2 * linux/fs/nfs/cache_lib.c
4 * Helper routines for the NFS client caches
6 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
8 #include <linux/kmod.h>
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/mount.h>
12 #include <linux/namei.h>
13 #include <linux/slab.h>
14 #include <linux/sunrpc/cache.h>
15 #include <linux/sunrpc/rpc_pipe_fs.h>
16 #include <net/net_namespace.h>
18 #include "cache_lib.h"
20 #define NFS_CACHE_UPCALL_PATHLEN 256
21 #define NFS_CACHE_UPCALL_TIMEOUT 15
23 static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] =
24 "/sbin/nfs_cache_getent";
25 static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT;
27 module_param_string(cache_getent, nfs_cache_getent_prog,
28 sizeof(nfs_cache_getent_prog), 0600);
29 MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program");
30 module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600);
31 MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which "
32 "the cache upcall is assumed to have failed");
34 int nfs_cache_upcall(struct cache_detail *cd, char *entry_name)
36 static char *envp[] = { "HOME=/",
38 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
42 nfs_cache_getent_prog,
49 if (nfs_cache_getent_prog[0] == '\0')
51 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
53 * Disable the upcall mechanism if we're getting an ENOENT or
54 * EACCES error. The admin can re-enable it on the fly by using
55 * sysfs to set the 'cache_getent' parameter once the problem
58 if (ret == -ENOENT || ret == -EACCES)
59 nfs_cache_getent_prog[0] = '\0';
61 return ret > 0 ? 0 : ret;
65 * Deferred request handling
67 void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq)
69 if (atomic_dec_and_test(&dreq->count))
73 static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany)
75 struct nfs_cache_defer_req *dreq;
77 dreq = container_of(d, struct nfs_cache_defer_req, deferred_req);
79 complete_all(&dreq->completion);
80 nfs_cache_defer_req_put(dreq);
83 static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req)
85 struct nfs_cache_defer_req *dreq;
87 dreq = container_of(req, struct nfs_cache_defer_req, req);
88 dreq->deferred_req.revisit = nfs_dns_cache_revisit;
89 atomic_inc(&dreq->count);
91 return &dreq->deferred_req;
94 struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void)
96 struct nfs_cache_defer_req *dreq;
98 dreq = kzalloc(sizeof(*dreq), GFP_KERNEL);
100 init_completion(&dreq->completion);
101 atomic_set(&dreq->count, 1);
102 dreq->req.defer = nfs_dns_cache_defer;
107 int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
109 if (wait_for_completion_timeout(&dreq->completion,
110 nfs_cache_getent_timeout * HZ) == 0)
115 int nfs_cache_register_sb(struct super_block *sb, struct cache_detail *cd)
120 dir = rpc_d_lookup_sb(sb, "cache");
121 ret = sunrpc_cache_register_pipefs(dir, cd->name, 0600, cd);
126 int nfs_cache_register_net(struct net *net, struct cache_detail *cd)
128 struct super_block *pipefs_sb;
131 sunrpc_init_cache_detail(cd);
132 pipefs_sb = rpc_get_sb_net(net);
134 ret = nfs_cache_register_sb(pipefs_sb, cd);
137 sunrpc_destroy_cache_detail(cd);
142 void nfs_cache_unregister_sb(struct super_block *sb, struct cache_detail *cd)
144 if (cd->u.pipefs.dir)
145 sunrpc_cache_unregister_pipefs(cd);
148 void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd)
150 struct super_block *pipefs_sb;
152 pipefs_sb = rpc_get_sb_net(net);
154 nfs_cache_unregister_sb(pipefs_sb, cd);
157 sunrpc_destroy_cache_detail(cd);