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, 8 insertions, 9 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index f233dccd3b1b..07f9aa2340c3 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -124,10 +124,10 @@ int __add_to_swap_cache(struct page *page, swp_entry_t entry)
         SetPageSwapCache(page);
 
         address_space = swap_address_space(entry);
-        spin_lock_irq(&address_space->tree_lock);
+        xa_lock_irq(&address_space->i_pages);
         for (i = 0; i < nr; i++) {
                 set_page_private(page + i, entry.val + i);
-                error = radix_tree_insert(&address_space->page_tree,
+                error = radix_tree_insert(&address_space->i_pages,
                                           idx + i, page + i);
                 if (unlikely(error))
                         break;
@@ -145,13 +145,13 @@ int __add_to_swap_cache(struct page *page, swp_entry_t entry)
                 VM_BUG_ON(error == -EEXIST);
                 set_page_private(page + i, 0UL);
                 while (i--) {
-                        radix_tree_delete(&address_space->page_tree, idx + i);
+                        radix_tree_delete(&address_space->i_pages, idx + i);
                         set_page_private(page + i, 0UL);
                 }
                 ClearPageSwapCache(page);
                 page_ref_sub(page, nr);
         }
-        spin_unlock_irq(&address_space->tree_lock);
+        xa_unlock_irq(&address_space->i_pages);
 
         return error;
 }
@@ -188,7 +188,7 @@ void __delete_from_swap_cache(struct page *page)
         address_space = swap_address_space(entry);
         idx = swp_offset(entry);
         for (i = 0; i < nr; i++) {
-                radix_tree_delete(&address_space->page_tree, idx + i);
+                radix_tree_delete(&address_space->i_pages, idx + i);
                 set_page_private(page + i, 0);
         }
         ClearPageSwapCache(page);
@@ -272,9 +272,9 @@ void delete_from_swap_cache(struct page *page)
         entry.val = page_private(page);
 
         address_space = swap_address_space(entry);
-        spin_lock_irq(&address_space->tree_lock);
+        xa_lock_irq(&address_space->i_pages);
         __delete_from_swap_cache(page);
-        spin_unlock_irq(&address_space->tree_lock);
+        xa_unlock_irq(&address_space->i_pages);
 
         put_swap_page(page, entry);
         page_ref_sub(page, hpage_nr_pages(page));
@@ -628,12 +628,11 @@ int init_swap_address_space(unsigned int type, unsigned long nr_pages)
                 return -ENOMEM;
         for (i = 0; i < nr; i++) {
                 space = spaces + i;
-                INIT_RADIX_TREE(&space->page_tree, GFP_ATOMIC|__GFP_NOWARN);
+                INIT_RADIX_TREE(&space->i_pages, GFP_ATOMIC|__GFP_NOWARN);
                 atomic_set(&space->i_mmap_writable, 0);
                 space->a_ops = &swap_aops;
                 /* swap cache doesn't use writeback related tags */
                 mapping_set_no_writeback_tags(space);
-                spin_lock_init(&space->tree_lock);
         }
         nr_swapper_spaces[type] = nr;
         rcu_assign_pointer(swapper_spaces[type], spaces);