Re: Device ... is still in use.

On Mon, Aug 19, 2019 at 9:46 AM Milan Broz <[email protected]> wrote:

> On 19/08/2019 15:23, Jean-Paul Calderone wrote:
> > On Mon, Aug 19, 2019 at 9:16 AM Milan Broz <[email protected] <mailto:
> [email protected]>> wrote:
> >
> >     On 19/08/2019 14:59, Jean-Paul Calderone wrote:
> >     > Hello,
> >     >
> >     > I have a luks device on removable media that has somehow become
> stuck on my system.  The physical media has been disconnected but the luks
> device continues to exist and I cannot remove it.
> >     >
> >     > cryptosetup close fails:
> >     >
> >     >     $ sudo cryptsetup close
> luks-64ca6f08-82c9-4571-a976-f37a83aca3b1
> >     >     Device luks-64ca6f08-82c9-4571-a976-f37a83aca3b1 is still in
> use.
> >     >
> >     >
> >     > I don't understand what is still using the device.  It is not
> mounted anywhere:
> >     >
> >     >     $ mount | grep luks-64ca6f08-82c9-4571-a976-f37a83aca3b1
> >
> >     See output of lsblk - it can have mapped partitions or lvm over it,
> >     you need to deactivate it.
> >
> >     Also check lsof output if some process is not stuck keeping
> something open there.
> >
> >
> > Thanks for the suggestion.  `lsblk --all` doesn't mention the device -
> either the mapped luks device or the underlying block device.  It mentions
> some ram devices, some loopback devices (but `losetup --all` says none are
> in use), and my internal storage devices.
>
> If you can see it as /dev/dm-0 and in /dev/mapper but lsblk does not show
> it, your system seems
> to be misconfigured (lsblk should read internal kernel state from sysfs).
>
> What says "dmsetup info -c" ?
>

$ sudo dmsetup info -c
Name                                      Maj Min Stat Open Targ Event
 UUID
luks-64ca6f08-82c9-4571-a976-f37a83aca3b1 254   0 L--w    1    1      0
CRYPT-LUKS1-64ca6f0882c94571a976f37a83aca3b1-luks-64ca6f08-82c9-4571-a976-f37a83aca3b1
$



>
> The /dev/dm-0 *is* the luks device itself (/dev/mapper/luks* should be
> symlink to it).
>
> Anyway, if you just need to remove it by force, use
>   dmsetup remove luks-64ca6f08-82c9-4571-a976-f37a83aca3b1
> if it still complains, add "--force" option - it will remap it to error
> target removing all references to underlying devices and keys.
>
> Also check syslog if there is any related message (crash or something that
> could explain it).
>

Looks like something bad going on at a lower level:

$ sudo dmsetup remove /dev/dm-0
device-mapper: remove ioctl on luks-64ca6f08-82c9-4571-a976-f37a83aca3b1
 failed: Device or resource busy
Command failed.
$ sudo dmsetup remove --force /dev/dm-0
device-mapper: remove ioctl on luks-64ca6f08-82c9-4571-a976-f37a83aca3b1
 failed: Device or resource busy
Command failed.
$ dmesg | tail -n 1
[1323040.325203] Buffer I/O error on dev dm-0, logical block 1968624, async
page read
$


And every `dmsetup remove --force` adds another `Buffer I/O error ...` like
the above.

Thanks,
Jean-Paul

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