LinuxCIFS troubleshooting

Enabling Debugging

The CIFS code contains a number of debugging statements that can be enabled. To enable debugging, echo a non-zero value into /proc/fs/cifs/cifsFYI. For example:

# modprobe cifs
# echo 7 > /proc/fs/cifs/cifsFYI

To disable it:

# echo 0 > /proc/fs/cifs/cifsFYI

These messages end up in the kernel ring buffer. You can view them using dmesg.

# dmesg

syslog will generally also pick up much of it, but if the rate of messages is rather large, syslog tends to drop it. Getting the info straight out of the ring buffer is generally preferred since that's lossless.

This debugging however can be rather chatty and have a significant impact on performance. It's often best to use this with easily reproducible problems. That is:

• turn on debugging
• reproduce the issue
• turn off debugging