Re: do_mount_autofs_direct: failed to create mount directory ...

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On 09.04.21 02:50, Ian Kent wrote:
On Thu, 2021-04-08 at 19:50 +0200, Frank Thommen wrote:
Dear all,

I have problems "submounting" a share when using direct mounts.
the following automounter tables:

/-  /etc/auto.groups

/groups/group1/int        server:/export/group1
/groups/group1/int/svc/a  server2:/export/service_a
/groups/group2/int        server2:/export/group2
/groups/group3/int        server:/export/group3
[... ca. 100 entries here ...]

/groups/group1/int/svc/a is not mounted and I get the error message
"do_mount_autofs_direct: failed to create mount directory
/groups/group1/int/svc/a" on any host which doesn not have root
permissions (no_root_squash) on server:/export/group1 (which is on
of all clients).

autofs won't (shouldn't) create directories in remote file systems
to perform mounts, it requires they are already present.

The directory "svc/a" has been created on server:/export/group1, so
there is no need to recreate it.

I am sure autofs /did/ recreate it.  But I will doublecheck that.

Which you have done.
Presumably the permissions are ok?

Are special permissions required?

I haven't looked at this case for a very long time but I'm pretty
sure nesting isn't allowed in direct mount maps (with any map type
really). I'm also pretty sure I don't test for nesting in direct
mount maps (quite difficult to do) and fail the trigger mount.

If you need to nest mounts your supposed to use offsets in the
mount entry (with both direct or indirect maps).

For example:
/groups/group1/int  /       server:/export/group1
                     /svc/a  server2:/export/service_a

where the "/" for the root offset is optional but may help with
map readability.

I wasn't aware that multi-maps were also possible with direct maps. However we had major issues with updating such configurations, as an update of the "nested" part requires an autofs re/start/, while otherwise a re/load/ suffices. We must avoid autofs restarts in our environment at all costs, as they can lead to short interruptions in the accessibility of shares, which is a problem in a cluster environment where theses accesses happen all the time. See also our long thread "Changes in indirect multi-maps don't become effective w/o autofs restart" in 2019 ;-)

If I may digress with a short syntactical question: Is the \ at the end of the line in multi-maps not required? This would explain strange effects that we had when we indented some of the keys in some direct maps (to enhance readability)

I've not seen problem reports like this from direct mount map users
so I'm pretty sure nesting isn't normally used so I'm not sure it
will work properly.

However the testing I use does include pass/fail tests for direct
mount map entries with offsets so it should work.

There could unfixed problems with the version of autofs you are using
which we would need to look at separately.

There are additional subdirectories in /groups/group1/int/svc/ which
directly reside on server:/export/group1.  Only "a" need to be
from a second location.

I think this should work fine using an offset as described above.

Those other directories are present in the mount that contains the
offset trigger so it should appear the same as you were hoping the
original map entry would except that by using an offset the expire
should now work.

Can this be solved with direct mounts?  How?  We would prefer to use
direct mounts, as this has shown to create the least problems when
dynamically changing the mount tables (no automounter restart is
required).  However I would not have a problem to use some indirect
mount mechanism for /groups/group1/int/svc/a as long as the main
/groups/groupN/int can stay in a direct mount table.

But you do need to do a reload for the direct mount triggers to
be updated, right?

yes a reload is required, but a reload doesn't disrupt access to NFS shares while a restart can/does (which is a major issue in our cluster environment, see above)



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