linux 0.11 ÄÚºËѧϰ bitmap.c

/*
 *  linux/fs/bitmap.c
 *
 *  (C) 1991  Linus Torvalds
 */
/* bitmap.c contains the code that handles the inode and block bitmaps */
#include <string.h>
#include <linux/sched.h>
#include <linux/kernel.h> // һЩÄں˳£Óú¯ÊýµÄÔ­Ðζ¨Òå
/* ½«Ö¸¶¨µØÖ·(addr)´¦µÄÒ»¿éÄÚ´æÇåÁã */
#define clear_block(addr) \
__asm__("cld\n\t" \
"rep\n\t" \
"stosl" \
::"a" (0),"c" (BLOCK_SIZE/4),"D" ((long) (addr)):"cx","di")
/* ÖÃλָ¶¨µØÖ·¿ªÊ¼µÄµÚnr ¸öλƫÒÆ´¦µÄ±ÈÌØλ */
#define set_bit(nr,addr) ({\
register int res __asm__("ax"); \
__asm__ __volatile__("btsl %2,%3\n\tsetb %%al": \
"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
res;})
/* ¸´Î»Ö¸¶¨µØÖ·addr¿ªÊ¼µÄµÚnr λƫÒÆ´¦µÄ±ÈÌØλ */
#define clear_bit(nr,addr) ({\
register int res __asm__("ax"); \
__asm__ __volatile__("btrl %2,%3\n\tsetnb %%al": \
"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
res;})
/* ´Óaddr ¿ªÊ¼Ñ°ÕÒµÚ1 ¸ö0 Öµ±ÈÌØ룬²¢½«Æä¾àÀëaddr µÄ±ÈÌØλƫÒÆÖµ·µ»Ø */
#define find_first_zero(addr) ({ \
int __res; \
__asm__("cld\n" \
"1:\tlodsl\n\t" \
"notl %%eax\n\t" \
"bsfl %%eax,%%edx\n\t" \
"je 2f\n\t" \
"addl %%edx,%%ecx\n\t" \
"jmp 3f\n" \
"2:\taddl $32,%%ecx\n\t" \
"cmpl $8192,%%ecx\n\t" \
"jl 1b\n" \
"3:" \
:"=c" (__res):"c" (0),"S" (addr):"ax","dx","si"); \
__res;})
/* ¸´Î»Ö¸¶¨Âß¼­¿éblock £¨Ïà¶ÔÓÚ´ÅÅ̶øÑÔ£©µÄÂß¼­¿éλͼ±ÈÌØλ */
void free_block(int dev, int block)
{
struct super_block * sb;
struct buffer_head * bh;
if (!(sb = get_super(dev))) // È¡Ö¸¶¨É豸dev µÄ³¬¼¶¿é
panic("trying to free block on nonexistent device"); // É豸²»´æÔÚ
// ÈôÂß¼­¿éºÅСÓÚÊ׸öÂß¼­¿éºÅ»òÕß´óÓÚÉ豸ÉÏ×ÜÂß¼­¿éÊý
if (block < sb->s_firstdatazone || block >= sb->s_nzones)
panic("trying to free block not in datazone");
bh = get_hash_table(dev,block); // ´Óhash ±íÖÐÑ°ÕҸÿéÊý¾Ý
if (bh) // ºÏ·¨£¿ 
{
if (bh->b_count != 1) // Ö»Óиýø³ÌÕ¼¾Ýblock
{
printk("trying to free block (%04x:%d), count=%d\n",