From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754556AbeE1KG0 (ORCPT ); Mon, 28 May 2018 06:06:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:54208 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932118AbeE1KGR (ORCPT ); Mon, 28 May 2018 06:06:17 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, mulhern , Mike Snitzer , Sasha Levin Subject: [PATCH 3.18 016/185] dm thin: fix documentation relative to low water mark threshold Date: Mon, 28 May 2018 12:00:57 +0200 Message-Id: <20180528100051.583307137@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100050.700971285@linuxfoundation.org> References: <20180528100050.700971285@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: mulhern [ Upstream commit 9b28a1102efc75d81298198166ead87d643a29ce ] Fixes: 1. The use of "exceeds" when the opposite of exceeds, falls below, was meant. 2. Properly speaking, a table can not exceed a threshold. It emphasizes the important point, which is that it is the userspace daemon's responsibility to check for low free space when a device is resumed, since it won't get a special event indicating low free space in that situation. Signed-off-by: mulhern Signed-off-by: Mike Snitzer Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- Documentation/device-mapper/thin-provisioning.txt | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -112,9 +112,11 @@ $low_water_mark is expressed in blocks o free space on the data device drops below this level then a dm event will be triggered which a userspace daemon should catch allowing it to extend the pool device. Only one such event will be sent. -Resuming a device with a new table itself triggers an event so the -userspace daemon can use this to detect a situation where a new table -already exceeds the threshold. + +No special event is triggered if a just resumed device's free space is below +the low water mark. However, resuming a device always triggers an +event; a userspace daemon should verify that free space exceeds the low +water mark when handling this event. A low water mark for the metadata device is maintained in the kernel and will trigger a dm event if free space on the metadata device drops below