Re: [SCSI][REGRESSION][BISECTED] Disk errors loop forever in 2.6.29

[Sitsofe Wheeler <sitsofe@yahoo.com>]

> From: James Bottomley <James.Bottomley@HansenPartnership.com>
>
> Can you try this patch ... it was something I meant to get into 2.6.29
> but forgot about.  The key problem that you seem to be hitting is that
> the requeue evades the timeout check.  Moving the timeout check to block
> should fix that.

Even by itself this patch works although the behaviour is now different
to that of 2.6.28.  Whereas in 2.6.28 it would timeout very quickly
(after about 1 or 2 seconds) it now times out after 30 seconds
(initially I hadn't realised that it would be so much longer). The
other difference is that the failure becomes cached - trying to reread
the same area using dd instantly fails from now on without any more disk
IO/kernel error messages until echo 1 > /proc/sys/vm/drop_caches is
issued. Before it would always go straight to the disk for the unread
section and the kernel spew would be repeated before the failure.

I guess if this is new intended behaviour then all is well - it's just
different and slower/faster :)

Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>