Re: [PATCH] ocfs2: fix deadlock in dio write orphan cleanup path

[Matthew Wilcox <willy@infradead.org>]

On Sat, Jun 20, 2026 at 01:38:02PM +0530, Deepanshu Kartikey wrote:
> PREEMPT_RT's rtmutex PI chain walker detected a lock dependency
> cycle in a single thread:
> 
>   ocfs2_file_write_iter()
>     inode_lock(file_inode)             [Lock A]
>       ocfs2_dio_end_io_write()
>         ocfs2_inode_lock()             [Lock B]
>           ocfs2_del_inode_from_orphan()
>             inode_lock(orphan_dir)     [Lock D] <- cycle detected!

This seems like a false positive.  You can't call write_iter() on
a directory, and orphan_dir is always a directory.

I would suggest that the easiest way to make this warning go away is to
replace inode_lock(orphan_dir) with inode_lock_nested(orphan_dir,
I_MUTEX_NONDIR2).  It's a bit quirky because, well, orphan2 is a
directory.  We could add a seventh lock class to
inode_i_mutex_lock_class, but that feels a bit excessive.