text: /*
   *  linux/fs/nfs/inode.c
   *
   *  Copyright (C) 1992  Rick Sladkey
   *
   *  nfs inode and superblock handling functions
   *
   *  Modularised by Alan Cox <Alan.Cox@linux.org>, while hacking some
   *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
   *
   *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
   *  J.S.Peatfield@damtp.cam.ac.uk
   *
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  
  #include <linux/time.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/string.h>
  #include <linux/stat.h>
  #include <linux/errno.h>
  #include <linux/unistd.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/stats.h>
  #include <linux/sunrpc/metrics.h>
  #include <linux/nfs_fs.h>
  #include <linux/nfs_mount.h>
  #include <linux/nfs4_mount.h>
  #include <linux/lockd/bind.h>
  #include <linux/smp_lock.h>
  #include <linux/seq_file.h>
  #include <linux/mount.h>
  #include <linux/nfs_idmap.h>
  #include <linux/vfs.h>
  #include <linux/inet.h>
  #include <linux/nfs_xdr.h>
  
  #include <asm/system.h>
  #include <asm/uaccess.h>
  
  #include "nfs4_fs.h"
  #include "callback.h"
  #include "delegation.h"
  #include "iostat.h"
  #include "internal.h"
  
  #define NFSDBG_FACILITY		NFSDBG_VFS
  #define NFS_PARANOIA 1
  
  static void nfs_invalidate_inode(struct inode *);
  static int nfs_update_inode(struct inode *, struct nfs_fattr *);
  
  static void nfs_zap_acl_cache(struct inode *);
  
  static struct kmem_cache * nfs_inode_cachep;
  
  static inline unsigned long
  nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
  {
  	return nfs_fileid_to_ino_t(fattr->fileid);
  }
  
  int nfs_write_inode(struct inode *inode, int sync)
  {
  	int ret;
  
  	if (sync) {
  		ret = filemap_fdatawait(inode->i_mapping);
  		if (ret == 0)
  			ret = nfs_commit_inode(inode, FLUSH_SYNC);
  	} else
  		ret = nfs_commit_inode(inode, 0);
  	if (ret >= 0)
  		return 0;
  	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
  	return ret;
  }
  
  void nfs_clear_inode(struct inode *inode)
  {
  	/*
  	 * The following should never happen...
  	 */
  	BUG_ON(nfs_have_writebacks(inode));
  	BUG_ON(!list_empty(&NFS_I(inode)->open_files));
  	BUG_ON(atomic_read(&NFS_I(inode)->data_updates) != 0);
  	nfs_zap_acl_cache(inode);
  	nfs_access_zap_cache(inode);
  }
  
  /**
   * nfs_sync_mapping - helper to flush all mmapped dirty data to disk
   */
  int nfs_sync_mapping(struct address_space *mapping)
  {
  	int ret;
  
  	if (mapping->nrpages == 0)
  		return 0;
  	unmap_mapping_range(mapping, 0, 0, 0);
  	ret = filemap_write_and_wait(mapping);
  	if (ret != 0)
  		goto out;
  	ret = nfs_wb_all(mapping->host);
  out:
  	return ret;
  }
  
  /*
   * Invalidate the local caches
   */
  static void nfs_zap_caches_locked(struct inode *inode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	int mode = inode->i_mode;
  
  	nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);
  
  	NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
  	NFS_ATTRTIMEO_UPDATE(inode) = jiffies;
  
  	memset(NFS_COOKIEVERF(inode), 0, sizeof(NFS_COOKIEVERF(inode)));
  	if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL|NFS_INO_REVAL_PAGECACHE;
  	else
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL|NFS_INO_REVAL_PAGECACHE;
  }
  
  void nfs_zap_caches(struct inode *inode)
  {
  	spin_lock(&inode->i_lock);
  	nfs_zap_caches_locked(inode);
  	spin_unlock(&inode->i_lock);
  }
  
  void nfs_zap_mapping(struct inode *inode, struct address_space *mapping)
  {
  	if (mapping->nrpages != 0) {
  		spin_lock(&inode->i_lock);
  		NFS_I(inode)->cache_validity |= NFS_INO_INVALID_DATA;
  		spin_unlock(&inode->i_lock);
  	}
  }
  
  static void nfs_zap_acl_cache(struct inode *inode)
  {
  	void (*clear_acl_cache)(struct inode *);
  
  	clear_acl_cache = NFS_PROTO(inode)->clear_acl_cache;
  	if (clear_acl_cache != NULL)
  		clear_acl_cache(inode);
  	spin_lock(&inode->i_lock);
  	NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_ACL;
  	spin_unlock(&inode->i_lock);
  }
  
  /*
   * Invalidate, but do not unhash, the inode.
   * NB: must be called with inode->i_lock held!
   */
  static void nfs_invalidate_inode(struct inode *inode)
  {
  	set_bit(NFS_INO_STALE, &NFS_FLAGS(inode));
  	nfs_zap_caches_locked(inode);
  }
  
  struct nfs_find_desc {
  	struct nfs_fh		*fh;
  	struct nfs_fattr	*fattr;
  };
  
  /*
   * In NFSv3 we can have 64bit inode numbers. In order to support
   * this, and re-exported directories (also seen in NFSv2)
   * we are forced to allow 2 different inodes to have the same
   * i_ino.
   */
  static int
  nfs_find_actor(struct inode *inode, void *opaque)
  {
  	struct nfs_find_desc	*desc = (struct nfs_find_desc *)opaque;
  	struct nfs_fh		*fh = desc->fh;
  	struct nfs_fattr	*fattr = desc->fattr;
  
  	if (NFS_FILEID(inode) != fattr->fileid)
  		return 0;
  	if (nfs_compare_fh(NFS_FH(inode), fh))
  		return 0;
  	if (is_bad_inode(inode) || NFS_STALE(inode))
  		return 0;
  	return 1;
  }
  
  static int
  nfs_init_locked(struct inode *inode, void *opaque)
  {
  	struct nfs_find_desc	*desc = (struct nfs_find_desc *)opaque;
  	struct nfs_fattr	*fattr = desc->fattr;
  
  	NFS_FILEID(inode) = fattr->fileid;
  	nfs_copy_fh(NFS_FH(inode), desc->fh);
  	return 0;
  }
  
  /* Don't use READDIRPLUS on directories that we believe are too large */
  #define NFS_LIMIT_READDIRPLUS (8*PAGE_SIZE)
  
  /*
   * This is our front-end to iget that looks up inodes by file handle
   * instead of inode number.
   */
  struct inode *
  nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
  {
  	struct nfs_find_desc desc = {
  		.fh	= fh,
  		.fattr	= fattr
  	};
  	struct inode *inode = ERR_PTR(-ENOENT);
  	unsigned long hash;
  
  	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
  		goto out_no_inode;
  
  	if (!fattr->nlink) {
  		printk("NFS: Buggy server - nlink == 0!\n");
  		goto out_no_inode;
  	}
  
  	hash = nfs_fattr_to_ino_t(fattr);
  
  	inode = iget5_locked(sb, hash, nfs_find_actor, nfs_init_locked, &desc);
  	if (inode == NULL) {
  		inode = ERR_PTR(-ENOMEM);
  		goto out_no_inode;
  	}
  
  	if (inode->i_state & I_NEW) {
  		struct nfs_inode *nfsi = NFS_I(inode);
  		unsigned long now = jiffies;
  
  		/* We set i_ino for the few things that still rely on it,
  		 * such as stat(2) */
  		inode->i_ino = hash;
  
  		/* We can't support update_atime(), since the server will reset it */
  		inode->i_flags |= S_NOATIME|S_NOCMTIME;
  		inode->i_mode = fattr->mode;
  		/* Why so? Because we want revalidate for devices/FIFOs, and
  		 * that's precisely what we have in nfs_file_inode_operations.
  		 */
  		inode->i_op = NFS_SB(sb)->nfs_client->rpc_ops->file_inode_ops;
  		if (S_ISREG(inode->i_mode)) {
  			inode->i_fop = &nfs_file_operations;
  			inode->i_data.a_ops = &nfs_file_aops;
  			inode->i_data.backing_dev_info = &NFS_SB(sb)->backing_dev_info;
  		} else if (S_ISDIR(inode->i_mode)) {
  			inode->i_op = NFS_SB(sb)->nfs_client->rpc_ops->dir_inode_ops;
  			inode->i_fop = &nfs_dir_operations;
  			if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS)
  			    && fattr->size <= NFS_LIMIT_READDIRPLUS)
  				set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_FLAGS(inode));
  			/* Deal with crossing mountpoints */
  			if (!nfs_fsid_equal(&NFS_SB(sb)->fsid, &fattr->fsid)) {
  				if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
  					inode->i_op = &nfs_referral_inode_operations;
  				else
  					inode->i_op = &nfs_mountpoint_inode_operations;
  				inode->i_fop = NULL;
  			}
  		} else if (S_ISLNK(inode->i_mode))
  			inode->i_op = &nfs_symlink_inode_operations;
  		else
  			init_special_inode(inode, inode->i_mode, fattr->rdev);
  
  		nfsi->read_cache_jiffies = fattr->time_start;
  		nfsi->last_updated = now;
  		nfsi->cache_change_attribute = now;
  		inode->i_atime = fattr->atime;
  		inode->i_mtime = fattr->mtime;
  		inode->i_ctime = fattr->ctime;
  		if (fattr->valid & NFS_ATTR_FATTR_V4)
  			nfsi->change_attr = fattr->change_attr;
  		inode->i_size = nfs_size_to_loff_t(fattr->size);
  		inode->i_nlink = fattr->nlink;
  		inode->i_uid = fattr->uid;
  		inode->i_gid = fattr->gid;
  		if (fattr->valid & (NFS_ATTR_FATTR_V3 | NFS_ATTR_FATTR_V4)) {
  			/*
  			 * report the blocks in 512byte units
  			 */
  			inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
  		} else {
  			inode->i_blocks = fattr->du.nfs2.blocks;
  		}
  		nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
  		nfsi->attrtimeo_timestamp = now;
  		memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
  		nfsi->access_cache = RB_ROOT;
  
  		unlock_new_inode(inode);
  	} else
  		nfs_refresh_inode(inode, fattr);
  	dprintk("NFS: nfs_fhget(%s/%Ld ct=%d)\n",
  		inode->i_sb->s_id,
  		(long long)NFS_FILEID(inode),
  		atomic_read(&inode->i_count));
  
  out:
  	return inode;
  
  out_no_inode:
  	dprintk("nfs_fhget: iget failed with error %ld\n", PTR_ERR(inode));
  	goto out;
  }
  
  #define NFS_VALID_ATTRS (ATTR_MODE|ATTR_UID|ATTR_GID|ATTR_SIZE|ATTR_ATIME|ATTR_ATIME_SET|ATTR_MTIME|ATTR_MTIME_SET)
  
  int
  nfs_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	struct inode *inode = dentry->d_inode;
  	struct nfs_fattr fattr;
  	int error;
  
  	nfs_inc_stats(inode, NFSIOS_VFSSETATTR);
  
  	if (attr->ia_valid & ATTR_SIZE) {
  		if (!S_ISREG(inode->i_mode) || attr->ia_size == i_size_read(inode))
  			attr->ia_valid &= ~ATTR_SIZE;
  	}
  
  	/* Optimization: if the end result is no change, don't RPC */
  	attr->ia_valid &= NFS_VALID_ATTRS;
  	if (attr->ia_valid == 0)
  		return 0;
  
  	lock_kernel();
  	nfs_begin_data_update(inode);
  	/* Write all dirty data */
  	if (S_ISREG(inode->i_mode)) {
  		filemap_write_and_wait(inode->i_mapping);
  		nfs_wb_all(inode);
  	}
  	/*
  	 * Return any delegations if we're going to change ACLs
  	 */
  	if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0)
  		nfs_inode_return_delegation(inode);
  	error = NFS_PROTO(inode)->setattr(dentry, &fattr, attr);
  	if (error == 0)
  		nfs_refresh_inode(inode, &fattr);
  	nfs_end_data_update(inode);
  	unlock_kernel();
  	return error;
  }
  
  /**
   * nfs_setattr_update_inode - Update inode metadata after a setattr call.
   * @inode: pointer to struct inode
   * @attr: pointer to struct iattr
   *
   * Note: we do this in the *proc.c in order to ensure that
   *       it works for things like exclusive creates too.
   */
  void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr)
  {
  	if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0) {
  		if ((attr->ia_valid & ATTR_MODE) != 0) {
  			int mode = attr->ia_mode & S_IALLUGO;
  			mode |= inode->i_mode & ~S_IALLUGO;
  			inode->i_mode = mode;
  		}
  		if ((attr->ia_valid & ATTR_UID) != 0)
  			inode->i_uid = attr->ia_uid;
  		if ((attr->ia_valid & ATTR_GID) != 0)
  			inode->i_gid = attr->ia_gid;
  		spin_lock(&inode->i_lock);
  		NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  		spin_unlock(&inode->i_lock);
  	}
  	if ((attr->ia_valid & ATTR_SIZE) != 0) {
  		nfs_inc_stats(inode, NFSIOS_SETATTRTRUNC);
  		inode->i_size = attr->ia_size;
  		vmtruncate(inode, attr->ia_size);
  	}
  }
  
  static int nfs_wait_schedule(void *word)
  {
  	if (signal_pending(current))
  		return -ERESTARTSYS;
  	schedule();
  	return 0;
  }
  
  /*
   * Wait for the inode to get unlocked.
   */
  static int nfs_wait_on_inode(struct inode *inode)
  {
  	struct rpc_clnt	*clnt = NFS_CLIENT(inode);
  	struct nfs_inode *nfsi = NFS_I(inode);
  	sigset_t oldmask;
  	int error;
  
  	rpc_clnt_sigmask(clnt, &oldmask);
  	error = wait_on_bit_lock(&nfsi->flags, NFS_INO_REVALIDATING,
  					nfs_wait_schedule, TASK_INTERRUPTIBLE);
  	rpc_clnt_sigunmask(clnt, &oldmask);
  
  	return error;
  }
  
  static void nfs_wake_up_inode(struct inode *inode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	clear_bit(NFS_INO_REVALIDATING, &nfsi->flags);
  	smp_mb__after_clear_bit();
  	wake_up_bit(&nfsi->flags, NFS_INO_REVALIDATING);
  }
  
  int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  {
  	struct inode *inode = dentry->d_inode;
  	int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
  	int err;
  
  	/* Flush out writes to the server in order to update c/mtime */
  	if (S_ISREG(inode->i_mode))
  		nfs_sync_mapping_range(inode->i_mapping, 0, 0, FLUSH_NOCOMMIT);
  
  	/*
  	 * We may force a getattr if the user cares about atime.
  	 *
  	 * Note that we only have to check the vfsmount flags here:
  	 *  - NFS always sets S_NOATIME by so checking it would give a
  	 *    bogus result
  	 *  - NFS never sets MS_NOATIME or MS_NODIRATIME so there is
  	 *    no point in checking those.
  	 */
   	if ((mnt->mnt_flags & MNT_NOATIME) ||
   	    ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
  		need_atime = 0;
  
  	if (need_atime)
  		err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
  	else
  		err = nfs_revalidate_inode(NFS_SERVER(inode), inode);
  	if (!err)
  		generic_fillattr(inode, stat);
  	return err;
  }
  
  static struct nfs_open_context *alloc_nfs_open_context(struct vfsmount *mnt, struct dentry *dentry, struct rpc_cred *cred)
  {
  	struct nfs_open_context *ctx;
  
  	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
  	if (ctx != NULL) {
  		atomic_set(&ctx->count, 1);
  		ctx->dentry = dget(dentry);
  		ctx->vfsmnt = mntget(mnt);
  		ctx->cred = get_rpccred(cred);
  		ctx->state = NULL;
  		ctx->lockowner = current->files;
  		ctx->error = 0;
  		ctx->dir_cookie = 0;
  	}
  	return ctx;
  }
  
  struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)
  {
  	if (ctx != NULL)
  		atomic_inc(&ctx->count);
  	return ctx;
  }
  
  void put_nfs_open_context(struct nfs_open_context *ctx)
  {
  	if (atomic_dec_and_test(&ctx->count)) {
  		if (!list_empty(&ctx->list)) {
  			struct inode *inode = ctx->dentry->d_inode;
  			spin_lock(&inode->i_lock);
  			list_del(&ctx->list);
  			spin_unlock(&inode->i_lock);
  		}
  		if (ctx->state != NULL)
  			nfs4_close_state(ctx->state, ctx->mode);
  		if (ctx->cred != NULL)
  			put_rpccred(ctx->cred);
  		dput(ctx->dentry);
  		mntput(ctx->vfsmnt);
  		kfree(ctx);
  	}
  }
  
  /*
   * Ensure that mmap has a recent RPC credential for use when writing out
   * shared pages
   */
  static void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx)
  {
  	struct inode *inode = filp->f_path.dentry->d_inode;
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	filp->private_data = get_nfs_open_context(ctx);
  	spin_lock(&inode->i_lock);
  	list_add(&ctx->list, &nfsi->open_files);
  	spin_unlock(&inode->i_lock);
  }
  
  /*
   * Given an inode, search for an open context with the desired characteristics
   */
  struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, int mode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	struct nfs_open_context *pos, *ctx = NULL;
  
  	spin_lock(&inode->i_lock);
  	list_for_each_entry(pos, &nfsi->open_files, list) {
  		if (cred != NULL && pos->cred != cred)
  			continue;
  		if ((pos->mode & mode) == mode) {
  			ctx = get_nfs_open_context(pos);
  			break;
  		}
  	}
  	spin_unlock(&inode->i_lock);
  	return ctx;
  }
  
  static void nfs_file_clear_open_context(struct file *filp)
  {
  	struct inode *inode = filp->f_path.dentry->d_inode;
  	struct nfs_open_context *ctx = (struct nfs_open_context *)filp->private_data;
  
  	if (ctx) {
  		filp->private_data = NULL;
  		spin_lock(&inode->i_lock);
  		list_move_tail(&ctx->list, &NFS_I(inode)->open_files);
  		spin_unlock(&inode->i_lock);
  		put_nfs_open_context(ctx);
  	}
  }
  
  /*
   * These allocate and release file read/write context information.
   */
  int nfs_open(struct inode *inode, struct file *filp)
  {
  	struct nfs_open_context *ctx;
  	struct rpc_cred *cred;
  
  	cred = rpcauth_lookupcred(NFS_CLIENT(inode)->cl_auth, 0);
  	if (IS_ERR(cred))
  		return PTR_ERR(cred);
  	ctx = alloc_nfs_open_context(filp->f_path.mnt, filp->f_path.dentry, cred);
  	put_rpccred(cred);
  	if (ctx == NULL)
  		return -ENOMEM;
  	ctx->mode = filp->f_mode;
  	nfs_file_set_open_context(filp, ctx);
  	put_nfs_open_context(ctx);
  	return 0;
  }
  
  int nfs_release(struct inode *inode, struct file *filp)
  {
  	nfs_file_clear_open_context(filp);
  	return 0;
  }
  
  /*
   * This function is called whenever some part of NFS notices that
   * the cached attributes have to be refreshed.
   */
  int
  __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
  {
  	int		 status = -ESTALE;
  	struct nfs_fattr fattr;
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	dfprintk(PAGECACHE, "NFS: revalidating (%s/%Ld)\n",
  		inode->i_sb->s_id, (long long)NFS_FILEID(inode));
  
  	nfs_inc_stats(inode, NFSIOS_INODEREVALIDATE);
  	lock_kernel();
  	if (is_bad_inode(inode))
   		goto out_nowait;
  	if (NFS_STALE(inode))
   		goto out_nowait;
  
  	status = nfs_wait_on_inode(inode);
  	if (status < 0)
  		goto out;
  	if (NFS_STALE(inode)) {
  		status = -ESTALE;
  		/* Do we trust the cached ESTALE? */
  		if (NFS_ATTRTIMEO(inode) != 0) {
  			if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME)) {
  				/* no */
  			} else
  				goto out;
  		}
  	}
  
  	status = NFS_PROTO(inode)->getattr(server, NFS_FH(inode), &fattr);
  	if (status != 0) {
  		dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) getattr failed, error=%d\n",
  			 inode->i_sb->s_id,
  			 (long long)NFS_FILEID(inode), status);
  		if (status == -ESTALE) {
  			nfs_zap_caches(inode);
  			if (!S_ISDIR(inode->i_mode))
  				set_bit(NFS_INO_STALE, &NFS_FLAGS(inode));
  		}
  		goto out;
  	}
  
  	spin_lock(&inode->i_lock);
  	status = nfs_update_inode(inode, &fattr);
  	if (status) {
  		spin_unlock(&inode->i_lock);
  		dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) refresh failed, error=%d\n",
  			 inode->i_sb->s_id,
  			 (long long)NFS_FILEID(inode), status);
  		goto out;
  	}
  	spin_unlock(&inode->i_lock);
  
  	if (nfsi->cache_validity & NFS_INO_INVALID_ACL)
  		nfs_zap_acl_cache(inode);
  
  	dfprintk(PAGECACHE, "NFS: (%s/%Ld) revalidation complete\n",
  		inode->i_sb->s_id,
  		(long long)NFS_FILEID(inode));
  
   out:
  	nfs_wake_up_inode(inode);
  
   out_nowait:
  	unlock_kernel();
  	return status;
  }
  
  int nfs_attribute_timeout(struct inode *inode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	if (nfs_have_delegation(inode, FMODE_READ))
  		return 0;
  	return time_after(jiffies, nfsi->read_cache_jiffies+nfsi->attrtimeo);
  }
  
  /**
   * nfs_revalidate_inode - Revalidate the inode attributes
   * @server - pointer to nfs_server struct
   * @inode - pointer to inode struct
   *
   * Updates inode attribute information by retrieving the data from the server.
   */
  int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
  {
  	if (!(NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATTR)
  			&& !nfs_attribute_timeout(inode))
  		return NFS_STALE(inode) ? -ESTALE : 0;
  	return __nfs_revalidate_inode(server, inode);
  }
  
  static int nfs_invalidate_mapping_nolock(struct inode *inode, struct address_space *mapping)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	
  	if (mapping->nrpages != 0) {
  		int ret = invalidate_inode_pages2(mapping);
  		if (ret < 0)
  			return ret;
  	}
  	spin_lock(&inode->i_lock);
  	nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
  	if (S_ISDIR(inode->i_mode)) {
  		memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
  		/* This ensures we revalidate child dentries */
  		nfsi->cache_change_attribute = jiffies;
  	}
  	spin_unlock(&inode->i_lock);
  	nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
  	dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated\n",
  			inode->i_sb->s_id, (long long)NFS_FILEID(inode));
  	return 0;
  }
  
  static int nfs_invalidate_mapping(struct inode *inode, struct address_space *mapping)
  {
  	int ret = 0;
  
  	mutex_lock(&inode->i_mutex);
  	if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_DATA) {
  		ret = nfs_sync_mapping(mapping);
  		if (ret == 0)
  			ret = nfs_invalidate_mapping_nolock(inode, mapping);
  	}
  	mutex_unlock(&inode->i_mutex);
  	return ret;
  }
  
  /**
   * nfs_revalidate_mapping_nolock - Revalidate the pagecache
   * @inode - pointer to host inode
   * @mapping - pointer to mapping
   */
  int nfs_revalidate_mapping_nolock(struct inode *inode, struct address_space *mapping)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	int ret = 0;
  
  	if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
  			|| nfs_attribute_timeout(inode) || NFS_STALE(inode)) {
  		ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
  		if (ret < 0)
  			goto out;
  	}
  	if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
  		ret = nfs_invalidate_mapping_nolock(inode, mapping);
  out:
  	return ret;
  }
  
  /**
   * nfs_revalidate_mapping - Revalidate the pagecache
   * @inode - pointer to host inode
   * @mapping - pointer to mapping
   *
   * This version of the function will take the inode->i_mutex and attempt to
   * flush out all dirty data if it needs to invalidate the page cache.
   */
  int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	int ret = 0;
  
  	if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
  			|| nfs_attribute_timeout(inode) || NFS_STALE(inode)) {
  		ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
  		if (ret < 0)
  			goto out;
  	}
  	if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
  		ret = nfs_invalidate_mapping(inode, mapping);
  out:
  	return ret;
  }
  
  /**
   * nfs_begin_data_update
   * @inode - pointer to inode
   * Declare that a set of operations will update file data on the server
   */
  void nfs_begin_data_update(struct inode *inode)
  {
  	atomic_inc(&NFS_I(inode)->data_updates);
  }
  
  /**
   * nfs_end_data_update
   * @inode - pointer to inode
   * Declare end of the operations that will update file data
   * This will mark the inode as immediately needing revalidation
   * of its attribute cache.
   */
  void nfs_end_data_update(struct inode *inode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	/* Directories: invalidate page cache */
  	if (S_ISDIR(inode->i_mode)) {
  		spin_lock(&inode->i_lock);
  		nfsi->cache_validity |= NFS_INO_INVALID_DATA;
  		spin_unlock(&inode->i_lock);
  	}
  	nfsi->cache_change_attribute = jiffies;
  	atomic_dec(&nfsi->data_updates);
  }
  
  static void nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	unsigned long now = jiffies;
  
  	/* If we have atomic WCC data, we may update some attributes */
  	if ((fattr->valid & NFS_ATTR_WCC) != 0) {
  		if (timespec_equal(&inode->i_ctime, &fattr->pre_ctime)) {
  			memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
  			nfsi->cache_change_attribute = now;
  		}
  		if (timespec_equal(&inode->i_mtime, &fattr->pre_mtime)) {
  			memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
  			nfsi->cache_change_attribute = now;
  		}
  		if (inode->i_size == fattr->pre_size && nfsi->npages == 0) {
  			inode->i_size = fattr->size;
  			nfsi->cache_change_attribute = now;
  		}
  	}
  }
  
  /**
   * nfs_check_inode_attributes - verify consistency of the inode attribute cache
   * @inode - pointer to inode
   * @fattr - updated attributes
   *
   * Verifies the attribute cache. If we have just changed the attributes,
   * so that fattr carries weak cache consistency data, then it may
   * also update the ctime/mtime/change_attribute.
   */
  static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fattr)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	loff_t cur_size, new_isize;
  	int data_unstable;
  
  
  	/* Has the inode gone and changed behind our back? */
  	if (nfsi->fileid != fattr->fileid
  			|| (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) {
  		return -EIO;
  	}
  
  	/* Are we in the process of updating data on the server? */
  	data_unstable = nfs_caches_unstable(inode);
  
  	/* Do atomic weak cache consistency updates */
  	nfs_wcc_update_inode(inode, fattr);
  
  	if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0 &&
  			nfsi->change_attr != fattr->change_attr)
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
  
  	/* Verify a few of the more important attributes */
  	if (!timespec_equal(&inode->i_mtime, &fattr->mtime))
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
  
  	cur_size = i_size_read(inode);
   	new_isize = nfs_size_to_loff_t(fattr->size);
  	if (cur_size != new_isize && nfsi->npages == 0)
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
  
  	/* Have any file permissions changed? */
  	if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO)
  			|| inode->i_uid != fattr->uid
  			|| inode->i_gid != fattr->gid)
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
  
  	/* Has the link count changed? */
  	if (inode->i_nlink != fattr->nlink)
  		nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
  
  	if (!timespec_equal(&inode->i_atime, &fattr->atime))
  		nfsi->cache_validity |= NFS_INO_INVALID_ATIME;
  
  	nfsi->read_cache_jiffies = fattr->time_start;
  	return 0;
  }
  
  /**
   * nfs_refresh_inode - try to update the inode attribute cache
   * @inode - pointer to inode
   * @fattr - updated attributes
   *
   * Check that an RPC call that returned attributes has not overlapped with
   * other recent updates of the inode metadata, then decide whether it is
   * safe to do a full update of the inode attributes, or whether just to
   * call nfs_check_inode_attributes.
   */
  int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	int status;
  
  	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
  		return 0;
  	spin_lock(&inode->i_lock);
  	if (time_after(fattr->time_start, nfsi->last_updated))
  		status = nfs_update_inode(inode, fattr);
  	else
  		status = nfs_check_inode_attributes(inode, fattr);
  
  	spin_unlock(&inode->i_lock);
  	return status;
  }
  
  /**
   * nfs_post_op_update_inode - try to update the inode attribute cache
   * @inode - pointer to inode
   * @fattr - updated attributes
   *
   * After an operation that has changed the inode metadata, mark the
   * attribute cache as being invalid, then try to update it.
   *
   * NB: if the server didn't return any post op attributes, this
   * function will force the retrieval of attributes before the next
   * NFS request.  Thus it should be used only for operations that
   * are expected to change one or more attributes, to avoid
   * unnecessary NFS requests and trips through nfs_update_inode().
   */
  int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	int status = 0;
  
  	spin_lock(&inode->i_lock);
  	if (unlikely((fattr->valid & NFS_ATTR_FATTR) == 0)) {
  		nfsi->cache_validity |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
  		goto out;
  	}
  	status = nfs_update_inode(inode, fattr);
  out:
  	spin_unlock(&inode->i_lock);
  	return status;
  }
  
  /*
   * Many nfs protocol calls return the new file attributes after
   * an operation.  Here we update the inode to reflect the state
   * of the server's inode.
   *
   * This is a bit tricky because we have to make sure all dirty pages
   * have been sent off to the server before calling invalidate_inode_pages.
   * To make sure no other process adds more write requests while we try
   * our best to flush them, we make them sleep during the attribute refresh.
   *
   * A very similar scenario holds for the dir cache.
   */
  static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
  {
  	struct nfs_server *server;
  	struct nfs_inode *nfsi = NFS_I(inode);
  	loff_t cur_isize, new_isize;
  	unsigned int	invalid = 0;
  	unsigned long now = jiffies;
  	int data_stable;
  
  	dfprintk(VFS, "NFS: %s(%s/%ld ct=%d info=0x%x)\n",
  			__FUNCTION__, inode->i_sb->s_id, inode->i_ino,
  			atomic_read(&inode->i_count), fattr->valid);
  
  	if (nfsi->fileid != fattr->fileid)
  		goto out_fileid;
  
  	/*
  	 * Make sure the inode's type hasn't changed.
  	 */
  	if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
  		goto out_changed;
  
  	server = NFS_SERVER(inode);
  	/* Update the fsid if and only if this is the root directory */
  	if (inode == inode->i_sb->s_root->d_inode
  			&& !nfs_fsid_equal(&server->fsid, &fattr->fsid))
  		server->fsid = fattr->fsid;
  
  	/*
  	 * Update the read time so we don't revalidate too often.
  	 */
  	nfsi->read_cache_jiffies = fattr->time_start;
  	nfsi->last_updated = now;
  
  	/* Fix a wraparound issue with nfsi->cache_change_attribute */
  	if (time_before(now, nfsi->cache_change_attribute))
  		nfsi->cache_change_attribute = now - 600*HZ;
  
  	/* Are we racing with known updates of the metadata on the server? */
  	data_stable = nfs_verify_change_attribute(inode, fattr->time_start);
  	if (data_stable)
  		nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_ATIME);
  
  	/* Do atomic weak cache consistency updates */
  	nfs_wcc_update_inode(inode, fattr);
  
  	/* Check if our cached file size is stale */
   	new_isize = nfs_size_to_loff_t(fattr->size);
  	cur_isize = i_size_read(inode);
  	if (new_isize != cur_isize) {
  		/* Do we perhaps have any outstanding writes? */
  		if (nfsi->npages == 0) {
  			/* No, but did we race with nfs_end_data_update()? */
  			if (data_stable) {
  				inode->i_size = new_isize;
  				invalid |= NFS_INO_INVALID_DATA;
  			}
  			invalid |= NFS_INO_INVALID_ATTR;
  		} else if (new_isize > cur_isize) {
  			inode->i_size = new_isize;
  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
  		}
  		nfsi->cache_change_attribute = now;
  		dprintk("NFS: isize change on server for file %s/%ld\n",
  				inode->i_sb->s_id, inode->i_ino);
  	}
  
  	/* Check if the mtime agrees */
  	if (!timespec_equal(&inode->i_mtime, &fattr->mtime)) {
  		memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
  		dprintk("NFS: mtime change on server for file %s/%ld\n",
  				inode->i_sb->s_id, inode->i_ino);
  		invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
  		nfsi->cache_change_attribute = now;
  	}
  
  	/* If ctime has changed we should definitely clear access+acl caches */
  	if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) {
  		invalid |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  		memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
  		nfsi->cache_change_attribute = now;
  	}
  	memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));
  
  	if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO) ||
  	    inode->i_uid != fattr->uid ||
  	    inode->i_gid != fattr->gid)
  		invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  
  	inode->i_mode = fattr->mode;
  	inode->i_nlink = fattr->nlink;
  	inode->i_uid = fattr->uid;
  	inode->i_gid = fattr->gid;
  
  	if (fattr->valid & (NFS_ATTR_FATTR_V3 | NFS_ATTR_FATTR_V4)) {
  		/*
  		 * report the blocks in 512byte units
  		 */
  		inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
   	} else {
   		inode->i_blocks = fattr->du.nfs2.blocks;
   	}
  
  	if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0 &&
  			nfsi->change_attr != fattr->change_attr) {
  		dprintk("NFS: change_attr change on server for file %s/%ld\n",
  				inode->i_sb->s_id, inode->i_ino);
  		nfsi->change_attr = fattr->change_attr;
  		invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  		nfsi->cache_change_attribute = now;
  	}
  
  	/* Update attrtimeo value if we're out of the unstable period */
  	if (invalid & NFS_INO_INVALID_ATTR) {
  		nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);
  		nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
  		nfsi->attrtimeo_timestamp = now;
  	} else if (time_after(now, nfsi->attrtimeo_timestamp+nfsi->attrtimeo)) {
  		if ((nfsi->attrtimeo <<= 1) > NFS_MAXATTRTIMEO(inode))
  			nfsi->attrtimeo = NFS_MAXATTRTIMEO(inode);
  		nfsi->attrtimeo_timestamp = now;
  	}
  	/* Don't invalidate the data if we were to blame */
  	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
  				|| S_ISLNK(inode->i_mode)))
  		invalid &= ~NFS_INO_INVALID_DATA;
  	if (data_stable)
  		invalid &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME|NFS_INO_REVAL_PAGECACHE);
  	if (!nfs_have_delegation(inode, FMODE_READ))
  		nfsi->cache_validity |= invalid;
  
  	return 0;
   out_changed:
  	/*
  	 * Big trouble! The inode has become a different object.
  	 */
  #ifdef NFS_PARANOIA
  	printk(KERN_DEBUG "%s: inode %ld mode changed, %07o to %07o\n",
  			__FUNCTION__, inode->i_ino, inode->i_mode, fattr->mode);
  #endif
   out_err:
  	/*
  	 * No need to worry about unhashing the dentry, as the
  	 * lookup validation will know that the inode is bad.
  	 * (But we fall through to invalidate the caches.)
  	 */
  	nfs_invalidate_inode(inode);
  	return -ESTALE;
  
   out_fileid:
  	printk(KERN_ERR "NFS: server %s error: fileid changed\n"
  		"fsid %s: expected fileid 0x%Lx, got 0x%Lx\n",
  		NFS_SERVER(inode)->nfs_client->cl_hostname, inode->i_sb->s_id,
  		(long long)nfsi->fileid, (long long)fattr->fileid);
  	goto out_err;
  }
  
  
  #ifdef CONFIG_NFS_V4
  
  /*
   * Clean out any remaining NFSv4 state that might be left over due
   * to open() calls that passed nfs_atomic_lookup, but failed to call
   * nfs_open().
   */
  void nfs4_clear_inode(struct inode *inode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	/* If we are holding a delegation, return it! */
  	nfs_inode_return_delegation(inode);
  	/* First call standard NFS clear_inode() code */
  	nfs_clear_inode(inode);
  	/* Now clear out any remaining state */
  	while (!list_empty(&nfsi->open_states)) {
  		struct nfs4_state *state;
  		
  		state = list_entry(nfsi->open_states.next,
  				struct nfs4_state,
  				inode_states);
  		dprintk("%s(%s/%Ld): found unclaimed NFSv4 state %p\n",
  				__FUNCTION__,
  				inode->i_sb->s_id,
  				(long long)NFS_FILEID(inode),
  				state);
  		BUG_ON(atomic_read(&state->count) != 1);
  		nfs4_close_state(state, state->state);
  	}
  }
  #endif
  
  struct inode *nfs_alloc_inode(struct super_block *sb)
  {
  	struct nfs_inode *nfsi;
  	nfsi = (struct nfs_inode *)kmem_cache_alloc(nfs_inode_cachep, GFP_KERNEL);
  	if (!nfsi)
  		return NULL;
  	nfsi->flags = 0UL;
  	nfsi->cache_validity = 0UL;
  #ifdef CONFIG_NFS_V3_ACL
  	nfsi->acl_access = ERR_PTR(-EAGAIN);
  	nfsi->acl_default = ERR_PTR(-EAGAIN);
  #endif
  #ifdef CONFIG_NFS_V4
  	nfsi->nfs4_acl = NULL;
  #endif /* CONFIG_NFS_V4 */
  	return &nfsi->vfs_inode;
  }
  
  void nfs_destroy_inode(struct inode *inode)
  {
  	kmem_cache_free(nfs_inode_cachep, NFS_I(inode));
  }
  
  static inline void nfs4_init_once(struct nfs_inode *nfsi)
  {
  #ifdef CONFIG_NFS_V4
  	INIT_LIST_HEAD(&nfsi->open_states);
  	nfsi->delegation = NULL;
  	nfsi->delegation_state = 0;
  	init_rwsem(&nfsi->rwsem);
  #endif
  }
  
  static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
  {
  	struct nfs_inode *nfsi = (struct nfs_inode *) foo;
  
  	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
  	    SLAB_CTOR_CONSTRUCTOR) {
  		inode_init_once(&nfsi->vfs_inode);
  		spin_lock_init(&nfsi->req_lock);
  		INIT_LIST_HEAD(&nfsi->dirty);
  		INIT_LIST_HEAD(&nfsi->commit);
  		INIT_LIST_HEAD(&nfsi->open_files);
  		INIT_LIST_HEAD(&nfsi->access_cache_entry_lru);
  		INIT_LIST_HEAD(&nfsi->access_cache_inode_lru);
  		INIT_RADIX_TREE(&nfsi->nfs_page_tree, GFP_ATOMIC);
  		atomic_set(&nfsi->data_updates, 0);
  		nfsi->ndirty = 0;
  		nfsi->ncommit = 0;
  		nfsi->npages = 0;
  		nfs4_init_once(nfsi);
  	}
  }
   
  static int __init nfs_init_inodecache(void)
  {
  	nfs_inode_cachep = kmem_cache_create("nfs_inode_cache",
  					     sizeof(struct nfs_inode),
  					     0, (SLAB_RECLAIM_ACCOUNT|
  						SLAB_MEM_SPREAD),
  					     init_once, NULL);
  	if (nfs_inode_cachep == NULL)
  		return -ENOMEM;
  
  	return 0;
  }
  
  static void nfs_destroy_inodecache(void)
  {
  	kmem_cache_destroy(nfs_inode_cachep);
  }
  
  /*
   * Initialize NFS
   */
  static int __init init_nfs_fs(void)
  {
  	int err;
  
  	err = nfs_fs_proc_init();
  	if (err)
  		goto out5;
  
  	err = nfs_init_nfspagecache();
  	if (err)
  		goto out4;
  
  	err = nfs_init_inodecache();
  	if (err)
  		goto out3;
  
  	err = nfs_init_readpagecache();
  	if (err)
  		goto out2;
  
  	err = nfs_init_writepagecache();
  	if (err)
  		goto out1;
  
  	err = nfs_init_directcache();
  	if (err)
  		goto out0;
  
  #ifdef CONFIG_PROC_FS
  	rpc_proc_register(&nfs_rpcstat);
  #endif
  	if ((err = register_nfs_fs()) != 0)
  		goto out;
  	return 0;
  out:
  #ifdef CONFIG_PROC_FS
  	rpc_proc_unregister("nfs");
  #endif
  	nfs_destroy_directcache();
  out0:
  	nfs_destroy_writepagecache();
  out1:
  	nfs_destroy_readpagecache();
  out2:
  	nfs_destroy_inodecache();
  out3:
  	nfs_destroy_nfspagecache();
  out4:
  	nfs_fs_proc_exit();
  out5:
  	return err;
  }
  
  static void __exit exit_nfs_fs(void)
  {
  	nfs_destroy_directcache();
  	nfs_destroy_writepagecache();
  	nfs_destroy_readpagecache();
  	nfs_destroy_inodecache();
  	nfs_destroy_nfspagecache();
  #ifdef CONFIG_PROC_FS
  	rpc_proc_unregister("nfs");
  #endif
  	unregister_nfs_fs();
  	nfs_fs_proc_exit();
  }
  
  /* Not quite true; I just maintain it */
  MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
  MODULE_LICENSE("GPL");
  
  module_init(init_nfs_fs)
  module_exit(exit_nfs_fs)
  