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=-11.2 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_SANE_1 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 6765DC2D0A3 for ; Fri, 6 Nov 2020 08:14:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1EA6208B3 for ; Fri, 6 Nov 2020 08:14:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726190AbgKFIOY (ORCPT ); Fri, 6 Nov 2020 03:14:24 -0500 Received: from verein.lst.de ([213.95.11.211]:50564 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726027AbgKFIOY (ORCPT ); Fri, 6 Nov 2020 03:14:24 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 46A1D68B05; Fri, 6 Nov 2020 09:14:21 +0100 (CET) Date: Fri, 6 Nov 2020 09:14:20 +0100 From: Christoph Hellwig To: "Matthew Wilcox (Oracle)" Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, hch@lst.de, kent.overstreet@gmail.com Subject: Re: [PATCH v2 11/18] mm/filemap: Convert filemap_update_page to return an errno Message-ID: <20201106081420.GF31585@lst.de> References: <20201104204219.23810-1-willy@infradead.org> <20201104204219.23810-12-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201104204219.23810-12-willy@infradead.org> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Nov 04, 2020 at 08:42:12PM +0000, Matthew Wilcox (Oracle) wrote: > Use AOP_TRUNCATED_PAGE to indicate that no error occurred, but the > page we looked up is no longer valid. > > Signed-off-by: Matthew Wilcox (Oracle) > Reviewed-by: Kent Overstreet > --- > mm/filemap.c | 42 +++++++++++++++++++----------------------- > 1 file changed, 19 insertions(+), 23 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 25945fefdd39..93c054f51677 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2231,24 +2231,21 @@ static int filemap_read_page(struct file *file, struct address_space *mapping, > return error; > } > > +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 inode *inode = mapping->host; > int error; > > if (iocb->ki_flags & IOCB_WAITQ) { > error = lock_page_async(page, iocb->ki_waitq); > + if (error) > + goto error; > } else { > if (!trylock_page(page)) { > put_and_wait_on_page_locked(page, TASK_KILLABLE); > + return AOP_TRUNCATED_PAGE; > } > } > > @@ -2267,25 +2264,24 @@ static struct page *filemap_update_page(struct kiocb *iocb, struct file *filp, > goto readpage; > uptodate: > unlock_page(page); > + return 0; > > readpage: > if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) { > unlock_page(page); > + error = -EAGAIN; > + } else { > + error = filemap_read_page(iocb->ki_filp, mapping, page); > + if (!error) > + return 0; > } > +error: > put_page(page); > + return error; > truncated: > unlock_page(page); > put_page(page); > + return AOP_TRUNCATED_PAGE; We could still consolidate the page unlocking by having another label. Or even better move the put_page into the caller like I did in my series, which would conceputally fit in pretty nicely here: > + err = filemap_update_page(iocb, mapping, iter, page, > pg_pos, pg_count); > + if (err) > pvec->nr--; But otherwise this looks good: Reviewed-by: Christoph Hellwig