[PATCH 1/2] nfs: Only update callback sequnce id when CB_SEQUENCE success

[PATCH 1/2] nfs: Only update callback sequnce id when CB_SEQUENCE success

[Kinglong Mee]

When testing pnfs layout, nfsd got error NFS4ERR_SEQ_MISORDERED.
It is caused by nfs return NFS4ERR_DELAY before validate_seqid(),
don't update the sequnce id, but nfsd updates the sequnce id !!!

According to RFC5661 20.9.3,
" If CB_SEQUENCE returns an error, then the state of the slot
  (sequence ID, cached reply) MUST NOT change. "

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
---
 fs/nfs/callback_proc.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 197806f..7e9653a 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -327,10 +327,8 @@ validate_seqid(struct nfs4_slot_table *tbl, struct cb_sequenceargs * args)
 	dprintk("%s slot table seqid: %u\n", __func__, slot->seq_nr);
 
 	/* Normal */
-	if (likely(args->csa_sequenceid == slot->seq_nr + 1)) {
-		slot->seq_nr++;
+	if (likely(args->csa_sequenceid == slot->seq_nr + 1))
 		goto out_ok;
-	}
 
 	/* Replay */
 	if (args->csa_sequenceid == slot->seq_nr) {
@@ -418,6 +416,7 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 			      struct cb_process_state *cps)
 {
 	struct nfs4_slot_table *tbl;
+	struct nfs4_slot *slot;
 	struct nfs_client *clp;
 	int i;
 	__be32 status = htonl(NFS4ERR_BADSESSION);
@@ -429,7 +428,9 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 
 	if (!(clp->cl_session->flags & SESSION4_BACK_CHAN))
 		goto out;
+
 	tbl = &clp->cl_session->bc_slot_table;
+	slot = tbl->slots + args->csa_slotid;
 
 	spin_lock(&tbl->slot_tbl_lock);
 	/* state manager is resetting the session */
@@ -444,7 +445,7 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 		goto out;
 	}
 
-	status = validate_seqid(&clp->cl_session->bc_slot_table, args);
+	status = validate_seqid(tbl, args);
 	spin_unlock(&tbl->slot_tbl_lock);
 	if (status)
 		goto out;
@@ -468,6 +469,13 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 	res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
 	res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
 
+	/*
+	 * RFC5661 20.9.3
+	 * If CB_SEQUENCE returns an error, then the state of the slot
+	 * (sequence ID, cached reply) MUST NOT change.
+	 */
+	slot->seq_nr++;
+
 out:
 	cps->clp = clp; /* put in nfs4_callback_compound */
 	for (i = 0; i < args->csa_nrclists; i++)
-- 
2.4.2

Re: [PATCH 1/2] nfs: Only update callback sequnce id when CB_SEQUENCE success

[Kinglong Mee]

ping .... 

On 6/2/2015 6:58 PM, Kinglong Mee wrote:
> When testing pnfs layout, nfsd got error NFS4ERR_SEQ_MISORDERED.
> It is caused by nfs return NFS4ERR_DELAY before validate_seqid(),
> don't update the sequnce id, but nfsd updates the sequnce id !!!
> 
> According to RFC5661 20.9.3,
> " If CB_SEQUENCE returns an error, then the state of the slot
>   (sequence ID, cached reply) MUST NOT change. "
> 
> Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
> ---
>  fs/nfs/callback_proc.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
> index 197806f..7e9653a 100644
> --- a/fs/nfs/callback_proc.c
> +++ b/fs/nfs/callback_proc.c
> @@ -327,10 +327,8 @@ validate_seqid(struct nfs4_slot_table *tbl, struct cb_sequenceargs * args)
>  	dprintk("%s slot table seqid: %u\n", __func__, slot->seq_nr);
>  
>  	/* Normal */
> -	if (likely(args->csa_sequenceid == slot->seq_nr + 1)) {
> -		slot->seq_nr++;
> +	if (likely(args->csa_sequenceid == slot->seq_nr + 1))
>  		goto out_ok;
> -	}
>  
>  	/* Replay */
>  	if (args->csa_sequenceid == slot->seq_nr) {
> @@ -418,6 +416,7 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
>  			      struct cb_process_state *cps)
>  {
>  	struct nfs4_slot_table *tbl;
> +	struct nfs4_slot *slot;
>  	struct nfs_client *clp;
>  	int i;
>  	__be32 status = htonl(NFS4ERR_BADSESSION);
> @@ -429,7 +428,9 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
>  
>  	if (!(clp->cl_session->flags & SESSION4_BACK_CHAN))
>  		goto out;
> +
>  	tbl = &clp->cl_session->bc_slot_table;
> +	slot = tbl->slots + args->csa_slotid;
>  
>  	spin_lock(&tbl->slot_tbl_lock);
>  	/* state manager is resetting the session */
> @@ -444,7 +445,7 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
>  		goto out;
>  	}
>  
> -	status = validate_seqid(&clp->cl_session->bc_slot_table, args);
> +	status = validate_seqid(tbl, args);
>  	spin_unlock(&tbl->slot_tbl_lock);
>  	if (status)
>  		goto out;
> @@ -468,6 +469,13 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
>  	res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
>  	res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
>  
> +	/*
> +	 * RFC5661 20.9.3
> +	 * If CB_SEQUENCE returns an error, then the state of the slot
> +	 * (sequence ID, cached reply) MUST NOT change.
> +	 */
> +	slot->seq_nr++;
> +
>  out:
>  	cps->clp = clp; /* put in nfs4_callback_compound */
>  	for (i = 0; i < args->csa_nrclists; i++)
> 

Re: [PATCH 1/2] nfs: Only update callback sequnce id when CB_SEQUENCE success

[Christoph Hellwig]

Hi Kinglong,

when we last brought up this issue the recommendation was to follow
the model in the clients nfs41_sequence_done() which handles even
more corner cases.  Given that my previous fixes in that area were
just a bandaid I probably shouldn't complain about piece mail handling,
but if you have a little spare time available implementing the full
set of checks might be worthwhile.

Re: [PATCH 1/2] nfs: Only update callback sequnce id when CB_SEQUENCE success

[Kinglong Mee]

On 6/11/2015 4:20 PM, Christoph Hellwig wrote:
> Hi Kinglong,
> 
> when we last brought up this issue the recommendation was to follow
> the model in the clients nfs41_sequence_done() which handles even
> more corner cases.  Given that my previous fixes in that area were
> just a bandaid I probably shouldn't complain about piece mail handling,
> but if you have a little spare time available implementing the full
> set of checks might be worthwhile.

Thank you for your comments.

I have see your patches sits "nfsd: callback fixes". You said process as
nfs41_sequence_done() for handling error cases is server's logical.

Those two patches for NFS client are fix two bugs.

The first one is fix that between validate_seqid() nfs can return error
to nfs server. NFS server cannot make sure whether NFS client has update
the sequence ID.

Also, according to RFC, "If CB_SEQUENCE returns an error, then the state
of the slot (sequence ID, cached reply) MUST NOT change.",
so that this this patch is out.

The second for nfs is fix the initialize problem of cb_sequenceres
when meeting NFS4ERR_RETRY_UNCACHED_REP.

And, other two patches for nfsd, 
The first is fix a infinite loop caused by your last patch I meet.
The second is as you said following to nfs41_sequence_done() maybe better.

thanks
Kinglong Mee

[PATCH] NFS: Ensure that we update the sequence id under the slot table lock

[Trond Myklebust]

Fix a callback slot table regression.

Fixes: e937ee714b2d ("nfs: Only update callback sequnce id when CB_SEQUENCE success")
Cc: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
 fs/nfs/callback_proc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 17a5c571a006..29e3c1b011b7 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -435,14 +435,13 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 	spin_lock(&tbl->slot_tbl_lock);
 	/* state manager is resetting the session */
 	if (test_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state)) {
-		spin_unlock(&tbl->slot_tbl_lock);
 		status = htonl(NFS4ERR_DELAY);
 		/* Return NFS4ERR_BADSESSION if we're draining the session
 		 * in order to reset it.
 		 */
 		if (test_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state))
 			status = htonl(NFS4ERR_BADSESSION);
-		goto out;
+		goto out_unlock;
 	}
 
 	memcpy(&res->csr_sessionid, &args->csa_sessionid,
@@ -453,9 +452,8 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 	res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
 
 	status = validate_seqid(tbl, args);
-	spin_unlock(&tbl->slot_tbl_lock);
 	if (status)
-		goto out;
+		goto out_unlock;
 
 	cps->slotid = args->csa_slotid;
 
@@ -466,7 +464,7 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 	 */
 	if (referring_call_exists(clp, args->csa_nrclists, args->csa_rclists)) {
 		status = htonl(NFS4ERR_DELAY);
-		goto out;
+		goto out_unlock;
 	}
 
 	/*
@@ -475,6 +473,8 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
 	 * (sequence ID, cached reply) MUST NOT change.
 	 */
 	slot->seq_nr++;
+out_unlock:
+	spin_unlock(&tbl->slot_tbl_lock);
 
 out:
 	cps->clp = clp; /* put in nfs4_callback_compound */
-- 
2.4.2