From 1cde66165aac222f1a07ad4c3873c61d49eabb02 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Mon, 9 Jul 2012 15:23:52 +0100
Subject: fuse: Document race condition possible with fusermount.

See also:
https://bugzilla.redhat.com/show_bug.cgi?id=835466#c9
---
 fuse/guestmount.pod | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fuse/guestmount.pod b/fuse/guestmount.pod
index a0bc6f14..c37301c9 100644
--- a/fuse/guestmount.pod
+++ b/fuse/guestmount.pod
@@ -106,6 +106,22 @@ namespace using the Linux-specific L<clone(2)>/L<unshare(2)> flag
 C<CLONE_NEWNS>.  Unfortunately at the moment this requires root and we
 would also probably need to add it as a feature to guestmount.
 
+=head2 Race conditions possible when shutting down the connection
+
+When C<fusermount -u> exits, guestmount may still be running and
+cleaning up the mountpoint.  The disk image will not be fully
+finalized.
+
+This means that scripts like the following have a nasty race
+condition:
+
+ guestmount -a disk.img -i /mnt
+ # copy things into /mnt
+ fusermount -u /mnt
+ # immediately try to use 'disk.img' <-- UNSAFE
+
+The solution is to spin waiting for the guestmount process to exit.
+
 =head1 OPTIONS
 
 =over 4
-- 
cgit