From ea028ac92541ac30bf202ed94cb53eec2ea0c9d6 Mon Sep 17 00:00:00 2001 From: Andy Adamson Date: Fri, 4 Dec 2009 15:55:38 -0500 Subject: 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 Signed-off-by: Andy Adamson Signed-off-by: Trond Myklebust --- fs/nfs/nfs4_fs.h | 1 + fs/nfs/nfs4proc.c | 26 +++++++++++++++++--------- fs/nfs/nfs4state.c | 15 +++++++++++++++ 3 files changed, 33 insertions(+), 9 deletions(-) (limited to 'fs/nfs') diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h index e9ecd6bf9257..5c7740178a08 100644 --- a/fs/nfs/nfs4_fs.h +++ b/fs/nfs/nfs4_fs.h @@ -45,6 +45,7 @@ enum nfs4_client_state { NFS4CLNT_RECLAIM_NOGRACE, NFS4CLNT_DELEGRETURN, NFS4CLNT_SESSION_RESET, + NFS4CLNT_SESSION_DRAINING, }; /* diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index fb62919f7f2c..c1bc9cad5e85 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -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); diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index f56f6be5e314..3c1433598b60 100644 --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -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) { -- cgit v1.2.3-59-g8ed1b