Re: Wrong DIF guard tag on ext2 write

From: Martin K. Petersen
Date: Tue Jun 01 2010 - 09:52:23 EST


>>>>> "James" == James Bottomley <James.Bottomley@xxxxxxx> writes:

James> Would it be too much work in the fs to mark the page dirty before
James> you begin altering it (and again after you finish, just in case
James> some cleaner noticed and initiated a write)? Or some other flag
James> that indicates page under modification? All the process
James> controlling the writeout (which is pretty high up in the stack)
James> needs to know is if we triggered the check error by altering the
James> page while it was in flight.

James> I agree that a block based retry would close all the holes ... it
James> just doesn't look elegant to me that the fs will already be
James> repeating the I/O if it changed the page and so will block.

I experimented with this approach a while back. However, I quickly got
into a situation where frequently updated blocks never made it to disk
because the page was constantly being updated. And all writes failed
with a guard tag error.

--
Martin K. Petersen Oracle Linux Engineering
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