ocfs2: cluster: avoid lock order inversion in o2hb_region_pin() from drop_item

o2hb_heartbeat_group_drop_item() is called from configfs rmdir with the
parent directory's inode_lock held.  It calls o2hb_region_pin() ->
o2nm_depend_item() -> configfs_depend_item(), which acquires the configfs
root inode_lock.  This creates a parent -> root inode_lock nesting that
could deadlock against paths taking root -> parent (e.g.  subsystem
unregistration).

Fix this by using configfs_depend_item_unlocked() when o2hb_region_pin()
is called from a configfs callback context.  This variant skips the root
inode_lock when caller and target are in the same subsystem, which is safe
because VFS already holds a lock preventing unregistration.

Add o2nm_depend_item_unlocked() wrapper and a from_callback parameter to
o2hb_region_pin() to select the appropriate variant.

Link: https://lore.kernel.org/20260722124933.430554-3-joseph.qi@linux.alibaba.com
Fixes: 58a3158a5d17 ("ocfs2/cluster: Pin/unpin o2hb regions")
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Heming Zhao <heming.zhao@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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions