Embed a struct path into struct nameidata instead of nd->{dentry,mnt}

This is the central patch of a cleanup series. In most cases there is no good
reason why someone would want to use a dentry for itself. This series reflects
that fact and embeds a struct path into nameidata.

Together with the other patches of this series
- it enforced the correct order of getting/releasing the reference count on
  <dentry,vfsmount> pairs
- it prepares the VFS for stacking support since it is essential to have a
  struct path in every place where the stack can be traversed
- it reduces the overall code size:

without patch series:
   text    data     bss     dec     hex filename
5321639  858418  715768 6895825  6938d1 vmlinux

with patch series:
   text    data     bss     dec     hex filename
5320026  858418  715768 6894212  693284 vmlinux

This patch:

Switch from nd->{dentry,mnt} to nd->path.{dentry,mnt} everywhere.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix cifs]
[akpm@linux-foundation.org: fix smack]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 6033f0c..2d1d6ac 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -2026,12 +2026,12 @@
 	if (err)
 		return err;
 	/* Quotafile not on the same filesystem? */
-	if (nd.mnt->mnt_sb != sb) {
+	if (nd.path.mnt->mnt_sb != sb) {
 		path_release(&nd);
 		return -EXDEV;
 	}
 	/* We must not pack tails for quota files on reiserfs for quota IO to work */
-	if (!REISERFS_I(nd.dentry->d_inode)->i_flags & i_nopack_mask) {
+	if (!REISERFS_I(nd.path.dentry->d_inode)->i_flags & i_nopack_mask) {
 		reiserfs_warning(sb,
 				 "reiserfs: Quota file must have tail packing disabled.");
 		path_release(&nd);
@@ -2044,7 +2044,7 @@
 		return vfs_quota_on(sb, type, format_id, path);
 	}
 	/* Quotafile not of fs root? */
-	if (nd.dentry->d_parent->d_inode != sb->s_root->d_inode)
+	if (nd.path.dentry->d_parent->d_inode != sb->s_root->d_inode)
 		reiserfs_warning(sb,
 				 "reiserfs: Quota file not on filesystem root. "
 				 "Journalled quota will not work.");