127 /* get the number of extents for this object */ 128 in->numextents = be16_to_cpu(efs_inode->di_numextents); 129 in->lastextent = 0; 130 131 /* copy the extents contained within the inode to memory */ 132 for(i = 0; i < EFS_DIRECTEXTENTS; i++) { 133 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i])); 134 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) { 135 pr_warn("extent %d has bad magic number in inode %lu\n", 136 i, inode->i_ino); 137 brelse(bh); 138 goto read_inode_error; 139 } 140 } 141 142 brelse(bh); 143 pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n", 144 inode->i_ino, in->numextents, inode->i_mode); 145 switch (inode->i_mode & S_IFMT) { 146 case S_IFDIR: 147 inode->i_op = &efs_dir_inode_operations; 148 inode->i_fop = &efs_dir_operations; 149 break; 150 case S_IFREG: 151 inode->i_fop = &generic_ro_fops; 152 inode->i_data.a_ops = &efs_aops; 153 break; 154 case S_IFLNK: 155 inode->i_op = &page_symlink_inode_operations; 156 inode_nohighmem(inode); 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 pr_warn("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 pr_warn("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 pr_err("%s() failed to map (1 extent)\n", __func__); 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 pr_err("%s() failed to map block %u (dir)\n", __func__, block); 238 return 0; 239 } 240 241 pr_debug("%s(): indirect search for logical block %u\n", 242 __func__, block); 243 direxts = in->extents[0].cooked.ex_offset; 244 indexts = in->numextents; 245 246 for(indext = 0; indext < indexts; indext++) { 247 cur = (last + indext) % indexts; 248 249 /* 250 * work out which direct extent contains `cur'. 251 * 252 * also compute ibase: i.e. the number of the first 253 * indirect extent contained within direct extent `cur'. 254 * 255 */ 256 ibase = 0; 257 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { 258 ibase += in->extents[dirext].cooked.ex_length * 259 (EFS_BLOCKSIZE / sizeof(efs_extent)); 260 } 261 262 if (dirext == direxts) { 263 /* should never happen */ 264 pr_err("couldn't find direct extent for indirect extent %d (block %u)\n", 265 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 pr_err("%s() failed at block %d\n", 283 __func__, iblock); 284 return 0; 285 } 286 pr_debug("%s(): read indirect extent block %d\n", 287 __func__, iblock); 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 pr_err("extent %d has bad magic number in block %d\n", 298 cur, iblock); 299 if (bh) brelse(bh); 300 return 0; 301 } 302 303 if ((result = efs_extent_check(&ext, block, sb))) { 304 if (bh) brelse(bh); 305 in->lastextent = cur; 306 return result; 307 } 308 } 309 if (bh) brelse(bh); 310 pr_err("%s() failed to map block %u (indir)\n", __func__, block); 311 return 0; 312 } 313 314 MODULE_LICENSE("GPL"); 315