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 <<<<<<< HEAD:fs/efs/inode.c
  11 #include <linux/efs_fs.h>
  12 #include <linux/efs_fs_sb.h>
  13 =======
  14 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:fs/efs/inode.c
  15 #include <linux/buffer_head.h>
  16 #include <linux/module.h>
  17 #include <linux/fs.h>
  18 <<<<<<< HEAD:fs/efs/inode.c
  19 =======
  20 #include "efs.h"
  21 #include <linux/efs_fs_sb.h>
  22 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:fs/efs/inode.c
  23
  24 static int efs_readpage(struct file *file, struct page *page)
  25 {
  26         return block_read_full_page(page,efs_get_block);
  27 }
  28 static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
  29 {
  30         return generic_block_bmap(mapping,block,efs_get_block);
  31 }
  32 static const struct address_space_operations efs_aops = {
  33         .readpage = efs_readpage,
  34         .sync_page = block_sync_page,
  35         .bmap = _efs_bmap
  36 };
  37
  38 static inline void extent_copy(efs_extent *src, efs_extent *dst) {
  39         /*
  40          * this is slightly evil. it doesn't just copy
  41          * efs_extent from src to dst, it also mangles
  42          * the bits so that dst ends up in cpu byte-order.
  43          */
  44
  45         dst->cooked.ex_magic  =  (unsigned int) src->raw[0];
  46         dst->cooked.ex_bn     = ((unsigned int) src->raw[1] << 16) |
  47                                 ((unsigned int) src->raw[2] <<  8) |
  48                                 ((unsigned int) src->raw[3] <<  0);
  49         dst->cooked.ex_length =  (unsigned int) src->raw[4];
  50         dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
  51                                 ((unsigned int) src->raw[6] <<  8) |
  52                                 ((unsigned int) src->raw[7] <<  0);
  53         return;
  54 }
  55
  56 struct inode *efs_iget(struct super_block *super, unsigned long ino)
  57 {
  58         int i, inode_index;
  59         dev_t device;
  60         u32 rdev;
  61         struct buffer_head *bh;
  62         struct efs_sb_info    *sb = SUPER_INFO(super);
  63         struct efs_inode_info *in;
  64         efs_block_t block, offset;
  65         struct efs_dinode *efs_inode;
  66         struct inode *inode;
  67
  68         inode = iget_locked(super, ino);
  69         if (IS_ERR(inode))
  70                 return ERR_PTR(-ENOMEM);
  71         if (!(inode->i_state & I_NEW))
  72                 return inode;
  73
  74         in = INODE_INFO(inode);
  75
  76         /*
  77         ** EFS layout:
  78         **
  79         ** |   cylinder group    |   cylinder group    |   cylinder group ..etc
  80         ** |inodes|data          |inodes|data          |inodes|data       ..etc
  81         **
  82         ** work out the inode block index, (considering initially that the
  83         ** inodes are stored as consecutive blocks). then work out the block
  84         ** number of that inode given the above layout, and finally the
  85         ** offset of the inode within that block.
  86         */
  87
  88         inode_index = inode->i_ino /
  89                 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
  90
  91         block = sb->fs_start + sb->first_block +
  92                 (sb->group_size * (inode_index / sb->inode_blocks)) +
  93                 (inode_index % sb->inode_blocks);
  94
  95         offset = (inode->i_ino %
  96                         (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
  97                 sizeof(struct efs_dinode);
  98
  99         bh = sb_bread(inode->i_sb, block);
 100         if (!bh) {
 101                 printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
 102                 goto read_inode_error;
 103         }
 104
 105         efs_inode = (struct efs_dinode *) (bh->b_data + offset);
 106
 107         inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
 108         inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
 109         inode->i_uid   = (uid_t)be16_to_cpu(efs_inode->di_uid);
 110         inode->i_gid   = (gid_t)be16_to_cpu(efs_inode->di_gid);
 111         inode->i_size  = be32_to_cpu(efs_inode->di_size);
 112         inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
 113         inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
 114         inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
 115         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
 116
 117         /* this is the number of blocks in the file */
 118         if (inode->i_size == 0) {
 119                 inode->i_blocks = 0;
 120         } else {
 121                 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
 122         }
 123
 124         rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
 125         if (rdev == 0xffff) {
 126                 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
 127                 if (sysv_major(rdev) > 0xfff)
 128                         device = 0;
 129                 else
 130                         device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
 131         } else
 132                 device = old_decode_dev(rdev);
 133
 134         /* get the number of extents for this object */
 135         in->numextents = be16_to_cpu(efs_inode->di_numextents);
 136         in->lastextent = 0;
 137
 138         /* copy the extents contained within the inode to memory */
 139         for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
 140                 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
 141                 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
 142                         printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino);
 143                         brelse(bh);
 144                         goto read_inode_error;
 145                 }
 146         }
 147
 148         brelse(bh);
 149
 150 #ifdef DEBUG
 151         printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
 152                 inode->i_ino, in->numextents, inode->i_mode);
 153 #endif
 154
 155         switch (inode->i_mode & S_IFMT) {
 156                 case S_IFDIR:
 157                         inode->i_op = &efs_dir_inode_operations;
 158                         inode->i_fop = &efs_dir_operations;
 159                         break;
 160                 case S_IFREG:
 161                         inode->i_fop = &generic_ro_fops;
 162                         inode->i_data.a_ops = &efs_aops;
 163                         break;
 164                 case S_IFLNK:
 165                         inode->i_op = &page_symlink_inode_operations;
 166                         inode->i_data.a_ops = &efs_symlink_aops;
 167                         break;
 168                 case S_IFCHR:
 169                 case S_IFBLK:
 170                 case S_IFIFO:
 171                         init_special_inode(inode, inode->i_mode, device);
 172                         break;
 173                 default:
 174                         printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
 175                         goto read_inode_error;
 176                         break;
 177         }
 178
 179         unlock_new_inode(inode);
 180         return inode;
 181
 182 read_inode_error:
 183         printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
 184         iget_failed(inode);
 185         return ERR_PTR(-EIO);
 186 }
 187
 188 static inline efs_block_t
 189 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
 190         efs_block_t start;
 191         efs_block_t length;
 192         efs_block_t offset;
 193
 194         /*
 195          * given an extent and a logical block within a file,
 196          * can this block be found within this extent ?
 197          */
 198         start  = ptr->cooked.ex_bn;
 199         length = ptr->cooked.ex_length;
 200         offset = ptr->cooked.ex_offset;
 201
 202         if ((block >= offset) && (block < offset+length)) {
 203                 return(sb->fs_start + start + block - offset);
 204         } else {
 205                 return 0;
 206         }
 207 }
 208
 209 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
 210         struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
 211         struct efs_inode_info *in = INODE_INFO(inode);
 212         struct buffer_head    *bh = NULL;
 213
 214         int cur, last, first = 1;
 215         int ibase, ioffset, dirext, direxts, indext, indexts;
 216         efs_block_t iblock, result = 0, lastblock = 0;
 217         efs_extent ext, *exts;
 218
 219         last = in->lastextent;
 220
 221         if (in->numextents <= EFS_DIRECTEXTENTS) {
 222                 /* first check the last extent we returned */
 223                 if ((result = efs_extent_check(&in->extents[last], block, sb)))
 224                         return result;
 225
 226                 /* if we only have one extent then nothing can be found */
 227                 if (in->numextents == 1) {
 228                         printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n");
 229                         return 0;
 230                 }
 231
 232                 direxts = in->numextents;
 233
 234                 /*
 235                  * check the stored extents in the inode
 236                  * start with next extent and check forwards
 237                  */
 238                 for(dirext = 1; dirext < direxts; dirext++) {
 239                         cur = (last + dirext) % in->numextents;
 240                         if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
 241                                 in->lastextent = cur;
 242                                 return result;
 243                         }
 244                 }
 245
 246                 printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
 247                 return 0;
 248         }
 249
 250 #ifdef DEBUG
 251         printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
 252 #endif
 253         direxts = in->extents[0].cooked.ex_offset;
 254         indexts = in->numextents;
 255
 256         for(indext = 0; indext < indexts; indext++) {
 257                 cur = (last + indext) % indexts;
 258
 259                 /*
 260                  * work out which direct extent contains `cur'.
 261                  *
 262                  * also compute ibase: i.e. the number of the first
 263                  * indirect extent contained within direct extent `cur'.
 264                  *
 265                  */
 266                 ibase = 0;
 267                 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
 268                         ibase += in->extents[dirext].cooked.ex_length *
 269                                 (EFS_BLOCKSIZE / sizeof(efs_extent));
 270                 }
 271
 272                 if (dirext == direxts) {
 273                         /* should never happen */
 274                         printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block);
 275                         if (bh) brelse(bh);
 276                         return 0;
 277                 }
 278
 279                 /* work out block number and offset of this indirect extent */
 280                 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
 281                         (cur - ibase) /
 282                         (EFS_BLOCKSIZE / sizeof(efs_extent));
 283                 ioffset = (cur - ibase) %
 284                         (EFS_BLOCKSIZE / sizeof(efs_extent));
 285
 286                 if (first || lastblock != iblock) {
 287                         if (bh) brelse(bh);
 288
 289                         bh = sb_bread(inode->i_sb, iblock);
 290                         if (!bh) {
 291                                 printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
 292                                 return 0;
 293                         }
 294 #ifdef DEBUG
 295                         printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
 296 #endif
 297                         first = 0;
 298                         lastblock = iblock;
 299                 }
 300
 301                 exts = (efs_extent *) bh->b_data;
 302
 303                 extent_copy(&(exts[ioffset]), &ext);
 304
 305                 if (ext.cooked.ex_magic != 0) {
 306                         printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
 307                         if (bh) brelse(bh);
 308                         return 0;
 309                 }
 310
 311                 if ((result = efs_extent_check(&ext, block, sb))) {
 312                         if (bh) brelse(bh);
 313                         in->lastextent = cur;
 314                         return result;
 315                 }
 316         }
 317         if (bh) brelse(bh);
 318         printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
 319         return 0;
 320 }
 321
 322 MODULE_LICENSE("GPL");