btrfs: Convert page cache to XArray

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: David Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -437,9 +437,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
 		if (pg_index > end_index)
 			break;
 
-		rcu_read_lock();
-		page = radix_tree_lookup(&mapping->i_pages, pg_index);
-		rcu_read_unlock();
+		page = xa_load(&mapping->i_pages, pg_index);
 		if (page && !xa_is_value(page)) {
 			misses++;
 			if (misses > 4)

fs/btrfs/extent_io.c

@@ -5153,11 +5153,9 @@ void clear_extent_buffer_dirty(struct extent_buffer *eb)
 
 		clear_page_dirty_for_io(page);
 		xa_lock_irq(&page->mapping->i_pages);
-		if (!PageDirty(page)) {
-			radix_tree_tag_clear(&page->mapping->i_pages,
-						page_index(page),
-						PAGECACHE_TAG_DIRTY);
-		}
+		if (!PageDirty(page))
+			__xa_clear_mark(&page->mapping->i_pages,
+					page_index(page), PAGECACHE_TAG_DIRTY);
 		xa_unlock_irq(&page->mapping->i_pages);
 		ClearPageError(page);
 		unlock_page(page);