Consider the case where a VD is deleted and the targetID of that VD is
assigned to a newly created VD. If the sequence of deletion/addition of VD
happens very quickly there is a possibility that second event (VD add)
occurs even before the driver processes the first event (VD delete).  As
event processing is done in deferred context the device list remains the
same (but targetID is re-used) so driver will not learn the VD
deletion/additon. I/Os meant for the older VD will be directed to new VD
which may lead to data corruption.

Make driver detect the deleted VD as soon as possible based on the RaidMap
update and block further I/O to that device.

Link: https://lore.kernel.org/r/20210528131307.25683-4-chandrakanth.patil@broadcom.comReported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NKashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: NChandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>