Re: [PATCH v2 07/14] vfs: O_NONBLOCK|O_CREAT open shouldn't wait for directory delegation

[Jeff Layton <jlayton@kernel.org>]

On Sat, 2026-09-19 at 12:06 +1000, NeilBrown wrote:
> From: NeilBrown <neil@brown.name>
> 
> An open() of a regular file can block if there is an active lease on that
> file, but this can be prevented by opening with O_NONBLOCK.
> An open(O_CREAT) of a non-existent file can block if there is an active
> delegation on the parent directory but this CANNOT be prevented with
> O_NONBLOCK.
> 
> If nfsd is to use common VFS code for open/create it needs to be able to
> prevent this blocking.  It is conceivable that a user-space application
> might need this too.
> 
> So extend O_NONBLOCK protection to not block on a directory delegation
> when creating a file.
> 
> Fixes: 134796f43a5e ("vfs: break parent dir delegations in open(..., O_CREAT) codepath")
> Signed-off-by: NeilBrown <neil@brown.name>
> ---
>  fs/namei.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index a08f37aca3e1..b9fca38ad489 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -4554,7 +4554,12 @@ retry:
>  		goto out_dput;
>  	}
>  
> -	error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE, &delegated_inode);
> +	if (op->open_flag & O_NONBLOCK)
> +		error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE,
> +					NULL);
> +	else
> +		error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE,
> +					&delegated_inode);
>  	if (error)
>  		goto out_dput;
>  

That seems right. We don't want to block the opener while breaking the
directory lease.

Reviewed-by: Jeff Layton <jlayton@kernel.org>