symlink.c 1.9 KB

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  1. /*
  2. * JFFS2 -- Journalling Flash File System, Version 2.
  3. *
  4. * Copyright (C) 2001, 2002 Red Hat, Inc.
  5. *
  6. * Created by David Woodhouse <dwmw2@infradead.org>
  7. *
  8. * For licensing information, see the file 'LICENCE' in this directory.
  9. *
  10. * $Id: symlink.c,v 1.1.1.1 2007/06/12 07:27:13 eyryu Exp $
  11. *
  12. */
  13. #include <linux/kernel.h>
  14. #include <linux/slab.h>
  15. #include <linux/fs.h>
  16. #include <linux/namei.h>
  17. #include "nodelist.h"
  18. static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
  19. const struct inode_operations jffs2_symlink_inode_operations =
  20. {
  21. .readlink = generic_readlink,
  22. .follow_link = jffs2_follow_link,
  23. .permission = jffs2_permission,
  24. .setattr = jffs2_setattr,
  25. .setxattr = jffs2_setxattr,
  26. .getxattr = jffs2_getxattr,
  27. .listxattr = jffs2_listxattr,
  28. .removexattr = jffs2_removexattr
  29. };
  30. static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
  31. {
  32. struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
  33. char *p = (char *)f->target;
  34. /*
  35. * We don't acquire the f->sem mutex here since the only data we
  36. * use is f->target.
  37. *
  38. * 1. If we are here the inode has already built and f->target has
  39. * to point to the target path.
  40. * 2. Nobody uses f->target (if the inode is symlink's inode). The
  41. * exception is inode freeing function which frees f->target. But
  42. * it can't be called while we are here and before VFS has
  43. * stopped using our f->target string which we provide by means of
  44. * nd_set_link() call.
  45. */
  46. if (!p) {
  47. printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n");
  48. p = ERR_PTR(-EIO);
  49. }
  50. D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->target));
  51. nd_set_link(nd, p);
  52. /*
  53. * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe
  54. * since the only way that may cause f->target to be changed is iput() operation.
  55. * But VFS will not use f->target after iput() has been called.
  56. */
  57. return NULL;
  58. }