Hi Martin,
A bug was opened against the Ubuntu kernel[0]. After a kernel bisect,
it was found that reverting the following commit resolved this bug:
commit 66c28f97120e8a621afd5aa7a31c4b85c547d33d
Author: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Date: Thu Jun 6 22:15:55 2013 -0400
[SCSI] sd: Update WRITE SAME heuristics
The regression was introduced as of v3.11-rc1, but it also made it's way
into the stable trees.
I see that you are the author of this patch, so I wanted to run this by
you. I was thinking of requesting a revert for v3.12, but I wanted to
get your feedback first.
http://git.kernel.org/cgit/linux/kernel/git/jejb/scsi.git/commit/?id=735e39e680256a13e7be3492acfb4d9721287a42