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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 1F19AC4338F for ; Tue, 27 Jul 2021 12:46:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9A3B60234 for ; Tue, 27 Jul 2021 12:46:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232002AbhG0Mq6 (ORCPT ); Tue, 27 Jul 2021 08:46:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231971AbhG0Mq5 (ORCPT ); Tue, 27 Jul 2021 08:46:57 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26305C061757 for ; Tue, 27 Jul 2021 05:46:57 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id mz5-20020a17090b3785b0290176ecf64922so4033504pjb.3 for ; Tue, 27 Jul 2021 05:46:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=eiHEMQDUaHOsVqdoai/5mCr3sUUZYfdJgbkg4RX7QLc=; b=k3zXkWuSQE9PsWy5eYh0+v6YTJJ71EYHFUQshi9pTiVlsoweMm1aTl/6H9gcNOg/g0 U7WhjP+XWmM7FB+JENAUyOs/MNkGcqYy/pd6x/e0gSrze+rlS9FhazHc//3uAGqaj9Wd I2Kl/gWUX0qK5Q60wxy8GS0SFM+WceB0AwMhQ1P+mG0qqhK0oKeelXNy4bgjFab/ig9n zZtcxW/NUe4ElsHNJaySZxQaUaUeuK//6CRKItnbRKinm6oC3QHaCXDRDRxHpUjvqGPN PAbpm8R7V9uvY8/W6uIAHsJc3ZraDS8BI8d9B7CqvoZlIZJkBkytAyvVw046Xtxr+7ua zX3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=eiHEMQDUaHOsVqdoai/5mCr3sUUZYfdJgbkg4RX7QLc=; b=jYfR8GlL57ElpqzMQGcg+iJMc3PTf4xayeBICWVR8R/SAEhOxPqsKU9stmMYyjKBm/ 8A6OS8NgJjexAYhUbdpzxHw1KR/gXSb/5qHWQSgno87zGiC6C7pfRE/n8JFVncZNujWo +A9WE8tnNSGIPdHvxp0s60v9VJF1sIC2JcfhtIu0sGXpuQGQnvwjB7Jk3DjHLzMuLqda AmzitUOkFZpYwRsQeXuLHRoTFuV5Mi/nKtl00FMiyJ37WgtbwRBIFVcVd7eMrxv/cQzI Hs86+XUPRZ9iqIwkvnylIYTWnWN9UHsrI4JMjGJQXLcC8ZN8VPDCqoQNkAcWPR7+cBsU BPmA== X-Gm-Message-State: AOAM532gnGt3lwBdL/7epuwqMJk99vMv/UT/MhC/3M6S3Cg/2WsPNNV2 lgUYFy0Rd2WGGJkvVbqwZSt/s+j/Qi0= X-Google-Smtp-Source: ABdhPJw7IYPFY3s0NKLhvG0xruaVqESONs1h6vntzFOeYf1Lh3dALQrx1cO249vwikq1NmAqSzEeNA== X-Received: by 2002:a17:90a:fb85:: with SMTP id cp5mr19703250pjb.214.1627390016499; Tue, 27 Jul 2021 05:46:56 -0700 (PDT) Received: from garuda ([122.171.185.191]) by smtp.gmail.com with ESMTPSA id o9sm3905506pfh.217.2021.07.27.05.46.55 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 27 Jul 2021 05:46:56 -0700 (PDT) References: <20210727062053.11129-1-allison.henderson@oracle.com> <20210727062053.11129-3-allison.henderson@oracle.com> User-agent: mu4e 1.0; emacs 26.1 From: Chandan Babu R To: Allison Henderson Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH v22 02/16] xfs: clear log incompat feature bits when the log is idle In-reply-to: <20210727062053.11129-3-allison.henderson@oracle.com> Date: Tue, 27 Jul 2021 18:16:53 +0530 Message-ID: <87a6m7gc02.fsf@garuda> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On 27 Jul 2021 at 11:50, Allison Henderson wrote: > From: "Darrick J. Wong" > > When there are no ongoing transactions and the log contents have been > checkpointed back into the filesystem, the log performs 'covering', > which is to say that it log a dummy transaction to record the fact that > the tail has caught up with the head. This is a good time to clear log > incompat feature flags, because they are flags that are temporarily set > to limit the range of kernels that can replay a dirty log. > > Since it's possible that some other higher level thread is about to > start logging items protected by a log incompat flag, we create a rwsem > so that upper level threads can coordinate this with the log. It would > probably be more performant to use a percpu rwsem, but the ability to > /try/ taking the write lock during covering is critical, and percpu > rwsems do not provide that. > Looks good to me. Reviewed-by: Chandan Babu R > Signed-off-by: Darrick J. Wong > Reviewed-by: Allison Henderson > Signed-off-by: Allison Henderson > --- > fs/xfs/xfs_log.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ > fs/xfs/xfs_log.h | 3 +++ > fs/xfs/xfs_log_priv.h | 3 +++ > 3 files changed, 55 insertions(+) > > diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c > index 9254405..c58a0d7 100644 > --- a/fs/xfs/xfs_log.c > +++ b/fs/xfs/xfs_log.c > @@ -1338,6 +1338,32 @@ xfs_log_work_queue( > } > > /* > + * Clear the log incompat flags if we have the opportunity. > + * > + * This only happens if we're about to log the second dummy transaction as part > + * of covering the log and we can get the log incompat feature usage lock. > + */ > +static inline void > +xlog_clear_incompat( > + struct xlog *log) > +{ > + struct xfs_mount *mp = log->l_mp; > + > + if (!xfs_sb_has_incompat_log_feature(&mp->m_sb, > + XFS_SB_FEAT_INCOMPAT_LOG_ALL)) > + return; > + > + if (log->l_covered_state != XLOG_STATE_COVER_DONE2) > + return; > + > + if (!down_write_trylock(&log->l_incompat_users)) > + return; > + > + xfs_clear_incompat_log_features(mp); > + up_write(&log->l_incompat_users); > +} > + > +/* > * Every sync period we need to unpin all items in the AIL and push them to > * disk. If there is nothing dirty, then we might need to cover the log to > * indicate that the filesystem is idle. > @@ -1363,6 +1389,7 @@ xfs_log_worker( > * synchronously log the superblock instead to ensure the > * superblock is immediately unpinned and can be written back. > */ > + xlog_clear_incompat(log); > xfs_sync_sb(mp, true); > } else > xfs_log_force(mp, 0); > @@ -1450,6 +1477,8 @@ xlog_alloc_log( > } > log->l_sectBBsize = 1 << log2_size; > > + init_rwsem(&log->l_incompat_users); > + > xlog_get_iclog_buffer_size(mp, log); > > spin_lock_init(&log->l_icloglock); > @@ -3895,3 +3924,23 @@ xfs_log_in_recovery( > > return log->l_flags & XLOG_ACTIVE_RECOVERY; > } > + > +/* > + * Notify the log that we're about to start using a feature that is protected > + * by a log incompat feature flag. This will prevent log covering from > + * clearing those flags. > + */ > +void > +xlog_use_incompat_feat( > + struct xlog *log) > +{ > + down_read(&log->l_incompat_users); > +} > + > +/* Notify the log that we've finished using log incompat features. */ > +void > +xlog_drop_incompat_feat( > + struct xlog *log) > +{ > + up_read(&log->l_incompat_users); > +} > diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h > index 813b972..b274fb9 100644 > --- a/fs/xfs/xfs_log.h > +++ b/fs/xfs/xfs_log.h > @@ -142,4 +142,7 @@ bool xfs_log_in_recovery(struct xfs_mount *); > > xfs_lsn_t xlog_grant_push_threshold(struct xlog *log, int need_bytes); > > +void xlog_use_incompat_feat(struct xlog *log); > +void xlog_drop_incompat_feat(struct xlog *log); > + > #endif /* __XFS_LOG_H__ */ > diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h > index 4c41bbfa..c507041 100644 > --- a/fs/xfs/xfs_log_priv.h > +++ b/fs/xfs/xfs_log_priv.h > @@ -449,6 +449,9 @@ struct xlog { > xfs_lsn_t l_recovery_lsn; > > uint32_t l_iclog_roundoff;/* padding roundoff */ > + > + /* Users of log incompat features should take a read lock. */ > + struct rw_semaphore l_incompat_users; > }; > > #define XLOG_BUF_CANCEL_BUCKET(log, blkno) \ -- chandan