releases/3.0.29/md-bitmap-prevent-bitmap_daemon_work-running-while-initialising-bitmap.patch

From afbaa90b80b1ec66e5137cc3824746bfdf559b18 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Thu, 12 Apr 2012 16:05:06 +1000
Subject: md/bitmap: prevent bitmap_daemon_work running while initialising bitmap

From: NeilBrown <neilb@suse.de>

commit afbaa90b80b1ec66e5137cc3824746bfdf559b18 upstream.

If a bitmap is added while the array is active, it is possible
for bitmap_daemon_work to run while the bitmap is being
initialised.
This is particularly a problem if bitmap_daemon_work sees
bitmap->filemap as non-NULL before it has been filled in properly.
So hold bitmap_info.mutex while filling in ->filemap
to prevent problems.

This patch is suitable for any -stable kernel, though it might not
apply cleanly before about 3.1.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/bitmap.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1897,7 +1897,9 @@ int bitmap_load(mddev_t *mddev)
 			 * re-add of a missing device */
 			start = mddev->recovery_cp;
 
+		mutex_lock(&mddev->bitmap_info.mutex);
 		err = bitmap_init_from_disk(bitmap, start);
+		mutex_unlock(&mddev->bitmap_info.mutex);
 	}
 	if (err)
 		goto out;