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/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         .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 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 (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
 174 read_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
 180 static inline efs_block_t
 181 efs_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
 201 efs_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
 314 MODULE_LICENSE("GPL");