scsi: storvsc: Re-init stor_chns when a channel interrupt is re-assigned

For each storvsc_device, storvsc keeps track of the channel target CPUs
associated to the device (alloced_cpus) and it uses this information to
fill a "cache" (stor_chns) mapping CPU->channel according to a certain
heuristic.  Update the alloced_cpus mask and the stor_chns array when a
channel of the storvsc device is re-assigned to a different CPU.

Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by; Long Li <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
[ wei: fix a small issue reported by kbuild test robot <[email protected]> ]
Signed-off-by: Wei Liu <[email protected]>
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index b85d7580..cd64ab7b 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -773,6 +773,9 @@ struct vmbus_channel {
 	void (*onchannel_callback)(void *context);
 	void *channel_callback_context;
 
+	void (*change_target_cpu_callback)(struct vmbus_channel *channel,
+			u32 old, u32 new);
+
 	/*
 	 * Synchronize channel scheduling and channel removal; see the inline
 	 * comments in vmbus_chan_sched() and vmbus_reset_channel_cb().