linux-kernel - Re: [RFC PATCH v2 1/2] ovl: Define D_REAL_FILEDATA for d

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Date: Tue, 23 Apr 2024 08:54:25 +0300
From: Amir Goldstein <amir73il@...il.com>
To: Stefan Berger <stefanb@...ux.ibm.com>
Cc: linux-integrity@...r.kernel.org, linux-unionfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, zohar@...ux.ibm.com, roberto.sassu@...wei.com, 
	miklos@...redi.hu, brauner@...nel.org
Subject: Re: [RFC PATCH v2 1/2] ovl: Define D_REAL_FILEDATA for d_real to
 return dentry with data

On Mon, Apr 22, 2024 at 6:07 PM Stefan Berger <stefanb@...ux.ibm.com> wrote:
>
> Define D_REAL_FILEDATA which is to be used as a parameter for d_real()
> to return the dentry that is holding the file data, which is either the
> upper or the lower denry. The caller is expected to call d_real() again
> on the returned dentry to get to lower layers of a stacked filesystem,
> if available. This allows a caller to get all dentries involved in hold
> a file's data and iterate through the layers.
>

Did you miss my comments on v1?
https://lore.kernel.org/linux-unionfs/CAOQ4uxgNRYi-mYo=LZ5yiWch2zwDeTG2q9ZYD0ysEN6XaJkVhw@mail.gmail.com/

Did you not understand them?
Or did you just decide to ignore them?

Thanks,
Amir.

> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> ---
>  fs/overlayfs/super.c   | 6 ++++++
>  include/linux/dcache.h | 1 +
>  2 files changed, 7 insertions(+)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 06a231970cb5..f466ad89b005 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -36,6 +36,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type)
>         switch (type) {
>         case D_REAL_DATA:
>         case D_REAL_METADATA:
> +       case D_REAL_FILEDATA:
>                 break;
>         default:
>                 goto bug;
> @@ -47,6 +48,11 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type)
>         }
>
>         upper = ovl_dentry_upper(dentry);
> +       if (type == D_REAL_FILEDATA) {
> +               if (ovl_has_upperdata(d_inode(dentry)))
> +                       return upper;
> +               return ovl_dentry_lower(dentry);
> +       }
>         if (upper && (type == D_REAL_METADATA ||
>                       ovl_has_upperdata(d_inode(dentry))))
>                 return upper;
> diff --git a/include/linux/dcache.h b/include/linux/dcache.h
> index bf53e3894aae..e4e54fb2cf4e 100644
> --- a/include/linux/dcache.h
> +++ b/include/linux/dcache.h
> @@ -128,6 +128,7 @@ enum dentry_d_lock_class
>  enum d_real_type {
>         D_REAL_DATA,
>         D_REAL_METADATA,
> +       D_REAL_FILEDATA,
>  };
>
>  struct dentry_operations {
> --
> 2.43.0
>