From patchwork Wed Dec 6 00:41:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 10094465 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B2D8060329 for ; Wed, 6 Dec 2017 00:53:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A201028573 for ; Wed, 6 Dec 2017 00:53:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 96CD128A27; Wed, 6 Dec 2017 00:53:41 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4841028573 for ; Wed, 6 Dec 2017 00:53:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754039AbdLFAxi (ORCPT ); Tue, 5 Dec 2017 19:53:38 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:50790 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753346AbdLFAmN (ORCPT ); Tue, 5 Dec 2017 19:42:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9dfa5xjfob0XhxbetJUhn15cyMrS/GsRs7cI8PzMX9c=; b=FeX2D55oMpftaZIZQw6jpJ+CT GINziyh4fvKc2NIOZCJOhKn2MsH5f+IY+keaTQmejHPXpOKQXEY9N8yCzvUo0JFCeMmX/11tfJjer P+VYr9vWqxDwB2bdCAqTtGzQuOyShhk4Yz61TIpRG0Mw4dM3VfiD7ST8XCRYaSB19muD7S+zG6r13 w6nKMhDsiv3si0l9hVm9XI5D5Qc4jbHeyJ2oZAZ0erKFFoU/nqdDCExxtRXlkI7G8TjlYmJm3s+Lx CqB6sLxUTJeT2a8+unbE8aivSEo7+J5M6B+FAYc6QbqDn6Uqyh/3uAU6U2QeGeTXvtZz89/tv16iW 9Pa75sGgQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.87 #1 (Red Hat Linux)) id 1eMNms-00017j-TE; Wed, 06 Dec 2017 00:42:10 +0000 From: Matthew Wilcox Cc: Matthew Wilcox , Ross Zwisler , Jens Axboe , Rehas Sachdeva , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 44/73] shmem: Convert shmem_tag_pins to XArray Date: Tue, 5 Dec 2017 16:41:30 -0800 Message-Id: <20171206004159.3755-45-willy@infradead.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171206004159.3755-1-willy@infradead.org> References: <20171206004159.3755-1-willy@infradead.org> To: unlisted-recipients:; (no To-header on input) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Matthew Wilcox Simplify the locking by taking the spinlock while we walk the tree on the assumption that many acquires and releases of the lock will be worse than holding the lock for a (potentially) long time. We could replicate the same locking behaviour with the xarray, but would have to be careful that the xa_node wasn't RCU-freed under us before we took the lock. Signed-off-by: Matthew Wilcox --- mm/shmem.c | 39 ++++++++++++++++----------------------- 1 file changed, 16 insertions(+), 23 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index ce285ae635ea..2f41c7ceea18 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2601,35 +2601,28 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) static void shmem_tag_pins(struct address_space *mapping) { - struct radix_tree_iter iter; - void **slot; - pgoff_t start; + XA_STATE(xas, &mapping->pages, 0); struct page *page; + unsigned int tagged = 0; lru_add_drain(); - start = 0; - rcu_read_lock(); - radix_tree_for_each_slot(slot, &mapping->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); - continue; - } - } else if (page_count(page) - page_mapcount(page) > 1) { - xa_lock_irq(&mapping->pages); - radix_tree_tag_set(&mapping->pages, iter.index, - SHMEM_TAG_PINNED); - xa_unlock_irq(&mapping->pages); - } + xas_lock_irq(&xas); + xas_for_each(&xas, page, ULONG_MAX) { + if (xa_is_value(page)) + continue; + if (page_count(page) - page_mapcount(page) > 1) + xas_set_tag(&xas, SHMEM_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); } /*