Remove the address_space ->tree_lock and use the xa_lock newly added to
the radix_tree_root.  Rename the address_space ->page_tree to ->i_pages,
since we don't really care that it's a tree.

[willy@infradead.org: fix nds32, fs/dax.c]
  Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use spin_lock/unlock_irq instead of doing nothing. This fixes corruptions
of the vma_interval_tree causing the kernel to be stuck in an
infinite loop in vma_interval_tree_foreach.

Signed-off-by: Julien Beraud <julien.beraud@spectracom.orolia.com>
Acked-by: Ley Foon Tan <ley.foon.tan@intel.com>

This patch adds functionality required for cache maintenance.

Signed-off-by: Ley Foon Tan <lftan@altera.com>