nfs41: nfs41: fix state manager deadlock in session reset
If the session is reset during state recovery, the state manager thread can
sleep on the slot_tbl_waitq causing a deadlock.
Add a completion framework to the session. Have the state manager thread set
a new session state (NFS4CLNT_SESSION_DRAINING) and wait for the session slot
table to drain.
Signal the state manager thread in nfs41_sequence_free_slot when the
NFS4CLNT_SESSION_DRAINING bit is set and the session is drained.
Reported-by: Trond Myklebust <trond@netapp.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index e9ecd6b..5c77401 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -45,6 +45,7 @@
NFS4CLNT_RECLAIM_NOGRACE,
NFS4CLNT_DELEGRETURN,
NFS4CLNT_SESSION_RESET,
+ NFS4CLNT_SESSION_DRAINING,
};
/*
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index fb62919..c1bc9ca 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -361,6 +361,16 @@
}
nfs4_free_slot(tbl, res->sr_slotid);
res->sr_slotid = NFS4_MAX_SLOT_TABLE;
+
+ /* Signal state manager thread if session is drained */
+ if (test_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state)) {
+ spin_lock(&tbl->slot_tbl_lock);
+ if (tbl->highest_used_slotid == -1) {
+ dprintk("%s COMPLETE: Session Drained\n", __func__);
+ complete(&clp->cl_session->complete);
+ }
+ spin_unlock(&tbl->slot_tbl_lock);
+ }
}
static void nfs41_sequence_done(struct nfs_client *clp,
@@ -457,15 +467,11 @@
spin_lock(&tbl->slot_tbl_lock);
if (test_bit(NFS4CLNT_SESSION_RESET, &session->clp->cl_state)) {
- if (tbl->highest_used_slotid != -1) {
- rpc_sleep_on(&tbl->slot_tbl_waitq, task, NULL);
- spin_unlock(&tbl->slot_tbl_lock);
- dprintk("<-- %s: Session reset: draining\n", __func__);
- return -EAGAIN;
- }
-
- /* The slot table is empty; start the reset thread */
- dprintk("%s Session Reset\n", __func__);
+ /*
+ * The state manager will wait until the slot table is empty.
+ * Schedule the reset thread
+ */
+ dprintk("%s Schedule Session Reset\n", __func__);
rpc_sleep_on(&tbl->slot_tbl_waitq, task, NULL);
nfs4_schedule_state_manager(session->clp);
spin_unlock(&tbl->slot_tbl_lock);
@@ -4506,6 +4512,7 @@
1);
if (status)
return status;
+ init_completion(&session->complete);
status = nfs4_reset_slot_table(&session->bc_slot_table,
session->bc_attrs.max_reqs,
@@ -4608,6 +4615,7 @@
* nfs_client struct
*/
clp->cl_cons_state = NFS_CS_SESSION_INITING;
+ init_completion(&session->complete);
tbl = &session->fc_slot_table;
spin_lock_init(&tbl->slot_tbl_lock);
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index f56f6be..3c14335 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1181,8 +1181,23 @@
static int nfs4_reset_session(struct nfs_client *clp)
{
+ struct nfs4_session *ses = clp->cl_session;
+ struct nfs4_slot_table *tbl = &ses->fc_slot_table;
int status;
+ INIT_COMPLETION(ses->complete);
+ spin_lock(&tbl->slot_tbl_lock);
+ if (tbl->highest_used_slotid != -1) {
+ set_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state);
+ spin_unlock(&tbl->slot_tbl_lock);
+ status = wait_for_completion_interruptible(&ses->complete);
+ clear_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state);
+ if (status) /* -ERESTARTSYS */
+ goto out;
+ } else {
+ spin_unlock(&tbl->slot_tbl_lock);
+ }
+
status = nfs4_proc_destroy_session(clp->cl_session);
if (status && status != -NFS4ERR_BADSESSION &&
status != -NFS4ERR_DEADSESSION) {