Merge branch 'devel-stable' into devel

[deliverable/linux.git] / net / 9p / client.c

/*
 * net/9p/clnt.c
 *
 * 9P Client
 *
 *  Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <net/9p/9p.h>
#include <linux/parser.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include "protocol.h"

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

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

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

static struct p9_req_t *
p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...);

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

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

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

        if (!opts)
                return 0;

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

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

        kfree(options);
        return ret;
}

/**
 * p9_tag_alloc - lookup/allocate a request by tag
 * @c: client session to lookup tag within
 * @tag: numeric id for transaction
 *
 * this is a simple array lookup, but will grow the
 * request_slots as necessary to accomodate transaction
 * ids which did not previously have a slot.
 *
 * this code relies on the client spinlock to manage locks, its
 * possible we should switch to something else, but I'd rather
 * stick with something low-overhead for the common case.
 *
 */

static struct p9_req_t *p9_tag_alloc(struct p9_client *c, u16 tag)
{
        unsigned long flags;
        int row, col;
        struct p9_req_t *req;

        /* This looks up the original request by tag so we know which
         * buffer to read the data into */
        tag++;

        if (tag >= c->max_tag) {
                spin_lock_irqsave(&c->lock, flags);
                /* check again since original check was outside of lock */
                while (tag >= c->max_tag) {
                        row = (tag / P9_ROW_MAXTAG);
                        c->reqs[row] = kcalloc(P9_ROW_MAXTAG,
                                        sizeof(struct p9_req_t), GFP_ATOMIC);

                        if (!c->reqs[row]) {
                                printk(KERN_ERR "Couldn't grow tag array\n");
                                spin_unlock_irqrestore(&c->lock, flags);
                                return ERR_PTR(-ENOMEM);
                        }
                        for (col = 0; col < P9_ROW_MAXTAG; col++) {
                                c->reqs[row][col].status = REQ_STATUS_IDLE;
                                c->reqs[row][col].tc = NULL;
                        }
                        c->max_tag += P9_ROW_MAXTAG;
                }
                spin_unlock_irqrestore(&c->lock, flags);
        }
        row = tag / P9_ROW_MAXTAG;
        col = tag % P9_ROW_MAXTAG;

        req = &c->reqs[row][col];
        if (!req->tc) {
                req->wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
                if (!req->wq) {
                        printk(KERN_ERR "Couldn't grow tag array\n");
                        return ERR_PTR(-ENOMEM);
                }
                init_waitqueue_head(req->wq);
                req->tc = kmalloc(sizeof(struct p9_fcall)+c->msize,
                                                                GFP_KERNEL);
                req->rc = kmalloc(sizeof(struct p9_fcall)+c->msize,
                                                                GFP_KERNEL);
                if ((!req->tc) || (!req->rc)) {
                        printk(KERN_ERR "Couldn't grow tag array\n");
                        kfree(req->tc);
                        kfree(req->rc);
                        kfree(req->wq);
                        req->tc = req->rc = NULL;
                        req->wq = NULL;
                        return ERR_PTR(-ENOMEM);
                }
                req->tc->sdata = (char *) req->tc + sizeof(struct p9_fcall);
                req->tc->capacity = c->msize;
                req->rc->sdata = (char *) req->rc + sizeof(struct p9_fcall);
                req->rc->capacity = c->msize;
        }

        p9pdu_reset(req->tc);
        p9pdu_reset(req->rc);

        req->tc->tag = tag-1;
        req->status = REQ_STATUS_ALLOC;

        return &c->reqs[row][col];
}

/**
 * p9_tag_lookup - lookup a request by tag
 * @c: client session to lookup tag within
 * @tag: numeric id for transaction
 *
 */

struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag)
{
        int row, col;

        /* This looks up the original request by tag so we know which
         * buffer to read the data into */
        tag++;

        BUG_ON(tag >= c->max_tag);

        row = tag / P9_ROW_MAXTAG;
        col = tag % P9_ROW_MAXTAG;

        return &c->reqs[row][col];
}
EXPORT_SYMBOL(p9_tag_lookup);

/**
 * p9_tag_init - setup tags structure and contents
 * @tags: tags structure from the client struct
 *
 * This initializes the tags structure for each client instance.
 *
 */

static int p9_tag_init(struct p9_client *c)
{
        int err = 0;

        c->tagpool = p9_idpool_create();
        if (IS_ERR(c->tagpool)) {
                err = PTR_ERR(c->tagpool);
                c->tagpool = NULL;
                goto error;
        }

        p9_idpool_get(c->tagpool); /* reserve tag 0 */

        c->max_tag = 0;
error:
        return err;
}

/**
 * p9_tag_cleanup - cleans up tags structure and reclaims resources
 * @tags: tags structure from the client struct
 *
 * This frees resources associated with the tags structure
 *
 */
static void p9_tag_cleanup(struct p9_client *c)
{
        int row, col;

        /* check to insure all requests are idle */
        for (row = 0; row < (c->max_tag/P9_ROW_MAXTAG); row++) {
                for (col = 0; col < P9_ROW_MAXTAG; col++) {
                        if (c->reqs[row][col].status != REQ_STATUS_IDLE) {
                                P9_DPRINTK(P9_DEBUG_MUX,
                                  "Attempting to cleanup non-free tag %d,%d\n",
                                  row, col);
                                /* TODO: delay execution of cleanup */
                                return;
                        }
                }
        }

        if (c->tagpool)
                p9_idpool_destroy(c->tagpool);

        /* free requests associated with tags */
        for (row = 0; row < (c->max_tag/P9_ROW_MAXTAG); row++) {
                for (col = 0; col < P9_ROW_MAXTAG; col++) {
                        kfree(c->reqs[row][col].wq);
                        kfree(c->reqs[row][col].tc);
                        kfree(c->reqs[row][col].rc);
                }
                kfree(c->reqs[row]);
        }
        c->max_tag = 0;
}

/**
 * p9_free_req - free a request and clean-up as necessary
 * c: client state
 * r: request to release
 *
 */

static void p9_free_req(struct p9_client *c, struct p9_req_t *r)
{
        int tag = r->tc->tag;
        P9_DPRINTK(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag);

        r->status = REQ_STATUS_IDLE;
        if (tag != P9_NOTAG && p9_idpool_check(tag, c->tagpool))
                p9_idpool_put(tag, c->tagpool);
}

/**
 * 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)
{
        P9_DPRINTK(P9_DEBUG_MUX, " tag %d\n", req->tc->tag);
        wake_up(req->wq);
        P9_DPRINTK(P9_DEBUG_MUX, "wakeup: %d\n", req->tc->tag);
}
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;
        if (pdu->size == 0)
                pdu->size = 7;

        err = p9pdu_readf(pdu, 0, "dbw", &r_size, &r_type, &r_tag);
        if (err)
                goto rewind_and_exit;

        pdu->size = r_size;
        pdu->id = r_type;
        pdu->tag = r_tag;

        P9_DPRINTK(P9_DEBUG_9P, "<<< size=%d type: %d tag: %d\n", pdu->size,
                                                        pdu->id, pdu->tag);

        if (type)
                *type = r_type;
        if (tag)
                *tag = r_tag;
        if (size)
                *size = r_size;


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;

        err = p9_parse_header(req->rc, NULL, &type, NULL, 0);
        if (err) {
                P9_DPRINTK(P9_DEBUG_ERROR, "couldn't parse header %d\n", err);
                return err;
        }

        if (type == P9_RERROR) {
                int ecode;
                char *ename;

                err = p9pdu_readf(req->rc, c->dotu, "s?d", &ename, &ecode);
                if (err) {
                        P9_DPRINTK(P9_DEBUG_ERROR, "couldn't parse error%d\n",
                                                                        err);
                        return err;
                }

                if (c->dotu)
                        err = -ecode;

                if (!err) {
                        err = p9_errstr2errno(ename, strlen(ename));

                        /* string match failed */
                        if (!err)
                                err = -ESERVERFAULT;
                }

                P9_DPRINTK(P9_DEBUG_9P, "<<< RERROR (%d) %s\n", -ecode, ename);

                kfree(ename);
        } else
                err = 0;

        return err;
}

/**
 * p9_client_flush - flush (cancel) a request
 * c: client state
 * req: request to cancel
 *
 * This sents a flush for a particular requests 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_DPRINTK(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. */
        spin_lock(&c->lock);
        if (oldreq->status == REQ_STATUS_FLSH)
                list_del(&oldreq->req_list);
        spin_unlock(&c->lock);

        p9_free_req(c, req);
        return 0;
}

/**
 * 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_free_req)
 */

static struct p9_req_t *
p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
{
        va_list ap;
        int tag, err;
        struct p9_req_t *req;
        unsigned long flags;
        int sigpending;

        P9_DPRINTK(P9_DEBUG_MUX, "client %p op %d\n", c, type);

        if (c->status != Connected)
                return ERR_PTR(-EIO);

        if (signal_pending(current)) {
                sigpending = 1;
                clear_thread_flag(TIF_SIGPENDING);
        } else
                sigpending = 0;

        tag = P9_NOTAG;
        if (type != P9_TVERSION) {
                tag = p9_idpool_get(c->tagpool);
                if (tag < 0)
                        return ERR_PTR(-ENOMEM);
        }

        req = p9_tag_alloc(c, tag);
        if (IS_ERR(req))
                return req;

        /* marshall the data */
        p9pdu_prepare(req->tc, tag, type);
        va_start(ap, fmt);
        err = p9pdu_vwritef(req->tc, c->dotu, fmt, ap);
        va_end(ap);
        p9pdu_finalize(req->tc);

        err = c->trans_mod->request(c, req);
        if (err < 0) {
                c->status = Disconnected;
                goto reterr;
        }

        P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d\n", req->wq, tag);
        err = wait_event_interruptible(*req->wq,
                                                req->status >= REQ_STATUS_RCVD);
        P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d returned %d\n",
                                                req->wq, tag, err);

        if (req->status == REQ_STATUS_ERROR) {
                P9_DPRINTK(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
                err = req->t_err;
        }

        if ((err == -ERESTARTSYS) && (c->status == Connected)) {
                P9_DPRINTK(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;
        }

        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);
        if (!err) {
                P9_DPRINTK(P9_DEBUG_MUX, "exit: client %p op %d\n", c, type);
                return req;
        }

reterr:
        P9_DPRINTK(P9_DEBUG_MUX, "exit: client %p op %d error: %d\n", c, type,
                                                                        err);
        p9_free_req(c, req);
        return ERR_PTR(err);
}

static struct p9_fid *p9_fid_create(struct p9_client *clnt)
{
        int ret;
        struct p9_fid *fid;
        unsigned long flags;

        P9_DPRINTK(P9_DEBUG_FID, "clnt %p\n", clnt);
        fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
        if (!fid)
                return ERR_PTR(-ENOMEM);

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

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

        spin_lock_irqsave(&clnt->lock, flags);
        list_add(&fid->flist, &clnt->fidlist);
        spin_unlock_irqrestore(&clnt->lock, flags);

        return fid;

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

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

        P9_DPRINTK(P9_DEBUG_FID, "fid %d\n", fid->fid);
        clnt = fid->clnt;
        p9_idpool_put(fid->fid, clnt->fidpool);
        spin_lock_irqsave(&clnt->lock, flags);
        list_del(&fid->flist);
        spin_unlock_irqrestore(&clnt->lock, flags);
        kfree(fid);
}

int p9_client_version(struct p9_client *c)
{
        int err = 0;
        struct p9_req_t *req;
        char *version;
        int msize;

        P9_DPRINTK(P9_DEBUG_9P, ">>> TVERSION msize %d extended %d\n",
                                                        c->msize, c->dotu);
        req = p9_client_rpc(c, P9_TVERSION, "ds", c->msize,
                                c->dotu ? "9P2000.u" : "9P2000");
        if (IS_ERR(req))
                return PTR_ERR(req);

        err = p9pdu_readf(req->rc, c->dotu, "ds", &msize, &version);
        if (err) {
                P9_DPRINTK(P9_DEBUG_9P, "version error %d\n", err);
                p9pdu_dump(1, req->rc);
                goto error;
        }

        P9_DPRINTK(P9_DEBUG_9P, "<<< RVERSION msize %d %s\n", msize, version);
        if (!memcmp(version, "9P2000.u", 8))
                c->dotu = 1;
        else if (!memcmp(version, "9P2000", 6))
                c->dotu = 0;
        else {
                err = -EREMOTEIO;
                goto error;
        }

        if (msize < c->msize)
                c->msize = msize;

error:
        kfree(version);
        p9_free_req(c, req);

        return err;
}
EXPORT_SYMBOL(p9_client_version);

struct p9_client *p9_client_create(const char *dev_name, char *options)
{
        int err;
        struct p9_client *clnt;

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

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

        p9_tag_init(clnt);

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

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

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

        P9_DPRINTK(P9_DEBUG_MUX, "clnt %p trans %p msize %d dotu %d\n",
                clnt, clnt->trans_mod, clnt->msize, clnt->dotu);

        err = clnt->trans_mod->create(clnt, dev_name, options);
        if (err)
                goto error;

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

        err = p9_client_version(clnt);
        if (err)
                goto error;

        return clnt;

error:
        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_MUX, "clnt %p\n", clnt);

        if (clnt->trans_mod)
                clnt->trans_mod->close(clnt);

        v9fs_put_trans(clnt->trans_mod);

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

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

        p9_tag_cleanup(clnt);

        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->status = Disconnected;
}
EXPORT_SYMBOL(p9_client_disconnect);

struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
        char *uname, u32 n_uname, char *aname)
{
        int err;
        struct p9_req_t *req;
        struct p9_fid *fid;
        struct p9_qid qid;

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

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

        req = p9_client_rpc(clnt, P9_TATTACH, "ddss?d", 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->dotu, "Q", &qid);
        if (err) {
                p9pdu_dump(1, req->rc);
                p9_free_req(clnt, req);
                goto error;
        }

        P9_DPRINTK(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_free_req(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_auth(struct p9_client *clnt, char *uname, u32 n_uname, char *aname)
{
        int err;
        struct p9_req_t *req;
        struct p9_qid qid;
        struct p9_fid *afid;

        P9_DPRINTK(P9_DEBUG_9P, ">>> TAUTH uname %s aname %s\n", uname, aname);
        err = 0;

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

        req = p9_client_rpc(clnt, P9_TAUTH, "dss?d",
                        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->dotu, "Q", &qid);
        if (err) {
                p9pdu_dump(1, req->rc);
                p9_free_req(clnt, req);
                goto error;
        }

        P9_DPRINTK(P9_DEBUG_9P, "<<< RAUTH qid %x.%llx.%x\n",
                                        qid.type,
                                        (unsigned long long)qid.path,
                                        qid.version);

        memmove(&afid->qid, &qid, sizeof(struct p9_qid));
        p9_free_req(clnt, req);
        return afid;

error:
        if (afid)
                p9_fid_destroy(afid);
        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_client *clnt;
        struct p9_fid *fid;
        struct p9_qid *wqids;
        struct p9_req_t *req;
        int16_t nwqids, count;

        err = 0;
        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;


        P9_DPRINTK(P9_DEBUG_9P, ">>> TWALK fids %d,%d nwname %d 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->dotu, "R", &nwqids, &wqids);
        if (err) {
                p9pdu_dump(1, req->rc);
                p9_free_req(clnt, req);
                goto clunk_fid;
        }
        p9_free_req(clnt, req);

        P9_DPRINTK(P9_DEBUG_9P, "<<< RWALK nwqid %d:\n", nwqids);

        if (nwqids != nwname) {
                err = -ENOENT;
                goto clunk_fid;
        }

        for (count = 0; count < nwqids; count++)
                P9_DPRINTK(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;

        return fid;

clunk_fid:
        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;

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

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

        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->dotu, "Qd", &qid, &iounit);
        if (err) {
                p9pdu_dump(1, req->rc);
                goto free_and_error;
        }

        P9_DPRINTK(P9_DEBUG_9P, "<<< ROPEN 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_free_req(clnt, req);
error:
        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_client *clnt;
        struct p9_req_t *req;
        struct p9_qid qid;
        int iounit;

        P9_DPRINTK(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->dotu, "Qd", &qid, &iounit);
        if (err) {
                p9pdu_dump(1, req->rc);
                goto free_and_error;
        }

        P9_DPRINTK(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_free_req(clnt, req);
error:
        return err;
}
EXPORT_SYMBOL(p9_client_fcreate);

int p9_client_clunk(struct p9_fid *fid)
{
        int err;
        struct p9_client *clnt;
        struct p9_req_t *req;

        P9_DPRINTK(P9_DEBUG_9P, ">>> TCLUNK fid %d\n", fid->fid);
        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_DPRINTK(P9_DEBUG_9P, "<<< RCLUNK fid %d\n", fid->fid);

        p9_free_req(clnt, req);
        p9_fid_destroy(fid);

error:
        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_DPRINTK(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_DPRINTK(P9_DEBUG_9P, "<<< RREMOVE fid %d\n", fid->fid);

        p9_free_req(clnt, req);
        p9_fid_destroy(fid);

error:
        return err;
}
EXPORT_SYMBOL(p9_client_remove);

int
p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
                                                                u32 count)
{
        int err, rsize, total;
        struct p9_client *clnt;
        struct p9_req_t *req;
        char *dataptr;

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

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

        if (count < rsize)
                rsize = count;

        req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset, rsize);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto error;
        }

        err = p9pdu_readf(req->rc, clnt->dotu, "D", &count, &dataptr);
        if (err) {
                p9pdu_dump(1, req->rc);
                goto free_and_error;
        }

        P9_DPRINTK(P9_DEBUG_9P, "<<< RREAD count %d\n", count);

        if (data) {
                memmove(data, dataptr, count);
        }

        if (udata) {
                err = copy_to_user(udata, dataptr, count);
                if (err) {
                        err = -EFAULT;
                        goto free_and_error;
                }
        }

        p9_free_req(clnt, req);
        return count;

free_and_error:
        p9_free_req(clnt, req);
error:
        return err;
}
EXPORT_SYMBOL(p9_client_read);

int
p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
                                                        u64 offset, u32 count)
{
        int err, rsize, total;
        struct p9_client *clnt;
        struct p9_req_t *req;

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

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

        if (count < rsize)
                rsize = count;
        if (data)
                req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid, offset,
                                                                rsize, data);
        else
                req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid, offset,
                                                                rsize, udata);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto error;
        }

        err = p9pdu_readf(req->rc, clnt->dotu, "d", &count);
        if (err) {
                p9pdu_dump(1, req->rc);
                goto free_and_error;
        }

        P9_DPRINTK(P9_DEBUG_9P, "<<< RWRITE count %d\n", count);

        p9_free_req(clnt, req);
        return count;

free_and_error:
        p9_free_req(clnt, req);
error:
        return err;
}
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_DPRINTK(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->dotu, "wS", &ignored, ret);
        if (err) {
                p9pdu_dump(1, req->rc);
                p9_free_req(clnt, req);
                goto error;
        }

        P9_DPRINTK(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,
                ret->n_uid, ret->n_gid, ret->n_muid);

        p9_free_req(clnt, req);
        return ret;

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

static int p9_client_statsize(struct p9_wstat *wst, int optional)
{
        int ret;

        /* 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+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 (optional) {
                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->dotu);
        P9_DPRINTK(P9_DEBUG_9P, ">>> TWSTAT fid %d\n", fid->fid);
        P9_DPRINTK(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,
                wst->n_uid, wst->n_gid, wst->n_muid);

        req = p9_client_rpc(clnt, P9_TWSTAT, "dwS", fid->fid, wst->size, wst);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto error;
        }

        P9_DPRINTK(P9_DEBUG_9P, "<<< RWSTAT fid %d\n", fid->fid);

        p9_free_req(clnt, req);
error:
        return err;
}
EXPORT_SYMBOL(p9_client_wstat);