inode.c 8.5 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * inode.c
  4. *
  5. * Copyright (c) 1999 Al Smith
  6. *
  7. * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
  8. * and from work (c) 1998 Mike Shaver.
  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. static int efs_readpage(struct file *file, struct page *page)
  16. {
  17. return block_read_full_page(page,efs_get_block);
  18. }
  19. static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
  20. {
  21. return generic_block_bmap(mapping,block,efs_get_block);
  22. }
  23. static const struct address_space_operations efs_aops = {
  24. .readpage = efs_readpage,
  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. struct inode *efs_iget(struct super_block *super, unsigned long ino)
  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(super);
  50. struct efs_inode_info *in;
  51. efs_block_t block, offset;
  52. struct efs_dinode *efs_inode;
  53. struct inode *inode;
  54. inode = iget_locked(super, ino);
  55. if (!inode)
  56. return ERR_PTR(-ENOMEM);
  57. if (!(inode->i_state & I_NEW))
  58. return inode;
  59. in = INODE_INFO(inode);
  60. /*
  61. ** EFS layout:
  62. **
  63. ** | cylinder group | cylinder group | cylinder group ..etc
  64. ** |inodes|data |inodes|data |inodes|data ..etc
  65. **
  66. ** work out the inode block index, (considering initially that the
  67. ** inodes are stored as consecutive blocks). then work out the block
  68. ** number of that inode given the above layout, and finally the
  69. ** offset of the inode within that block.
  70. */
  71. inode_index = inode->i_ino /
  72. (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
  73. block = sb->fs_start + sb->first_block +
  74. (sb->group_size * (inode_index / sb->inode_blocks)) +
  75. (inode_index % sb->inode_blocks);
  76. offset = (inode->i_ino %
  77. (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
  78. sizeof(struct efs_dinode);
  79. bh = sb_bread(inode->i_sb, block);
  80. if (!bh) {
  81. pr_warn("%s() failed at block %d\n", __func__, block);
  82. goto read_inode_error;
  83. }
  84. efs_inode = (struct efs_dinode *) (bh->b_data + offset);
  85. inode->i_mode = be16_to_cpu(efs_inode->di_mode);
  86. set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
  87. i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
  88. i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
  89. inode->i_size = be32_to_cpu(efs_inode->di_size);
  90. inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
  91. inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
  92. inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
  93. inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
  94. /* this is the number of blocks in the file */
  95. if (inode->i_size == 0) {
  96. inode->i_blocks = 0;
  97. } else {
  98. inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
  99. }
  100. rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
  101. if (rdev == 0xffff) {
  102. rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
  103. if (sysv_major(rdev) > 0xfff)
  104. device = 0;
  105. else
  106. device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
  107. } else
  108. device = old_decode_dev(rdev);
  109. /* get the number of extents for this object */
  110. in->numextents = be16_to_cpu(efs_inode->di_numextents);
  111. in->lastextent = 0;
  112. /* copy the extents contained within the inode to memory */
  113. for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
  114. extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
  115. if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
  116. pr_warn("extent %d has bad magic number in inode %lu\n",
  117. i, inode->i_ino);
  118. brelse(bh);
  119. goto read_inode_error;
  120. }
  121. }
  122. brelse(bh);
  123. pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
  124. inode->i_ino, in->numextents, inode->i_mode);
  125. switch (inode->i_mode & S_IFMT) {
  126. case S_IFDIR:
  127. inode->i_op = &efs_dir_inode_operations;
  128. inode->i_fop = &efs_dir_operations;
  129. break;
  130. case S_IFREG:
  131. inode->i_fop = &generic_ro_fops;
  132. inode->i_data.a_ops = &efs_aops;
  133. break;
  134. case S_IFLNK:
  135. inode->i_op = &page_symlink_inode_operations;
  136. inode_nohighmem(inode);
  137. inode->i_data.a_ops = &efs_symlink_aops;
  138. break;
  139. case S_IFCHR:
  140. case S_IFBLK:
  141. case S_IFIFO:
  142. init_special_inode(inode, inode->i_mode, device);
  143. break;
  144. default:
  145. pr_warn("unsupported inode mode %o\n", inode->i_mode);
  146. goto read_inode_error;
  147. break;
  148. }
  149. unlock_new_inode(inode);
  150. return inode;
  151. read_inode_error:
  152. pr_warn("failed to read inode %lu\n", inode->i_ino);
  153. iget_failed(inode);
  154. return ERR_PTR(-EIO);
  155. }
  156. static inline efs_block_t
  157. efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
  158. efs_block_t start;
  159. efs_block_t length;
  160. efs_block_t offset;
  161. /*
  162. * given an extent and a logical block within a file,
  163. * can this block be found within this extent ?
  164. */
  165. start = ptr->cooked.ex_bn;
  166. length = ptr->cooked.ex_length;
  167. offset = ptr->cooked.ex_offset;
  168. if ((block >= offset) && (block < offset+length)) {
  169. return(sb->fs_start + start + block - offset);
  170. } else {
  171. return 0;
  172. }
  173. }
  174. efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
  175. struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
  176. struct efs_inode_info *in = INODE_INFO(inode);
  177. struct buffer_head *bh = NULL;
  178. int cur, last, first = 1;
  179. int ibase, ioffset, dirext, direxts, indext, indexts;
  180. efs_block_t iblock, result = 0, lastblock = 0;
  181. efs_extent ext, *exts;
  182. last = in->lastextent;
  183. if (in->numextents <= EFS_DIRECTEXTENTS) {
  184. /* first check the last extent we returned */
  185. if ((result = efs_extent_check(&in->extents[last], block, sb)))
  186. return result;
  187. /* if we only have one extent then nothing can be found */
  188. if (in->numextents == 1) {
  189. pr_err("%s() failed to map (1 extent)\n", __func__);
  190. return 0;
  191. }
  192. direxts = in->numextents;
  193. /*
  194. * check the stored extents in the inode
  195. * start with next extent and check forwards
  196. */
  197. for(dirext = 1; dirext < direxts; dirext++) {
  198. cur = (last + dirext) % in->numextents;
  199. if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
  200. in->lastextent = cur;
  201. return result;
  202. }
  203. }
  204. pr_err("%s() failed to map block %u (dir)\n", __func__, block);
  205. return 0;
  206. }
  207. pr_debug("%s(): indirect search for logical block %u\n",
  208. __func__, block);
  209. direxts = in->extents[0].cooked.ex_offset;
  210. indexts = in->numextents;
  211. for(indext = 0; indext < indexts; indext++) {
  212. cur = (last + indext) % indexts;
  213. /*
  214. * work out which direct extent contains `cur'.
  215. *
  216. * also compute ibase: i.e. the number of the first
  217. * indirect extent contained within direct extent `cur'.
  218. *
  219. */
  220. ibase = 0;
  221. for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
  222. ibase += in->extents[dirext].cooked.ex_length *
  223. (EFS_BLOCKSIZE / sizeof(efs_extent));
  224. }
  225. if (dirext == direxts) {
  226. /* should never happen */
  227. pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
  228. cur, block);
  229. if (bh) brelse(bh);
  230. return 0;
  231. }
  232. /* work out block number and offset of this indirect extent */
  233. iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
  234. (cur - ibase) /
  235. (EFS_BLOCKSIZE / sizeof(efs_extent));
  236. ioffset = (cur - ibase) %
  237. (EFS_BLOCKSIZE / sizeof(efs_extent));
  238. if (first || lastblock != iblock) {
  239. if (bh) brelse(bh);
  240. bh = sb_bread(inode->i_sb, iblock);
  241. if (!bh) {
  242. pr_err("%s() failed at block %d\n",
  243. __func__, iblock);
  244. return 0;
  245. }
  246. pr_debug("%s(): read indirect extent block %d\n",
  247. __func__, iblock);
  248. first = 0;
  249. lastblock = iblock;
  250. }
  251. exts = (efs_extent *) bh->b_data;
  252. extent_copy(&(exts[ioffset]), &ext);
  253. if (ext.cooked.ex_magic != 0) {
  254. pr_err("extent %d has bad magic number in block %d\n",
  255. cur, iblock);
  256. if (bh) brelse(bh);
  257. return 0;
  258. }
  259. if ((result = efs_extent_check(&ext, block, sb))) {
  260. if (bh) brelse(bh);
  261. in->lastextent = cur;
  262. return result;
  263. }
  264. }
  265. if (bh) brelse(bh);
  266. pr_err("%s() failed to map block %u (indir)\n", __func__, block);
  267. return 0;
  268. }
  269. MODULE_LICENSE("GPL");
  270. MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);