tree c36b108b47272d31cbe906cb4267829c02e9c121
parent 884162df2aadd7414bef4935e1a54976fd4e3988
author NeilBrown <neilb@suse.de> 1353978880 +1100
committer NeilBrown <neilb@suse.de> 1353978880 +1100

md/raid1{,0}: fix deadlock in bitmap_unplug.

If the raid1 or raid10 unplug function gets called
from a make_request function (which is very possible) when
there are bios on the current->bio_list list, then it will not
be able to successfully call bitmap_unplug() and it could
need to submit more bios and wait for them to complete.
But they won't complete while current->bio_list is non-empty.

So detect that case and handle the unplugging off to another thread
just like we already do when called from within the scheduler.

RAID1 version of bug was introduced in 3.6, so that part of fix is
suitable for 3.6.y.  RAID10 part won't apply.

Cc: stable@vger.kernel.org
Reported-by: Torsten Kaiser <just.for.lkml@googlemail.com>
Reported-by: Peter Maloney <peter.maloney@brockmann-consult.de>
Signed-off-by: NeilBrown <neilb@suse.de>