From 0ae2aa6a43a852cb0326faade1532c02aa7617a4 Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Fri, 20 Apr 2018 09:50:04 +0200 Subject: [PATCH 156/173] umount: add note about --lazy Unfortunately, it's pretty common that users on production systems use lazy umount to fix some FS issues. The usual result is unwanted system reboot, because -l is not the right way how to fix unreachable NFS or mess with local FS with submounts. Note that after lazy umount /proc/self/mountinfo does not contain the FS entry, but kernel still references the FS. It makes it very difficult to debug. Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1566674 Suggested-by: Steve Dickson Signed-off-by: Karel Zak Upstream: http://github.com/karelzak/util-linux/commit/031800ff6c66b4d62229cfd116195950a718a21c --- sys-utils/umount.8 | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/sys-utils/umount.8 b/sys-utils/umount.8 index f0a712b06..71c2155b4 100644 --- a/sys-utils/umount.8 +++ b/sys-utils/umount.8 @@ -54,7 +54,8 @@ working directory there, or when a swap file on it is in use. The offending process could even be .B umount itself - it opens libc, and libc in its turn may open for example locale -files. A lazy unmount avoids this problem. +files. A lazy unmount avoids this problem, but it may introduce another +issues. See \fB\-\-lazy\fR description bellow. .SH OPTIONS .TP \fB\-a\fR, \fB\-\-all\fR @@ -107,6 +108,13 @@ Unmount without writing in Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.) + +A system reboot would be expected in near future if you're going to use this +option for network filesystem or local filesystem with submounts. The +recommended use-case for \fBumount -l\fR is to prevent hangs on shutdown due to +an unreachable network share where a normal umount will hang due to a downed +server or a network partition. Remounts of the share will not be possible. + .TP \fB\-O\fR, \fB\-\-test\-opts\fR \fIoptions,list\fR Indicate that the actions should only be taken on file systems with the -- 2.14.4