client.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 9P Client
 *
 *  Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
 */

#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 <linux/netfs.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>

/* DEFAULT MSIZE = 32 pages worth of payload + P9_HDRSZ +
 * room for write (16 extra) or read (11 extra) operands.
 */

#define DEFAULT_MSIZE ((128 * 1024) + P9_IOHDRSZ)

/* 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 != DEFAULT_MSIZE)
		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_opts - 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 = DEFAULT_MSIZE;

	if (!opts)
		return 0;

	tmp_options = kstrdup(opts, GFP_KERNEL);
	if (!tmp_options)
		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) {
				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;
	fc->id = 0;
	fc->tag = P9_NOTAG;
	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_tag_alloc - Allocate a new request.
 * @c: Client session.
 * @type: Transaction type.
 * @t_size: Buffer size for holding this request
 * (automatic calculation by format template if 0).
 * @r_size: Buffer size for holding server's reply on this request
 * (automatic calculation by format template if 0).
 * @fmt: Format template for assembling 9p request message
 * (see p9pdu_vwritef).
 * @ap: Variable arguments to be fed to passed format template
 * (see p9pdu_vwritef).
 *
 * Context: Process context.
 * Return: Pointer to new request.
 */
static struct p9_req_t *
p9_tag_alloc(struct p9_client *c, int8_t type, uint t_size, uint r_size,
	      const char *fmt, va_list ap)
{
	struct p9_req_t *req = kmem_cache_alloc(p9_req_cache, GFP_NOFS);
	int alloc_tsize;
	int alloc_rsize;
	int tag;
	va_list apc;

	va_copy(apc, ap);
	alloc_tsize = min_t(size_t, c->msize,
			    t_size ?: p9_msg_buf_size(c, type, fmt, apc));
	va_end(apc);

	alloc_rsize = min_t(size_t, c->msize,
			    r_size ?: p9_msg_buf_size(c, type + 1, fmt, ap));

	if (!req)
		return ERR_PTR(-ENOMEM);

	if (p9_fcall_init(c, &req->tc, alloc_tsize))
		goto free_req;
	if (p9_fcall_init(c, &req->rc, alloc_rsize))
		goto free;

	p9pdu_reset(&req->tc);
	p9pdu_reset(&req->rc);
	req->t_err = 0;
	req->status = REQ_STATUS_ALLOC;
	/* refcount needs to be set to 0 before inserting into the idr
	 * so p9_tag_lookup does not accept a request that is not fully
	 * initialized. refcount_set to 2 below will mark request ready.
	 */
	refcount_set(&req->refcount, 0);
	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_req_put 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, 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(c, 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 void 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, "freeing 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);
}

int p9_req_put(struct p9_client *c, struct p9_req_t *r)
{
	if (refcount_dec_and_test(&r->refcount)) {
		p9_tag_remove(c, r);

		p9_fcall_fini(&r->tc);
		p9_fcall_fini(&r->rc);
		kmem_cache_free(p9_req_cache, r);
		return 1;
	}
	return 0;
}
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_req_put(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
 * @status: request status, one of REQ_STATUS_*
 *
 */
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();
	WRITE_ONCE(req->status, status);

	wake_up(&req->wq);
	p9_debug(P9_DEBUG_MUX, "wakeup: %d\n", req->tc.tag);
	p9_req_put(c, 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)
{
	s8 r_type;
	s16 r_tag;
	s32 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)
{
	s8 type;
	int err;
	int ecode;

	err = p9_parse_header(&req->rc, NULL, &type, NULL, 0);
	if (req->rc.size > req->rc.capacity && !req->rc.zc) {
		pr_err("requested packet size too big: %d does not fit %zu (type=%d)\n",
		       req->rc.size, req->rc.capacity, req->rc.id);
		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 = NULL;

		err = p9pdu_readf(&req->rc, c->proto_version, "s?d",
				  &ename, &ecode);
		if (err) {
			kfree(ename);
			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);
		if (err)
			goto out_err;
		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;
	s16 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 (READ_ONCE(oldreq->status) == REQ_STATUS_SENT) {
		if (c->trans_mod->cancelled)
			c->trans_mod->cancelled(c, oldreq);
	}

	p9_req_put(c, req);
	return 0;
}

static struct p9_req_t *p9_client_prepare_req(struct p9_client *c,
					      int8_t type, uint t_size, uint r_size,
					      const char *fmt, va_list ap)
{
	int err;
	struct p9_req_t *req;
	va_list apc;

	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);

	va_copy(apc, ap);
	req = p9_tag_alloc(c, type, t_size, r_size, fmt, apc);
	va_end(apc);
	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_req_put(c, req);
	/* We have to put also the 2nd reference as it won't be used */
	p9_req_put(c, 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_req_put)
 */

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;
	/* Passing zero for tsize/rsize to p9_client_prepare_req() tells it to
	 * auto determine an appropriate (small) request/response size
	 * according to actual message data being sent. Currently RDMA
	 * transport is excluded from this response message size optimization,
	 * as it would not cope with it, due to its pooled response buffers
	 * (using an optimized request size for RDMA as well though).
	 */
	const uint tsize = 0;
	const uint rsize = c->trans_mod->pooled_rbuffers ? c->msize : 0;

	va_start(ap, fmt);
	req = p9_client_prepare_req(c, type, tsize, rsize, fmt, ap);
	va_end(ap);
	if (IS_ERR(req))
		return req;

	req->tc.zc = false;
	req->rc.zc = false;

	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(c, req);
		if (err != -ERESTARTSYS && err != -EFAULT)
			c->status = Disconnected;
		goto recalc_sigpending;
	}
again:
	/* Wait for the response */
	err = wait_event_killable(req->wq,
				  READ_ONCE(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 (READ_ONCE(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 (READ_ONCE(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_req_put(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
 * @in_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_req_put)
 */
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, P9_ZC_HDR_SZ, fmt, ap);
	va_end(ap);
	if (IS_ERR(req))
		return req;

	req->tc.zc = true;
	req->rc.zc = true;

	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 (READ_ONCE(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 (READ_ONCE(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_req_put(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 = kzalloc(sizeof(*fid), GFP_KERNEL);
	if (!fid)
		return NULL;

	fid->mode = -1;
	fid->uid = current_fsuid();
	fid->clnt = clnt;
	refcount_set(&fid->count, 1);

	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) {
		trace_9p_fid_ref(fid, P9_FID_REF_CREATE);
		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);
	trace_9p_fid_ref(fid, P9_FID_REF_DESTROY);
	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);
}

/* We also need to export tracepoint symbols for tracepoint_enabled() */
EXPORT_TRACEPOINT_SYMBOL(9p_fid_ref);

void do_trace_9p_fid_get(struct p9_fid *fid)
{
	trace_9p_fid_ref(fid, P9_FID_REF_GET);
}
EXPORT_SYMBOL(do_trace_9p_fid_get);

void do_trace_9p_fid_put(struct p9_fid *fid)
{
	trace_9p_fid_ref(fid, P9_FID_REF_PUT);
}
EXPORT_SYMBOL(do_trace_9p_fid_put);

static int p9_client_version(struct p9_client *c)
{
	int err;
	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_req_put(c, req);

	return err;
}

struct p9_client *p9_client_create(const char *dev_name, char *options)
{
	int err;
	static atomic_t seqno = ATOMIC_INIT(0);
	struct p9_client *clnt;
	char *client_id;
	char *cache_name;

	clnt = kmalloc(sizeof(*clnt), 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);