Ejemplo n.º 1
0
/*
 * decide whether a page can be released, possibly by cancelling a store to it
 * - we're allowed to sleep if __GFP_DIRECT_RECLAIM is flagged
 */
bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
				  struct page *page,
				  gfp_t gfp)
{
	struct page *xpage;
	void *val;

	_enter("%p,%p,%x", cookie, page, gfp);

try_again:
	rcu_read_lock();
	val = radix_tree_lookup(&cookie->stores, page->index);
	if (!val) {
		rcu_read_unlock();
		fscache_stat(&fscache_n_store_vmscan_not_storing);
		__fscache_uncache_page(cookie, page);
		return true;
	}

	/* see if the page is actually undergoing storage - if so we can't get
	 * rid of it till the cache has finished with it */
	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		rcu_read_unlock();
		goto page_busy;
	}

	/* the page is pending storage, so we attempt to cancel the store and
	 * discard the store request so that the page can be reclaimed */
	spin_lock(&cookie->stores_lock);
	rcu_read_unlock();

	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		/* the page started to undergo storage whilst we were looking,
		 * so now we can only wait or return */
		spin_unlock(&cookie->stores_lock);
		goto page_busy;
	}

	xpage = radix_tree_delete(&cookie->stores, page->index);
	spin_unlock(&cookie->stores_lock);

	if (xpage) {
		fscache_stat(&fscache_n_store_vmscan_cancelled);
		fscache_stat(&fscache_n_store_radix_deletes);
		ASSERTCMP(xpage, ==, page);
	} else {
Ejemplo n.º 2
0
bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
				  struct page *page,
				  gfp_t gfp)
{
	struct page *xpage;
	void *val;

	_enter("%p,%p,%x", cookie, page, gfp);

	rcu_read_lock();
	val = radix_tree_lookup(&cookie->stores, page->index);
	if (!val) {
		rcu_read_unlock();
		fscache_stat(&fscache_n_store_vmscan_not_storing);
		__fscache_uncache_page(cookie, page);
		return true;
	}

	/*                                                                    
                                                  */
	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		rcu_read_unlock();
		goto page_busy;
	}

	/*                                                                   
                                                                */
	spin_lock(&cookie->stores_lock);
	rcu_read_unlock();

	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		/*                                                            
                                       */
		spin_unlock(&cookie->stores_lock);
		goto page_busy;
	}

	xpage = radix_tree_delete(&cookie->stores, page->index);
	spin_unlock(&cookie->stores_lock);

	if (xpage) {
		fscache_stat(&fscache_n_store_vmscan_cancelled);
		fscache_stat(&fscache_n_store_radix_deletes);
		ASSERTCMP(xpage, ==, page);
	} else {