2015-03-04 02:54:07

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH 1/2] NFSv4: Fix a race in NFSv4.1 server trunking discovery

We do not want to allow a race with another NFS mount to cause
nfs41_walk_client_list() to establish a lease on our nfs_client before
we're done checking for trunking.

Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/client.c | 2 +-
fs/nfs/nfs4client.c | 9 ++++-----
fs/nfs/nfs4state.c | 14 ++++++++++++--
3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index f9f4845db989..19874151e95c 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -433,7 +433,7 @@ static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *dat

static bool nfs_client_init_is_complete(const struct nfs_client *clp)
{
- return clp->cl_cons_state != NFS_CS_INITING;
+ return clp->cl_cons_state <= NFS_CS_READY;
}

int nfs_wait_client_init_complete(const struct nfs_client *clp)
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 8646af9b11d2..86d6214ea022 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -621,6 +621,9 @@ int nfs41_walk_client_list(struct nfs_client *new,
spin_lock(&nn->nfs_client_lock);
list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {

+ if (pos == new)
+ goto found;
+
if (pos->rpc_ops != new->rpc_ops)
continue;

@@ -639,10 +642,6 @@ int nfs41_walk_client_list(struct nfs_client *new,
prev = pos;

status = nfs_wait_client_init_complete(pos);
- if (pos->cl_cons_state == NFS_CS_SESSION_INITING) {
- nfs4_schedule_lease_recovery(pos);
- status = nfs4_wait_clnt_recover(pos);
- }
spin_lock(&nn->nfs_client_lock);
if (status < 0)
break;
@@ -668,7 +667,7 @@ int nfs41_walk_client_list(struct nfs_client *new,
*/
if (!nfs4_match_client_owner_id(pos, new))
continue;
-
+found:
atomic_inc(&pos->cl_count);
*result = pos;
status = 0;
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 5ad908e9ce9c..d8b43f0e08fc 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -346,9 +346,19 @@ int nfs41_discover_server_trunking(struct nfs_client *clp,
status = nfs4_proc_exchange_id(clp, cred);
if (status != NFS4_OK)
return status;
- set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);

- return nfs41_walk_client_list(clp, result, cred);
+ status = nfs41_walk_client_list(clp, result, cred);
+ if (status < 0)
+ return status;
+ if (clp != *result)
+ return 0;
+
+ set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+ nfs4_schedule_state_manager(clp);
+ status = nfs_wait_client_init_complete(clp);
+ if (status < 0)
+ nfs_put_client(clp);
+ return status;
}

#endif /* CONFIG_NFS_V4_1 */
--
2.1.0



2015-03-04 02:54:08

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH 2/2] NFSv4.1: Clear the old state by our client id before establishing a new lease

If the call to exchange-id returns with the EXCHGID4_FLAG_CONFIRMED_R flag
set, then that means our lease was established by a previous mount instance.
Ensure that we detect this situation, and that we clear the state held by
that mount.

Reported-by: Jorge Mora <[email protected]>
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/nfs4proc.c | 15 +++++++++++----
fs/nfs/nfs4session.h | 1 +
fs/nfs/nfs4state.c | 6 +++++-
3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 732526e04cd5..627f37c44456 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6897,9 +6897,13 @@ static int _nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred,

if (status == 0) {
clp->cl_clientid = res.clientid;
- clp->cl_exchange_flags = (res.flags & ~EXCHGID4_FLAG_CONFIRMED_R);
- if (!(res.flags & EXCHGID4_FLAG_CONFIRMED_R))
+ clp->cl_exchange_flags = res.flags;
+ /* Client ID is not confirmed */
+ if (!(res.flags & EXCHGID4_FLAG_CONFIRMED_R)) {
+ clear_bit(NFS4_SESSION_ESTABLISHED,
+ &clp->cl_session->session_state);
clp->cl_seqid = res.seqid;
+ }

kfree(clp->cl_serverowner);
clp->cl_serverowner = res.server_owner;
@@ -7231,6 +7235,9 @@ static void nfs4_update_session(struct nfs4_session *session,
struct nfs41_create_session_res *res)
{
nfs4_copy_sessionid(&session->sess_id, &res->sessionid);
+ /* Mark client id and session as being confirmed */
+ session->clp->cl_exchange_flags |= EXCHGID4_FLAG_CONFIRMED_R;
+ set_bit(NFS4_SESSION_ESTABLISHED, &session->session_state);
session->flags = res->flags;
memcpy(&session->fc_attrs, &res->fc_attrs, sizeof(session->fc_attrs));
if (res->flags & SESSION4_BACK_CHAN)
@@ -7326,8 +7333,8 @@ int nfs4_proc_destroy_session(struct nfs4_session *session,
dprintk("--> nfs4_proc_destroy_session\n");

/* session is still being setup */
- if (session->clp->cl_cons_state != NFS_CS_READY)
- return status;
+ if (!test_and_clear_bit(NFS4_SESSION_ESTABLISHED, &session->session_state))
+ return 0;

status = rpc_call_sync(session->clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
trace_nfs4_destroy_session(session->clp, status);
diff --git a/fs/nfs/nfs4session.h b/fs/nfs/nfs4session.h
index fc46c7455898..e3ea2c5324d6 100644
--- a/fs/nfs/nfs4session.h
+++ b/fs/nfs/nfs4session.h
@@ -70,6 +70,7 @@ struct nfs4_session {

enum nfs4_session_state {
NFS4_SESSION_INITING,
+ NFS4_SESSION_ESTABLISHED,
};

extern int nfs4_setup_slot_table(struct nfs4_slot_table *tbl,
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index d8b43f0e08fc..f95e3b58bbc3 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -353,7 +353,11 @@ int nfs41_discover_server_trunking(struct nfs_client *clp,
if (clp != *result)
return 0;

- set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
+ /* Purge state if the client id was established in a prior instance */
+ if (clp->cl_exchange_flags & EXCHGID4_FLAG_CONFIRMED_R)
+ set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
+ else
+ set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
nfs4_schedule_state_manager(clp);
status = nfs_wait_client_init_complete(clp);
if (status < 0)
--
2.1.0