ocfs2: fix possible null-ptr-deref in ocfs2_set_buffer_uptodate

ocfs2: fix possible null-ptr-deref in ocfs2_set_buffer_uptodate

When doing cleanup, if flags without OCFS2_BH_READAHEAD, it may trigger
NULL pointer dereference in the following ocfs2_set_buffer_uptodate() if
bh is NULL.

Link: https://lkml.kernel.org/r/20240902023636.1843422-3-joseph.qi@linux.alibaba.com
Fixes: cf76c78595ca ("ocfs2: don't put and assigning null to bh allocated outside")
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reported-by: Heming Zhao <heming.zhao@suse.com>
Suggested-by: Heming Zhao <heming.zhao@suse.com>
Cc: <stable@vger.kernel.org>	[4.20+]
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mark@fasheh.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>