Subversion Repositories HelenOS

/*

 * Copyright (c) 2006 Martin Decky

 * Copyright (c) 2008 Jakub Jermar

 * 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    tmpfs.c

 * @brief   File system driver for in-memory file system.

 *

 * Every instance of tmpfs exists purely in memory and has neither a disk layout

 * nor any permanent storage (e.g. disk blocks). With each system reboot, data

 * stored in a tmpfs file system is lost.

 */

#include "tmpfs.h"

#include <ipc/ipc.h>

#include <ipc/services.h>

#include <async.h>

#include <errno.h>

#include <unistd.h>

#include <stdio.h>

#include <libfs.h>

#include "../../vfs/vfs.h"

#define NAME "tmpfs"

vfs_info_t tmpfs_vfs_info = {

    .name = "tmpfs",

    .ops = {

        [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_TRUNCATE)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_MOUNTED)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_NULL,

        [IPC_METHOD_TO_VFS_OP(VFS_DESTROY)] = VFS_OP_DEFINED,

    }

};

fs_reg_t tmpfs_reg;

/**

 * 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 FAT. To overcome this bottleneck, VFS can send TMPFS 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, TMPFS 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, TMPFS might want to keep the connections open after the

 * request has been completed.

 */

static void tmpfs_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.

         */

        ipc_answer_0(iid, EOK);

    }

    dprintf("VFS-TMPFS connection established.\n");

    while (1) {

        ipc_callid_t callid;

        ipc_call_t call;

        callid = async_get_call(&call);

        switch  (IPC_GET_METHOD(call)) {

        case VFS_MOUNTED:

            tmpfs_mounted(callid, &call);

            break;

        case VFS_MOUNT:

            tmpfs_mount(callid, &call);

            break;

        case VFS_LOOKUP:

            tmpfs_lookup(callid, &call);

            break;

        case VFS_READ:

            tmpfs_read(callid, &call);

            break;

        case VFS_WRITE:

            tmpfs_write(callid, &call);

            break;

        case VFS_TRUNCATE:

            tmpfs_truncate(callid, &call);

            break;

        case VFS_DESTROY:

            tmpfs_destroy(callid, &call);

            break;

        default:

            ipc_answer_0(callid, ENOTSUP);

            break;

        }

    }

}

int main(int argc, char **argv)

{

    int vfs_phone;

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

    vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);

    while (vfs_phone < EOK) {

        usleep(10000);

        vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);

    }

    int rc;

    rc = fs_register(vfs_phone, &tmpfs_reg, &tmpfs_vfs_info,

        tmpfs_connection);

    if (rc != EOK) {

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

        return rc;

    }

    printf(NAME ": Accepting connections\n");

    async_manager();

    /* not reached */

    return 0;

}

/**

 * @}

 */