linux-kernel - Re: [PATCH] NFS: Fix mode bits and nlink count for v4 referral dirs

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Date:   Wed, 14 Oct 2020 18:17:10 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     "ashishsangwan2@...il.com" <ashishsangwan2@...il.com>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "anna.schumaker@...app.com" <anna.schumaker@...app.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] NFS: Fix mode bits and nlink count for v4 referral dirs

On Tue, 2020-10-06 at 08:14 -0700, Ashish Sangwan wrote:
> Request for mode bits and nlink count in the nfs4_get_referral call
> and if server returns them use them instead of hard coded values.
> 
> CC: stable@...r.kernel.org
> Signed-off-by: Ashish Sangwan <ashishsangwan2@...il.com>
> ---
>  fs/nfs/nfs4proc.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 6e95c85fe395..efec05c5f535 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -266,7 +266,9 @@ const u32 nfs4_fs_locations_bitmap[3] = {
>  	| FATTR4_WORD0_FSID
>  	| FATTR4_WORD0_FILEID
>  	| FATTR4_WORD0_FS_LOCATIONS,
> -	FATTR4_WORD1_OWNER
> +	FATTR4_WORD1_MODE
> +	| FATTR4_WORD1_NUMLINKS
> +	| FATTR4_WORD1_OWNER
>  	| FATTR4_WORD1_OWNER_GROUP
>  	| FATTR4_WORD1_RAWDEV
>  	| FATTR4_WORD1_SPACE_USED
> @@ -7594,16 +7596,28 @@ nfs4_listxattr_nfs4_user(struct inode *inode,
> char *list, size_t list_len)
>   */
>  static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr)
>  {
> +	bool fix_mode = true, fix_nlink = true;
> +
>  	if (!(((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) ||
>  	       (fattr->valid & NFS_ATTR_FATTR_FILEID)) &&
>  	      (fattr->valid & NFS_ATTR_FATTR_FSID) &&
>  	      (fattr->valid & NFS_ATTR_FATTR_V4_LOCATIONS)))
>  		return;
>  
> +	if (fattr->valid & NFS_ATTR_FATTR_MODE)
> +		fix_mode = false;
> +	if (fattr->valid & NFS_ATTR_FATTR_NLINK)
> +		fix_nlink = false;
>  	fattr->valid |= NFS_ATTR_FATTR_TYPE | NFS_ATTR_FATTR_MODE |
>  		NFS_ATTR_FATTR_NLINK | NFS_ATTR_FATTR_V4_REFERRAL;
> -	fattr->mode = S_IFDIR | S_IRUGO | S_IXUGO;
> -	fattr->nlink = 2;
> +
> +	if (fix_mode)
> +		fattr->mode = S_IFDIR | S_IRUGO | S_IXUGO;
> +	else
> +		fattr->mode |= S_IFDIR;
> +
> +	if (fix_nlink)
> +		fattr->nlink = 2;
>  }
>  
>  static int _nfs4_proc_fs_locations(struct rpc_clnt *client, struct
> inode *dir,

NACK to this patch. The whole point is that if the server has a
referral, then it is not going to give us any attributes other than the
ones we're already asking for because it may not even have a real
directory. The client is required to fake up an inode, hence the
existing code.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@...merspace.com