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 16static int efs_readpage(struct file *file, struct page *page) 17{ 18 return block_read_full_page(page,efs_get_block); 19} 20static sector_t _efs_bmap(struct address_space *mapping, sector_t block) 21{ 22 return generic_block_bmap(mapping,block,efs_get_block); 23} 24static const struct address_space_operations efs_aops = { 25 .readpage = efs_readpage, 26 .sync_page = block_sync_page, 27 .bmap = _efs_bmap 28}; 29 30static 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 48struct 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 (IS_ERR(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 printk(KERN_WARNING "EFS: bread() failed at block %d\n", 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 inode->i_nlink = be16_to_cpu(efs_inode->di_nlink); 101 inode->i_uid = (uid_t)be16_to_cpu(efs_inode->di_uid); 102 inode->i_gid = (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 printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", 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 printk(KERN_WARNING "EFS: 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 174read_inode_error: 175 printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino); 176 iget_failed(inode); 177 return ERR_PTR(-EIO); 178} 179 180static inline efs_block_t 181efs_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 201efs_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 printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n"); 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 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", 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 printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block); 267 if (bh) brelse(bh); 268 return 0; 269 } 270 271 /* work out block number and offset of this indirect extent */ 272 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn + 273 (cur - ibase) / 274 (EFS_BLOCKSIZE / sizeof(efs_extent)); 275 ioffset = (cur - ibase) % 276 (EFS_BLOCKSIZE / sizeof(efs_extent)); 277 278 if (first || lastblock != iblock) { 279 if (bh) brelse(bh); 280 281 bh = sb_bread(inode->i_sb, iblock); 282 if (!bh) { 283 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock); 284 return 0; 285 } 286#ifdef DEBUG 287 printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock); 288#endif 289 first = 0; 290 lastblock = iblock; 291 } 292 293 exts = (efs_extent *) bh->b_data; 294 295 extent_copy(&(exts[ioffset]), &ext); 296 297 if (ext.cooked.ex_magic != 0) { 298 printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", 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 printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block); 311 return 0; 312} 313 314MODULE_LICENSE("GPL"); 315