afs: Add some comments explaining 'needvalid'

Add some comments to try and help explain the meaning of the
'needvalid' parameter to GetDSlot, added in
1a672914ab050811c99b6307c657630ab9b5c8ee.

Change-Id: I4f1c704fa131df07e671f46b1b7575fbf607fce4
Reviewed-on: http://gerrit.openafs.org/7429
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementix.org>

diff --git a/src/afs/afs_dcache.c b/src/afs/afs_dcache.c
index 846033b..e3bae9b 100644 (file)
--- a/src/afs/afs_dcache.c
+++ b/src/afs/afs_dcache.c
@@ -2599,6 +2599,7 @@ afs_WriteThroughDSlots(void)
  *
  * Parameters:
  *     aslot : Dcache slot to look at.
+ *      needvalid : Whether the specified slot should already exist
  *
  * Environment:
  *     Must be called with afs_xdcache write-locked.
@@ -2626,6 +2627,9 @@ afs_MemGetDSlot(afs_int32 aslot, int needvalid)
        return tdc;
     }
 
+    /* if 'needvalid' is true, the slot must already exist and be populated
+     * somewhere. for memcache, the only place that dcache entries exist is
+     * in memory, so if we did not find it above, something is very wrong. */
     osi_Assert(!needvalid);
 
     if (!afs_freeDSList)
@@ -2687,6 +2691,7 @@ unsigned int last_error = 0, lasterrtime = 0;
  *
  * Parameters:
  *     aslot : Dcache slot to look at.
+ *      needvalid : Whether the specified slot should already exist
  *
  * Environment:
  *     afs_xdcache lock write-locked.