dm flakey: Document "error_writes" feature

Commit 9d6675f18f54 ("dm flakey: introduce "error_writes" feature")
added the ability to dm flakey to error out writes in contrast to
silently dropping it with 'drop_writes'. Unfortunately this feature
is not currently documented and one has to be either familiar with the
source code of dm flakey or check out xfstests sources to know of
this parameter. So document it.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/device-mapper/dm-flakey.txt b/Documentation/device-mapper/dm-flakey.txt
index c43030718cef4a5a43bb75416cc273fcd0c68a89..9f0e247d0877393287d6b147dd601615a2e3a937 100644 (file)
--- a/Documentation/device-mapper/dm-flakey.txt
+++ b/Documentation/device-mapper/dm-flakey.txt
@@ -33,6 +33,10 @@ Optional feature parameters:
        All write I/O is silently ignored.
        Read I/O is handled correctly.
 
+  error_writes:
+       All write I/O is failed with an error signalled.
+       Read I/O is handled correctly.
+
   corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
        During <down interval>, replace <Nth_byte> of the data of
        each matching bio with <value>.