md-ensure-bitmap_writeback_daemon-handles-shutdown-properly.patch

From: NeilBrown <neilb@cse.unsw.edu.au>

mddev->bitmap gets clearred before the writeback daemon is stopped.  So the
write_back daemon needs to be careful not to dereference the 'bitmap' if it is
NULL.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 drivers/md/bitmap.c |    3 +++
 1 files changed, 3 insertions(+)

diff -puN drivers/md/bitmap.c~md-ensure-bitmap_writeback_daemon-handles-shutdown-properly drivers/md/bitmap.c
--- devel/drivers/md/bitmap.c~md-ensure-bitmap_writeback_daemon-handles-shutdown-properly	2005-08-29 23:44:34.000000000 -0700
+++ devel-akpm/drivers/md/bitmap.c	2005-08-29 23:44:34.000000000 -0700
@@ -1156,6 +1156,9 @@ static void bitmap_writeback_daemon(mdde
 		err = -EINTR;
 		goto out;
 	}
+	if (bitmap == NULL)
+		/* about to be stopped. */
+		return;
 
 	PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
 	/* wait on bitmap page writebacks */
_