From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:57656 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751311AbeCESxG (ORCPT ); Mon, 5 Mar 2018 13:53:06 -0500 Date: Mon, 5 Mar 2018 10:52:59 -0800 From: "Darrick J. Wong" Subject: Re: [PATCH] xfs: Correctly invert xfs_buftarg LRU isolation logic Message-ID: <20180305185259.GC18989@magnolia> References: <20180228154951.31714-1-vbendel@redhat.com> <20180301224800.GI12763@magnolia> <20180302163603.GQ19312@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Vratislav Bendel Cc: linux-xfs@vger.kernel.org, Brian Foster , linux-kernel@vger.kernel.org, djwong@kernel.org On Mon, Mar 05, 2018 at 11:19:46AM +0100, Vratislav Bendel wrote: > (In response to Luis' comment:) > > Can you add a respective Fixes: tag? > > It was apparently present since LRU was added to xfs buffer cache via: > commit 430cbeb86fdcbbdabea7d4aa65307de8de425350 > [xfs: add a lru to the XFS buffer cache] > > But I wouldn't say this patch "fixes" that commit. > What do you think? Should a fixes tag be added in this case? > > > > Also what effects are observed by > > the user when this happens on the kernel log? > > I haven't spotted any differences visible to user, nor in the kernel log. > > (In response to Brian's comment:) > >> However, as per documentation, atomic_add_unless() returns _zero_ > >> if the atomic value was originally equal to the specified *unsless* value. > >> > > Nit: unless > > Thanks very much for feedback. Since it's my very first upstream > commit-proposal, > I expected that some polish would be needed. > > > > It might be worth pointing out in the commit log that currently isolated > > buffers end up right back on the LRU once they are released, because > > ->b_lru_ref remains elevated. Therefore, this patch essentially fixes > > that circuitous route by leaving them on the LRU as originally intended. > > Otherwise this looks Ok to me: > > So the final commit message could be: > ~~~ > Currently the xfs_buftarg_isolate() is causing an xfs_buffer "Due to an inverted logic mistake in xfs_buftarg_isolate()..."? > with zero b_lru_ref, to take another trip around LRU, while ^^^^ no need for this comma > isolating buffers with non-zero b_lru_ref. > > Additionally those isolated buffers end up right back on the LRU > once they are released, because ->b_lru_ref remains elevated. > > Fix that circuitous route by leaving them on the LRU > as originally intended. Otherwise this seems fine to me; can you please resend the patch w/ updated change log and reviewed-by tags? Reviewed-by: Darrick J. Wong --D > > >> Signed-off-by: Vratislav Bendel > > Reviewed-by: Brian Foster > > --- > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html