e571cbf1a4
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. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
140 lines
3.3 KiB
C
140 lines
3.3 KiB
C
/*
|
|
* linux/fs/nfs/cache_lib.c
|
|
*
|
|
* Helper routines for the NFS client caches
|
|
*
|
|
* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
|
|
*/
|
|
#include <linux/kmod.h>
|
|
#include <linux/module.h>
|
|
#include <linux/moduleparam.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/sunrpc/cache.h>
|
|
#include <linux/sunrpc/rpc_pipe_fs.h>
|
|
|
|
#include "cache_lib.h"
|
|
|
|
#define NFS_CACHE_UPCALL_PATHLEN 256
|
|
#define NFS_CACHE_UPCALL_TIMEOUT 15
|
|
|
|
static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] =
|
|
"/sbin/nfs_cache_getent";
|
|
static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT;
|
|
|
|
module_param_string(cache_getent, nfs_cache_getent_prog,
|
|
sizeof(nfs_cache_getent_prog), 0600);
|
|
MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program");
|
|
module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600);
|
|
MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which "
|
|
"the cache upcall is assumed to have failed");
|
|
|
|
int nfs_cache_upcall(struct cache_detail *cd, char *entry_name)
|
|
{
|
|
static char *envp[] = { "HOME=/",
|
|
"TERM=linux",
|
|
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
|
|
NULL
|
|
};
|
|
char *argv[] = {
|
|
nfs_cache_getent_prog,
|
|
cd->name,
|
|
entry_name,
|
|
NULL
|
|
};
|
|
int ret = -EACCES;
|
|
|
|
if (nfs_cache_getent_prog[0] == '\0')
|
|
goto out;
|
|
ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
|
/*
|
|
* Disable the upcall mechanism if we're getting an ENOENT or
|
|
* EACCES error. The admin can re-enable it on the fly by using
|
|
* sysfs to set the 'cache_getent' parameter once the problem
|
|
* has been fixed.
|
|
*/
|
|
if (ret == -ENOENT || ret == -EACCES)
|
|
nfs_cache_getent_prog[0] = '\0';
|
|
out:
|
|
return ret > 0 ? 0 : ret;
|
|
}
|
|
|
|
/*
|
|
* Deferred request handling
|
|
*/
|
|
void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq)
|
|
{
|
|
if (atomic_dec_and_test(&dreq->count))
|
|
kfree(dreq);
|
|
}
|
|
|
|
static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany)
|
|
{
|
|
struct nfs_cache_defer_req *dreq;
|
|
|
|
dreq = container_of(d, struct nfs_cache_defer_req, deferred_req);
|
|
|
|
complete_all(&dreq->completion);
|
|
nfs_cache_defer_req_put(dreq);
|
|
}
|
|
|
|
static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req)
|
|
{
|
|
struct nfs_cache_defer_req *dreq;
|
|
|
|
dreq = container_of(req, struct nfs_cache_defer_req, req);
|
|
dreq->deferred_req.revisit = nfs_dns_cache_revisit;
|
|
atomic_inc(&dreq->count);
|
|
|
|
return &dreq->deferred_req;
|
|
}
|
|
|
|
struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void)
|
|
{
|
|
struct nfs_cache_defer_req *dreq;
|
|
|
|
dreq = kzalloc(sizeof(*dreq), GFP_KERNEL);
|
|
if (dreq) {
|
|
init_completion(&dreq->completion);
|
|
atomic_set(&dreq->count, 1);
|
|
dreq->req.defer = nfs_dns_cache_defer;
|
|
}
|
|
return dreq;
|
|
}
|
|
|
|
int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
|
|
{
|
|
if (wait_for_completion_timeout(&dreq->completion,
|
|
nfs_cache_getent_timeout * HZ) == 0)
|
|
return -ETIMEDOUT;
|
|
return 0;
|
|
}
|
|
|
|
int nfs_cache_register(struct cache_detail *cd)
|
|
{
|
|
struct nameidata nd;
|
|
struct vfsmount *mnt;
|
|
int ret;
|
|
|
|
mnt = rpc_get_mount();
|
|
if (IS_ERR(mnt))
|
|
return PTR_ERR(mnt);
|
|
ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &nd);
|
|
if (ret)
|
|
goto err;
|
|
ret = sunrpc_cache_register_pipefs(nd.path.dentry,
|
|
cd->name, 0600, cd);
|
|
path_put(&nd.path);
|
|
if (!ret)
|
|
return ret;
|
|
err:
|
|
rpc_put_mount();
|
|
return ret;
|
|
}
|
|
|
|
void nfs_cache_unregister(struct cache_detail *cd)
|
|
{
|
|
sunrpc_cache_unregister_pipefs(cd);
|
|
rpc_put_mount();
|
|
}
|
|
|