symlink.c 1.8 KB

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  1. /*
  2. * linux/fs/nfs/symlink.c
  3. *
  4. * Copyright (C) 1992 Rick Sladkey
  5. *
  6. * Optimization changes Copyright (C) 1994 Florian La Roche
  7. *
  8. * Jun 7 1999, cache symlink lookups in the page cache. -DaveM
  9. *
  10. * nfs symlink handling code
  11. */
  12. #define NFS_NEED_XDR_TYPES
  13. #include <linux/time.h>
  14. #include <linux/errno.h>
  15. #include <linux/sunrpc/clnt.h>
  16. #include <linux/nfs.h>
  17. #include <linux/nfs2.h>
  18. #include <linux/nfs_fs.h>
  19. #include <linux/pagemap.h>
  20. #include <linux/stat.h>
  21. #include <linux/mm.h>
  22. #include <linux/slab.h>
  23. #include <linux/string.h>
  24. #include <linux/smp_lock.h>
  25. #include <linux/namei.h>
  26. /* Symlink caching in the page cache is even more simplistic
  27. * and straight-forward than readdir caching.
  28. */
  29. static int nfs_symlink_filler(struct inode *inode, struct page *page)
  30. {
  31. int error;
  32. error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
  33. if (error < 0)
  34. goto error;
  35. SetPageUptodate(page);
  36. unlock_page(page);
  37. return 0;
  38. error:
  39. SetPageError(page);
  40. unlock_page(page);
  41. return -EIO;
  42. }
  43. static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
  44. {
  45. struct inode *inode = dentry->d_inode;
  46. struct page *page;
  47. void *err;
  48. err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping));
  49. if (err)
  50. goto read_failed;
  51. page = read_cache_page(&inode->i_data, 0,
  52. (filler_t *)nfs_symlink_filler, inode);
  53. if (IS_ERR(page)) {
  54. err = page;
  55. goto read_failed;
  56. }
  57. if (!PageUptodate(page)) {
  58. err = ERR_PTR(-EIO);
  59. goto getlink_read_error;
  60. }
  61. nd_set_link(nd, kmap(page));
  62. return page;
  63. getlink_read_error:
  64. page_cache_release(page);
  65. read_failed:
  66. nd_set_link(nd, err);
  67. return NULL;
  68. }
  69. /*
  70. * symlinks can't do much...
  71. */
  72. const struct inode_operations nfs_symlink_inode_operations = {
  73. .readlink = generic_readlink,
  74. .follow_link = nfs_follow_link,
  75. .put_link = page_put_link,
  76. .getattr = nfs_getattr,
  77. .setattr = nfs_setattr,
  78. };