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Date: Wed, 5 Jun 2024 17:49:23 +0200
From: Jan Kara <jack@suse.cz>
To: Mateusz Guzik <mjguzik@gmail.com>
Cc: brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/3] vfs: shave a branch in getname_flags
Message-ID: <20240605154923.sec53hhjnzgowvws@quack3>
References: <20240604155257.109500-1-mjguzik@gmail.com>
 <20240604155257.109500-4-mjguzik@gmail.com>
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In-Reply-To: <20240604155257.109500-4-mjguzik@gmail.com>

On Tue 04-06-24 17:52:57, Mateusz Guzik wrote:
> Check for an error while copying and no path in one branch.
> 
> Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>

Looks good to me modulo the need for rechecking Christian already pointed
out. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>


								Honza

> ---
>  fs/namei.c | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 950ad6bdd9fe..f25dcb9077dd 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -148,9 +148,20 @@ getname_flags(const char __user *filename, int flags)
>  	result->name = kname;
>  
>  	len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
> -	if (unlikely(len < 0)) {
> -		__putname(result);
> -		return ERR_PTR(len);
> +	/*
> +	 * Handle both empty path and copy failure in one go.
> +	 */
> +	if (unlikely(len <= 0)) {
> +		if (unlikely(len < 0)) {
> +			__putname(result);
> +			return ERR_PTR(len);
> +		}
> +
> +		/* The empty path is special. */
> +		if (!(flags & LOOKUP_EMPTY)) {
> +			__putname(result);
> +			return ERR_PTR(-ENOENT);
> +		}
>  	}
>  
>  	/*
> @@ -188,14 +199,6 @@ getname_flags(const char __user *filename, int flags)
>  	}
>  
>  	atomic_set(&result->refcnt, 1);
> -	/* The empty path is special. */
> -	if (unlikely(!len)) {
> -		if (!(flags & LOOKUP_EMPTY)) {
> -			putname(result);
> -			return ERR_PTR(-ENOENT);
> -		}
> -	}
> -
>  	result->uptr = filename;
>  	result->aname = NULL;
>  	audit_getname(result);
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR