From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40A2DC433E1 for ; Tue, 25 Aug 2020 05:48:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CFE22071E for ; Tue, 25 Aug 2020 05:48:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728882AbgHYFs0 (ORCPT ); Tue, 25 Aug 2020 01:48:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:50540 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728145AbgHYFs0 (ORCPT ); Tue, 25 Aug 2020 01:48:26 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B42BFACCF for ; Tue, 25 Aug 2020 05:48:55 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v3 1/4] btrfs: refactor @nrptrs calculation of btrfs_buffered_write() Date: Tue, 25 Aug 2020 13:48:05 +0800 Message-Id: <20200825054808.16241-2-wqu@suse.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200825054808.16241-1-wqu@suse.com> References: <20200825054808.16241-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org @nrptrs of btrfs_bufferd_write() determines the up limit of pages we can process in one batch. Refactor that calculation into its own function, and fix a small page alignment bug where the result can be one page less than ideal. Despite that, no functionality change. Signed-off-by: Qu Wenruo --- fs/btrfs/file.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 5a818ebcb01f..64f744989697 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1620,6 +1620,25 @@ void btrfs_check_nocow_unlock(struct btrfs_inode *inode) btrfs_drew_write_unlock(&inode->root->snapshot_lock); } +/* Helper to get how many pages we should alloc for the batch */ +static int calc_nr_pages(loff_t pos, struct iov_iter *iov) +{ + int nr_pages; + + /* + * Try to cover the full iov range, as btrfs metadata/data reserve + * and release can be pretty slow, thus the more pages we process in + * one batch the better. + */ + nr_pages = (round_up(pos + iov_iter_count(iov), PAGE_SIZE) - + round_down(pos, PAGE_SIZE)) / PAGE_SIZE; + + nr_pages = min(nr_pages, current->nr_dirtied_pause - + current->nr_dirtied); + nr_pages = max(nr_pages, 8); + return nr_pages; +} + static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) { @@ -1638,10 +1657,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, bool only_release_metadata = false; bool force_page_uptodate = false; - nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE), - PAGE_SIZE / (sizeof(struct page *))); - nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied); - nrptrs = max(nrptrs, 8); + nrptrs = calc_nr_pages(pos, i); pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL); if (!pages) return -ENOMEM; -- 2.28.0