Use invalidate_lock instead of XFS internal i_mmap_lock. The intended
purpose of invalidate_lock is exactly the same. Note that the locking in
__xfs_filemap_fault() slightly changes as filemap_fault() already takes
invalidate_lock.
Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> CC: <linux-xfs@vger.kernel.org> CC: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz>