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NFSv4.1: Fix the callback 'highest_used_slotid' behaviour

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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 <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2011-08-02 14:46:29 -04:00
parent 9af7db3228
commit 55a673990e
3 changed files with 22 additions and 24 deletions
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2
fs/nfs/callback.h
View file

@ -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;

20
fs/nfs/callback_proc.c
View file

@ -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 */

24
fs/nfs/callback_xdr.c
View file

@ -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;