if you using NFSshare and work with grouppermissions they will be lost sporadically if NFS is under heavy load by coping files.
add a NFSshare, add for example 5 folders with grouppermissions like:
rwxrwx--- root docs /myshare
rwxrwx--- root video /myvideoshare
The user is member of the groups. Then copy about 8GB from one share to the other. Or copy files in the share in another folder. Then the permissions are gone. You can't enter, you can't read anymore.
Tested on different hardware on different situations, same with NFS3/4 with and without acl's.
And the problem is userspecific. If i copy some files and i get permission denied, then every other user has still the right permissions. After they copy some files too over the nfsshares they have the same problem.
This is working fine here with kernel 4.10.17-5 Ubuntukernel. I can't tested it on the fast with another version from 4.13. because using here ZFS.
Thanks a lot
Addendum: To fix this temporaly, you have to restart the NFSservice and remount on the client.
we can confirm this bug. Since we upgraded our file server kernel to 22.214.171.124.26 we've been seeing random permission denied errors on NFS too. Back to 126.96.36.199.44 and the problem is gone.
Please let us know if we can help debug.
Dr. Christian Herzog <email@example.com> support: +41 44 633 26 68
IT Services Group, HPT H 8 voice: +41 44 633 39 50
Department of Physics, ETH Zurich
8093 Zurich, Switzerland http://nic.phys.ethz.ch/
This sounds like the bug fixed by bdcf0a423ea1c40bbb40e7ee483b50fc8aa3d758 "kernel: make groups_sort calling a responsibility group_info allocators", though I'd assumed that was a long-standing bug, not a recent regression. Are you running rpc.mountd with -g/--manage-gids?
OK, I see, the regression was probably introduced by b7b2562f7252878e18de60c24f320052076f9de8 "kernel/groups.c: use sort library function", which first appeared in 4.13. Previously the function used to sort group lists was a no-op in the case of a list that was already sorted. (I wonder whether userspace was passing down already-sorted group lists?)
while I can't answer your questions, we'd be happy to run tests on our dev system.
Your options are probably:
- stay on a pre-4.13 kernel until you have a 4.15-based kernel, or
- turn off the -g/--manage-gids rpc.mountd option (I don't know where that's configured on Ubuntu), or
- apply the "make groups_sort calling..." patch to your kernel manually.
And if any of those work that'd probably be enough confirmation that the bug is what I think it is.
> turn off the -g/--manage-gids rpc.mountd option
I check this...
(In reply to bfields from comment #6)
> Your options are probably:
> - stay on a pre-4.13 kernel until you have a 4.15-based kernel, or
> - turn off the -g/--manage-gids rpc.mountd option (I don't know where that's
> configured on Ubuntu), or
> - apply the "make groups_sort calling..." patch to your kernel manually.
> And if any of those work that'd probably be enough confirmation that the bug
> is what I think it is.
4.15 will be fine? Waiting then is the easiest option, but we might give the other two a shot...
4.15 will be fine? Waiting too for this version, because didn't find out where i had to disable rpc.mountd. Strange.