/*
   *  linux/fs/nfs/inode.c
   *
   *  Copyright (C) 1992  Rick Sladkey
   *
   *  nfs inode and superblock handling functions
   *

   *  Modularised by Alan Cox <alan@lxorguk.ukuu.org.uk>, 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/sched.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/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 <linux/slab.h>

  #include <linux/compat.h>

  #include <linux/freezer.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"

  #include "fscache.h"

  #include "dns_resolve.h"

  #include "pnfs.h"

  
  #define NFSDBG_FACILITY		NFSDBG_VFS

  #define NFS_64_BIT_INODE_NUMBERS_ENABLED	1
  
  /* Default is to see 64-bit inode numbers */

  static bool enable_ino64 = NFS_64_BIT_INODE_NUMBERS_ENABLED;

  static void nfs_invalidate_inode(struct inode *);

  static int nfs_update_inode(struct inode *, struct nfs_fattr *);

  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);
  }

  /**

   * nfs_wait_bit_killable - helper for functions that are sleeping on bit locks
   * @word: long word containing the bit lock
   */
  int nfs_wait_bit_killable(void *word)
  {
  	if (fatal_signal_pending(current))
  		return -ERESTARTSYS;

  	freezable_schedule();

  	return 0;
  }
  
  /**

   * nfs_compat_user_ino64 - returns the user-visible inode number
   * @fileid: 64-bit fileid
   *
   * This function returns a 32-bit inode number if the boot parameter
   * nfs.enable_ino64 is zero.
   */
  u64 nfs_compat_user_ino64(u64 fileid)
  {

  #ifdef CONFIG_COMPAT
  	compat_ulong_t ino;
  #else	
  	unsigned long ino;
  #endif

  
  	if (enable_ino64)
  		return fileid;
  	ino = fileid;
  	if (sizeof(ino) < sizeof(fileid))
  		ino ^= fileid >> (sizeof(fileid)-sizeof(ino)) * 8;
  	return ino;
  }

  static 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));

  	nfs_zap_acl_cache(inode);

  	nfs_access_zap_cache(inode);

  	nfs_fscache_release_inode_cookie(inode);

  }

  void nfs_evict_inode(struct inode *inode)
  {
  	truncate_inode_pages(&inode->i_data, 0);
  	end_writeback(inode);
  	nfs_clear_inode(inode);
  }

  /**
   * nfs_sync_mapping - helper to flush all mmapped dirty data to disk
   */
  int nfs_sync_mapping(struct address_space *mapping)
  {

  	int ret = 0;

  	if (mapping->nrpages != 0) {
  		unmap_mapping_range(mapping, 0, 0, 0);
  		ret = nfs_wb_all(mapping->host);
  	}

  	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);

  	nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
  	nfsi->attrtimeo_timestamp = 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);
  	}
  }

  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);

  }

  void nfs_invalidate_atime(struct inode *inode)
  {
  	spin_lock(&inode->i_lock);
  	NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATIME;
  	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_I(inode)->flags);

  	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;

  	set_nfs_fileid(inode, fattr->fileid);

  	nfs_copy_fh(NFS_FH(inode), desc->fh);
  	return 0;
  }

  /*
   * 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;

  	nfs_attr_check_mountpoint(sb, fattr);

  	if (((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0) &&
  	    !nfs_attr_use_mounted_on_fileid(fattr))

  		goto out_no_inode;

  	if ((fattr->valid & NFS_ATTR_FATTR_TYPE) == 0)

  		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;

  		if ((fattr->valid & NFS_ATTR_FATTR_MODE) == 0
  				&& nfs_server_capable(inode, NFS_CAP_MODE))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL;

  		/* 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_SB(sb)->nfs_client->rpc_ops->file_ops;

  			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;

  			inode->i_data.a_ops = &nfs_dir_aops;

  			if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS))

  				set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);

  			/* Deal with crossing mountpoints */

  			if (fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT ||
  					fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {

  				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;

  				inode->i_flags |= S_AUTOMOUNT;

  			}

  		} else if (S_ISLNK(inode->i_mode))
  			inode->i_op = &nfs_symlink_inode_operations;
  		else
  			init_special_inode(inode, inode->i_mode, fattr->rdev);

  		memset(&inode->i_atime, 0, sizeof(inode->i_atime));
  		memset(&inode->i_mtime, 0, sizeof(inode->i_mtime));
  		memset(&inode->i_ctime, 0, sizeof(inode->i_ctime));

  		inode->i_version = 0;

  		inode->i_size = 0;

  		clear_nlink(inode);

  		inode->i_uid = -2;
  		inode->i_gid = -2;
  		inode->i_blocks = 0;
  		memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));

  		nfsi->read_cache_jiffies = fattr->time_start;

  		nfsi->attr_gencount = fattr->gencount;

  		if (fattr->valid & NFS_ATTR_FATTR_ATIME)
  			inode->i_atime = fattr->atime;

  		else if (nfs_server_capable(inode, NFS_CAP_ATIME))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR;

  		if (fattr->valid & NFS_ATTR_FATTR_MTIME)
  			inode->i_mtime = fattr->mtime;

  		else if (nfs_server_capable(inode, NFS_CAP_MTIME))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_DATA;

  		if (fattr->valid & NFS_ATTR_FATTR_CTIME)
  			inode->i_ctime = fattr->ctime;

  		else if (nfs_server_capable(inode, NFS_CAP_CTIME))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL;

  		if (fattr->valid & NFS_ATTR_FATTR_CHANGE)

  			inode->i_version = fattr->change_attr;

  		else if (nfs_server_capable(inode, NFS_CAP_CHANGE_ATTR))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_DATA;

  		if (fattr->valid & NFS_ATTR_FATTR_SIZE)
  			inode->i_size = nfs_size_to_loff_t(fattr->size);

  		else
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_DATA
  				| NFS_INO_REVAL_PAGECACHE;

  		if (fattr->valid & NFS_ATTR_FATTR_NLINK)

  			set_nlink(inode, fattr->nlink);

  		else if (nfs_server_capable(inode, NFS_CAP_NLINK))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR;

  		if (fattr->valid & NFS_ATTR_FATTR_OWNER)
  			inode->i_uid = fattr->uid;

  		else if (nfs_server_capable(inode, NFS_CAP_OWNER))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL;

  		if (fattr->valid & NFS_ATTR_FATTR_GROUP)
  			inode->i_gid = fattr->gid;

  		else if (nfs_server_capable(inode, NFS_CAP_OWNER_GROUP))
  			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL;

  		if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
  			inode->i_blocks = fattr->du.nfs2.blocks;
  		if (fattr->valid & NFS_ATTR_FATTR_SPACE_USED) {

  			/*
  			 * report the blocks in 512byte units
  			 */
  			inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);

  		}
  		nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);

  		nfsi->attrtimeo_timestamp = now;

  		nfsi->access_cache = RB_ROOT;

  		nfs_fscache_init_inode_cookie(inode);

  		unlock_new_inode(inode);
  	} else
  		nfs_refresh_inode(inode, fattr);
  	dprintk("NFS: nfs_fhget(%s/%Ld ct=%d)
  ",
  		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
  ", 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|ATTR_FILE)

  
  int
  nfs_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	struct inode *inode = dentry->d_inode;

  	struct nfs_fattr *fattr;
  	int error = -ENOMEM;

  	nfs_inc_stats(inode, NFSIOS_VFSSETATTR);

  	/* skip mode change if it's just for clearing setuid/setgid */
  	if (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
  		attr->ia_valid &= ~ATTR_MODE;

  	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 & ~ATTR_FILE) == 0)

  		return 0;

  	/* Write all dirty data */

  	if (S_ISREG(inode->i_mode))

  		nfs_wb_all(inode);

  
  	fattr = nfs_alloc_fattr();
  	if (fattr == NULL)
  		goto out;

  	/*
  	 * 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_free_fattr(fattr);
  out:

  	return error;
  }
  
  /**

   * nfs_vmtruncate - unmap mappings "freed" by truncate() syscall
   * @inode: inode of the file used
   * @offset: file offset to start truncating
   *
   * This is a copy of the common vmtruncate, but with the locking
   * corrected to take into account the fact that NFS requires
   * inode->i_size to be updated under the inode->i_lock.
   */
  static int nfs_vmtruncate(struct inode * inode, loff_t offset)
  {

  	loff_t oldsize;
  	int err;

  	err = inode_newsize_ok(inode, offset);
  	if (err)
  		goto out;

  	spin_lock(&inode->i_lock);
  	oldsize = inode->i_size;
  	i_size_write(inode, offset);
  	spin_unlock(&inode->i_lock);
  
  	truncate_pagecache(inode, oldsize, offset);
  out:
  	return err;

  }
  
  /**

   * 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) {

  		spin_lock(&inode->i_lock);

  		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;

  		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);

  		nfs_vmtruncate(inode, attr->ia_size);

  	}

  }

  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)) {

  		err = filemap_write_and_wait(inode->i_mapping);
  		if (err)
  			goto out;

  	}

  
  	/*
  	 * 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);

  		stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));

  	}

  out:

  	return err;
  }

  static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
  {
  	atomic_set(&l_ctx->count, 1);
  	l_ctx->lockowner = current->files;
  	l_ctx->pid = current->tgid;
  	INIT_LIST_HEAD(&l_ctx->list);
  }
  
  static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context *ctx)
  {
  	struct nfs_lock_context *pos;
  
  	list_for_each_entry(pos, &ctx->lock_context.list, list) {
  		if (pos->lockowner != current->files)
  			continue;
  		if (pos->pid != current->tgid)
  			continue;
  		atomic_inc(&pos->count);
  		return pos;
  	}
  	return NULL;
  }
  
  struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx)
  {
  	struct nfs_lock_context *res, *new = NULL;

  	struct inode *inode = ctx->dentry->d_inode;

  
  	spin_lock(&inode->i_lock);
  	res = __nfs_find_lock_context(ctx);
  	if (res == NULL) {
  		spin_unlock(&inode->i_lock);
  		new = kmalloc(sizeof(*new), GFP_KERNEL);
  		if (new == NULL)
  			return NULL;
  		nfs_init_lock_context(new);
  		spin_lock(&inode->i_lock);
  		res = __nfs_find_lock_context(ctx);
  		if (res == NULL) {
  			list_add_tail(&new->list, &ctx->lock_context.list);
  			new->open_context = ctx;
  			res = new;
  			new = NULL;
  		}
  	}
  	spin_unlock(&inode->i_lock);
  	kfree(new);
  	return res;
  }
  
  void nfs_put_lock_context(struct nfs_lock_context *l_ctx)
  {
  	struct nfs_open_context *ctx = l_ctx->open_context;

  	struct inode *inode = ctx->dentry->d_inode;

  
  	if (!atomic_dec_and_lock(&l_ctx->count, &inode->i_lock))
  		return;
  	list_del(&l_ctx->list);
  	spin_unlock(&inode->i_lock);
  	kfree(l_ctx);
  }

  /**
   * nfs_close_context - Common close_context() routine NFSv2/v3
   * @ctx: pointer to context
   * @is_sync: is this a synchronous close
   *
   * always ensure that the attributes are up to date if we're mounted
   * with close-to-open semantics
   */
  void nfs_close_context(struct nfs_open_context *ctx, int is_sync)
  {
  	struct inode *inode;
  	struct nfs_server *server;
  
  	if (!(ctx->mode & FMODE_WRITE))
  		return;
  	if (!is_sync)
  		return;

  	inode = ctx->dentry->d_inode;

  	if (!list_empty(&NFS_I(inode)->open_files))
  		return;
  	server = NFS_SERVER(inode);
  	if (server->flags & NFS_MOUNT_NOCTO)
  		return;
  	nfs_revalidate_inode(server, inode);
  }

  struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f_mode)

  {
  	struct nfs_open_context *ctx;

  	struct rpc_cred *cred = rpc_lookup_cred();
  	if (IS_ERR(cred))
  		return ERR_CAST(cred);

  	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);

  	if (!ctx) {
  		put_rpccred(cred);
  		return ERR_PTR(-ENOMEM);

  	}

  	nfs_sb_active(dentry->d_sb);
  	ctx->dentry = dget(dentry);
  	ctx->cred = cred;
  	ctx->state = NULL;
  	ctx->mode = f_mode;
  	ctx->flags = 0;
  	ctx->error = 0;
  	nfs_init_lock_context(&ctx->lock_context);
  	ctx->lock_context.open_context = ctx;
  	INIT_LIST_HEAD(&ctx->list);

  	return ctx;
  }
  
  struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)
  {
  	if (ctx != NULL)

  		atomic_inc(&ctx->lock_context.count);

  	return ctx;
  }

  static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)

  {

  	struct inode *inode = ctx->dentry->d_inode;
  	struct super_block *sb = ctx->dentry->d_sb;

  	if (!list_empty(&ctx->list)) {

  		if (!atomic_dec_and_lock(&ctx->lock_context.count, &inode->i_lock))
  			return;
  		list_del(&ctx->list);
  		spin_unlock(&inode->i_lock);

  	} else if (!atomic_dec_and_test(&ctx->lock_context.count))

  		return;

  	if (inode != NULL)
  		NFS_PROTO(inode)->close_context(ctx, is_sync);

  	if (ctx->cred != NULL)
  		put_rpccred(ctx->cred);

  	dput(ctx->dentry);
  	nfs_sb_deactive(sb);

  	kfree(ctx);
  }

  void put_nfs_open_context(struct nfs_open_context *ctx)
  {
  	__put_nfs_open_context(ctx, 0);
  }

  /*
   * Ensure that mmap has a recent RPC credential for use when writing out
   * shared pages
   */

  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, fmode_t 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 & (FMODE_READ|FMODE_WRITE)) != mode)
  			continue;
  		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 = nfs_file_open_context(filp);

  
  	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, filp->f_flags & O_DIRECT ? 0 : 1);

  	}
  }
  
  /*
   * These allocate and release file read/write context information.
   */
  int nfs_open(struct inode *inode, struct file *filp)
  {
  	struct nfs_open_context *ctx;

  	ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode);
  	if (IS_ERR(ctx))
  		return PTR_ERR(ctx);

  	nfs_file_set_open_context(filp, ctx);
  	put_nfs_open_context(ctx);

  	nfs_fscache_set_inode_cookie(inode, filp);

  	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 = NULL;

  	struct nfs_inode *nfsi = NFS_I(inode);

  
  	dfprintk(PAGECACHE, "NFS: revalidating (%s/%Ld)
  ",
  		inode->i_sb->s_id, (long long)NFS_FILEID(inode));

  	if (is_bad_inode(inode))

  		goto out;

  	if (NFS_STALE(inode))

  		goto out;

  	status = -ENOMEM;
  	fattr = nfs_alloc_fattr();
  	if (fattr == NULL)
  		goto out;

  	nfs_inc_stats(inode, NFSIOS_INODEREVALIDATE);

  	status = NFS_PROTO(inode)->getattr(server, NFS_FH(inode), fattr);

  	if (status != 0) {
  		dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) getattr failed, error=%d
  ",
  			 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_I(inode)->flags);

  		}
  		goto out;
  	}

  	status = nfs_refresh_inode(inode, fattr);

  	if (status) {
  		dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) refresh failed, error=%d
  ",
  			 inode->i_sb->s_id,
  			 (long long)NFS_FILEID(inode), status);
  		goto out;
  	}

  	if (nfsi->cache_validity & NFS_INO_INVALID_ACL)

  		nfs_zap_acl_cache(inode);

  	dfprintk(PAGECACHE, "NFS: (%s/%Ld) revalidation complete
  ",
  		inode->i_sb->s_id,
  		(long long)NFS_FILEID(inode));

   out:

  	nfs_free_fattr(fattr);

  	return status;
  }
  
  int nfs_attribute_timeout(struct inode *inode)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);

  	return !time_in_range_open(jiffies, nfsi->read_cache_jiffies, nfsi->read_cache_jiffies + nfsi->attrtimeo);
  }
  
  static int nfs_attribute_cache_expired(struct inode *inode)
  {

  	if (nfs_have_delegated_attributes(inode))

  		return 0;

  	return nfs_attribute_timeout(inode);

  }
  
  /**
   * 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_cache_expired(inode))

  		return NFS_STALE(inode) ? -ESTALE : 0;
  	return __nfs_revalidate_inode(server, inode);
  }

  static int nfs_invalidate_mapping(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));

  	spin_unlock(&inode->i_lock);
  	nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);

  	nfs_fscache_reset_inode_cookie(inode);

  	dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated
  ",
  			inode->i_sb->s_id, (long long)NFS_FILEID(inode));
  	return 0;
  }

  /**
   * nfs_revalidate_mapping - Revalidate the pagecache
   * @inode - pointer to host inode
   * @mapping - pointer to mapping

   */
  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_cache_expired(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;

  }

  static unsigned long nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)

  {
  	struct nfs_inode *nfsi = NFS_I(inode);

  	unsigned long ret = 0;

  	if ((fattr->valid & NFS_ATTR_FATTR_PRECHANGE)
  			&& (fattr->valid & NFS_ATTR_FATTR_CHANGE)

  			&& inode->i_version == fattr->pre_change_attr) {
  		inode->i_version = fattr->change_attr;

  		if (S_ISDIR(inode->i_mode))
  			nfsi->cache_validity |= NFS_INO_INVALID_DATA;

  		ret |= NFS_INO_INVALID_ATTR;

  	}

  	/* If we have atomic WCC data, we may update some attributes */

  	if ((fattr->valid & NFS_ATTR_FATTR_PRECTIME)
  			&& (fattr->valid & NFS_ATTR_FATTR_CTIME)

  			&& timespec_equal(&inode->i_ctime, &fattr->pre_ctime)) {
  		memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
  		ret |= NFS_INO_INVALID_ATTR;
  	}

  
  	if ((fattr->valid & NFS_ATTR_FATTR_PREMTIME)
  			&& (fattr->valid & NFS_ATTR_FATTR_MTIME)
  			&& timespec_equal(&inode->i_mtime, &fattr->pre_mtime)) {

  		memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
  		if (S_ISDIR(inode->i_mode))
  			nfsi->cache_validity |= NFS_INO_INVALID_DATA;
  		ret |= NFS_INO_INVALID_ATTR;

  	}

  	if ((fattr->valid & NFS_ATTR_FATTR_PRESIZE)
  			&& (fattr->valid & NFS_ATTR_FATTR_SIZE)
  			&& i_size_read(inode) == nfs_size_to_loff_t(fattr->pre_size)

  			&& nfsi->npages == 0) {
  		i_size_write(inode, nfs_size_to_loff_t(fattr->size));
  		ret |= NFS_INO_INVALID_ATTR;
  	}
  	return ret;

  }

  /**

   * 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;

  	unsigned long invalid = 0;

  	/* Has the inode gone and changed behind our back? */

  	if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid)
  		return -EIO;
  	if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))

  		return -EIO;

  	if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) != 0 &&

  			inode->i_version != fattr->change_attr)

  		invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;

  	/* Verify a few of the more important attributes */

  	if ((fattr->valid & NFS_ATTR_FATTR_MTIME) && !timespec_equal(&inode->i_mtime, &fattr->mtime))

  		invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;

  	if (fattr->valid & NFS_ATTR_FATTR_SIZE) {
  		cur_size = i_size_read(inode);
  		new_isize = nfs_size_to_loff_t(fattr->size);
  		if (cur_size != new_isize && nfsi->npages == 0)
  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
  	}

  
  	/* Have any file permissions changed? */

  	if ((fattr->valid & NFS_ATTR_FATTR_MODE) && (inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO))
  		invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
  	if ((fattr->valid & NFS_ATTR_FATTR_OWNER) && inode->i_uid != fattr->uid)
  		invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
  	if ((fattr->valid & NFS_ATTR_FATTR_GROUP) && inode->i_gid != fattr->gid)

  		invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;

  
  	/* Has the link count changed? */

  	if ((fattr->valid & NFS_ATTR_FATTR_NLINK) && inode->i_nlink != fattr->nlink)

  		invalid |= NFS_INO_INVALID_ATTR;

  	if ((fattr->valid & NFS_ATTR_FATTR_ATIME) && !timespec_equal(&inode->i_atime, &fattr->atime))

  		invalid |= NFS_INO_INVALID_ATIME;
  
  	if (invalid != 0)
  		nfsi->cache_validity |= invalid;

  	nfsi->read_cache_jiffies = fattr->time_start;

  	return 0;
  }

  static int nfs_ctime_need_update(const struct inode *inode, const struct nfs_fattr *fattr)

  {

  	if (!(fattr->valid & NFS_ATTR_FATTR_CTIME))
  		return 0;

  	return timespec_compare(&fattr->ctime, &inode->i_ctime) > 0;
  }
  
  static int nfs_size_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
  {

  	if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
  		return 0;

  	return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
  }

  static atomic_long_t nfs_attr_generation_counter;

  
  static unsigned long nfs_read_attr_generation_counter(void)
  {

  	return atomic_long_read(&nfs_attr_generation_counter);

  }
  
  unsigned long nfs_inc_attr_generation_counter(void)
  {

  	return atomic_long_inc_return(&nfs_attr_generation_counter);

  }
  
  void nfs_fattr_init(struct nfs_fattr *fattr)
  {
  	fattr->valid = 0;
  	fattr->time_start = jiffies;
  	fattr->gencount = nfs_inc_attr_generation_counter();

  	fattr->owner_name = NULL;
  	fattr->group_name = NULL;

  }

  struct nfs_fattr *nfs_alloc_fattr(void)
  {
  	struct nfs_fattr *fattr;
  
  	fattr = kmalloc(sizeof(*fattr), GFP_NOFS);
  	if (fattr != NULL)
  		nfs_fattr_init(fattr);
  	return fattr;
  }
  
  struct nfs_fh *nfs_alloc_fhandle(void)
  {
  	struct nfs_fh *fh;
  
  	fh = kmalloc(sizeof(struct nfs_fh), GFP_NOFS);
  	if (fh != NULL)
  		fh->size = 0;
  	return fh;
  }

  /**
   * nfs_inode_attrs_need_update - check if the inode attributes need updating
   * @inode - pointer to inode
   * @fattr - attributes
   *
   * Attempt to divine whether or not an RPC call reply carrying stale
   * attributes got scheduled after another call carrying updated ones.
   *
   * To do so, the function first assumes that a more recent ctime means
   * that the attributes in fattr are newer, however it also attempt to
   * catch the case where ctime either didn't change, or went backwards
   * (if someone reset the clock on the server) by looking at whether
   * or not this RPC call was started after the inode was last updated.

   * Note also the check for wraparound of 'attr_gencount'

   *
   * The function returns 'true' if it thinks the attributes in 'fattr' are
   * more recent than the ones cached in the inode.
   *
   */
  static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
  {
  	const struct nfs_inode *nfsi = NFS_I(inode);

  	return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||

  		nfs_ctime_need_update(inode, fattr) ||
  		nfs_size_need_update(inode, fattr) ||

  		((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);

  }
  
  static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
  {
  	if (nfs_inode_attrs_need_update(inode, fattr))

  		return nfs_update_inode(inode, fattr);
  	return nfs_check_inode_attributes(inode, fattr);
  }

  /**
   * 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)
  {

  	int status;
  
  	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
  		return 0;
  	spin_lock(&inode->i_lock);

  	status = nfs_refresh_inode_locked(inode, fattr);

  	spin_unlock(&inode->i_lock);

  	return status;
  }

  static int nfs_post_op_update_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  
  	nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
  	if (S_ISDIR(inode->i_mode))
  		nfsi->cache_validity |= NFS_INO_INVALID_DATA;
  	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
  		return 0;
  	return nfs_refresh_inode_locked(inode, fattr);
  }

  /**
   * 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)
  {

  	int status;

  	spin_lock(&inode->i_lock);

  	status = nfs_post_op_update_inode_locked(inode, fattr);

  	spin_unlock(&inode->i_lock);

  	return status;

  }

  /**
   * nfs_post_op_update_inode_force_wcc - 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. Fake up
   * weak cache consistency data, if none exist.
   *
   * This function is mainly designed to be used by the ->write_done() functions.
   */
  int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr)
  {

  	int status;
  
  	spin_lock(&inode->i_lock);
  	/* Don't do a WCC update if these attributes are already stale */
  	if ((fattr->valid & NFS_ATTR_FATTR) == 0 ||
  			!nfs_inode_attrs_need_update(inode, fattr)) {

  		fattr->valid &= ~(NFS_ATTR_FATTR_PRECHANGE
  				| NFS_ATTR_FATTR_PRESIZE
  				| NFS_ATTR_FATTR_PREMTIME
  				| NFS_ATTR_FATTR_PRECTIME);

  		goto out_noforce;
  	}

  	if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) != 0 &&
  			(fattr->valid & NFS_ATTR_FATTR_PRECHANGE) == 0) {

  		fattr->pre_change_attr = inode->i_version;

  		fattr->valid |= NFS_ATTR_FATTR_PRECHANGE;

  	}

  	if ((fattr->valid & NFS_ATTR_FATTR_CTIME) != 0 &&
  			(fattr->valid & NFS_ATTR_FATTR_PRECTIME) == 0) {

  		memcpy(&fattr->pre_ctime, &inode->i_ctime, sizeof(fattr->pre_ctime));

  		fattr->valid |= NFS_ATTR_FATTR_PRECTIME;
  	}
  	if ((fattr->valid & NFS_ATTR_FATTR_MTIME) != 0 &&
  			(fattr->valid & NFS_ATTR_FATTR_PREMTIME) == 0) {

  		memcpy(&fattr->pre_mtime, &inode->i_mtime, sizeof(fattr->pre_mtime));

  		fattr->valid |= NFS_ATTR_FATTR_PREMTIME;
  	}
  	if ((fattr->valid & NFS_ATTR_FATTR_SIZE) != 0 &&
  			(fattr->valid & NFS_ATTR_FATTR_PRESIZE) == 0) {

  		fattr->pre_size = i_size_read(inode);

  		fattr->valid |= NFS_ATTR_FATTR_PRESIZE;

  	}

  out_noforce:
  	status = nfs_post_op_update_inode_locked(inode, fattr);
  	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 long invalid = 0;

  	unsigned long now = jiffies;

  	unsigned long save_cache_validity;

  
  	dfprintk(VFS, "NFS: %s(%s/%ld ct=%d info=0x%x)
  ",

  			__func__, inode->i_sb->s_id, inode->i_ino,

  			atomic_read(&inode->i_count), fattr->valid);

  	if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid)

  		goto out_fileid;

  
  	/*
  	 * Make sure the inode's type hasn't changed.
  	 */

  	if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))

  		goto out_changed;

  	server = NFS_SERVER(inode);

  	/* Update the fsid? */

  	if (S_ISDIR(inode->i_mode) && (fattr->valid & NFS_ATTR_FATTR_FSID) &&

  			!nfs_fsid_equal(&server->fsid, &fattr->fsid) &&

  			!IS_AUTOMOUNT(inode))

  		server->fsid = fattr->fsid;

  	/*
  	 * Update the read time so we don't revalidate too often.
  	 */

  	nfsi->read_cache_jiffies = fattr->time_start;

  	save_cache_validity = nfsi->cache_validity;
  	nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR
  			| NFS_INO_INVALID_ATIME
  			| NFS_INO_REVAL_FORCED
  			| NFS_INO_REVAL_PAGECACHE);

  	/* Do atomic weak cache consistency updates */

  	invalid |= nfs_wcc_update_inode(inode, fattr);

  	/* More cache consistency checks */

  	if (fattr->valid & NFS_ATTR_FATTR_CHANGE) {

  		if (inode->i_version != fattr->change_attr) {

  			dprintk("NFS: change_attr change on server for file %s/%ld
  ",
  					inode->i_sb->s_id, inode->i_ino);
  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  			if (S_ISDIR(inode->i_mode))
  				nfs_force_lookup_revalidate(inode);

  			inode->i_version = fattr->change_attr;

  		}

  	} else if (server->caps & NFS_CAP_CHANGE_ATTR)
  		invalid |= save_cache_validity;

  
  	if (fattr->valid & NFS_ATTR_FATTR_MTIME) {

  		/* NFSv2/v3: Check if the mtime agrees */
  		if (!timespec_equal(&inode->i_mtime, &fattr->mtime)) {
  			dprintk("NFS: mtime change on server for file %s/%ld
  ",
  					inode->i_sb->s_id, inode->i_ino);
  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;

  			if (S_ISDIR(inode->i_mode))
  				nfs_force_lookup_revalidate(inode);

  			memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));

  		}

  	} else if (server->caps & NFS_CAP_MTIME)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_DATA
  				| NFS_INO_REVAL_PAGECACHE
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_CTIME) {

  		/* If ctime has changed we should definitely clear access+acl caches */

  		if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) {

  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;

  			/* and probably clear data for a directory too as utimes can cause
  			 * havoc with our cache.
  			 */
  			if (S_ISDIR(inode->i_mode)) {
  				invalid |= NFS_INO_INVALID_DATA;
  				nfs_force_lookup_revalidate(inode);
  			}

  			memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));

  		}

  	} else if (server->caps & NFS_CAP_CTIME)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL
  				| NFS_INO_REVAL_FORCED);

  	/* Check if our cached file size is stale */

  	if (fattr->valid & NFS_ATTR_FATTR_SIZE) {
  		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, or has
  			 * the file grown beyond our last write? */

  			if ((nfsi->npages == 0 && !test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) ||
  			     new_isize > cur_isize) {

  				i_size_write(inode, new_isize);
  				invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
  			}

  			dprintk("NFS: isize change on server for file %s/%ld "
  					"(%Ld to %Ld)
  ",
  					inode->i_sb->s_id,
  					inode->i_ino,
  					(long long)cur_isize,
  					(long long)new_isize);

  		}

  	} else
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_REVAL_PAGECACHE
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_ATIME)
  		memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));

  	else if (server->caps & NFS_CAP_ATIME)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATIME
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_MODE) {
  		if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO)) {

  			umode_t newmode = inode->i_mode & S_IFMT;
  			newmode |= fattr->mode & S_IALLUGO;
  			inode->i_mode = newmode;

  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;

  		}

  	} else if (server->caps & NFS_CAP_MODE)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_OWNER) {
  		if (inode->i_uid != fattr->uid) {
  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  			inode->i_uid = fattr->uid;
  		}

  	} else if (server->caps & NFS_CAP_OWNER)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_GROUP) {
  		if (inode->i_gid != fattr->gid) {
  			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
  			inode->i_gid = fattr->gid;
  		}

  	} else if (server->caps & NFS_CAP_OWNER_GROUP)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_INVALID_ACCESS
  				| NFS_INO_INVALID_ACL
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_NLINK) {
  		if (inode->i_nlink != fattr->nlink) {
  			invalid |= NFS_INO_INVALID_ATTR;
  			if (S_ISDIR(inode->i_mode))
  				invalid |= NFS_INO_INVALID_DATA;

  			set_nlink(inode, fattr->nlink);

  		}

  	} else if (server->caps & NFS_CAP_NLINK)
  		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
  				| NFS_INO_REVAL_FORCED);

  	if (fattr->valid & NFS_ATTR_FATTR_SPACE_USED) {

  		/*
  		 * report the blocks in 512byte units
  		 */
  		inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);

   	}

  	if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
  		inode->i_blocks = fattr->du.nfs2.blocks;

  
  	/* 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;

  		nfsi->attr_gencount = nfs_inc_attr_generation_counter();

  	} else {

  		if (!time_in_range_open(now, nfsi->attrtimeo_timestamp, nfsi->attrtimeo_timestamp + nfsi->attrtimeo)) {

  			if ((nfsi->attrtimeo <<= 1) > NFS_MAXATTRTIMEO(inode))
  				nfsi->attrtimeo = NFS_MAXATTRTIMEO(inode);
  			nfsi->attrtimeo_timestamp = now;
  		}

  	}

  	invalid &= ~NFS_INO_INVALID_ATTR;

  	/* 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 (!nfs_have_delegation(inode, FMODE_READ) ||

  			(save_cache_validity & NFS_INO_REVAL_FORCED))

  		nfsi->cache_validity |= invalid;

  
  	return 0;
   out_changed:
  	/*
  	 * Big trouble! The inode has become a different object.
  	 */

  	printk(KERN_DEBUG "%s: inode %ld mode changed, %07o to %07o
  ",

  			__func__, inode->i_ino, inode->i_mode, fattr->mode);

   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
  "
  		"fsid %s: expected fileid 0x%Lx, got 0x%Lx
  ",

  		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_evict_inode(struct inode *inode)

  {

  	truncate_inode_pages(&inode->i_data, 0);
  	end_writeback(inode);

  	pnfs_return_layout(inode);
  	pnfs_destroy_layout(NFS_I(inode));

  	/* If we are holding a delegation, return it! */

  	nfs_inode_return_delegation_noreclaim(inode);

  	/* First call standard NFS clear_inode() code */
  	nfs_clear_inode(inode);

  }

  #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;
  }

  static void nfs_i_callback(struct rcu_head *head)

  {

  	struct inode *inode = container_of(head, struct inode, i_rcu);

  	kmem_cache_free(nfs_inode_cachep, NFS_I(inode));
  }

  void nfs_destroy_inode(struct inode *inode)
  {
  	call_rcu(&inode->i_rcu, nfs_i_callback);
  }

  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);

  	nfsi->layout = NULL;

  	atomic_set(&nfsi->commits_outstanding, 0);

  #endif
  }

  static void init_once(void *foo)

  {
  	struct nfs_inode *nfsi = (struct nfs_inode *) foo;

  	inode_init_once(&nfsi->vfs_inode);

  	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);

  	nfsi->npages = 0;

  	nfsi->ncommit = 0;

  	atomic_set(&nfsi->silly_count, 1);
  	INIT_HLIST_HEAD(&nfsi->silly_list);
  	init_waitqueue_head(&nfsi->waitqueue);

  	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);

  	if (nfs_inode_cachep == NULL)
  		return -ENOMEM;
  
  	return 0;
  }

  static void nfs_destroy_inodecache(void)

  {

  	kmem_cache_destroy(nfs_inode_cachep);

  }

  struct workqueue_struct *nfsiod_workqueue;
  
  /*
   * start up the nfsiod workqueue
   */
  static int nfsiod_start(void)
  {
  	struct workqueue_struct *wq;
  	dprintk("RPC:       creating workqueue nfsiod
  ");

  	wq = alloc_workqueue("nfsiod", WQ_MEM_RECLAIM, 0);

  	if (wq == NULL)
  		return -ENOMEM;
  	nfsiod_workqueue = wq;
  	return 0;
  }
  
  /*
   * Destroy the nfsiod workqueue
   */
  static void nfsiod_stop(void)
  {
  	struct workqueue_struct *wq;
  
  	wq = nfsiod_workqueue;
  	if (wq == NULL)
  		return;
  	nfsiod_workqueue = NULL;
  	destroy_workqueue(wq);
  }

  /*
   * Initialize NFS
   */
  static int __init init_nfs_fs(void)
  {
  	int err;

  	err = nfs_idmap_init();
  	if (err < 0)
  		goto out9;

  	err = nfs_dns_resolver_init();
  	if (err < 0)
  		goto out8;

  	err = nfs_fscache_register();
  	if (err < 0)
  		goto out7;

  	err = nfsiod_start();
  	if (err)
  		goto out6;

  	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:

  	nfsiod_stop();
  out6:

  	nfs_fscache_unregister();
  out7:

  	nfs_dns_resolver_destroy();
  out8:

  	nfs_idmap_quit();
  out9:

  	return err;
  }
  
  static void __exit exit_nfs_fs(void)
  {

  	nfs_destroy_directcache();

  	nfs_destroy_writepagecache();
  	nfs_destroy_readpagecache();
  	nfs_destroy_inodecache();
  	nfs_destroy_nfspagecache();

  	nfs_fscache_unregister();

  	nfs_dns_resolver_destroy();

  	nfs_idmap_quit();

  #ifdef CONFIG_PROC_FS
  	rpc_proc_unregister("nfs");
  #endif

  	nfs_cleanup_cb_ident_idr();

  	unregister_nfs_fs();

  	nfs_fs_proc_exit();

  	nfsiod_stop();

  }
  
  /* Not quite true; I just maintain it */
  MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
  MODULE_LICENSE("GPL");

  module_param(enable_ino64, bool, 0644);

  
  module_init(init_nfs_fs)
  module_exit(exit_nfs_fs)