[linux-cifs-client] Cifs, loop, large files and umount results in CIFS VFS: No writable handles for inode - on both Ubuntu and Debian

[Thomas Kjaergaard]

Hi

//mounting
mount -t cifs -o credentials=/root/scripts/linkstation.cfg
//192.168.100.9/backup /mnt/linkstation

//setting up loop device
losetup /dev/loop0 /mnt/linkstation/driveimage

//mount the loop device in /mnt/backup
mount /dev/loop0 /mnt/backup

I can now write files to the mounted filesystem.

Then I unmount with:

//dismount
umount /mnt/backup

//remove loop
losetup -d /dev/loop0

//dismount
umount /mnt/linkstation

The problems:
-------
After the umount in dmesg and syslog I get:
CIFS VFS: No writable handles for inode
The amount of the errors depends on how much I have been writing to the loop
device.
A simple mount and unmount gives 2 lines with the errors, if I have copied
500MB to the device it's multiple pages with the error.

Remark, the "No writable handles for inode" errors does first appear in
syslog after umount.

Small files in the root and empty folders are gone next time I mount the
loop device.
-------


The file driveimage file is created before first use after cifs mount with:
dd if=/dev/zero of=/mnt/linkstation/driveimage bs=1M count=1 seek=5000
losetup /dev/loop0 /mnt/linkstation/driveimage
mkfs.ext3 /dev/loop0

I have tried with 5GB and the target is 350GB and eventually 1TB when we get
a bigger NAS.


I have tried from two different distros as client.

Debian running 2.6.25-2-686 and CIFS Version 1.52
Ubuntu running 2.6.24-19-server and CIFS Version 1.52

Using two different servers:

One being a Bufalo Linkstation, running Samba 3.0.21c according to:
"cat /proc/fs/cifs/DebugData" when the linkstation is mounted.

The other is the above mentioned Debian running Samba 3.0.30.


The goal is to use a NAS as storage for an encrypted filesystem which is
mounted when the backups needs to be updated.
mount -t cifs -o credentials=/root/scripts/linkstation.cfg
//192.168.100.9/backup /mnt/linkstation
mount -o loop,encryption=aes /mnt/linkstation/driveimage /mnt/backup -p0 <
/root/scripts/loop.cfg

The encryption does not seem to influence if the errors are there or not.
Is it the cifs or is it the loop device which is causing the problems?


Best Regards
Thomas Kjaergaard