[PATCH] md: Allow rdev state to be set via sysfs

The md/dev-XXX/state file can now be written:

 "faulty" simulates an error on the device
 "remove" removes the device from the array (if it is not busy)

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 28 insertions, 1 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index df0b45515775..4cf5972821a9 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -302,6 +302,9 @@ Each directory contains:
                          This includes spares that are in the process
                          of being recoverred to
         This list make grow in future.
+        This can be written to.
+        Writing "faulty"  simulates a failure on the device.
+        Writing "remove" removes the device from the array.
 
       errors
         An approximate count of read errors that have been detected on
diff --git a/drivers/md/md.c b/drivers/md/md.c
index f6562ee4c6fc..4b74c77213c3 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1745,8 +1745,32 @@ state_show(mdk_rdev_t *rdev, char *page)
         return len+sprintf(page+len, "\n");
 }
 
+static ssize_t
+state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+        /* can write
+         *  faulty  - simulates and error
+         *  remove  - disconnects the device
+         */
+        int err = -EINVAL;
+        if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
+                md_error(rdev->mddev, rdev);
+                err = 0;
+        } else if (cmd_match(buf, "remove")) {
+                if (rdev->raid_disk >= 0)
+                        err = -EBUSY;
+                else {
+                        mddev_t *mddev = rdev->mddev;
+                        kick_rdev_from_array(rdev);
+                        md_update_sb(mddev);
+                        md_new_event(mddev);
+                        err = 0;
+                }
+        }
+        return err ? err : len;
+}
 static struct rdev_sysfs_entry
-rdev_state = __ATTR_RO(state);
+rdev_state = __ATTR(state, 0644, state_show, state_store);
 
 static ssize_t
 super_show(mdk_rdev_t *rdev, char *page)