[PATCH 006 of 10] md: Notify userspace on 'write-pending' changes to array_state

[NeilBrown <neilb@suse.de>]

When an array enters write pending, 'array_state' changes, so we
must be sure to sysfs_notify.

Also, when waiting for user-space to acknowledge 'write-pending' by
marking the metadata as dirty, we don't want to wait for
MD_CHANGE_DEVS to be cleared as that might not happen.  So explicity
test for the bits that we are really interested in.

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
 ./drivers/md/md.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c	2008-05-19 11:02:35.000000000 +1000
+++ ./drivers/md/md.c	2008-05-19 11:03:43.000000000 +1000
@@ -5435,8 +5435,11 @@ void md_write_start(mddev_t *mddev, stru
 			md_wakeup_thread(mddev->thread);
 		}
 		spin_unlock_irq(&mddev->write_lock);
+		sysfs_notify(&mddev->kobj, NULL, "array_state");
 	}
-	wait_event(mddev->sb_wait, mddev->flags==0);
+	wait_event(mddev->sb_wait,
+		   !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
+		   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
 }
 
 void md_write_end(mddev_t *mddev)
@@ -5471,6 +5474,12 @@ void md_allow_write(mddev_t *mddev)
 			mddev->safemode = 1;
 		spin_unlock_irq(&mddev->write_lock);
 		md_update_sb(mddev, 0);
+
+		sysfs_notify(&mddev->kobj, NULL, "array_state");
+		/* wait for the dirty state to be recorded in the metadata */
+		wait_event(mddev->sb_wait,
+			   !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
+			   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
 	} else
 		spin_unlock_irq(&mddev->write_lock);
 }