[ 3.5.y.z extended stable ] Patch "NFS: Add sequence_priviliged_ops for nfs4_proc_sequence()" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    NFS: Add sequence_priviliged_ops for nfs4_proc_sequence()

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 5e5195cad4f77a11c34617acb65be18489096e0b Mon Sep 17 00:00:00 2001
From: Bryan Schumaker <bjschuma at netapp.com>
Date: Mon, 12 Nov 2012 16:55:38 -0500
Subject: [PATCH] NFS: Add sequence_priviliged_ops for nfs4_proc_sequence()

commit 6bdb5f213c4344324f600dde885f25768fbd14db upstream.

If I mount an NFS v4.1 server to a single client multiple times and then
run xfstests over each mountpoint I usually get the client into a state
where recovery deadlocks.  The server informs the client of a
cb_path_down sequence error, the client then does a
bind_connection_to_session and checks the status of the lease.

I found that bind_connection_to_session sets the NFS4_SESSION_DRAINING
flag on the client, but this flag is never unset before
nfs4_check_lease() reaches nfs4_proc_sequence().  This causes the client
to deadlock, halting all NFS activity to the server.  nfs4_proc_sequence()
is only called by the state manager, so I can change it to run in privileged
mode to bypass the NFS4_SESSION_DRAINING check and avoid the deadlock.

Signed-off-by: Bryan Schumaker <bjschuma at netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust at netapp.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 fs/nfs/nfs4proc.c |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 9b1ac5c..c1bad65 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5937,13 +5937,26 @@ static void nfs41_sequence_prepare(struct rpc_task *task, void *data)
 	rpc_call_start(task);
 }

+static void nfs41_sequence_prepare_privileged(struct rpc_task *task, void *data)
+{
+	rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
+	nfs41_sequence_prepare(task, data);
+}
+
 static const struct rpc_call_ops nfs41_sequence_ops = {
 	.rpc_call_done = nfs41_sequence_call_done,
 	.rpc_call_prepare = nfs41_sequence_prepare,
 	.rpc_release = nfs41_sequence_release,
 };

-static struct rpc_task *_nfs41_proc_sequence(struct nfs_client *clp, struct rpc_cred *cred)
+static const struct rpc_call_ops nfs41_sequence_privileged_ops = {
+	.rpc_call_done = nfs41_sequence_call_done,
+	.rpc_call_prepare = nfs41_sequence_prepare_privileged,
+	.rpc_release = nfs41_sequence_release,
+};
+
+static struct rpc_task *_nfs41_proc_sequence(struct nfs_client *clp, struct rpc_cred *cred,
+					     const struct rpc_call_ops *seq_ops)
 {
 	struct nfs4_sequence_data *calldata;
 	struct rpc_message msg = {
@@ -5953,7 +5966,7 @@ static struct rpc_task *_nfs41_proc_sequence(struct nfs_client *clp, struct rpc_
 	struct rpc_task_setup task_setup_data = {
 		.rpc_client = clp->cl_rpcclient,
 		.rpc_message = &msg,
-		.callback_ops = &nfs41_sequence_ops,
+		.callback_ops = seq_ops,
 		.flags = RPC_TASK_ASYNC | RPC_TASK_SOFT,
 	};

@@ -5980,7 +5993,7 @@ static int nfs41_proc_async_sequence(struct nfs_client *clp, struct rpc_cred *cr

 	if ((renew_flags & NFS4_RENEW_TIMEOUT) == 0)
 		return 0;
-	task = _nfs41_proc_sequence(clp, cred);
+	task = _nfs41_proc_sequence(clp, cred, &nfs41_sequence_ops);
 	if (IS_ERR(task))
 		ret = PTR_ERR(task);
 	else
@@ -5994,7 +6007,7 @@ static int nfs4_proc_sequence(struct nfs_client *clp, struct rpc_cred *cred)
 	struct rpc_task *task;
 	int ret;

-	task = _nfs41_proc_sequence(clp, cred);
+	task = _nfs41_proc_sequence(clp, cred, &nfs41_sequence_privileged_ops);
 	if (IS_ERR(task)) {
 		ret = PTR_ERR(task);
 		goto out;
--
1.7.9.5