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=-16.3 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=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 88036C433E0 for ; Tue, 9 Mar 2021 02:15:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4B13C65290 for ; Tue, 9 Mar 2021 02:15:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229694AbhCICO5 (ORCPT ); Mon, 8 Mar 2021 21:14:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:41712 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229611AbhCICOu (ORCPT ); Mon, 8 Mar 2021 21:14:50 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B14C5652A4; Tue, 9 Mar 2021 02:14:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615256089; bh=ywub+lOfD2UEjHE1HnuVmm/xAsMx6k3NGkUGa6HPj9A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iCrCx+Y2JXXlPaKl3jy6/mArbK1OF2lAvOEvQPrQZMTZSqxOW7DBmt/2Q3tSciqY/ Hb48gU8i9K8yYODVsoqKOJkn5C1s546kkvK30bWwyLajgWzMGsn4sLaJZeg32YkxrE FGZJNV+mCAWiOcp7Ng+x1mVyhwk5VDgOuVoPBwiInm/q+JuJ4Iad1pEyqEYFhvOUhe FLsBnx6ASqQhOpxLiOA2OuLedhfZwv+MAPKqojxxDAQ6/+SpsxKx9PDZzjCmY4q19O aqTLX8UdhpjxPOlUKZlWTYoDgRE954r1f3Ii5iagUek6VHOjIAxZELlORVg2zP3oCv bfpZnMZVVu2CQ== Date: Mon, 8 Mar 2021 18:14:48 -0800 From: "Darrick J. Wong" To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 24/45] xfs: move log iovec alignment to preparation function Message-ID: <20210309021448.GL3419940@magnolia> References: <20210305051143.182133-1-david@fromorbit.com> <20210305051143.182133-25-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210305051143.182133-25-david@fromorbit.com> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Fri, Mar 05, 2021 at 04:11:22PM +1100, Dave Chinner wrote: > From: Dave Chinner > > To include log op headers directly into the log iovec regions that > the ophdrs wrap, we need to move the buffer alignment code from > xlog_finish_iovec() to xlog_prepare_iovec(). This is because the > xlog_op_header is only 12 bytes long, and we need the buffer that > the caller formats their data into to be 8 byte aligned. > > Hence once we start prepending the ophdr in xlog_prepare_iovec(), we > are going to need to manage the padding directly to ensure that the > buffer pointer returned is correctly aligned. > > Signed-off-by: Dave Chinner > Reviewed-by: Christoph Hellwig Ok, now that I grok what's going on in the /next/ patch, this makes sense to me as the way into the next patch. Reviewed-by: Darrick J. Wong --D > --- > fs/xfs/xfs_log.h | 25 ++++++++++++++----------- > 1 file changed, 14 insertions(+), 11 deletions(-) > > diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h > index c0c3141944ea..1ca4f2edbdaf 100644 > --- a/fs/xfs/xfs_log.h > +++ b/fs/xfs/xfs_log.h > @@ -21,6 +21,16 @@ struct xfs_log_vec { > > #define XFS_LOG_VEC_ORDERED (-1) > > +/* > + * We need to make sure the buffer pointer returned is naturally aligned for the > + * biggest basic data type we put into it. We have already accounted for this > + * padding when sizing the buffer. > + * > + * However, this padding does not get written into the log, and hence we have to > + * track the space used by the log vectors separately to prevent log space hangs > + * due to inaccurate accounting (i.e. a leak) of the used log space through the > + * CIL context ticket. > + */ > static inline void * > xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp, > uint type) > @@ -34,6 +44,9 @@ xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp, > vec = &lv->lv_iovecp[0]; > } > > + if (!IS_ALIGNED(lv->lv_buf_len, sizeof(uint64_t))) > + lv->lv_buf_len = round_up(lv->lv_buf_len, sizeof(uint64_t)); > + > vec->i_type = type; > vec->i_addr = lv->lv_buf + lv->lv_buf_len; > > @@ -43,20 +56,10 @@ xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp, > return vec->i_addr; > } > > -/* > - * We need to make sure the next buffer is naturally aligned for the biggest > - * basic data type we put into it. We already accounted for this padding when > - * sizing the buffer. > - * > - * However, this padding does not get written into the log, and hence we have to > - * track the space used by the log vectors separately to prevent log space hangs > - * due to inaccurate accounting (i.e. a leak) of the used log space through the > - * CIL context ticket. > - */ > static inline void > xlog_finish_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec *vec, int len) > { > - lv->lv_buf_len += round_up(len, sizeof(uint64_t)); > + lv->lv_buf_len += len; > lv->lv_bytes += len; > vec->i_len = len; > } > -- > 2.28.0 >