On Thu, 26 Feb 2015, Mikulas Patocka wrote: > In the function snapshot_resume we perform exception store handover. If > there is another active snapshot target, the exception store is moved from > this target to the target that is being resume. > > The problem is that if there is some pending exception, it will point to > an incorrect exception store after that handover, causing crash in BUG in > dm-snap-persistent.c:get_exception - see bug 1177389. > > This bug can be triggered by repeatedly changing snapshot permissions with > "lvchange -p r" and "lvchange -p rw" while there are writes on the > associated origin device. > > To fix this bug, we must suspend the origin device when doing the > exception store handover to make sure that there is no pending exception. > > This patch: > - introdices _origin_hash that keeps track of dm_origin structures. > - introduces function __lookup_dm_origin, __insert_dm_origin and > __remove_dm_origin that manipulate the origin hash. > - modifies snapshot_resume so that it calls dm_internal_suspend_fast and > dm_internal_resume_fast on the origin device. > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> I forgot to add Cc: stable@xxxxxxxxxxxxxxx Note to people who backport it: When backporting to kernels 3.12-3.18, use dm_internal_suspend and dm_internal_resume instead of dm_internal_suspend_fast and dm_internal_resume_fast. When backporting to kernels older than 3.12, you need to pick functions dm_internal_suspend and dm_internal_resume from the patch fd2ed4d252701d3bbed4cd3e3d267ad469bb832a. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
