From: Chuck Lever <chuck.lever@xxxxxxxxxx>
Commit 883820366747 ("nfsd: update workqueue creation") made the
callback_wq single-threaded, presumably to protect modifications of
cl_cb_client. See documenting comment for nfsd4_process_cb_update().
However, cl_cb_client is per-lease. There's no other reason that all
callback operations need to be dispatched via a single thread. The
single threading here means all client callbacks can be blocked by a
problem with one client.
Change the NFSv4 callback client so it serializes per-lease instead
of serializing all NFSv4 callback operations on the server.
Reported-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/nfs4callback.c | 37 +++++++++++++------------------------
fs/nfsd/nfs4state.c | 14 +++++++-------
fs/nfsd/state.h | 4 ++--
3 files changed, 22 insertions(+), 33 deletions(-)
This has seen some light testing with a single client, and has been
pushed to the nfsd-testing branch of:
https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 87c9547989f6..cf87ace7a1b0 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -978,19 +978,21 @@ static int max_cb_time(struct net *net)
return max(((u32)nn->nfsd4_lease)/10, 1u) * HZ;
}
-static struct workqueue_struct *callback_wq;
-
static bool nfsd4_queue_cb(struct nfsd4_callback *cb)
{
- trace_nfsd_cb_queue(cb->cb_clp, cb);
- return queue_delayed_work(callback_wq, &cb->cb_work, 0);
+ struct nfs4_client *clp = cb->cb_clp;
+
+ trace_nfsd_cb_queue(clp, cb);
+ return queue_delayed_work(clp->cl_callback_wq, &cb->cb_work, 0);
}
static void nfsd4_queue_cb_delayed(struct nfsd4_callback *cb,
unsigned long msecs)
{
- trace_nfsd_cb_queue(cb->cb_clp, cb);
- queue_delayed_work(callback_wq, &cb->cb_work,
+ struct nfs4_client *clp = cb->cb_clp;
+
+ trace_nfsd_cb_queue(clp, cb);
+ queue_delayed_work(clp->cl_callback_wq, &cb->cb_work,
msecs_to_jiffies(msecs));
}
@@ -1161,7 +1163,7 @@ void nfsd4_probe_callback(struct nfs4_client *clp)
void nfsd4_probe_callback_sync(struct nfs4_client *clp)
{
nfsd4_probe_callback(clp);
- flush_workqueue(callback_wq);
+ flush_workqueue(clp->cl_callback_wq);
}
void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
@@ -1380,19 +1382,6 @@ static const struct rpc_call_ops nfsd4_cb_ops = {
.rpc_release = nfsd4_cb_release,
};
-int nfsd4_create_callback_queue(void)
-{
- callback_wq = alloc_ordered_workqueue("nfsd4_callbacks", 0);
- if (!callback_wq)
- return -ENOMEM;
- return 0;
-}
-
-void nfsd4_destroy_callback_queue(void)
-{
- destroy_workqueue(callback_wq);
-}
-
/* must be called under the state lock */
void nfsd4_shutdown_callback(struct nfs4_client *clp)
{
@@ -1406,7 +1395,7 @@ void nfsd4_shutdown_callback(struct nfs4_client *clp)
* client, destroy the rpc client, and stop:
*/
nfsd4_run_cb(&clp->cl_cb_null);
- flush_workqueue(callback_wq);
+ flush_workqueue(clp->cl_callback_wq);
nfsd41_cb_inflight_wait_complete(clp);
}
@@ -1428,9 +1417,9 @@ static struct nfsd4_conn * __nfsd4_find_backchannel(struct nfs4_client *clp)
/*
* Note there isn't a lot of locking in this code; instead we depend on
- * the fact that it is run from the callback_wq, which won't run two
- * work items at once. So, for example, callback_wq handles all access
- * of cl_cb_client and all calls to rpc_create or rpc_shutdown_client.
+ * the fact that it is run from clp->cl_callback_wq, which won't run two
+ * work items at once. So, for example, clp->cl_callback_wq handles all
+ * access of cl_cb_client and all calls to rpc_create or rpc_shutdown_client.
*/
static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
{
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 2ece3092a4e3..19e15c093f0a 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2233,6 +2233,10 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name,
GFP_KERNEL);
if (!clp->cl_ownerstr_hashtbl)
goto err_no_hashtbl;
+ clp->cl_callback_wq = alloc_ordered_workqueue("nfsd4_callbacks", 0);
+ if (!clp->cl_callback_wq)
+ goto err_no_callback_wq;
+
for (i = 0; i < OWNER_HASH_SIZE; i++)
INIT_LIST_HEAD(&clp->cl_ownerstr_hashtbl[i]);
INIT_LIST_HEAD(&clp->cl_sessions);
@@ -2255,6 +2259,8 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name,
spin_lock_init(&clp->cl_lock);
rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
return clp;
+err_no_callback_wq:
+ kfree(clp->cl_ownerstr_hashtbl);
err_no_hashtbl:
kfree(clp->cl_name.data);
err_no_name:
@@ -2268,6 +2274,7 @@ static void __free_client(struct kref *k)
struct nfs4_client *clp = container_of(c, struct nfs4_client, cl_nfsdfs);
free_svc_cred(&clp->cl_cred);
+ destroy_workqueue(clp->cl_callback_wq);
kfree(clp->cl_ownerstr_hashtbl);
kfree(clp->cl_name.data);
kfree(clp->cl_nii_domain.data);
@@ -8644,12 +8651,6 @@ nfs4_state_start(void)
if (ret)
return ret;
- ret = nfsd4_create_callback_queue();
- if (ret) {
- rhltable_destroy(&nfs4_file_rhltable);
- return ret;
- }
-
set_max_delegations();
return 0;
}
@@ -8690,7 +8691,6 @@ nfs4_state_shutdown_net(struct net *net)
void
nfs4_state_shutdown(void)
{
- nfsd4_destroy_callback_queue();
rhltable_destroy(&nfs4_file_rhltable);
}
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 0400441c87c1..f42d8d782c84 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -408,6 +408,8 @@ struct nfs4_client {
1 << NFSD4_CLIENT_CB_KILL)
#define NFSD4_CLIENT_CB_RECALL_ANY (6)
unsigned long cl_flags;
+
+ struct workqueue_struct *cl_callback_wq;
const struct cred *cl_cb_cred;
struct rpc_clnt *cl_cb_client;
u32 cl_cb_ident;
@@ -735,8 +737,6 @@ extern void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *
extern void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op);
extern bool nfsd4_run_cb(struct nfsd4_callback *cb);
-extern int nfsd4_create_callback_queue(void);
-extern void nfsd4_destroy_callback_queue(void);
extern void nfsd4_shutdown_callback(struct nfs4_client *);
extern void nfsd4_shutdown_copy(struct nfs4_client *clp);
extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(struct xdr_netobj name,
