inode.c 8.4 KB

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