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authorTrond Myklebust <Trond.Myklebust@netapp.com>2011-08-02 14:46:29 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2011-08-04 11:55:35 -0400
commit55a673990ec04cf63005318bcf08c2b0046e5778 (patch)
tree71e4fb3292060553063042c6190031d104d9c1f5 /fs/nfs/callback_xdr.c
parent9af7db3228acc286c50e3a0f054ec982efdbc6c6 (diff)
downloadop-kernel-dev-55a673990ec04cf63005318bcf08c2b0046e5778.zip
op-kernel-dev-55a673990ec04cf63005318bcf08c2b0046e5778.tar.gz
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 <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/callback_xdr.c')
-rw-r--r--fs/nfs/callback_xdr.c24
1 files changed, 7 insertions, 17 deletions
diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index c6c86a7..918ad64 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;
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