fs/minix/bitmap.c

/* */
This source file includes following definitions.
count_used
minix_free_block
minix_new_block
minix_count_free_blocks
minix_free_inode
minix_new_inode
minix_count_free_inodes
   1 /*
   2  *  linux/fs/minix/bitmap.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /* bitmap.c contains the code that handles the inode and block bitmaps */
   8 
   9 #include <linux/sched.h>
  10 #include <linux/minix_fs.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 
  14 #define clear_block(addr) \
  15 __asm__("cld\n\t" \
  16         "rep\n\t" \
  17         "stosl" \
  18         ::"a" (0),"c" (BLOCK_SIZE/4),"D" ((long) (addr)):"cx","di")
  19 
  20 #define set_bit(nr,addr) ({\
  21 char res; \
  22 __asm__ __volatile__("btsl %1,%2\n\tsetb %0": \
  23 "=q" (res):"r" (nr),"m" (*(addr))); \
  24 res;})
  25 
  26 #define clear_bit(nr,addr) ({\
  27 char res; \
  28 __asm__ __volatile__("btrl %1,%2\n\tsetnb %0": \
  29 "=q" (res):"r" (nr),"m" (*(addr))); \
  30 res;})
  31 
  32 #define find_first_zero(addr) ({ \
  33 int __res; \
  34 __asm__("cld\n" \
  35         "1:\tlodsl\n\t" \
  36         "notl %%eax\n\t" \
  37         "bsfl %%eax,%%edx\n\t" \
  38         "jne 2f\n\t" \
  39         "addl $32,%%ecx\n\t" \
  40         "cmpl $8192,%%ecx\n\t" \
  41         "jl 1b\n\t" \
  42         "xorl %%edx,%%edx\n" \
  43         "2:\taddl %%edx,%%ecx" \
  44         :"=c" (__res):"0" (0),"S" (addr):"ax","dx","si"); \
  45 __res;})
  46 
  47 static int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
  48 
  49 static unsigned long count_used(struct buffer_head *map[], unsigned numblocks,
     /*  */
  50         unsigned numbits)
  51 {
  52         unsigned i, j, end, sum = 0;
  53         struct buffer_head *bh;
  54   
  55         for (i=0; (i<numblocks) && numbits; i++) {
  56                 if (!(bh=map[i])) 
  57                         return(0);
  58                 if (numbits >= (8*BLOCK_SIZE)) { 
  59                         end = BLOCK_SIZE;
  60                         numbits -= 8*BLOCK_SIZE;
  61                 } else {
  62                         int tmp;
  63                         end = numbits >> 3;
  64                         numbits &= 0x7;
  65                         tmp = bh->b_data[end] & ((1<<numbits)-1);
  66                         sum += nibblemap[tmp&0xf] + nibblemap[(tmp>>4)&0xf];
  67                         numbits = 0;
  68                 }  
  69                 for (j=0; j<end; j++)
  70                         sum += nibblemap[bh->b_data[j] & 0xf] 
  71                                 + nibblemap[(bh->b_data[j]>>4)&0xf];
  72         }
  73         return(sum);
  74 }
  75 
  76 void minix_free_block(struct super_block * sb, int block)
     /*  */
  77 {
  78         struct buffer_head * bh;
  79         unsigned int bit,zone;
  80 
  81         if (!sb) {
  82                 printk("trying to free block on nonexistent device\n");
  83                 return;
  84         }
  85         if (block < sb->u.minix_sb.s_firstdatazone ||
  86             block >= sb->u.minix_sb.s_nzones) {
  87                 printk("trying to free block not in datazone\n");
  88                 return;
  89         }
  90         bh = get_hash_table(sb->s_dev,block,BLOCK_SIZE);
  91         if (bh)
  92                 bh->b_dirt=0;
  93         brelse(bh);
  94         zone = block - sb->u.minix_sb.s_firstdatazone + 1;
  95         bit = zone & 8191;
  96         zone >>= 13;
  97         bh = sb->u.minix_sb.s_zmap[zone];
  98         if (!bh) {
  99                 printk("minix_free_block: nonexistent bitmap buffer\n");
 100                 return;
 101         }
 102         if (clear_bit(bit,bh->b_data))
 103                 printk("free_block (%04x:%d): bit already cleared\n",sb->s_dev,block);
 104         bh->b_dirt = 1;
 105         return;
 106 }
 107 
 108 int minix_new_block(struct super_block * sb)
     /*  */
 109 {
 110         struct buffer_head * bh;
 111         int i,j;
 112 
 113         if (!sb) {
 114                 printk("trying to get new block from nonexistant device\n");
 115                 return 0;
 116         }
 117 repeat:
 118         j = 8192;
 119         for (i=0 ; i<8 ; i++)
 120                 if (bh=sb->u.minix_sb.s_zmap[i])
 121                         if ((j=find_first_zero(bh->b_data))<8192)
 122                                 break;
 123         if (i>=8 || !bh || j>=8192)
 124                 return 0;
 125         if (set_bit(j,bh->b_data)) {
 126                 printk("new_block: bit already set");
 127                 goto repeat;
 128         }
 129         bh->b_dirt = 1;
 130         j += i*8192 + sb->u.minix_sb.s_firstdatazone-1;
 131         if (j >= sb->u.minix_sb.s_nzones)
 132                 return 0;
 133         if (!(bh = getblk(sb->s_dev,j,BLOCK_SIZE))) {
 134                 printk("new_block: cannot get block");
 135                 return 0;
 136         }
 137         if (bh->b_count != 1) {
 138                 printk("new block: count is != 1");
 139                 return 0;
 140         }
 141         clear_block(bh->b_data);
 142         bh->b_uptodate = 1;
 143         bh->b_dirt = 1;
 144         brelse(bh);
 145         return j;
 146 }
 147 
 148 unsigned long minix_count_free_blocks(struct super_block *sb)
     /*  */
 149 {
 150         return (sb->u.minix_sb.s_nzones - count_used(sb->u.minix_sb.s_zmap,sb->u.minix_sb.s_zmap_blocks,sb->u.minix_sb.s_nzones))
 151                  << sb->u.minix_sb.s_log_zone_size;
 152 }
 153 
 154 void minix_free_inode(struct inode * inode)
     /*  */
 155 {
 156         struct buffer_head * bh;
 157 
 158         if (!inode)
 159                 return;
 160         if (!inode->i_dev) {
 161                 memset(inode,0,sizeof(*inode));
 162                 return;
 163         }
 164         if (inode->i_count>1) {
 165                 printk("free_inode: inode has count=%d\n",inode->i_count);
 166                 return;
 167         }
 168         if (inode->i_nlink) {
 169                 printk("free_inode: inode has nlink=%d\n",inode->i_nlink);
 170                 return;
 171         }
 172         if (!inode->i_sb) {
 173                 printk("free_inode: inode on nonexistent device\n");
 174                 return;
 175         }
 176         if (inode->i_ino < 1 || inode->i_ino > inode->i_sb->u.minix_sb.s_ninodes) {
 177                 printk("free_inode: inode 0 or nonexistent inode\n");
 178                 return;
 179         }
 180         if (!(bh=inode->i_sb->u.minix_sb.s_imap[inode->i_ino>>13])) {
 181                 printk("free_inode: nonexistent imap in superblock\n");
 182                 return;
 183         }
 184         if (clear_bit(inode->i_ino&8191,bh->b_data))
 185                 printk("free_inode: bit already cleared.\n\r");
 186         bh->b_dirt = 1;
 187         memset(inode,0,sizeof(*inode));
 188 }
 189 
 190 struct inode * minix_new_inode(struct super_block * sb)
     /*  */
 191 {
 192         struct inode * inode;
 193         struct buffer_head * bh;
 194         int i,j;
 195 
 196         if (!sb || !(inode = get_empty_inode()))
 197                 return NULL;
 198         inode->i_sb = sb;
 199         inode->i_flags = inode->i_sb->s_flags;
 200         j = 8192;
 201         for (i=0 ; i<8 ; i++)
 202                 if (bh=inode->i_sb->u.minix_sb.s_imap[i])
 203                         if ((j=find_first_zero(bh->b_data))<8192)
 204                                 break;
 205         if (!bh || j >= 8192 || j+i*8192 > inode->i_sb->u.minix_sb.s_ninodes) {
 206                 iput(inode);
 207                 return NULL;
 208         }
 209         if (set_bit(j,bh->b_data)) {    /* shouldn't happen */
 210                 printk("new_inode: bit already set");
 211                 iput(inode);
 212                 return NULL;
 213         }
 214         bh->b_dirt = 1;
 215         inode->i_count = 1;
 216         inode->i_nlink = 1;
 217         inode->i_dev = sb->s_dev;
 218         inode->i_uid = current->euid;
 219         inode->i_gid = current->egid;
 220         inode->i_dirt = 1;
 221         inode->i_ino = j + i*8192;
 222         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 223         inode->i_op = NULL;
 224         inode->i_blocks = inode->i_blksize = 0;
 225         return inode;
 226 }
 227 
 228 unsigned long minix_count_free_inodes(struct super_block *sb)
     /*  */
 229 {
 230         return sb->u.minix_sb.s_ninodes - count_used(sb->u.minix_sb.s_imap,sb->u.minix_sb.s_imap_blocks,sb->u.minix_sb.s_ninodes);
 231 }
/* */
root/fs/minix/bitmap.c

DEFINITIONS
