From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-by2nam01on0100.outbound.protection.outlook.com ([104.47.34.100]:3232 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932894AbeDIAh4 (ORCPT ); Sun, 8 Apr 2018 20:37:56 -0400 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: mulhern , Mike Snitzer , Sasha Levin Subject: [PATCH AUTOSEL for 4.4 116/162] dm thin: fix documentation relative to low water mark threshold Date: Mon, 9 Apr 2018 00:29:14 +0000 Message-ID: <20180409002738.163941-116-alexander.levin@microsoft.com> References: <20180409002738.163941-1-alexander.levin@microsoft.com> In-Reply-To: <20180409002738.163941-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: 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 --- Documentation/device-mapper/thin-provisioning.txt | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentat= ion/device-mapper/thin-provisioning.txt index 1699a55b7b70..ef639960b272 100644 --- 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 of size $data_b= lock_size. If 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 bel= ow +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. =20 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 --=20 2.15.1