dm: add flakey target

This target is the same as the linear target except that it returns I/O
errors periodically.  It's been found useful in simulating failing
devices for testing purposes.

I needed a dm target to do some failure testing on btrfs's raid code, and
Mike pointed me at this.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 98d9ec85e0eb..8420129fc5ee 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -327,4 +327,10 @@ config DM_UEVENT
         ---help---
         Generate udev events for DM events.
 
+config DM_FLAKEY
+       tristate "Flakey target (EXPERIMENTAL)"
+       depends on BLK_DEV_DM && EXPERIMENTAL
+       ---help---
+         A target that intermittently fails I/O for debugging purposes.
+
 endif # MD