Re: LVM + Raid5 + make_request

From: Jan Kara (
Date: Thu Jun 01 2000 - 05:41:29 EST


> I'm trying to get the LVM driver working over a raid5
> under 2.4.0-test1-ac2. There seems to be a problem with the
> LVM and raid5 make_request functions.
> "What we have here is a failure to comunnicate."
> LVM remaps the blocks by changing bh->b_rsector.
> Raid5 then ignores that field and looks at bh->b_blocknr.
> As a result, LVM LVs on a raid5 are broken. Seems this
> could be fixed one of three ways:
> 1) Have LVM change bh->b_blocknr.
> 2) Have Raid5 use bh->b_rsector instead of computing
> the sector from bh->b_blocknr.
  This is the right thing. I think there was some mail
in L-K from Andrea when he was rewriting ll_rw_blk that
this is the way drivers should go.


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