From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 03/12] blkcg: convert blkg_lookup_create to find closest blkg Date: Tue, 11 Sep 2018 16:50:09 -0700 Message-ID: <20180911235009.GC2966370@devbig004.ftw2.facebook.com> References: <20180911184137.35897-1-dennisszhou@gmail.com> <20180911184137.35897-4-dennisszhou@gmail.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=eA1Y8LAM4afbJQHN/Q+Ti6OaqCzYueF4LckPdLkAuEQ=; b=hO5rT3hbXcIWtGDs3OyFendQ0YC+UFVYXBBAz8vglQuSdKZ4XKCHjxdrX5nhMfN1Rz JzEO3vKitQt3NGra8UI+JbeG4/eawXZ+wQJx74BERbdBuzteccrfAonWna6WzxgyyI6g /ZfKD1lTmDsw6wfcv2gi32lk5swJBb3TAbsbxrwHuhxyP6wr0lCx6HUY2iXIwwvEfz/p /iSQYQb0QbqfGeRP1SqPZK9PecU3YAQJwPv9ms4tVbJ42TjaUnB+aTfYF5x7NxOBfBcA sjv+1Z8epTLmj8sRa+tmF2Nq76HRo9dyA4fYv3GMX1Tgxe71LcwUHSjwEUsXF6vIdC75 344Q== Content-Disposition: inline In-Reply-To: <20180911184137.35897-4-dennisszhou@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dennis Zhou Cc: Jens Axboe , Johannes Weiner , Josef Bacik , kernel-team@fb.com, linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org On Tue, Sep 11, 2018 at 02:41:28PM -0400, Dennis Zhou wrote: > From: "Dennis Zhou (Facebook)" > > There are several scenarios where blkg_lookup_create can fail. Examples > include the blkcg dying, request_queue is dying, or simply being OOM. At > the end of the day, most handle this by simply falling back to the > q->root_blkg and calling it a day. > > This patch implements the notion of closest blkg. During > blkg_lookup_create, if it fails to create, return the closest blkg > found or the q->root_blkg. blkg_try_get_closest is introduced and used > during association so a bio is always attached to a blkg. > > Signed-off-by: Dennis Zhou Acked-by: Tejun Heo Thanks. -- tejun