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* linux/fs/super.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* super.c contains code to handle the super-block tables.
*/
#include <stdarg.h>
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/locks.h>
#include <asm/system.h>
#include <asm/segment.h>
extern struct file_operations * get_blkfops(unsigned int);
extern struct file_operations * get_chrfops(unsigned int);
extern void wait_for_keypress(void);
extern void fcntl_init_locks(void);
extern int root_mountflags;
struct super_block super_blocks[NR_SUPER];
static int do_remount_sb(struct super_block *sb, int flags, char * data);
/* this is initialized in init/main.c */
dev_t ROOT_DEV = 0;
static struct file_system_type * file_systems = NULL;
int register_filesystem(struct file_system_type * fs)
{
struct file_system_type ** tmp;
if (!fs)
return -EINVAL;
if (fs->next)
return -EBUSY;
tmp = &file_systems;
while (*tmp) {
if (strcmp((*tmp)->name, fs->name) == 0)
return -EBUSY;
tmp = &(*tmp)->next;
}
*tmp = fs;
return 0;
}
int unregister_filesystem(struct file_system_type * fs)
{
struct file_system_type ** tmp;
tmp = &file_systems;
while (*tmp) {
if (fs == *tmp) {
*tmp = fs->next;
fs->next = NULL;
return 0;
}
tmp = &(*tmp)->next;
}
return -EINVAL;
}
static int fs_index(const char * __name)
{
struct file_system_type * tmp;
char * name;
int err, index;
err = getname(__name, &name);
if (err)
return err;
index = 0;
for (tmp = file_systems ; tmp ; tmp = tmp->next) {
if (strcmp(tmp->name, name) == 0) {
putname(name);
return index;
}
index++;
}
putname(name);
return -EINVAL;
}
static int fs_name(unsigned int index, char * buf)
{
struct file_system_type * tmp;
int err, len;
tmp = file_systems;
while (tmp && index > 0) {
tmp = tmp->next;
index--;
}
if (!tmp)
return -EINVAL;
len = strlen(tmp->name) + 1;
err = verify_area(VERIFY_WRITE, buf, len);
if (err)
return err;
memcpy_tofs(buf, tmp->name, len);
return 0;
}
static int fs_maxindex(void)
{
struct file_system_type * tmp;
int index;
index = 0;
for (tmp = file_systems ; tmp ; tmp = tmp->next)
index++;
return index;
}
/*
* Whee.. Weird sysv syscall.
*/
asmlinkage int sys_sysfs(int option, ...)
{
va_list args;
int retval = -EINVAL;
unsigned int index;
va_start(args, option);
switch (option) {
case 1:
retval = fs_index(va_arg(args, const char *));
break;
case 2:
index = va_arg(args, unsigned int);
retval = fs_name(index, va_arg(args, char *));
break;
case 3:
retval = fs_maxindex();
break;
}
va_end(args);
return retval;
}
int get_filesystem_list(char * buf)
{
int len = 0;
struct file_system_type * tmp;
tmp = file_systems;
while (tmp && len < PAGE_SIZE - 80) {
len += sprintf(buf+len, "%s\t%s\n",
tmp->requires_dev ? "" : "nodev",
tmp->name);
tmp = tmp->next;
}
return len;
}
struct file_system_type *get_fs_type(char *name)
{
struct file_system_type * fs = file_systems;
if (!name)
return fs;
while (fs) {
if (!strcmp(name,fs->name))
break;
fs = fs->next;
}
return fs;
}
void __wait_on_super(struct super_block * sb)
{
struct wait_queue wait = { current, NULL };
add_wait_queue(&sb->s_wait, &wait);
repeat:
current->state = TASK_UNINTERRUPTIBLE;
if (sb->s_lock) {
schedule();
goto repeat;
}
remove_wait_queue(&sb->s_wait, &wait);
current->state = TASK_RUNNING;
}
void sync_supers(dev_t dev)
{
struct super_block * sb;
for (sb = super_blocks + 0 ; sb < super_blocks + NR_SUPER ; sb++) {
if (!sb->s_dev)
continue;
if (dev && sb->s_dev != dev)
continue;
wait_on_super(sb);
if (!sb->s_dev || !sb->s_dirt)
continue;
if (dev && (dev != sb->s_dev))
continue;
if (sb->s_op && sb->s_op->write_super)
sb->s_op->write_super(sb);
}
}
static struct super_block * get_super(dev_t dev)
{
struct super_block * s;
if (!dev)
return NULL;
s = 0+super_blocks;
while (s < NR_SUPER+super_blocks)
if (s->s_dev == dev) {
wait_on_super(s);
if (s->s_dev == dev)
return s;
s = 0+super_blocks;
} else
s++;
return NULL;
}
void put_super(dev_t dev)
{
struct super_block * sb;
if (dev == ROOT_DEV) {
printk("VFS: Root device %d/%d: prepare for armageddon\n",
MAJOR(dev), MINOR(dev));
return;
}
if (!(sb = get_super(dev)))
return;
if (sb->s_covered) {
printk("VFS: Mounted device %d/%d - tssk, tssk\n",
MAJOR(dev), MINOR(dev));
return;
}
if (sb->s_op && sb->s_op->put_super)
sb->s_op->put_super(sb);
}
static struct super_block * read_super(dev_t dev,char *name,int flags,
void *data, int silent)
{
struct super_block * s;
struct file_system_type *type;
if (!dev)
return NULL;
check_disk_change(dev);
s = get_super(dev);
if (s)
return s;
if (!(type = get_fs_type(name))) {
printk("VFS: on device %d/%d: get_fs_type(%s) failed\n",
MAJOR(dev), MINOR(dev), name);
return NULL;
}
for (s = 0+super_blocks ;; s++) {
if (s >= NR_SUPER+super_blocks)
return NULL;
if (!s->s_dev)
break;
}
s->s_dev = dev;
s->s_flags = flags;
if (!type->read_super(s,data, silent)) {
s->s_dev = 0;
return NULL;
}
s->s_dev = dev;
s->s_covered = NULL;
s->s_rd_only = 0;
s->s_dirt = 0;
return s;
}
/*
* Unnamed block devices are dummy devices used by virtual
* filesystems which don't use real block-devices. -- jrs
*/
static char unnamed_dev_in_use[256];
static dev_t get_unnamed_dev(void)
{
static int first_use = 0;
int i;
if (first_use == 0) {
first_use = 1;
memset(unnamed_dev_in_use, 0, sizeof(unnamed_dev_in_use));
unnamed_dev_in_use[0] = 1; /* minor 0 (nodev) is special */
}
for (i = 0; i < sizeof unnamed_dev_in_use/sizeof unnamed_dev_in_use[0]; i++) {
if (!unnamed_dev_in_use[i]) {
unnamed_dev_in_use[i] = 1;
return (UNNAMED_MAJOR << 8) | i;
}
}
return 0;
}
static void put_unnamed_dev(dev_t dev)
{
if (!dev)
return;
if (!unnamed_dev_in_use[dev]) {
printk("VFS: put_unnamed_dev: freeing unused device %d/%d\n",
MAJOR(dev), MINOR(dev));
return;
}
unnamed_dev_in_use[dev] = 0;
}
static int do_umount(dev_t dev)
{
struct super_block * sb;
int retval;
if (dev==ROOT_DEV) {
/* Special case for "unmounting" root. We just try to remount
it readonly, and sync() the device. */
if (!(sb=get_super(dev)))
return -ENOENT;
if (!(sb->s_flags & MS_RDONLY)) {
fsync_dev(dev);
retval = do_remount_sb(sb, MS_RDONLY, 0);
if (retval)
return retval;
}
return 0;
}
if (!(sb=get_super(dev)) || !(sb->s_covered))
return -ENOENT;
if (!sb->s_covered->i_mount)
printk("VFS: umount(%d/%d): mounted inode has i_mount=NULL\n",
MAJOR(dev), MINOR(dev));
if (!fs_may_umount(dev, sb->s_mounted))
return -EBUSY;
sb->s_covered->i_mount = NULL;
iput(sb->s_covered);
sb->s_covered = NULL;
iput(sb->s_mounted);
sb->s_mounted = NULL;
if (sb->s_op && sb->s_op->write_super && sb->s_dirt)
sb->s_op->write_super(sb);
put_super(dev);
return 0;
}
/*
* Now umount can handle mount points as well as block devices.
* This is important for filesystems which use unnamed block devices.
*
* There is a little kludge here with the dummy_inode. The current
* vfs release functions only use the r_dev field in the inode so
* we give them the info they need without using a real inode.
* If any other fields are ever needed by any block device release
* functions, they should be faked here. -- jrs
*/
asmlinkage int sys_umount(char * name)
{
struct inode * inode;
dev_t dev;
int retval;
struct inode dummy_inode;
struct file_operations * fops;
if (!suser())
return -EPERM;
retval = namei(name,&inode);
if (retval) {
retval = lnamei(name,&inode);
if (retval)
return retval;
}
if (S_ISBLK(inode->i_mode)) {
dev = inode->i_rdev;
if (IS_NODEV(inode)) {
iput(inode);
return -EACCES;
}
} else {
if (!inode || !inode->i_sb || inode != inode->i_sb->s_mounted) {
iput(inode);
return -EINVAL;
}
dev = inode->i_sb->s_dev;
iput(inode);
memset(&dummy_inode, 0, sizeof(dummy_inode));
dummy_inode.i_rdev = dev;
inode = &dummy_inode;
}
if (MAJOR(dev) >= MAX_BLKDEV) {
iput(inode);
return -ENXIO;
}
if (!(retval = do_umount(dev)) && dev != ROOT_DEV) {
fops = get_blkfops(MAJOR(dev));
if (fops && fops->release)
fops->release(inode,NULL);
if (MAJOR(dev) == UNNAMED_MAJOR)
put_unnamed_dev(dev);
}
if (inode != &dummy_inode)
iput(inode);
if (retval)
return retval;
fsync_dev(dev);
return 0;
}
/*
* do_mount() does the actual mounting after sys_mount has done the ugly
* parameter parsing. When enough time has gone by, and everything uses the
* new mount() parameters, sys_mount() can then be cleaned up.
*
* We cannot mount a filesystem if it has active, used, or dirty inodes.
* We also have to flush all inode-data for this device, as the new mount
* might need new info.
*/
static int do_mount(dev_t dev, const char * dir, char * type, int flags, void * data)
{
struct inode * dir_i;
struct super_block * sb;
int error;
error = namei(dir,&dir_i);
if (error)
return error;
if (dir_i->i_count != 1 || dir_i->i_mount) {
iput(dir_i);
return -EBUSY;
}
if (!S_ISDIR(dir_i->i_mode)) {
iput(dir_i);
return -EPERM;
}
if (!fs_may_mount(dev)) {
iput(dir_i);
return -EBUSY;
}
sb = read_super(dev,type,flags,data,0);
if (!sb || sb->s_covered) {
iput(dir_i);
return -EBUSY;
}
sb->s_covered = dir_i;
dir_i->i_mount = sb->s_mounted;
return 0; /* we don't iput(dir_i) - see umount */
}
/*
* Alters the mount flags of a mounted file system. Only the mount point
* is used as a reference - file system type and the device are ignored.
* FS-specific mount options can't be altered by remounting.
*/
static int do_remount_sb(struct super_block *sb, int flags, char *data)
{
int retval;
/* If we are remounting RDONLY, make sure there are no rw files open */
if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY))
if (!fs_may_remount_ro(sb->s_dev))
return -EBUSY;
if (sb->s_op && sb->s_op->remount_fs) {
retval = sb->s_op->remount_fs(sb, &flags, data);
if (retval)
return retval;
}
sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) |
(flags & MS_RMT_MASK);
return 0;
}
static int do_remount(const char *dir,int flags,char *data)
{
struct inode *dir_i;
int retval;
retval = namei(dir,&dir_i);
if (retval)
return retval;
if (dir_i != dir_i->i_sb->s_mounted) {
iput(dir_i);
return -EINVAL;
}
retval = do_remount_sb(dir_i->i_sb, flags, data);
iput(dir_i);
return retval;
}
static int copy_mount_options (const void * data, unsigned long *where)
{
int i;
unsigned long page;
struct vm_area_struct * vma;
*where = 0;
if (!data)
return 0;
for (vma = current->mm->mmap ; ; ) {
if (!vma ||
(unsigned long) data < vma->vm_start) {
return -EFAULT;
}
if ((unsigned long) data < vma->vm_end)
break;
vma = vma->vm_next;
}
i = vma->vm_end - (unsigned long) data;
if (PAGE_SIZE <= (unsigned long) i)
i = PAGE_SIZE-1;
if (!(page = __get_free_page(GFP_KERNEL))) {
return -ENOMEM;
}
memcpy_fromfs((void *) page,data,i);
*where = page;
return 0;
}
/*
* Flags is a 16-bit value that allows up to 16 non-fs dependent flags to
* be given to the mount() call (ie: read-only, no-dev, no-suid etc).
*
* data is a (void *) that can point to any structure up to
* PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
* information (or be NULL).
*
* NOTE! As old versions of mount() didn't use this setup, the flags
* has to have a special 16-bit magic number in the hight word:
* 0xC0ED. If this magic word isn't present, the flags and data info
* isn't used, as the syscall assumes we are talking to an older
* version that didn't understand them.
*/
asmlinkage int sys_mount(char * dev_name, char * dir_name, char * type,
unsigned long new_flags, void * data)
{
struct file_system_type * fstype;
struct inode * inode;
struct file_operations * fops;
dev_t dev;
int retval;
char * t;
unsigned long flags = 0;
unsigned long page = 0;
if (!suser())
return -EPERM;
if ((new_flags &
(MS_MGC_MSK | MS_REMOUNT)) == (MS_MGC_VAL | MS_REMOUNT)) {
retval = copy_mount_options (data, &page);
if (retval < 0)
return retval;
retval = do_remount(dir_name,
new_flags & ~MS_MGC_MSK & ~MS_REMOUNT,
(char *) page);
free_page(page);
return retval;
}
retval = copy_mount_options (type, &page);
if (retval < 0)
return retval;
fstype = get_fs_type((char *) page);
free_page(page);
if (!fstype)
return -ENODEV;
t = fstype->name;
if (fstype->requires_dev) {
retval = namei(dev_name,&inode);
if (retval)
return retval;
if (!S_ISBLK(inode->i_mode)) {
iput(inode);
return -ENOTBLK;
}
if (IS_NODEV(inode)) {
iput(inode);
return -EACCES;
}
dev = inode->i_rdev;
if (MAJOR(dev) >= MAX_BLKDEV) {
iput(inode);
return -ENXIO;
}
} else {
if (!(dev = get_unnamed_dev()))
return -EMFILE;
inode = NULL;
}
fops = get_blkfops(MAJOR(dev));
if (fops && fops->open) {
retval = fops->open(inode,NULL);
if (retval) {
iput(inode);
return retval;
}
}
page = 0;
if ((new_flags & MS_MGC_MSK) == MS_MGC_VAL) {
flags = new_flags & ~MS_MGC_MSK;
retval = copy_mount_options(data, &page);
if (retval < 0) {
iput(inode);
return retval;
}
}
retval = do_mount(dev,dir_name,t,flags,(void *) page);
free_page(page);
if (retval && fops && fops->release)
fops->release(inode,NULL);
iput(inode);
return retval;
}
void mount_root(void)
{
struct file_system_type * fs_type;
struct super_block * sb;
struct inode * inode;
memset(super_blocks, 0, sizeof(super_blocks));
fcntl_init_locks();
if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
printk(KERN_NOTICE "VFS: Insert root floppy and press ENTER\n");
wait_for_keypress();
}
for (fs_type = file_systems ; fs_type ; fs_type = fs_type->next) {
if (!fs_type->requires_dev)
continue;
sb = read_super(ROOT_DEV,fs_type->name,root_mountflags,NULL,1);
if (sb) {
inode = sb->s_mounted;
inode->i_count += 3 ; /* NOTE! it is logically used 4 times, not 1 */
sb->s_covered = inode;
sb->s_flags = root_mountflags;
current->fs->pwd = inode;
current->fs->root = inode;
printk ("VFS: Mounted root (%s filesystem)%s.\n",
fs_type->name,
(sb->s_flags & MS_RDONLY) ? " readonly" : "");
return;
}
}
panic("VFS: Unable to mount root fs on %02x:%02x",
MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
}
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