From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752817AbeE3LMP (ORCPT ); Wed, 30 May 2018 07:12:15 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60759 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752062AbeE3LHi (ORCPT ); Wed, 30 May 2018 07:07:38 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "mulhern" , "Mike Snitzer" Date: Wed, 30 May 2018 11:52:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 052/153] dm thin: fix documentation relative to low water mark threshold In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.102-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: mulhern commit 9b28a1102efc75d81298198166ead87d643a29ce upstream. 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: Ben Hutchings --- 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 @@ -109,9 +109,11 @@ $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. Thin provisioning -----------------