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From: Amir Goldstein <amir73il@gmail.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: [RFC][PATCH] ovl_create_index(): vfs_mkdir() might succeed leaving dentry negative unhashed
Date: Sat, 12 May 2018 07:49:21 +0300	[thread overview]
Message-ID: <CAOQ4uxi7Dk=th3ZwBHpxY+yF45-0FKbEXqwRB8HeH_CBr0HAOQ@mail.gmail.com> (raw)
In-Reply-To: <20180512012557.GJ30522@ZenIV.linux.org.uk>

On Sat, May 12, 2018 at 4:25 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> [same story as with the previous two patches]
>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index 8bede0742619..cdd8f8816d2a 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -373,6 +373,22 @@ static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
>         if (err)
>                 goto out;
>
> +       if (unlikely(d_unhashed(temp))) {
> +               struct dentry *d = lookup_one_len(temp->d_name.name,
> +                                                 temp->d_parent,
> +                                                 temp->d_name.len);
> +               if (IS_ERR(d)) {
> +                       err = PTR_ERR(d);
> +                       goto out;
> +               }
> +               dput(temp);
> +               temp = d;
> +               if (d_is_negative(temp)) {
> +                       err = -EIO;
> +                       goto out;
> +               }
> +       }
> +

:-/ this pattern is too nasty to be open codes twice in ovl and
once in knfsd.
For ovl, we can hoist this into the ovl_do_mkdir() helper, but
what filesystems really need is vfs_mkdir_hashed(), then knfsd
can use it as well.

Thanks,
Amir.

  parent reply	other threads:[~2018-05-12  4:49 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-12  1:25 [RFC][PATCH] ovl_create_index(): vfs_mkdir() might succeed leaving dentry negative unhashed Al Viro
2018-05-12  1:29 ` [PATCH][RFC] ovl_create_real(): make it cope with vfs_mkdir() safely Al Viro
2018-05-12  5:13   ` Amir Goldstein
2018-05-12  8:55     ` Amir Goldstein
2018-05-12  4:49 ` Amir Goldstein [this message]
2018-05-13 22:50   ` [RFC][PATCH] ovl_create_index(): vfs_mkdir() might succeed leaving dentry negative unhashed Al Viro
2018-05-14 15:04 ` Miklos Szeredi
2018-05-14 15:39   ` Al Viro

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