[PATCH] md: count corrected read errors per drive

Store this total in superblock (As appropriate), and make it available to
userspace via sysfs.

Signed-off-by: Neil Brown <neilb@suse.de>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index fd43fd2cad2f..a3eadf8e1701 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -222,6 +222,17 @@ Each directory contains:
                          of being recoverred to
         This list make grow in future.
 
+      errors
+        An approximate count of read errors that have been detected on
+        this device but have not caused the device to be evicted from
+        the array (either because they were corrected or because they
+        happened while the array was read-only).  When using version-1
+        metadata, this value persists across restarts of the array.
+
+        This value can be written while assembling an array thus
+        providing an ongoing count for arrays with metadata managed by
+        userspace.
+
 
 An active md device will also contain and entry for each active device
 in the array.  These are named