dax: Convert dax_layout_busy_page to XArray (084a8990) · Commits · 戴 / test

fs/dax.c

+21 −43

Original line number	Diff line number	Diff line
		@@ -722,11 +722,10 @@ restart:
		*/
		struct page dax_layout_busy_page(struct address_space mapping)
		{
		pgoff_t indices[PAGEVEC_SIZE];
		XA_STATE(xas, &mapping->i_pages, 0);
		void *entry;
		unsigned int scanned = 0;
		struct page *page = NULL;
		struct pagevec pvec;
		pgoff_t index, end;
		unsigned i;

		/*
		* In the 'limited' case get_user_pages() for dax is disabled.
		@@ -737,13 +736,9 @@ struct page dax_layout_busy_page(struct address_space mapping)
		if (!dax_mapping(mapping) \|\| !mapping_mapped(mapping))
		return NULL;

		pagevec_init(&pvec);
		index = 0;
		end = -1;

		/*
		* If we race get_user_pages_fast() here either we'll see the
		* elevated page count in the pagevec_lookup and wait, or
		* elevated page count in the iteration and wait, or
		* get_user_pages_fast() will see that the page it took a reference
		* against is no longer mapped in the page tables and bail to the
		* get_user_pages() slow path. The slow path is protected by
		@@ -755,43 +750,26 @@ struct page dax_layout_busy_page(struct address_space mapping)
		*/
		unmap_mapping_range(mapping, 0, 0, 1);

		while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
		min(end - index, (pgoff_t)PAGEVEC_SIZE),
		indices)) {
		for (i = 0; i < pagevec_count(&pvec); i++) {
		struct page *pvec_ent = pvec.pages[i];
		void *entry;

		index = indices[i];
		if (index >= end)
		break;

		if (WARN_ON_ONCE(!xa_is_value(pvec_ent)))
		xas_lock_irq(&xas);
		xas_for_each(&xas, entry, ULONG_MAX) {
		if (WARN_ON_ONCE(!xa_is_value(entry)))
		continue;

		xa_lock_irq(&mapping->i_pages);
		entry = get_unlocked_mapping_entry(mapping, index, NULL);
		if (unlikely(dax_is_locked(entry)))
		entry = get_unlocked_entry(&xas);
		if (entry)
		page = dax_busy_page(entry);
		put_unlocked_mapping_entry(mapping, index, entry);
		xa_unlock_irq(&mapping->i_pages);
		put_unlocked_entry(&xas, entry);
		if (page)
		break;
		}

		/*
		* We don't expect normal struct page entries to exist in our
		* tree, but we keep these pagevec calls so that this code is
		* consistent with the common pattern for handling pagevecs
		* throughout the kernel.
		*/
		pagevec_remove_exceptionals(&pvec);
		pagevec_release(&pvec);
		index++;
		if (++scanned % XA_CHECK_SCHED)
		continue;

		if (page)
		break;
		xas_pause(&xas);
		xas_unlock_irq(&xas);
		cond_resched();
		xas_lock_irq(&xas);
		}
		xas_unlock_irq(&xas);
		return page;
		}
		EXPORT_SYMBOL_GPL(dax_layout_busy_page);

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