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
);
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