Permission denied when chainbuilding packages with mock

[Julian Sikorski <belegdol@gmail.com>]

Hi,

I have originally posted this to samba list but we were not able to 
solve the issue:
https://lists.samba.org/archive/samba/2021-September/237428.html

In brief, I am getting seemingly random permission denied errors when 
chainbuilding packages with mock and pointing the result dir to a samba 
share:

$ mock --chain --localrepo=/mnt/openmediavault/kernel -r 
fedora-35-x86_64 goffice/goffice-0.10.50-2.fc35.src.rpm 
gnumeric/gnumeric-1.12.50-2.fc36.src.rpm
^^ this fails every time with: Error calculating checksum 
/mnt/openmediavault/kernel/results/fedora-35-x86_64/goffice-0.10.50-2.fc35/goffice-0.10.50-2.fc35.x86_64.rpm: 
(39, fsync failed: Permission denied)

$ mock --chain --localrepo=/mnt/openmediavault/kernel -r 
fedora-35-x86_64 goffice/goffice-0.10.50-1.fc35.src.rpm 
gnumeric/gnumeric-1.12.50-2.fc36.src.rpm
^^ this works when starting with goffice and goffice-devel packages 
removed from 
/mnt/openmediavault/kernel/results/fedora-35-x86_64/goffice-0.10.50-2.fc35. 
If goffice or goffice-devel packages are present in the resultdir, an 
error will appear:
Error calculating checksum 
/mnt/openmediavault/kernel/results/fedora-35-x86_64/goffice-0.10.50-2.fc35/goffice-devel-0.10.50-2.fc35.x86_64.rpm: 
(39, fsync failed: Permission denied)

So, summing up:
- same host
- same target dir
- same build target
- effectively the same package [1]
- different outcome

The target dir is mounted on the samba server as:
/dev/sda1 on /srv/dev-disk-by-label-omv type ext4 
(rw,noexec,relatime,discard,stripe=8191,jqfmt=vfsv0,usrjquota=aquota.user,grpjquota=aquota.group) 


And on the client as:
//odroidxu4.local/julian on /mnt/openmediavault type cifs 
(rw,relatime,vers=3.1.1,cache=strict,username=julas,uid=1000,noforceuid,gid=1000,noforcegid,addr=192.168.0.220,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,nobrl,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1,_netdev)

On the server one can see errors like:
[2021/11/07 15:45:48.710865, 10, pid=4069, effective(1000, 100), 
real(1000, 0), class=smb2] 
../source3/smbd/smb2_flush.c:138(smbd_smb2_flush_send)
   smbd_smb2_flush: 
kernel/results/fedora-35-x86_64/goffice-0.10.50-2.fc35/goffice-0.10.50-2.fc35.x86_64.rpm 
- fnum 3429228891
[2021/11/07 15:45:48.710935,  3, pid=4069, effective(1000, 100), 
real(1000, 0), class=smb2] 
../source3/smbd/smb2_server.c:3195(smbd_smb2_request_error_ex)
   smbd_smb2_request_error_ex: smbd_smb2_request_error_ex: idx[1] 
status[NT_STATUS_ACCESS_DENIED] || at ../source3/smbd/smb2_flush.c:82
[2021/11/07 15:45:48.711013, 10, pid=4069, effective(1000, 100), 
real(1000, 0), class=smb2] 
../source3/smbd/smb2_server.c:3086(smbd_smb2_request_done_ex)
   smbd_smb2_request_done_ex: idx[1] status[NT_STATUS_ACCESS_DENIED] 
body[8] dyn[yes:1] at ../source3/smbd/smb2_server.c:3243

but it is not really clear _why_ is the access being denied. Any ideas 
where to look? Thanks!

Best regards,
Julian