Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / fs / nfs / cache_lib.c

diff --git a/kernel/fs/nfs/cache_lib.c b/kernel/fs/nfs/cache_lib.c
new file mode 100644 (file)
index 0000000..5f7b053
--- /dev/null
+++ b/kernel/fs/nfs/cache_lib.c
@@ -0,0 +1,158 @@
+/*
+ * 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");
+       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 super_block *pipefs_sb;
+       int ret = 0;
+
+       sunrpc_init_cache_detail(cd);
+       pipefs_sb = rpc_get_sb_net(net);
+       if (pipefs_sb) {
+               ret = nfs_cache_register_sb(pipefs_sb, cd);
+               rpc_put_sb_net(net);
+               if (ret)
+                       sunrpc_destroy_cache_detail(cd);
+       }
+       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);
+       }
+       sunrpc_destroy_cache_detail(cd);
+}