Re: [PATCH v5 05/10] vfs: lookup_open(): use vfs_create_no_perm()

[Christian Brauner]

On Sun, Aug 23, 2026 at 06:07:01PM +0200, Jori Koolstra wrote:
> We can replace the code in the no create_error/negative dentry found
> from lookup case in lookup_open() with the vfs_create_no_perm() helper.
> 
> Reviewed-by: NeilBrown <neil@xxxxxxxxxx>
> Signed-off-by: Jori Koolstra <jkoolstra@xxxxxxxxx>
> ---
>  fs/namei.c | 20 +++++++-------------
>  1 file changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 55ba23f95c5b..3afae6e87825 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -4430,8 +4430,14 @@ static struct dentry *atomic_open(const struct path *path, struct dentry *dentry
>  		}
>  		dput(dentry);
>  		dentry = ERR_PTR(error);
> +	} else {
> +		if (file->f_mode & FMODE_CREATED)
> +			fsnotify_create(dir_inode, dentry);
> +		if (file->f_mode & FMODE_OPENED)
> +			fsnotify_open(file);

Note that this causes duplicate IN_CREATE/IN_OPEN as both atomic_open()
and dentry_create() now notify.

>  	}
>  
> +
>  	return dentry;
>  }
>  
> @@ -4581,22 +4587,10 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
>  		goto out_dput;
>  	}
>  
> -	error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE, &delegated_inode);
> -	if (error)
> -		goto out_dput;
> -
> -	error = dir_inode->i_op->create(idmap, dir_inode, dentry, mode);
> -	if (error)
> -		goto out_dput;
> +	error = vfs_create_no_perm(idmap, dentry, mode, &delegated_inode);

Afaict, this has a latent bug until later in the series. Right now
failing ->create/try_break_deleg() sets FMODE_CREATED on a negative
dentry. That causes a splat in any sticky directory. And some nastiness
with failing to break a delegation as well.

>  
>  	file->f_mode |= FMODE_CREATED;
>  out:
> -	if (!IS_ERR(dentry)) {
> -		if (file->f_mode & FMODE_CREATED)
> -			fsnotify_create(dir_inode, dentry);
> -		if (file->f_mode & FMODE_OPENED)
> -			fsnotify_open(file);
> -	}
>  	if ((open_flag & O_CREAT) || create_error)
>  		inode_unlock(dir_inode);
>  	else
> -- 
> 2.55.0
> 

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