mirror of
https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
![Stanislav Kinsbursky](/assets/img/avatar_default.png)
This patch subscribes DNS resolver caches to RPC pipefs notifications. Notifier is registering on NFS module load. This notifier callback is responsible for creation/destruction of PipeFS DNS resolver cache directory. Note that no locking required in notifier callback because PipeFS superblock pointer is passed as an argument from it's creation or destruction routine and thus we can be sure about it's validity. Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
177 lines
4.1 KiB
C
177 lines
4.1 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/slab.h>
|
|
#include <linux/sunrpc/cache.h>
|
|
#include <linux/sunrpc/rpc_pipe_fs.h>
|
|
#include <net/net_namespace.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_sb(struct super_block *sb, struct cache_detail *cd)
|
|
{
|
|
int ret;
|
|
struct dentry *dir;
|
|
|
|
dir = rpc_d_lookup_sb(sb, "cache");
|
|
BUG_ON(dir == NULL);
|
|
ret = sunrpc_cache_register_pipefs(dir, cd->name, 0600, cd);
|
|
dput(dir);
|
|
return ret;
|
|
}
|
|
|
|
int nfs_cache_register_net(struct net *net, struct cache_detail *cd)
|
|
{
|
|
struct vfsmount *mnt;
|
|
struct super_block *pipefs_sb;
|
|
int ret;
|
|
|
|
mnt = rpc_get_mount();
|
|
if (IS_ERR(mnt))
|
|
return PTR_ERR(mnt);
|
|
pipefs_sb = rpc_get_sb_net(net);
|
|
if (!pipefs_sb) {
|
|
ret = -ENOENT;
|
|
goto err;
|
|
}
|
|
ret = nfs_cache_register_sb(pipefs_sb, cd);
|
|
rpc_put_sb_net(net);
|
|
if (!ret)
|
|
return ret;
|
|
err:
|
|
rpc_put_mount();
|
|
return ret;
|
|
}
|
|
|
|
void nfs_cache_unregister_sb(struct super_block *sb, struct cache_detail *cd)
|
|
{
|
|
if (cd->u.pipefs.dir)
|
|
sunrpc_cache_unregister_pipefs(cd);
|
|
}
|
|
|
|
void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd)
|
|
{
|
|
struct super_block *pipefs_sb;
|
|
|
|
pipefs_sb = rpc_get_sb_net(net);
|
|
if (pipefs_sb) {
|
|
nfs_cache_unregister_sb(pipefs_sb, cd);
|
|
rpc_put_sb_net(net);
|
|
}
|
|
rpc_put_mount();
|
|
}
|
|
|
|
void nfs_cache_init(struct cache_detail *cd)
|
|
{
|
|
sunrpc_init_cache_detail(cd);
|
|
}
|
|
|
|
void nfs_cache_destroy(struct cache_detail *cd)
|
|
{
|
|
sunrpc_destroy_cache_detail(cd);
|
|
}
|