[dm-devel] [PATCH 2/2] md/raid0: Do not bypass blocking queue entered for raid0 bios

Guilherme G. Piccoli gpiccoli at canonical.com
Mon May 6 18:48:01 UTC 2019

On 06/05/2019 13:50, Song Liu wrote:
> [...] 
> IIUC, we need this for all raid types. Is it possible to fix that in md.c so
> all types get the fix?
> Thanks,
> Song

Hi Song, thanks again for reviewing my code and provide input, much

I understand this could in theory affects all the RAID levels, but in
practice I don't think it'll happen. RAID0 is the only "blind" mode of
RAID, in the sense it's the only one that doesn't care at all with
failures. In fact, this was the origin of my other thread [0], regarding
the change of raid0's behavior in error cases..because it currently does
not care with members being removed and rely only in filesystem failures
(after submitting many BIOs to the removed device).

That said, in this change I've only took care of raid0, since in my
understanding the other levels won't submit BIOs to dead devices; we can
experiment that to see if it's true.

But I'd be happy to change all other levels also if you think it's
appropriate (or a simple generic change to md.c if it is enough). Do you
think we could go ahead with this change, and further improve that (to
cover all raid cases if necessary)?



[0] https://marc.info/?l=linux-raid&m=155562509905735

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