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diff --git a/Documentation/admin-guide/iostats.rst b/Documentation/admin-guide/iostats.rst
index 5d63b18bd6d1..4f0462af3ca7 100644
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+++ b/Documentation/admin-guide/iostats.rst
@@ -121,6 +121,15 @@ Field 15 -- # of milliseconds spent discarding
This is the total number of milliseconds spent by all discards (as
measured from __make_request() to end_that_request_last()).
+Field 16 -- # of flush requests completed
+ This is the total number of flush requests completed successfully.
+
+ Block layer combines flush requests and executes at most one at a time.
+ This counts flush requests executed by disk. Not tracked for partitions.
+
+Field 17 -- # of milliseconds spent flushing
+ This is the total number of milliseconds spent by all flush requests.
+
To avoid introducing performance bottlenecks, no locks are held while
modifying these counters. This implies that minor inaccuracies may be
introduced when changes collide, so (for instance) adding up all the