1 files changed, 168 insertions, 0 deletions

diff --git a/src/fs/bitmap.c b/src/fs/bitmap.c
new file mode 100644
index 0000000..fb0741d
--- /dev/null
+++ b/src/fs/bitmap.c
@@ -0,0 +1,168 @@
+/*
+ *  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>
+
+#define clear_block(addr) \
+__asm__ __volatile__ ("cld\n\t" \
+        "rep\n\t" \
+        "stosl" \
+        ::"a" (0),"c" (BLOCK_SIZE/4),"D" ((long) (addr)))
+
+#define set_bit(nr,addr) ({\
+register int res ; \
+__asm__ __volatile__("btsl %2,%3\n\tsetb %%al": \
+"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
+res;})
+
+#define clear_bit(nr,addr) ({\
+register int res ; \
+__asm__ __volatile__("btrl %2,%3\n\tsetnb %%al": \
+"=a" (res):"0" (0),"r" (nr),"m" (*(addr))); \
+res;})
+
+#define find_first_zero(addr) ({ \
+int __res; \
+__asm__ __volatile__ ("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)); \
+__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))
+                printk("free_inode: bit already cleared.\n\r");
+        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_uid=current->euid;
+        inode->i_gid=current->egid;
+        inode->i_dirt=1;
+        inode->i_num = j + i*8192;
+        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+        return inode;
+}