md: add 'write_error' flag to component devices.

If a device has ever seen a write error, we will want to handle
known-bad-blocks differently.
So create an appropriate state flag and export it via sysfs.

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 7c3192c0a29a..fa4b607854ac 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -84,6 +84,9 @@ struct mdk_rdev_s
 #define Blocked         8               /* An error occurred on an externally
                                          * managed array, don't allow writes
                                          * until it is cleared */
+#define WriteErrorSeen  9               /* A write error has been seen on this
+                                         * device
+                                         */
         wait_queue_head_t blocked_wait;
 
         int desc_nr;                    /* descriptor index in the superblock */