From patchwork Mon Oct 26 18:31:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11858199 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BF0C192C for ; Mon, 26 Oct 2020 18:31:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B8202231B for ; Mon, 26 Oct 2020 18:31:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="AvQOhwnb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1789832AbgJZSbo (ORCPT ); Mon, 26 Oct 2020 14:31:44 -0400 Received: from casper.infradead.org ([90.155.50.34]:47260 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1789824AbgJZSbn (ORCPT ); Mon, 26 Oct 2020 14:31:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=Nxr3mPTUTpTqNHQZgTOz1Cs76dGKRGwiKCi73s14jS4=; b=AvQOhwnb29KFpHetuF8xRT99VV i8gl5AB+jf/uhEqufUz88wxjT/paeS3Rh1DaYQ9NbhHEN+5ZFXil+zW0/etcNn5VlB3/gXu3w9gv5 PJfCafIsc2b7mqgQAl4g79A+WThihEMzUiceLq3ejap/cq/xJ+sUlWzx2um7dJfp12yIOodh7sdYV j4CrWK15YfOYhy0gk92KD//1A16vxbBk04zZPVZGgCYaS85dj5OPTzGt6Lwy8Jse+bYYYEDGUrmj+ jO1TD9NSXQBtno+1QwKSgRkRtrEZqMogO+18xAHjt1uZ0cdvUNZhdXLTftkC5VruphqUw3L6Ki/8c na6JiiGQ==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kX7HS-0002jU-94; Mon, 26 Oct 2020 18:31:42 +0000 From: "Matthew Wilcox (Oracle)" To: linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org Subject: [PATCH 3/9] mm: Return head pages from grab_cache_page_write_begin Date: Mon, 26 Oct 2020 18:31:30 +0000 Message-Id: <20201026183136.10404-4-willy@infradead.org> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20201026183136.10404-1-willy@infradead.org> References: <20201026183136.10404-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This function is only called from filesystems on their own mapping, so no caller will be surprised by getting back a head page when they were expecting a tail page. This lets us remove a call to thp_head() in wait_for_stable_page(). Signed-off-by: Matthew Wilcox (Oracle) --- mm/filemap.c | 12 ++++++++++-- mm/page-writeback.c | 2 +- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 2214a2c48dd1..62bc6affeb70 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3327,15 +3327,23 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) } EXPORT_SYMBOL(generic_file_direct_write); -/* +/** + * grab_cache_page_write_begin - Find or create a page for buffered writes. + * @mapping: The address space we're writing to. + * @index: The index we're writing to. + * @flags: %AOP_FLAG_NOFS to prevent memory reclaim calling the filesystem. + * * Find or create a page at the given pagecache position. Return the locked * page. This function is specifically for buffered writes. + * + * Return: The head page found in the cache, or NULL if no page could be + * created (due to lack of memory). */ struct page *grab_cache_page_write_begin(struct address_space *mapping, pgoff_t index, unsigned flags) { struct page *page; - int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT; + int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT|FGP_HEAD; if (flags & AOP_FLAG_NOFS) fgp_flags |= FGP_NOFS; diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 7709f0e223f5..3671568d433f 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2849,7 +2849,7 @@ EXPORT_SYMBOL_GPL(wait_on_page_writeback); */ void wait_for_stable_page(struct page *page) { - page = thp_head(page); + VM_BUG_ON_PGFLAGS(PageTail(page), page); if (page->mapping->host->i_sb->s_iflags & SB_I_STABLE_WRITES) wait_on_page_writeback(page); }