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NFS: Use kernel DNS resolver [ver #2] 

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@netapp.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Bryan Schumaker 2010-08-11 09:37:53 +01:00 committed by Steve French
parent 3694b91a59
commit c2e8139c9f
3 changed files with 52 additions and 0 deletions
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16
fs/nfs/Kconfig
View File

@ -100,3 +100,19 @@ config NFS_FSCACHE
help help
Say Y here if you want NFS data to be cached locally on disc through Say Y here if you want NFS data to be cached locally on disc through
the general filesystem cache manager 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

24
fs/nfs/dns_resolve.c
View File

@ -6,6 +6,29 @@
* Resolves DNS hostnames into valid ip addresses * 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/hash.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/kmod.h> #include <linux/kmod.h>
@ -346,3 +369,4 @@ void nfs_dns_resolver_destroy(void)
nfs_cache_unregister(&nfs_dns_resolve); nfs_cache_unregister(&nfs_dns_resolve);
} }
#endif

12
fs/nfs/dns_resolve.h
View File

@ -6,8 +6,20 @@
#define NFS_DNS_HOSTNAME_MAXLEN (128) #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 int nfs_dns_resolver_init(void);
extern void nfs_dns_resolver_destroy(void); extern void nfs_dns_resolver_destroy(void);
#endif
extern ssize_t nfs_dns_resolve_name(char *name, size_t namelen, extern ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
struct sockaddr *sa, size_t salen); struct sockaddr *sa, size_t salen);