[pve-devel] [PATCH storage] cephfs: Exclude _netdev when mounting with fuse

[Thomas Lamprecht]

On 6/11/19 2:28 PM, Alwin Antreich wrote:
> Note: fuse3 (3.4.1) in buster supports _netdev
> 

It got "supported" (read, ignored) by FUSE's default mount helper
since quite a bit longer:
https://github.com/libfuse/libfuse/commit/b32c79b97079d2de63213bbeb12d3bf57e7e6643
(included since 2.5.0, released at start of 2006)

So not sure what you mean here. Further, while ceph-fuse uses it's own
mount helper, thus not falling back to above's FUSE default one, it
also ignores that flag since quite a bit:
https://github.com/ceph/ceph/commit/9ac264a856dc68090f9ecf0fb23319429490f829#diff-d4afd4fceb081fb97b3bc47aab999381

But, as we use ceph-fuse directly, and it is a bit lax regarding
argument parsing[0] this misses there completely, the ceph project
should probably adapt something like sshfs[1] did in response to
that..

[0]: https://github.com/ceph/ceph/blob/master/src/ceph_fuse.cc#L108
[1]: https://github.com/libfuse/sshfs/commit/608e7ab89c7f6c4362f8e9a07133adcd26aa63da

So where did you got that with FUSE 3.4.1 from, as I cannot find
anything related to that version and IMO it's clearly a ceph bug,
albeit one the probably can probably argue against, as it works in
the tool used for fstab and for general mount calls but not for
direct interaction with the "lower level" ceph-fuse tool.

The proposed fix by you is probably OK, but the info why it is an
issue and why it's OK to workaround like this is missing a bit,
I'll try to adapt the commit message respectively after a night
of sleep :)