From 55a673990ec04cf63005318bcf08c2b0046e5778 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 2 Aug 2011 14:46:29 -0400 Subject: NFSv4.1: Fix the callback 'highest_used_slotid' behaviour Currently, there is no guarantee that we will call nfs4_cb_take_slot() even though nfs4_callback_compound() will consistently call nfs4_cb_free_slot() provided the cb_process_state has set the 'clp' field. The result is that we can trigger the BUG_ON() upon the next call to nfs4_cb_take_slot(). This patch fixes the above problem by using the slot id that was taken in the CB_SEQUENCE operation as a flag for whether or not we need to call nfs4_cb_free_slot(). It also fixes an atomicity problem: we need to set tbl->highest_used_slotid atomically with the check for NFS4_SESSION_DRAINING, otherwise we end up racing with the various tests in nfs4_begin_drain_session(). Cc: stable@kernel.org [2.6.38+] Signed-off-by: Trond Myklebust --- fs/nfs/callback.h | 2 +- fs/nfs/callback_proc.c | 20 ++++++++++++++------ fs/nfs/callback_xdr.c | 24 +++++++----------------- 3 files changed, 22 insertions(+), 24 deletions(-) (limited to 'fs/nfs') diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h index b257383bb565..07df5f1d85e5 100644 --- a/fs/nfs/callback.h +++ b/fs/nfs/callback.h @@ -38,6 +38,7 @@ enum nfs4_callback_opnum { struct cb_process_state { __be32 drc_status; struct nfs_client *clp; + int slotid; }; struct cb_compound_hdr_arg { @@ -166,7 +167,6 @@ extern unsigned nfs4_callback_layoutrecall( void *dummy, struct cb_process_state *cps); extern void nfs4_check_drain_bc_complete(struct nfs4_session *ses); -extern void nfs4_cb_take_slot(struct nfs_client *clp); struct cb_devicenotifyitem { uint32_t cbd_notify_type; diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c index 74780f9f852c..0ab82020f5db 100644 --- a/fs/nfs/callback_proc.c +++ b/fs/nfs/callback_proc.c @@ -348,7 +348,7 @@ validate_seqid(struct nfs4_slot_table *tbl, struct cb_sequenceargs * args) /* Normal */ if (likely(args->csa_sequenceid == slot->seq_nr + 1)) { slot->seq_nr++; - return htonl(NFS4_OK); + goto out_ok; } /* Replay */ @@ -367,11 +367,14 @@ validate_seqid(struct nfs4_slot_table *tbl, struct cb_sequenceargs * args) /* Wraparound */ if (args->csa_sequenceid == 1 && (slot->seq_nr + 1) == 0) { slot->seq_nr = 1; - return htonl(NFS4_OK); + goto out_ok; } /* Misordered request */ return htonl(NFS4ERR_SEQ_MISORDERED); +out_ok: + tbl->highest_used_slotid = args->csa_slotid; + return htonl(NFS4_OK); } /* @@ -433,26 +436,32 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args, struct cb_sequenceres *res, struct cb_process_state *cps) { + struct nfs4_slot_table *tbl; struct nfs_client *clp; int i; __be32 status = htonl(NFS4ERR_BADSESSION); - cps->clp = NULL; - clp = nfs4_find_client_sessionid(args->csa_addr, &args->csa_sessionid); if (clp == NULL) goto out; + tbl = &clp->cl_session->bc_slot_table; + + spin_lock(&tbl->slot_tbl_lock); /* state manager is resetting the session */ if (test_bit(NFS4_SESSION_DRAINING, &clp->cl_session->session_state)) { - status = NFS4ERR_DELAY; + spin_unlock(&tbl->slot_tbl_lock); + status = htonl(NFS4ERR_DELAY); goto out; } status = validate_seqid(&clp->cl_session->bc_slot_table, args); + spin_unlock(&tbl->slot_tbl_lock); if (status) goto out; + cps->slotid = args->csa_slotid; + /* * Check for pending referring calls. If a match is found, a * related callback was received before the response to the original @@ -469,7 +478,6 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args, res->csr_slotid = args->csa_slotid; res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1; res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1; - nfs4_cb_take_slot(clp); out: cps->clp = clp; /* put in nfs4_callback_compound */ diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c index c6c86a77e043..918ad647afea 100644 --- a/fs/nfs/callback_xdr.c +++ b/fs/nfs/callback_xdr.c @@ -754,26 +754,15 @@ static void nfs4_callback_free_slot(struct nfs4_session *session) * Let the state manager know callback processing done. * A single slot, so highest used slotid is either 0 or -1 */ - tbl->highest_used_slotid--; + tbl->highest_used_slotid = -1; nfs4_check_drain_bc_complete(session); spin_unlock(&tbl->slot_tbl_lock); } -static void nfs4_cb_free_slot(struct nfs_client *clp) +static void nfs4_cb_free_slot(struct cb_process_state *cps) { - if (clp && clp->cl_session) - nfs4_callback_free_slot(clp->cl_session); -} - -/* A single slot, so highest used slotid is either 0 or -1 */ -void nfs4_cb_take_slot(struct nfs_client *clp) -{ - struct nfs4_slot_table *tbl = &clp->cl_session->bc_slot_table; - - spin_lock(&tbl->slot_tbl_lock); - tbl->highest_used_slotid++; - BUG_ON(tbl->highest_used_slotid != 0); - spin_unlock(&tbl->slot_tbl_lock); + if (cps->slotid != -1) + nfs4_callback_free_slot(cps->clp->cl_session); } #else /* CONFIG_NFS_V4_1 */ @@ -784,7 +773,7 @@ preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op) return htonl(NFS4ERR_MINOR_VERS_MISMATCH); } -static void nfs4_cb_free_slot(struct nfs_client *clp) +static void nfs4_cb_free_slot(struct cb_process_state *cps) { } #endif /* CONFIG_NFS_V4_1 */ @@ -866,6 +855,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r struct cb_process_state cps = { .drc_status = 0, .clp = NULL, + .slotid = -1, }; unsigned int nops = 0; @@ -906,7 +896,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r *hdr_res.status = status; *hdr_res.nops = htonl(nops); - nfs4_cb_free_slot(cps.clp); + nfs4_cb_free_slot(&cps); nfs_put_client(cps.clp); dprintk("%s: done, status = %u\n", __func__, ntohl(status)); return rpc_success; -- cgit v1.2.3