1 files changed, 6 insertions, 4 deletions

diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt
index 274752f8bdf9..719320b5ed3f 100644
--- a/Documentation/device-mapper/cache.txt
+++ b/Documentation/device-mapper/cache.txt
@@ -266,10 +266,12 @@ E.g.
 Invalidation is removing an entry from the cache without writing it
 back.  Cache blocks can be invalidated via the invalidate_cblocks
 message, which takes an arbitrary number of cblock ranges.  Each cblock
-must be expressed as a decimal value, in the future a variant message
-that takes cblock ranges expressed in hexidecimal may be needed to
-better support efficient invalidation of larger caches.  The cache must
-be in passthrough mode when invalidate_cblocks is used.
+range's end value is "one past the end", meaning 5-10 expresses a range
+of values from 5 to 9.  Each cblock must be expressed as a decimal
+value, in the future a variant message that takes cblock ranges
+expressed in hexidecimal may be needed to better support efficient
+invalidation of larger caches.  The cache must be in passthrough mode
+when invalidate_cblocks is used.
 
    invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]*