Date: Mon, 5 Jun 2006 22:34:32 +0200 From: Bastiaan Welmers <bastiaanpu@welmers.net> To: freebsd-fs@freebsd.org Subject: execution from unionfs issue Message-ID: <20060605203432.GA21420@routeduvel.rembrandtkd.welmers.net>
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Hi, I was wondering the following behavior from a unionfs mounted tree was normal or a bug: When mounting a tree on a directory as lower layer and I execute a binary from the lower layer, it will create a non-executable copy of the binary file on the upper layer: # mkdir /tmp/bin # mount -t unionfs -o -b /bin /tmp/bin # cd /tmp/bin # ./ls -l .... -r-xr-xr-x 1 root wheel 24232 30 mei 04:06 ls # ./ls -l ./ls: Permission denied # /bin/ls -l .... -rw-r--r-- 1 root wheel 24232 5 jun 22:23 ls # cd / # umount /tmp/bin # ls -l /tmp/bin -rw-r--r-- 1 root wheel 24232 5 jun 22:23 ls using -b or not (inversing upper/lower layer or not) does not matter, without -b same problem (when mounting /tmp/bin on /bin this time). It look likes when executing files it will try to open it read-write or something (for updating access time?) and unionfs creates a new (non-executable) copy on the upper layer. I don't know this is desirable behavior or not in general, to me it isn't at least. (I use it to provide basic userland for jails) I found the "noatime" mount option helps to resolve the problem, but I can't find this in any documentation. I'm using FreeBSD 6.1-RELEASE i386 GENERIC. /Bastiaan
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