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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 7C84DC636C8 for ; Thu, 15 Jul 2021 20:59:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67E9F613DB for ; Thu, 15 Jul 2021 20:59:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230039AbhGOVCQ (ORCPT ); Thu, 15 Jul 2021 17:02:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:35534 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229459AbhGOVCM (ORCPT ); Thu, 15 Jul 2021 17:02:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3DCC5613DB; Thu, 15 Jul 2021 20:59:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626382758; bh=0EucBWjY29MULPwrccvkBApnBg2v72BlT6IHmjKghlU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=joTNieRPj8cS/TGFOPAPhkb0rc9ZVr8napBQt9m85+2DQVUkowqVmvDOze7153qj1 HwrO7MKTkSZYRtu0Fh8IcYTzQTlu8KHQ+da6BxpBW42CojKDcIF8bIXo9BYmlYYDJU AdILwiATZR4GYeTsCuEjyn7slVojO/WznHrA/HAxvEeDfdwodC0ywidsZP93BlE/pz owf/ZdXd4Y+8dQglmE/CefBkqmy/SBsrTBWaVcMwzwzbL3qsSklLSfdNeaY/T0Xn8f lsiiImBzEYzHe+E/wGlkAlm6oO5Ui2DT0iBCvJLS3BgHZWiQMSSWYIsCOnXr+w6CJX aoDJRiBBG53Vg== Date: Thu, 15 Jul 2021 13:59:17 -0700 From: "Darrick J. Wong" To: "Matthew Wilcox (Oracle)" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v14 090/138] block: Add bio_add_folio() Message-ID: <20210715205917.GC22357@magnolia> References: <20210715033704.692967-1-willy@infradead.org> <20210715033704.692967-91-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210715033704.692967-91-willy@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 15, 2021 at 04:36:16AM +0100, Matthew Wilcox (Oracle) wrote: > This is a thin wrapper around bio_add_page(). The main advantage here > is the documentation that the submitter can expect to see folios in the > completion handler, and that stupidly large folios are not supported. > It's not currently possible to allocate stupidly large folios, but if > it ever becomes possible, this function will fail gracefully instead of > doing I/O to the wrong bytes. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > block/bio.c | 21 +++++++++++++++++++++ > include/linux/bio.h | 3 ++- > 2 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/block/bio.c b/block/bio.c > index 1fab762e079b..1b500611d25c 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -933,6 +933,27 @@ int bio_add_page(struct bio *bio, struct page *page, > } > EXPORT_SYMBOL(bio_add_page); > > +/** > + * bio_add_folio - Attempt to add part of a folio to a bio. > + * @bio: Bio to add to. > + * @folio: Folio to add. > + * @len: How many bytes from the folio to add. > + * @off: First byte in this folio to add. > + * > + * Always uses the head page of the folio in the bio. If a submitter > + * only uses bio_add_folio(), it can count on never seeing tail pages > + * in the completion routine. BIOs do not support folios larger than 2GiB. > + * > + * Return: The number of bytes from this folio added to the bio. > + */ > +size_t bio_add_folio(struct bio *bio, struct folio *folio, size_t len, > + size_t off) > +{ > + if (len > UINT_MAX || off > UINT_MAX) Er... if bios don't support folios larger than 2GB, then why check @off and @len against UINT_MAX, which is ~4GB? --D > + return 0; > + return bio_add_page(bio, &folio->page, len, off); > +} > + > void bio_release_pages(struct bio *bio, bool mark_dirty) > { > struct bvec_iter_all iter_all; > diff --git a/include/linux/bio.h b/include/linux/bio.h > index 2203b686e1f0..ade93e2de6a1 100644 > --- a/include/linux/bio.h > +++ b/include/linux/bio.h > @@ -462,7 +462,8 @@ extern void bio_uninit(struct bio *); > extern void bio_reset(struct bio *); > void bio_chain(struct bio *, struct bio *); > > -extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); > +int bio_add_page(struct bio *, struct page *, unsigned len, unsigned off); > +size_t bio_add_folio(struct bio *, struct folio *, size_t len, size_t off); > extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *, > unsigned int, unsigned int); > int bio_add_zone_append_page(struct bio *bio, struct page *page, > -- > 2.30.2 >