Re: [PATCH v3 00/11] Add RDMA support to the pNFS file+flexfiles data channels

["Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>]

I have added some debug info Ind got this:

decode_getdeviceinfo: layout type 4
decode_getdeviceinfo: layout size 64
decode_getdeviceinfo: layout notification bitmap size 1094994757

So it looks like that xdr_read_pages set xdr pointer to a wrong position
and next read, which is bitmap size

5857         pdev->mincount = be32_to_cpup(p);
5858         dprintk("%s: layout size %u\n", __func__, pdev->mincount);
5859         if (xdr_read_pages(xdr, pdev->mincount) != pdev->mincount)
5860                 return -EIO;
5861 
5862         /* Parse notification bitmap, verifying that it is zero. */
5863         p = xdr_inline_decode(xdr, 4);
5864         if (unlikely(!p))
5865                 return -EIO;
5866         len = be32_to_cpup(p);
5867         dprintk("%s: layout notification bitmap size %u\n", __func__, len);
5868         if (len) {
5869                 uint32_t i;


Tigran.


----- Original Message -----
> From: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
> To: "trondmy" <trondmy@hammerspace.com>
> Cc: "linux-nfs" <linux-nfs@vger.kernel.org>, "Anna Schumaker" <anna.schumaker@netapp.com>
> Sent: Tuesday, 17 November, 2020 15:50:57
> Subject: Re: [PATCH v3 00/11] Add RDMA support to the pNFS file+flexfiles data channels

> Here is the result:
> 
> 
> $ git bisect bad
> c567552612ece787b178e3b147b5854ad422a836 is the first bad commit
> commit c567552612ece787b178e3b147b5854ad422a836
> Author: Anna Schumaker <Anna.Schumaker@Netapp.com>
> Date:   Wed May 28 13:41:22 2014 -0400
> 
>    NFS: Add READ_PLUS data segment support
>    
>    This patch adds client support for decoding a single NFS4_CONTENT_DATA
>    segment returned by the server. This is the simplest implementation
>    possible, since it does not account for any hole segments in the reply.
>    
>    Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> 
> fs/nfs/nfs42xdr.c         | 141 ++++++++++++++++++++++++++++++++++++++++++++++
> fs/nfs/nfs4client.c       |   2 +
> fs/nfs/nfs4proc.c         |  43 +++++++++++++-
> fs/nfs/nfs4xdr.c          |   1 +
> include/linux/nfs4.h      |   2 +-
> include/linux/nfs_fs_sb.h |   1 +
> include/linux/nfs_xdr.h   |   2 +-
> 7 files changed, 187 insertions(+), 5 deletions(-)
> 
> 
> Regards,
>   Tigran.
> 
> 
> 
> ----- Original Message -----
>> From: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
>> To: "trondmy" <trondmy@hammerspace.com>
>> Cc: "linux-nfs" <linux-nfs@vger.kernel.org>
>> Sent: Monday, 16 November, 2020 21:55:50
>> Subject: Re: [PATCH v3 00/11] Add RDMA support to the pNFS file+flexfiles data
>> channels
> 
>> Hi Trond,
>> 
>> I am afraid, that the fix didn't work. I bisecting it....
>> 
>> 
>> Tigran.
>> 
>> 
>> ----- Original Message -----
>>> From: "trondmy" <trondmy@hammerspace.com>
>>> To: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
>>> Cc: "linux-nfs" <linux-nfs@vger.kernel.org>
>>> Sent: Saturday, 14 November, 2020 15:29:01
>>> Subject: Re: [PATCH v3 00/11] Add RDMA support to the pNFS file+flexfiles data
>>> channels
>> 
>>> On Sat, 2020-11-14 at 00:46 +0100, Mkrtchyan, Tigran wrote:
>>>> 
>>>> 
>>>> ----- Original Message -----
>>>> > From: "trondmy" <trondmy@hammerspace.com>
>>>> > To: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
>>>> > Cc: "linux-nfs" <linux-nfs@vger.kernel.org>
>>>> > Sent: Friday, 13 November, 2020 23:45:00
>>>> > Subject: Re: [PATCH v3 00/11] Add RDMA support to the pNFS
>>>> > file+flexfiles data channels
>>>> 
>>>> > On Fri, 2020-11-13 at 22:30 +0100, Mkrtchyan, Tigran wrote:
>>>> > > 
>>>> > > After more testing, it looks like that client doesn't like
>>>> > > notification bitmap:
>>>> > > 
>>>> > > 
>>>> > > [31576.789492] --> _nfs4_proc_getdeviceinfo
>>>> > > [31576.789503] --> nfs41_call_sync_prepare data->seq_server
>>>> > > 000000001d17c43e
>>>> > > [31576.789507] --> nfs4_alloc_slot used_slots=0000
>>>> > > highest_used=4294967295 max_slots=16
>>>> > > [31576.789510] <-- nfs4_alloc_slot used_slots=0001 highest_used=0
>>>> > > slotid=0
>>>> > > [31576.789527] encode_sequence:
>>>> > > sessionid=2910695007:150995712:0:16777216 seqid=92462 slotid=0
>>>> > > max_slotid=0 cache_this=0
>>>> > > [31576.789991] decode_getdeviceinfo: unsupported notification
>>>> > 
>>>> > According to this, you appear to be returning a deviceinfo bitmap
>>>> > with
>>>> > at least one non-zero entry that is not in the first 32-bit word.
>>>> > We
>>>> > only ask for notifications for NOTIFY_DEVICEID4_CHANGE and
>>>> > NOTIFY_DEVICEID4_DELETE, so we only expect bitmap[0] to have non-
>>>> > zero
>>>> > entries.
>>>> 
>>>> 
>>>> according to packet capture only bitmap[0] has non zero bits set.
>>>> This is the reply of compound starting from nfs staus code, tag
>>>> length and so on.
>>>> 
>>>> 
>>>> 0000   00 00 00 00 00 00 00 00 00 00 00 02 00 00 00 35
>>>> 0010   00 00 00 00 5f ae 7d ad 00 03 00 09 00 00 00 00
>>>> 0020   00 00 00 01 00 00 00 4c 00 00 00 00 00 00 00 0f
>>>> 0030   00 00 00 0f 00 00 00 00 00 00 00 2f 00 00 00 00
>>>> 0040   00 00 00 04 00 00 00 40 00 00 00 01 00 00 00 03
>>>> 0050   74 63 70 00 00 00 00 16 31 33 31 2e 31 36 39 2e
>>>> 0060   31 39 31 2e 31 34 33 2e 31 32 35 2e 34 39 00 00
>>>> 0070   00 00 00 01 00 00 00 04 00 00 00 01 00 10 00 00
>>>> 0080   00 10 00 00 00 00 00 01 00 00 00 02 00 00 00 06
>>>> 0090   00 00 00 00
>>>> 
>>>> 
>>>> the last 12 bytes : bitmap size, bitmap[0], bitmap[1]
>>>> 
>>>> 
>>>> This part of code in the didn't change since 2010, and I
>>>> have no issues to use 5.8 kernel. I am pretty sure, that
>>>> tests with 5.9 did pass as expected. I will try to bisec it.
>>> 
>>> I don't think I've introduced this bug. I did not touch anything in the
>>> getdeviceinfo proc or XDR code.
>>> Does the following patch help?
>>> 
>>> 8<-------------------------------------------------------
>>> From e92b2d4e39e91d379ec1147115820ab5dfe4c89a Mon Sep 17 00:00:00 2001
>>> From: Trond Myklebust <trond.myklebust@hammerspace.com>
>>> Date: Fri, 13 Nov 2020 21:42:16 -0500
>>> Subject: [PATCH] NFSv4: Fix the alignment of page data in the getdeviceinfo
>>> reply
>>> 
>>> We can fit the device_addr4 opaque data padding in the pages.
>>> 
>>> Fixes: cf500bac8fd4 ("SUNRPC: Introduce rpc_prepare_reply_pages()")
>>> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
>>> ---
>>> fs/nfs/nfs4xdr.c | 14 ++++++++++----
>>> 1 file changed, 10 insertions(+), 4 deletions(-)
>>> 
>>> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
>>> index c6dbfcae7517..c8714381d511 100644
>>> --- a/fs/nfs/nfs4xdr.c
>>> +++ b/fs/nfs/nfs4xdr.c
>>> @@ -3009,15 +3009,19 @@ static void nfs4_xdr_enc_getdeviceinfo(struct rpc_rqst
>>> *req,
>>> 	struct compound_hdr hdr = {
>>> 		.minorversion = nfs4_xdr_minorversion(&args->seq_args),
>>> 	};
>>> +	uint32_t replen;
>>> 
>>> 	encode_compound_hdr(xdr, req, &hdr);
>>> 	encode_sequence(xdr, &args->seq_args, &hdr);
>>> +
>>> +	replen = hdr.replen + op_decode_hdr_maxsz;
>>> +
>>> 	encode_getdeviceinfo(xdr, args, &hdr);
>>> 
>>> -	/* set up reply kvec. Subtract notification bitmap max size (2)
>>> -	 * so that notification bitmap is put in xdr_buf tail */
>>> +	/* set up reply kvec. device_addr4 opaque data is read into the
>>> +	 * pages */
>>> 	rpc_prepare_reply_pages(req, args->pdev->pages, args->pdev->pgbase,
>>> -				args->pdev->pglen, hdr.replen - 2);
>>> +				args->pdev->pglen, replen + 2);
>>> 	encode_nops(&hdr);
>>> }
>>> 
>>> @@ -5848,7 +5852,9 @@ static int decode_getdeviceinfo(struct xdr_stream *xdr,
>>> 	 * and places the remaining xdr data in xdr_buf->tail
>>> 	 */
>>> 	pdev->mincount = be32_to_cpup(p);
>>> -	if (xdr_read_pages(xdr, pdev->mincount) != pdev->mincount)
>>> +	/* Calculate padding */
>>> +	len = xdr_align_size(pdev->mincount);
>>> +	if (xdr_read_pages(xdr, len) != len)
>>> 		return -EIO;
>>> 
>>> 	/* Parse notification bitmap, verifying that it is zero. */
>>> --
>>> 2.28.0
>>> 
>>> 
>>> 
>>> --
>>> Trond Myklebust
>>> Linux NFS client maintainer, Hammerspace
> > > trond.myklebust@hammerspace.com