From 4cf25c27f89754e0e0310cb430dee0ddd9493c70 Mon Sep 17 00:00:00 2001 From: Nikolaus Rath Date: Tue, 4 Apr 2023 22:20:19 +0100 Subject: Document risks of auto_unmount (#763) --- doc/mount.fuse3.8 | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/doc/mount.fuse3.8 b/doc/mount.fuse3.8 index 0cb0b5c..230c6af 100644 --- a/doc/mount.fuse3.8 +++ b/doc/mount.fuse3.8 @@ -146,6 +146,21 @@ responsible for releasing the mountpoint, which means that the mountpoint becomes inaccessible if the filesystem terminates without first unmounting. +This option is dangerous and should only be used after careful consideration of the +risks. + +Automatically unmounting the filesystem means that if the filesystem crashes the +mountpoint may suddenly appear empty, which may have unintended consequences. For example, +a running backup and mirroring program may conclude that all the data in the filesystem +has been deleted and proceed to propagate this deletion to the backup / remote system. If +the mountpoint instead becomes inaccessible (the default), most programs will behave +correctly (report an error). + +This feature may also accidentally unmount the wrong filesystem due to race +conditions. For example, if another filesystem was mounted underneath the same mountpoint, +or if a new filesystem is mounted after the FUSE process has crashed, it may accidentally +get unmounted. + At the moment, this option implies that the filesystem will also be mounted with \fBnodev\fP and \fBnosuid\fP (even when mounted by root). This restriction may be lifted in the future. -- cgit v1.2.1