md: writing to sync_action should clear the read-auto state.

In some cases array are started in 'read-auto' state where in
nothing gets written to any device until the array is written
to.  The purpose of this is to make accidental auto-assembly
of the wrong arrays less of a risk, and to allow arrays to be
started to read suspend-to-disk images without actually changing
anything (as might happen if the array were dirty and a
resync seemed necessary).

Explicitly writing the 'sync_action' for a read-auto array currently
doesn't clear the read-auto state, so the sync action doesn't
happen, which can be confusing.

So allow any successful write to sync_action to clear any read-auto
state.

Reported-by: Alexander Kühn <alexander.kuehn@nagilum.de>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 7564c44..200d086 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4259,6 +4259,13 @@ action_store(struct mddev *mddev, const char *page, size_t len)
                set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
                set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
        }
+       if (mddev->ro == 2) {
+               /* A write to sync_action is enough to justify
+                * canceling read-auto mode
+                */
+               mddev->ro = 0;
+               md_wakeup_thread(mddev->sync_thread);
+       }
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        sysfs_notify_dirent_safe(mddev->sysfs_action);