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nfsd: fix callback restarts 

Checking the rpc_client pointer is not a reliable way to detect
backchannel changes: cl_cb_client is changed only after shutting down
the rpc client, so the condition cl_cb_client = tk_client will always be
true.

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@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Christoph Hellwig 2015-04-30 11:49:24 +02:00 committed by J. Bruce Fields
parent ef2a1b3e10
commit cba5f62b18
3 changed files with 24 additions and 33 deletions
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48
fs/nfsd/nfs4callback.c
View File

@ -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_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)

1
fs/nfsd/nfs4state.c
View File

@ -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);

4
fs/nfsd/state.h
View File

@ -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;