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Date:      Fri, 24 Nov 2023 07:18:08 -0600
From:      Mike Karels <mike@karels.net>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        Alexander Leidinger <Alexander@leidinger.net>, Rick Macklem <rmacklem@freebsd.org>, src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org
Subject:   Re: git: f5f277728ade - main - nfsd: Fix NFS access to .zfs/snapshot snapshots
Message-ID:  <F4EB20B7-5AB8-4448-84BB-462BC7C37398@karels.net>
In-Reply-To: <ZWCe8k_lxWSpDA1L@kib.kiev.ua>
References:  <202311231525.3ANFPBo6039293@gitrepo.freebsd.org> <987d4593d50b9cbffb9b6443d3825499@Leidinger.net> <ZWCe8k_lxWSpDA1L@kib.kiev.ua>

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On 24 Nov 2023, at 7:02, Konstantin Belousov wrote:

> On Fri, Nov 24, 2023 at 08:50:22AM +0100, Alexander Leidinger wrote:
>> Am 2023-11-23 16:25, schrieb Rick Macklem:
>>> The branch main has been updated by rmacklem:
>>>
>>> URL: https://cgit.FreeBSD.org/src/commit/?id=3Df5f277728adec4c5b3e840=
a1fb16bd16f8cc956d
>>>
>>> commit f5f277728adec4c5b3e840a1fb16bd16f8cc956d
>>> Author:     Rick Macklem <rmacklem@FreeBSD.org>
>>> AuthorDate: 2023-11-23 15:23:33 +0000
>>> Commit:     Rick Macklem <rmacklem@FreeBSD.org>
>>> CommitDate: 2023-11-23 15:23:33 +0000
>>>
>>>     nfsd: Fix NFS access to .zfs/snapshot snapshots
>>>
>>>     When a process attempts to access a snapshot under
>>>     /<dataset>/.zfs/snapshot, the snapshot is automounted.
>>>     However, without this patch, the automount does not
>>>     set mnt_exjail, which results in the snapshot not being
>>>     accessible over NFS.
>>>
>>>     This patch defines a new function called vfs_exjail_clone()
>>>     which sets mnt_exjail from another mount point and
>>>     then uses that function to set mnt_exjail in the snapshot
>>>     automount.  A separate patch that is currently a pull request
>>>     for OpenZFS, calls this function to fix the problem.
>>
>> May the same/similar fix like for ZFS be needed / useful for nullfs mo=
unted
>> stuff?
>>
>> I have a ZFS dataset which is mounted via nullfs into a jail. This
>> nullfs-mount is then exported via samba. In samba I have the shadow-co=
py
>> stuff enabled, but it doesn't work, as the jails can't access the snap=
shot.
>
> Jails cannot access snapshots because, as I understand, snapshots
> are mounts. Nullfs does not provide an option to recursively bypass
> into mounts. The patch you responded to does not automatically mounts
> snapshots on clients, it only allows them to mount if wanted.

It works for me, with main and this change, or 13.2 without a patch.
I don't know the mechanics, but it doesn't use nullfs, and the snapshot
does not show up as a separate filesystem with the mount command.

		Mike

> You might try to set up something with autofs, no idea if it could be m=
ade
> to work usefully.



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