text: /*
   * 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
   *
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #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/slab.h>
  #include <linux/sched/signal.h>
  #include <linux/uaccess.h>
  #include <linux/uio.h>
  #include <net/9p/9p.h>
  #include <linux/parser.h>
  #include <linux/seq_file.h>
  #include <net/9p/client.h>
  #include <net/9p/transport.h>
  #include "protocol.h"
  
  #define CREATE_TRACE_POINTS
  #include <trace/events/9p.h>
  
  /*
    * Client Option Parsing (code inspired by NFS code)
    *  - a little lazy - parse all client options
    */
  
  enum {
  	Opt_msize,
  	Opt_trans,
  	Opt_legacy,
  	Opt_version,
  	Opt_err,
  };
  
  static const match_table_t tokens = {
  	{Opt_msize, "msize=%u"},
  	{Opt_legacy, "noextend"},
  	{Opt_trans, "trans=%s"},
  	{Opt_version, "version=%s"},
  	{Opt_err, NULL},
  };
  
  inline int p9_is_proto_dotl(struct p9_client *clnt)
  {
  	return clnt->proto_version == p9_proto_2000L;
  }
  EXPORT_SYMBOL(p9_is_proto_dotl);
  
  inline int p9_is_proto_dotu(struct p9_client *clnt)
  {
  	return clnt->proto_version == p9_proto_2000u;
  }
  EXPORT_SYMBOL(p9_is_proto_dotu);
  
  int p9_show_client_options(struct seq_file *m, struct p9_client *clnt)
  {
  	if (clnt->msize != 8192)
  		seq_printf(m, ",msize=%u", clnt->msize);
  	seq_printf(m, ",trans=%s", clnt->trans_mod->name);
  
  	switch (clnt->proto_version) {
  	case p9_proto_legacy:
  		seq_puts(m, ",noextend");
  		break;
  	case p9_proto_2000u:
  		seq_puts(m, ",version=9p2000.u");
  		break;
  	case p9_proto_2000L:
  		/* Default */
  		break;
  	}
  
  	if (clnt->trans_mod->show_options)
  		return clnt->trans_mod->show_options(m, clnt);
  	return 0;
  }
  EXPORT_SYMBOL(p9_show_client_options);
  
  /*
   * Some error codes are taken directly from the server replies,
   * make sure they are valid.
   */
  static int safe_errno(int err)
  {
  	if ((err > 0) || (err < -MAX_ERRNO)) {
  		p9_debug(P9_DEBUG_ERROR, "Invalid error code %d\n", err);
  		return -EPROTO;
  	}
  	return err;
  }
  
  
  /* Interpret mount option for protocol version */
  static int get_protocol_version(char *s)
  {
  	int version = -EINVAL;
  
  	if (!strcmp(s, "9p2000")) {
  		version = p9_proto_legacy;
  		p9_debug(P9_DEBUG_9P, "Protocol version: Legacy\n");
  	} else if (!strcmp(s, "9p2000.u")) {
  		version = p9_proto_2000u;
  		p9_debug(P9_DEBUG_9P, "Protocol version: 9P2000.u\n");
  	} else if (!strcmp(s, "9p2000.L")) {
  		version = p9_proto_2000L;
  		p9_debug(P9_DEBUG_9P, "Protocol version: 9P2000.L\n");
  	} else
  		pr_info("Unknown protocol version %s\n", s);
  
  	return version;
  }
  
  /**
   * parse_options - parse mount options into client structure
   * @opts: options string passed from mount
   * @clnt: existing v9fs client information
   *
   * Return 0 upon success, -ERRNO upon failure
   */
  
  static int parse_opts(char *opts, struct p9_client *clnt)
  {
  	char *options, *tmp_options;
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  	int option;
  	char *s;
  	int ret = 0;
  
  	clnt->proto_version = p9_proto_2000L;
  	clnt->msize = 8192;
  
  	if (!opts)
  		return 0;
  
  	tmp_options = kstrdup(opts, GFP_KERNEL);
  	if (!tmp_options) {
  		p9_debug(P9_DEBUG_ERROR,
  			 "failed to allocate copy of option string\n");
  		return -ENOMEM;
  	}
  	options = tmp_options;
  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token, r;
  		if (!*p)
  			continue;
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_msize:
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?\n");
  				ret = r;
  				continue;
  			}
  			if (option < 4096) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "msize should be at least 4k\n");
  				ret = -EINVAL;
  				continue;
  			}
  			clnt->msize = option;
  			break;
  		case Opt_trans:
  			s = match_strdup(&args[0]);
  			if (!s) {
  				ret = -ENOMEM;
  				p9_debug(P9_DEBUG_ERROR,
  					 "problem allocating copy of trans arg\n");
  				goto free_and_return;
  			}
  
  			v9fs_put_trans(clnt->trans_mod);
  			clnt->trans_mod = v9fs_get_trans_by_name(s);
  			if (clnt->trans_mod == NULL) {
  				pr_info("Could not find request transport: %s\n",
  					s);
  				ret = -EINVAL;
  			}
  			kfree(s);
  			break;
  		case Opt_legacy:
  			clnt->proto_version = p9_proto_legacy;
  			break;
  		case Opt_version:
  			s = match_strdup(&args[0]);
  			if (!s) {
  				ret = -ENOMEM;
  				p9_debug(P9_DEBUG_ERROR,
  					 "problem allocating copy of version arg\n");
  				goto free_and_return;
  			}
  			r = get_protocol_version(s);
  			if (r < 0)
  				ret = r;
  			else
  				clnt->proto_version = r;
  			kfree(s);
  			break;
  		default:
  			continue;
  		}
  	}
  
  free_and_return:
  	if (ret)
  		v9fs_put_trans(clnt->trans_mod);
  	kfree(tmp_options);
  	return ret;
  }
  
  static int p9_fcall_init(struct p9_client *c, struct p9_fcall *fc,
  			 int alloc_msize)
  {
  	if (likely(c->fcall_cache) && alloc_msize == c->msize) {
  		fc->sdata = kmem_cache_alloc(c->fcall_cache, GFP_NOFS);
  		fc->cache = c->fcall_cache;
  	} else {
  		fc->sdata = kmalloc(alloc_msize, GFP_NOFS);
  		fc->cache = NULL;
  	}
  	if (!fc->sdata)
  		return -ENOMEM;
  	fc->capacity = alloc_msize;
  	return 0;
  }
  
  void p9_fcall_fini(struct p9_fcall *fc)
  {
  	/* sdata can be NULL for interrupted requests in trans_rdma,
  	 * and kmem_cache_free does not do NULL-check for us
  	 */
  	if (unlikely(!fc->sdata))
  		return;
  
  	if (fc->cache)
  		kmem_cache_free(fc->cache, fc->sdata);
  	else
  		kfree(fc->sdata);
  }
  EXPORT_SYMBOL(p9_fcall_fini);
  
  static struct kmem_cache *p9_req_cache;
  
  /**
   * p9_req_alloc - Allocate a new request.
   * @c: Client session.
   * @type: Transaction type.
   * @max_size: Maximum packet size for this request.
   *
   * Context: Process context.
   * Return: Pointer to new request.
   */
  static struct p9_req_t *
  p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size)
  {
  	struct p9_req_t *req = kmem_cache_alloc(p9_req_cache, GFP_NOFS);
  	int alloc_msize = min(c->msize, max_size);
  	int tag;
  
  	if (!req)
  		return ERR_PTR(-ENOMEM);
  
  	if (p9_fcall_init(c, &req->tc, alloc_msize))
  		goto free_req;
  	if (p9_fcall_init(c, &req->rc, alloc_msize))
  		goto free;
  
  	p9pdu_reset(&req->tc);
  	p9pdu_reset(&req->rc);
  	req->status = REQ_STATUS_ALLOC;
  	init_waitqueue_head(&req->wq);
  	INIT_LIST_HEAD(&req->req_list);
  
  	idr_preload(GFP_NOFS);
  	spin_lock_irq(&c->lock);
  	if (type == P9_TVERSION)
  		tag = idr_alloc(&c->reqs, req, P9_NOTAG, P9_NOTAG + 1,
  				GFP_NOWAIT);
  	else
  		tag = idr_alloc(&c->reqs, req, 0, P9_NOTAG, GFP_NOWAIT);
  	req->tc.tag = tag;
  	spin_unlock_irq(&c->lock);
  	idr_preload_end();
  	if (tag < 0)
  		goto free;
  
  	/* Init ref to two because in the general case there is one ref
  	 * that is put asynchronously by a writer thread, one ref
  	 * temporarily given by p9_tag_lookup and put by p9_client_cb
  	 * in the recv thread, and one ref put by p9_tag_remove in the
  	 * main thread. The only exception is virtio that does not use
  	 * p9_tag_lookup but does not have a writer thread either
  	 * (the write happens synchronously in the request/zc_request
  	 * callback), so p9_client_cb eats the second ref there
  	 * as the pointer is duplicated directly by virtqueue_add_sgs()
  	 */
  	refcount_set(&req->refcount.refcount, 2);
  
  	return req;
  
  free:
  	p9_fcall_fini(&req->tc);
  	p9_fcall_fini(&req->rc);
  free_req:
  	kmem_cache_free(p9_req_cache, req);
  	return ERR_PTR(-ENOMEM);
  }
  
  /**
   * p9_tag_lookup - Look up a request by tag.
   * @c: Client session.
   * @tag: Transaction ID.
   *
   * Context: Any context.
   * Return: A request, or %NULL if there is no request with that tag.
   */
  struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag)
  {
  	struct p9_req_t *req;
  
  	rcu_read_lock();
  again:
  	req = idr_find(&c->reqs, tag);
  	if (req) {
  		/* We have to be careful with the req found under rcu_read_lock
  		 * Thanks to SLAB_TYPESAFE_BY_RCU we can safely try to get the
  		 * ref again without corrupting other data, then check again
  		 * that the tag matches once we have the ref
  		 */
  		if (!p9_req_try_get(req))
  			goto again;
  		if (req->tc.tag != tag) {
  			p9_req_put(req);
  			goto again;
  		}
  	}
  	rcu_read_unlock();
  
  	return req;
  }
  EXPORT_SYMBOL(p9_tag_lookup);
  
  /**
   * p9_tag_remove - Remove a tag.
   * @c: Client session.
   * @r: Request of reference.
   *
   * Context: Any context.
   */
  static int p9_tag_remove(struct p9_client *c, struct p9_req_t *r)
  {
  	unsigned long flags;
  	u16 tag = r->tc.tag;
  
  	p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag);
  	spin_lock_irqsave(&c->lock, flags);
  	idr_remove(&c->reqs, tag);
  	spin_unlock_irqrestore(&c->lock, flags);
  	return p9_req_put(r);
  }
  
  static void p9_req_free(struct kref *ref)
  {
  	struct p9_req_t *r = container_of(ref, struct p9_req_t, refcount);
  	p9_fcall_fini(&r->tc);
  	p9_fcall_fini(&r->rc);
  	kmem_cache_free(p9_req_cache, r);
  }
  
  int p9_req_put(struct p9_req_t *r)
  {
  	return kref_put(&r->refcount, p9_req_free);
  }
  EXPORT_SYMBOL(p9_req_put);
  
  /**
   * p9_tag_cleanup - cleans up tags structure and reclaims resources
   * @c:  v9fs client struct
   *
   * This frees resources associated with the tags structure
   *
   */
  static void p9_tag_cleanup(struct p9_client *c)
  {
  	struct p9_req_t *req;
  	int id;
  
  	rcu_read_lock();
  	idr_for_each_entry(&c->reqs, req, id) {
  		pr_info("Tag %d still in use\n", id);
  		if (p9_tag_remove(c, req) == 0)
  			pr_warn("Packet with tag %d has still references",
  				req->tc.tag);
  	}
  	rcu_read_unlock();
  }
  
  /**
   * p9_client_cb - call back from transport to client
   * c: client state
   * req: request received
   *
   */
  void p9_client_cb(struct p9_client *c, struct p9_req_t *req, int status)
  {
  	p9_debug(P9_DEBUG_MUX, " tag %d\n", req->tc.tag);
  
  	/*
  	 * This barrier is needed to make sure any change made to req before
  	 * the status change is visible to another thread
  	 */
  	smp_wmb();
  	req->status = status;
  
  	wake_up(&req->wq);
  	p9_debug(P9_DEBUG_MUX, "wakeup: %d\n", req->tc.tag);
  	p9_req_put(req);
  }
  EXPORT_SYMBOL(p9_client_cb);
  
  /**
   * p9_parse_header - parse header arguments out of a packet
   * @pdu: packet to parse
   * @size: size of packet
   * @type: type of request
   * @tag: tag of packet
   * @rewind: set if we need to rewind offset afterwards
   */
  
  int
  p9_parse_header(struct p9_fcall *pdu, int32_t *size, int8_t *type, int16_t *tag,
  								int rewind)
  {
  	int8_t r_type;
  	int16_t r_tag;
  	int32_t r_size;
  	int offset = pdu->offset;
  	int err;
  
  	pdu->offset = 0;
  
  	err = p9pdu_readf(pdu, 0, "dbw", &r_size, &r_type, &r_tag);
  	if (err)
  		goto rewind_and_exit;
  
  	if (type)
  		*type = r_type;
  	if (tag)
  		*tag = r_tag;
  	if (size)
  		*size = r_size;
  
  	if (pdu->size != r_size || r_size < 7) {
  		err = -EINVAL;
  		goto rewind_and_exit;
  	}
  
  	pdu->id = r_type;
  	pdu->tag = r_tag;
  
  	p9_debug(P9_DEBUG_9P, "<<< size=%d type: %d tag: %d\n",
  		 pdu->size, pdu->id, pdu->tag);
  
  rewind_and_exit:
  	if (rewind)
  		pdu->offset = offset;
  	return err;
  }
  EXPORT_SYMBOL(p9_parse_header);
  
  /**
   * p9_check_errors - check 9p packet for error return and process it
   * @c: current client instance
   * @req: request to parse and check for error conditions
   *
   * returns error code if one is discovered, otherwise returns 0
   *
   * this will have to be more complicated if we have multiple
   * error packet types
   */
  
  static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
  {
  	int8_t type;
  	int err;
  	int ecode;
  
  	err = p9_parse_header(&req->rc, NULL, &type, NULL, 0);
  	if (req->rc.size >= c->msize) {
  		p9_debug(P9_DEBUG_ERROR,
  			 "requested packet size too big: %d\n",
  			 req->rc.size);
  		return -EIO;
  	}
  	/*
  	 * dump the response from server
  	 * This should be after check errors which poplulate pdu_fcall.
  	 */
  	trace_9p_protocol_dump(c, &req->rc);
  	if (err) {
  		p9_debug(P9_DEBUG_ERROR, "couldn't parse header %d\n", err);
  		return err;
  	}
  	if (type != P9_RERROR && type != P9_RLERROR)
  		return 0;
  
  	if (!p9_is_proto_dotl(c)) {
  		char *ename;
  		err = p9pdu_readf(&req->rc, c->proto_version, "s?d",
  				  &ename, &ecode);
  		if (err)
  			goto out_err;
  
  		if (p9_is_proto_dotu(c) && ecode < 512)
  			err = -ecode;
  
  		if (!err) {
  			err = p9_errstr2errno(ename, strlen(ename));
  
  			p9_debug(P9_DEBUG_9P, "<<< RERROR (%d) %s\n",
  				 -ecode, ename);
  		}
  		kfree(ename);
  	} else {
  		err = p9pdu_readf(&req->rc, c->proto_version, "d", &ecode);
  		err = -ecode;
  
  		p9_debug(P9_DEBUG_9P, "<<< RLERROR (%d)\n", -ecode);
  	}
  
  	return err;
  
  out_err:
  	p9_debug(P9_DEBUG_ERROR, "couldn't parse error%d\n", err);
  
  	return err;
  }
  
  /**
   * p9_check_zc_errors - check 9p packet for error return and process it
   * @c: current client instance
   * @req: request to parse and check for error conditions
   * @in_hdrlen: Size of response protocol buffer.
   *
   * returns error code if one is discovered, otherwise returns 0
   *
   * this will have to be more complicated if we have multiple
   * error packet types
   */
  
  static int p9_check_zc_errors(struct p9_client *c, struct p9_req_t *req,
  			      struct iov_iter *uidata, int in_hdrlen)
  {
  	int err;
  	int ecode;
  	int8_t type;
  	char *ename = NULL;
  
  	err = p9_parse_header(&req->rc, NULL, &type, NULL, 0);
  	/*
  	 * dump the response from server
  	 * This should be after parse_header which poplulate pdu_fcall.
  	 */
  	trace_9p_protocol_dump(c, &req->rc);
  	if (err) {
  		p9_debug(P9_DEBUG_ERROR, "couldn't parse header %d\n", err);
  		return err;
  	}
  
  	if (type != P9_RERROR && type != P9_RLERROR)
  		return 0;
  
  	if (!p9_is_proto_dotl(c)) {
  		/* Error is reported in string format */
  		int len;
  		/* 7 = header size for RERROR; */
  		int inline_len = in_hdrlen - 7;
  
  		len = req->rc.size - req->rc.offset;
  		if (len > (P9_ZC_HDR_SZ - 7)) {
  			err = -EFAULT;
  			goto out_err;
  		}
  
  		ename = &req->rc.sdata[req->rc.offset];
  		if (len > inline_len) {
  			/* We have error in external buffer */
  			if (!copy_from_iter_full(ename + inline_len,
  					     len - inline_len, uidata)) {
  				err = -EFAULT;
  				goto out_err;
  			}
  		}
  		ename = NULL;
  		err = p9pdu_readf(&req->rc, c->proto_version, "s?d",
  				  &ename, &ecode);
  		if (err)
  			goto out_err;
  
  		if (p9_is_proto_dotu(c) && ecode < 512)
  			err = -ecode;
  
  		if (!err) {
  			err = p9_errstr2errno(ename, strlen(ename));
  
  			p9_debug(P9_DEBUG_9P, "<<< RERROR (%d) %s\n",
  				 -ecode, ename);
  		}
  		kfree(ename);
  	} else {
  		err = p9pdu_readf(&req->rc, c->proto_version, "d", &ecode);
  		err = -ecode;
  
  		p9_debug(P9_DEBUG_9P, "<<< RLERROR (%d)\n", -ecode);
  	}
  	return err;
  
  out_err:
  	p9_debug(P9_DEBUG_ERROR, "couldn't parse error%d\n", err);
  	return err;
  }
  
  static struct p9_req_t *
  p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...);
  
  /**
   * p9_client_flush - flush (cancel) a request
   * @c: client state
   * @oldreq: request to cancel
   *
   * This sents a flush for a particular request and links
   * the flush request to the original request.  The current
   * code only supports a single flush request although the protocol
   * allows for multiple flush requests to be sent for a single request.
   *
   */
  
  static int p9_client_flush(struct p9_client *c, struct p9_req_t *oldreq)
  {
  	struct p9_req_t *req;
  	int16_t oldtag;
  	int err;
  
  	err = p9_parse_header(&oldreq->tc, NULL, NULL, &oldtag, 1);
  	if (err)
  		return err;
  
  	p9_debug(P9_DEBUG_9P, ">>> TFLUSH tag %d\n", oldtag);
  
  	req = p9_client_rpc(c, P9_TFLUSH, "w", oldtag);
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	/*
  	 * if we haven't received a response for oldreq,
  	 * remove it from the list
  	 */
  	if (oldreq->status == REQ_STATUS_SENT) {
  		if (c->trans_mod->cancelled)
  			c->trans_mod->cancelled(c, oldreq);
  	}
  
  	p9_tag_remove(c, req);
  	return 0;
  }
  
  static struct p9_req_t *p9_client_prepare_req(struct p9_client *c,
  					      int8_t type, int req_size,
  					      const char *fmt, va_list ap)
  {
  	int err;
  	struct p9_req_t *req;
  
  	p9_debug(P9_DEBUG_MUX, "client %p op %d\n", c, type);
  
  	/* we allow for any status other than disconnected */
  	if (c->status == Disconnected)
  		return ERR_PTR(-EIO);
  
  	/* if status is begin_disconnected we allow only clunk request */
  	if ((c->status == BeginDisconnect) && (type != P9_TCLUNK))
  		return ERR_PTR(-EIO);
  
  	req = p9_tag_alloc(c, type, req_size);
  	if (IS_ERR(req))
  		return req;
  
  	/* marshall the data */
  	p9pdu_prepare(&req->tc, req->tc.tag, type);
  	err = p9pdu_vwritef(&req->tc, c->proto_version, fmt, ap);
  	if (err)
  		goto reterr;
  	p9pdu_finalize(c, &req->tc);
  	trace_9p_client_req(c, type, req->tc.tag);
  	return req;
  reterr:
  	p9_tag_remove(c, req);
  	/* We have to put also the 2nd reference as it won't be used */
  	p9_req_put(req);
  	return ERR_PTR(err);
  }
  
  /**
   * p9_client_rpc - issue a request and wait for a response
   * @c: client session
   * @type: type of request
   * @fmt: protocol format string (see protocol.c)
   *
   * Returns request structure (which client must free using p9_tag_remove)
   */
  
  static struct p9_req_t *
  p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
  {
  	va_list ap;
  	int sigpending, err;
  	unsigned long flags;
  	struct p9_req_t *req;
  
  	va_start(ap, fmt);
  	req = p9_client_prepare_req(c, type, c->msize, fmt, ap);
  	va_end(ap);
  	if (IS_ERR(req))
  		return req;
  
  	if (signal_pending(current)) {
  		sigpending = 1;
  		clear_thread_flag(TIF_SIGPENDING);
  	} else
  		sigpending = 0;
  
  	err = c->trans_mod->request(c, req);
  	if (err < 0) {
  		/* write won't happen */
  		p9_req_put(req);
  		if (err != -ERESTARTSYS && err != -EFAULT)
  			c->status = Disconnected;
  		goto recalc_sigpending;
  	}
  again:
  	/* Wait for the response */
  	err = wait_event_killable(req->wq, req->status >= REQ_STATUS_RCVD);
  
  	/*
  	 * Make sure our req is coherent with regard to updates in other
  	 * threads - echoes to wmb() in the callback
  	 */
  	smp_rmb();
  
  	if ((err == -ERESTARTSYS) && (c->status == Connected)
  				  && (type == P9_TFLUSH)) {
  		sigpending = 1;
  		clear_thread_flag(TIF_SIGPENDING);
  		goto again;
  	}
  
  	if (req->status == REQ_STATUS_ERROR) {
  		p9_debug(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
  		err = req->t_err;
  	}
  	if ((err == -ERESTARTSYS) && (c->status == Connected)) {
  		p9_debug(P9_DEBUG_MUX, "flushing\n");
  		sigpending = 1;
  		clear_thread_flag(TIF_SIGPENDING);
  
  		if (c->trans_mod->cancel(c, req))
  			p9_client_flush(c, req);
  
  		/* if we received the response anyway, don't signal error */
  		if (req->status == REQ_STATUS_RCVD)
  			err = 0;
  	}
  recalc_sigpending:
  	if (sigpending) {
  		spin_lock_irqsave(&current->sighand->siglock, flags);
  		recalc_sigpending();
  		spin_unlock_irqrestore(&current->sighand->siglock, flags);
  	}
  	if (err < 0)
  		goto reterr;
  
  	err = p9_check_errors(c, req);
  	trace_9p_client_res(c, type, req->rc.tag, err);
  	if (!err)
  		return req;
  reterr:
  	p9_tag_remove(c, req);
  	return ERR_PTR(safe_errno(err));
  }
  
  /**
   * p9_client_zc_rpc - issue a request and wait for a response
   * @c: client session
   * @type: type of request
   * @uidata: destination for zero copy read
   * @uodata: source for zero copy write
   * @inlen: read buffer size
   * @olen: write buffer size
   * @hdrlen: reader header size, This is the size of response protocol data
   * @fmt: protocol format string (see protocol.c)
   *
   * Returns request structure (which client must free using p9_tag_remove)
   */
  static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
  					 struct iov_iter *uidata,
  					 struct iov_iter *uodata,
  					 int inlen, int olen, int in_hdrlen,
  					 const char *fmt, ...)
  {
  	va_list ap;
  	int sigpending, err;
  	unsigned long flags;
  	struct p9_req_t *req;
  
  	va_start(ap, fmt);
  	/*
  	 * We allocate a inline protocol data of only 4k bytes.
  	 * The actual content is passed in zero-copy fashion.
  	 */
  	req = p9_client_prepare_req(c, type, P9_ZC_HDR_SZ, fmt, ap);
  	va_end(ap);
  	if (IS_ERR(req))
  		return req;
  
  	if (signal_pending(current)) {
  		sigpending = 1;
  		clear_thread_flag(TIF_SIGPENDING);
  	} else
  		sigpending = 0;
  
  	err = c->trans_mod->zc_request(c, req, uidata, uodata,
  				       inlen, olen, in_hdrlen);
  	if (err < 0) {
  		if (err == -EIO)
  			c->status = Disconnected;
  		if (err != -ERESTARTSYS)
  			goto recalc_sigpending;
  	}
  	if (req->status == REQ_STATUS_ERROR) {
  		p9_debug(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
  		err = req->t_err;
  	}
  	if ((err == -ERESTARTSYS) && (c->status == Connected)) {
  		p9_debug(P9_DEBUG_MUX, "flushing\n");
  		sigpending = 1;
  		clear_thread_flag(TIF_SIGPENDING);
  
  		if (c->trans_mod->cancel(c, req))
  			p9_client_flush(c, req);
  
  		/* if we received the response anyway, don't signal error */
  		if (req->status == REQ_STATUS_RCVD)
  			err = 0;
  	}
  recalc_sigpending:
  	if (sigpending) {
  		spin_lock_irqsave(&current->sighand->siglock, flags);
  		recalc_sigpending();
  		spin_unlock_irqrestore(&current->sighand->siglock, flags);
  	}
  	if (err < 0)
  		goto reterr;
  
  	err = p9_check_zc_errors(c, req, uidata, in_hdrlen);
  	trace_9p_client_res(c, type, req->rc.tag, err);
  	if (!err)
  		return req;
  reterr:
  	p9_tag_remove(c, req);
  	return ERR_PTR(safe_errno(err));
  }
  
  static struct p9_fid *p9_fid_create(struct p9_client *clnt)
  {
  	int ret;
  	struct p9_fid *fid;
  
  	p9_debug(P9_DEBUG_FID, "clnt %p\n", clnt);
  	fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
  	if (!fid)
  		return NULL;
  
  	memset(&fid->qid, 0, sizeof(struct p9_qid));
  	fid->mode = -1;
  	fid->uid = current_fsuid();
  	fid->clnt = clnt;
  	fid->rdir = NULL;
  	fid->fid = 0;
  
  	idr_preload(GFP_KERNEL);
  	spin_lock_irq(&clnt->lock);
  	ret = idr_alloc_u32(&clnt->fids, fid, &fid->fid, P9_NOFID - 1,
  			    GFP_NOWAIT);
  	spin_unlock_irq(&clnt->lock);
  	idr_preload_end();
  
  	if (!ret)
  		return fid;
  
  	kfree(fid);
  	return NULL;
  }
  
  static void p9_fid_destroy(struct p9_fid *fid)
  {
  	struct p9_client *clnt;
  	unsigned long flags;
  
  	p9_debug(P9_DEBUG_FID, "fid %d\n", fid->fid);
  	clnt = fid->clnt;
  	spin_lock_irqsave(&clnt->lock, flags);
  	idr_remove(&clnt->fids, fid->fid);
  	spin_unlock_irqrestore(&clnt->lock, flags);
  	kfree(fid->rdir);
  	kfree(fid);
  }
  
  static int p9_client_version(struct p9_client *c)
  {
  	int err = 0;
  	struct p9_req_t *req;
  	char *version = NULL;
  	int msize;
  
  	p9_debug(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
  		 c->msize, c->proto_version);
  
  	switch (c->proto_version) {
  	case p9_proto_2000L:
  		req = p9_client_rpc(c, P9_TVERSION, "ds",
  					c->msize, "9P2000.L");
  		break;
  	case p9_proto_2000u:
  		req = p9_client_rpc(c, P9_TVERSION, "ds",
  					c->msize, "9P2000.u");
  		break;
  	case p9_proto_legacy:
  		req = p9_client_rpc(c, P9_TVERSION, "ds",
  					c->msize, "9P2000");
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	err = p9pdu_readf(&req->rc, c->proto_version, "ds", &msize, &version);
  	if (err) {
  		p9_debug(P9_DEBUG_9P, "version error %d\n", err);
  		trace_9p_protocol_dump(c, &req->rc);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RVERSION msize %d %s\n", msize, version);
  	if (!strncmp(version, "9P2000.L", 8))
  		c->proto_version = p9_proto_2000L;
  	else if (!strncmp(version, "9P2000.u", 8))
  		c->proto_version = p9_proto_2000u;
  	else if (!strncmp(version, "9P2000", 6))
  		c->proto_version = p9_proto_legacy;
  	else {
  		p9_debug(P9_DEBUG_ERROR,
  			 "server returned an unknown version: %s\n", version);
  		err = -EREMOTEIO;
  		goto error;
  	}
  
  	if (msize < 4096) {
  		p9_debug(P9_DEBUG_ERROR,
  			 "server returned a msize < 4096: %d\n", msize);
  		err = -EREMOTEIO;
  		goto error;
  	}
  	if (msize < c->msize)
  		c->msize = msize;
  
  error:
  	kfree(version);
  	p9_tag_remove(c, req);
  
  	return err;
  }
  
  struct p9_client *p9_client_create(const char *dev_name, char *options)
  {
  	int err;
  	struct p9_client *clnt;
  	char *client_id;
  
  	err = 0;
  	clnt = kmalloc(sizeof(struct p9_client), GFP_KERNEL);
  	if (!clnt)
  		return ERR_PTR(-ENOMEM);
  
  	clnt->trans_mod = NULL;
  	clnt->trans = NULL;
  	clnt->fcall_cache = NULL;
  
  	client_id = utsname()->nodename;
  	memcpy(clnt->name, client_id, strlen(client_id) + 1);
  
  	spin_lock_init(&clnt->lock);
  	idr_init(&clnt->fids);
  	idr_init(&clnt->reqs);
  
  	err = parse_opts(options, clnt);
  	if (err < 0)
  		goto free_client;
  
  	if (!clnt->trans_mod)
  		clnt->trans_mod = v9fs_get_default_trans();
  
  	if (clnt->trans_mod == NULL) {
  		err = -EPROTONOSUPPORT;
  		p9_debug(P9_DEBUG_ERROR,
  			 "No transport defined or default transport\n");
  		goto free_client;
  	}
  
  	p9_debug(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n",
  		 clnt, clnt->trans_mod, clnt->msize, clnt->proto_version);
  
  	err = clnt->trans_mod->create(clnt, dev_name, options);
  	if (err)
  		goto put_trans;
  
  	if (clnt->msize > clnt->trans_mod->maxsize)
  		clnt->msize = clnt->trans_mod->maxsize;
  
  	if (clnt->msize < 4096) {
  		p9_debug(P9_DEBUG_ERROR,
  			 "Please specify a msize of at least 4k\n");
  		err = -EINVAL;
  		goto free_client;
  	}
  
  	err = p9_client_version(clnt);
  	if (err)
  		goto close_trans;
  
  	/* P9_HDRSZ + 4 is the smallest packet header we can have that is
  	 * followed by data accessed from userspace by read
  	 */
  	clnt->fcall_cache =
  		kmem_cache_create_usercopy("9p-fcall-cache", clnt->msize,
  					   0, 0, P9_HDRSZ + 4,
  					   clnt->msize - (P9_HDRSZ + 4),
  					   NULL);
  
  	return clnt;
  
  close_trans:
  	clnt->trans_mod->close(clnt);
  put_trans:
  	v9fs_put_trans(clnt->trans_mod);
  free_client:
  	kfree(clnt);
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(p9_client_create);
  
  void p9_client_destroy(struct p9_client *clnt)
  {
  	struct p9_fid *fid;
  	int id;
  
  	p9_debug(P9_DEBUG_MUX, "clnt %p\n", clnt);
  
  	if (clnt->trans_mod)
  		clnt->trans_mod->close(clnt);
  
  	v9fs_put_trans(clnt->trans_mod);
  
  	idr_for_each_entry(&clnt->fids, fid, id) {
  		pr_info("Found fid %d not clunked\n", fid->fid);
  		p9_fid_destroy(fid);
  	}
  
  	p9_tag_cleanup(clnt);
  
  	kmem_cache_destroy(clnt->fcall_cache);
  	kfree(clnt);
  }
  EXPORT_SYMBOL(p9_client_destroy);
  
  void p9_client_disconnect(struct p9_client *clnt)
  {
  	p9_debug(P9_DEBUG_9P, "clnt %p\n", clnt);
  	clnt->status = Disconnected;
  }
  EXPORT_SYMBOL(p9_client_disconnect);
  
  void p9_client_begin_disconnect(struct p9_client *clnt)
  {
  	p9_debug(P9_DEBUG_9P, "clnt %p\n", clnt);
  	clnt->status = BeginDisconnect;
  }
  EXPORT_SYMBOL(p9_client_begin_disconnect);
  
  struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
  	const char *uname, kuid_t n_uname, const char *aname)
  {
  	int err = 0;
  	struct p9_req_t *req;
  	struct p9_fid *fid;
  	struct p9_qid qid;
  
  
  	p9_debug(P9_DEBUG_9P, ">>> TATTACH afid %d uname %s aname %s\n",
  		 afid ? afid->fid : -1, uname, aname);
  	fid = p9_fid_create(clnt);
  	if (!fid) {
  		err = -ENOMEM;
  		goto error;
  	}
  	fid->uid = n_uname;
  
  	req = p9_client_rpc(clnt, P9_TATTACH, "ddss?u", fid->fid,
  			afid ? afid->fid : P9_NOFID, uname, aname, n_uname);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Q", &qid);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		p9_tag_remove(clnt, req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RATTACH qid %x.%llx.%x\n",
  		 qid.type, (unsigned long long)qid.path, qid.version);
  
  	memmove(&fid->qid, &qid, sizeof(struct p9_qid));
  
  	p9_tag_remove(clnt, req);
  	return fid;
  
  error:
  	if (fid)
  		p9_fid_destroy(fid);
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(p9_client_attach);
  
  struct p9_fid *p9_client_walk(struct p9_fid *oldfid, uint16_t nwname,
  		const unsigned char * const *wnames, int clone)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_fid *fid;
  	struct p9_qid *wqids;
  	struct p9_req_t *req;
  	uint16_t nwqids, count;
  
  	err = 0;
  	wqids = NULL;
  	clnt = oldfid->clnt;
  	if (clone) {
  		fid = p9_fid_create(clnt);
  		if (!fid) {
  			err = -ENOMEM;
  			goto error;
  		}
  
  		fid->uid = oldfid->uid;
  	} else
  		fid = oldfid;
  
  
  	p9_debug(P9_DEBUG_9P, ">>> TWALK fids %d,%d nwname %ud wname[0] %s\n",
  		 oldfid->fid, fid->fid, nwname, wnames ? wnames[0] : NULL);
  
  	req = p9_client_rpc(clnt, P9_TWALK, "ddT", oldfid->fid, fid->fid,
  								nwname, wnames);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "R", &nwqids, &wqids);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		p9_tag_remove(clnt, req);
  		goto clunk_fid;
  	}
  	p9_tag_remove(clnt, req);
  
  	p9_debug(P9_DEBUG_9P, "<<< RWALK nwqid %d:\n", nwqids);
  
  	if (nwqids != nwname) {
  		err = -ENOENT;
  		goto clunk_fid;
  	}
  
  	for (count = 0; count < nwqids; count++)
  		p9_debug(P9_DEBUG_9P, "<<<     [%d] %x.%llx.%x\n",
  			count, wqids[count].type,
  			(unsigned long long)wqids[count].path,
  			wqids[count].version);
  
  	if (nwname)
  		memmove(&fid->qid, &wqids[nwqids - 1], sizeof(struct p9_qid));
  	else
  		fid->qid = oldfid->qid;
  
  	kfree(wqids);
  	return fid;
  
  clunk_fid:
  	kfree(wqids);
  	p9_client_clunk(fid);
  	fid = NULL;
  
  error:
  	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_client *clnt;
  	struct p9_req_t *req;
  	struct p9_qid qid;
  	int iounit;
  
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> %s fid %d mode %d\n",
  		p9_is_proto_dotl(clnt) ? "TLOPEN" : "TOPEN", fid->fid, mode);
  	err = 0;
  
  	if (fid->mode != -1)
  		return -EINVAL;
  
  	if (p9_is_proto_dotl(clnt))
  		req = p9_client_rpc(clnt, P9_TLOPEN, "dd", fid->fid, mode);
  	else
  		req = p9_client_rpc(clnt, P9_TOPEN, "db", fid->fid, mode);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Qd", &qid, &iounit);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto free_and_error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< %s qid %x.%llx.%x iounit %x\n",
  		p9_is_proto_dotl(clnt) ? "RLOPEN" : "ROPEN",  qid.type,
  		(unsigned long long)qid.path, qid.version, iounit);
  
  	fid->mode = mode;
  	fid->iounit = iounit;
  
  free_and_error:
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_open);
  
  int p9_client_create_dotl(struct p9_fid *ofid, const char *name, u32 flags, u32 mode,
  		kgid_t gid, struct p9_qid *qid)
  {
  	int err = 0;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  	int iounit;
  
  	p9_debug(P9_DEBUG_9P,
  			">>> TLCREATE fid %d name %s flags %d mode %d gid %d\n",
  			ofid->fid, name, flags, mode,
  		 	from_kgid(&init_user_ns, gid));
  	clnt = ofid->clnt;
  
  	if (ofid->mode != -1)
  		return -EINVAL;
  
  	req = p9_client_rpc(clnt, P9_TLCREATE, "dsddg", ofid->fid, name, flags,
  			mode, gid);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Qd", qid, &iounit);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto free_and_error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RLCREATE qid %x.%llx.%x iounit %x\n",
  			qid->type,
  			(unsigned long long)qid->path,
  			qid->version, iounit);
  
  	ofid->mode = mode;
  	ofid->iounit = iounit;
  
  free_and_error:
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_create_dotl);
  
  int p9_client_fcreate(struct p9_fid *fid, const char *name, u32 perm, int mode,
  		     char *extension)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  	struct p9_qid qid;
  	int iounit;
  
  	p9_debug(P9_DEBUG_9P, ">>> TCREATE fid %d name %s perm %d mode %d\n",
  						fid->fid, name, perm, mode);
  	err = 0;
  	clnt = fid->clnt;
  
  	if (fid->mode != -1)
  		return -EINVAL;
  
  	req = p9_client_rpc(clnt, P9_TCREATE, "dsdb?s", fid->fid, name, perm,
  				mode, extension);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Qd", &qid, &iounit);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto free_and_error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RCREATE qid %x.%llx.%x iounit %x\n",
  				qid.type,
  				(unsigned long long)qid.path,
  				qid.version, iounit);
  
  	fid->mode = mode;
  	fid->iounit = iounit;
  
  free_and_error:
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_fcreate);
  
  int p9_client_symlink(struct p9_fid *dfid, const char *name,
  		const char *symtgt, kgid_t gid, struct p9_qid *qid)
  {
  	int err = 0;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	p9_debug(P9_DEBUG_9P, ">>> TSYMLINK dfid %d name %s  symtgt %s\n",
  			dfid->fid, name, symtgt);
  	clnt = dfid->clnt;
  
  	req = p9_client_rpc(clnt, P9_TSYMLINK, "dssg", dfid->fid, name, symtgt,
  			gid);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Q", qid);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto free_and_error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RSYMLINK qid %x.%llx.%x\n",
  			qid->type, (unsigned long long)qid->path, qid->version);
  
  free_and_error:
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_symlink);
  
  int p9_client_link(struct p9_fid *dfid, struct p9_fid *oldfid, const char *newname)
  {
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	p9_debug(P9_DEBUG_9P, ">>> TLINK dfid %d oldfid %d newname %s\n",
  			dfid->fid, oldfid->fid, newname);
  	clnt = dfid->clnt;
  	req = p9_client_rpc(clnt, P9_TLINK, "dds", dfid->fid, oldfid->fid,
  			newname);
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	p9_debug(P9_DEBUG_9P, "<<< RLINK\n");
  	p9_tag_remove(clnt, req);
  	return 0;
  }
  EXPORT_SYMBOL(p9_client_link);
  
  int p9_client_fsync(struct p9_fid *fid, int datasync)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	p9_debug(P9_DEBUG_9P, ">>> TFSYNC fid %d datasync:%d\n",
  			fid->fid, datasync);
  	err = 0;
  	clnt = fid->clnt;
  
  	req = p9_client_rpc(clnt, P9_TFSYNC, "dd", fid->fid, datasync);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RFSYNC fid %d\n", fid->fid);
  
  	p9_tag_remove(clnt, req);
  
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_fsync);
  
  int p9_client_clunk(struct p9_fid *fid)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  	int retries = 0;
  
  	if (!fid) {
  		pr_warn("%s (%d): Trying to clunk with NULL fid\n",
  			__func__, task_pid_nr(current));
  		dump_stack();
  		return 0;
  	}
  
  again:
  	p9_debug(P9_DEBUG_9P, ">>> TCLUNK fid %d (try %d)\n", fid->fid,
  								retries);
  	err = 0;
  	clnt = fid->clnt;
  
  	req = p9_client_rpc(clnt, P9_TCLUNK, "d", fid->fid);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RCLUNK fid %d\n", fid->fid);
  
  	p9_tag_remove(clnt, req);
  error:
  	/*
  	 * Fid is not valid even after a failed clunk
  	 * If interrupted, retry once then give up and
  	 * leak fid until umount.
  	 */
  	if (err == -ERESTARTSYS) {
  		if (retries++ == 0)
  			goto again;
  	} else
  		p9_fid_destroy(fid);
  	return err;
  }
  EXPORT_SYMBOL(p9_client_clunk);
  
  int p9_client_remove(struct p9_fid *fid)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	p9_debug(P9_DEBUG_9P, ">>> TREMOVE fid %d\n", fid->fid);
  	err = 0;
  	clnt = fid->clnt;
  
  	req = p9_client_rpc(clnt, P9_TREMOVE, "d", fid->fid);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RREMOVE fid %d\n", fid->fid);
  
  	p9_tag_remove(clnt, req);
  error:
  	if (err == -ERESTARTSYS)
  		p9_client_clunk(fid);
  	else
  		p9_fid_destroy(fid);
  	return err;
  }
  EXPORT_SYMBOL(p9_client_remove);
  
  int p9_client_unlinkat(struct p9_fid *dfid, const char *name, int flags)
  {
  	int err = 0;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	p9_debug(P9_DEBUG_9P, ">>> TUNLINKAT fid %d %s %d\n",
  		   dfid->fid, name, flags);
  
  	clnt = dfid->clnt;
  	req = p9_client_rpc(clnt, P9_TUNLINKAT, "dsd", dfid->fid, name, flags);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RUNLINKAT fid %d %s\n", dfid->fid, name);
  
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_unlinkat);
  
  int
  p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err)
  {
  	struct p9_client *clnt = fid->clnt;
  	struct p9_req_t *req;
  	int total = 0;
  	*err = 0;
  
  	p9_debug(P9_DEBUG_9P, ">>> TREAD fid %d offset %llu %d\n",
  		   fid->fid, (unsigned long long) offset, (int)iov_iter_count(to));
  
  	while (iov_iter_count(to)) {
  		int count = iov_iter_count(to);
  		int rsize, non_zc = 0;
  		char *dataptr;
  
  		rsize = fid->iounit;
  		if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
  			rsize = clnt->msize - P9_IOHDRSZ;
  
  		if (count < rsize)
  			rsize = count;
  
  		/* Don't bother zerocopy for small IO (< 1024) */
  		if (clnt->trans_mod->zc_request && rsize > 1024) {
  			/*
  			 * response header len is 11
  			 * PDU Header(7) + IO Size (4)
  			 */
  			req = p9_client_zc_rpc(clnt, P9_TREAD, to, NULL, rsize,
  					       0, 11, "dqd", fid->fid,
  					       offset, rsize);
  		} else {
  			non_zc = 1;
  			req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
  					    rsize);
  		}
  		if (IS_ERR(req)) {
  			*err = PTR_ERR(req);
  			break;
  		}
  
  		*err = p9pdu_readf(&req->rc, clnt->proto_version,
  				   "D", &count, &dataptr);
  		if (*err) {
  			trace_9p_protocol_dump(clnt, &req->rc);
  			p9_tag_remove(clnt, req);
  			break;
  		}
  		if (rsize < count) {
  			pr_err("bogus RREAD count (%d > %d)\n", count, rsize);
  			count = rsize;
  		}
  
  		p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
  		if (!count) {
  			p9_tag_remove(clnt, req);
  			break;
  		}
  
  		if (non_zc) {
  			int n = copy_to_iter(dataptr, count, to);
  			total += n;
  			offset += n;
  			if (n != count) {
  				*err = -EFAULT;
  				p9_tag_remove(clnt, req);
  				break;
  			}
  		} else {
  			iov_iter_advance(to, count);
  			total += count;
  			offset += count;
  		}
  		p9_tag_remove(clnt, req);
  	}
  	return total;
  }
  EXPORT_SYMBOL(p9_client_read);
  
  int
  p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
  {
  	struct p9_client *clnt = fid->clnt;
  	struct p9_req_t *req;
  	int total = 0;
  	*err = 0;
  
  	p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %zd\n",
  				fid->fid, (unsigned long long) offset,
  				iov_iter_count(from));
  
  	while (iov_iter_count(from)) {
  		int count = iov_iter_count(from);
  		int rsize = fid->iounit;
  		if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
  			rsize = clnt->msize - P9_IOHDRSZ;
  
  		if (count < rsize)
  			rsize = count;
  
  		/* Don't bother zerocopy for small IO (< 1024) */
  		if (clnt->trans_mod->zc_request && rsize > 1024) {
  			req = p9_client_zc_rpc(clnt, P9_TWRITE, NULL, from, 0,
  					       rsize, P9_ZC_HDR_SZ, "dqd",
  					       fid->fid, offset, rsize);
  		} else {
  			req = p9_client_rpc(clnt, P9_TWRITE, "dqV", fid->fid,
  						    offset, rsize, from);
  		}
  		if (IS_ERR(req)) {
  			*err = PTR_ERR(req);
  			break;
  		}
  
  		*err = p9pdu_readf(&req->rc, clnt->proto_version, "d", &count);
  		if (*err) {
  			trace_9p_protocol_dump(clnt, &req->rc);
  			p9_tag_remove(clnt, req);
  			break;
  		}
  		if (rsize < count) {
  			pr_err("bogus RWRITE count (%d > %d)\n", count, rsize);
  			count = rsize;
  		}
  
  		p9_debug(P9_DEBUG_9P, "<<< RWRITE count %d\n", count);
  
  		p9_tag_remove(clnt, req);
  		iov_iter_advance(from, count);
  		total += count;
  		offset += count;
  	}
  	return total;
  }
  EXPORT_SYMBOL(p9_client_write);
  
  struct p9_wstat *p9_client_stat(struct p9_fid *fid)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_wstat *ret = kmalloc(sizeof(struct p9_wstat), GFP_KERNEL);
  	struct p9_req_t *req;
  	u16 ignored;
  
  	p9_debug(P9_DEBUG_9P, ">>> TSTAT fid %d\n", fid->fid);
  
  	if (!ret)
  		return ERR_PTR(-ENOMEM);
  
  	err = 0;
  	clnt = fid->clnt;
  
  	req = p9_client_rpc(clnt, P9_TSTAT, "d", fid->fid);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "wS", &ignored, ret);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		p9_tag_remove(clnt, req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P,
  		"<<< RSTAT sz=%x type=%x dev=%x qid=%x.%llx.%x\n"
  		"<<<    mode=%8.8x atime=%8.8x mtime=%8.8x length=%llx\n"
  		"<<<    name=%s uid=%s gid=%s muid=%s extension=(%s)\n"
  		"<<<    uid=%d gid=%d n_muid=%d\n",
  		ret->size, ret->type, ret->dev, ret->qid.type,
  		(unsigned long long)ret->qid.path, ret->qid.version, ret->mode,
  		ret->atime, ret->mtime, (unsigned long long)ret->length,
  		ret->name, ret->uid, ret->gid, ret->muid, ret->extension,
  		from_kuid(&init_user_ns, ret->n_uid),
  		from_kgid(&init_user_ns, ret->n_gid),
  		from_kuid(&init_user_ns, ret->n_muid));
  
  	p9_tag_remove(clnt, req);
  	return ret;
  
  error:
  	kfree(ret);
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(p9_client_stat);
  
  struct p9_stat_dotl *p9_client_getattr_dotl(struct p9_fid *fid,
  							u64 request_mask)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_stat_dotl *ret = kmalloc(sizeof(struct p9_stat_dotl),
  								GFP_KERNEL);
  	struct p9_req_t *req;
  
  	p9_debug(P9_DEBUG_9P, ">>> TGETATTR fid %d, request_mask %lld\n",
  							fid->fid, request_mask);
  
  	if (!ret)
  		return ERR_PTR(-ENOMEM);
  
  	err = 0;
  	clnt = fid->clnt;
  
  	req = p9_client_rpc(clnt, P9_TGETATTR, "dq", fid->fid, request_mask);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "A", ret);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		p9_tag_remove(clnt, req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P,
  		"<<< RGETATTR st_result_mask=%lld\n"
  		"<<< qid=%x.%llx.%x\n"
  		"<<< st_mode=%8.8x st_nlink=%llu\n"
  		"<<< st_uid=%d st_gid=%d\n"
  		"<<< st_rdev=%llx st_size=%llx st_blksize=%llu st_blocks=%llu\n"
  		"<<< st_atime_sec=%lld st_atime_nsec=%lld\n"
  		"<<< st_mtime_sec=%lld st_mtime_nsec=%lld\n"
  		"<<< st_ctime_sec=%lld st_ctime_nsec=%lld\n"
  		"<<< st_btime_sec=%lld st_btime_nsec=%lld\n"
  		"<<< st_gen=%lld st_data_version=%lld\n",
  		ret->st_result_mask, ret->qid.type, ret->qid.path,
  		ret->qid.version, ret->st_mode, ret->st_nlink,
  		from_kuid(&init_user_ns, ret->st_uid),
  		from_kgid(&init_user_ns, ret->st_gid),
  		ret->st_rdev, ret->st_size, ret->st_blksize,
  		ret->st_blocks, ret->st_atime_sec, ret->st_atime_nsec,
  		ret->st_mtime_sec, ret->st_mtime_nsec, ret->st_ctime_sec,
  		ret->st_ctime_nsec, ret->st_btime_sec, ret->st_btime_nsec,
  		ret->st_gen, ret->st_data_version);
  
  	p9_tag_remove(clnt, req);
  	return ret;
  
  error:
  	kfree(ret);
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(p9_client_getattr_dotl);
  
  static int p9_client_statsize(struct p9_wstat *wst, int proto_version)
  {
  	int ret;
  
  	/* NOTE: size shouldn't include its own length */
  	/* size[2] type[2] dev[4] qid[13] */
  	/* mode[4] atime[4] mtime[4] length[8]*/
  	/* name[s] uid[s] gid[s] muid[s] */
  	ret = 2+4+13+4+4+4+8+2+2+2+2;
  
  	if (wst->name)
  		ret += strlen(wst->name);
  	if (wst->uid)
  		ret += strlen(wst->uid);
  	if (wst->gid)
  		ret += strlen(wst->gid);
  	if (wst->muid)
  		ret += strlen(wst->muid);
  
  	if ((proto_version == p9_proto_2000u) ||
  		(proto_version == p9_proto_2000L)) {
  		ret += 2+4+4+4;	/* extension[s] n_uid[4] n_gid[4] n_muid[4] */
  		if (wst->extension)
  			ret += strlen(wst->extension);
  	}
  
  	return ret;
  }
  
  int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	err = 0;
  	clnt = fid->clnt;
  	wst->size = p9_client_statsize(wst, clnt->proto_version);
  	p9_debug(P9_DEBUG_9P, ">>> TWSTAT fid %d\n", fid->fid);
  	p9_debug(P9_DEBUG_9P,
  		"     sz=%x type=%x dev=%x qid=%x.%llx.%x\n"
  		"     mode=%8.8x atime=%8.8x mtime=%8.8x length=%llx\n"
  		"     name=%s uid=%s gid=%s muid=%s extension=(%s)\n"
  		"     uid=%d gid=%d n_muid=%d\n",
  		wst->size, wst->type, wst->dev, wst->qid.type,
  		(unsigned long long)wst->qid.path, wst->qid.version, wst->mode,
  		wst->atime, wst->mtime, (unsigned long long)wst->length,
  		wst->name, wst->uid, wst->gid, wst->muid, wst->extension,
  		from_kuid(&init_user_ns, wst->n_uid),
  		from_kgid(&init_user_ns, wst->n_gid),
  		from_kuid(&init_user_ns, wst->n_muid));
  
  	req = p9_client_rpc(clnt, P9_TWSTAT, "dwS", fid->fid, wst->size+2, wst);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RWSTAT fid %d\n", fid->fid);
  
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_wstat);
  
  int p9_client_setattr(struct p9_fid *fid, struct p9_iattr_dotl *p9attr)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	err = 0;
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> TSETATTR fid %d\n", fid->fid);
  	p9_debug(P9_DEBUG_9P,
  		"    valid=%x mode=%x uid=%d gid=%d size=%lld\n"
  		"    atime_sec=%lld atime_nsec=%lld\n"
  		"    mtime_sec=%lld mtime_nsec=%lld\n",
  		p9attr->valid, p9attr->mode,
  		from_kuid(&init_user_ns, p9attr->uid),
  		from_kgid(&init_user_ns, p9attr->gid),
  		p9attr->size, p9attr->atime_sec, p9attr->atime_nsec,
  		p9attr->mtime_sec, p9attr->mtime_nsec);
  
  	req = p9_client_rpc(clnt, P9_TSETATTR, "dI", fid->fid, p9attr);
  
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RSETATTR fid %d\n", fid->fid);
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_setattr);
  
  int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	err = 0;
  	clnt = fid->clnt;
  
  	p9_debug(P9_DEBUG_9P, ">>> TSTATFS fid %d\n", fid->fid);
  
  	req = p9_client_rpc(clnt, P9_TSTATFS, "d", fid->fid);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "ddqqqqqqd", &sb->type,
  			  &sb->bsize, &sb->blocks, &sb->bfree, &sb->bavail,
  			  &sb->files, &sb->ffree, &sb->fsid, &sb->namelen);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		p9_tag_remove(clnt, req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RSTATFS fid %d type 0x%lx bsize %ld "
  		"blocks %llu bfree %llu bavail %llu files %llu ffree %llu "
  		"fsid %llu namelen %ld\n",
  		fid->fid, (long unsigned int)sb->type, (long int)sb->bsize,
  		sb->blocks, sb->bfree, sb->bavail, sb->files,  sb->ffree,
  		sb->fsid, (long int)sb->namelen);
  
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_statfs);
  
  int p9_client_rename(struct p9_fid *fid,
  		     struct p9_fid *newdirfid, const char *name)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	err = 0;
  	clnt = fid->clnt;
  
  	p9_debug(P9_DEBUG_9P, ">>> TRENAME fid %d newdirfid %d name %s\n",
  			fid->fid, newdirfid->fid, name);
  
  	req = p9_client_rpc(clnt, P9_TRENAME, "dds", fid->fid,
  			newdirfid->fid, name);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RRENAME fid %d\n", fid->fid);
  
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_rename);
  
  int p9_client_renameat(struct p9_fid *olddirfid, const char *old_name,
  		       struct p9_fid *newdirfid, const char *new_name)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	err = 0;
  	clnt = olddirfid->clnt;
  
  	p9_debug(P9_DEBUG_9P, ">>> TRENAMEAT olddirfid %d old name %s"
  		   " newdirfid %d new name %s\n", olddirfid->fid, old_name,
  		   newdirfid->fid, new_name);
  
  	req = p9_client_rpc(clnt, P9_TRENAMEAT, "dsds", olddirfid->fid,
  			    old_name, newdirfid->fid, new_name);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RRENAMEAT newdirfid %d new name %s\n",
  		   newdirfid->fid, new_name);
  
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_renameat);
  
  /*
   * An xattrwalk without @attr_name gives the fid for the lisxattr namespace
   */
  struct p9_fid *p9_client_xattrwalk(struct p9_fid *file_fid,
  				const char *attr_name, u64 *attr_size)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  	struct p9_fid *attr_fid;
  
  	err = 0;
  	clnt = file_fid->clnt;
  	attr_fid = p9_fid_create(clnt);
  	if (!attr_fid) {
  		err = -ENOMEM;
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P,
  		">>> TXATTRWALK file_fid %d, attr_fid %d name %s\n",
  		file_fid->fid, attr_fid->fid, attr_name);
  
  	req = p9_client_rpc(clnt, P9_TXATTRWALK, "dds",
  			file_fid->fid, attr_fid->fid, attr_name);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "q", attr_size);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		p9_tag_remove(clnt, req);
  		goto clunk_fid;
  	}
  	p9_tag_remove(clnt, req);
  	p9_debug(P9_DEBUG_9P, "<<<  RXATTRWALK fid %d size %llu\n",
  		attr_fid->fid, *attr_size);
  	return attr_fid;
  clunk_fid:
  	p9_client_clunk(attr_fid);
  	attr_fid = NULL;
  error:
  	if (attr_fid && (attr_fid != file_fid))
  		p9_fid_destroy(attr_fid);
  
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL_GPL(p9_client_xattrwalk);
  
  int p9_client_xattrcreate(struct p9_fid *fid, const char *name,
  			u64 attr_size, int flags)
  {
  	int err;
  	struct p9_req_t *req;
  	struct p9_client *clnt;
  
  	p9_debug(P9_DEBUG_9P,
  		">>> TXATTRCREATE fid %d name  %s size %lld flag %d\n",
  		fid->fid, name, (long long)attr_size, flags);
  	err = 0;
  	clnt = fid->clnt;
  	req = p9_client_rpc(clnt, P9_TXATTRCREATE, "dsqd",
  			fid->fid, name, attr_size, flags);
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RXATTRCREATE fid %d\n", fid->fid);
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL_GPL(p9_client_xattrcreate);
  
  int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset)
  {
  	int err, rsize, non_zc = 0;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  	char *dataptr;
  	struct kvec kv = {.iov_base = data, .iov_len = count};
  	struct iov_iter to;
  
  	iov_iter_kvec(&to, READ, &kv, 1, count);
  
  	p9_debug(P9_DEBUG_9P, ">>> TREADDIR fid %d offset %llu count %d\n",
  				fid->fid, (unsigned long long) offset, count);
  
  	err = 0;
  	clnt = fid->clnt;
  
  	rsize = fid->iounit;
  	if (!rsize || rsize > clnt->msize-P9_READDIRHDRSZ)
  		rsize = clnt->msize - P9_READDIRHDRSZ;
  
  	if (count < rsize)
  		rsize = count;
  
  	/* Don't bother zerocopy for small IO (< 1024) */
  	if (clnt->trans_mod->zc_request && rsize > 1024) {
  		/*
  		 * response header len is 11
  		 * PDU Header(7) + IO Size (4)
  		 */
  		req = p9_client_zc_rpc(clnt, P9_TREADDIR, &to, NULL, rsize, 0,
  				       11, "dqd", fid->fid, offset, rsize);
  	} else {
  		non_zc = 1;
  		req = p9_client_rpc(clnt, P9_TREADDIR, "dqd", fid->fid,
  				    offset, rsize);
  	}
  	if (IS_ERR(req)) {
  		err = PTR_ERR(req);
  		goto error;
  	}
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "D", &count, &dataptr);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto free_and_error;
  	}
  	if (rsize < count) {
  		pr_err("bogus RREADDIR count (%d > %d)\n", count, rsize);
  		count = rsize;
  	}
  
  	p9_debug(P9_DEBUG_9P, "<<< RREADDIR count %d\n", count);
  
  	if (non_zc)
  		memmove(data, dataptr, count);
  
  	p9_tag_remove(clnt, req);
  	return count;
  
  free_and_error:
  	p9_tag_remove(clnt, req);
  error:
  	return err;
  }
  EXPORT_SYMBOL(p9_client_readdir);
  
  int p9_client_mknod_dotl(struct p9_fid *fid, const char *name, int mode,
  			dev_t rdev, kgid_t gid, struct p9_qid *qid)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	err = 0;
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> TMKNOD fid %d name %s mode %d major %d "
  		"minor %d\n", fid->fid, name, mode, MAJOR(rdev), MINOR(rdev));
  	req = p9_client_rpc(clnt, P9_TMKNOD, "dsdddg", fid->fid, name, mode,
  		MAJOR(rdev), MINOR(rdev), gid);
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Q", qid);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RMKNOD qid %x.%llx.%x\n", qid->type,
  				(unsigned long long)qid->path, qid->version);
  
  error:
  	p9_tag_remove(clnt, req);
  	return err;
  
  }
  EXPORT_SYMBOL(p9_client_mknod_dotl);
  
  int p9_client_mkdir_dotl(struct p9_fid *fid, const char *name, int mode,
  				kgid_t gid, struct p9_qid *qid)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	err = 0;
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> TMKDIR fid %d name %s mode %d gid %d\n",
  		 fid->fid, name, mode, from_kgid(&init_user_ns, gid));
  	req = p9_client_rpc(clnt, P9_TMKDIR, "dsdg", fid->fid, name, mode,
  		gid);
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "Q", qid);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RMKDIR qid %x.%llx.%x\n", qid->type,
  				(unsigned long long)qid->path, qid->version);
  
  error:
  	p9_tag_remove(clnt, req);
  	return err;
  
  }
  EXPORT_SYMBOL(p9_client_mkdir_dotl);
  
  int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	err = 0;
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> TLOCK fid %d type %i flags %d "
  			"start %lld length %lld proc_id %d client_id %s\n",
  			fid->fid, flock->type, flock->flags, flock->start,
  			flock->length, flock->proc_id, flock->client_id);
  
  	req = p9_client_rpc(clnt, P9_TLOCK, "dbdqqds", fid->fid, flock->type,
  				flock->flags, flock->start, flock->length,
  					flock->proc_id, flock->client_id);
  
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "b", status);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RLOCK status %i\n", *status);
  error:
  	p9_tag_remove(clnt, req);
  	return err;
  
  }
  EXPORT_SYMBOL(p9_client_lock_dotl);
  
  int p9_client_getlock_dotl(struct p9_fid *fid, struct p9_getlock *glock)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	err = 0;
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> TGETLOCK fid %d, type %i start %lld "
  		"length %lld proc_id %d client_id %s\n", fid->fid, glock->type,
  		glock->start, glock->length, glock->proc_id, glock->client_id);
  
  	req = p9_client_rpc(clnt, P9_TGETLOCK, "dbqqds", fid->fid,  glock->type,
  		glock->start, glock->length, glock->proc_id, glock->client_id);
  
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "bqqds", &glock->type,
  			  &glock->start, &glock->length, &glock->proc_id,
  			  &glock->client_id);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RGETLOCK type %i start %lld length %lld "
  		"proc_id %d client_id %s\n", glock->type, glock->start,
  		glock->length, glock->proc_id, glock->client_id);
  error:
  	p9_tag_remove(clnt, req);
  	return err;
  }
  EXPORT_SYMBOL(p9_client_getlock_dotl);
  
  int p9_client_readlink(struct p9_fid *fid, char **target)
  {
  	int err;
  	struct p9_client *clnt;
  	struct p9_req_t *req;
  
  	err = 0;
  	clnt = fid->clnt;
  	p9_debug(P9_DEBUG_9P, ">>> TREADLINK fid %d\n", fid->fid);
  
  	req = p9_client_rpc(clnt, P9_TREADLINK, "d", fid->fid);
  	if (IS_ERR(req))
  		return PTR_ERR(req);
  
  	err = p9pdu_readf(&req->rc, clnt->proto_version, "s", target);
  	if (err) {
  		trace_9p_protocol_dump(clnt, &req->rc);
  		goto error;
  	}
  	p9_debug(P9_DEBUG_9P, "<<< RREADLINK target %s\n", *target);
  error:
  	p9_tag_remove(clnt, req);
  	return err;
  }
  EXPORT_SYMBOL(p9_client_readlink);
  
  int __init p9_client_init(void)
  {
  	p9_req_cache = KMEM_CACHE(p9_req_t, SLAB_TYPESAFE_BY_RCU);
  	return p9_req_cache ? 0 : -ENOMEM;
  }
  
  void __exit p9_client_exit(void)
  {
  	kmem_cache_destroy(p9_req_cache);
  }
  