md/raid10: Fix memory leak when raid10 reshape completes.

When a raid10 commences a resync/recovery/reshape it allocates
some buffer space.
When a resync/recovery completes the buffer space is freed.  But not
when the reshape completes.
This can result in a small memory leak.

There is a subtle side-effect of this bug.  When a RAID10 is reshaped
to a larger array (more devices), the reshape is immediately followed
by a "resync" of the new space.  This "resync" will use the buffer
space which was allocated for "reshape".  This can cause problems
including a "BUG" in the SCSI layer.  So this is suitable for -stable.

Cc: stable@vger.kernel.org (v3.5+)
Fixes: 3ea7daa5d7fde47cd41f4d56c2deb949114da9d6
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index d9073a10f2f2..a46124ecafc7 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2953,6 +2953,7 @@ static sector_t sync_request(struct mddev *mddev, sector_t sector_nr,
                  */
                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
                         end_reshape(conf);
+                        close_sync(conf);
                         return 0;
                 }