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=-7.0 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 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 40EE7C43331 for ; Mon, 30 Mar 2020 12:15:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 08C0F20714 for ; Mon, 30 Mar 2020 12:15:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ne6rea0U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729900AbgC3MPu (ORCPT ); Mon, 30 Mar 2020 08:15:50 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:46399 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729867AbgC3MPu (ORCPT ); Mon, 30 Mar 2020 08:15:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585570549; 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=XIB3Kt4/Qz93A6/QQAEfG9SAR/UO9k/yyPLAYa54zXg=; b=Ne6rea0U4Q3MILETW3uAHEwuOAXsj/JbiNZixEao0n20Mrj5mY0oCuZTEmsum/lGPCjsew hTVlOSUz3PlbMAvb/NA6q6SL3MPsbKazERxHxBQUYDUlrK+ihpvZlH+ODj3kwH1eO6hrJW +K44D3XdqFli2SVxozLWnyxyPnQ8SNo= 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-286-T5CdNj-cPweEAG1-zuD2pg-1; Mon, 30 Mar 2020 08:15:47 -0400 X-MC-Unique: T5CdNj-cPweEAG1-zuD2pg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B73D119251A7; Mon, 30 Mar 2020 12:15:46 +0000 (UTC) Received: from bfoster (dhcp-41-2.bos.redhat.com [10.18.41.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 565F5194BB; Mon, 30 Mar 2020 12:15:46 +0000 (UTC) Date: Mon, 30 Mar 2020 08:15:44 -0400 From: Brian Foster To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 1/2] xfs: trylock underlying buffer on dquot flush Message-ID: <20200330121544.GA45961@bfoster> References: <20200326131703.23246-1-bfoster@redhat.com> <20200326131703.23246-2-bfoster@redhat.com> <20200329224602.GT10776@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200329224602.GT10776@dread.disaster.area> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Mon, Mar 30, 2020 at 09:46:02AM +1100, Dave Chinner wrote: > On Thu, Mar 26, 2020 at 09:17:02AM -0400, Brian Foster wrote: > > A dquot flush currently blocks on the buffer lock for the underlying > > dquot buffer. In turn, this causes xfsaild to block rather than > > continue processing other items in the meantime. Update > > xfs_qm_dqflush() to trylock the buffer, similar to how inode buffers > > are handled, and return -EAGAIN if the lock fails. Fix up any > > callers that don't currently handle the error properly. > > > > Signed-off-by: Brian Foster > > --- > > fs/xfs/xfs_dquot.c | 6 +++--- > > fs/xfs/xfs_dquot_item.c | 3 ++- > > fs/xfs/xfs_qm.c | 14 +++++++++----- > > 3 files changed, 14 insertions(+), 9 deletions(-) > > > > diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c > > index 711376ca269f..af2c8e5ceea0 100644 > > --- a/fs/xfs/xfs_dquot.c > > +++ b/fs/xfs/xfs_dquot.c > > @@ -1105,8 +1105,8 @@ xfs_qm_dqflush( > > * Get the buffer containing the on-disk dquot > > */ > > error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno, > > - mp->m_quotainfo->qi_dqchunklen, 0, &bp, > > - &xfs_dquot_buf_ops); > > + mp->m_quotainfo->qi_dqchunklen, XBF_TRYLOCK, > > + &bp, &xfs_dquot_buf_ops); > > if (error) > > goto out_unlock; > > > > @@ -1177,7 +1177,7 @@ xfs_qm_dqflush( > > > > out_unlock: > > xfs_dqfunlock(dqp); > > - return -EIO; > > + return error; > > } > > > > /* > > diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c > > index cf65e2e43c6e..baad1748d0d1 100644 > > --- a/fs/xfs/xfs_dquot_item.c > > +++ b/fs/xfs/xfs_dquot_item.c > > @@ -189,7 +189,8 @@ xfs_qm_dquot_logitem_push( > > if (!xfs_buf_delwri_queue(bp, buffer_list)) > > rval = XFS_ITEM_FLUSHING; > > xfs_buf_relse(bp); > > - } > > + } else if (error == -EAGAIN) > > + rval = XFS_ITEM_LOCKED; > > Doesn't xfs_inode_item_push() also have this problem in that it > doesn't handle -EAGAIN properly? > > Also, we can get -EIO, -EFSCORRUPTED, etc here. They probably > shouldn't return XFS_ITEM_SUCCESS, either.... > Good point. I'm actually not sure what we should return in that case given the item return codes all seem to assume a valid state. We could define an XFS_ITEM_ERROR return, but I'm not sure it's worth it for what is currently stat/tracepoint logic in the caller. Perhaps a broader rework of error handling in this context is in order that would lift generic (fatal) error handling into xfsaild. E.g., I see that xfs_qm_dqflush() is inconsistent by itself in that the item is removed from the AIL if we're already shut down, but not if that function invokes the shutdown; we shutdown if the direct xfs_dqblk_verify() call fails but not if the read verifier (which also looks like it calls xfs_dqblk_verify() on every on-disk dquot) returns -EFSCORRUPTED, etc. It might make some sense to let iop_push() return negative error codes if that facilitates consistent error handling... Brian > Otherwise seems OK. > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com >