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Bug#898165: marked as forwarded (linux-image-3.16.0-6-amd64: can't mount NFS shares via nfs referrals)

Your message dated Thu, 17 May 2018 09:53:33 +0200
with message-id <[🔎] 19d4d696-3abc-42cd-28fb-86a24b572ddd@uni-mainz.de>
has caused the   report #898165,
regarding linux-image-3.16.0-6-amd64: can't mount NFS shares via nfs referrals
to be marked as having been forwarded to the upstream software
author(s) <linux-nfs@vger.kernel.org>

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-- 
898165: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=898165
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Hi everyone,

there might be a regression coming from this patch:
Since it got included in 3.16.54, our clients running a recent 3.16
kernel (like from Debian jessie-security) did not follow NFS 4.1
referrals (issued by nfs-ganesha) anymore.
I have built that exact Debian kernel package with just this patch
reversed and it worked again, so I got pretty confident that this patch
is at least strongly related to the problem.
Pradeep also confirmed the problem happening in 3.16.54 but not in 3.16.51.
Interestingly, this does *not* happen with 4.9 kernels, although the
patch was part of 4.9.80...

I have attached a pcap file of a machine running 3.16.56-1+deb8u1 in
which I try to login as a user where my home directory is
/uni-mainz.de/homes/schlarbm (with nfsrefer.zdv.uni-mainz.de:/ on
/uni-mainz.de) which is then referred to
fs02.uni-mainz.de:/vol/ma17/homes/schlarbm but that referral is not
followed by the client.

Please let me know if you need additional information to reproduce or
have suggestions on what we could try.

Best regards,
Moritz

On 05.11.2017 21:45, Chuck Lever wrote:
> Before traversing a referral and performing a mount, the mounted-on
> directory looks strange:
> 
> dr-xr-xr-x. 2 4294967294 4294967294 0 Dec 31  1969 dir.0
> 
> nfs4_get_referral is wiping out any cached attributes with what was
> returned via GETATTR(fs_locations), but the bit mask for that
> operation does not request any file attributes.
> 
> Retrieve owner and timestamp information so that the memcpy in
> nfs4_get_referral fills in more attributes.
> 
> Changes since v1:
> - Don't request attributes that the client unconditionally replaces
> - Request only MOUNTED_ON_FILEID or FILEID attribute, not both
> - encode_fs_locations() doesn't use the third bitmask word
> 
> Fixes: 6b97fd3da1ea ("NFSv4: Follow a referral")
> Suggested-by: Pradeep Thomas <pradeepthomas@gmail.com>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> Cc: stable@vger.kernel.org
> ---
>  fs/nfs/nfs4proc.c |   18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> I could send this as an incremental, but that just seems to piss
> off distributors, who will just squash them all together anyway.
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 6c61e2b..2662879 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -254,15 +254,12 @@ static int nfs4_map_errors(int err)
>  };
>  
>  const u32 nfs4_fs_locations_bitmap[3] = {
> -	FATTR4_WORD0_TYPE
> -	| FATTR4_WORD0_CHANGE
> +	FATTR4_WORD0_CHANGE
>  	| FATTR4_WORD0_SIZE
>  	| FATTR4_WORD0_FSID
>  	| FATTR4_WORD0_FILEID
>  	| FATTR4_WORD0_FS_LOCATIONS,
> -	FATTR4_WORD1_MODE
> -	| FATTR4_WORD1_NUMLINKS
> -	| FATTR4_WORD1_OWNER
> +	FATTR4_WORD1_OWNER
>  	| FATTR4_WORD1_OWNER_GROUP
>  	| FATTR4_WORD1_RAWDEV
>  	| FATTR4_WORD1_SPACE_USED
> @@ -6763,9 +6760,7 @@ static int _nfs4_proc_fs_locations(struct rpc_clnt *client, struct inode *dir,
>  				   struct page *page)
>  {
>  	struct nfs_server *server = NFS_SERVER(dir);
> -	u32 bitmask[3] = {
> -		[0] = FATTR4_WORD0_FSID | FATTR4_WORD0_FS_LOCATIONS,
> -	};
> +	u32 bitmask[3];
>  	struct nfs4_fs_locations_arg args = {
>  		.dir_fh = NFS_FH(dir),
>  		.name = name,
> @@ -6784,12 +6779,15 @@ static int _nfs4_proc_fs_locations(struct rpc_clnt *client, struct inode *dir,
>  
>  	dprintk("%s: start\n", __func__);
>  
> +	bitmask[0] = nfs4_fattr_bitmap[0] | FATTR4_WORD0_FS_LOCATIONS;
> +	bitmask[1] = nfs4_fattr_bitmap[1];
> +
>  	/* Ask for the fileid of the absent filesystem if mounted_on_fileid
>  	 * is not supported */
>  	if (NFS_SERVER(dir)->attr_bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID)
> -		bitmask[1] |= FATTR4_WORD1_MOUNTED_ON_FILEID;
> +		bitmask[0] &= ~FATTR4_WORD0_FILEID;
>  	else
> -		bitmask[0] |= FATTR4_WORD0_FILEID;
> +		bitmask[1] &= ~FATTR4_WORD1_MOUNTED_ON_FILEID;
>  
>  	nfs_fattr_init(&fs_locations->fattr);
>  	fs_locations->server = server;
>

Attachment: nfs-referral-broken.pcap
Description: application/vnd.tcpdump.pcap

begin:vcard
fn:Moritz Schlarb
n:Schlarb;Moritz
org;quoted-printable;quoted-printable:Johannes Gutenberg-Universit=C3=A4t Mainz;Zentrum f=C3=BCr Datenverarbeitung
adr;dom:;;;Mainz
email;internet:schlarbm@uni-mainz.de
tel;work:+49 6131 39 29441
note;quoted-printable:OpenPGP Fingerprint: DF01 2247 BFC6=0D=0A=
	5501 AFF2 8445 0C24 B841 C7DD BAAF
version:2.1
end:vcard

Attachment: signature.asc
Description: OpenPGP digital signature


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