From: Neil Brown <neilb@notabene.brown>
Date: Fri, 27 Jun 2008 22:31:27 +0000 (+1000)
Subject: Don't try to make md arrays dirty if that is not meaningful.
X-Git-Tag: v2.6.27-rc1~957^2~49
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1a0fd497733bd029a7d5f2e5c69b1dff715b7792;p=karo-tx-linux.git

Don't try to make md arrays dirty if that is not meaningful.

Arrays personalities such as 'raid0' and 'linear' have no redundancy,
and so marking them as 'clean' or 'dirty' is not meaningful.
So always allow write requests without requiring a superblock update.

Such arrays types are detected by ->sync_request being NULL.  If it is
not possible to send a sync request we don't need a 'dirty' flag because
all a dirty flag does is trigger some sync_requests.

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

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 97852099defd..9e3ce432e37e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5536,6 +5536,8 @@ void md_allow_write(mddev_t *mddev)
 		return;
 	if (mddev->ro)
 		return;
+	if (!mddev->pers->sync_request)
+		return;
 
 	spin_lock_irq(&mddev->write_lock);
 	if (mddev->in_sync) {