Re: ext4fs error "ext4_mb_generate_buddy:741:group 16, 8160 clusters in bitmap, 4064 in gd" (with repro)

On Thu, Aug 16, 2012 at 04:28:07PM +0200, Lukáš Czerner wrote:

After a little bit of tracing with the systemtap and blktrace ext4
does not seem to be doing anything wrong and yet we get part of the
block bitmap trimmed. This lead me to the scsi_debug driver itself
and indeed it seems that we have off-by-one bug there in the
unamp_region() which is causing the problem.

Thanks for finding this --- I was getting scared that ext4 users were
losing data in production.  It's good to know it was just a bug in the
scsi_debug driver.

						- Ted