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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, TVD_PH_BODY_ACCOUNTS_PRE 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 AB351C3F2D1 for ; Thu, 5 Mar 2020 18:05:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B27E2072D for ; Thu, 5 Mar 2020 18:05:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="D5Atr4/y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726067AbgCESFi (ORCPT ); Thu, 5 Mar 2020 13:05:38 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:34191 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726049AbgCESFh (ORCPT ); Thu, 5 Mar 2020 13:05:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583431535; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WX1nYbtFAYpqdVwieVgYRevSAmWyJkwdlAk/to/+48M=; b=D5Atr4/y3lw6s31DDd6wGz7xblVKvH4eTJ3cucRR92LX3LDO6j+iDini11Qqhx8rh2h7/5 JGI7a67AuplEfPlbcOfiWdvLutZM8EQ/5pzNfvrUwqMtOsDxSl4l/yR6Q6clsTzDe2bSAP kxF3ts/pbrtU704R9Xw60OI7A7o6OEU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-408-YUTPX9UjNBu6NHWFOADWSA-1; Thu, 05 Mar 2020 13:05:34 -0500 X-MC-Unique: YUTPX9UjNBu6NHWFOADWSA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 55B56184C805; Thu, 5 Mar 2020 18:05:33 +0000 (UTC) Received: from bfoster (dhcp-41-2.bos.redhat.com [10.18.41.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 049E19CA3; Thu, 5 Mar 2020 18:05:32 +0000 (UTC) Date: Thu, 5 Mar 2020 13:05:31 -0500 From: Brian Foster To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 01/11] xfs: don't try to write a start record into every iclog Message-ID: <20200305180531.GA28340@bfoster> References: <20200304075401.21558-1-david@fromorbit.com> <20200304075401.21558-2-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200304075401.21558-2-david@fromorbit.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed, Mar 04, 2020 at 06:53:51PM +1100, Dave Chinner wrote: > From: Dave Chinner > > The xlog_write() function iterates over iclogs until it completes > writing all the log vectors passed in. The ticket tracks whether > a start record has been written or not, so only the first iclog gets > a start record. We only ever pass single use tickets to > xlog_write() we only ever need to write a start record once per ^ "so we only ever ..." ? > xlog_write() call. > > Hence we don't need to store whether we should write a start record > in the ticket as the callers provide all the information we need to > determine if a start record should be written. For the moment, we > have to ensure that we clear the XLOG_TIC_INITED appropriately so > the code in xfs_log_done() still works correctly for committing > transactions. > > Signed-off-by: Dave Chinner > --- > fs/xfs/xfs_log.c | 68 +++++++++++++++++++++++++----------------------- > 1 file changed, 35 insertions(+), 33 deletions(-) > > diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c > index f6006d94a581..5b0568a86c07 100644 > --- a/fs/xfs/xfs_log.c > +++ b/fs/xfs/xfs_log.c ... > @@ -2404,25 +2391,29 @@ xlog_write( > int record_cnt = 0; > int data_cnt = 0; > int error = 0; > + int start_rec_size = sizeof(struct xlog_op_header); > > *start_lsn = 0; > > - len = xlog_write_calc_vec_length(ticket, log_vector); > > /* > * Region headers and bytes are already accounted for. > * We only need to take into account start records and > * split regions in this function. > */ > - if (ticket->t_flags & XLOG_TIC_INITED) > + if (ticket->t_flags & XLOG_TIC_INITED) { > ticket->t_curr_res -= sizeof(xlog_op_header_t); > + ticket->t_flags &= ~XLOG_TIC_INITED; > + } > > /* > * Commit record headers need to be accounted for. These > * come in as separate writes so are easy to detect. > */ > - if (flags & (XLOG_COMMIT_TRANS | XLOG_UNMOUNT_TRANS)) > + if (flags & (XLOG_COMMIT_TRANS | XLOG_UNMOUNT_TRANS)) { > ticket->t_curr_res -= sizeof(xlog_op_header_t); > + start_rec_size = 0; > + } This is more of a flaw in the existing code than this patch, but please update the comment to document why we reset start_rec_size here since it's not obvious from the context of the function. Otherwise looks Ok to me modulo Christoph's comments (in particular the data_cnt bit). My one nit is that I think start_rec might be a better name than start_rec_size given how it's used, but I don't care that much. Brian > > if (ticket->t_curr_res < 0) { > xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES, > @@ -2431,6 +2422,8 @@ xlog_write( > xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR); > } > > + len = xlog_write_calc_vec_length(ticket, log_vector, start_rec_size); > + > index = 0; > lv = log_vector; > vecp = lv->lv_iovecp; > @@ -2446,9 +2439,20 @@ xlog_write( > ASSERT(log_offset <= iclog->ic_size - 1); > ptr = iclog->ic_datap + log_offset; > > - /* start_lsn is the first lsn written to. That's all we need. */ > + /* > + * Before we start formatting log vectors, we need to write a > + * start record and record the lsn of the iclog that we write > + * the start record into. Only do this for the first iclog we > + * write to. > + */ > if (!*start_lsn) > *start_lsn = be64_to_cpu(iclog->ic_header.h_lsn); > + if (start_rec_size) { > + xlog_write_start_rec(ptr, ticket); > + xlog_write_adv_cnt(&ptr, &len, &log_offset, > + start_rec_size); > + record_cnt++; > + } > > /* > * This loop writes out as many regions as can fit in the amount > @@ -2457,7 +2461,6 @@ xlog_write( > while (lv && (!lv->lv_niovecs || index < lv->lv_niovecs)) { > struct xfs_log_iovec *reg; > struct xlog_op_header *ophdr; > - int start_rec_copy; > int copy_len; > int copy_off; > bool ordered = false; > @@ -2473,13 +2476,6 @@ xlog_write( > ASSERT(reg->i_len % sizeof(int32_t) == 0); > ASSERT((unsigned long)ptr % sizeof(int32_t) == 0); > > - start_rec_copy = xlog_write_start_rec(ptr, ticket); > - if (start_rec_copy) { > - record_cnt++; > - xlog_write_adv_cnt(&ptr, &len, &log_offset, > - start_rec_copy); > - } > - > ophdr = xlog_write_setup_ophdr(log, ptr, ticket, flags); > if (!ophdr) > return -EIO; > @@ -2509,10 +2505,15 @@ xlog_write( > xlog_write_adv_cnt(&ptr, &len, &log_offset, > copy_len); > } > - copy_len += start_rec_copy + sizeof(xlog_op_header_t); > + copy_len += sizeof(xlog_op_header_t); > record_cnt++; > data_cnt += contwr ? copy_len : 0; > > + if (start_rec_size) { > + copy_len += start_rec_size; > + start_rec_size = 0; > + } > + > error = xlog_write_copy_finish(log, iclog, flags, > &record_cnt, &data_cnt, > &partial_copy, > @@ -2550,6 +2551,7 @@ xlog_write( > break; > } > } > + start_rec_size = 0; > } > > ASSERT(len == 0); > -- > 2.24.0.rc0 >