Commit cba5f62b authored by Christoph Hellwig's avatar Christoph Hellwig Committed by J. Bruce Fields
Browse files

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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent ef2a1b3e

fs/nfsd/nfs4callback.c

+23 −29
Original line number Diff line number Diff line
@@ -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)

fs/nfsd/nfs4state.c

+0 −1
Original line number Diff line number Diff line
@@ -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);

fs/nfsd/state.h

+1 −3
Original line number Diff line number Diff line
@@ -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;

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