not working kernel 4.4.0-34

[raxip]

@elmystico
I tried your git branch on ubuntu 16.04 with kernel 4.4.0-34 and it's broken. It compiled and installed, and allowed me to create a cache, but shortly thereafter it crashed. The filesystem became unresponsive, and it wouldn't let me delete the cache either.

I had to hard boot the server, and enhanceio could not load the cache on boot up.

[ 97.465486] enhanceio: module verification failed: signature and/or required key missing - tainting kernel
[ 97.704849] enhanceio: md_load: Cache superblock mismatch detected. (current: 3, ondisk: 0)
[ 97.704853] enhanceio: md_load: Can't enable cache . Either superblock version is invalid or cache has been deleted
[ 97.759607] enhanceio: Cache metadata loaded from disk with 0 valid 0 dirty blocks
[ 97.759618] enhanceio: Cache creation failed: Failed to reload cache.
[ 126.599099] enhanceio: Cache creation failed: get_device for cache device failed.
[ 126.685175] enhanceio: Cache creation failed: get_device for cache device failed.
[ 126.728092] enhanceio: Cache creation failed: get_device for cache device failed.
[ 126.767133] enhanceio: Cache creation failed: get_device for cache device failed.
[ 126.865539] enhanceio: Cache creation failed: get_device for cache device failed.

How do I either fix or completely remove enhanceio?

[elmystico]

@raxip
Hey, I haven't touched the kernel code at all, so I can only guess looking at your log. Maybe it's not working with 4.4? I was testing it with 4.6 and 4.7 kernels.
BUT- does your system use systemd as init? If it doesn't- the problem may be that systems starts the main drive and do writes BEFORE ssd cache is enabled for that drive. Things get out-of-sync and that's how everything gets corrupted.
My code is meant to be used with systemd, I haven't tested it without it (just with plain udev I mean).

If you want to disable just do
eio_cli delete -c

[raxip]

It's Ubuntu 16.04, so it is systemd. I removed the kernel modules. It looks like Enhanceio is basically dead with no maintainers. Time for bcache I suppose.

[elmystico]

@raxip
Yep, I know...
bcache needs different disk format, I didn't wanted that, so here I am- with enchanceio
I'll stick to it as long as I can do it with reasonable effort.
The best solution would be caching mechanism put directly into btrfs. This would literally change the world. Some people request this feature on official btrfs page... will it ever happen? Not a clue.