On Wed, 5 Mar 2014 09:43:03 -0500 Trond Myklebust
<trond.myklebust@xxxxxxxxxxxxxxx> wrote:
>
> On Mar 4, 2014, at 22:00, NeilBrown <neilb@xxxxxxx> wrote:
>
> > This arg causes rpc_lookup_cred to set RPCAUTH_LOOKUP_RCU when
> > performing the credential lookup. Most callers pass '0',
> > except nfs_permission() which passes (mask & MAY_NOT_BLOCK).
> >
>
> Why not just add a function rpc_lookup_cred_rcu() or rpc_lookup_cred_noblock() to cater for that one exception?
That certainly makes the patch smaller, and is probably a net win.
Thanks.
NeilBrown
From b805a8f79a5527676b96b9654dd26d1b5bc03691 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxx>
Date: Tue, 4 Mar 2014 15:28:43 +1100
Subject: [PATCH] sunrpc/auth: add rpc_lookup_cred_nonblock
This version of rpc_lookup_cred sets RPCAUTH_LOOKUP_RCU when
performing the credential lookup.
nfs_permission() uses it in RCU-walk mode.
This doesn't speed up nfs_permission yet as it is not yet
safe to call nfs_do_access with the returned cred.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 7530acdc5c42..ede873e88acc 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2318,10 +2318,12 @@ force_lookup:
goto out_notsup;
if (mask & MAY_NOT_BLOCK)
- return -ECHILD;
-
- cred = rpc_lookup_cred();
+ cred = rpc_lookup_cred_nonblock();
+ else
+ cred = rpc_lookup_cred();
if (!IS_ERR(cred)) {
+ if (mask & MAY_NOT_BLOCK)
+ return -ECHILD;
res = nfs_do_access(inode, cred, mask);
put_rpccred(cred);
} else
diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 3f158ae1d6fd..28ffc8476875 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -154,6 +154,7 @@ void rpc_destroy_generic_auth(void);
void rpc_destroy_authunix(void);
struct rpc_cred * rpc_lookup_cred(void);
+struct rpc_cred * rpc_lookup_cred_nonblock(void);
struct rpc_cred * rpc_lookup_machine_cred(const char *service_name);
int rpcauth_register(const struct rpc_authops *);
int rpcauth_unregister(const struct rpc_authops *);
diff --git a/net/sunrpc/auth_generic.c b/net/sunrpc/auth_generic.c
index ed04869b2d4f..632f6eec8111 100644
--- a/net/sunrpc/auth_generic.c
+++ b/net/sunrpc/auth_generic.c
@@ -38,6 +38,11 @@ struct rpc_cred *rpc_lookup_cred(void)
}
EXPORT_SYMBOL_GPL(rpc_lookup_cred);
+struct rpc_cred *rpc_lookup_cred_nonblock(void)
+{
+ return rpcauth_lookupcred(&generic_auth, 1);
+}
+
/*
* Public call interface for looking up machine creds.
*/
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