[ 13/75] md/bitmap: prevent bitmap_daemon_work running while initialising bitmap

From: Greg KH
Date: Thu Apr 19 2012 - 17:05:40 EST

3.3-stable review patch. If anyone has any objections, please let me know.


From: NeilBrown <neilb@xxxxxxx>

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
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@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1819,7 +1819,9 @@ int bitmap_load(struct mddev *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;

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