[PATCH] v9fs: transport modules

This part of the patch contains transport routines.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 440 insertions, 0 deletions

diff --git a/fs/9p/mux.c b/fs/9p/mux.c
new file mode 100644
index 000000000000..8ebc1af2c245
--- /dev/null
+++ b/fs/9p/mux.c
@@ -0,0 +1,440 @@
+/*
+ * 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) || dprintcond(v9ses, req)));
+
+        dprintk(DEBUG_MUX, "got it: rcall %p\n", req->rcall);
+        if (v9ses->transport->status == Disconnected)
+                return -ECONNRESET;
+
+        if (ret == 0) {
+                spin_lock(&v9ses->muxlock);
+                list_del(&req->next);
+                spin_unlock(&v9ses->muxlock);
+        }
+
+        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 (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.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_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);
+                if (err < 0) {
+                        kfree(rcall);
+                        break;
+                }
+                spin_lock(&v9ses->muxlock);
+                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) {
+                        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);
+        }
+
+        /* 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;
+}