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a428fcb46a
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/*
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* linux/fs/super.c
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*
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* (C) 1991 Linus Torvalds
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*/
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/*
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* super.c contains code to handle the super-block tables.
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*/
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#include <linux/config.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <asm/system.h>
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#include <errno.h>
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#include <sys/stat.h>
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int sync_dev(int dev);
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void wait_for_keypress(void);
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/* set_bit uses setb, as gas doesn't recognize setc */
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#define set_bit(bitnr,addr) ({ \
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register int __res __asm__("ax"); \
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__asm__("bt %2,%3;setb %%al":"=a" (__res):"a" (0),"r" (bitnr),"m" (*(addr))); \
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__res; })
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struct super_block super_block[NR_SUPER];
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/* this is initialized in init/main.c */
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int ROOT_DEV = 0;
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static void lock_super(struct super_block * sb)
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{
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cli();
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while (sb->s_lock)
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sleep_on(&(sb->s_wait));
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sb->s_lock = 1;
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sti();
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}
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static void free_super(struct super_block * sb)
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{
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cli();
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sb->s_lock = 0;
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wake_up(&(sb->s_wait));
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sti();
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}
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static void wait_on_super(struct super_block * sb)
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{
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cli();
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while (sb->s_lock)
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sleep_on(&(sb->s_wait));
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sti();
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}
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struct super_block * get_super(int dev)
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{
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struct super_block * s;
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if (!dev)
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return NULL;
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s = 0+super_block;
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while (s < NR_SUPER+super_block)
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if (s->s_dev == dev) {
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wait_on_super(s);
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if (s->s_dev == dev)
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return s;
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s = 0+super_block;
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} else
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s++;
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return NULL;
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}
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void put_super(int dev)
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{
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struct super_block * sb;
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/* struct m_inode * inode; */
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int i;
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if (dev == ROOT_DEV) {
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printk("root diskette changed: prepare for armageddon\n\r");
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return;
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}
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if (!(sb = get_super(dev)))
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return;
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if (sb->s_imount) {
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printk("Mounted disk changed - tssk, tssk\n\r");
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return;
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}
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lock_super(sb);
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sb->s_dev = 0;
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for(i=0;i<I_MAP_SLOTS;i++)
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brelse(sb->s_imap[i]);
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for(i=0;i<Z_MAP_SLOTS;i++)
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brelse(sb->s_zmap[i]);
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free_super(sb);
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return;
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}
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static struct super_block * read_super(int dev)
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{
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struct super_block * s;
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struct buffer_head * bh;
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int i,block;
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if (!dev)
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return NULL;
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check_disk_change(dev);
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if (s = get_super(dev))
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return s;
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for (s = 0+super_block ;; s++) {
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if (s >= NR_SUPER+super_block)
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return NULL;
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if (!s->s_dev)
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break;
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}
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s->s_dev = dev;
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s->s_isup = NULL;
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s->s_imount = NULL;
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s->s_time = 0;
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s->s_rd_only = 0;
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s->s_dirt = 0;
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lock_super(s);
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if (!(bh = bread(dev,1))) {
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s->s_dev=0;
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free_super(s);
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return NULL;
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}
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__asm__ volatile ("cld"); /* by wyj */
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*((struct d_super_block *) s) =
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*((struct d_super_block *) bh->b_data);
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brelse(bh);
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if (s->s_magic != SUPER_MAGIC) {
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s->s_dev = 0;
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free_super(s);
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return NULL;
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}
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for (i=0;i<I_MAP_SLOTS;i++)
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s->s_imap[i] = NULL;
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for (i=0;i<Z_MAP_SLOTS;i++)
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s->s_zmap[i] = NULL;
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block=2;
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for (i=0 ; i < s->s_imap_blocks ; i++)
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if (s->s_imap[i]=bread(dev,block))
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block++;
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else
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break;
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for (i=0 ; i < s->s_zmap_blocks ; i++)
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if (s->s_zmap[i]=bread(dev,block))
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block++;
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else
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break;
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if (block != 2+s->s_imap_blocks+s->s_zmap_blocks) {
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for(i=0;i<I_MAP_SLOTS;i++)
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brelse(s->s_imap[i]);
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for(i=0;i<Z_MAP_SLOTS;i++)
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brelse(s->s_zmap[i]);
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s->s_dev=0;
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free_super(s);
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return NULL;
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}
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s->s_imap[0]->b_data[0] |= 1;
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s->s_zmap[0]->b_data[0] |= 1;
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free_super(s);
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return s;
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}
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int sys_umount(char * dev_name)
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{
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struct m_inode * inode;
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struct super_block * sb;
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int dev;
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if (!(inode=namei(dev_name)))
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return -ENOENT;
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dev = inode->i_zone[0];
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if (!S_ISBLK(inode->i_mode)) {
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iput(inode);
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return -ENOTBLK;
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}
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iput(inode);
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if (dev==ROOT_DEV)
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return -EBUSY;
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if (!(sb=get_super(dev)) || !(sb->s_imount))
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return -ENOENT;
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if (!sb->s_imount->i_mount)
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printk("Mounted inode has i_mount=0\n");
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for (inode=inode_table+0 ; inode<inode_table+NR_INODE ; inode++)
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if (inode->i_dev==dev && inode->i_count)
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return -EBUSY;
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sb->s_imount->i_mount=0;
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iput(sb->s_imount);
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sb->s_imount = NULL;
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iput(sb->s_isup);
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sb->s_isup = NULL;
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put_super(dev);
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sync_dev(dev);
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return 0;
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}
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int sys_mount(char * dev_name, char * dir_name, int rw_flag)
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{
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struct m_inode * dev_i, * dir_i;
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struct super_block * sb;
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int dev;
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if (!(dev_i=namei(dev_name)))
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return -ENOENT;
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dev = dev_i->i_zone[0];
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if (!S_ISBLK(dev_i->i_mode)) {
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iput(dev_i);
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return -EPERM;
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}
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iput(dev_i);
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if (!(dir_i=namei(dir_name)))
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return -ENOENT;
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if (dir_i->i_count != 1 || dir_i->i_num == ROOT_INO) {
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iput(dir_i);
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return -EBUSY;
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}
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if (!S_ISDIR(dir_i->i_mode)) {
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iput(dir_i);
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return -EPERM;
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}
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if (!(sb=read_super(dev))) {
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iput(dir_i);
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return -EBUSY;
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}
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if (sb->s_imount) {
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iput(dir_i);
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return -EBUSY;
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}
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if (dir_i->i_mount) {
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iput(dir_i);
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return -EPERM;
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}
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sb->s_imount=dir_i;
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dir_i->i_mount=1;
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dir_i->i_dirt=1; /* NOTE! we don't iput(dir_i) */
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return 0; /* we do that in umount */
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}
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void mount_root(void)
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{
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int i,free;
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struct super_block * p;
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struct m_inode * mi;
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if (32 != sizeof (struct d_inode))
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panic("bad i-node size");
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for(i=0;i<NR_FILE;i++)
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file_table[i].f_count=0;
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if (MAJOR(ROOT_DEV) == 2) {
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printk("Insert root floppy and press ENTER");
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wait_for_keypress();
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}
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for(p = &super_block[0] ; p < &super_block[NR_SUPER] ; p++) {
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p->s_dev = 0;
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p->s_lock = 0;
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p->s_wait = NULL;
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}
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if (!(p=read_super(ROOT_DEV)))
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panic("Unable to mount root");
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if (!(mi=iget(ROOT_DEV,ROOT_INO)))
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panic("Unable to read root i-node");
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mi->i_count += 3 ; /* NOTE! it is logically used 4 times, not 1 */
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p->s_isup = p->s_imount = mi;
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current->pwd = mi;
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current->root = mi;
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free=0;
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i=p->s_nzones;
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while (-- i >= 0)
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if (!set_bit(i&8191,p->s_zmap[i>>13]->b_data))
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free++;
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printk("%d/%d free blocks\n\r",free,p->s_nzones);
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free=0;
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i=p->s_ninodes+1;
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while (-- i >= 0)
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if (!set_bit(i&8191,p->s_imap[i>>13]->b_data))
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free++;
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printk("%d/%d free inodes\n\r",free,p->s_ninodes);
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}
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