md: notify userspace on 'write-pending' changes to array_state

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index d31aa6f33a6a..52f9865096c6 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5435,8 +5435,11 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
                         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);
 }