[XFS] remove manual lookup from xfs_rename and simplify locking

->rename already gets the target inode passed if it exits. Pass it down to
xfs_rename so that we can avoid looking it up again. Also simplify locking
as the first lock section in xfs_rename can go away now: the isdir is an
invariant over the lifetime of the inode, and new_parent and the nlink
check are namespace topology protected by i_mutex in the VFS. The projid
check needs to move into the second lock section anyway to not be racy.

Also kill the now unused xfs_dir_lookup_int and remove the now-unused
first_locked argumet to xfs_lock_inodes.

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30903a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

fs/xfs/linux-2.6/xfs_iops.c

@@ -511,7 +511,8 @@ xfs_vn_rename(
 	xfs_dentry_to_name(&nname, ndentry);
 
 	error = xfs_rename(XFS_I(odir), &oname, XFS_I(odentry->d_inode),
-							XFS_I(ndir), &nname);
+			   XFS_I(ndir), &nname, new_inode ?
+			   			XFS_I(new_inode) : NULL);
 	if (likely(!error)) {
 		if (new_inode)
 			xfs_validate_fields(new_inode);