From 01318aaca0af3082f99b0eef937d55da783e7b2b Mon Sep 17 00:00:00 2001
From: Sami Tolvanen <samitolvanen@google.com>
Date: Thu, 26 Feb 2015 13:47:41 +0000
Subject: dm-verity: Add modes and emit uevent on corrupted blocks

Add a device specific mode to dm-verity for handling corrupted
blocks:

  DM_VERITY_MODE_EIO is the default behavior, where reading a
  corrupted block results in -EIO.

  DM_VERITY_MODE_LOGGING only logs corrupted blocks, but does
  not block the read.

  DM_VERITY_MODE_RESTART calls kernel_restart when a corrupted
  block is discovered.

Each mode sends a uevent to notify userspace of corruption and
allow further recovery actions.

Defaults to previous behavior, other modes can be enabled with
an optional parameter added to the verity table.

Change-Id: Ib72ae6ccb865594d28f3553bdcc5a40b1d7af390
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 Documentation/device-mapper/verity.txt | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

(limited to 'Documentation')

diff --git a/Documentation/device-mapper/verity.txt b/Documentation/device-mapper/verity.txt
index 988468153..2929f6b1c 100644
--- a/Documentation/device-mapper/verity.txt
+++ b/Documentation/device-mapper/verity.txt
@@ -10,7 +10,7 @@ Construction Parameters
     <version> <dev> <hash_dev>
     <data_block_size> <hash_block_size>
     <num_data_blocks> <hash_start_block>
-    <algorithm> <digest> <salt>
+    <algorithm> <digest> <salt> <mode>
 
 <version>
     This is the type of the on-disk hash format.
@@ -62,6 +62,16 @@ Construction Parameters
 <salt>
     The hexadecimal encoding of the salt value.
 
+<mode>
+    Optional. The mode of operation.
+
+    0 is the normal mode of operation where a corrupted block will result in an
+      I/O error.
+
+    1 is logging mode where corrupted blocks are logged and a uevent is sent to
+      notify user space.
+
+
 Theory of operation
 ===================
 
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