fs/efs/inode.c

   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/efs_fs.h>
  11 #include <linux/efs_fs_sb.h>
  12 #include <linux/buffer_head.h>
  13 #include <linux/module.h>
  14 #include <linux/fs.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         .sync_page = block_sync_page,
  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 void efs_read_inode(struct inode *inode)
  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(inode->i_sb);
  55         struct efs_inode_info *in = INODE_INFO(inode);
  56         efs_block_t block, offset;
  57         struct efs_dinode *efs_inode;
  58
  59         /*
  60         ** EFS layout:
  61         **
  62         ** |   cylinder group    |   cylinder group    |   cylinder group ..etc
  63         ** |inodes|data          |inodes|data          |inodes|data       ..etc
  64         **
  65         ** work out the inode block index, (considering initially that the
  66         ** inodes are stored as consecutive blocks). then work out the block
  67         ** number of that inode given the above layout, and finally the
  68         ** offset of the inode within that block.
  69         */
  70
  71         inode_index = inode->i_ino /
  72                 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
  73
  74         block = sb->fs_start + sb->first_block +
  75                 (sb->group_size * (inode_index / sb->inode_blocks)) +
  76                 (inode_index % sb->inode_blocks);
  77
  78         offset = (inode->i_ino %
  79                         (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
  80                 sizeof(struct efs_dinode);
  81
  82         bh = sb_bread(inode->i_sb, block);
  83         if (!bh) {
  84                 printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
  85                 goto read_inode_error;
  86         }
  87
  88         efs_inode = (struct efs_dinode *) (bh->b_data + offset);
  89
  90         inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
  91         inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
  92         inode->i_uid   = (uid_t)be16_to_cpu(efs_inode->di_uid);
  93         inode->i_gid   = (gid_t)be16_to_cpu(efs_inode->di_gid);
  94         inode->i_size  = be32_to_cpu(efs_inode->di_size);
  95         inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
  96         inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
  97         inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
  98         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
  99
 100         /* this is the number of blocks in the file */
 101         if (inode->i_size == 0) {
 102                 inode->i_blocks = 0;
 103         } else {
 104                 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
 105         }
 106
 107         rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
 108         if (rdev == 0xffff) {
 109                 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
 110                 if (sysv_major(rdev) > 0xfff)
 111                         device = 0;
 112                 else
 113                         device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
 114         } else
 115                 device = old_decode_dev(rdev);
 116
 117         /* get the number of extents for this object */
 118         in->numextents = be16_to_cpu(efs_inode->di_numextents);
 119         in->lastextent = 0;
 120
 121         /* copy the extents contained within the inode to memory */
 122         for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
 123                 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
 124                 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
 125                         printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino);
 126                         brelse(bh);
 127                         goto read_inode_error;
 128                 }
 129         }
 130
 131         brelse(bh);
 132
 133 #ifdef DEBUG
 134         printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
 135                 inode->i_ino, in->numextents, inode->i_mode);
 136 #endif
 137
 138         switch (inode->i_mode & S_IFMT) {
 139                 case S_IFDIR:
 140                         inode->i_op = &efs_dir_inode_operations;
 141                         inode->i_fop = &efs_dir_operations;
 142                         break;
 143                 case S_IFREG:
 144                         inode->i_fop = &generic_ro_fops;
 145                         inode->i_data.a_ops = &efs_aops;
 146                         break;
 147                 case S_IFLNK:
 148                         inode->i_op = &page_symlink_inode_operations;
 149                         inode->i_data.a_ops = &efs_symlink_aops;
 150                         break;
 151                 case S_IFCHR:
 152                 case S_IFBLK:
 153                 case S_IFIFO:
 154                         init_special_inode(inode, inode->i_mode, device);
 155                         break;
 156                 default:
 157                         printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
 158                         goto read_inode_error;
 159                         break;
 160         }
 161
 162         return;
 163
 164 read_inode_error:
 165         printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
 166         make_bad_inode(inode);
 167
 168         return;
 169 }
 170
 171 static inline efs_block_t
 172 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
 173         efs_block_t start;
 174         efs_block_t length;
 175         efs_block_t offset;
 176
 177         /*
 178          * given an extent and a logical block within a file,
 179          * can this block be found within this extent ?
 180          */
 181         start  = ptr->cooked.ex_bn;
 182         length = ptr->cooked.ex_length;
 183         offset = ptr->cooked.ex_offset;
 184
 185         if ((block >= offset) && (block < offset+length)) {
 186                 return(sb->fs_start + start + block - offset);
 187         } else {
 188                 return 0;
 189         }
 190 }
 191
 192 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
 193         struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
 194         struct efs_inode_info *in = INODE_INFO(inode);
 195         struct buffer_head    *bh = NULL;
 196
 197         int cur, last, first = 1;
 198         int ibase, ioffset, dirext, direxts, indext, indexts;
 199         efs_block_t iblock, result = 0, lastblock = 0;
 200         efs_extent ext, *exts;
 201
 202         last = in->lastextent;
 203
 204         if (in->numextents <= EFS_DIRECTEXTENTS) {
 205                 /* first check the last extent we returned */
 206                 if ((result = efs_extent_check(&in->extents[last], block, sb)))
 207                         return result;
 208
 209                 /* if we only have one extent then nothing can be found */
 210                 if (in->numextents == 1) {
 211                         printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n");
 212                         return 0;
 213                 }
 214
 215                 direxts = in->numextents;
 216
 217                 /*
 218                  * check the stored extents in the inode
 219                  * start with next extent and check forwards
 220                  */
 221                 for(dirext = 1; dirext < direxts; dirext++) {
 222                         cur = (last + dirext) % in->numextents;
 223                         if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
 224                                 in->lastextent = cur;
 225                                 return result;
 226                         }
 227                 }
 228
 229                 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
 230                 return 0;
 231         }
 232
 233 #ifdef DEBUG
 234         printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
 235 #endif
 236         direxts = in->extents[0].cooked.ex_offset;
 237         indexts = in->numextents;
 238
 239         for(indext = 0; indext < indexts; indext++) {
 240                 cur = (last + indext) % indexts;
 241
 242                 /*
 243                  * work out which direct extent contains `cur'.
 244                  *
 245                  * also compute ibase: i.e. the number of the first
 246                  * indirect extent contained within direct extent `cur'.
 247                  *
 248                  */
 249                 ibase = 0;
 250                 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
 251                         ibase += in->extents[dirext].cooked.ex_length *
 252                                 (EFS_BLOCKSIZE / sizeof(efs_extent));
 253                 }
 254
 255                 if (dirext == direxts) {
 256                         /* should never happen */
 257                         printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block);
 258                         if (bh) brelse(bh);
 259                         return 0;
 260                 }
 261
 262                 /* work out block number and offset of this indirect extent */
 263                 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
 264                         (cur - ibase) /
 265                         (EFS_BLOCKSIZE / sizeof(efs_extent));
 266                 ioffset = (cur - ibase) %
 267                         (EFS_BLOCKSIZE / sizeof(efs_extent));
 268
 269                 if (first || lastblock != iblock) {
 270                         if (bh) brelse(bh);
 271
 272                         bh = sb_bread(inode->i_sb, iblock);
 273                         if (!bh) {
 274                                 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
 275                                 return 0;
 276                         }
 277 #ifdef DEBUG
 278                         printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
 279 #endif
 280                         first = 0;
 281                         lastblock = iblock;
 282                 }
 283
 284                 exts = (efs_extent *) bh->b_data;
 285
 286                 extent_copy(&(exts[ioffset]), &ext);
 287
 288                 if (ext.cooked.ex_magic != 0) {
 289                         printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
 290                         if (bh) brelse(bh);
 291                         return 0;
 292                 }
 293
 294                 if ((result = efs_extent_check(&ext, block, sb))) {
 295                         if (bh) brelse(bh);
 296                         in->lastextent = cur;
 297                         return result;
 298                 }
 299         }
 300         if (bh) brelse(bh);
 301         printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
 302         return 0;
 303 }
 304
 305 MODULE_LICENSE("GPL");