[pkg-cryptsetup-devel] Bug#628038: Bug#628038: during shutdown, cannot mount root filesystem read-only

[Jonas Meurer]

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Hello James,

sorry for the late reply ...

Am 26.05.2011 17:08, schrieb jdietrch at fastmail.fm:
> After installing and setting up cryptsetup, I noticed that the root
> filesystem wasn't getting mounted read-only on shutdown anymore, thus
> causing it to be unclean on the next startup.
> 
> Specifically, one of the last messages printed to the screen during the
> shutdown sequence was now this:
> Mounting root filesystem read-only...mount: / is busy
> Failed
> 
> Then when the system was starting up again, fsck.reiserfs reported
> "Filesystem is NOT clean".
> 
> This was very repeatable, so I did some investigation.
> 
> I have just one device in my crypttab:
> # <target name> <source device>         <key file>      <options>
> name    /name.enc_vol    none   
> precheck=un_blkid,check=blkid,cipher=aes-cbc-essiv:sha256,size=256,hash=ripemd160
> 
> So I was surprised to discover *two* loopback devices configured:
> 
> saturn:/home/jdietrch# losetup -a
> /dev/loop0: [0801]:15801 (/name.enc_vol)
> /dev/loop1: [0801]:15801 (/name.enc_vol)
> saturn:/home/jdietrch# 
> 
> Further investigation revealed the reason: The function
> handle_crypptab_line_start() checks to make sure the target device
> doesn't exist. If it does exist, the function exits with "return 0". But
> it doesn't remove the loopback device that was set up earlier in the
> function. So I added a call rm_lo_setup just before the "return 0" and
> now I only have one loopback device as expected:
> 
> saturn:/home/jdietrch# losetup -a
> /dev/loop0: [0801]:15801 (/name.enc_vol)
> saturn:/home/jdietrch# 
> 
> Also, the message at the end of the shutdown sequence now says this:
> Mounting root filesystem read-only...done
> 
> And when the system starts up again, fsck.reiserfs reports that the
> "Filesystem is clean"
>
> Here is the change I made as a patch:
> 
> --- cryptdisks.functions.original       2011-03-11 04:05:53.000000000
> -0500
> +++ cryptdisks.functions        2011-05-26 10:46:18.000000000 -0400
> @@ -556,6 +556,7 @@
>  	# Make sure that target device doesn't exist
>  	if [ -b "/dev/mapper/${dst}_unformatted" ] || [ -b
>  	"/dev/mapper/$dst" ]; then
>  		device_msg "$dst" "running"
> +               rm_lo_setup
>  		return 0
>  	fi
>  
> I don't know if this is the correct or best way to fix problem noted at
> the beginning of this message, but in any case cryptsetup shouldn't
> prevent the system from shutting down cleanly.
> 
> In case it matters, my system is running up-to-date squeeze.
> 
> Let me know if you need any more information, or if there is anything
> else I can do to help.

Thanks a lot for this investigation. But the cryptsetup package changed
the way it handles loopback devices in the meantime. Upstream cryptsetup
has loopback support integrated since version 1.2.0. Therefore, I
removed all loopback-code from the Debian-specific scripts. Please give
the cryptsetup packages from Debian/testing a try, and see, whether it
fixes the problems for you. Unfortunately it's not possible to install
them flawlessly on Debian/Squeeze. In case that you don't have the
possibility to test a Debian/testing system, I can prepare cryptsetup
packages for you which work on Debian/Squeeze.

Greetings,
 jonas
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