Re: ATA 4 KiB sector issues.

From: Martin K. Petersen
Date: Wed Mar 10 2010 - 00:08:43 EST


>>>>> "Karel" == Karel Zak <kzak@xxxxxxxxxx> writes:

[Cleaned up the CC: list from hell]

Karel> # cat /sys/block/md8/queue/{minimum,optimal}_io_size
Karel> 65536 65536

This one had me puzzled. We set min_io and opt_io correctly in raid5.c
depending on number of non-parity disks. And yet it turns into
something nonsensical after.

Turns out we overrun unsigned int calculating the lowest common multiple
in the stacking function. That's why we ended up with the wrong value.

I never noticed this because my userland topology regression test tool
uses unsigned long.

I'll get a patch off to Jens right away.

--
Martin K. Petersen Oracle Linux Engineering
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