md: be more careful setting MD_CHANGE_CLEAN

When MD_CHANGE_CLEAN is set we might block in md_write_start.
So we should only set it when fairly sure that something will clear
it.

There are two places where it is set so as to encourage a metadata
update to record the progress of resync/recovery.  This should only
be done if the internal metadata update mechanisms are in use, which
can be tested by by inspecting '->persistent'.

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

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 1742435..4518994 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1526,7 +1526,8 @@ void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
                   atomic_read(&bitmap->mddev->recovery_active) == 0);
 
        bitmap->mddev->curr_resync_completed = bitmap->mddev->curr_resync;
-       set_bit(MD_CHANGE_CLEAN, &bitmap->mddev->flags);
+       if (bitmap->mddev->persistent)
+               set_bit(MD_CHANGE_CLEAN, &bitmap->mddev->flags);
        sector &= ~((1ULL << CHUNK_BLOCK_SHIFT(bitmap)) - 1);
        s = 0;
        while (s < sector && s < bitmap->mddev->resync_max_sectors) {

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9007651..d636b0a 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6753,7 +6753,8 @@ void md_do_sync(mddev_t *mddev)
                                   atomic_read(&mddev->recovery_active) == 0);
                        mddev->curr_resync_completed =
                                mddev->curr_resync;
-                       set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+                       if (mddev->persistent)
+                               set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
                }