[dm-devel] Question about dm target size

Josef Bacik jbacik at fb.com
Wed Nov 12 11:00:00 UTC 2014

On 11/12/2014 03:45 AM, Zdenek Kabelac wrote:
> Dne 12.11.2014 v 03:30 Josef Bacik napsal(a):
>> Sorry for top posting, my phone client doesn't do inline.
>> I'm splitting the disk in half, writing to alternating sides of the
>> disk and keeping track of where which block is so when the power fail
>> event occurs the subsequent reads come from the corresponding mirror
>> in the disk. The disk needs to appear to be size/2 for the mkfs to
>> know the correct size, but my target needs to be able to write up to
>> size.  I looked at thinp but it reflects the full size right? It's
>> just like a sparse find correct? My ->map function does the right
>> thing, doing the ->len trick makes it all work out right, but this is
>> really isolated testing. Thanks,
> Just a side note - maybe you would like to rather extend functionality
> of dm-flakey  target ?

I did that first but it ended up being really ugly.  With all the 
varying functionality in dm-flakey it ended up making the table format 
horrible and the code a spaghetti of if (test_bit()) crap everywhere. 


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