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nfsd: Fix races between nfsd4_cb_release() and nfsd4_shutdown_callback()

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When we're destroying the client lease, and we call
nfsd4_shutdown_callback(), we must ensure that we do not return
before all outstanding callbacks have terminated and have
released their payloads.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Trond Myklebust 2019-10-23 17:43:18 -04:00 committed by J. Bruce Fields
parent 12357f1b2c
commit 2bbfed98a4
2 changed files with 59 additions and 9 deletions
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63
fs/nfsd/nfs4callback.c
View File

@ -826,6 +826,31 @@ static int max_cb_time(struct net *net)
return max(nn->nfsd4_lease/10, (time_t)1) * HZ;
}
static struct workqueue_struct *callback_wq;
static bool nfsd4_queue_cb(struct nfsd4_callback *cb)
{
return queue_work(callback_wq, &cb->cb_work);
}
static void nfsd41_cb_inflight_begin(struct nfs4_client *clp)
{
atomic_inc(&clp->cl_cb_inflight);
}
static void nfsd41_cb_inflight_end(struct nfs4_client *clp)
{
if (atomic_dec_and_test(&clp->cl_cb_inflight))
wake_up_var(&clp->cl_cb_inflight);
}
static void nfsd41_cb_inflight_wait_complete(struct nfs4_client *clp)
{
wait_var_event(&clp->cl_cb_inflight,
!atomic_read(&clp->cl_cb_inflight));
}
static const struct cred *get_backchannel_cred(struct nfs4_client *clp, struct rpc_clnt *client, struct nfsd4_session *ses)
{
if (clp->cl_minorversion == 0) {
@ -937,14 +962,21 @@ static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
clp->cl_cb_state = NFSD4_CB_UP;
}
static void nfsd4_cb_probe_release(void *calldata)
{
struct nfs4_client *clp = container_of(calldata, struct nfs4_client, cl_cb_null);
nfsd41_cb_inflight_end(clp);
}
static const struct rpc_call_ops nfsd4_cb_probe_ops = {
/* XXX: release method to ensure we set the cb channel down if
* necessary on early failure? */
.rpc_call_done = nfsd4_cb_probe_done,
.rpc_release = nfsd4_cb_probe_release,
};
static struct workqueue_struct *callback_wq;
/*
* Poke the callback thread to process any updates to the callback
* parameters, and send a null probe.
@ -1004,6 +1036,16 @@ static void nfsd41_cb_release_slot(struct nfsd4_callback *cb)
}
}
static void nfsd41_destroy_cb(struct nfsd4_callback *cb)
{
struct nfs4_client *clp = cb->cb_clp;
nfsd41_cb_release_slot(cb);
if (cb->cb_ops && cb->cb_ops->release)
cb->cb_ops->release(cb);
nfsd41_cb_inflight_end(clp);
}
/*
* TODO: cb_sequence should support referring call lists, cachethis, multiple
* slots, and mark callback channel down on communication errors.
@ -1101,8 +1143,10 @@ retry_nowait:
ret = false;
goto out;
need_restart:
if (!test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags)) {
task->tk_status = 0;
cb->cb_need_restart = true;
}
return false;
}
@ -1144,9 +1188,9 @@ static void nfsd4_cb_release(void *calldata)
struct nfsd4_callback *cb = calldata;
if (cb->cb_need_restart)
nfsd4_run_cb(cb);
nfsd4_queue_cb(cb);
else
cb->cb_ops->release(cb);
nfsd41_destroy_cb(cb);
}
@ -1180,6 +1224,7 @@ void nfsd4_shutdown_callback(struct nfs4_client *clp)
*/
nfsd4_run_cb(&clp->cl_cb_null);
flush_workqueue(callback_wq);
nfsd41_cb_inflight_wait_complete(clp);
}
/* requires cl_lock: */
@ -1265,8 +1310,7 @@ nfsd4_run_cb_work(struct work_struct *work)
clnt = clp->cl_cb_client;
if (!clnt) {
/* Callback channel broken, or client killed; give up: */
if (cb->cb_ops && cb->cb_ops->release)
cb->cb_ops->release(cb);
nfsd41_destroy_cb(cb);
return;
}
@ -1275,6 +1319,7 @@ nfsd4_run_cb_work(struct work_struct *work)
*/
if (!cb->cb_ops && clp->cl_minorversion) {
clp->cl_cb_state = NFSD4_CB_UP;
nfsd41_destroy_cb(cb);
return;
}
@ -1300,5 +1345,9 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
void nfsd4_run_cb(struct nfsd4_callback *cb)
{
queue_work(callback_wq, &cb->cb_work);
struct nfs4_client *clp = cb->cb_clp;
nfsd41_cb_inflight_begin(clp);
if (!nfsd4_queue_cb(cb))
nfsd41_cb_inflight_end(clp);
}

1
fs/nfsd/state.h
View File

@ -367,6 +367,7 @@ struct nfs4_client {
struct net *net;
struct list_head async_copies; /* list of async copies */
spinlock_t async_lock; /* lock for async copies */
atomic_t cl_cb_inflight; /* Outstanding callbacks */
};
/* struct nfs4_client_reset