Re: [Libguestfs] [PATCH v2v 2/2] convert: Remove /dev/mapper/osprober-* devices left around by grub2

On Tue, May 17, 2022 at 01:10:32PM +0200, Laszlo Ersek wrote: > On 05/17/22 12:59, Richard W.M. Jones wrote: >> These devices can be left around by grub2 when it runs the osprober >> tool after we run “/sbin/grub2-mkconfig -o /boot/grub2/grub.cfg”. >> They are read-only mirrors of existing filesystems. These confuse >> later steps in conversion, specifically fstrim. >> >> Reported-by: Ming Xie >> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2003503 >> --- >> convert/linux_bootloaders.ml | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/convert/linux_bootloaders.ml b/convert/linux_bootloaders.ml >> index a70b65a41c..7c5fb0be3f 100644 >> --- a/convert/linux_bootloaders.ml >> +++ b/convert/linux_bootloaders.ml >> @@ -345,7 +345,14 @@ object (self) >> method remove_console = self#grub2_update_console ~remove:true >> >> method update () = >> - ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config |]) >> + ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config |]); >> + >> + (* Grub2 runs osprober which sometimes leaves around read-only >> + * device-mapper maps covering existing filesystems. These >> + * confuse later steps (especially fstrim). So just delete >> + * any if found. (RHBZ#2003503). >> + *) >> + ignore (g#command [| "bash"; "-c"; "rm -f /dev/mapper/osprober-*" |]) >> >> method get_config_file () = >> grub_config >> > > Hmm... I'm not sure why this is better than "dmsetup remove", but it > does not really matter. We need these nodes to disappear only for the > remainder of the conversion -- so command that effects that suffices! > > Reviewed-by: Laszlo Ersek <lersek(a)redhat.com&gt; Yeah, I'm not really sure what I was thinking there. I certainly *meant* to use dmsetup remove, but maybe ... it's accidentally better? The problem with running dmsetup is that we have to run the guest command, which might not exist. Fun fact I found when investigating this. Upstream os-prober dropped the whole device mapper / dmsetup / osprober-linux-* stuff back in 2017.

The current code doesn't mention osprober-linux-* at all. So I guess the version in this RHEL 8 guest is quite old. Since I'm still testing the (above) version of this patch, let's see if "rm" actually works before doing any further work on this.