File: [local] / prex / usr / server / fs / vfs / vfs_mount.c (download)
Revision 1.1.1.1 (vendor branch), Tue Aug 19 12:47:01 2008 UTC (16 years ago) by nbrk
Branch: MAIN, KOHSUKE
CVS Tags: PREX_0_8_BASE, HEAD Changes since 1.1: +0 -0 lines
Initial import of Prex, Portable Real-time Embedded POSIX microkernel system.
I have totally new directions in my development (more focused on real hardware, not virtual one).
Old hacks are available in prex-old module. They will be carefully re-designed and merged soon.
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/*
* Copyright (c) 2005-2007, Kohsuke Ohtani
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*/
/*
* mount.c - mount operations
*/
#include <prex/prex.h>
#include <sys/stat.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/mount.h>
#include <sys/dirent.h>
#include <sys/list.h>
#include <sys/buf.h>
#include <limits.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include "vfs.h"
/*
* List for VFS mount points.
*/
static struct list mount_list = LIST_INIT(mount_list);
/*
* Global lock to access mount point.
*/
#if CONFIG_FS_THREADS > 1
static mutex_t mount_lock = MUTEX_INITIALIZER;
#define MOUNT_LOCK() mutex_lock(&mount_lock)
#define MOUNT_UNLOCK() mutex_unlock(&mount_lock)
#else
#define MOUNT_LOCK()
#define MOUNT_UNLOCK()
#endif
/*
* Lookup file system.
*/
static const struct vfssw *
fs_lookup(char *name)
{
const struct vfssw *fs;
for (fs = vfssw_table; fs->vs_name; fs++) {
if (!strncmp(name, fs->vs_name, FSMAXNAMES))
break;
}
if (!fs->vs_name)
return NULL;
return fs;
}
int
sys_mount(char *dev, char *dir, char *fsname, int flags, void *data)
{
const struct vfssw *fs;
mount_t mp;
list_t head, n;
device_t device;
vnode_t vp, vp_covered;
int err;
dprintf("VFS: Mounting %s dev=%s dir=%s\n", fsname, dev, dir);
if (!dir || *dir == '\0')
return ENOENT;
/* Find a file system. */
if (!(fs = fs_lookup(fsname)))
return ENODEV; /* No such file system */
/* Open device. NULL can be specified as a device. */
device = 0;
if (*dev != '\0') {
if (strncmp(dev, "/dev/", 5))
return ENOTBLK;
if ((err = device_open(dev + 5, DO_RDWR, &device)) != 0)
return err;
}
MOUNT_LOCK();
/* Check if device or directory has already been mounted. */
head = &mount_list;
for (n = list_first(head); n != head; n = list_next(n)) {
mp = list_entry(n, struct mount, m_link);
if (!strcmp(mp->m_path, dir) ||
(device && mp->m_dev == (dev_t)device)) {
err = EBUSY; /* Already mounted */
goto err1;
}
}
/*
* Create VFS mount entry
*/
if (!(mp = malloc(sizeof(struct mount)))) {
err = ENOMEM;
goto err1;
}
mp->m_count = 0;
mp->m_op = fs->vs_op;
mp->m_flags = flags;
mp->m_dev = (dev_t)device;
strlcpy(mp->m_path, dir, PATH_MAX);
mp->m_path[PATH_MAX - 1] = '\0';
/*
* Get vnode to be covered in the upper file system.
*/
if (*dir == '/' && *(dir + 1) == '\0') {
/* Ignore if it mounts to global root directory. */
vp_covered = NULL;
} else {
if ((err = namei(dir, &vp_covered)) != 0) {
err = ENOENT;
goto err2;
}
if (vp_covered->v_type != VDIR) {
err = ENOTDIR;
goto err3;
}
}
mp->m_covered = vp_covered;
/*
* Create a root vnode for this file system.
*/
if ((vp = vget(mp, "/")) == NULL) {
err = ENOMEM;
goto err3;
}
vp->v_type = VDIR;
vp->v_flags = VROOT;
vp->v_mode = S_IFDIR | S_IRUSR | S_IRGRP | S_IROTH;
mp->m_root = vp;
/*
* Call a file system specific routine to mount.
*/
if ((err = VFS_MOUNT(mp, dev, flags, data)) != 0)
goto err4;
/*
* Keep reference count for root/covered vnode.
*/
vn_unlock(vp);
if (vp_covered)
vn_unlock(vp_covered);
/*
* Insert to mount list
*/
list_insert(&mount_list, &mp->m_link);
MOUNT_UNLOCK();
return 0;
err4:
vput(vp);
err3:
if (vp_covered)
vput(vp_covered);
err2:
free(mp);
err1:
device_close(device);
MOUNT_UNLOCK();
return err;
}
int
sys_umount(char *path)
{
mount_t mp;
list_t head, n;
int err;
DPRINTF(VFSDB_SYSCALL, ("sys_umount: path=%s\n", path));
MOUNT_LOCK();
/* Get mount entry */
head = &mount_list;
for (n = list_first(head); n != head; n = list_next(n)) {
mp = list_entry(n, struct mount, m_link);
if (!strcmp(path, mp->m_path))
break;
}
if (n == head) {
err = EINVAL;
goto out;
}
/*
* Root fs can not be unmounted.
*/
if (mp->m_covered == NULL) {
err = EINVAL;
goto out;
}
if ((err = VFS_UNMOUNT(mp)) != 0)
goto out;
list_remove(&mp->m_link);
/* Decrement referece count of root vnode */
vrele(mp->m_covered);
/* Release all vnodes */
vflush(mp);
/* Flush all buffers */
binval(mp->m_dev);
if (mp->m_dev)
device_close((device_t)mp->m_dev);
free(mp);
out:
MOUNT_UNLOCK();
return err;
}
int
sys_sync(void)
{
mount_t mp;
list_t head, n;
/* Call each mounted file system. */
MOUNT_LOCK();
head = &mount_list;
for (n = list_first(head); n != head; n = list_next(n)) {
mp = list_entry(n, struct mount, m_link);
VFS_SYNC(mp);
}
MOUNT_UNLOCK();
bio_sync();
return 0;
}
/*
* Compare two path strings. Return matched length.
* @path: target path.
* @root: vfs root path as mount point.
*/
static size_t
count_match(char *path, char *mount_root)
{
size_t len = 0;
while (*path && *mount_root) {
if (*path++ != *mount_root++)
break;
len++;
}
if (*mount_root != '\0')
return 0;
if (len == 1 && *(path - 1) == '/')
return 1;
if (*path == '\0' || *path == '/')
return len;
return 0;
}
/*
* Get the root directory and mount point for specified path.
* @path: full path.
* @mp: mount point to return.
* @root: pointer to root directory in path.
*/
int
vfs_findroot(char *path, mount_t *mp, char **root)
{
mount_t m, tmp;
list_t head, n;
size_t len, max_len = 0;
if (!path)
return -1;
/* Find mount point from nearest path */
MOUNT_LOCK();
m = NULL;
head = &mount_list;
for (n = list_first(head); n != head; n = list_next(n)) {
tmp = list_entry(n, struct mount, m_link);
len = count_match(path, tmp->m_path);
if (len > max_len) {
max_len = len;
m = tmp;
}
}
MOUNT_UNLOCK();
if (m == NULL)
return -1;
*root = (char *)(path + max_len);
if (**root == '/')
(*root)++;
*mp = m;
return 0;
}
/*
* Mark a mount point as busy.
*/
void
vfs_busy(mount_t mp)
{
MOUNT_LOCK();
mp->m_count++;
MOUNT_UNLOCK();
}
/*
* Mark a mount point as busy.
*/
void
vfs_unbusy(mount_t mp)
{
MOUNT_LOCK();
mp->m_count--;
MOUNT_UNLOCK();
}
int
vfs_nullop(void)
{
return 0;
}
int
vfs_einval(void)
{
return EINVAL;
}
#ifdef DEBUG
void
mount_dump(void)
{
list_t head, n;
mount_t mp;
MOUNT_LOCK();
dprintf("mount_dump\n");
dprintf("dev count root\n");
dprintf("-------- ----- --------\n");
head = &mount_list;
for (n = list_first(head); n != head; n = list_next(n)) {
mp = list_entry(n, struct mount, m_link);
dprintf("%8x %5d %s\n", mp->m_dev, mp->m_count, mp->m_path);
}
MOUNT_UNLOCK();
}
#endif