Write attempt to file in ZFS snapshot dir causes panic

[krad]

2009/10/20 Carl Chave <carl at chave.us>

> Does file o exist?  In my example I first try to create a new file
> which fails as expected.  I then try to append to an existing file
> which triggers the panic.
>
> On Tue, Oct 20, 2009 at 6:17 AM, krad <kraduk at googlemail.com> wrote:
> >
> >
> > 2009/10/19 Carl Chave <online at chave.us>
> >>
> >> I'm new to FreeBSD.  Been experimenting with 8.0-RC1 and zfs in a VM.
> >> Really haven't even installed it yet, just getting familiar with zfs
> >> usage from the fixit environment.  I experienced some strange behavior
> >> and was wondering if this would warrant a bug report:
> >>
> >> 1. load zfs from bootloader prompt and then boot.
> >> 2. enter fixit environment.
> >> 3. import zpool (in this case a 2 disk vmware mirror named sodpool)
> >> 4. cd to previously created snapshot at
> >> sodpool/test/myfs/.zfs/snapshot/one
> >> 5. attempting to create a new file here results in:
> >>
> >> Fixit# echo hello > hello.txt
> >> cannot create hello.txt: Read-only file system
> >>
> >> 6. That seems like the desired response.  Next, attempt to modify a
> >> file that already exists in the snapshot:
> >>
> >> Fixit# echo hello >> test.txt
> >> panic: dirtying snapshot!
> >>
> >> I know I'm not supposed to be modifying a snapshot file, but a panic
> >> doesn't seem like the best response to this situation.
> >>
> >> I'm using DVD iso named 8.0-RC1-amd64-dvd1.iso
> >>
> >> This bug report has the same panic but the scenario is different:
> >> http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/138764
> >>
> >> Is there someplace else I should check for existing issues?
> >> _______________________________________________
> >> freebsd-questions at freebsd.org mailing list
> >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> >> To unsubscribe, send any mail to
> >> "freebsd-questions-unsubscribe at freebsd.org"
> >
> >
> > I dont see these issues
> >
> > $ echo i > o
> > bash: o: Read-only file system
> > $ pwd
> > /usr/local/.zfs/snapshot/20090816
> > $ echo i >> o
> > bash: o: Read-only file system
> > $ uname -a
> > FreeBSD X 8.0-RC1 FreeBSD 8.0-RC1 #71: Sun Oct 18 07:05:25 BST 2009
> > root at X:/usr/obj/usr/src/sys/me  amd64
> >
> >
>


ah whops it does panic my box 8(

its fine on opensolaris though so is a bsdism

$ pwd
/vms/windows_update/.zfs/
snapshot/zfs-auto-snap:hourly-2009-07-29-21:00/tmc-vmx
$ ls -l Windows\ XP\ Professional-s004
-rwxrwx--- 1 cscott staff 2145976320 2009-06-19 11:23 Windows XP
Professional-s004
$ echo oo >> Windows\ XP\ Professional-s004
bash: Windows XP Professional-s004: Read-only file system
 $ uname -a
SunOS cscott-desktop2 5.11 snv_111b i86pc i386 i86pc Solaris