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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>
This commit is contained in:
Andy Adamson 2009-12-04 15:55:38 -05:00 committed by Trond Myklebust
parent 05f0d23647
commit ea028ac925
4 changed files with 34 additions and 9 deletions
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1
fs/nfs/nfs4_fs.h
View File

@ -45,6 +45,7 @@ enum nfs4_client_state {
NFS4CLNT_RECLAIM_NOGRACE,
NFS4CLNT_DELEGRETURN,
NFS4CLNT_SESSION_RESET,
NFS4CLNT_SESSION_DRAINING,
};
/*

26
fs/nfs/nfs4proc.c
View File

@ -361,6 +361,16 @@ void nfs41_sequence_free_slot(const struct nfs_client *clp,
}
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 @@ static int nfs41_setup_sequence(struct nfs4_session *session,
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 @@ static int nfs4_reset_slot_tables(struct nfs4_session *session)
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 @@ struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
* 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);

15
fs/nfs/nfs4state.c
View File

@ -1181,8 +1181,23 @@ static void nfs4_session_recovery_handle_error(struct nfs_client *clp, int err)
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) {

1
include/linux/nfs_fs_sb.h
View File

@ -209,6 +209,7 @@ struct nfs4_session {
unsigned long session_state;
u32 hash_alg;
u32 ssv_len;
struct completion complete;
/* The fore and back channel */
struct nfs4_channel_attrs fc_attrs;