net/9p/client.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * net/9p/clnt.c
  *
  * 9P Client
  *
  *  Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
  *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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/poll.h>
 #include <linux/idr.h>
 #include <linux/mutex.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>
 #include <net/9p/9p.h>
 #include <linux/parser.h>
 #include <net/9p/transport.h>
 #include <net/9p/client.h>

 static struct p9_fid *p9_fid_create(struct p9_client *clnt);
 static void p9_fid_destroy(struct p9_fid *fid);
 static struct p9_stat *p9_clone_stat(struct p9_stat *st, int dotu);

 /*
   * Client Option Parsing (code inspired by NFS code)
   *  - a little lazy - parse all client options
   */

 enum {
 	Opt_msize,
 	Opt_trans,
 	Opt_legacy,
 	Opt_err,
 };

 static const match_table_t tokens = {
 	{Opt_msize, "msize=%u"},
 	{Opt_legacy, "noextend"},
 	{Opt_trans, "trans=%s"},
 	{Opt_err, NULL},
 };

 /**
  * v9fs_parse_options - parse mount options into session structure
  * @options: options string passed from mount
  * @v9ses: existing v9fs session information
  *
  * Return 0 upon success, -ERRNO upon failure
  */

 static int parse_opts(char *opts, struct p9_client *clnt)
 {
 	char *options;
 	char *p;
 	substring_t args[MAX_OPT_ARGS];
 	int option;
 	int ret = 0;

 	clnt->dotu = 1;
 	clnt->msize = 8192;

 	if (!opts)
 		return 0;

 	options = kstrdup(opts, GFP_KERNEL);
 	if (!options) {
 		P9_DPRINTK(P9_DEBUG_ERROR,
 				"failed to allocate copy of option string\n");
 		return -ENOMEM;
 	}

 	while ((p = strsep(&options, ",")) != NULL) {
 		int token;
 		if (!*p)
 			continue;
 		token = match_token(p, tokens, args);
 		if (token < Opt_trans) {
 			int r = match_int(&args[0], &option);
 			if (r < 0) {
 				P9_DPRINTK(P9_DEBUG_ERROR,
 					"integer field, but no integer?\n");
 				ret = r;
 				continue;
 			}
 		}
 		switch (token) {
 		case Opt_msize:
 			clnt->msize = option;
 			break;
 		case Opt_trans:
 			clnt->trans_mod = v9fs_get_trans_by_name(&args[0]);
 			break;
 		case Opt_legacy:
 			clnt->dotu = 0;
 			break;
 		default:
 			continue;
 		}
 	}

 	if (!clnt->trans_mod)
 		clnt->trans_mod = v9fs_get_default_trans();

 	kfree(options);
 	return ret;
 }


 /**
  * p9_client_rpc - sends 9P request and waits until a response is available.
  *      The function can be interrupted.
  * @c: client data
  * @tc: request to be sent
  * @rc: pointer where a pointer to the response is stored
  */
 int
 p9_client_rpc(struct p9_client *c, struct p9_fcall *tc,
 	struct p9_fcall **rc)
 {
 	return c->trans->rpc(c->trans, tc, rc);
 }

 struct p9_client *p9_client_create(const char *dev_name, char *options)
 {
 	int err, n;
 	struct p9_client *clnt;
 	struct p9_fcall *tc, *rc;
 	struct p9_str *version;

 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = kmalloc(sizeof(struct p9_client), GFP_KERNEL);
 	if (!clnt)
 		return ERR_PTR(-ENOMEM);

 	clnt->trans_mod = NULL;
 	clnt->trans = NULL;
 	spin_lock_init(&clnt->lock);
 	INIT_LIST_HEAD(&clnt->fidlist);
 	clnt->fidpool = p9_idpool_create();
 	if (IS_ERR(clnt->fidpool)) {
 		err = PTR_ERR(clnt->fidpool);
 		clnt->fidpool = NULL;
 		goto error;
 	}

 	err = parse_opts(options, clnt);
 	if (err < 0)
 		goto error;

 	if (clnt->trans_mod == NULL) {
 		err = -EPROTONOSUPPORT;
 		P9_DPRINTK(P9_DEBUG_ERROR,
 				"No transport defined or default transport\n");
 		goto error;
 	}

 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p trans %p msize %d dotu %d\n",
 		clnt, clnt->trans_mod, clnt->msize, clnt->dotu);


 	clnt->trans = clnt->trans_mod->create(dev_name, options, clnt->msize,
 								clnt->dotu);
 	if (IS_ERR(clnt->trans)) {
 		err = PTR_ERR(clnt->trans);
 		clnt->trans = NULL;
 		goto error;
 	}

 	if ((clnt->msize+P9_IOHDRSZ) > clnt->trans_mod->maxsize)
 		clnt->msize = clnt->trans_mod->maxsize-P9_IOHDRSZ;

 	tc = p9_create_tversion(clnt->msize, clnt->dotu?"9P2000.u":"9P2000");
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto error;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto error;

 	version = &rc->params.rversion.version;
 	if (version->len == 8 && !memcmp(version->str, "9P2000.u", 8))
 		clnt->dotu = 1;
 	else if (version->len == 6 && !memcmp(version->str, "9P2000", 6))
 		clnt->dotu = 0;
 	else {
 		err = -EREMOTEIO;
 		goto error;
 	}

 	n = rc->params.rversion.msize;
 	if (n < clnt->msize)
 		clnt->msize = n;

 	kfree(tc);
 	kfree(rc);
 	return clnt;

 error:
 	kfree(tc);
 	kfree(rc);
 	p9_client_destroy(clnt);
 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(p9_client_create);

 void p9_client_destroy(struct p9_client *clnt)
 {
 	struct p9_fid *fid, *fidptr;

 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);

 	if (clnt->trans) {
 		clnt->trans->close(clnt->trans);
 		kfree(clnt->trans);
 		clnt->trans = NULL;
 	}

 	v9fs_put_trans(clnt->trans_mod);

 	list_for_each_entry_safe(fid, fidptr, &clnt->fidlist, flist)
 		p9_fid_destroy(fid);

 	if (clnt->fidpool)
 		p9_idpool_destroy(clnt->fidpool);

 	kfree(clnt);
 }
 EXPORT_SYMBOL(p9_client_destroy);

 void p9_client_disconnect(struct p9_client *clnt)
 {
 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
 	clnt->trans->status = Disconnected;
 }
 EXPORT_SYMBOL(p9_client_disconnect);

 struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
 	char *uname, u32 n_uname, char *aname)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_fid *fid;

 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p afid %d uname %s aname %s\n",
 		clnt, afid?afid->fid:-1, uname, aname);
 	err = 0;
 	tc = NULL;
 	rc = NULL;

 	fid = p9_fid_create(clnt);
 	if (IS_ERR(fid)) {
 		err = PTR_ERR(fid);
 		fid = NULL;
 		goto error;
 	}

 	tc = p9_create_tattach(fid->fid, afid?afid->fid:P9_NOFID, uname, aname,
 		n_uname, clnt->dotu);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto error;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto error;

 	memmove(&fid->qid, &rc->params.rattach.qid, sizeof(struct p9_qid));
 	kfree(tc);
 	kfree(rc);
 	return fid;

 error:
 	kfree(tc);
 	kfree(rc);
 	if (fid)
 		p9_fid_destroy(fid);
 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(p9_client_attach);

 struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname,
 	u32 n_uname, char *aname)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_fid *fid;

 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p uname %s aname %s\n", clnt, uname,
 									aname);
 	err = 0;
 	tc = NULL;
 	rc = NULL;

 	fid = p9_fid_create(clnt);
 	if (IS_ERR(fid)) {
 		err = PTR_ERR(fid);
 		fid = NULL;
 		goto error;
 	}

 	tc = p9_create_tauth(fid->fid, uname, aname, n_uname, clnt->dotu);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto error;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto error;

 	memmove(&fid->qid, &rc->params.rauth.qid, sizeof(struct p9_qid));
 	kfree(tc);
 	kfree(rc);
 	return fid;

 error:
 	kfree(tc);
 	kfree(rc);
 	if (fid)
 		p9_fid_destroy(fid);
 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(p9_client_auth);

 struct p9_fid *p9_client_walk(struct p9_fid *oldfid, int nwname, char **wnames,
 	int clone)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;
 	struct p9_fid *fid;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d nwname %d wname[0] %s\n",
 		oldfid->fid, nwname, wnames?wnames[0]:NULL);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = oldfid->clnt;
 	if (clone) {
 		fid = p9_fid_create(clnt);
 		if (IS_ERR(fid)) {
 			err = PTR_ERR(fid);
 			fid = NULL;
 			goto error;
 		}

 		fid->uid = oldfid->uid;
 	} else
 		fid = oldfid;

 	tc = p9_create_twalk(oldfid->fid, fid->fid, nwname, wnames);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto error;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err) {
 		if (rc && rc->id == P9_RWALK)
 			goto clunk_fid;
 		else
 			goto error;
 	}

 	if (rc->params.rwalk.nwqid != nwname) {
 		err = -ENOENT;
 		goto clunk_fid;
 	}

 	if (nwname)
 		memmove(&fid->qid,
 			&rc->params.rwalk.wqids[rc->params.rwalk.nwqid - 1],
 			sizeof(struct p9_qid));
 	else
 		fid->qid = oldfid->qid;

 	kfree(tc);
 	kfree(rc);
 	return fid;

 clunk_fid:
 	kfree(tc);
 	kfree(rc);
 	rc = NULL;
 	tc = p9_create_tclunk(fid->fid);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto error;
 	}

 	p9_client_rpc(clnt, tc, &rc);

 error:
 	kfree(tc);
 	kfree(rc);
 	if (fid && (fid != oldfid))
 		p9_fid_destroy(fid);

 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(p9_client_walk);

 int p9_client_open(struct p9_fid *fid, int mode)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d mode %d\n", fid->fid, mode);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;

 	if (fid->mode != -1)
 		return -EINVAL;

 	tc = p9_create_topen(fid->fid, mode);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto done;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto done;

 	fid->mode = mode;
 	fid->iounit = rc->params.ropen.iounit;

 done:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_open);

 int p9_client_fcreate(struct p9_fid *fid, char *name, u32 perm, int mode,
 		     char *extension)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d name %s perm %d mode %d\n", fid->fid,
 		name, perm, mode);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;

 	if (fid->mode != -1)
 		return -EINVAL;

 	tc = p9_create_tcreate(fid->fid, name, perm, mode, extension,
 							       clnt->dotu);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto done;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto done;

 	fid->mode = mode;
 	fid->iounit = rc->params.ropen.iounit;

 done:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_fcreate);

 int p9_client_clunk(struct p9_fid *fid)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;

 	tc = p9_create_tclunk(fid->fid);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto done;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto done;

 	p9_fid_destroy(fid);

 done:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_clunk);

 int p9_client_remove(struct p9_fid *fid)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;

 	tc = p9_create_tremove(fid->fid);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto done;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto done;

 	p9_fid_destroy(fid);

 done:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_remove);

 int p9_client_read(struct p9_fid *fid, char *data, u64 offset, u32 count)
 {
 	int err, n, rsize, total;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu %d\n", fid->fid,
 					(long long unsigned) offset, count);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;
 	total = 0;

 	rsize = fid->iounit;
 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
 		rsize = clnt->msize - P9_IOHDRSZ;

 	do {
 		if (count < rsize)
 			rsize = count;

 		tc = p9_create_tread(fid->fid, offset, rsize);
 		if (IS_ERR(tc)) {
 			err = PTR_ERR(tc);
 			tc = NULL;
 			goto error;
 		}

 		err = p9_client_rpc(clnt, tc, &rc);
 		if (err)
 			goto error;

 		n = rc->params.rread.count;
 		if (n > count)
 			n = count;

 		memmove(data, rc->params.rread.data, n);
 		count -= n;
 		data += n;
 		offset += n;
 		total += n;
 		kfree(tc);
 		tc = NULL;
 		kfree(rc);
 		rc = NULL;
 	} while (count > 0 && n == rsize);

 	return total;

 error:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_read);

 int p9_client_write(struct p9_fid *fid, char *data, u64 offset, u32 count)
 {
 	int err, n, rsize, total;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
 					(long long unsigned) offset, count);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;
 	total = 0;

 	rsize = fid->iounit;
 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
 		rsize = clnt->msize - P9_IOHDRSZ;

 	do {
 		if (count < rsize)
 			rsize = count;

 		tc = p9_create_twrite(fid->fid, offset, rsize, data);
 		if (IS_ERR(tc)) {
 			err = PTR_ERR(tc);
 			tc = NULL;
 			goto error;
 		}

 		err = p9_client_rpc(clnt, tc, &rc);
 		if (err)
 			goto error;

 		n = rc->params.rread.count;
 		count -= n;
 		data += n;
 		offset += n;
 		total += n;
 		kfree(tc);
 		tc = NULL;
 		kfree(rc);
 		rc = NULL;
 	} while (count > 0);

 	return total;

 error:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_write);

 int
 p9_client_uread(struct p9_fid *fid, char __user *data, u64 offset, u32 count)
 {
 	int err, n, rsize, total;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
 					(long long unsigned) offset, count);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;
 	total = 0;

 	rsize = fid->iounit;
 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
 		rsize = clnt->msize - P9_IOHDRSZ;

 	do {
 		if (count < rsize)
 			rsize = count;

 		tc = p9_create_tread(fid->fid, offset, rsize);
 		if (IS_ERR(tc)) {
 			err = PTR_ERR(tc);
 			tc = NULL;
 			goto error;
 		}

 		err = p9_client_rpc(clnt, tc, &rc);
 		if (err)
 			goto error;

 		n = rc->params.rread.count;
 		if (n > count)
 			n = count;

 		err = copy_to_user(data, rc->params.rread.data, n);
 		if (err) {
 			err = -EFAULT;
 			goto error;
 		}

 		count -= n;
 		data += n;
 		offset += n;
 		total += n;
 		kfree(tc);
 		tc = NULL;
 		kfree(rc);
 		rc = NULL;
 	} while (count > 0 && n == rsize);

 	return total;

 error:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_uread);

 int
 p9_client_uwrite(struct p9_fid *fid, const char __user *data, u64 offset,
 								   u32 count)
 {
 	int err, n, rsize, total;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
 					(long long unsigned) offset, count);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;
 	total = 0;

 	rsize = fid->iounit;
 	if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
 		rsize = clnt->msize - P9_IOHDRSZ;

 	do {
 		if (count < rsize)
 			rsize = count;

 		tc = p9_create_twrite_u(fid->fid, offset, rsize, data);
 		if (IS_ERR(tc)) {
 			err = PTR_ERR(tc);
 			tc = NULL;
 			goto error;
 		}

 		err = p9_client_rpc(clnt, tc, &rc);
 		if (err)
 			goto error;

 		n = rc->params.rread.count;
 		count -= n;
 		data += n;
 		offset += n;
 		total += n;
 		kfree(tc);
 		tc = NULL;
 		kfree(rc);
 		rc = NULL;
 	} while (count > 0);

 	return total;

 error:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_uwrite);

 int p9_client_readn(struct p9_fid *fid, char *data, u64 offset, u32 count)
 {
 	int n, total;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
 					(long long unsigned) offset, count);
 	n = 0;
 	total = 0;
 	while (count) {
 		n = p9_client_read(fid, data, offset, count);
 		if (n <= 0)
 			break;

 		data += n;
 		offset += n;
 		count -= n;
 		total += n;
 	}

 	if (n < 0)
 		total = n;

 	return total;
 }
 EXPORT_SYMBOL(p9_client_readn);

 struct p9_stat *p9_client_stat(struct p9_fid *fid)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;
 	struct p9_stat *ret;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	ret = NULL;
 	clnt = fid->clnt;

 	tc = p9_create_tstat(fid->fid);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto error;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);
 	if (err)
 		goto error;

 	ret = p9_clone_stat(&rc->params.rstat.stat, clnt->dotu);
 	if (IS_ERR(ret)) {
 		err = PTR_ERR(ret);
 		ret = NULL;
 		goto error;
 	}

 	kfree(tc);
 	kfree(rc);
 	return ret;

 error:
 	kfree(tc);
 	kfree(rc);
 	kfree(ret);
 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(p9_client_stat);

 int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst)
 {
 	int err;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	clnt = fid->clnt;

 	tc = p9_create_twstat(fid->fid, wst, clnt->dotu);
 	if (IS_ERR(tc)) {
 		err = PTR_ERR(tc);
 		tc = NULL;
 		goto done;
 	}

 	err = p9_client_rpc(clnt, tc, &rc);

 done:
 	kfree(tc);
 	kfree(rc);
 	return err;
 }
 EXPORT_SYMBOL(p9_client_wstat);

 struct p9_stat *p9_client_dirread(struct p9_fid *fid, u64 offset)
 {
 	int err, n, m;
 	struct p9_fcall *tc, *rc;
 	struct p9_client *clnt;
 	struct p9_stat st, *ret;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu\n", fid->fid,
 						(long long unsigned) offset);
 	err = 0;
 	tc = NULL;
 	rc = NULL;
 	ret = NULL;
 	clnt = fid->clnt;

 	/* if the offset is below or above the current response, free it */
 	if (offset < fid->rdir_fpos || (fid->rdir_fcall &&
 		offset >= fid->rdir_fpos+fid->rdir_fcall->params.rread.count)) {
 		fid->rdir_pos = 0;
 		if (fid->rdir_fcall)
 			fid->rdir_fpos += fid->rdir_fcall->params.rread.count;

 		kfree(fid->rdir_fcall);
 		fid->rdir_fcall = NULL;
 		if (offset < fid->rdir_fpos)
 			fid->rdir_fpos = 0;
 	}

 	if (!fid->rdir_fcall) {
 		n = fid->iounit;
 		if (!n || n > clnt->msize-P9_IOHDRSZ)
 			n = clnt->msize - P9_IOHDRSZ;

 		while (1) {
 			if (fid->rdir_fcall) {
 				fid->rdir_fpos +=
 					fid->rdir_fcall->params.rread.count;
 				kfree(fid->rdir_fcall);
 				fid->rdir_fcall = NULL;
 			}

 			tc = p9_create_tread(fid->fid, fid->rdir_fpos, n);
 			if (IS_ERR(tc)) {
 				err = PTR_ERR(tc);
 				tc = NULL;
 				goto error;
 			}

 			err = p9_client_rpc(clnt, tc, &rc);
 			if (err)
 				goto error;

 			n = rc->params.rread.count;
 			if (n == 0)
 				goto done;

 			fid->rdir_fcall = rc;
 			rc = NULL;
 			if (offset >= fid->rdir_fpos &&
 						offset < fid->rdir_fpos+n)
 				break;
 		}

 		fid->rdir_pos = 0;
 	}

 	m = offset - fid->rdir_fpos;
 	if (m < 0)
 		goto done;

 	n = p9_deserialize_stat(fid->rdir_fcall->params.rread.data + m,
 		fid->rdir_fcall->params.rread.count - m, &st, clnt->dotu);

 	if (!n) {
 		err = -EIO;
 		goto error;
 	}

 	fid->rdir_pos += n;
 	st.size = n;
 	ret = p9_clone_stat(&st, clnt->dotu);
 	if (IS_ERR(ret)) {
 		err = PTR_ERR(ret);
 		ret = NULL;
 		goto error;
 	}

 done:
 	kfree(tc);
 	kfree(rc);
 	return ret;

 error:
 	kfree(tc);
 	kfree(rc);
 	kfree(ret);
 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(p9_client_dirread);

 static struct p9_stat *p9_clone_stat(struct p9_stat *st, int dotu)
 {
 	int n;
 	char *p;
 	struct p9_stat *ret;

 	n = sizeof(struct p9_stat) + st->name.len + st->uid.len + st->gid.len +
 		st->muid.len;

 	if (dotu)
 		n += st->extension.len;

 	ret = kmalloc(n, GFP_KERNEL);
 	if (!ret)
 		return ERR_PTR(-ENOMEM);

 	memmove(ret, st, sizeof(struct p9_stat));
 	p = ((char *) ret) + sizeof(struct p9_stat);
 	memmove(p, st->name.str, st->name.len);
 	ret->name.str = p;
 	p += st->name.len;
 	memmove(p, st->uid.str, st->uid.len);
 	ret->uid.str = p;
 	p += st->uid.len;
 	memmove(p, st->gid.str, st->gid.len);
 	ret->gid.str = p;
 	p += st->gid.len;
 	memmove(p, st->muid.str, st->muid.len);
 	ret->muid.str = p;
 	p += st->muid.len;

 	if (dotu) {
 		memmove(p, st->extension.str, st->extension.len);
 		ret->extension.str = p;
 		p += st->extension.len;
 	}

 	return ret;
 }

 static struct p9_fid *p9_fid_create(struct p9_client *clnt)
 {
 	int err;
 	struct p9_fid *fid;

 	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
 	fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
 	if (!fid)
 		return ERR_PTR(-ENOMEM);

 	fid->fid = p9_idpool_get(clnt->fidpool);
 	if (fid->fid < 0) {
 		err = -ENOSPC;
 		goto error;
 	}

 	memset(&fid->qid, 0, sizeof(struct p9_qid));
 	fid->mode = -1;
 	fid->rdir_fpos = 0;
 	fid->rdir_pos = 0;
 	fid->rdir_fcall = NULL;
 	fid->uid = current->fsuid;
 	fid->clnt = clnt;
 	fid->aux = NULL;

 	spin_lock(&clnt->lock);
 	list_add(&fid->flist, &clnt->fidlist);
 	spin_unlock(&clnt->lock);

 	return fid;

 error:
 	kfree(fid);
 	return ERR_PTR(err);
 }

 static void p9_fid_destroy(struct p9_fid *fid)
 {
 	struct p9_client *clnt;

 	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
 	clnt = fid->clnt;
 	p9_idpool_put(fid->fid, clnt->fidpool);
 	spin_lock(&clnt->lock);
 	list_del(&fid->flist);
 	spin_unlock(&clnt->lock);
 	kfree(fid->rdir_fcall);
 	kfree(fid);
 }
	/*
	* net/9p/clnt.c
	*
	* 9P Client
	*
	* Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
	* Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2
	* as published by the Free Software Foundation.
	*
	* 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/poll.h>
	#include <linux/idr.h>
	#include <linux/mutex.h>
	#include <linux/sched.h>
	#include <linux/uaccess.h>
	#include <net/9p/9p.h>
	#include <linux/parser.h>
	#include <net/9p/transport.h>
	#include <net/9p/client.h>

	static struct p9_fid p9_fid_create(struct p9_client clnt);
	static void p9_fid_destroy(struct p9_fid *fid);
	static struct p9_stat p9_clone_stat(struct p9_stat st, int dotu);

	/*
	* Client Option Parsing (code inspired by NFS code)
	* - a little lazy - parse all client options
	*/

	enum {
	Opt_msize,
	Opt_trans,
	Opt_legacy,
	Opt_err,
	};

	static const match_table_t tokens = {
	{Opt_msize, "msize=%u"},
	{Opt_legacy, "noextend"},
	{Opt_trans, "trans=%s"},
	{Opt_err, NULL},
	};

	/**
	* v9fs_parse_options - parse mount options into session structure
	* @options: options string passed from mount
	* @v9ses: existing v9fs session information
	*
	* Return 0 upon success, -ERRNO upon failure
	*/

	static int parse_opts(char opts, struct p9_client clnt)
	{
	char *options;
	char *p;
	substring_t args[MAX_OPT_ARGS];
	int option;
	int ret = 0;

	clnt->dotu = 1;
	clnt->msize = 8192;

	if (!opts)
	return 0;

	options = kstrdup(opts, GFP_KERNEL);
	if (!options) {
	P9_DPRINTK(P9_DEBUG_ERROR,
	"failed to allocate copy of option string\n");
	return -ENOMEM;
	}

	while ((p = strsep(&options, ",")) != NULL) {
	int token;
	if (!*p)
	continue;
	token = match_token(p, tokens, args);
	if (token < Opt_trans) {
	int r = match_int(&args[0], &option);
	if (r < 0) {
	P9_DPRINTK(P9_DEBUG_ERROR,
	"integer field, but no integer?\n");
	ret = r;
	continue;
	}
	}
	switch (token) {
	case Opt_msize:
	clnt->msize = option;
	break;
	case Opt_trans:
	clnt->trans_mod = v9fs_get_trans_by_name(&args[0]);
	break;
	case Opt_legacy:
	clnt->dotu = 0;
	break;
	default:
	continue;
	}
	}

	if (!clnt->trans_mod)
	clnt->trans_mod = v9fs_get_default_trans();

	kfree(options);
	return ret;
	}


	/**
	* p9_client_rpc - sends 9P request and waits until a response is available.
	* The function can be interrupted.
	* @c: client data
	* @tc: request to be sent
	* @rc: pointer where a pointer to the response is stored
	*/
	int
	p9_client_rpc(struct p9_client c, struct p9_fcall tc,
	struct p9_fcall **rc)
	{
	return c->trans->rpc(c->trans, tc, rc);
	}

	struct p9_client p9_client_create(const char dev_name, char *options)
	{
	int err, n;
	struct p9_client *clnt;
	struct p9_fcall tc, rc;
	struct p9_str *version;

	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = kmalloc(sizeof(struct p9_client), GFP_KERNEL);
	if (!clnt)
	return ERR_PTR(-ENOMEM);

	clnt->trans_mod = NULL;
	clnt->trans = NULL;
	spin_lock_init(&clnt->lock);
	INIT_LIST_HEAD(&clnt->fidlist);
	clnt->fidpool = p9_idpool_create();
	if (IS_ERR(clnt->fidpool)) {
	err = PTR_ERR(clnt->fidpool);
	clnt->fidpool = NULL;
	goto error;
	}

	err = parse_opts(options, clnt);
	if (err < 0)
	goto error;

	if (clnt->trans_mod == NULL) {
	err = -EPROTONOSUPPORT;
	P9_DPRINTK(P9_DEBUG_ERROR,
	"No transport defined or default transport\n");
	goto error;
	}

	P9_DPRINTK(P9_DEBUG_9P, "clnt %p trans %p msize %d dotu %d\n",
	clnt, clnt->trans_mod, clnt->msize, clnt->dotu);


	clnt->trans = clnt->trans_mod->create(dev_name, options, clnt->msize,
	clnt->dotu);
	if (IS_ERR(clnt->trans)) {
	err = PTR_ERR(clnt->trans);
	clnt->trans = NULL;
	goto error;
	}

	if ((clnt->msize+P9_IOHDRSZ) > clnt->trans_mod->maxsize)
	clnt->msize = clnt->trans_mod->maxsize-P9_IOHDRSZ;

	tc = p9_create_tversion(clnt->msize, clnt->dotu?"9P2000.u":"9P2000");
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	version = &rc->params.rversion.version;
	if (version->len == 8 && !memcmp(version->str, "9P2000.u", 8))
	clnt->dotu = 1;
	else if (version->len == 6 && !memcmp(version->str, "9P2000", 6))
	clnt->dotu = 0;
	else {
	err = -EREMOTEIO;
	goto error;
	}

	n = rc->params.rversion.msize;
	if (n < clnt->msize)
	clnt->msize = n;

	kfree(tc);
	kfree(rc);
	return clnt;

	error:
	kfree(tc);
	kfree(rc);
	p9_client_destroy(clnt);
	return ERR_PTR(err);
	}
	EXPORT_SYMBOL(p9_client_create);

	void p9_client_destroy(struct p9_client *clnt)
	{
	struct p9_fid fid, fidptr;

	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);

	if (clnt->trans) {
	clnt->trans->close(clnt->trans);
	kfree(clnt->trans);
	clnt->trans = NULL;
	}

	v9fs_put_trans(clnt->trans_mod);

	list_for_each_entry_safe(fid, fidptr, &clnt->fidlist, flist)
	p9_fid_destroy(fid);

	if (clnt->fidpool)
	p9_idpool_destroy(clnt->fidpool);

	kfree(clnt);
	}
	EXPORT_SYMBOL(p9_client_destroy);

	void p9_client_disconnect(struct p9_client *clnt)
	{
	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
	clnt->trans->status = Disconnected;
	}
	EXPORT_SYMBOL(p9_client_disconnect);

	struct p9_fid p9_client_attach(struct p9_client clnt, struct p9_fid *afid,
	char uname, u32 n_uname, char aname)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_fid *fid;

	P9_DPRINTK(P9_DEBUG_9P, "clnt %p afid %d uname %s aname %s\n",
	clnt, afid?afid->fid:-1, uname, aname);
	err = 0;
	tc = NULL;
	rc = NULL;

	fid = p9_fid_create(clnt);
	if (IS_ERR(fid)) {
	err = PTR_ERR(fid);
	fid = NULL;
	goto error;
	}

	tc = p9_create_tattach(fid->fid, afid?afid->fid:P9_NOFID, uname, aname,
	n_uname, clnt->dotu);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	memmove(&fid->qid, &rc->params.rattach.qid, sizeof(struct p9_qid));
	kfree(tc);
	kfree(rc);
	return fid;

	error:
	kfree(tc);
	kfree(rc);
	if (fid)
	p9_fid_destroy(fid);
	return ERR_PTR(err);
	}
	EXPORT_SYMBOL(p9_client_attach);

	struct p9_fid p9_client_auth(struct p9_client clnt, char *uname,
	u32 n_uname, char *aname)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_fid *fid;

	P9_DPRINTK(P9_DEBUG_9P, "clnt %p uname %s aname %s\n", clnt, uname,
	aname);
	err = 0;
	tc = NULL;
	rc = NULL;

	fid = p9_fid_create(clnt);
	if (IS_ERR(fid)) {
	err = PTR_ERR(fid);
	fid = NULL;
	goto error;
	}

	tc = p9_create_tauth(fid->fid, uname, aname, n_uname, clnt->dotu);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	memmove(&fid->qid, &rc->params.rauth.qid, sizeof(struct p9_qid));
	kfree(tc);
	kfree(rc);
	return fid;

	error:
	kfree(tc);
	kfree(rc);
	if (fid)
	p9_fid_destroy(fid);
	return ERR_PTR(err);
	}
	EXPORT_SYMBOL(p9_client_auth);

	struct p9_fid p9_client_walk(struct p9_fid oldfid, int nwname, char **wnames,
	int clone)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;
	struct p9_fid *fid;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d nwname %d wname[0] %s\n",
	oldfid->fid, nwname, wnames?wnames[0]:NULL);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = oldfid->clnt;
	if (clone) {
	fid = p9_fid_create(clnt);
	if (IS_ERR(fid)) {
	err = PTR_ERR(fid);
	fid = NULL;
	goto error;
	}

	fid->uid = oldfid->uid;
	} else
	fid = oldfid;

	tc = p9_create_twalk(oldfid->fid, fid->fid, nwname, wnames);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err) {
	if (rc && rc->id == P9_RWALK)
	goto clunk_fid;
	else
	goto error;
	}

	if (rc->params.rwalk.nwqid != nwname) {
	err = -ENOENT;
	goto clunk_fid;
	}

	if (nwname)
	memmove(&fid->qid,
	&rc->params.rwalk.wqids[rc->params.rwalk.nwqid - 1],
	sizeof(struct p9_qid));
	else
	fid->qid = oldfid->qid;

	kfree(tc);
	kfree(rc);
	return fid;

	clunk_fid:
	kfree(tc);
	kfree(rc);
	rc = NULL;
	tc = p9_create_tclunk(fid->fid);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	p9_client_rpc(clnt, tc, &rc);

	error:
	kfree(tc);
	kfree(rc);
	if (fid && (fid != oldfid))
	p9_fid_destroy(fid);

	return ERR_PTR(err);
	}
	EXPORT_SYMBOL(p9_client_walk);

	int p9_client_open(struct p9_fid *fid, int mode)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d mode %d\n", fid->fid, mode);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;

	if (fid->mode != -1)
	return -EINVAL;

	tc = p9_create_topen(fid->fid, mode);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto done;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto done;

	fid->mode = mode;
	fid->iounit = rc->params.ropen.iounit;

	done:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_open);

	int p9_client_fcreate(struct p9_fid fid, char name, u32 perm, int mode,
	char *extension)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d name %s perm %d mode %d\n", fid->fid,
	name, perm, mode);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;

	if (fid->mode != -1)
	return -EINVAL;

	tc = p9_create_tcreate(fid->fid, name, perm, mode, extension,
	clnt->dotu);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto done;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto done;

	fid->mode = mode;
	fid->iounit = rc->params.ropen.iounit;

	done:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_fcreate);

	int p9_client_clunk(struct p9_fid *fid)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;

	tc = p9_create_tclunk(fid->fid);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto done;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto done;

	p9_fid_destroy(fid);

	done:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_clunk);

	int p9_client_remove(struct p9_fid *fid)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;

	tc = p9_create_tremove(fid->fid);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto done;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto done;

	p9_fid_destroy(fid);

	done:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_remove);

	int p9_client_read(struct p9_fid fid, char data, u64 offset, u32 count)
	{
	int err, n, rsize, total;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu %d\n", fid->fid,
	(long long unsigned) offset, count);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;
	total = 0;

	rsize = fid->iounit;
	if (!rsize \|\| rsize > clnt->msize-P9_IOHDRSZ)
	rsize = clnt->msize - P9_IOHDRSZ;

	do {
	if (count < rsize)
	rsize = count;

	tc = p9_create_tread(fid->fid, offset, rsize);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	n = rc->params.rread.count;
	if (n > count)
	n = count;

	memmove(data, rc->params.rread.data, n);
	count -= n;
	data += n;
	offset += n;
	total += n;
	kfree(tc);
	tc = NULL;
	kfree(rc);
	rc = NULL;
	} while (count > 0 && n == rsize);

	return total;

	error:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_read);

	int p9_client_write(struct p9_fid fid, char data, u64 offset, u32 count)
	{
	int err, n, rsize, total;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
	(long long unsigned) offset, count);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;
	total = 0;

	rsize = fid->iounit;
	if (!rsize \|\| rsize > clnt->msize-P9_IOHDRSZ)
	rsize = clnt->msize - P9_IOHDRSZ;

	do {
	if (count < rsize)
	rsize = count;

	tc = p9_create_twrite(fid->fid, offset, rsize, data);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	n = rc->params.rread.count;
	count -= n;
	data += n;
	offset += n;
	total += n;
	kfree(tc);
	tc = NULL;
	kfree(rc);
	rc = NULL;
	} while (count > 0);

	return total;

	error:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_write);

	int
	p9_client_uread(struct p9_fid fid, char __user data, u64 offset, u32 count)
	{
	int err, n, rsize, total;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
	(long long unsigned) offset, count);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;
	total = 0;

	rsize = fid->iounit;
	if (!rsize \|\| rsize > clnt->msize-P9_IOHDRSZ)
	rsize = clnt->msize - P9_IOHDRSZ;

	do {
	if (count < rsize)
	rsize = count;

	tc = p9_create_tread(fid->fid, offset, rsize);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	n = rc->params.rread.count;
	if (n > count)
	n = count;

	err = copy_to_user(data, rc->params.rread.data, n);
	if (err) {
	err = -EFAULT;
	goto error;
	}

	count -= n;
	data += n;
	offset += n;
	total += n;
	kfree(tc);
	tc = NULL;
	kfree(rc);
	rc = NULL;
	} while (count > 0 && n == rsize);

	return total;

	error:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_uread);

	int
	p9_client_uwrite(struct p9_fid fid, const char __user data, u64 offset,
	u32 count)
	{
	int err, n, rsize, total;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
	(long long unsigned) offset, count);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;
	total = 0;

	rsize = fid->iounit;
	if (!rsize \|\| rsize > clnt->msize-P9_IOHDRSZ)
	rsize = clnt->msize - P9_IOHDRSZ;

	do {
	if (count < rsize)
	rsize = count;

	tc = p9_create_twrite_u(fid->fid, offset, rsize, data);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	n = rc->params.rread.count;
	count -= n;
	data += n;
	offset += n;
	total += n;
	kfree(tc);
	tc = NULL;
	kfree(rc);
	rc = NULL;
	} while (count > 0);

	return total;

	error:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_uwrite);

	int p9_client_readn(struct p9_fid fid, char data, u64 offset, u32 count)
	{
	int n, total;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu count %d\n", fid->fid,
	(long long unsigned) offset, count);
	n = 0;
	total = 0;
	while (count) {
	n = p9_client_read(fid, data, offset, count);
	if (n <= 0)
	break;

	data += n;
	offset += n;
	count -= n;
	total += n;
	}

	if (n < 0)
	total = n;

	return total;
	}
	EXPORT_SYMBOL(p9_client_readn);

	struct p9_stat p9_client_stat(struct p9_fid fid)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;
	struct p9_stat *ret;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
	err = 0;
	tc = NULL;
	rc = NULL;
	ret = NULL;
	clnt = fid->clnt;

	tc = p9_create_tstat(fid->fid);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	ret = p9_clone_stat(&rc->params.rstat.stat, clnt->dotu);
	if (IS_ERR(ret)) {
	err = PTR_ERR(ret);
	ret = NULL;
	goto error;
	}

	kfree(tc);
	kfree(rc);
	return ret;

	error:
	kfree(tc);
	kfree(rc);
	kfree(ret);
	return ERR_PTR(err);
	}
	EXPORT_SYMBOL(p9_client_stat);

	int p9_client_wstat(struct p9_fid fid, struct p9_wstat wst)
	{
	int err;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
	err = 0;
	tc = NULL;
	rc = NULL;
	clnt = fid->clnt;

	tc = p9_create_twstat(fid->fid, wst, clnt->dotu);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto done;
	}

	err = p9_client_rpc(clnt, tc, &rc);

	done:
	kfree(tc);
	kfree(rc);
	return err;
	}
	EXPORT_SYMBOL(p9_client_wstat);

	struct p9_stat p9_client_dirread(struct p9_fid fid, u64 offset)
	{
	int err, n, m;
	struct p9_fcall tc, rc;
	struct p9_client *clnt;
	struct p9_stat st, *ret;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d offset %llu\n", fid->fid,
	(long long unsigned) offset);
	err = 0;
	tc = NULL;
	rc = NULL;
	ret = NULL;
	clnt = fid->clnt;

	/* if the offset is below or above the current response, free it */
	if (offset < fid->rdir_fpos \|\| (fid->rdir_fcall &&
	offset >= fid->rdir_fpos+fid->rdir_fcall->params.rread.count)) {
	fid->rdir_pos = 0;
	if (fid->rdir_fcall)
	fid->rdir_fpos += fid->rdir_fcall->params.rread.count;

	kfree(fid->rdir_fcall);
	fid->rdir_fcall = NULL;
	if (offset < fid->rdir_fpos)
	fid->rdir_fpos = 0;
	}

	if (!fid->rdir_fcall) {
	n = fid->iounit;
	if (!n \|\| n > clnt->msize-P9_IOHDRSZ)
	n = clnt->msize - P9_IOHDRSZ;

	while (1) {
	if (fid->rdir_fcall) {
	fid->rdir_fpos +=
	fid->rdir_fcall->params.rread.count;
	kfree(fid->rdir_fcall);
	fid->rdir_fcall = NULL;
	}

	tc = p9_create_tread(fid->fid, fid->rdir_fpos, n);
	if (IS_ERR(tc)) {
	err = PTR_ERR(tc);
	tc = NULL;
	goto error;
	}

	err = p9_client_rpc(clnt, tc, &rc);
	if (err)
	goto error;

	n = rc->params.rread.count;
	if (n == 0)
	goto done;

	fid->rdir_fcall = rc;
	rc = NULL;
	if (offset >= fid->rdir_fpos &&
	offset < fid->rdir_fpos+n)
	break;
	}

	fid->rdir_pos = 0;
	}

	m = offset - fid->rdir_fpos;
	if (m < 0)
	goto done;

	n = p9_deserialize_stat(fid->rdir_fcall->params.rread.data + m,
	fid->rdir_fcall->params.rread.count - m, &st, clnt->dotu);

	if (!n) {
	err = -EIO;
	goto error;
	}

	fid->rdir_pos += n;
	st.size = n;
	ret = p9_clone_stat(&st, clnt->dotu);
	if (IS_ERR(ret)) {
	err = PTR_ERR(ret);
	ret = NULL;
	goto error;
	}

	done:
	kfree(tc);
	kfree(rc);
	return ret;

	error:
	kfree(tc);
	kfree(rc);
	kfree(ret);
	return ERR_PTR(err);
	}
	EXPORT_SYMBOL(p9_client_dirread);

	static struct p9_stat p9_clone_stat(struct p9_stat st, int dotu)
	{
	int n;
	char *p;
	struct p9_stat *ret;

	n = sizeof(struct p9_stat) + st->name.len + st->uid.len + st->gid.len +
	st->muid.len;

	if (dotu)
	n += st->extension.len;

	ret = kmalloc(n, GFP_KERNEL);
	if (!ret)
	return ERR_PTR(-ENOMEM);

	memmove(ret, st, sizeof(struct p9_stat));
	p = ((char *) ret) + sizeof(struct p9_stat);
	memmove(p, st->name.str, st->name.len);
	ret->name.str = p;
	p += st->name.len;
	memmove(p, st->uid.str, st->uid.len);
	ret->uid.str = p;
	p += st->uid.len;
	memmove(p, st->gid.str, st->gid.len);
	ret->gid.str = p;
	p += st->gid.len;
	memmove(p, st->muid.str, st->muid.len);
	ret->muid.str = p;
	p += st->muid.len;

	if (dotu) {
	memmove(p, st->extension.str, st->extension.len);
	ret->extension.str = p;
	p += st->extension.len;
	}

	return ret;
	}

	static struct p9_fid p9_fid_create(struct p9_client clnt)
	{
	int err;
	struct p9_fid *fid;

	P9_DPRINTK(P9_DEBUG_9P, "clnt %p\n", clnt);
	fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
	if (!fid)
	return ERR_PTR(-ENOMEM);

	fid->fid = p9_idpool_get(clnt->fidpool);
	if (fid->fid < 0) {
	err = -ENOSPC;
	goto error;
	}

	memset(&fid->qid, 0, sizeof(struct p9_qid));
	fid->mode = -1;
	fid->rdir_fpos = 0;
	fid->rdir_pos = 0;
	fid->rdir_fcall = NULL;
	fid->uid = current->fsuid;
	fid->clnt = clnt;
	fid->aux = NULL;

	spin_lock(&clnt->lock);
	list_add(&fid->flist, &clnt->fidlist);
	spin_unlock(&clnt->lock);

	return fid;

	error:
	kfree(fid);
	return ERR_PTR(err);
	}

	static void p9_fid_destroy(struct p9_fid *fid)
	{
	struct p9_client *clnt;

	P9_DPRINTK(P9_DEBUG_9P, "fid %d\n", fid->fid);
	clnt = fid->clnt;
	p9_idpool_put(fid->fid, clnt->fidpool);
	spin_lock(&clnt->lock);
	list_del(&fid->flist);
	spin_unlock(&clnt->lock);
	kfree(fid->rdir_fcall);
	kfree(fid);
	}