On 29/11/11 14:31, Kent Overstreet wrote:

quoted

I need to use this :
for i in /dev/sd? /dev/md* ; do [ -n "`/sbin/probe-bcache $i`" ]&&
echo $i>  /sys/fs/bcache/register_quiet ; done

Now, it does not actually need the test in there, however that stops
it spewing "write error: Invalid argument" onto the console when you
echo a device that does not have a bcache superblock.

It does NOT like you accidentally trying to register a device twice :

Eesh. That's annoying.

I suppose really the bcache symlink in the /sys/block/bcacheN directory
is incorrect - without that stacking _ought_ to work and I'm not sure
it's possible to reliably detect stacking anyways.

I'm not sure that stacking is the issue. I simply did

echo /dev/md10 > /sys/fs/bcache/register
echo /dev/md10 > /sys/fs/bcache/register

at that point it all came crashing down. I'd have thought simply 
detecting that a particular device was already registered would solve 
the problem.

Very annoying though - that symlink is very handy. Argh.

hm. maybe I could check the make_request_fn to detect stacking and
prevent it that way...

No other issues, I take it?

Well, I had intended to run some tests with it stacked on top of md, but 
as I pointed out in the last oops in my prior mail, every time I try and 
attach the cache set to /dev/md10 the machine panics, so I've not really 
progressed to actually trying things out. I figured re-running the tests 
I'd already run with it stacked on a single drive was pretty pointless.

Regards,
Brad