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nfsd4: Move callback setup to callback queue

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Instead of creating the new rpc client from a regular server thread,
set a flag, kick off a null call, and allow the null call to do the work
of setting up the client on the callback workqueue.

Use a spinlock to ensure the callback work gets a consistent view of the
callback parameters.

This allows, for example, changing the callback from contexts where
sleeping is not allowed.  I hope it will also keep the locking simple as
we add more session and trunking features, by serializing most of the
callback-specific work.

This also closes a small race where the the new cb_ident could be used
with an old connection (or vice-versa).

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
J. Bruce Fields
2010-06-04 20:04:45 -04:00
committed by J. Bruce Fields
parent fb00392326
commit 6ff8da0887
3 changed files with 63 additions and 27 deletions
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73
fs/nfsd/nfs4callback.c
View File

@@ -284,7 +284,7 @@ nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
struct xdr_stream xdr;
struct nfs4_delegation *args = cb->cb_op;
struct nfs4_cb_compound_hdr hdr = {
.ident = args->dl_ident,
.ident = cb->cb_clp->cl_cb_ident,
.minorversion = cb->cb_minorversion,
};
@@ -506,7 +506,8 @@ int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
PTR_ERR(client));
return PTR_ERR(client);
}
nfsd4_set_callback_client(clp, client);
clp->cl_cb_ident = conn->cb_ident;
clp->cl_cb_client = client;
return 0;
}
@@ -569,15 +570,12 @@ void do_probe_callback(struct nfs4_client *clp)
*/
void nfsd4_probe_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
{
int status;
BUG_ON(atomic_read(&clp->cl_cb_set));
status = setup_callback_client(clp, conn);
if (status) {
warn_no_callback_path(clp, status);
return;
}
spin_lock(&clp->cl_lock);
memcpy(&clp->cl_cb_conn, conn, sizeof(struct nfs4_cb_conn));
set_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_cb_flags);
spin_unlock(&clp->cl_lock);
do_probe_callback(clp);
}
@@ -730,19 +728,16 @@ void nfsd4_destroy_callback_queue(void)
}
/* must be called under the state lock */
void nfsd4_set_callback_client(struct nfs4_client *clp, struct rpc_clnt *new)
void nfsd4_shutdown_callback(struct nfs4_client *clp)
{
struct rpc_clnt *old = clp->cl_cb_client;
clp->cl_cb_client = new;
set_bit(NFSD4_CLIENT_KILL, &clp->cl_cb_flags);
/*
* After this, any work that saw the old value of cl_cb_client will
* be gone:
* Note this won't actually result in a null callback;
* instead, nfsd4_do_callback_rpc() will detect the killed
* client, destroy the rpc client, and stop:
*/
do_probe_callback(clp);
flush_workqueue(callback_wq);
/* So we can safely shut it down: */
if (old)
rpc_shutdown_client(old);
}
void nfsd4_release_cb(struct nfsd4_callback *cb)
@@ -751,15 +746,51 @@ void nfsd4_release_cb(struct nfsd4_callback *cb)
cb->cb_ops->rpc_release(cb);
}
void nfsd4_process_cb_update(struct nfsd4_callback *cb)
{
struct nfs4_cb_conn conn;
struct nfs4_client *clp = cb->cb_clp;
int err;
/*
* This is either an update, or the client dying; in either case,
* kill the old client:
*/
if (clp->cl_cb_client) {
rpc_shutdown_client(clp->cl_cb_client);
clp->cl_cb_client = NULL;
}
if (test_bit(NFSD4_CLIENT_KILL, &clp->cl_cb_flags))
return;
spin_lock(&clp->cl_lock);
/*
* Only serialized callback code is allowed to clear these
* flags; main nfsd code can only set them:
*/
BUG_ON(!clp->cl_cb_flags);
clear_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_cb_flags);
memcpy(&conn, &cb->cb_clp->cl_cb_conn, sizeof(struct nfs4_cb_conn));
spin_unlock(&clp->cl_lock);
err = setup_callback_client(clp, &conn);
if (err)
warn_no_callback_path(clp, err);
}
void nfsd4_do_callback_rpc(struct work_struct *w)
{
struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work);
struct nfs4_client *clp = cb->cb_clp;
struct rpc_clnt *clnt = clp->cl_cb_client;
struct rpc_clnt *clnt;
if (clnt == NULL) {
if (clp->cl_cb_flags)
nfsd4_process_cb_update(cb);
clnt = clp->cl_cb_client;
if (!clnt) {
/* Callback channel broken, or client killed; give up: */
nfsd4_release_cb(cb);
return; /* Client is shutting down; give up. */
return;
}
rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
cb->cb_ops, cb);