9p: Reorganization of 9p file system code

This patchset moves non-filesystem interfaces of v9fs from fs/9p to net/9p.
It moves the transport, packet marshalling and connection layers to net/9p
leaving only the VFS related files in fs/9p.  This work is being done in
preparation for in-kernel 9p servers as well as alternate 9p clients (other
than VFS).

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 965 insertions, 0 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
new file mode 100644
index 000000000000..bb2b8a3af196
--- /dev/null
+++ b/net/9p/client.c
@@ -0,0 +1,965 @@
+/*
+ * net/9p/clnt.c
+ *
+ * 9P Client
+ *
+ *  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/idr.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <net/9p/9p.h>
+#include <net/9p/transport.h>
+#include <net/9p/conn.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);
+
+struct p9_client *p9_client_create(struct p9_transport *trans, int msize,
+								   int dotu)
+{
+	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);
+
+	P9_DPRINTK(P9_DEBUG_9P, "clnt %p trans %p msize %d dotu %d\n",
+		clnt, trans, msize, dotu);
+	spin_lock_init(&clnt->lock);
+	clnt->trans = trans;
+	clnt->msize = msize;
+	clnt->dotu = dotu;
+	INIT_LIST_HEAD(&clnt->fidlist);
+	clnt->fidpool = p9_idpool_create();
+	if (!clnt->fidpool) {
+		err = PTR_ERR(clnt->fidpool);
+		clnt->fidpool = NULL;
+		goto error;
+	}
+
+	clnt->conn = p9_conn_create(clnt->trans, clnt->msize, &clnt->dotu);
+	if (IS_ERR(clnt->conn)) {
+		err = PTR_ERR(clnt->conn);
+		clnt->conn = NULL;
+		goto error;
+	}
+
+	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_conn_rpc(clnt->conn, 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->conn) {
+		p9_conn_destroy(clnt->conn);
+		clnt->conn = NULL;
+	}
+
+	if (clnt->trans) {
+		clnt->trans->close(clnt->trans);
+		kfree(clnt->trans);
+		clnt->trans = NULL;
+	}
+
+	if (clnt->fidpool)
+		p9_idpool_destroy(clnt->fidpool);
+
+	list_for_each_entry_safe(fid, fidptr, &clnt->fidlist, flist)
+		p9_fid_destroy(fid);
+
+	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;
+	p9_conn_cancel(clnt->conn, -EIO);
+}
+EXPORT_SYMBOL(p9_client_disconnect);
+
+struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
+	char *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);
+	if (IS_ERR(tc)) {
+		err = PTR_ERR(tc);
+		tc = NULL;
+		goto error;
+	}
+
+	err = p9_conn_rpc(clnt->conn, 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, 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);
+	if (IS_ERR(tc)) {
+		err = PTR_ERR(tc);
+		tc = NULL;
+		goto error;
+	}
+
+	err = p9_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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_conn_rpc(clnt->conn, 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);
+	p += st->name.len;
+	memmove(p, st->uid.str, st->uid.len);
+	p += st->uid.len;
+	memmove(p, st->gid.str, st->gid.len);
+	p += st->gid.len;
+	memmove(p, st->muid.str, st->muid.len);
+	p += st->muid.len;
+
+	if (dotu) {
+		memmove(p, st->extension.str, st->extension.len);
+		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);
+}