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NFSv4: add cl_root_cred for use when machine cred is not available.

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NFSv4 state management tries a root credential when no machine
credential is available, as can happen with kerberos.
It does this by replacing the cl_machine_cred with a root credential.
This means that any user of the machine credential needs to take
a lock while getting a reference to the machine credential, which is
a little cumbersome.

So introduce an explicit cl_root_cred, and never free either
credential until client shutdown.  This means that no locking
is needed to reference these credentials.  Future patches
will make use of this.

This is only a temporary addition.  both cl_machine_cred and
cl_root_cred will disappear later in the series.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
NeilBrown 2018-12-03 11:30:30 +11:00 committed by Anna Schumaker
parent 1a80810fbf
commit a534ecb013
3 changed files with 15 additions and 8 deletions
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2
fs/nfs/client.c
View file

@ -248,6 +248,8 @@ void nfs_free_client(struct nfs_client *clp)
if (clp->cl_machine_cred != NULL)
put_rpccred(clp->cl_machine_cred);
if (clp->cl_root_cred != NULL)
put_rpccred(clp->cl_root_cred);
put_net(clp->cl_net);
put_nfs_version(clp->cl_nfs_mod);

20
fs/nfs/nfs4state.c
View file

@ -166,24 +166,28 @@ int nfs40_discover_server_trunking(struct nfs_client *clp,
struct rpc_cred *nfs4_get_machine_cred_locked(struct nfs_client *clp)
{
struct rpc_cred *cred = NULL;
struct rpc_cred *cred = clp->cl_root_cred;
if (clp->cl_machine_cred != NULL)
cred = get_rpccred(clp->cl_machine_cred);
if (!cred)
cred = clp->cl_machine_cred;
if (cred)
return get_rpccred(cred);
return cred;
}
static void nfs4_root_machine_cred(struct nfs_client *clp)
{
struct rpc_cred *cred, *new;
struct rpc_cred *new;
new = rpc_lookup_machine_cred(NULL);
spin_lock(&clp->cl_lock);
cred = clp->cl_machine_cred;
clp->cl_machine_cred = new;
if (clp->cl_root_cred == NULL) {
clp->cl_root_cred = new;
new = NULL;
}
spin_unlock(&clp->cl_lock);
if (cred != NULL)
put_rpccred(cred);
if (new != NULL)
put_rpccred(new);
}
static struct rpc_cred *

1
include/linux/nfs_fs_sb.h
View file

@ -59,6 +59,7 @@ struct nfs_client {
u32 cl_minorversion;/* NFSv4 minorversion */
struct rpc_cred *cl_machine_cred;
struct rpc_cred *cl_root_cred; /* Use when machine_cred is ineffective */
#if IS_ENABLED(CONFIG_NFS_V4)
struct list_head cl_ds_clients; /* auth flavor data servers */