linux/fs/9p/mux.c

476 lines
10 KiB
C

/*
* linux/fs/9p/mux.c
*
* Protocol Multiplexer
*
* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 2004 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 as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kthread.h>
#include <linux/idr.h>
#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "transport.h"
#include "conv.h"
#include "mux.h"
/**
* dprintcond - print condition of session info
* @v9ses: session info structure
* @req: RPC request structure
*
*/
static inline int
dprintcond(struct v9fs_session_info *v9ses, struct v9fs_rpcreq *req)
{
dprintk(DEBUG_MUX, "condition: %d, %p\n", v9ses->transport->status,
req->rcall);
return 0;
}
/**
* xread - force read of a certain number of bytes
* @v9ses: session info structure
* @ptr: pointer to buffer
* @sz: number of bytes to read
*
* Chuck Cranor CS-533 project1
*/
static int xread(struct v9fs_session_info *v9ses, void *ptr, unsigned long sz)
{
int rd = 0;
int ret = 0;
while (rd < sz) {
ret = v9ses->transport->read(v9ses->transport, ptr, sz - rd);
if (ret <= 0) {
dprintk(DEBUG_ERROR, "xread errno %d\n", ret);
return ret;
}
rd += ret;
ptr += ret;
}
return (rd);
}
/**
* read_message - read a full 9P2000 fcall packet
* @v9ses: session info structure
* @rcall: fcall structure to read into
* @rcalllen: size of fcall buffer
*
*/
static int
read_message(struct v9fs_session_info *v9ses,
struct v9fs_fcall *rcall, int rcalllen)
{
unsigned char buf[4];
void *data;
int size = 0;
int res = 0;
res = xread(v9ses, buf, sizeof(buf));
if (res < 0) {
dprintk(DEBUG_ERROR,
"Reading of count field failed returned: %d\n", res);
return res;
}
if (res < 4) {
dprintk(DEBUG_ERROR,
"Reading of count field failed returned: %d\n", res);
return -EIO;
}
size = buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
dprintk(DEBUG_MUX, "got a packet count: %d\n", size);
/* adjust for the four bytes of size */
size -= 4;
if (size > v9ses->maxdata) {
dprintk(DEBUG_ERROR, "packet too big: %d\n", size);
return -E2BIG;
}
data = kmalloc(size, GFP_KERNEL);
if (!data) {
eprintk(KERN_WARNING, "out of memory\n");
return -ENOMEM;
}
res = xread(v9ses, data, size);
if (res < size) {
dprintk(DEBUG_ERROR, "Reading of fcall failed returned: %d\n",
res);
kfree(data);
return res;
}
/* we now have an in-memory string that is the reply.
* deserialize it. There is very little to go wrong at this point
* save for v9fs_alloc errors.
*/
res = v9fs_deserialize_fcall(v9ses, size, data, v9ses->maxdata,
rcall, rcalllen);
kfree(data);
if (res < 0)
return res;
return 0;
}
/**
* v9fs_recv - receive an RPC response for a particular tag
* @v9ses: session info structure
* @req: RPC request structure
*
*/
static int v9fs_recv(struct v9fs_session_info *v9ses, struct v9fs_rpcreq *req)
{
int ret = 0;
dprintk(DEBUG_MUX, "waiting for response: %d\n", req->tcall->tag);
ret = wait_event_interruptible(v9ses->read_wait,
((v9ses->transport->status != Connected) ||
(req->rcall != 0) || (req->err < 0) ||
dprintcond(v9ses, req)));
dprintk(DEBUG_MUX, "got it: rcall %p\n", req->rcall);
spin_lock(&v9ses->muxlock);
list_del(&req->next);
spin_unlock(&v9ses->muxlock);
if (req->err < 0)
return req->err;
if (v9ses->transport->status == Disconnected)
return -ECONNRESET;
return ret;
}
/**
* v9fs_send - send a 9P request
* @v9ses: session info structure
* @req: RPC request to send
*
*/
static int v9fs_send(struct v9fs_session_info *v9ses, struct v9fs_rpcreq *req)
{
int ret = -1;
void *data = NULL;
struct v9fs_fcall *tcall = req->tcall;
data = kmalloc(v9ses->maxdata + V9FS_IOHDRSZ, GFP_KERNEL);
if (!data)
return -ENOMEM;
tcall->size = 0; /* enforce size recalculation */
ret =
v9fs_serialize_fcall(v9ses, tcall, data,
v9ses->maxdata + V9FS_IOHDRSZ);
if (ret < 0)
goto free_data;
spin_lock(&v9ses->muxlock);
list_add(&req->next, &v9ses->mux_fcalls);
spin_unlock(&v9ses->muxlock);
dprintk(DEBUG_MUX, "sending message: tag %d size %d\n", tcall->tag,
tcall->size);
ret = v9ses->transport->write(v9ses->transport, data, tcall->size);
if (ret != tcall->size) {
spin_lock(&v9ses->muxlock);
list_del(&req->next);
kfree(req->rcall);
spin_unlock(&v9ses->muxlock);
if (ret >= 0)
ret = -EREMOTEIO;
} else
ret = 0;
free_data:
kfree(data);
return ret;
}
/**
* v9fs_mux_rpc - send a request, receive a response
* @v9ses: session info structure
* @tcall: fcall to send
* @rcall: buffer to place response into
*
*/
long
v9fs_mux_rpc(struct v9fs_session_info *v9ses, struct v9fs_fcall *tcall,
struct v9fs_fcall **rcall)
{
int tid = -1;
struct v9fs_fcall *fcall = NULL;
struct v9fs_rpcreq req;
int ret = -1;
if (!v9ses)
return -EINVAL;
if (!v9ses->transport || v9ses->transport->status != Connected)
return -EIO;
if (rcall)
*rcall = NULL;
if (tcall->id != TVERSION) {
tid = v9fs_get_idpool(&v9ses->tidpool);
if (tid < 0)
return -ENOMEM;
}
tcall->tag = tid;
req.tcall = tcall;
req.err = 0;
req.rcall = NULL;
ret = v9fs_send(v9ses, &req);
if (ret < 0) {
if (tcall->id != TVERSION)
v9fs_put_idpool(tid, &v9ses->tidpool);
dprintk(DEBUG_MUX, "error %d\n", ret);
return ret;
}
ret = v9fs_recv(v9ses, &req);
fcall = req.rcall;
dprintk(DEBUG_MUX, "received: tag=%x, ret=%d\n", tcall->tag, ret);
if (ret == -ERESTARTSYS) {
if (v9ses->transport->status != Disconnected
&& tcall->id != TFLUSH) {
unsigned long flags;
dprintk(DEBUG_MUX, "flushing the tag: %d\n",
tcall->tag);
clear_thread_flag(TIF_SIGPENDING);
v9fs_t_flush(v9ses, tcall->tag);
spin_lock_irqsave(&current->sighand->siglock, flags);
recalc_sigpending();
spin_unlock_irqrestore(&current->sighand->siglock,
flags);
dprintk(DEBUG_MUX, "flushing done\n");
}
goto release_req;
} else if (ret < 0)
goto release_req;
if (!fcall)
ret = -EIO;
else {
if (fcall->id == RERROR) {
ret = v9fs_errstr2errno(fcall->params.rerror.error);
if (ret == 0) { /* string match failed */
if (fcall->params.rerror.errno)
ret = -(fcall->params.rerror.errno);
else
ret = -ESERVERFAULT;
}
} else if (fcall->id != tcall->id + 1) {
dprintk(DEBUG_ERROR,
"fcall mismatch: expected %d, got %d\n",
tcall->id + 1, fcall->id);
ret = -EIO;
}
}
release_req:
if (tcall->id != TVERSION)
v9fs_put_idpool(tid, &v9ses->tidpool);
if (rcall)
*rcall = fcall;
else
kfree(fcall);
return ret;
}
/**
* v9fs_mux_cancel_requests - cancels all pending requests
*
* @v9ses: session info structure
* @err: error code to return to the requests
*/
void v9fs_mux_cancel_requests(struct v9fs_session_info *v9ses, int err)
{
struct v9fs_rpcreq *rptr;
struct v9fs_rpcreq *rreq;
dprintk(DEBUG_MUX, " %d\n", err);
spin_lock(&v9ses->muxlock);
list_for_each_entry_safe(rreq, rptr, &v9ses->mux_fcalls, next) {
rreq->err = err;
}
spin_unlock(&v9ses->muxlock);
wake_up_all(&v9ses->read_wait);
}
/**
* v9fs_recvproc - kproc to handle demultiplexing responses
* @data: session info structure
*
*/
static int v9fs_recvproc(void *data)
{
struct v9fs_session_info *v9ses = (struct v9fs_session_info *)data;
struct v9fs_fcall *rcall = NULL;
struct v9fs_rpcreq *rptr;
struct v9fs_rpcreq *req;
struct v9fs_rpcreq *rreq;
int err = 0;
allow_signal(SIGKILL);
set_current_state(TASK_INTERRUPTIBLE);
complete(&v9ses->proccmpl);
while (!kthread_should_stop() && err >= 0) {
req = rptr = rreq = NULL;
rcall = kmalloc(v9ses->maxdata + V9FS_IOHDRSZ, GFP_KERNEL);
if (!rcall) {
eprintk(KERN_ERR, "no memory for buffers\n");
break;
}
err = read_message(v9ses, rcall, v9ses->maxdata + V9FS_IOHDRSZ);
spin_lock(&v9ses->muxlock);
if (err < 0) {
list_for_each_entry_safe(rreq, rptr, &v9ses->mux_fcalls, next) {
rreq->err = err;
}
if(err != -ERESTARTSYS)
eprintk(KERN_ERR,
"Transport error while reading message %d\n", err);
} else {
list_for_each_entry_safe(rreq, rptr, &v9ses->mux_fcalls, next) {
if (rreq->tcall->tag == rcall->tag) {
req = rreq;
req->rcall = rcall;
break;
}
}
}
if (req && (req->tcall->id == TFLUSH)) {
struct v9fs_rpcreq *treq = NULL;
list_for_each_entry_safe(treq, rptr, &v9ses->mux_fcalls, next) {
if (treq->tcall->tag ==
req->tcall->params.tflush.oldtag) {
list_del(&rptr->next);
kfree(treq->rcall);
break;
}
}
}
spin_unlock(&v9ses->muxlock);
if (!req) {
if (err >= 0)
dprintk(DEBUG_ERROR,
"unexpected response: id %d tag %d\n",
rcall->id, rcall->tag);
kfree(rcall);
}
wake_up_all(&v9ses->read_wait);
set_current_state(TASK_INTERRUPTIBLE);
}
v9ses->transport->close(v9ses->transport);
/* Inform all pending processes about the failure */
wake_up_all(&v9ses->read_wait);
if (signal_pending(current))
complete(&v9ses->proccmpl);
dprintk(DEBUG_MUX, "recvproc: end\n");
v9ses->recvproc = NULL;
return err >= 0;
}
/**
* v9fs_mux_init - initialize multiplexer (spawn kproc)
* @v9ses: session info structure
* @dev_name: mount device information (to create unique kproc)
*
*/
int v9fs_mux_init(struct v9fs_session_info *v9ses, const char *dev_name)
{
char procname[60];
strncpy(procname, dev_name, sizeof(procname));
procname[sizeof(procname) - 1] = 0;
init_waitqueue_head(&v9ses->read_wait);
init_completion(&v9ses->fcread);
init_completion(&v9ses->proccmpl);
spin_lock_init(&v9ses->muxlock);
INIT_LIST_HEAD(&v9ses->mux_fcalls);
v9ses->recvproc = NULL;
v9ses->curfcall = NULL;
v9ses->recvproc = kthread_create(v9fs_recvproc, v9ses,
"v9fs_recvproc %s", procname);
if (IS_ERR(v9ses->recvproc)) {
eprintk(KERN_ERR, "cannot create receiving thread\n");
v9fs_session_close(v9ses);
return -ECONNABORTED;
}
wake_up_process(v9ses->recvproc);
wait_for_completion(&v9ses->proccmpl);
return 0;
}