Re: [PATCH 30/32] NFS: Add a dns resolver for use with NFSv4 referrals and migration

Chuck Lever <chuck.lever@xxxxxxxxxx> · Fri, 21 Aug 2009 16:57:02 -0400

On Aug 21, 2009, at 4:47 PM, J. Bruce Fields wrote:
On Wed, Aug 19, 2009 at 07:51:56PM -0400, Trond Myklebust wrote:
On Wed, 2009-08-19 at 19:38 -0400, Trond Myklebust wrote:
The NFSv4 and NFSv4.1 protocols both allow for the redirection of  
a client
from one server to another in order to support filesystem  
migration and
replication. For full protocol support, we need to add the ability  
to
convert a DNS host name into an IP address that we can feed to the  
RPC
client.

We'll reuse the sunrpc cache, now that it has been converted to  
work with
rpc_pipefs.

Should I merge this too?

It's cute.  If it's expected that more people may want to write
nfs_cache_getent scripts, maybe it would be useful to them.  But then,
it's not that hard for them just to call the script by hand.

I guess I probably wouldn't....

I like the idea of including test code, but this looks like it would  
almost never be run.  If the tests were run automatically somehow, it  
might be worth adding.


--b.


From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Subject: NFS: Testcase for the DNS resolver

Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---

fs/nfs/Kconfig           |   11 ++++++++++
fs/nfs/Makefile          |    4 +++
fs/nfs/cache_testcases.c |   53 ++++++++++++++++++++++++++++++++++++ 
++++++++++
fs/nfs/dns_resolve.c     |    1 +
4 files changed, 69 insertions(+), 0 deletions(-)
create mode 100644 fs/nfs/cache_testcases.c

diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 2a77bc2..13fc471 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -101,3 +101,14 @@ config NFS_FSCACHE
	help
	  Say Y here if you want NFS data to be cached locally on disc  
through
	  the general filesystem cache manager
+
+config NFS_CACHETEST
+	tristate "Test the NFS client DNS cache upcalls"
+	depends on NFS_FS
+	default N
+	help
+	  Choose M if you want to build a module that can be used to test
+	  the NFS client DNS cache upcall mechanism.
+
+	  Most people will want to say N
+
diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index da7fda6..4fe5ac2 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -17,3 +17,7 @@ nfs-$(CONFIG_NFS_V4)	+= nfs4proc.o nfs4xdr.o  
nfs4state.o nfs4renewd.o \
			   nfs4namespace.o
nfs-$(CONFIG_SYSCTL) += sysctl.o
nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o
+
+obj-$(CONFIG_NFS_CACHETEST) += nfs_cachetest.o
+nfs_cachetest-objs := cache_testcases.o
+
diff --git a/fs/nfs/cache_testcases.c b/fs/nfs/cache_testcases.c
new file mode 100644
index 0000000..2d8810a
--- /dev/null
+++ b/fs/nfs/cache_testcases.c
@@ -0,0 +1,53 @@
+/*
+ * linux/fs/nfs/cache_testcases.c
+ *
+ * Testcases for the NFS client cache upcalls
+ *
+ * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/sunrpc/clnt.h>
+
+#include "dns_resolve.h"
+
+static char hostname[NFS_DNS_HOSTNAME_MAXLEN] = "";
+module_param_string(hostname, hostname, sizeof(hostname), 0600);
+MODULE_PARM_DESC(hostname, "DNS hostname to look up");
+
+static int nfs_lookup_hostname(char *name)
+{
+	struct sockaddr_storage sa;
+	ssize_t salen;
+
+	if (!name || *name == '\0')
+		goto out;
+	salen = nfs_dns_resolve_name(name, strlen(name),
+			(struct sockaddr *)&sa, sizeof(sa));
+	if (salen > 0) {
+		char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
+
+		rpc_ntop((struct sockaddr *)&sa, buf, sizeof(buf));
+		printk(KERN_NOTICE "%15s ", buf);
+	} else
+		printk(KERN_NOTICE "%15zd ", salen);
+	printk("%15s\n", name);
+out:
+	return 0;
+}
+
+static int nfs_dnstest_init(void)
+{
+	return nfs_lookup_hostname(hostname);
+}
+
+static void nfs_dnstest_exit(void)
+{
+}
+
+MODULE_AUTHOR("Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+
+module_init(nfs_dnstest_init)
+module_exit(nfs_dnstest_exit)
diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index f4d54ba..572d453 100644
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -322,6 +322,7 @@ ssize_t nfs_dns_resolve_name(char *name, size_t  
namelen,
		ret = -ESRCH;
	return ret;
}
+EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);

int nfs_dns_resolver_init(void)
{

--
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com



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