[Bug 14498] New: Why is mount -a is not detecting an already mounted DFS share endpoint

[Bug 14498] New: Why is mount -a is not detecting an already mounted DFS share endpoint

[samba-bugs]

https://bugzilla.samba.org/show_bug.cgi?id=14498

            Bug ID: 14498
           Summary: Why is mount -a is not detecting an already mounted
                    DFS share endpoint
           Product: CifsVFS
           Version: 3.x
          Hardware: x64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: user space tools
          Assignee: jlayton@samba.org
          Reporter: Chris@craftypenguins.net
        QA Contact: cifs-qa@samba.org
  Target Milestone: ---

I am trying to figure out why mount -a is not detecting an already mounted DFS
share endpoint. It works as expected on mount.cifs version 5.5 but not 6.7

Distributor ID: Debian
Description:    Debian GNU/Linux 9.13 (stretch)
Release:        9.13
Codename:       stretch

Mount.cifs version 6.7. 

/etc/fstab 
//ctserver6/ops_apps    /mnt/ops_apps cifs  
defaults,credentials=/root/.smbcredentials,rw,users,_netdev,soft   0 0 
//ctserverbc/Public     /mnt/ctserverbc cifs   
defaults,credentials=/root/.smbcredentials,rw,users,_netdev,soft 0 0 
#//ctserver3/ops         /mnt/ops cifs             
defaults,credentials=/root/.smbcredentials,rw,users,_netdev,soft   0 0 
#//ctserver3/public      /mnt/public cifs        
defaults,credentials=/root/.smbcredentials,rw,users,_netdev,soft 0 0 
//ctdomain.local/DFS_OPS/OPS       /mnt/ops cifs       
vers=2.1,credentials=/root/.smbcredentials,rw,users,_netdev,soft   0 0 
//ctdomain.local/DFS_OPS/Public    /mnt/public cifs   
vers=2.1,credentials=/root/.smbcredentials,rw,users,_netdev,soft   0 0 

If I leave off the vers=2.1 option it will create a new mount process and
duplicate in /proc/mounts :
/mnt/ops_apps            : already mounted
/mnt/ctserverbc          : already mounted
mount.cifs kernel mount options:
ip=192.168.111.10,unc=\\ctdomain.local\DFS_OPS,soft,user=ctlinux,prefixpath=OPS,pass=********
/mnt/ops                 : successfully mounted
mount.cifs kernel mount options:
ip=192.168.111.20,unc=\\ctdomain.local\DFS_OPS,soft,user=ctlinux,prefixpath=Public,pass=********
/mnt/public              : successfully mounted

With vers=2.1 I get:

/mnt/ops_apps            : already mounted 
/mnt/ctserverbc          : already mounted 
mount.cifs kernel mount options:
ip=192.168.111.20,unc=\\ctdomain.local\DFS_OPS,vers=2.1,soft,user=ctlinux,prefixpath=OPS,pass=******** 
mount error(16): Device or resource busy Refer to the mount.cifs(8) manual page
(e.g. man mount.cifs) 
mount.cifs kernel mount options:
ip=192.168.111.20,unc=\\ctdomain.local\DFS_OPS,vers=2.1,soft,user=ctlinux,prefixpath=Public,pass=******** 
mount error(16): Device or resource busy Refer to the mount.cifs(8) manual page
(e.g. man mount.cifs) 

On 5.5 it will detect the DFS share is mounted already

-- 


Chris Pickett |
Linux Systems Engineer

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[Bug 14498] Why is mount -a is not detecting an already mounted DFS share endpoint

[samba-bugs]

https://bugzilla.samba.org/show_bug.cgi?id=14498

--- Comment #1 from Chris Pickett <Chris@craftypenguins.net> ---
The result is duplicate mount processes created for every mount -a attempted.
We had a cron that was calling mount -a every 5 min so we were building up
quite a few entries in /proc/mounts.

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[Bug 14498] Why is mount -a is not detecting an already mounted DFS share endpoint

[samba-bugs]

https://bugzilla.samba.org/show_bug.cgi?id=14498

--- Comment #2 from Steve French <sfrench@samba.org> ---
What is the kernel version on the two (the failing and working kernels)?

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[Bug 14498] Why is mount -a is not detecting an already mounted DFS share endpoint

[samba-bugs]

https://bugzilla.samba.org/show_bug.cgi?id=14498

--- Comment #3 from Chris Pickett <Chris@craftypenguins.net> ---
The kernel version is the same on both systems. They are LCX containers running
on Proxmox kernel version 4.15.18-30-pve. However, they are on separate
hypervisors.

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