[PATCH v13 65/72] dax: Convert __dax_invalidate_entry to XArray

[Matthew Wilcox]

From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>

Avoids walking the radix tree multiple times looking for tags.

Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
 fs/dax.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index b8ed7bf32ba1..0566a150c458 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -676,27 +676,28 @@ EXPORT_SYMBOL_GPL(dax_layout_busy_page);
 static int __dax_invalidate_entry(struct address_space *mapping,
 					  pgoff_t index, bool trunc)
 {
+	XA_STATE(xas, &mapping->i_pages, index);
 	int ret = 0;
 	void *entry;
-	struct radix_tree_root *pages = &mapping->i_pages;
 
-	xa_lock_irq(pages);
-	entry = get_unlocked_mapping_entry(mapping, index, NULL);
+	xas_lock_irq(&xas);
+	entry = get_unlocked_entry(&xas);
 	if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
 		goto out;
 	if (!trunc &&
-	    (radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) ||
-	     radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE)))
+	    (xas_get_tag(&xas, PAGECACHE_TAG_DIRTY) ||
+	     xas_get_tag(&xas, PAGECACHE_TAG_TOWRITE)))
 		goto out;
 	dax_disassociate_entry(entry, mapping, trunc);
-	radix_tree_delete(pages, index);
+	xas_store(&xas, NULL);
 	mapping->nrexceptional--;
 	ret = 1;
 out:
-	put_unlocked_mapping_entry(mapping, index, entry);
-	xa_unlock_irq(pages);
+	put_unlocked_entry(&xas, entry);
+	xas_unlock_irq(&xas);
 	return ret;
 }
+
 /*
  * Delete DAX entry at @index from @mapping.  Wait for it
  * to be unlocked before deleting it.
-- 
2.17.1