Date: Wed, 16 Apr 2008 21:34:56 GMT From: Leon Kos <leon.kos@lecad.fs.uni-lj.si> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/122833: mountd fails on nmount() after UFS snapshot creation with mount Message-ID: <200804162134.m3GLYuAO052842@www.freebsd.org> Resent-Message-ID: <200804162140.m3GLe0SR016250@freefall.freebsd.org>
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>Number: 122833
>Category: kern
>Synopsis: mountd fails on nmount() after UFS snapshot creation with mount
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Apr 16 21:40:00 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator: Leon Kos
>Release: RELENG_7
>Organization:
University of Ljubljana
>Environment:
FreeBSD cad.lecad.uni-lj.si 7.0-STABLE FreeBSD 7.0-STABLE #22: Wed Apr 16 10:41:55 CEST 2008 leon@cad.lecad.uni-lj.si:/usr/obj/usr/src/sys/CAD i386
>Description:
After creating snapshot on filesystem mountd is unable to export under that tree.
Debugging /usr/src/usr.sbin/mountd/mountd.c shows that that it fails on nmount() when clearing exports list and also when creating it.
dmesg -a shows
Apr 16 18:37:06 cad mountd[1207]: can't delete exports for /usr: Cross-device link
Apr 16 18:37:06 cad mountd[1207]: can't export /usr/tmp
Apr 16 18:37:06 cad mountd[1207]: bad exports list line /usr /usr/tmp -network 192.168 -mask 255.255.0.0
Apr 16 18:49:52 cad mountd[1938]: can't delete exports for /usr: Cross-device link
Even tried mountd.c from trunk with no improvements.
When googling for "UFS snapshot weirdness" some users suggested that this is ipv6 issue. but from my experience it is not so.
>How-To-Repeat:
root@cad:~# showmount -e
Exports list on localhost:
/usr/tmp 192.168.0.0
/usr 192.168.0.0
/home/xlsvaje 192.168.5.0
/home 192.168.5.0
/tftpboot 192.168.0.0
root@cad:~# snapshot make /usr:daily
root@cad:~# showmount -e
Exports list on localhost:
/home/xlsvaje 192.168.5.0
/home 192.168.5.0
/tftpboot 192.168.0.0
>Fix:
Use command like:
root@cad:~# mksnap_ffs /usr /usr/.snap/daily.0
Do not use:
root@cad:~# mount -u -o snapshot /usr/.snap/daily.0 /usr
or
root@cad:~#snapshot make /usr:daily
When mountd fails to export only reboot helps.
Restarting mountd does not help.
Removing created snapshot does not help.
Attached patch is only the fix for freebsd-snapshot utility and not the solution.
Beware there could also be dangling /usr/sbin/snapshot
Patch attached with submission follows:
--- /usr/local/sbin/snapshot.orig 2008-04-16 19:42:15.000000000 +0200
+++ /usr/local/sbin/snapshot 2008-04-16 19:50:54.000000000 +0200
@@ -335,7 +335,7 @@
done
# create new snapshot
- system mount -u -o snapshot $fs_dir/.snap/$fs_tag.$fs_gen $fs_dir
+ system mksnap_ffs $fs_dir $fs_dir/.snap/$fs_tag.$fs_gen
fi
fi
>Release-Note:
>Audit-Trail:
>Unformatted:
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