linux-kernel - Re: [PATCH] VFS: filename_create(): fix incorrect intent.

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Message-ID: <20220330101408.2bbb47ee@suse.de>
Date:   Wed, 30 Mar 2022 10:14:08 +0200
From:   David Disseldorp <ddiss@...e.de>
To:     "NeilBrown" <neilb@...e.de>
Cc:     Al Viro <viro@...iv.linux.org.uk>, linux-nfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] VFS: filename_create(): fix incorrect intent.

Hi Neil,

I gave this a spin and was wondering why xfstests wouldn't start with
this change...

On Mon, 28 Mar 2022 11:56:48 +1100, NeilBrown wrote:
...
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 3f1829b3ab5b..3ffb42e56a8e 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3676,7 +3676,6 @@ static struct dentry *filename_create(int dfd, struct filename *name,
>  	int type;
>  	int err2;
>  	int error;
> -	bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
>  
>  	/*
>  	 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
> @@ -3698,9 +3697,11 @@ static struct dentry *filename_create(int dfd, struct filename *name,
>  	/* don't fail immediately if it's r/o, at least try to report other errors */
>  	err2 = mnt_want_write(path->mnt);
>  	/*
> -	 * Do the final lookup.
> +	 * Do the final lookup.  Request 'create' only if there is no trailing
> +	 * '/', or if directory is requested.
>  	 */
> -	lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;
> +	if (!last.name[last.len] || (lookup_flags & LOOKUP_DIRECTORY))
> +		lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;

This doesn't look right, as any LOOKUP_DIRECTORY flag gets dropped via
the prior "lookup_flags &= LOOKUP_REVAL;".

Cheers, David