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From: David Howells on 11 Aug 2010 04:40
From: Bryan Schumaker <bjschuma(a)netapp.com>

Use the kernel DNS resolver to translate hostnames to IP addresses. Create a
new config option to choose between the legacy DNS resolver and the new
resolver.

Signed-off-by: Bryan Schumaker <bjschuma(a)netapp.com>
Acked-by: Trond Myklebust <Trond.Myklebust(a)netapp.com>
Signed-off-by: David Howells <dhowells(a)redhat.com>
---

fs/nfs/Kconfig | 16 ++++++++++++++++
fs/nfs/dns_resolve.c | 24 ++++++++++++++++++++++++
fs/nfs/dns_resolve.h | 12 ++++++++++++
3 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index cc1bb33..c5bbdca 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -100,3 +100,19 @@ 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_USE_LEGACY_DNS
+ bool "Use the legacy NFS DNS resolver"
+ depends on NFS_V4
+ help
+ The kernel now provides a method for translating a host name into an
+ IP address. Select Y here if you would rather use your own DNS
+ resolver script.
+
+ If unsure, say N
+
+config NFS_USE_KERNEL_DNS
+ bool
+ depends on NFS_V4 && !NFS_USE_LEGACY_DNS
+ select DNS_RESOLVER
+ default y
diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index 76fd235..dba50a5 100644
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -6,6 +6,29 @@
* Resolves DNS hostnames into valid ip addresses
*/

+#ifdef CONFIG_NFS_USE_KERNEL_DNS
+
+#include <linux/sunrpc/clnt.h>
+#include <linux/dns_resolver.h>
+
+ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
+ struct sockaddr *sa, size_t salen)
+{
+ ssize_t ret;
+ char *ip_addr = NULL;
+ int ip_len;
+
+ ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
+ if (ip_len > 0)
+ ret = rpc_pton(ip_addr, ip_len, sa, salen);
+ else
+ ret = -ESRCH;
+ kfree(ip_addr);
+ return ret;
+}
+
+#else
+
#include <linux/hash.h>
#include <linux/string.h>
#include <linux/kmod.h>
@@ -346,3 +369,4 @@ void nfs_dns_resolver_destroy(void)
nfs_cache_unregister(&nfs_dns_resolve);
}

+#endif
diff --git a/fs/nfs/dns_resolve.h b/fs/nfs/dns_resolve.h
index a3f0938..199bb55 100644
--- a/fs/nfs/dns_resolve.h
+++ b/fs/nfs/dns_resolve.h
@@ -6,8 +6,20 @@

#define NFS_DNS_HOSTNAME_MAXLEN (128)

+
+#ifdef CONFIG_NFS_USE_KERNEL_DNS
+static inline int nfs_dns_resolver_init(void)
+{
+ return 0;
+}
+
+static inline void nfs_dns_resolver_destroy(void)
+{}
+#else
extern int nfs_dns_resolver_init(void);
extern void nfs_dns_resolver_destroy(void);
+#endif
+
extern ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
struct sockaddr *sa, size_t salen);


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Prev: [PATCH] staging: adis16255: fix sysfs leak
Next: [PATCH 3/3] AFS: Implement an autocell mount capability [ver #2]