fs/super.c

/*
 *  linux/fs/super.c
 *
 *  (C) 1991  Linus Torvalds
 */

/*
 * super.c contains code to handle the super-block tables.
 */
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/minix_fs.h>
#include <linux/ext_fs.h>
#include <linux/kernel.h>
#include <linux/stat.h>
#include <asm/system.h>
#include <asm/segment.h>

#include <errno.h>

int sync_dev(int dev);
void wait_for_keypress(void);

/* set_bit uses setb, as gas doesn't recognize setc */
#define set_bit(bitnr,addr) ({ \
register int __res __asm__("ax"); \
__asm__("bt %2,%3;setb %%al":"=a" (__res):"a" (0),"r" (bitnr),"m" (*(addr))); \
__res; })

struct super_block super_block[NR_SUPER];
/* this is initialized in init/main.c */
int ROOT_DEV = 0;

/* Move into include file later */

static struct file_system_type file_systems[] = {
	{minix_read_super,"minix"},
	{ext_read_super,"ext"},
	{NULL,NULL}
};

/* end of include file */

struct file_system_type *get_fs_type(char *name)
{
	int a;
	
	for(a = 0 ; file_systems[a].read_super ; a++)
		if (!strcmp(name,file_systems[a].name))
			return(&file_systems[a]);
	return(NULL);
}

void lock_super(struct super_block * sb)
{
	cli();
	while (sb->s_lock)
		sleep_on(&(sb->s_wait));
	sb->s_lock = 1;
	sti();
}

void free_super(struct super_block * sb)
{
	cli();
	sb->s_lock = 0;
	wake_up(&(sb->s_wait));
	sti();
}

void wait_on_super(struct super_block * sb)
{
	cli();
	while (sb->s_lock)
		sleep_on(&(sb->s_wait));
	sti();
}

struct super_block * get_super(int dev)
{
	struct super_block * s;

	if (!dev)
		return NULL;
	s = 0+super_block;
	while (s < NR_SUPER+super_block)
		if (s->s_dev == dev) {
			wait_on_super(s);
			if (s->s_dev == dev)
				return s;
			s = 0+super_block;
		} else
			s++;
	return NULL;
}

void put_super(int dev)
{
	struct super_block * sb;

	if (dev == ROOT_DEV) {
		printk("root diskette changed: prepare for armageddon\n\r");
		return;
	}
	if (!(sb = get_super(dev)))
		return;
	if (sb->s_covered) {
		printk("Mounted disk changed - tssk, tssk\n\r");
		return;
	}
	if (sb->s_op && sb->s_op->put_super)
		sb->s_op->put_super(sb);
}

static struct super_block * read_super(int dev,char *name,void *data)
{
	struct super_block * s;
	struct file_system_type *type;

	if (!dev)
		return NULL;
	check_disk_change(dev);
	if (s = get_super(dev))
		return s;
	if (!(type=get_fs_type(name))) {
		printk("get fs type failed %s\n",name);
		return NULL;
	}
	for (s = 0+super_block ;; s++) {
		if (s >= NR_SUPER+super_block)
			return NULL;
		if (!s->s_dev)
			break;
	}
	s->s_dev = dev;
	if (!type->read_super(s,data))
		return(NULL);
	s->s_dev = dev;
	s->s_covered = NULL;
	s->s_time = 0;
	s->s_rd_only = 0;
	s->s_dirt = 0;
	return(s);
}

int sys_umount(char * dev_name)
{
	struct inode * inode;
	struct super_block * sb;
	int dev;

	if (!suser())
		return -EPERM;
	if (!(inode = namei(dev_name)))
		return -ENOENT;
	dev = inode->i_rdev;
	if (!S_ISBLK(inode->i_mode)) {
		iput(inode);
		return -ENOTBLK;
	}
	iput(inode);
	if (dev==ROOT_DEV)
		return -EBUSY;
	if (!(sb=get_super(dev)) || !(sb->s_covered))
		return -ENOENT;
	if (!sb->s_covered->i_mount)
		printk("Mounted inode has i_mount=0\n");
	for (inode = inode_table+0 ; inode < inode_table+NR_INODE ; inode++)
		if (inode->i_dev==dev && inode->i_count)
			if (inode == sb->s_mounted && inode->i_count == 1)
				continue;
			else
				return -EBUSY;
	sb->s_covered->i_mount=0;
	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);
        sync_dev(dev);
	return 0;
}

int sys_mount(char * dev_name, char * dir_name, char * type, int rw_flag)
{
	struct inode * dev_i, * dir_i;
	struct super_block * sb;
	int dev;
	char tmp[100],*t;
	int i;

	if (!suser())
		return -EPERM;
	if (!(dev_i = namei(dev_name)))
		return -ENOENT;
	dev = dev_i->i_rdev;
	if (!S_ISBLK(dev_i->i_mode)) {
		iput(dev_i);
		return -EPERM;
	}
	iput(dev_i);
	if (!(dir_i=namei(dir_name)))
		return -ENOENT;
	if (dir_i->i_count != 1 || dir_i->i_ino == MINIX_ROOT_INO) {
		iput(dir_i);
		return -EBUSY;
	}
	if (!S_ISDIR(dir_i->i_mode)) {
		iput(dir_i);
		return -EPERM;
	}
	if (dir_i->i_mount) {
		iput(dir_i);
		return -EPERM;
	}
	if (type) {
		i = 0;
		while (i < 100 && (tmp[i] = get_fs_byte(type++)))
			i++;
		t = tmp;
	} else
		t = "minix";
	if (!(sb = read_super(dev,t,NULL))) {
		iput(dir_i);
		return -EBUSY;
	}
	if (sb->s_covered) {
		iput(dir_i);
		return -EBUSY;
	}
	sb->s_covered = dir_i;
	dir_i->i_mount = 1;
	dir_i->i_dirt = 1;		/* NOTE! we don't iput(dir_i) */
	return 0;			/* we do that in umount */
}

void mount_root(void)
{
	int i,free;
	struct super_block * p;
	struct inode * mi;

	if (32 != sizeof (struct minix_inode))
		panic("bad i-node size");
	for(i=0;i<NR_FILE;i++)
		file_table[i].f_count=0;
	if (MAJOR(ROOT_DEV) == 2) {
		printk("Insert root floppy and press ENTER");
		wait_for_keypress();
	}
	for(p = &super_block[0] ; p < &super_block[NR_SUPER] ; p++) {
		p->s_dev = 0;
		p->s_lock = 0;
		p->s_wait = NULL;
	}
	if (!(p=read_super(ROOT_DEV,"minix",NULL)))
		panic("Unable to mount root");
 	/*wait_for_keypress();
	if (!(mi=iget(ROOT_DEV,MINIX_ROOT_INO)))
		panic("Unable to read root i-node");
	wait_for_keypress();*/
	mi=p->s_mounted;
	mi->i_count += 3 ;	/* NOTE! it is logically used 4 times, not 1 */
	p->s_mounted = p->s_covered = mi;
	current->pwd = mi;
	current->root = mi;
	free=0;
	i=p->s_nzones;
	while (-- i >= 0)
		if (!set_bit(i&8191,p->s_zmap[i>>13]->b_data))
			free++;
	printk("%d/%d free blocks\n\r",free,p->s_nzones);
	free=0;
	i=p->s_ninodes+1;
	while (-- i >= 0)
		if (!set_bit(i&8191,p->s_imap[i>>13]->b_data))
			free++;
	printk("%d/%d free inodes\n\r",free,p->s_ninodes);
}