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