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, 11 insertions, 11 deletions

diff --git a/mm/workingset.c b/mm/workingset.c
index b7d616a3bbbe..40ee02c83978 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -202,7 +202,7 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
  * @mapping: address space the page was backing
  * @page: the page being evicted
  *
- * Returns a shadow entry to be stored in @mapping->page_tree in place
+ * Returns a shadow entry to be stored in @mapping->i_pages in place
  * of the evicted @page so that a later refault can be detected.
  */
 void *workingset_eviction(struct address_space *mapping, struct page *page)
@@ -348,7 +348,7 @@ void workingset_update_node(struct radix_tree_node *node)
 	 *
 	 * Avoid acquiring the list_lru lock when the nodes are
 	 * already where they should be. The list_empty() test is safe
-	 * as node->private_list is protected by &mapping->tree_lock.
+	 * as node->private_list is protected by the i_pages lock.
 	 */
 	if (node->count && node->count == node->exceptional) {
 		if (list_empty(&node->private_list))
@@ -366,7 +366,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	unsigned long nodes;
 	unsigned long cache;
 
-	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
+	/* list_lru lock nests inside the IRQ-safe i_pages lock */
 	local_irq_disable();
 	nodes = list_lru_shrink_count(&shadow_nodes, sc);
 	local_irq_enable();
@@ -419,21 +419,21 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 
 	/*
 	 * Page cache insertions and deletions synchroneously maintain
-	 * the shadow node LRU under the mapping->tree_lock and the
+	 * the shadow node LRU under the i_pages lock and the
 	 * lru_lock.  Because the page cache tree is emptied before
 	 * the inode can be destroyed, holding the lru_lock pins any
 	 * address_space that has radix tree nodes on the LRU.
 	 *
-	 * We can then safely transition to the mapping->tree_lock to
+	 * We can then safely transition to the i_pages lock to
 	 * pin only the address_space of the particular node we want
 	 * to reclaim, take the node off-LRU, and drop the lru_lock.
 	 */
 
 	node = container_of(item, struct radix_tree_node, private_list);
-	mapping = container_of(node->root, struct address_space, page_tree);
+	mapping = container_of(node->root, struct address_space, i_pages);
 
 	/* Coming from the list, invert the lock order */
-	if (!spin_trylock(&mapping->tree_lock)) {
+	if (!xa_trylock(&mapping->i_pages)) {
 		spin_unlock(lru_lock);
 		ret = LRU_RETRY;
 		goto out;
@@ -468,11 +468,11 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	if (WARN_ON_ONCE(node->exceptional))
 		goto out_invalid;
 	inc_lruvec_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM);
-	__radix_tree_delete_node(&mapping->page_tree, node,
+	__radix_tree_delete_node(&mapping->i_pages, node,
 				 workingset_lookup_update(mapping));
 
 out_invalid:
-	spin_unlock(&mapping->tree_lock);
+	xa_unlock(&mapping->i_pages);
 	ret = LRU_REMOVED_RETRY;
 out:
 	local_irq_enable();
@@ -487,7 +487,7 @@ static unsigned long scan_shadow_nodes(struct shrinker *shrinker,
 {
 	unsigned long ret;
 
-	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
+	/* list_lru lock nests inside the IRQ-safe i_pages lock */
 	local_irq_disable();
 	ret = list_lru_shrink_walk(&shadow_nodes, sc, shadow_lru_isolate, NULL);
 	local_irq_enable();
@@ -503,7 +503,7 @@ static struct shrinker workingset_shadow_shrinker = {
 
 /*
  * Our list_lru->lock is IRQ-safe as it nests inside the IRQ-safe
- * mapping->tree_lock.
+ * i_pages lock.
  */
 static struct lock_class_key shadow_nodes_key;