Date: Mon, 12 May 2008 10:40:05 GMT From: Jaakko Heinonen <jh@saunalahti.fi> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/122833: [snapshots] [patch] mountd fails on nmount() after UFS snapshot creation with mount Message-ID: <200805121040.m4CAe5d0034090@freefall.freebsd.org>
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The following reply was made to PR kern/122833; it has been noted by GNATS. From: Jaakko Heinonen <jh@saunalahti.fi> To: =?utf-8?B?R2HDq2w=?= Roualland <gael.roualland@dial.oleane.com> Cc: bug-followup@FreeBSD.org, leon.kos@lecad.fs.uni-lj.si, rodrigc@FreeBSD.org, Yar Tikhiy <yar@comp.chem.msu.su> Subject: Re: kern/122833: [snapshots] [patch] mountd fails on nmount() after UFS snapshot creation with mount Date: Mon, 12 May 2008 13:37:00 +0300 Hi, On 2008-05-11, Gaël Roualland wrote: > After looking a bit in mount and mksnap_ffs, this seems due to a > difference in the way the snapshot is created : mount calls nmount(2), > while mksnap_ffs only calls mount(2). This bug occurs because when doing a snapshot with nmount(2) call (with "snapshot" option) the "snapshot" option string persists for the mount point even after the nmount call. Later nmount(2) calls made by mountd(8) fail because the ffs code tries to create a snapshot due to "snapshot" option string presence. You can work around the problem without reboot by removing the option string with mount -o nosnapshot <mountpoint> The bug could be worked around in mountd code but IMO a proper fix is needed in kernel nmount code. There are also other ways to reproduce the bug: # mount -o snapshot /.snap/foo / # mount -u -o atime / mount: /dev/ad2s1a : Cross-device link # mount -o nosnapshot / # mount -u -o atime / # -- Jaakko
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