diff options
Diffstat (limited to 'linux/fs/bitmap.c')
| -rw-r--r-- | linux/fs/bitmap.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/linux/fs/bitmap.c b/linux/fs/bitmap.c new file mode 100644 index 0000000..49bb81b --- /dev/null +++ b/linux/fs/bitmap.c @@ -0,0 +1,158 @@ +/* bitmap.c contains the code that handles the inode and block bitmaps */ +#include <string.h> + +#include <linux/sched.h> +#include <linux/kernel.h> + +#define clear_block(addr) \ +__asm__("cld\n\t" \ + "rep\n\t" \ + "stosl" \ + ::"a" (0),"c" (BLOCK_SIZE/4),"D" ((long) (addr)):"cx","di") + +#define set_bit(nr,addr) ({\ +register int res __asm__("ax"); \ +__asm__("btsl %2,%3\n\tsetb %%al":"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \ +res;}) + +#define clear_bit(nr,addr) ({\ +register int res __asm__("ax"); \ +__asm__("btrl %2,%3\n\tsetnb %%al":"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \ +res;}) + +#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;}) + +void free_block(int dev, int block) +{ + struct super_block * sb; + struct buffer_head * bh; + + if (!(sb = get_super(dev))) + panic("trying to free block on nonexistent device"); + if (block < sb->s_firstdatazone || block >= sb->s_nzones) + panic("trying to free block not in datazone"); + bh = get_hash_table(dev,block); + if (bh) { + if (bh->b_count != 1) { + printk("trying to free block (%04x:%d), count=%d\n", + dev,block,bh->b_count); + return; + } + bh->b_dirt=0; + bh->b_uptodate=0; + brelse(bh); + } + block -= sb->s_firstdatazone - 1 ; + if (clear_bit(block&8191,sb->s_zmap[block/8192]->b_data)) { + printk("block (%04x:%d) ",dev,block+sb->s_firstdatazone-1); + panic("free_block: bit already cleared"); + } + sb->s_zmap[block/8192]->b_dirt = 1; +} + +int new_block(int dev) +{ + struct buffer_head * bh; + struct super_block * sb; + int i,j; + + if (!(sb = get_super(dev))) + panic("trying to get new block from nonexistant device"); + j = 8192; + for (i=0 ; i<8 ; i++) + if (bh=sb->s_zmap[i]) + if ((j=find_first_zero(bh->b_data))<8192) + break; + if (i>=8 || !bh || j>=8192) + return 0; + if (set_bit(j,bh->b_data)) + panic("new_block: bit already set"); + bh->b_dirt = 1; + j += i*8192 + sb->s_firstdatazone-1; + if (j >= sb->s_nzones) + return 0; + if (!(bh=getblk(dev,j))) + panic("new_block: cannot get block"); + if (bh->b_count != 1) + panic("new block: count is != 1"); + clear_block(bh->b_data); + bh->b_uptodate = 1; + bh->b_dirt = 1; + brelse(bh); + return j; +} + +void free_inode(struct m_inode * inode) +{ + struct super_block * sb; + struct buffer_head * bh; + + if (!inode) + return; + if (!inode->i_dev) { + memset(inode,0,sizeof(*inode)); + return; + } + if (inode->i_count>1) { + printk("trying to free inode with count=%d\n",inode->i_count); + panic("free_inode"); + } + if (inode->i_nlinks) + panic("trying to free inode with links"); + if (!(sb = get_super(inode->i_dev))) + panic("trying to free inode on nonexistent device"); + if (inode->i_num < 1 || inode->i_num > sb->s_ninodes) + panic("trying to free inode 0 or nonexistant inode"); + if (!(bh=sb->s_imap[inode->i_num>>13])) + panic("nonexistent imap in superblock"); + if (clear_bit(inode->i_num&8191,bh->b_data)) + panic("free_inode: bit already cleared"); + bh->b_dirt = 1; + memset(inode,0,sizeof(*inode)); +} + +struct m_inode * new_inode(int dev) +{ + struct m_inode * inode; + struct super_block * sb; + struct buffer_head * bh; + int i,j; + + if (!(inode=get_empty_inode())) + return NULL; + if (!(sb = get_super(dev))) + panic("new_inode with unknown device"); + j = 8192; + for (i=0 ; i<8 ; i++) + if (bh=sb->s_imap[i]) + if ((j=find_first_zero(bh->b_data))<8192) + break; + if (!bh || j >= 8192 || j+i*8192 > sb->s_ninodes) { + iput(inode); + return NULL; + } + if (set_bit(j,bh->b_data)) + panic("new_inode: bit already set"); + bh->b_dirt = 1; + inode->i_count=1; + inode->i_nlinks=1; + inode->i_dev=dev; + inode->i_dirt=1; + inode->i_num = j + i*8192; + inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; + return inode; +} |