/*
 *  linux/fs/9p/vfs_inode.c
 *
 * This file contains vfs inode ops for the 9P2000 protocol.
 *
 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
 *
 *  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.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/inet.h>
#include <linux/namei.h>
#include <linux/idr.h>

#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "v9fs_vfs.h"
#include "conv.h"
#include "fid.h"

static struct inode_operations v9fs_dir_inode_operations;
static struct inode_operations v9fs_file_inode_operations;
static struct inode_operations v9fs_symlink_inode_operations;

/**
 * unixmode2p9mode - convert unix mode bits to plan 9
 * @v9ses: v9fs session information
 * @mode: mode to convert
 *
 */

static int unixmode2p9mode(struct v9fs_session_info *v9ses, int mode)
{
	int res;
	res = mode & 0777;
	if (S_ISDIR(mode))
		res |= V9FS_DMDIR;
	if (v9ses->extended) {
		if (S_ISLNK(mode))
			res |= V9FS_DMSYMLINK;
		if (v9ses->nodev == 0) {
			if (S_ISSOCK(mode))
				res |= V9FS_DMSOCKET;
			if (S_ISFIFO(mode))
				res |= V9FS_DMNAMEDPIPE;
			if (S_ISBLK(mode))
				res |= V9FS_DMDEVICE;
			if (S_ISCHR(mode))
				res |= V9FS_DMDEVICE;
		}

		if ((mode & S_ISUID) == S_ISUID)
			res |= V9FS_DMSETUID;
		if ((mode & S_ISGID) == S_ISGID)
			res |= V9FS_DMSETGID;
		if ((mode & V9FS_DMLINK))
			res |= V9FS_DMLINK;
	}

	return res;
}

/**
 * p9mode2unixmode- convert plan9 mode bits to unix mode bits
 * @v9ses: v9fs session information
 * @mode: mode to convert
 *
 */

static int p9mode2unixmode(struct v9fs_session_info *v9ses, int mode)
{
	int res;

	res = mode & 0777;

	if ((mode & V9FS_DMDIR) == V9FS_DMDIR)
		res |= S_IFDIR;
	else if ((mode & V9FS_DMSYMLINK) && (v9ses->extended))
		res |= S_IFLNK;
	else if ((mode & V9FS_DMSOCKET) && (v9ses->extended)
		 && (v9ses->nodev == 0))
		res |= S_IFSOCK;
	else if ((mode & V9FS_DMNAMEDPIPE) && (v9ses->extended)
		 && (v9ses->nodev == 0))
		res |= S_IFIFO;
	else if ((mode & V9FS_DMDEVICE) && (v9ses->extended)
		 && (v9ses->nodev == 0))
		res |= S_IFBLK;
	else
		res |= S_IFREG;

	if (v9ses->extended) {
		if ((mode & V9FS_DMSETUID) == V9FS_DMSETUID)
			res |= S_ISUID;

		if ((mode & V9FS_DMSETGID) == V9FS_DMSETGID)
			res |= S_ISGID;
	}

	return res;
}

/**
 * v9fs_blank_mistat - helper function to setup a 9P stat structure
 * @v9ses: 9P session info (for determining extended mode)
 * @mistat: structure to initialize
 *
 */

static void
v9fs_blank_mistat(struct v9fs_session_info *v9ses, struct v9fs_stat *mistat)
{
	mistat->type = ~0;
	mistat->dev = ~0;
	mistat->qid.type = ~0;
	mistat->qid.version = ~0;
	*((long long *)&mistat->qid.path) = ~0;
	mistat->mode = ~0;
	mistat->atime = ~0;
	mistat->mtime = ~0;
	mistat->length = ~0;
	mistat->name = mistat->data;
	mistat->uid = mistat->data;
	mistat->gid = mistat->data;
	mistat->muid = mistat->data;
	if (v9ses->extended) {
		mistat->n_uid = ~0;
		mistat->n_gid = ~0;
		mistat->n_muid = ~0;
		mistat->extension = mistat->data;
	}
	*mistat->data = 0;
}

/**
 * v9fs_mistat2unix - convert mistat to unix stat
 * @mistat: Plan 9 metadata (mistat) structure
 * @buf: unix metadata (stat) structure to populate
 * @sb: superblock
 *
 */

static void
v9fs_mistat2unix(struct v9fs_stat *mistat, struct stat *buf,
		 struct super_block *sb)
{
	struct v9fs_session_info *v9ses = sb ? sb->s_fs_info : NULL;

	buf->st_nlink = 1;

	buf->st_atime = mistat->atime;
	buf->st_mtime = mistat->mtime;
	buf->st_ctime = mistat->mtime;

	buf->st_uid = (unsigned short)-1;
	buf->st_gid = (unsigned short)-1;

	if (v9ses && v9ses->extended) {
		/* TODO: string to uid mapping via user-space daemon */
		if (mistat->n_uid != -1)
			sscanf(mistat->uid, "%x", (unsigned int *)&buf->st_uid);

		if (mistat->n_gid != -1)
			sscanf(mistat->gid, "%x", (unsigned int *)&buf->st_gid);
	}

	if (buf->st_uid == (unsigned short)-1)
		buf->st_uid = v9ses->uid;
	if (buf->st_gid == (unsigned short)-1)
		buf->st_gid = v9ses->gid;

	buf->st_mode = p9mode2unixmode(v9ses, mistat->mode);
	if ((S_ISBLK(buf->st_mode)) || (S_ISCHR(buf->st_mode))) {
		char type = 0;
		int major = -1;
		int minor = -1;
		sscanf(mistat->extension, "%c %u %u", &type, &major, &minor);
		switch (type) {
		case 'c':
			buf->st_mode &= ~S_IFBLK;
			buf->st_mode |= S_IFCHR;
			break;
		case 'b':
			break;
		default:
			dprintk(DEBUG_ERROR, "Unknown special type %c (%s)\n",
				type, mistat->extension);
		};
		buf->st_rdev = MKDEV(major, minor);
	} else
		buf->st_rdev = 0;

	buf->st_size = mistat->length;

	buf->st_blksize = sb->s_blocksize;
	buf->st_blocks =
	    (buf->st_size + buf->st_blksize - 1) >> sb->s_blocksize_bits;
}

/**
 * v9fs_get_inode - helper function to setup an inode
 * @sb: superblock
 * @mode: mode to setup inode with
 *
 */

struct inode *v9fs_get_inode(struct super_block *sb, int mode)
{
	struct inode *inode = NULL;

	dprintk(DEBUG_VFS, "super block: %p mode: %o\n", sb, mode);

	inode = new_inode(sb);
	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = current->fsuid;
		inode->i_gid = current->fsgid;
		inode->i_blksize = sb->s_blocksize;
		inode->i_blocks = 0;
		inode->i_rdev = 0;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;

		switch (mode & S_IFMT) {
		case S_IFIFO:
		case S_IFBLK:
		case S_IFCHR:
		case S_IFSOCK:
			init_special_inode(inode, inode->i_mode,
					   inode->i_rdev);
			break;
		case S_IFREG:
			inode->i_op = &v9fs_file_inode_operations;
			inode->i_fop = &v9fs_file_operations;
			break;
		case S_IFDIR:
			inode->i_nlink++;
			inode->i_op = &v9fs_dir_inode_operations;
			inode->i_fop = &v9fs_dir_operations;
			break;
		case S_IFLNK:
			inode->i_op = &v9fs_symlink_inode_operations;
			break;
		default:
			dprintk(DEBUG_ERROR, "BAD mode 0x%x S_IFMT 0x%x\n",
				mode, mode & S_IFMT);
			return ERR_PTR(-EINVAL);
		}
	} else {
		eprintk(KERN_WARNING, "Problem allocating inode\n");
		return ERR_PTR(-ENOMEM);
	}
	return inode;
}

/**
 * v9fs_create - helper function to create files and directories
 * @dir: directory inode file is being created in
 * @file_dentry: dentry file is being created in
 * @perm: permissions file is being created with
 * @open_mode: resulting open mode for file
 *
 */

static int
v9fs_create(struct inode *dir,
	    struct dentry *file_dentry,
	    unsigned int perm, unsigned int open_mode)
{
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
	struct super_block *sb = dir->i_sb;
	struct v9fs_fid *dirfid =
	    v9fs_fid_lookup(file_dentry->d_parent, FID_WALK);
	struct v9fs_fid *fid = NULL;
	struct inode *file_inode = NULL;
	struct v9fs_fcall *fcall = NULL;
	struct v9fs_qid qid;
	struct stat newstat;
	int dirfidnum = -1;
	long newfid = -1;
	int result = 0;
	unsigned int iounit = 0;

	perm = unixmode2p9mode(v9ses, perm);

	dprintk(DEBUG_VFS, "dir: %p dentry: %p perm: %o mode: %o\n", dir,
		file_dentry, perm, open_mode);

	if (!dirfid)
		return -EBADF;

	dirfidnum = dirfid->fid;
	if (dirfidnum < 0) {
		dprintk(DEBUG_ERROR, "No fid for the directory #%lu\n",
			dir->i_ino);
		return -EBADF;
	}

	if (file_dentry->d_inode) {
		dprintk(DEBUG_ERROR,
			"Odd. There is an inode for dir %lu, name :%s:\n",
			dir->i_ino, file_dentry->d_name.name);
		return -EEXIST;
	}

	newfid = v9fs_get_idpool(&v9ses->fidpool);
	if (newfid < 0) {
		eprintk(KERN_WARNING, "no free fids available\n");
		return -ENOSPC;
	}

	result = v9fs_t_walk(v9ses, dirfidnum, newfid, NULL, &fcall);
	if (result < 0) {
		dprintk(DEBUG_ERROR, "clone error: %s\n", FCALL_ERROR(fcall));
		v9fs_put_idpool(newfid, &v9ses->fidpool);
		newfid = 0;
		goto CleanUpFid;
	}

	kfree(fcall);

	result = v9fs_t_create(v9ses, newfid, (char *)file_dentry->d_name.name,
			       perm, open_mode, &fcall);
	if (result < 0) {
		dprintk(DEBUG_ERROR, "create fails: %s(%d)\n",
			FCALL_ERROR(fcall), result);

		goto CleanUpFid;
	}

	iounit = fcall->params.rcreate.iounit;
	qid = fcall->params.rcreate.qid;
	kfree(fcall);

	fid = v9fs_fid_create(file_dentry);
	if (!fid) {
		result = -ENOMEM;
		goto CleanUpFid;
	}

	fid->fid = newfid;
	fid->fidopen = 0;
	fid->fidcreate = 1;
	fid->qid = qid;
	fid->iounit = iounit;
	fid->rdir_pos = 0;
	fid->rdir_fcall = NULL;
	fid->v9ses = v9ses;

	if ((perm & V9FS_DMSYMLINK) || (perm & V9FS_DMLINK) ||
	    (perm & V9FS_DMNAMEDPIPE) || (perm & V9FS_DMSOCKET) ||
	    (perm & V9FS_DMDEVICE))
		return 0;

	result = v9fs_t_stat(v9ses, newfid, &fcall);
	if (result < 0) {
		dprintk(DEBUG_ERROR, "stat error: %s(%d)\n", FCALL_ERROR(fcall),
			result);
		goto CleanUpFid;
	}

	v9fs_mistat2unix(fcall->params.rstat.stat, &newstat, sb);

	file_inode = v9fs_get_inode(sb, newstat.st_mode);
	if ((!file_inode) || IS_ERR(file_inode)) {
		dprintk(DEBUG_ERROR, "create inode failed\n");
		result = -EBADF;
		goto CleanUpFid;
	}

	v9fs_mistat2inode(fcall->params.rstat.stat, file_inode, sb);
	kfree(fcall);
	d_instantiate(file_dentry, file_inode);

	if (perm & V9FS_DMDIR) {
		if (v9fs_t_clunk(v9ses, newfid, &fcall))
			dprintk(DEBUG_ERROR, "clunk for mkdir failed: %s\n",
				FCALL_ERROR(fcall));

		v9fs_put_idpool(newfid, &v9ses->fidpool);
		kfree(fcall);
		fid->fidopen = 0;
		fid->fidcreate = 0;
		d_drop(file_dentry);
	}

	return 0;

      CleanUpFid:
	kfree(fcall);

	if (newfid) {
		if (v9fs_t_clunk(v9ses, newfid, &fcall))
			dprintk(DEBUG_ERROR, "clunk failed: %s\n",
				FCALL_ERROR(fcall));

		v9fs_put_idpool(newfid, &v9ses->fidpool);
		kfree(fcall);
	}
	return result;
}

/**
 * v9fs_remove - helper function to remove files and directories
 * @dir: directory inode that is being deleted
 * @file:  dentry that is being deleted
 * @rmdir: removing a directory
 *
 */

static int v9fs_remove(struct inode *dir, struct dentry *file, int rmdir)
{
	struct v9fs_fcall *fcall = NULL;
	struct super_block *sb = NULL;
	struct v9fs_session_info *v9ses = NULL;
	struct v9fs_fid *v9fid = NULL;
	struct inode *file_inode = NULL;
	int fid = -1;
	int result = 0;

	dprintk(DEBUG_VFS, "inode: %p dentry: %p rmdir: %d\n", dir, file,
		rmdir);

	file_inode = file->d_inode;
	sb = file_inode->i_sb;
	v9ses = v9fs_inode2v9ses(file_inode);
	v9fid = v9fs_fid_lookup(file, FID_OP);

	if (!v9fid) {
		dprintk(DEBUG_ERROR,
			"no v9fs_fid\n");
		return -EBADF;
	}

	fid = v9fid->fid;
	if (fid < 0) {
		dprintk(DEBUG_ERROR, "inode #%lu, no fid!\n",
			file_inode->i_ino);
		return -EBADF;
	}

	result = v9fs_t_remove(v9ses, fid, &fcall);
	if (result < 0)
		dprintk(DEBUG_ERROR, "remove of file fails: %s(%d)\n",
			FCALL_ERROR(fcall), result);
	else {
		v9fs_put_idpool(fid, &v9ses->fidpool);
		v9fs_fid_destroy(v9fid);
	}

	kfree(fcall);
	return result;
}

/**
 * v9fs_vfs_create - VFS hook to create files
 * @inode: directory inode that is being deleted
 * @dentry:  dentry that is being deleted
 * @perm: create permissions
 * @nd: path information
 *
 */

static int
v9fs_vfs_create(struct inode *inode, struct dentry *dentry, int perm,
		struct nameidata *nd)
{
	return v9fs_create(inode, dentry, perm, O_RDWR);
}

/**
 * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
 * @inode:  inode that is being unlinked
 * @dentry: dentry that is being unlinked
 * @mode: mode for new directory
 *
 */

static int v9fs_vfs_mkdir(struct inode *inode, struct dentry *dentry, int mode)
{
	return v9fs_create(inode, dentry, mode | S_IFDIR, O_RDONLY);
}

/**
 * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
 * @dir:  inode that is being walked from
 * @dentry: dentry that is being walked to?
 * @nameidata: path data
 *
 */

static struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
				      struct nameidata *nameidata)
{
	struct super_block *sb;
	struct v9fs_session_info *v9ses;
	struct v9fs_fid *dirfid;
	struct v9fs_fid *fid;
	struct inode *inode;
	struct v9fs_fcall *fcall = NULL;
	struct stat newstat;
	int dirfidnum = -1;
	int newfid = -1;
	int result = 0;

	dprintk(DEBUG_VFS, "dir: %p dentry: (%s) %p nameidata: %p\n",
		dir, dentry->d_iname, dentry, nameidata);

	sb = dir->i_sb;
	v9ses = v9fs_inode2v9ses(dir);
	dirfid = v9fs_fid_lookup(dentry->d_parent, FID_WALK);

	if (!dirfid) {
		dprintk(DEBUG_ERROR, "no dirfid\n");
		return ERR_PTR(-EINVAL);
	}

	dirfidnum = dirfid->fid;

	if (dirfidnum < 0) {
		dprintk(DEBUG_ERROR, "no dirfid for inode %p, #%lu\n",
			dir, dir->i_ino);
		return ERR_PTR(-EBADF);
	}

	newfid = v9fs_get_idpool(&v9ses->fidpool);
	if (newfid < 0) {
		eprintk(KERN_WARNING, "newfid fails!\n");
		return ERR_PTR(-ENOSPC);
	}

	result =
	    v9fs_t_walk(v9ses, dirfidnum, newfid, (char *)dentry->d_name.name,
			NULL);
	if (result < 0) {
		v9fs_put_idpool(newfid, &v9ses->fidpool);
		if (result == -ENOENT) {
			d_add(dentry, NULL);
			dprintk(DEBUG_ERROR,
				"Return negative dentry %p count %d\n",
				dentry, atomic_read(&dentry->d_count));
			return NULL;
		}
		dprintk(DEBUG_ERROR, "walk error:%d\n", result);
		goto FreeFcall;
	}

	result = v9fs_t_stat(v9ses, newfid, &fcall);
	if (result < 0) {
		dprintk(DEBUG_ERROR, "stat error\n");
		goto FreeFcall;
	}

	v9fs_mistat2unix(fcall->params.rstat.stat, &newstat, sb);
	inode = v9fs_get_inode(sb, newstat.st_mode);

	if (IS_ERR(inode) && (PTR_ERR(inode) == -ENOSPC)) {
		eprintk(KERN_WARNING, "inode alloc failes, returns %ld\n",
			PTR_ERR(inode));

		result = -ENOSPC;
		goto FreeFcall;
	}

	inode->i_ino = v9fs_qid2ino(&fcall->params.rstat.stat->qid);

	fid = v9fs_fid_create(dentry);
	if (fid == NULL) {
		dprintk(DEBUG_ERROR, "couldn't insert\n");
		result = -ENOMEM;
		goto FreeFcall;
	}

	fid->fid = newfid;
	fid->fidopen = 0;
	fid->v9ses = v9ses;
	fid->qid = fcall->params.rstat.stat->qid;

	dentry->d_op = &v9fs_dentry_operations;
	v9fs_mistat2inode(fcall->params.rstat.stat, inode, inode->i_sb);

	d_add(dentry, inode);
	kfree(fcall);

	return NULL;

      FreeFcall:
	kfree(fcall);
	return ERR_PTR(result);
}

/**
 * v9fs_vfs_unlink - VFS unlink hook to delete an inode
 * @i:  inode that is being unlinked
 * @d: dentry that is being unlinked
 *
 */

static int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
{
	return v9fs_remove(i, d, 0);
}

/**
 * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
 * @i:  inode that is being unlinked
 * @d: dentry that is being unlinked
 *
 */

static int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
{
	return v9fs_remove(i, d, 1);
}

/**
 * v9fs_vfs_rename - VFS hook to rename an inode
 * @old_dir:  old dir inode
 * @old_dentry: old dentry
 * @new_dir: new dir inode
 * @new_dentry: new dentry
 *
 */

static int
v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
		struct inode *new_dir, struct dentry *new_dentry)
{
	struct inode *old_inode = old_dentry->d_inode;
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(old_inode);
	struct v9fs_fid *oldfid = v9fs_fid_lookup(old_dentry, FID_WALK);
	struct v9fs_fid *olddirfid =
	    v9fs_fid_lookup(old_dentry->d_parent, FID_WALK);
	struct v9fs_fid *newdirfid =
	    v9fs_fid_lookup(new_dentry->d_parent, FID_WALK);
	struct v9fs_stat *mistat = kmalloc(v9ses->maxdata, GFP_KERNEL);
	struct v9fs_fcall *fcall = NULL;
	int fid = -1;
	int olddirfidnum = -1;
	int newdirfidnum = -1;
	int retval = 0;

	dprintk(DEBUG_VFS, "\n");

	if (!mistat)
		return -ENOMEM;

	if ((!oldfid) || (!olddirfid) || (!newdirfid)) {
		dprintk(DEBUG_ERROR, "problem with arguments\n");
		return -EBADF;
	}

	/* 9P can only handle file rename in the same directory */
	if (memcmp(&olddirfid->qid, &newdirfid->qid, sizeof(newdirfid->qid))) {
		dprintk(DEBUG_ERROR, "old dir and new dir are different\n");
		retval = -EPERM;
		goto FreeFcallnBail;
	}

	fid = oldfid->fid;
	olddirfidnum = olddirfid->fid;
	newdirfidnum = newdirfid->fid;

	if (fid < 0) {
		dprintk(DEBUG_ERROR, "no fid for old file #%lu\n",
			old_inode->i_ino);
		retval = -EBADF;
		goto FreeFcallnBail;
	}

	v9fs_blank_mistat(v9ses, mistat);

	strcpy(mistat->data + 1, v9ses->name);
	mistat->name = mistat->data + 1 + strlen(v9ses->name);

	if (new_dentry->d_name.len >
	    (v9ses->maxdata - strlen(v9ses->name) - sizeof(struct v9fs_stat))) {
		dprintk(DEBUG_ERROR, "new name too long\n");
		goto FreeFcallnBail;
	}

	strcpy(mistat->name, new_dentry->d_name.name);
	retval = v9fs_t_wstat(v9ses, fid, mistat, &fcall);

      FreeFcallnBail:
	kfree(mistat);

	if (retval < 0)
		dprintk(DEBUG_ERROR, "v9fs_t_wstat error: %s\n",
			FCALL_ERROR(fcall));

	kfree(fcall);
	return retval;
}

/**
 * v9fs_vfs_getattr - retreive file metadata
 * @mnt - mount information
 * @dentry - file to get attributes on
 * @stat - metadata structure to populate
 *
 */

static int
v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
		 struct kstat *stat)
{
	struct v9fs_fcall *fcall = NULL;
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dentry->d_inode);
	struct v9fs_fid *fid = v9fs_fid_lookup(dentry, FID_OP);
	int err = -EPERM;

	dprintk(DEBUG_VFS, "dentry: %p\n", dentry);
	if (!fid) {
		dprintk(DEBUG_ERROR,
			"couldn't find fid associated with dentry\n");
		return -EBADF;
	}

	err = v9fs_t_stat(v9ses, fid->fid, &fcall);

	if (err < 0)
		dprintk(DEBUG_ERROR, "stat error\n");
	else {
		v9fs_mistat2inode(fcall->params.rstat.stat, dentry->d_inode,
				  dentry->d_inode->i_sb);
		generic_fillattr(dentry->d_inode, stat);
	}

	kfree(fcall);
	return err;
}

/**
 * v9fs_vfs_setattr - set file metadata
 * @dentry: file whose metadata to set
 * @iattr: metadata assignment structure
 *
 */

static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
{
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dentry->d_inode);
	struct v9fs_fid *fid = v9fs_fid_lookup(dentry, FID_OP);
	struct v9fs_fcall *fcall = NULL;
	struct v9fs_stat *mistat = kmalloc(v9ses->maxdata, GFP_KERNEL);
	int res = -EPERM;

	dprintk(DEBUG_VFS, "\n");

	if (!mistat)
		return -ENOMEM;

	if (!fid) {
		dprintk(DEBUG_ERROR,
			"Couldn't find fid associated with dentry\n");
		return -EBADF;
	}

	v9fs_blank_mistat(v9ses, mistat);
	if (iattr->ia_valid & ATTR_MODE)
		mistat->mode = unixmode2p9mode(v9ses, iattr->ia_mode);

	if (iattr->ia_valid & ATTR_MTIME)
		mistat->mtime = iattr->ia_mtime.tv_sec;

	if (iattr->ia_valid & ATTR_ATIME)
		mistat->atime = iattr->ia_atime.tv_sec;

	if (iattr->ia_valid & ATTR_SIZE)
		mistat->length = iattr->ia_size;

	if (v9ses->extended) {
		char *ptr = mistat->data+1;

		if (iattr->ia_valid & ATTR_UID) {
			mistat->uid = ptr;
			ptr += 1+sprintf(ptr, "%08x", iattr->ia_uid);
			mistat->n_uid = iattr->ia_uid;
		}

		if (iattr->ia_valid & ATTR_GID) {
			mistat->gid = ptr;
			ptr += 1+sprintf(ptr, "%08x", iattr->ia_gid);
			mistat->n_gid = iattr->ia_gid;
		}
	}

	res = v9fs_t_wstat(v9ses, fid->fid, mistat, &fcall);

	if (res < 0)
		dprintk(DEBUG_ERROR, "wstat error: %s\n", FCALL_ERROR(fcall));

	kfree(mistat);
	kfree(fcall);

	if (res >= 0)
		res = inode_setattr(dentry->d_inode, iattr);

	return res;
}

/**
 * v9fs_mistat2inode - populate an inode structure with mistat info
 * @mistat: Plan 9 metadata (mistat) structure
 * @inode: inode to populate
 * @sb: superblock of filesystem
 *
 */

void
v9fs_mistat2inode(struct v9fs_stat *mistat, struct inode *inode,
		  struct super_block *sb)
{
	struct v9fs_session_info *v9ses = sb->s_fs_info;

	inode->i_nlink = 1;

	inode->i_atime.tv_sec = mistat->atime;
	inode->i_mtime.tv_sec = mistat->mtime;
	inode->i_ctime.tv_sec = mistat->mtime;

	inode->i_uid = -1;
	inode->i_gid = -1;

	if (v9ses->extended) {
		/* TODO: string to uid mapping via user-space daemon */
		inode->i_uid = mistat->n_uid;
		inode->i_gid = mistat->n_gid;

		if (mistat->n_uid == -1)
			sscanf(mistat->uid, "%x", &inode->i_uid);

		if (mistat->n_gid == -1)
			sscanf(mistat->gid, "%x", &inode->i_gid);
	}

	if (inode->i_uid == -1)
		inode->i_uid = v9ses->uid;
	if (inode->i_gid == -1)
		inode->i_gid = v9ses->gid;

	inode->i_mode = p9mode2unixmode(v9ses, mistat->mode);
	if ((S_ISBLK(inode->i_mode)) || (S_ISCHR(inode->i_mode))) {
		char type = 0;
		int major = -1;
		int minor = -1;
		sscanf(mistat->extension, "%c %u %u", &type, &major, &minor);
		switch (type) {
		case 'c':
			inode->i_mode &= ~S_IFBLK;
			inode->i_mode |= S_IFCHR;
			break;
		case 'b':
			break;
		default:
			dprintk(DEBUG_ERROR, "Unknown special type %c (%s)\n",
				type, mistat->extension);
		};
		inode->i_rdev = MKDEV(major, minor);
	} else
		inode->i_rdev = 0;

	inode->i_size = mistat->length;

	inode->i_blksize = sb->s_blocksize;
	inode->i_blocks =
	    (inode->i_size + inode->i_blksize - 1) >> sb->s_blocksize_bits;
}

/**
 * v9fs_qid2ino - convert qid into inode number
 * @qid: qid to hash
 *
 * BUG: potential for inode number collisions?
 */

ino_t v9fs_qid2ino(struct v9fs_qid *qid)
{
	u64 path = qid->path + 2;
	ino_t i = 0;

	if (sizeof(ino_t) == sizeof(path))
		memcpy(&i, &path, sizeof(ino_t));
	else
		i = (ino_t) (path ^ (path >> 32));

	return i;
}

/**
 * v9fs_vfs_symlink - helper function to create symlinks
 * @dir: directory inode containing symlink
 * @dentry: dentry for symlink
 * @symname: symlink data
 *
 * See 9P2000.u RFC for more information
 *
 */

static int
v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
	int retval = -EPERM;
	struct v9fs_fid *newfid;
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
	struct v9fs_fcall *fcall = NULL;
	struct v9fs_stat *mistat = kmalloc(v9ses->maxdata, GFP_KERNEL);

	dprintk(DEBUG_VFS, " %lu,%s,%s\n", dir->i_ino, dentry->d_name.name,
		symname);

	if (!mistat)
		return -ENOMEM;

	if (!v9ses->extended) {
		dprintk(DEBUG_ERROR, "not extended\n");
		goto FreeFcall;
	}

	/* issue a create */
	retval = v9fs_create(dir, dentry, S_IFLNK, 0);
	if (retval != 0)
		goto FreeFcall;

	newfid = v9fs_fid_lookup(dentry, FID_OP);

	/* issue a twstat */
	v9fs_blank_mistat(v9ses, mistat);
	strcpy(mistat->data + 1, symname);
	mistat->extension = mistat->data + 1;
	retval = v9fs_t_wstat(v9ses, newfid->fid, mistat, &fcall);
	if (retval < 0) {
		dprintk(DEBUG_ERROR, "v9fs_t_wstat error: %s\n",
			FCALL_ERROR(fcall));
		goto FreeFcall;
	}

	kfree(fcall);

	if (v9fs_t_clunk(v9ses, newfid->fid, &fcall)) {
		dprintk(DEBUG_ERROR, "clunk for symlink failed: %s\n",
			FCALL_ERROR(fcall));
		goto FreeFcall;
	}

	d_drop(dentry);		/* FID - will this also clunk? */

      FreeFcall:
	kfree(mistat);
	kfree(fcall);

	return retval;
}

/**
 * v9fs_readlink - read a symlink's location (internal version)
 * @dentry: dentry for symlink
 * @buffer: buffer to load symlink location into
 * @buflen: length of buffer
 *
 */

static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen)
{
	int retval = -EPERM;

	struct v9fs_fcall *fcall = NULL;
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dentry->d_inode);
	struct v9fs_fid *fid = v9fs_fid_lookup(dentry, FID_OP);

	if (!fid) {
		dprintk(DEBUG_ERROR, "could not resolve fid from dentry\n");
		retval = -EBADF;
		goto FreeFcall;
	}

	if (!v9ses->extended) {
		retval = -EBADF;
		dprintk(DEBUG_ERROR, "not extended\n");
		goto FreeFcall;
	}

	dprintk(DEBUG_VFS, " %s\n", dentry->d_name.name);
	retval = v9fs_t_stat(v9ses, fid->fid, &fcall);

	if (retval < 0) {
		dprintk(DEBUG_ERROR, "stat error\n");
		goto FreeFcall;
	}

	if (!fcall)
		return -EIO;

	if (!(fcall->params.rstat.stat->mode & V9FS_DMSYMLINK)) {
		retval = -EINVAL;
		goto FreeFcall;
	}

	/* copy extension buffer into buffer */
	if (strlen(fcall->params.rstat.stat->extension) < buflen)
		buflen = strlen(fcall->params.rstat.stat->extension);

	memcpy(buffer, fcall->params.rstat.stat->extension, buflen + 1);

	retval = buflen;

      FreeFcall:
	kfree(fcall);

	return retval;
}

/**
 * v9fs_vfs_readlink - read a symlink's location
 * @dentry: dentry for symlink
 * @buf: buffer to load symlink location into
 * @buflen: length of buffer
 *
 */

static int v9fs_vfs_readlink(struct dentry *dentry, char __user * buffer,
			     int buflen)
{
	int retval;
	int ret;
	char *link = __getname();

	if (strlen(link) < buflen)
		buflen = strlen(link);

	dprintk(DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);

	retval = v9fs_readlink(dentry, link, buflen);

	if (retval > 0) {
		if ((ret = copy_to_user(buffer, link, retval)) != 0) {
			dprintk(DEBUG_ERROR, "problem copying to user: %d\n",
				ret);
			retval = ret;
		}
	}

	putname(link);
	return retval;
}

/**
 * v9fs_vfs_follow_link - follow a symlink path
 * @dentry: dentry for symlink
 * @nd: nameidata
 *
 */

static void *v9fs_vfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	int len = 0;
	char *link = __getname();

	dprintk(DEBUG_VFS, "%s n", dentry->d_name.name);

	if (!link)
		link = ERR_PTR(-ENOMEM);
	else {
		len = v9fs_readlink(dentry, link, strlen(link));

		if (len < 0) {
			putname(link);
			link = ERR_PTR(len);
		} else
			link[len] = 0;
	}
	nd_set_link(nd, link);

	return NULL;
}

/**
 * v9fs_vfs_put_link - release a symlink path
 * @dentry: dentry for symlink
 * @nd: nameidata
 *
 */

static void v9fs_vfs_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
{
	char *s = nd_get_link(nd);

	dprintk(DEBUG_VFS, " %s %s\n", dentry->d_name.name, s);
	if (!IS_ERR(s))
		putname(s);
}

/**
 * v9fs_vfs_link - create a hardlink
 * @old_dentry: dentry for file to link to
 * @dir: inode destination for new link
 * @dentry: dentry for link
 *
 */

/* XXX - lots of code dup'd from symlink and creates,
 * figure out a better reuse strategy
 */

static int
v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
	      struct dentry *dentry)
{
	int retval = -EPERM;
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
	struct v9fs_fcall *fcall = NULL;
	struct v9fs_stat *mistat = kmalloc(v9ses->maxdata, GFP_KERNEL);
	struct v9fs_fid *oldfid = v9fs_fid_lookup(old_dentry, FID_OP);
	struct v9fs_fid *newfid = NULL;
	char *symname = __getname();

	dprintk(DEBUG_VFS, " %lu,%s,%s\n", dir->i_ino, dentry->d_name.name,
		old_dentry->d_name.name);

	if (!v9ses->extended) {
		dprintk(DEBUG_ERROR, "not extended\n");
		goto FreeMem;
	}

	/* get fid of old_dentry */
	sprintf(symname, "hardlink(%d)\n", oldfid->fid);

	/* issue a create */
	retval = v9fs_create(dir, dentry, V9FS_DMLINK, 0);
	if (retval != 0)
		goto FreeMem;

	newfid = v9fs_fid_lookup(dentry, FID_OP);
	if (!newfid) {
		dprintk(DEBUG_ERROR, "couldn't resolve fid from dentry\n");
		goto FreeMem;
	}

	/* issue a twstat */
	v9fs_blank_mistat(v9ses, mistat);
	strcpy(mistat->data + 1, symname);
	mistat->extension = mistat->data + 1;
	retval = v9fs_t_wstat(v9ses, newfid->fid, mistat, &fcall);
	if (retval < 0) {
		dprintk(DEBUG_ERROR, "v9fs_t_wstat error: %s\n",
			FCALL_ERROR(fcall));
		goto FreeMem;
	}

	kfree(fcall);

	if (v9fs_t_clunk(v9ses, newfid->fid, &fcall)) {
		dprintk(DEBUG_ERROR, "clunk for symlink failed: %s\n",
			FCALL_ERROR(fcall));
		goto FreeMem;
	}

	d_drop(dentry);		/* FID - will this also clunk? */

	kfree(fcall);
	fcall = NULL;

      FreeMem:
	kfree(mistat);
	kfree(fcall);
	putname(symname);
	return retval;
}

/**
 * v9fs_vfs_mknod - create a special file
 * @dir: inode destination for new link
 * @dentry: dentry for file
 * @mode: mode for creation
 * @dev_t: device associated with special file
 *
 */

static int
v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t rdev)
{
	int retval = -EPERM;
	struct v9fs_fid *newfid;
	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
	struct v9fs_fcall *fcall = NULL;
	struct v9fs_stat *mistat = kmalloc(v9ses->maxdata, GFP_KERNEL);
	char *symname = __getname();

	dprintk(DEBUG_VFS, " %lu,%s mode: %x MAJOR: %u MINOR: %u\n", dir->i_ino,
		dentry->d_name.name, mode, MAJOR(rdev), MINOR(rdev));

	if (!mistat)
		return -ENOMEM;

	if (!new_valid_dev(rdev)) {
		retval = -EINVAL;
		goto FreeMem;
	}

	if (!v9ses->extended) {
		dprintk(DEBUG_ERROR, "not extended\n");
		goto FreeMem;
	}

	/* issue a create */
	retval = v9fs_create(dir, dentry, mode, 0);

	if (retval != 0)
		goto FreeMem;

	newfid = v9fs_fid_lookup(dentry, FID_OP);
	if (!newfid) {
		dprintk(DEBUG_ERROR, "coudn't resove fid from dentry\n");
		retval = -EINVAL;
		goto FreeMem;
	}

	/* build extension */
	if (S_ISBLK(mode))
		sprintf(symname, "b %u %u", MAJOR(rdev), MINOR(rdev));
	else if (S_ISCHR(mode))
		sprintf(symname, "c %u %u", MAJOR(rdev), MINOR(rdev));
	else if (S_ISFIFO(mode))
		;	/* DO NOTHING */
	else {
		retval = -EINVAL;
		goto FreeMem;
	}

	if (!S_ISFIFO(mode)) {
		/* issue a twstat */
		v9fs_blank_mistat(v9ses, mistat);
		strcpy(mistat->data + 1, symname);
		mistat->extension = mistat->data + 1;
		retval = v9fs_t_wstat(v9ses, newfid->fid, mistat, &fcall);
		if (retval < 0) {
			dprintk(DEBUG_ERROR, "v9fs_t_wstat error: %s\n",
				FCALL_ERROR(fcall));
			goto FreeMem;
		}
	}

	/* need to update dcache so we show up */
	kfree(fcall);

	if (v9fs_t_clunk(v9ses, newfid->fid, &fcall)) {
		dprintk(DEBUG_ERROR, "clunk for symlink failed: %s\n",
			FCALL_ERROR(fcall));
		goto FreeMem;
	}

	d_drop(dentry);		/* FID - will this also clunk? */

      FreeMem:
	kfree(mistat);
	kfree(fcall);
	putname(symname);

	return retval;
}

static struct inode_operations v9fs_dir_inode_operations = {
	.create = v9fs_vfs_create,
	.lookup = v9fs_vfs_lookup,
	.symlink = v9fs_vfs_symlink,
	.link = v9fs_vfs_link,
	.unlink = v9fs_vfs_unlink,
	.mkdir = v9fs_vfs_mkdir,
	.rmdir = v9fs_vfs_rmdir,
	.mknod = v9fs_vfs_mknod,
	.rename = v9fs_vfs_rename,
	.readlink = v9fs_vfs_readlink,
	.getattr = v9fs_vfs_getattr,
	.setattr = v9fs_vfs_setattr,
};

static struct inode_operations v9fs_file_inode_operations = {
	.getattr = v9fs_vfs_getattr,
	.setattr = v9fs_vfs_setattr,
};

static struct inode_operations v9fs_symlink_inode_operations = {
	.readlink = v9fs_vfs_readlink,
	.follow_link = v9fs_vfs_follow_link,
	.put_link = v9fs_vfs_put_link,
	.getattr = v9fs_vfs_getattr,
	.setattr = v9fs_vfs_setattr,
};