159 lines
3.9 KiB
C
159 lines
3.9 KiB
C
/* bitmap.c contains the code that handles the inode and block bitmaps */
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#include <string.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#define clear_block(addr) \
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__asm__("cld\n\t" \
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"rep\n\t" \
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"stosl" \
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::"a" (0),"c" (BLOCK_SIZE/4),"D" ((long) (addr)):"cx","di")
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#define set_bit(nr,addr) ({\
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register int res __asm__("ax"); \
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__asm__("btsl %2,%3\n\tsetb %%al":"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
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res;})
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#define clear_bit(nr,addr) ({\
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register int res __asm__("ax"); \
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__asm__("btrl %2,%3\n\tsetnb %%al":"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
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res;})
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#define find_first_zero(addr) ({ \
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int __res; \
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__asm__("cld\n" \
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"1:\tlodsl\n\t" \
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"notl %%eax\n\t" \
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"bsfl %%eax,%%edx\n\t" \
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"je 2f\n\t" \
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"addl %%edx,%%ecx\n\t" \
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"jmp 3f\n" \
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"2:\taddl $32,%%ecx\n\t" \
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"cmpl $8192,%%ecx\n\t" \
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"jl 1b\n" \
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"3:" \
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:"=c" (__res):"c" (0),"S" (addr):"ax","dx","si"); \
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__res;})
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void free_block(int dev, int block)
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{
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struct super_block * sb;
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struct buffer_head * bh;
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if (!(sb = get_super(dev)))
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panic("trying to free block on nonexistent device");
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if (block < sb->s_firstdatazone || block >= sb->s_nzones)
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panic("trying to free block not in datazone");
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bh = get_hash_table(dev,block);
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if (bh) {
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if (bh->b_count != 1) {
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printk("trying to free block (%04x:%d), count=%d\n",
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dev,block,bh->b_count);
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return;
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}
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bh->b_dirt=0;
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bh->b_uptodate=0;
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brelse(bh);
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}
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block -= sb->s_firstdatazone - 1 ;
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if (clear_bit(block&8191,sb->s_zmap[block/8192]->b_data)) {
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printk("block (%04x:%d) ",dev,block+sb->s_firstdatazone-1);
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panic("free_block: bit already cleared");
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}
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sb->s_zmap[block/8192]->b_dirt = 1;
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}
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int new_block(int dev)
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{
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struct buffer_head * bh;
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struct super_block * sb;
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int i,j;
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if (!(sb = get_super(dev)))
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panic("trying to get new block from nonexistant device");
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j = 8192;
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for (i=0 ; i<8 ; i++)
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if (bh=sb->s_zmap[i])
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if ((j=find_first_zero(bh->b_data))<8192)
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break;
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if (i>=8 || !bh || j>=8192)
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return 0;
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if (set_bit(j,bh->b_data))
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panic("new_block: bit already set");
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bh->b_dirt = 1;
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j += i*8192 + sb->s_firstdatazone-1;
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if (j >= sb->s_nzones)
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return 0;
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if (!(bh=getblk(dev,j)))
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panic("new_block: cannot get block");
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if (bh->b_count != 1)
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panic("new block: count is != 1");
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clear_block(bh->b_data);
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bh->b_uptodate = 1;
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bh->b_dirt = 1;
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brelse(bh);
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return j;
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}
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void free_inode(struct m_inode * inode)
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{
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struct super_block * sb;
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struct buffer_head * bh;
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if (!inode)
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return;
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if (!inode->i_dev) {
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memset(inode,0,sizeof(*inode));
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return;
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}
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if (inode->i_count>1) {
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printk("trying to free inode with count=%d\n",inode->i_count);
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panic("free_inode");
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}
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if (inode->i_nlinks)
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panic("trying to free inode with links");
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if (!(sb = get_super(inode->i_dev)))
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panic("trying to free inode on nonexistent device");
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if (inode->i_num < 1 || inode->i_num > sb->s_ninodes)
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panic("trying to free inode 0 or nonexistant inode");
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if (!(bh=sb->s_imap[inode->i_num>>13]))
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panic("nonexistent imap in superblock");
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if (clear_bit(inode->i_num&8191,bh->b_data))
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panic("free_inode: bit already cleared");
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bh->b_dirt = 1;
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memset(inode,0,sizeof(*inode));
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}
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struct m_inode * new_inode(int dev)
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{
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struct m_inode * inode;
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struct super_block * sb;
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struct buffer_head * bh;
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int i,j;
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if (!(inode=get_empty_inode()))
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return NULL;
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if (!(sb = get_super(dev)))
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panic("new_inode with unknown device");
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j = 8192;
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for (i=0 ; i<8 ; i++)
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if (bh=sb->s_imap[i])
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if ((j=find_first_zero(bh->b_data))<8192)
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break;
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if (!bh || j >= 8192 || j+i*8192 > sb->s_ninodes) {
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iput(inode);
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return NULL;
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}
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if (set_bit(j,bh->b_data))
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panic("new_inode: bit already set");
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bh->b_dirt = 1;
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inode->i_count=1;
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inode->i_nlinks=1;
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inode->i_dev=dev;
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inode->i_dirt=1;
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inode->i_num = j + i*8192;
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inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
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return inode;
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}
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