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Message-Id: <20250129-nfsd-6-14-v2-3-2700c92f3e44@kernel.org>
Date: Wed, 29 Jan 2025 08:39:56 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>,
Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>,
Tom Talpey <tom@...pey.com>, "J. Bruce Fields" <bfields@...ldses.org>,
Kinglong Mee <kinglongmee@...il.com>, Trond Myklebust <trondmy@...nel.org>,
Anna Schumaker <anna@...nel.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v2 3/7] nfsd: add a cb_ses pointer to nfsd4_callback and
use it instead of clp->cb_cb_session
Once a callback workqueue job has completed, the cl_cb_session could
change to a completely different session, if there is more than one
callback in flight at a time.
Have the callback hold its own cb reference to the session, and fix the
slot acquisition routines to get/put a session reference. This ensures
that the call and reply handling are working with the same session.
In the event that rpc_prepare can't get a session reference, allow the
rpc_task to sleep until the session reference changes.
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
fs/nfsd/nfs4callback.c | 67 +++++++++++++++++++++++++++++++++++++++++---------
fs/nfsd/state.h | 1 +
fs/nfsd/trace.h | 6 ++---
3 files changed, 58 insertions(+), 16 deletions(-)
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index e55bf66a33d6efb56d2f75f0a49a60307e3807ac..9f4838a6d9c668cdf66a77793f63c064586f2b22 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -435,7 +435,7 @@ static void encode_cb_sequence4args(struct xdr_stream *xdr,
const struct nfsd4_callback *cb,
struct nfs4_cb_compound_hdr *hdr)
{
- struct nfsd4_session *session = cb->cb_clp->cl_cb_session;
+ struct nfsd4_session *session = cb->cb_ses;
__be32 *p;
if (hdr->minorversion == 0)
@@ -503,7 +503,7 @@ static void update_cb_slot_table(struct nfsd4_session *ses, u32 target)
static int decode_cb_sequence4resok(struct xdr_stream *xdr,
struct nfsd4_callback *cb)
{
- struct nfsd4_session *session = cb->cb_clp->cl_cb_session;
+ struct nfsd4_session *session = cb->cb_ses;
int status = -ESERVERFAULT;
__be32 *p;
u32 seqid, slotid, target;
@@ -1142,7 +1142,7 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c
return -EINVAL;
rcu_assign_pointer(clp->cl_cb_session, ses);
args.bc_xprt = conn->cb_xprt;
- args.prognumber = clp->cl_cb_session->se_cb_prog;
+ args.prognumber = ses->se_cb_prog;
args.protocol = conn->cb_xprt->xpt_class->xcl_ident |
XPRT_TRANSPORT_BC;
args.authflavor = ses->se_cb_sec.flavor;
@@ -1161,9 +1161,10 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c
ret = -ENOMEM;
goto out_put_ses;
}
-
- if (clp->cl_minorversion != 0)
+ if (clp->cl_minorversion != 0) {
clp->cl_cb_conn.cb_xprt = conn->cb_xprt;
+ rpc_wake_up(&clp->cl_cb_waitq);
+ }
clp->cl_cb_client = client;
clp->cl_cb_cred = cred;
rcu_read_lock();
@@ -1252,6 +1253,34 @@ void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
spin_unlock(&clp->cl_lock);
}
+static bool grab_cb_ses(struct nfsd4_callback *cb)
+{
+ struct nfs4_client *clp = cb->cb_clp;
+ struct nfsd4_session *ses;
+ bool ret = false;
+
+ if (cb->cb_ses)
+ return true;
+
+ rcu_read_lock();
+ ses = rcu_dereference(clp->cl_cb_session);
+ if (ses && nfsd4_cb_get_session(ses)) {
+ cb->cb_ses = ses;
+ ret = true;
+ }
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static void put_cb_ses(struct nfsd4_callback *cb)
+{
+ if (cb->cb_ses) {
+ nfsd4_cb_put_session(cb->cb_ses);
+ cb->cb_ses = NULL;
+ }
+}
+
static int grab_slot(struct nfsd4_session *ses)
{
int idx;
@@ -1269,24 +1298,33 @@ static int grab_slot(struct nfsd4_session *ses)
}
/*
- * There's currently a single callback channel slot.
- * If the slot is available, then mark it busy. Otherwise, set the
- * thread for sleeping on the callback RPC wait queue.
+ * Get both a session reference and a slot.
*/
static bool nfsd41_cb_get_slot(struct nfsd4_callback *cb, struct rpc_task *task)
{
struct nfs4_client *clp = cb->cb_clp;
- struct nfsd4_session *ses = clp->cl_cb_session;
+ struct nfsd4_session *ses;
+
+ if (!grab_cb_ses(cb)) {
+ rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
+ if (!grab_cb_ses(cb))
+ return false;
+ rpc_wake_up_queued_task(&clp->cl_cb_waitq, task);
+ }
if (cb->cb_held_slot >= 0)
return true;
+
+ ses = cb->cb_ses;
cb->cb_held_slot = grab_slot(ses);
if (cb->cb_held_slot < 0) {
rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
/* Race breaker */
cb->cb_held_slot = grab_slot(ses);
- if (cb->cb_held_slot < 0)
+ if (cb->cb_held_slot < 0) {
+ put_cb_ses(cb);
return false;
+ }
rpc_wake_up_queued_task(&clp->cl_cb_waitq, task);
}
return true;
@@ -1295,7 +1333,10 @@ static bool nfsd41_cb_get_slot(struct nfsd4_callback *cb, struct rpc_task *task)
static void nfsd41_cb_release_slot(struct nfsd4_callback *cb)
{
struct nfs4_client *clp = cb->cb_clp;
- struct nfsd4_session *ses = clp->cl_cb_session;
+ struct nfsd4_session *ses = cb->cb_ses;
+
+ if (!ses)
+ return;
if (cb->cb_held_slot >= 0) {
spin_lock(&ses->se_lock);
@@ -1304,6 +1345,7 @@ static void nfsd41_cb_release_slot(struct nfsd4_callback *cb)
cb->cb_held_slot = -1;
rpc_wake_up_next(&clp->cl_cb_waitq);
}
+ put_cb_ses(cb);
}
static void nfsd41_destroy_cb(struct nfsd4_callback *cb)
@@ -1342,7 +1384,7 @@ static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback *cb)
{
struct nfs4_client *clp = cb->cb_clp;
- struct nfsd4_session *session = clp->cl_cb_session;
+ struct nfsd4_session *session = cb->cb_ses;
bool ret = true;
if (!clp->cl_minorversion) {
@@ -1629,6 +1671,7 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op)
{
cb->cb_clp = clp;
+ cb->cb_ses = NULL;
cb->cb_msg.rpc_proc = &nfs4_cb_procedures[op];
cb->cb_msg.rpc_argp = cb;
cb->cb_msg.rpc_resp = cb;
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 0faa367c9fa3280fa4a8a982f974804bb89f2035..56fe34d8dd90344404512114113c00a027aeb6a4 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -66,6 +66,7 @@ typedef struct {
struct nfsd4_callback {
struct nfs4_client *cb_clp;
+ struct nfsd4_session *cb_ses;
struct rpc_message cb_msg;
const struct nfsd4_callback_ops *cb_ops;
struct work_struct cb_work;
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index ad2c0c432d08705bcebf00f7309f19267afcae03..fff665bac3b252387f92139b5f868cf1b034d1c9 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -1644,8 +1644,7 @@ TRACE_EVENT(nfsd_cb_seq_status,
__field(int, seq_status)
),
TP_fast_assign(
- const struct nfs4_client *clp = cb->cb_clp;
- const struct nfsd4_session *session = clp->cl_cb_session;
+ const struct nfsd4_session *session = cb->cb_ses;
const struct nfsd4_sessionid *sid =
(struct nfsd4_sessionid *)&session->se_sessionid;
@@ -1684,8 +1683,7 @@ TRACE_EVENT(nfsd_cb_free_slot,
__field(u32, slot_seqno)
),
TP_fast_assign(
- const struct nfs4_client *clp = cb->cb_clp;
- const struct nfsd4_session *session = clp->cl_cb_session;
+ const struct nfsd4_session *session = cb->cb_ses;
const struct nfsd4_sessionid *sid =
(struct nfsd4_sessionid *)&session->se_sessionid;
--
2.48.1
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