1 files changed, 23 insertions, 6 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index f0eee83ff78a..fc94770f44ab 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -360,18 +360,20 @@ Each directory contains:
         A file recording the current state of the device in the array
         which can be a comma separated list of
               faulty   - device has been kicked from active use due to
-                         a detected fault
+                         a detected fault or it has unacknowledged bad
+                         blocks
               in_sync  - device is a fully in-sync member of the array
               writemostly - device will only be subject to read
                          requests if there are no other options.
                          This applies only to raid1 arrays.
-              blocked  - device has failed, metadata is "external",
-                         and the failure hasn't been acknowledged yet.
+              blocked  - device has failed, and the failure hasn't been
+                         acknowledged yet by the metadata handler.
                          Writes that would write to this device if
                          it were not faulty are blocked.
               spare    - device is working, but not a full member.
                          This includes spares that are in the process
                          of being recovered to
+              write_error - device has ever seen a write error.
         This list may grow in future.
         This can be written to.
         Writing "faulty"  simulates a failure on the device.
@@ -379,9 +381,11 @@ Each directory contains:
         Writing "writemostly" sets the writemostly flag.
         Writing "-writemostly" clears the writemostly flag.
         Writing "blocked" sets the "blocked" flag.
-        Writing "-blocked" clears the "blocked" flag and allows writes
-                to complete.
+        Writing "-blocked" clears the "blocked" flags and allows writes
+                to complete and possibly simulates an error.
         Writing "in_sync" sets the in_sync flag.
+        Writing "write_error" sets writeerrorseen flag.
+        Writing "-write_error" clears writeerrorseen flag.
 
         This file responds to select/poll. Any change to 'faulty'
         or 'blocked' causes an event.
@@ -419,7 +423,6 @@ Each directory contains:
         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 +438,20 @@ Each directory contains:
         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