fs/ext/bitmap.c

/* */
This source file includes following definitions.
count_used
ext_free_block
ext_new_block
ext_count_free_blocks
ext_free_inode
ext_new_inode
ext_count_free_inodes
   1 /*
   2  *  linux/fs/ext/bitmap.c
   3  *
   4  *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
   5  *
   6  *  from
   7  *
   8  *  linux/fs/minix/bitmap.c
   9  *
  10  *  Copyright (C) 1991, 1992  Linus Torvalds
  11  */
  12 
  13 /* bitmap.c contains the code that handles the inode and block bitmaps */
  14 
  15 
  16 #include <linux/sched.h>
  17 #include <linux/ext_fs.h>
  18 #include <linux/kernel.h>
  19 #include <linux/string.h>
  20 
  21 #ifdef EXTFS_BITMAP
  22 
  23 #define clear_block(addr) \
  24 __asm__("cld\n\t" \
  25         "rep\n\t" \
  26         "stosl" \
  27         ::"a" (0),"c" (BLOCK_SIZE/4),"D" ((long) (addr)):"cx","di")
  28 
  29 #define set_bit(nr,addr) ({\
  30 char res; \
  31 __asm__ __volatile__("btsl %1,%2\n\tsetb %0": \
  32 "=q" (res):"r" (nr),"m" (*(addr))); \
  33 res;})
  34 
  35 #define clear_bit(nr,addr) ({\
  36 char res; \
  37 __asm__ __volatile__("btrl %1,%2\n\tsetnb %0": \
  38 "=q" (res):"r" (nr),"m" (*(addr))); \
  39 res;})
  40 
  41 #define find_first_zero(addr) ({ \
  42 int __res; \
  43 __asm__("cld\n" \
  44         "1:\tlodsl\n\t" \
  45         "notl %%eax\n\t" \
  46         "bsfl %%eax,%%edx\n\t" \
  47         "jne 2f\n\t" \
  48         "addl $32,%%ecx\n\t" \
  49         "cmpl $8192,%%ecx\n\t" \
  50         "jl 1b\n\t" \
  51         "xorl %%edx,%%edx\n" \
  52         "2:\taddl %%edx,%%ecx" \
  53         :"=c" (__res):"0" (0),"S" (addr):"ax","dx","si"); \
  54 __res;})
  55 
  56 static int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
  57 
  58 static unsigned long count_used(struct buffer_head *map[], unsigned numblocks,
     /*  */
  59         unsigned numbits)
  60 {
  61         unsigned i, j, end, sum = 0;
  62         struct buffer_head *bh;
  63   
  64         for (i=0; (i<numblocks) && numbits; i++) {
  65                 if (!(bh=map[i])) 
  66                         return(0);
  67                 if (numbits >= (8*BLOCK_SIZE)) { 
  68                         end = BLOCK_SIZE;
  69                         numbits -= 8*BLOCK_SIZE;
  70                 } else {
  71                         int tmp;
  72                         end = numbits >> 3;
  73                         numbits &= 0x7;
  74                         tmp = bh->b_data[end] & ((1<<numbits)-1);
  75                         sum += nibblemap[tmp&0xf] + nibblemap[(tmp>>4)&0xf];
  76                         numbits = 0;
  77                 }  
  78                 for (j=0; j<end; j++)
  79                         sum += nibblemap[bh->b_data[j] & 0xf] 
  80                                 + nibblemap[(bh->b_data[j]>>4)&0xf];
  81         }
  82         return(sum);
  83 }
  84 
  85 int ext_free_block(int dev, int block)
     /*  */
  86 {
  87         struct super_block * sb;
  88         struct buffer_head * bh;
  89         unsigned int bit,zone;
  90 
  91         if (!(sb = get_super(dev)))
  92                 panic("trying to free block on nonexistent device");
  93         if (block < sb->s_firstdatazone || block >= sb->s_nzones)
  94                 panic("trying to free block not in datazone");
  95         bh = get_hash_table(dev,block);
  96         if (bh) {
  97                 if (bh->b_count > 1) {
  98                         brelse(bh);
  99                         return 0;
 100                 }
 101                 bh->b_dirt=0;
 102                 bh->b_uptodate=0;
 103                 if (bh->b_count)
 104                         brelse(bh);
 105         }
 106         zone = block - sb->s_firstdatazone + 1;
 107         bit = zone & 8191;
 108         zone >>= 13;
 109         bh = sb->s_zmap[zone];
 110         if (clear_bit(bit,bh->b_data))
 111                 printk("free_block (%04x:%d): bit already cleared\n",dev,block);
 112         bh->b_dirt = 1;
 113         return 1;
 114 }
 115 
 116 int ext_new_block(int dev)
     /*  */
 117 {
 118         struct buffer_head * bh;
 119         struct super_block * sb;
 120         int i,j;
 121 
 122         if (!(sb = get_super(dev)))
 123                 panic("trying to get new block from nonexistant device");
 124         j = 8192;
 125         for (i=0 ; i<8 ; i++)
 126                 if (bh=sb->s_zmap[i])
 127                         if ((j=find_first_zero(bh->b_data))<8192)
 128                                 break;
 129         if (i>=8 || !bh || j>=8192)
 130                 return 0;
 131         if (set_bit(j,bh->b_data))
 132                 panic("new_block: bit already set");
 133         bh->b_dirt = 1;
 134         j += i*8192 + sb->s_firstdatazone-1;
 135         if (j >= sb->s_nzones)
 136                 return 0;
 137         if (!(bh=getblk(dev,j)))
 138                 panic("new_block: cannot get block");
 139         if (bh->b_count != 1)
 140                 panic("new block: count is != 1");
 141         clear_block(bh->b_data);
 142         bh->b_uptodate = 1;
 143         bh->b_dirt = 1;
 144         brelse(bh);
 145 #ifdef EXTFS_DEBUG
 146 printk("ext_new_block: allocating block %d\n", j);
 147 #endif
 148         return j;
 149 }
 150 
 151 unsigned long ext_count_free_blocks(struct super_block *sb)
     /*  */
 152 {
 153         return (sb->s_nzones - count_used(sb->s_zmap,sb->s_zmap_blocks,sb->s_nzones))
 154                  << sb->s_log_zone_size;
 155 }
 156 
 157 void ext_free_inode(struct inode * inode)
     /*  */
 158 {
 159         struct buffer_head * bh;
 160 
 161         if (!inode)
 162                 return;
 163         if (!inode->i_dev) {
 164                 memset(inode,0,sizeof(*inode));
 165                 return;
 166         }
 167         if (inode->i_count>1) {
 168                 printk("free_inode: inode has count=%d\n",inode->i_count);
 169                 return;
 170         }
 171         if (inode->i_nlink) {
 172                 printk("free_inode: inode has nlink=%d\n",inode->i_nlink);
 173                 return;
 174         }
 175         if (!inode->i_sb) {
 176                 printk("free_inode: inode on nonexistent device\n");
 177                 return;
 178         }
 179         if (inode->i_ino < 1 || inode->i_ino > inode->i_sb->s_ninodes) {
 180                 printk("free_inode: inode 0 or nonexistent inode\n");
 181                 return;
 182         }
 183         if (!(bh=inode->i_sb->s_imap[inode->i_ino>>13])) {
 184                 printk("free_inode: nonexistent imap in superblock\n");
 185                 return;
 186         }
 187         if (clear_bit(inode->i_ino&8191,bh->b_data))
 188                 printk("free_inode: bit already cleared.\n\r");
 189         bh->b_dirt = 1;
 190         memset(inode,0,sizeof(*inode));
 191 }
 192 
 193 struct inode * ext_new_inode(int dev)
     /*  */
 194 {
 195         struct inode * inode;
 196         struct buffer_head * bh;
 197         int i,j;
 198 
 199         if (!(inode=get_empty_inode()))
 200                 return NULL;
 201         if (!(inode->i_sb = get_super(dev))) {
 202                 printk("new_inode: unknown device\n");
 203                 iput(inode);
 204                 return NULL;
 205         }
 206         inode->i_flags = inode->i_sb->s_flags;
 207         j = 8192;
 208         for (i=0 ; i<8 ; i++)
 209                 if (bh=inode->i_sb->s_imap[i])
 210                         if ((j=find_first_zero(bh->b_data))<8192)
 211                                 break;
 212         if (!bh || j >= 8192 || j+i*8192 > inode->i_sb->s_ninodes) {
 213                 iput(inode);
 214                 return NULL;
 215         }
 216         if (set_bit(j,bh->b_data)) {    /* shouldn't happen */
 217                 printk("new_inode: bit already set");
 218                 iput(inode);
 219                 return NULL;
 220         }
 221         bh->b_dirt = 1;
 222         inode->i_count = 1;
 223         inode->i_nlink = 1;
 224         inode->i_dev = dev;
 225         inode->i_uid = current->euid;
 226         inode->i_gid = current->egid;
 227         inode->i_dirt = 1;
 228         inode->i_ino = j + i*8192;
 229         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 230         inode->i_op = NULL;
 231 #ifdef EXTFS_DEBUG
 232         printk("ext_new_inode : allocating inode %d\n", inode->i_ino);
 233 #endif
 234         return inode;
 235 }
 236 
 237 unsigned long ext_count_free_inodes(struct super_block *sb)
     /*  */
 238 {
 239         return sb->s_ninodes - count_used(sb->s_imap,sb->s_imap_blocks,sb->s_ninodes);
 240 }
 241 
 242 #endif
/* */
root/fs/ext/bitmap.c

DEFINITIONS
