[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/xfs_utils.h

@@ -21,8 +21,6 @@
 #define IRELE(ip)	VN_RELE(XFS_ITOV(ip))
 #define IHOLD(ip)	VN_HOLD(XFS_ITOV(ip))
 
-extern int xfs_dir_lookup_int(xfs_inode_t *, uint, struct xfs_name *,
-				xfs_ino_t *, xfs_inode_t **);
 extern int xfs_truncate_file(xfs_mount_t *, xfs_inode_t *);
 extern int xfs_dir_ialloc(xfs_trans_t **, xfs_inode_t *, mode_t, xfs_nlink_t,
 				xfs_dev_t, cred_t *, prid_t, int,