X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fdrivers%2Fmd%2Fdm-bio-prison.h;fp=kernel%2Fdrivers%2Fmd%2Fdm-bio-prison.h;h=54352f009bfd5ad3cf011896536c4aa5baee18c6;hb=e09b41010ba33a20a87472ee821fa407a5b8da36;hp=74cf01144b1fc9c12777f669e1cf6e5e23422d44;hpb=f93b97fd65072de626c074dbe099a1fff05ce060;p=kvmfornfv.git

diff --git a/kernel/drivers/md/dm-bio-prison.h b/kernel/drivers/md/dm-bio-prison.h
index 74cf01144..54352f009 100644
--- a/kernel/drivers/md/dm-bio-prison.h
+++ b/kernel/drivers/md/dm-bio-prison.h
@@ -101,6 +101,19 @@ void dm_cell_visit_release(struct dm_bio_prison *prison,
 			   void (*visit_fn)(void *, struct dm_bio_prison_cell *),
 			   void *context, struct dm_bio_prison_cell *cell);
 
+/*
+ * Rather than always releasing the prisoners in a cell, the client may
+ * want to promote one of them to be the new holder.  There is a race here
+ * though between releasing an empty cell, and other threads adding new
+ * inmates.  So this function makes the decision with its lock held.
+ *
+ * This function can have two outcomes:
+ * i) An inmate is promoted to be the holder of the cell (return value of 0).
+ * ii) The cell has no inmate for promotion and is released (return value of 1).
+ */
+int dm_cell_promote_or_release(struct dm_bio_prison *prison,
+			       struct dm_bio_prison_cell *cell);
+
 /*----------------------------------------------------------------*/
 
 /*