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, 4 insertions, 4 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2aa02cad94d4..92efaf1f8977 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -13,6 +13,7 @@
 #include <linux/list_lru.h>
 #include <linux/llist.h>
 #include <linux/radix-tree.h>
+#include <linux/xarray.h>
 #include <linux/rbtree.h>
 #include <linux/init.h>
 #include <linux/pid.h>
@@ -390,12 +391,11 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
 
 struct address_space {
         struct inode            *host;          /* owner: inode, block_device */
-        struct radix_tree_root  page_tree;      /* radix tree of all pages */
-        spinlock_t              tree_lock;      /* and lock protecting it */
+        struct radix_tree_root  i_pages;        /* cached pages */
         atomic_t                i_mmap_writable;/* count VM_SHARED mappings */
         struct rb_root_cached   i_mmap;         /* tree of private and shared mappings */
         struct rw_semaphore     i_mmap_rwsem;   /* protect tree, count, list */
-        /* Protected by tree_lock together with the radix tree */
+        /* Protected by the i_pages lock */
         unsigned long           nrpages;        /* number of total pages */
         /* number of shadow or DAX exceptional entries */
         unsigned long           nrexceptional;
@@ -1989,7 +1989,7 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
  *
  * I_WB_SWITCH          Cgroup bdi_writeback switching in progress.  Used to
  *                      synchronize competing switching instances and to tell
- *                      wb stat updates to grab mapping->tree_lock.  See
+ *                      wb stat updates to grab the i_pages lock.  See
  *                      inode_switch_wb_work_fn() for details.
  *
  * I_OVL_INUSE          Used by overlayfs to get exclusive ownership on upper