Date: Fri, 28 Apr 2023 11:02:21 +0200 From: Gerrit =?UTF-8?B?S8O8aG4=?= <gerrit.kuehn@aei.mpg.de> To: freebsd-fs@freebsd.org Subject: Re: canmount=noauto not behaving as expected Message-ID: <20230428110221.3f620207@arc.aei.uni-hannover.de> In-Reply-To: <20230427155449.2b94bdb3@arc.aei.uni-hannover.de> References: <20230427152159.508f097c@arc.aei.uni-hannover.de> <20230427155449.2b94bdb3@arc.aei.uni-hannover.de>
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Am Thu, 27 Apr 2023 15:54:49 +0200
schrieb Gerrit K=C3=BChn <gerrit.kuehn@aei.mpg.de>:
> However, I still don't get any of the nested filesystems mounted on
> "zpool import", they all stay unmounted there. So canmount is (quite
> unexpectedly to me) treated differently for "zpool import" and "zfs
> mount -a".
More precisely:
---
root@crest:/etc # zfs get canmount data/syncoid/pt-vault
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault canmount on default
root@crest:/etc # zfs get canmount data/syncoid/pt-vault/home
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault/home canmount noauto local
root@crest:/etc # zfs get canmount data/syncoid/pt-vault/home/archives
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault/home/archives canmount on default
---
So canmount=3Dnoauto is just set for one filesystem "in the middle", not for
the one above, nor for the one below.
---
root@crest:/etc # zfs mount -a
root@crest:/etc # zfs get mounted data/syncoid/pt-vault
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault mounted yes -
root@crest:/etc # zfs get mounted data/syncoid/pt-vault/home
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault/home mounted no -
root@crest:/etc # zfs get mounted data/syncoid/pt-vault/home/archives
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault/home/archives mounted yes -
---
After a "zfs mount -a" only the filesystem that is explicitely set to
"noauto" will be left out, the ones below will still mount. I didn't
really expect this, but so be it.
However, what I find really strange now is that "zpool import" behaves
differently:
---
root@crest:/etc # zpool export data
root@crest:/etc # zpool import data
root@crest:/etc # zfs get mounted data/syncoid/pt-vault/home/archives
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault/home/archives mounted no -
root@crest:/etc # zfs get mounted data/syncoid/pt-vault/home
NAME PROPERTY VALUE SOURCE
data/syncoid/pt-vault/home mounted no -
---
Importing appears to stop right at the level where canmount=3Dnoauto is set
and does not consider the filesystems below. The zfsprops manpage doesn't
comment on this situation explicitely, but from this I would have expected
that import and mount are treated the same way:
---
When set to noauto, a dataset can only be mounted and unmounted
explicitly. The dataset is not mounted automatically when the
dataset is created or imported, nor is it mounted by the zfs mount
-a command or unmounted by the zfs unmount -a command.
---
Maybe the manpage could be improved here to mention this? The manpage for
zpool-import also doesn't mention which filesystems are mounted
automatically and which ones aren't (it just features the -N flag that
prevents any filesystems from being mounted).
cu
Gerrit
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