Checking the rpc_client pointer is not a reliable way to detect a backchannel
connetion failure, as the likelyhood of reusing the same slab object is
very high. Check the RPC_TASK_KILLED flag instead, and rewrite the code to
avoid the buggy cl_callbacks list and fix the lifetime rules due to double
calls of the ->prepare callback operations method for this retry case.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/nfsd/nfs4callback.c | 52 ++++++++++++++++++++++----------------------------
fs/nfsd/nfs4state.c | 1 -
fs/nfsd/state.h | 4 +---
3 files changed, 24 insertions(+), 33 deletions(-)
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index cd58b7c..4c993aa 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -879,13 +879,6 @@ static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
if (!nfsd41_cb_get_slot(clp, task))
return;
}
- spin_lock(&clp->cl_lock);
- if (list_empty(&cb->cb_per_client)) {
- /* This is the first call, not a restart */
- cb->cb_done = false;
- list_add(&cb->cb_per_client, &clp->cl_callbacks);
- }
- spin_unlock(&clp->cl_lock);
rpc_call_start(task);
}
@@ -907,16 +900,21 @@ static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
clp->cl_cb_session->se_cb_seq_nr);
}
- if (clp->cl_cb_client != task->tk_client) {
- /* We're shutting down or changing cl_cb_client; leave
- * it to nfsd4_process_cb_update to restart the call if
- * necessary. */
+ /*
+ * If the backchannel connection was shut down while this
+ * task was queued, we need to resubmit it after setting up
+ * a new backchannel connection.
+ *
+ * Note that if we lost our callback connection permanently
+ * the submission code will error out, so we don't need to
+ * handle that case here.
+ */
+ if (task->tk_flags & RPC_TASK_KILLED) {
+ task->tk_status = 0;
+ cb->cb_need_restart = true;
return;
}
- if (cb->cb_done)
- return;
-
if (cb->cb_status) {
WARN_ON_ONCE(task->tk_status);
task->tk_status = cb->cb_status;
@@ -936,21 +934,17 @@ static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
default:
BUG();
}
- cb->cb_done = true;
}
static void nfsd4_cb_release(void *calldata)
{
struct nfsd4_callback *cb = calldata;
- struct nfs4_client *clp = cb->cb_clp;
-
- if (cb->cb_done) {
- spin_lock(&clp->cl_lock);
- list_del(&cb->cb_per_client);
- spin_unlock(&clp->cl_lock);
+ if (cb->cb_need_restart)
+ nfsd4_run_cb(cb);
+ else
cb->cb_ops->release(cb);
- }
+
}
static const struct rpc_call_ops nfsd4_cb_ops = {
@@ -1045,9 +1039,6 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
nfsd4_mark_cb_down(clp, err);
return;
}
- /* Yay, the callback channel's back! Restart any callbacks: */
- list_for_each_entry(cb, &clp->cl_callbacks, cb_per_client)
- queue_work(callback_wq, &cb->cb_work);
}
static void
@@ -1058,8 +1049,12 @@ nfsd4_run_cb_work(struct work_struct *work)
struct nfs4_client *clp = cb->cb_clp;
struct rpc_clnt *clnt;
- if (cb->cb_ops && cb->cb_ops->prepare)
- cb->cb_ops->prepare(cb);
+ if (cb->cb_need_restart) {
+ cb->cb_need_restart = false;
+ } else {
+ if (cb->cb_ops && cb->cb_ops->prepare)
+ cb->cb_ops->prepare(cb);
+ }
if (clp->cl_flags & NFSD4_CLIENT_CB_FLAG_MASK)
nfsd4_process_cb_update(cb);
@@ -1085,9 +1080,8 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
cb->cb_msg.rpc_resp = cb;
cb->cb_ops = ops;
INIT_WORK(&cb->cb_work, nfsd4_run_cb_work);
- INIT_LIST_HEAD(&cb->cb_per_client);
cb->cb_status = 0;
- cb->cb_done = true;
+ cb->cb_need_restart = false;
}
void nfsd4_run_cb(struct nfsd4_callback *cb)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9072964..2bad0a1 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1626,7 +1626,6 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
INIT_LIST_HEAD(&clp->cl_openowners);
INIT_LIST_HEAD(&clp->cl_delegations);
INIT_LIST_HEAD(&clp->cl_lru);
- INIT_LIST_HEAD(&clp->cl_callbacks);
INIT_LIST_HEAD(&clp->cl_revoked);
#ifdef CONFIG_NFSD_PNFS
INIT_LIST_HEAD(&clp->cl_lo_states);
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index e791985..dbc4f85 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -63,13 +63,12 @@ typedef struct {
struct nfsd4_callback {
struct nfs4_client *cb_clp;
- struct list_head cb_per_client;
u32 cb_minorversion;
struct rpc_message cb_msg;
struct nfsd4_callback_ops *cb_ops;
struct work_struct cb_work;
int cb_status;
- bool cb_done;
+ bool cb_need_restart;
};
struct nfsd4_callback_ops {
@@ -334,7 +333,6 @@ struct nfs4_client {
int cl_cb_state;
struct nfsd4_callback cl_cb_null;
struct nfsd4_session *cl_cb_session;
- struct list_head cl_callbacks; /* list of in-progress callbacks */
/* for all client information that callback code might need: */
spinlock_t cl_lock;
--
1.9.1
--
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