[PATCH] fix-sysfs-symlinks.patch

[PATCH] fix-sysfs-symlinks.patch

- Rediffed the patch for 2.6.6-mm3 to fix rejects in the latest changes
  in sysfs code.

o The symlinks code in sysfs doesnot point to the correct target kobject
  whenever target kobject is renamed and suffers from dangling symlinks
  if target kobject is removed.

o The following patch implements ->readlink and ->follow_link operations
  for sysfs instead of using the page_symlink_inode_operations.
  The pointer to target kobject is saved in the link dentry's d_fsdata field.
  The target path is generated everytime we do ->readlink and ->follow_link.
  This results in generating the correct target path during readlink and
  follow_link operations inspite of renamed target kobject.

o This also pins the target kobject during link creation and the ref. is
  released when the link is removed.

o Apart from being correct this patch also saves some memory by not pinning
  a whole page for saving the target information.

o Used a rw_semaphor sysfs_rename_sem to avoid clashing with renaming of
  ancestors while the target path is generated.

o Used dcache_lock in fs/sysfs/sysfs.h:sysfs_get_kobject() because of using
  d_drop() while removing dentries.