This should be more suitable to post in bug report. But I have no idea which package should be reported to. So better post here to, at least let others know the issue if they faced.
This is a reoccured issue "Upgrade Issue Debian 6, NFS/SMB" http://forums.debian.net/viewtopic.php?f=10&t=74916
This issue did not occur in Debian 7 and Debian 8.
Configuration:
SAMBA server: QNAP (OPLOCKS = true)
SAMBA client: Debian 9 (No cifs-utils / smbclient etc was used, just mount to SAMBA server with command "mount -t cifs ...")
Description:
Mounting SAMBA client to SAMBA server, then copy a huge file from SAMBA client to SAMBA server. After some time (~12GB) will get disk access error from SAMBA client.
Workaround:
Disable OPLOCKS in SAMBA server.
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