md: add documentation for bad block log
Previous patch in the bad block series added new sysfs interfaces
([unacknowledged_]bad_blocks) for each rdev without documentation.
Add it.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/Documentation/md.txt b/Documentation/md.txt
index f0eee83..923a6bd 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -419,7 +419,6 @@
written, it will be rejected.
recovery_start
-
When the device is not 'in_sync', this records the number of
sectors from the start of the device which are known to be
correct. This is normally zero, but during a recovery
@@ -435,6 +434,20 @@
Setting this to 'none' is equivalent to setting 'in_sync'.
Setting to any other value also clears the 'in_sync' flag.
+ bad_blocks
+ This gives the list of all known bad blocks in the form of
+ start address and length (in sectors respectively). If output
+ is too big to fit in a page, it will be truncated. Writing
+ "sector length" to this file adds new acknowledged (i.e.
+ recorded to disk safely) bad blocks.
+
+ unacknowledged_bad_blocks
+ This gives the list of known-but-not-yet-saved-to-disk bad
+ blocks in the same form of 'bad_blocks'. If output is too big
+ to fit in a page, it will be truncated. Writing to this file
+ adds bad blocks without acknowledging them. This is largely
+ for testing.
+
An active md device will also contain and entry for each active device