Commit ef3038a5 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

memfd: Convert memfd_tag_pins to XArray 



Switch to a batch-processing model like memfd_wait_for_pins() and
use the xa_state previously set up by memfd_wait_for_pins().

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
parent 2313216f

mm/memfd.c

+18 −26
Original line number Diff line number Diff line
@@ -28,37 +28,29 @@ 
#define MEMFD_TAG_PINNED        PAGECACHE_TAG_TOWRITE

#define LAST_SCAN               4       /* about 150ms max */



static void memfd_tag_pins(struct address_space *mapping)

static void memfd_tag_pins(struct xa_state *xas)

{

	struct radix_tree_iter iter;

	void __rcu **slot;

	pgoff_t start;

	struct page *page;

	unsigned int tagged = 0;



	lru_add_drain();

	start = 0;

	rcu_read_lock();



	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {

		page = radix_tree_deref_slot(slot);

		if (!page || radix_tree_exception(page)) {

			if (radix_tree_deref_retry(page)) {

				slot = radix_tree_iter_retry(&iter);



	xas_lock_irq(xas);

	xas_for_each(xas, page, ULONG_MAX) {

		if (xa_is_value(page))

			continue;

			}

		} else if (page_count(page) - page_mapcount(page) > 1) {

			xa_lock_irq(&mapping->i_pages);

			radix_tree_tag_set(&mapping->i_pages, iter.index,

					   MEMFD_TAG_PINNED);

			xa_unlock_irq(&mapping->i_pages);

		}

		if (page_count(page) - page_mapcount(page) > 1)

			xas_set_mark(xas, MEMFD_TAG_PINNED);



		if (need_resched()) {

			slot = radix_tree_iter_resume(slot, &iter);

			cond_resched_rcu();

		}

		if (++tagged % XA_CHECK_SCHED)

			continue;



		xas_pause(xas);

		xas_unlock_irq(xas);

		cond_resched();

		xas_lock_irq(xas);

	}

	rcu_read_unlock();

	xas_unlock_irq(xas);

}



/*
@@ -76,7 +68,7 @@ static int memfd_wait_for_pins(struct address_space *mapping) 
	struct page *page;

	int error, scan;



	memfd_tag_pins(mapping);

	memfd_tag_pins(&xas);



	error = 0;

	for (scan = 0; scan <= LAST_SCAN; scan++) {