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/sunrpc/cache.h>
14 #include <linux/sunrpc/rpc_pipe_fs.h>
16 #include "cache_lib.h"
18 #define NFS_CACHE_UPCALL_PATHLEN 256
19 #define NFS_CACHE_UPCALL_TIMEOUT 15
21 static char nfs_cache_getent_prog
[NFS_CACHE_UPCALL_PATHLEN
] =
22 "/sbin/nfs_cache_getent";
23 static unsigned long nfs_cache_getent_timeout
= NFS_CACHE_UPCALL_TIMEOUT
;
25 module_param_string(cache_getent
, nfs_cache_getent_prog
,
26 sizeof(nfs_cache_getent_prog
), 0600);
27 MODULE_PARM_DESC(cache_getent
, "Path to the client cache upcall program");
28 module_param_named(cache_getent_timeout
, nfs_cache_getent_timeout
, ulong
, 0600);
29 MODULE_PARM_DESC(cache_getent_timeout
, "Timeout (in seconds) after which "
30 "the cache upcall is assumed to have failed");
32 int nfs_cache_upcall(struct cache_detail
*cd
, char *entry_name
)
34 static char *envp
[] = { "HOME=/",
36 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
40 nfs_cache_getent_prog
,
47 if (nfs_cache_getent_prog
[0] == '\0')
49 ret
= call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
51 * Disable the upcall mechanism if we're getting an ENOENT or
52 * EACCES error. The admin can re-enable it on the fly by using
53 * sysfs to set the 'cache_getent' parameter once the problem
56 if (ret
== -ENOENT
|| ret
== -EACCES
)
57 nfs_cache_getent_prog
[0] = '\0';
59 return ret
> 0 ? 0 : ret
;
63 * Deferred request handling
65 void nfs_cache_defer_req_put(struct nfs_cache_defer_req
*dreq
)
67 if (atomic_dec_and_test(&dreq
->count
))
71 static void nfs_dns_cache_revisit(struct cache_deferred_req
*d
, int toomany
)
73 struct nfs_cache_defer_req
*dreq
;
75 dreq
= container_of(d
, struct nfs_cache_defer_req
, deferred_req
);
77 complete_all(&dreq
->completion
);
78 nfs_cache_defer_req_put(dreq
);
81 static struct cache_deferred_req
*nfs_dns_cache_defer(struct cache_req
*req
)
83 struct nfs_cache_defer_req
*dreq
;
85 dreq
= container_of(req
, struct nfs_cache_defer_req
, req
);
86 dreq
->deferred_req
.revisit
= nfs_dns_cache_revisit
;
87 atomic_inc(&dreq
->count
);
89 return &dreq
->deferred_req
;
92 struct nfs_cache_defer_req
*nfs_cache_defer_req_alloc(void)
94 struct nfs_cache_defer_req
*dreq
;
96 dreq
= kzalloc(sizeof(*dreq
), GFP_KERNEL
);
98 init_completion(&dreq
->completion
);
99 atomic_set(&dreq
->count
, 1);
100 dreq
->req
.defer
= nfs_dns_cache_defer
;
105 int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req
*dreq
)
107 if (wait_for_completion_timeout(&dreq
->completion
,
108 nfs_cache_getent_timeout
* HZ
) == 0)
113 int nfs_cache_register(struct cache_detail
*cd
)
116 struct vfsmount
*mnt
;
119 mnt
= rpc_get_mount();
122 ret
= vfs_path_lookup(mnt
->mnt_root
, mnt
, "/cache", 0, &nd
);
125 ret
= sunrpc_cache_register_pipefs(nd
.path
.dentry
,
135 void nfs_cache_unregister(struct cache_detail
*cd
)
137 sunrpc_cache_unregister_pipefs(cd
);
This page took 0.032987 seconds and 5 git commands to generate.