diff -Nurp a/fs/nfs/Makefile b/fs/nfs/Makefile
--- a/fs/nfs/Makefile	2006-04-23 17:35:59.000000000 +0200
+++ b/fs/nfs/Makefile	2006-04-23 23:31:21.000000000 +0200
@@ -14,4 +14,5 @@ nfs-$(CONFIG_NFS_V4)	+= nfs4proc.o nfs4x
 			   callback.o callback_xdr.o callback_proc.o
 nfs-$(CONFIG_NFS_DIRECTIO) += direct.o
 nfs-$(CONFIG_SYSCTL) += sysctl.o
+nfs-$(CONFIG_SYSCTL)	+= sysctl_net_nfs.o
 nfs-objs		:= $(nfs-y)
diff -Nurp a/fs/nfs/dir.c b/fs/nfs/dir.c
--- a/fs/nfs/dir.c	2006-04-23 17:35:59.000000000 +0200
+++ b/fs/nfs/dir.c	2006-04-23 23:25:27.000000000 +0200
@@ -609,6 +609,8 @@ int nfs_fsync_dir(struct file *filp, str
  */
 static inline int nfs_check_verifier(struct inode *dir, struct dentry *dentry)
 {
+	if (NFS_NOAC_TIMEOUT(dir))
+		return 0;
 	if (IS_ROOT(dentry))
 		return 1;
 	if ((NFS_I(dir)->cache_validity & NFS_INO_INVALID_ATTR) != 0
diff -Nurp a/fs/nfs/inode.c b/fs/nfs/inode.c
--- a/fs/nfs/inode.c	2006-04-23 17:35:59.000000000 +0200
+++ b/fs/nfs/inode.c	2006-04-23 23:25:27.000000000 +0200
@@ -660,7 +660,8 @@ static void nfs_zap_caches_locked(struct
 	struct nfs_inode *nfsi = NFS_I(inode);
 	int mode = inode->i_mode;
 
-	NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
+	if (!NFS_NOAC_TIMEOUT(inode))
+		NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
 	NFS_ATTRTIMEO_UPDATE(inode) = jiffies;
 
 	memset(NFS_COOKIEVERF(inode), 0, sizeof(NFS_COOKIEVERF(inode)));
@@ -819,6 +820,7 @@ nfs_fhget(struct super_block *sb, struct
 		}
 		nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
 		nfsi->attrtimeo_timestamp = jiffies;
+		nfsi->noac_timeout = 0;
 		memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
 		nfsi->cache_access.cred = NULL;
 
@@ -1519,6 +1521,16 @@ static int nfs_update_inode(struct inode
  		inode->i_blksize = fattr->du.nfs2.blocksize;
  	}
 
+	/* check for attribute cache reactivation */
+	if (  NFS_NOAC_TIMEOUT(inode)
+	   && NFS_ATTRTIMEO(inode) == 0
+	   && time_after(jiffies, NFS_NOAC_TIMEOUT(inode))
+	   )
+	{
+		NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
+		NFS_NOAC_TIMEOUT(inode) = 0;
+	}
+
 	/* Update attrtimeo value if we're out of the unstable period */
 	if (invalid & NFS_INO_INVALID_ATTR) {
 		nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
@@ -2209,6 +2221,9 @@ static int __init init_nfs_fs(void)
 #ifdef CONFIG_PROC_FS
 	rpc_proc_register(&nfs_rpcstat);
 #endif
+#ifdef CONFIG_SYSCTL
+	nfs_sysctl_register();
+#endif
         err = register_filesystem(&nfs_fs_type);
 	if (err)
 		goto out;
@@ -2216,6 +2231,9 @@ static int __init init_nfs_fs(void)
 		goto out;
 	return 0;
 out:
+#ifdef CONFIG_SYSCTL
+	nfs_sysctl_unregister();
+#endif
 #ifdef CONFIG_PROC_FS
 	rpc_proc_unregister("nfs");
 #endif
@@ -2246,6 +2264,9 @@ static void __exit exit_nfs_fs(void)
 #ifdef CONFIG_PROC_FS
 	rpc_proc_unregister("nfs");
 #endif
+#ifdef CONFIG_SYSCTL
+	nfs_sysctl_unregister();
+#endif
 	unregister_filesystem(&nfs_fs_type);
 	unregister_nfs4fs();
 }
diff -Nurp a/fs/nfs/sysctl_net_nfs.c b/fs/nfs/sysctl_net_nfs.c
--- a/fs/nfs/sysctl_net_nfs.c	1970-01-01 01:00:00.000000000 +0100
+++ b/fs/nfs/sysctl_net_nfs.c	2006-04-23 23:25:27.000000000 +0200
@@ -0,0 +1,93 @@
+/*
+ * Sysctl interface to NFS.
+ *
+ * Authors:	Frank van Maarseveen
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ *
+ * /proc/sys/net/nfs/noac-timeout
+ * When a nonzero value is written, suspend atribute caching for the current
+ * working directory and one level of files inside for the specified number
+ * of seconds. Attribute caching will automatically be enabled when the time
+ * elapses. Writing a zero re-enables attribute caching as well. Reading
+ * yields the number of remaining seconds attribute caching will be disabled.
+ *
+ * Notes:
+ * -	sys_sysctl() not supported, only /proc/sys
+ */
+
+#include <linux/mm.h>
+#include <linux/sysctl.h>
+#include <linux/nfs_fs.h>
+
+static	int				sysctl_noac_timeout;	/* not used */
+static	struct ctl_table_header *	nfs_sysctl_header;
+
+static int proc_noac_timeout(ctl_table *table, int write, struct file *filp,
+		     void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int			noac_timeout, error;
+	struct inode		*inode;
+	struct ctl_table	ctl;
+
+	inode = current->fs->pwd->d_inode;
+	if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
+		return -ENOSYS;
+
+	ctl = *table;
+	ctl.data = &noac_timeout;
+
+	/* check for attribute cache reactivation */
+	if (  NFS_NOAC_TIMEOUT(inode)
+	   && NFS_ATTRTIMEO(inode) == 0
+	   && time_after(jiffies, NFS_NOAC_TIMEOUT(inode))
+	   )
+	{
+		NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
+		NFS_NOAC_TIMEOUT(inode) = 0;
+	}
+
+	noac_timeout = NFS_NOAC_TIMEOUT(inode);
+	if (noac_timeout)
+		noac_timeout -= jiffies;
+	error = proc_dointvec_jiffies(&ctl, write, filp, buffer, lenp, ppos);
+	if (write && !error) {
+		if (noac_timeout) {
+			NFS_NOAC_TIMEOUT(inode) = jiffies + noac_timeout;
+			NFS_ATTRTIMEO(inode) = 0;
+		} else {
+			NFS_NOAC_TIMEOUT(inode) = 0;
+			NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
+		}
+	}
+	return error;
+}
+
+static ctl_table nfs_table[] = {
+	{NET_NFS_NOAC_TIMEOUT, "noac-timeout", &sysctl_noac_timeout, sizeof(int), 0666, NULL, &proc_noac_timeout},
+	{0}
+};
+
+static ctl_table nfs_net_table[] = {
+	{NET_NFS, "nfs", NULL, 0, 0555, nfs_table},
+	{0}
+};
+
+static ctl_table nfs_root_table[] = {
+	{CTL_NET, "net", NULL, 0, 0555, nfs_net_table},
+	{0}
+};
+
+void nfs_sysctl_register(void)
+{
+	nfs_sysctl_header = register_sysctl_table(nfs_root_table, 0);
+}
+
+void nfs_sysctl_unregister(void)
+{
+	unregister_sysctl_table(nfs_sysctl_header);
+}
diff -Nurp a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
--- a/include/linux/nfs_fs.h	2006-04-23 17:36:04.000000000 +0200
+++ b/include/linux/nfs_fs.h	2006-04-23 23:25:27.000000000 +0200
@@ -139,6 +139,13 @@ struct nfs_inode {
 	unsigned long		attrtimeo_timestamp;
 	__u64			change_attr;		/* v4 only */
 
+	/*
+	 * attribute caching can selectively be suspended by clearing
+	 * attrtimeo. When jiffies > noac_timeout then attribute
+	 * caching will be reactivated.
+	 */
+	unsigned long		noac_timeout;
+
 	unsigned long		last_updated;
 	/* "Generation counter" for the attribute cache. This is
 	 * bumped whenever we update the metadata on the
@@ -221,6 +228,7 @@ static inline struct nfs_inode *NFS_I(st
 #define NFS_READTIME(inode)		(NFS_I(inode)->read_cache_jiffies)
 #define NFS_CHANGE_ATTR(inode)		(NFS_I(inode)->change_attr)
 #define NFS_ATTRTIMEO(inode)		(NFS_I(inode)->attrtimeo)
+#define NFS_NOAC_TIMEOUT(inode)		(NFS_I(inode)->noac_timeout)
 #define NFS_MINATTRTIMEO(inode) \
 	(S_ISDIR(inode->i_mode)? NFS_SERVER(inode)->acdirmin \
 			       : NFS_SERVER(inode)->acregmin)
@@ -318,6 +326,12 @@ extern void nfs_file_set_open_context(st
 extern struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, int mode);
 extern void nfs_file_clear_open_context(struct file *filp);
 
+/*
+ * linux/fs/nfs/sysctl_net_nfs.c
+ */
+extern void nfs_sysctl_register(void);
+extern void nfs_sysctl_unregister(void);
+
 /* linux/net/ipv4/ipconfig.c: trims ip addr off front of name, too. */
 extern u32 root_nfs_parse_addr(char *name); /*__init*/
 
diff -Nurp a/include/linux/sysctl.h b/include/linux/sysctl.h
--- a/include/linux/sysctl.h	2006-04-23 17:36:04.000000000 +0200
+++ b/include/linux/sysctl.h	2006-04-23 23:25:27.000000000 +0200
@@ -211,6 +211,7 @@ enum
 	NET_SCTP=17,
 	NET_LLC=18,
 	NET_NETFILTER=19,
+	NET_NFS=20,
 };
 
 /* /proc/sys/kernel/random */
@@ -683,6 +684,11 @@ enum {
 	NET_DECNET_DEBUG_LEVEL = 255
 };
 
+/* /proc/sys/net/nfs/ */
+enum {
+	NET_NFS_NOAC_TIMEOUT	= 1
+};
+
 /* /proc/sys/net/decnet/conf/<dev> */
 enum {
 	NET_DECNET_CONF_LOOPBACK = -2,