fs: add iput_if_not_last() helper

Add a helper that drops an inode reference only if the caller does not
hold the last one.  Returns true if the reference was dropped, false
otherwise.

This is useful for filesystems that need to release inode references
in contexts where triggering final iput (and thus eviction) would be
unsafe due to lock ordering constraints.  The caller can check the
return value and defer the final iput to a safe context.

Unlike iput_not_last() which BUG_ON's if called with the last ref,
this variant is designed to be called speculatively.

Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner (Amutable) <brauner@kernel.org>
Tested-by: syzbot@syzkaller.appspotmail.com
Link: https://patch.msgid.link/20260710030851.2791589-2-yun.zhou@windriver.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

0 files changed, 0 insertions, 0 deletions