[PATCH] md: Allow the write_mostly flag to be set via sysfs

It appears in /sys/mdX/md/dev-YYY/state
and can be set or cleared by writing 'writemostly' or '-writemostly'
respectively.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8603c0692eab..331b1bc95735 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1737,6 +1737,10 @@ state_show(mdk_rdev_t *rdev, char *page)
                 len += sprintf(page+len, "%sin_sync",sep);
                 sep = ",";
         }
+        if (test_bit(WriteMostly, &rdev->flags)) {
+                len += sprintf(page+len, "%swrite_mostly",sep);
+                sep = ",";
+        }
         if (!test_bit(Faulty, &rdev->flags) &&
             !test_bit(In_sync, &rdev->flags)) {
                 len += sprintf(page+len, "%sspare", sep);
@@ -1751,6 +1755,8 @@ state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
         /* can write
          *  faulty  - simulates and error
          *  remove  - disconnects the device
+         *  writemostly - sets write_mostly
+         *  -writemostly - clears write_mostly
          */
         int err = -EINVAL;
         if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
@@ -1766,6 +1772,12 @@ state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                         md_new_event(mddev);
                         err = 0;
                 }
+        } else if (cmd_match(buf, "writemostly")) {
+                set_bit(WriteMostly, &rdev->flags);
+                err = 0;
+        } else if (cmd_match(buf, "-writemostly")) {
+                clear_bit(WriteMostly, &rdev->flags);
+                err = 0;
         }
         return err ? err : len;
 }