Re: Does ceph_fill_inode() mishandle I_NEW?

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2025-03-13 at 20:47 +0000, David Howells wrote:
> slava@dubeyko.com wrote:
> 
> > What do you mean by mishandling? Do you imply that Ceph has to set up
> > the I_NEW somehow? Is it not VFS responsibility?
> 
> No - I mean that if I_NEW *isn't* set when the function is called,
> ceph_fill_inode() will go and partially reinitialise the inode.  Now, having
> reviewed the code in more depth and talked to Jeff Layton about it, I think
> that the non-I_NEW pass will only change pointers with some sort of locking
> and will release the old target - though it may overwrite some pointers with
> the same value without protection (i_fops for example).
> 
> That said, if it's possible for *two* processes to be going through that
> function without I_NEW set, you can get places where both of them will try
> freeing the old data and replacing it with new without any locking - but I
> don't know if that can happen.
> 

I don't think that can happen. An I_NEW inode hasn't been properly
hashed yet, so nothing should be able to find it until
unlock_new_inode() is called.

-- 
Jeff Layton <jlayton@kernel.org>