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Commit 3ece58a2 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

page cache: Convert find_get_pages_contig to XArray 



There's no direct replacement for radix_tree_for_each_contig()
in the XArray API as it's an unusual thing to do.  Instead,
open-code a loop using xas_next().  This removes the only user of
radix_tree_for_each_contig() so delete the iterator from the API and
the test suite code for it.

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent fd1b3cee

.clang-format

+0 −1
Original line number Diff line number Diff line
@@ -323,7 +323,6 @@ ForEachMacros: 
  - 'protocol_for_each_card'

  - 'protocol_for_each_dev'

  - 'queue_for_each_hw_ctx'

  - 'radix_tree_for_each_contig'

  - 'radix_tree_for_each_slot'

  - 'radix_tree_for_each_tagged'

  - 'rbtree_postorder_for_each_entry_safe'

include/linux/radix-tree.h

+0 −17
Original line number Diff line number Diff line
@@ -522,23 +522,6 @@ static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot, 
	     slot || (slot = radix_tree_next_chunk(root, iter, 0)) ;	\

	     slot = radix_tree_next_slot(slot, iter, 0))



/**

 * radix_tree_for_each_contig - iterate over contiguous slots

 *

 * @slot:	the void** variable for pointer to slot

 * @root:	the struct radix_tree_root pointer

 * @iter:	the struct radix_tree_iter pointer

 * @start:	iteration starting index

 *

 * @slot points to radix tree slot, @iter->index contains its index.

 */

#define radix_tree_for_each_contig(slot, root, iter, start)		\

	for (slot = radix_tree_iter_init(iter, start) ;			\

	     slot || (slot = radix_tree_next_chunk(root, iter,		\

				RADIX_TREE_ITER_CONTIG)) ;		\

	     slot = radix_tree_next_slot(slot, iter,			\

				RADIX_TREE_ITER_CONTIG))



/**

 * radix_tree_for_each_tagged - iterate over tagged slots

 *

mm/filemap.c

+22 −31
Original line number Diff line number Diff line
@@ -1721,57 +1721,43 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start, 
unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,

			       unsigned int nr_pages, struct page **pages)

{

	struct radix_tree_iter iter;

	void **slot;

	XA_STATE(xas, &mapping->i_pages, index);

	struct page *page;

	unsigned int ret = 0;



	if (unlikely(!nr_pages))

		return 0;



	rcu_read_lock();

	radix_tree_for_each_contig(slot, &mapping->i_pages, &iter, index) {

		struct page *head, *page;

repeat:

		page = radix_tree_deref_slot(slot);

		/* The hole, there no reason to continue */

		if (unlikely(!page))

			break;



		if (radix_tree_exception(page)) {

			if (radix_tree_deref_retry(page)) {

				slot = radix_tree_iter_retry(&iter);

	for (page = xas_load(&xas); page; page = xas_next(&xas)) {

		struct page *head;

		if (xas_retry(&xas, page))

			continue;

			}

		/*

			 * A shadow entry of a recently evicted page,

			 * or a swap entry from shmem/tmpfs.  Stop

			 * looking for contiguous pages.

		 * If the entry has been swapped out, we can stop looking.

		 * No current caller is looking for DAX entries.

		 */

		if (xa_is_value(page))

			break;

		}



		head = compound_head(page);

		if (!page_cache_get_speculative(head))

			goto repeat;

			goto retry;



		/* The page was split under us? */

		if (compound_head(page) != head) {

			put_page(head);

			goto repeat;

		}

		if (compound_head(page) != head)

			goto put_page;



		/* Has the page moved? */

		if (unlikely(page != *slot)) {

			put_page(head);

			goto repeat;

		}

		if (unlikely(page != xas_reload(&xas)))

			goto put_page;



		/*

		 * must check mapping and index after taking the ref.

		 * otherwise we can get both false positives and false

		 * negatives, which is just confusing to the caller.

		 */

		if (page->mapping == NULL || page_to_pgoff(page) != iter.index) {

		if (!page->mapping || page_to_pgoff(page) != xas.xa_index) {

			put_page(page);

			break;

		}
@@ -1779,6 +1765,11 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, 
		pages[ret] = page;

		if (++ret == nr_pages)

			break;

		continue;

put_page:

		put_page(head);

retry:

		xas_reset(&xas);

	}

	rcu_read_unlock();

	return ret;

tools/testing/radix-tree/regression3.c

+0 −23
Original line number Diff line number Diff line
@@ -69,21 +69,6 @@ void regression3_test(void) 
			continue;

		}

	}

	radix_tree_delete(&root, 1);



	first = true;

	radix_tree_for_each_contig(slot, &root, &iter, 0) {

		printv(2, "contig %ld %p\n", iter.index, *slot);

		if (first) {

			radix_tree_insert(&root, 1, ptr);

			first = false;

		}

		if (radix_tree_deref_retry(*slot)) {

			printv(2, "retry at %ld\n", iter.index);

			slot = radix_tree_iter_retry(&iter);

			continue;

		}

	}



	radix_tree_for_each_slot(slot, &root, &iter, 0) {

		printv(2, "slot %ld %p\n", iter.index, *slot);
@@ -93,14 +78,6 @@ void regression3_test(void) 
		}

	}



	radix_tree_for_each_contig(slot, &root, &iter, 0) {

		printv(2, "contig %ld %p\n", iter.index, *slot);

		if (!iter.index) {

			printv(2, "next at %ld\n", iter.index);

			slot = radix_tree_iter_resume(slot, &iter);

		}

	}



	radix_tree_tag_set(&root, 0, 0);

	radix_tree_tag_set(&root, 1, 0);

	radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) {