From patchwork Thu Jan 21 04:16:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 12034471 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 C80C5C433DB for ; Thu, 21 Jan 2021 04:27:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F5F32389A for ; Thu, 21 Jan 2021 04:27:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727706AbhAUE1j (ORCPT ); Wed, 20 Jan 2021 23:27:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726917AbhAUE1H (ORCPT ); Wed, 20 Jan 2021 23:27:07 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAC19C0613C1 for ; Wed, 20 Jan 2021 20:26:16 -0800 (PST) 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=cCpO00SFBp0/M+OPnIkbSN6EvBTGTW5uWRa8yrKkcTs=; b=iUPbv9td/FCePLLiZuPCft2DGq 60UVsB0tdgI9dSxev627/lsFBgTe2Dp5Z5ONKxZ7Is4Oih0jOm3IaI7Ea31Xx9NUphIebSe62uN4p TZiz1jdIIKfZ/+Nx4cVEGBK6YiGF06KXrDnzugyh6hD2Dk8CAGGKIXfCWZmu0kMUXRzLwx+jzSMEv 1BaQW03ZY+O9toiLnPgxbsWJxkYlsAitc0lLj9ikjfLKLaIiCip9P9smwGC0XbGw+yJrhtZwX+n9D ggO4A+En/5JVQwBS0Cbp2pJzrDw2IN9RRHrkc2x1e7zMM6p1/hy0a2G2KQWWCHs4vq+yEuOMWadPT 99tVU2Kw==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l2RWF-00GbW0-5D; Thu, 21 Jan 2021 04:25:09 +0000 From: "Matthew Wilcox (Oracle)" To: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , hch@lst.de, kent.overstreet@gmail.com Subject: [PATCH v4 11/18] mm/filemap: Convert filemap_update_page to return an errno Date: Thu, 21 Jan 2021 04:16:09 +0000 Message-Id: <20210121041616.3955703-12-willy@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210121041616.3955703-1-willy@infradead.org> References: <20210121041616.3955703-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Use AOP_TRUNCATED_PAGE to indicate that no error occurred, but the page we looked up is no longer valid. In this case, the reference to the page will have been removed; if we hit any other error, the caller will release the reference. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Kent Overstreet Reviewed-by: Christoph Hellwig --- mm/filemap.c | 38 +++++++++++++++++--------------------- 1 file changed, 17 insertions(+), 21 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 602191fe6c53f..adac12ed48415 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2223,24 +2223,21 @@ static int filemap_read_page(struct file *file, struct address_space *mapping, return error; } -static struct page *filemap_update_page(struct kiocb *iocb, struct file *filp, - struct iov_iter *iter, struct page *page, loff_t pos, - loff_t count) +static int filemap_update_page(struct kiocb *iocb, + struct address_space *mapping, struct iov_iter *iter, + struct page *page, loff_t pos, loff_t count) { - struct address_space *mapping = filp->f_mapping; struct inode *inode = mapping->host; int error; if (iocb->ki_flags & IOCB_WAITQ) { error = lock_page_async(page, iocb->ki_waitq); - if (error) { - put_page(page); - return ERR_PTR(error); - } + if (error) + return error; } else { if (!trylock_page(page)) { put_and_wait_on_page_locked(page, TASK_KILLABLE); - return NULL; + return AOP_TRUNCATED_PAGE; } } @@ -2259,25 +2256,21 @@ static struct page *filemap_update_page(struct kiocb *iocb, struct file *filp, goto readpage; uptodate: unlock_page(page); - return page; + return 0; readpage: if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) { unlock_page(page); - put_page(page); - return ERR_PTR(-EAGAIN); + return -EAGAIN; } error = filemap_read_page(iocb->ki_filp, mapping, page); - if (!error) - return page; - put_page(page); if (error == AOP_TRUNCATED_PAGE) - return NULL; - return ERR_PTR(error); + put_page(page); + return error; truncated: unlock_page(page); put_page(page); - return NULL; + return AOP_TRUNCATED_PAGE; } static int filemap_create_page(struct file *file, @@ -2371,11 +2364,12 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, goto err; } - page = filemap_update_page(iocb, filp, iter, page, + err = filemap_update_page(iocb, mapping, iter, page, pg_pos, pg_count); - if (IS_ERR_OR_NULL(page)) { + if (err) { + if (err < 0) + put_page(page); pvec->nr--; - err = PTR_ERR_OR_ZERO(page); } } } @@ -2383,6 +2377,8 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, err: if (likely(pvec->nr)) return 0; + if (err == AOP_TRUNCATED_PAGE) + goto find_page; if (err) return err; /*