Date: Tue, 2 Mar 2021 08:50:31 +0100 From: Arrigo Marchiori <ardovm@yahoo.it> To: freebsd-stable@freebsd.org Subject: Re: Trying do mount a slice containing a r/o mounted partition makes the filesystem unreadable Message-ID: <YD3uRz5wgf9lmvPH@nuvolo> In-Reply-To: <YDpmnBNO9J4e1p4C@nuvolo> References: <YDpCaI/sNgHcf08n@nuvolo> <202102271443.11REhqps070102@nuc.oldach.net> <YDpmnBNO9J4e1p4C@nuvolo>
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Dear All,
On Sat, Feb 27, 2021 at 04:34:52PM +0100, Arrigo Marchiori via freebsd-stable wrote:
> Hello Helge, and thank you for replying again.
>
> On Sat, Feb 27, 2021 at 03:43:52PM +0100, Helge Oldach wrote:
>
> > Arrigo Marchiori via freebsd-stable wrote on Sat, 27 Feb 2021 14:00:24 +0100 (CET):
> > > On the memstick, the root filesystem is mounted read-only. I
> > > apologize, I should have told it explicitly. The ``invalid'' attempt
> > > is to mount it read-write (no mode is indicated on the command line).
> >
> > Try to make it r/w mounted (which I suspect you are attempting to
> > achieve):
> >
> > mount -uw /
>
> Ok, I will try this.
>
> But just for the record: I am not try to achieve anything. I gave the
> ``invalid'' mount command by mistake (I wanted to mount a partition
> from another disk and wrote "da0" instead of "da1") and I saw that the
> system became unstable. I thought that this should not happen and I
> reported it here.
I have two updates.
1- the da0s2a slice starts 16 (blocks?) after the beginning of da0s2.
bsdlabel(8) output (copied by hand):
# /dev/da0s2:
8 partitions:
# size offset fstype [fsize bsize bps/cpg]
a: 1491200 16 4.2BSD 0 0 0
c: 1491216 0 unused 0 0 # "raw" part, don't edit
2- if I mount the partition rw, then the mount command _always_ fails
with error "operation not permitted" and the system _always_ remains
stable. This is independent from mounting from /dev/ufs/label or
/dev/da0s2a.
Therefore I can change the description of this problem report as:
----8<--------8<--------8<--------8<--------8<--------8<--------8<---------
When a BSD partition is mounted _read_only_ to / (suppose
/dev/da0s2a), if I try to mount its containing slice (/dev/da0s2) I
receive a ``strange'' error message, and from that moment the mounted
filesystem becomes unreadable.
- If the partition is mounted from /dev/ufs/label, then mount(8)
reports "Operation not permitted" and the system remains stable.
This is the expected behavior IMHO.
- If the partition is mounted read_write, from any special device,
then mount(8) reports:
- "Operation not permitted" if I try to mount the slice rw,
- the same strange error message if I try to mount the slice ro,
and the system remains stable.
- The "strange error message" is "invalid argument" on 11.4-STABLE.
----8<--------8<--------8<--------8<--------8<--------8<--------8<---------
Now to the question: is this worth a PR? Was it already reported? Or
is it just something that ``should not happen'' because root should be
allowed to shoot themselves in the foot?
Thank you in advance and best regards,
--
Arrigo
http://rigo.altervista.org
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