/*
* Copyright (c) 2007 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 vfs_mount.c
* @brief VFS_MOUNT method.
*/
#include <ipc/ipc.h>
#include <async.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <bool.h>
#include <futex.h>
#include <libadt/list.h>
#include "vfs.h"
atomic_t rootfs_futex = FUTEX_INITIALIZER;
vfs_triplet_t rootfs = {
.fs_handle = 0,
.dev_handle = 0,
.index = 0,
};
static int lookup_root(int fs_handle, int dev_handle, vfs_triplet_t *root)
{
vfs_pair_t altroot = {
.fs_handle = fs_handle,
.dev_handle = dev_handle,
};
return vfs_lookup_internal
("/", strlen("/"), root
, &altroot
);
}
void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
{
int dev_handle;
vfs_node_t *mp_node = NULL;
/*
* We expect the library to do the device-name to device-handle
* translation for us, thus the device handle will arrive as ARG1
* in the request.
*/
dev_handle = IPC_GET_ARG1(*request);
/*
* For now, don't make use of ARG2 and ARG3, but they can be used to
* carry mount options in the future.
*/
/*
* Now, we expect the client to send us data with the name of the file
* system and the path of the mountpoint.
*/
ipc_callid_t callid;
size_t size;
if (!ipc_data_receive(&callid, NULL, &size)) {
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
/*
* There is no sense in receiving data that can't hold a single
* character of path. We won't accept data that exceed certain limits
* either.
*/
if ((size < FS_NAME_MAXLEN + 1) ||
(size > FS_NAME_MAXLEN + MAX_PATH_LEN)) {
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
/*
* Allocate buffer for the data being received.
*/
uint8_t *buf;
if (!buf) {
ipc_answer_0(callid, ENOMEM);
ipc_answer_0(rid, ENOMEM);
return;
}
/*
* Deliver the data.
*/
(void) ipc_data_deliver(callid, buf, size);
char fs_name[FS_NAME_MAXLEN + 1];
memcpy(fs_name
, buf
, FS_NAME_MAXLEN
);
fs_name[FS_NAME_MAXLEN] = '\0';
/*
* Check if we know a file system with the same name as is in fs_name.
* This will also give us its file system handle.
*/
int fs_handle = fs_name_to_handle(fs_name, true);
if (!fs_handle) {
ipc_answer_0(rid, ENOENT);
return;
}
/*
* Lookup the root node of the filesystem being mounted.
* In this case, we don't need to take the unlink_futex as the root node
* cannot be removed. However, we do take a reference to it so that
* we can track how many times it has been mounted.
*/
int rc;
vfs_triplet_t mounted_root;
rc = lookup_root(fs_handle, dev_handle, &mounted_root);
if (rc != EOK) {
ipc_answer_0(rid, rc);
return;
}
vfs_node_t *mr_node = vfs_node_get(&mounted_root);
if (!mr_node) {
ipc_answer_0(rid, ENOMEM);
return;
}
/*
* Finally, we need to resolve the path to the mountpoint.
*/
vfs_triplet_t mp;
futex_down(&rootfs_futex);
if (rootfs.fs_handle) {
/*
* We already have the root FS.
*/
futex_down(&unlink_futex);
rc = vfs_lookup_internal((char *) (buf + FS_NAME_MAXLEN),
size - FS_NAME_MAXLEN, &mp, NULL);
if (rc != EOK) {
/*
* The lookup failed for some reason.
*/
futex_up(&unlink_futex);
futex_up(&rootfs_futex);
vfs_node_put(mr_node); /* failed -> drop reference */
ipc_answer_0(rid, rc);
return;
}
mp_node = vfs_node_get(&mp);
if (!mp_node) {
futex_up(&unlink_futex);
futex_up(&rootfs_futex);
vfs_node_put(mr_node); /* failed -> drop reference */
ipc_answer_0(rid, ENOMEM);
return;
}
/*
* Now we hold a reference to mp_node.
* It will be dropped upon the corresponding VFS_UNMOUNT.
* This prevents the mount point from being deleted.
*/
futex_up(&unlink_futex);
} else {
/*
* We still don't have the root file system mounted.
*/
if ((size
- FS_NAME_MAXLEN
== strlen("/")) &&
(buf[FS_NAME_MAXLEN] == '/')) {
/*
* For this simple, but important case, we are done.
*/
rootfs = mounted_root;
futex_up(&rootfs_futex);
ipc_answer_0(rid, EOK);
return;
} else {
/*
* We can't resolve this without the root filesystem
* being mounted first.
*/
futex_up(&rootfs_futex);
vfs_node_put(mr_node); /* failed -> drop reference */
ipc_answer_0(rid, ENOENT);
return;
}
}
futex_up(&rootfs_futex);
free(buf
); /* The buffer is not needed anymore. */
/*
* At this point, we have all necessary pieces: file system and device
* handles, and we know the mount point VFS node and also the root node
* of the file system being mounted.
*/
int phone = vfs_grab_phone(mp.fs_handle);
/* Later we can use ARG3 to pass mode/flags. */
aid_t req1 = async_send_3(phone, VFS_MOUNT, (ipcarg_t) mp.dev_handle,
(ipcarg_t) mp.index, 0, NULL);
/* The second call uses the same method. */
aid_t req2 = async_send_3(phone, VFS_MOUNT,
(ipcarg_t) mounted_root.fs_handle,
(ipcarg_t) mounted_root.dev_handle, (ipcarg_t) mounted_root.index,
NULL);
ipcarg_t rc1;
ipcarg_t rc2;
async_wait_for(req1, &rc1);
async_wait_for(req2, &rc2);
vfs_release_phone(phone);
if ((rc1 != EOK) || (rc2 != EOK)) {
/* Mount failed, drop references to mr_node and mp_node. */
vfs_node_put(mr_node);
if (mp_node)
vfs_node_put(mp_node);
}
if (rc2 == EOK)
ipc_answer_0(rid, rc1);
else if (rc1 == EOK)
ipc_answer_0(rid, rc2);
else
ipc_answer_0(rid, rc1);
}
/**
* @}
*/