Config file won't open using legacy filp_open (btrfs)

[xtknight]

Some file systems may not support this legacy call. Replace it with vfs open call...

It could cause weird issues like all config values being 0, causing 802.11N not to work, etc...

[xtknight]

Thanks to @mkreisl for his help with this. The fix was simple after we figured out what was going on.

commit d25d8aa7b9cdc7fb7ff2a15f0c8bb993f4dad7cd
Author: andy <andy@europa>
Date:   Sun Mar 6 15:01:32 2016 -0500

    use vfs_read if no f_op->read

[xtknight]

There's also an f_op->write in here, I'll have to figure out what the use case for this is.