page cache: use xa_lock

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>

1 files changed, 5 insertions, 4 deletions

diff --git a/fs/afs/write.c b/fs/afs/write.c
index 9370e2feb999..dbc3c0b0142d 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -570,10 +570,11 @@ static int afs_writepages_region(struct address_space *mapping,
 
                 _debug("wback %lx", page->index);
 
-                /* at this point we hold neither mapping->tree_lock nor lock on
-                 * the page itself: the page may be truncated or invalidated
-                 * (changing page->mapping to NULL), or even swizzled back from
-                 * swapper_space to tmpfs file mapping
+                /*
+                 * at this point we hold neither the i_pages lock nor the
+                 * page lock: the page may be truncated or invalidated
+                 * (changing page->mapping to NULL), or even swizzled
+                 * back from swapper_space to tmpfs file mapping
                  */
                 ret = lock_page_killable(page);
                 if (ret < 0) {