source: mainline/uspace/srv/fs/minixfs/mfs.c@ 3b08178

/*
 * Copyright (c) 2006 Martin Decky
 * Copyright (c) 2008 Jakub Jermar
 * Copyright (c) 2011 Maurizio Lombardi
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup fs
 * @{
 */

/**
 * @file        mfs.c
 * @brief       Minix file system driver for HelenOS.
 */

#define _MAIN

#include <ipc/services.h>
#include <ipc/ns.h>
#include <async.h>
#include <errno.h>
#include <unistd.h>
#include <task.h>
#include <stdio.h>
#include "mfs.h"

#define NAME    "mfs"

vfs_info_t mfs_vfs_info = {
        .name = NAME,
        .concurrent_read_write = false,
        .write_retains_size = false,    
};


/**
 * This connection fibril processes VFS requests from VFS.
 *
 * In order to support simultaneous VFS requests, our design is as follows.
 * The connection fibril accepts VFS requests from VFS. If there is only one
 * instance of the fibril, VFS will need to serialize all VFS requests it sends
 * to MinixFS. To overcome this bottleneck, VFS can send MinixFS the IPC_M_CONNECT_ME_TO
 * call. In that case, a new connection fibril will be created, which in turn
 * will accept the call. Thus, a new phone will be opened for VFS.
 *
 * There are few issues with this arrangement. First, VFS can run out of
 * available phones. In that case, VFS can close some other phones or use one
 * phone for more serialized requests. Similarily, MinixFS can refuse to duplicate
 * the connection. VFS should then just make use of already existing phones and
 * route its requests through them. To avoid paying the fibril creation price 
 * upon each request, MinixFS might want to keep the connections open after the
 * request has been completed.
 */

static void mfs_connection(ipc_callid_t iid, ipc_call_t *icall)
{
        if (iid) {
                /*
                 * This only happens for connections opened by
                 * IPC_M_CONNECT_ME_TO calls as opposed to callback connections
                 * created by IPC_M_CONNECT_TO_ME.
                 */
                async_answer_0(iid, EOK);
        }
        
        printf(NAME ": connection opened\n");
        while (1) {
                ipc_callid_t callid;
                ipc_call_t call;
        
                callid = async_get_call(&call);
                switch  (IPC_GET_IMETHOD(call)) {
                case IPC_M_PHONE_HUNGUP:
                        return;
                case VFS_OUT_MOUNTED:
                        mfsdebug("Mount request received\n");
                        mfs_mounted(callid, &call);
                        break;
                case VFS_OUT_MOUNT:
                        mfs_mount(callid, &call);
                        break;
                default:
                        async_answer_0(callid, ENOTSUP);
                        break;
                }
        }
}


int main(int argc, char **argv)
{
        int vfs_phone;
        int rc;

        printf(NAME ": HelenOS Minix file system server\n");

        vfs_phone = service_connect_blocking(SERVICE_VFS, 0, 0);

        if (vfs_phone < EOK) {
                printf(NAME ": failed to connect to VFS\n");
                return -1;
        }

        rc = fs_register(vfs_phone, &mfs_reg, &mfs_vfs_info, mfs_connection);
        if (rc != EOK)
                goto err;
        
        printf(NAME ": Accepting connections\n");
        task_retval(0);
        async_manager();
        /* not reached */
        return 0;

err:
        printf(NAME ": Failed to register file system (%d)\n", rc);
        return rc;
}

/**
 * @}
 */