block bitmap
balloc
This commit is contained in:
kaashoek
parent
0e84a0ec6e
commit
241113985f
74
fs.c
74
fs.c
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@ -16,6 +16,43 @@ struct spinlock inode_table_lock = { "inode_table" };
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uint rootdev = 1;
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static uint
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balloc(uint dev)
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{
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int b;
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struct buf *bp;
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struct superblock *sb;
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int bi;
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int size;
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int ninodes;
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uchar m;
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bp = bread(dev, 1);
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sb = (struct superblock *) bp->data;
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size = sb->size;
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ninodes = sb->ninodes;
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for (b = 0; b < size; b++) {
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if (b % BPB == 0) {
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brelse(bp);
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bp = bread(dev, BBLOCK(b, ninodes));
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}
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bi = b % BPB;
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m = 0x1 << (bi % 8);
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if ((bp->data[bi/8] & m) == 0) { // is block free?
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break;
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}
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}
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if (b >= size)
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panic("balloc: out of blocks\n");
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cprintf ("balloc: allocate block %d\n", b);
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bp->data[bi/8] |= 0x1 << (bi % 8);
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bwrite (dev, bp, BBLOCK(b, ninodes)); // mark it allocated on disk
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return b;
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}
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// returns an inode with busy set and incremented reference count.
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struct inode *
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iget(uint dev, uint inum)
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@ -51,7 +88,7 @@ iget(uint dev, uint inum)
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release(&inode_table_lock);
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bp = bread(dev, inum / IPB + 2);
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bp = bread(dev, IBLOCK(inum));
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dip = &((struct dinode *)(bp->data))[inum % IPB];
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nip->type = dip->type;
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nip->major = dip->major;
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@ -76,12 +113,12 @@ ialloc(uint dev, short type)
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struct buf *bp;
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bp = bread(dev, 1);
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sb = (struct superblock *) bp;
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sb = (struct superblock *) bp->data;
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ninodes = sb->ninodes;
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brelse(bp);
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for (inum = 1; inum < ninodes; inum++) { // loop over inode blocks
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bp = bread(dev, inum / IPB + 2);
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bp = bread(dev, IBLOCK(inum));
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dip = &((struct dinode *)(bp->data))[inum % IPB];
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if (dip->type == 0) { // a free inode
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break;
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@ -90,13 +127,12 @@ ialloc(uint dev, short type)
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}
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if (inum >= ninodes) {
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cprintf ("ialloc: no inodes left\n");
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return 0;
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panic ("ialloc: no inodes left\n");
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}
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cprintf ("ialloc: %d\n", inum);
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dip->type = type;
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bwrite (dev, bp, inum / IPB + 2); // mark it allocated on the disk
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bwrite (dev, bp, IBLOCK(inum)); // mark it allocated on the disk
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brelse(bp);
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ip = iget (dev, inum);
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return ip;
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@ -108,14 +144,14 @@ iupdate (struct inode *ip)
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struct buf *bp;
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struct dinode *dip;
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bp = bread(ip->dev, ip->inum / IPB + 2);
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bp = bread(ip->dev, IBLOCK(ip->inum));
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dip = &((struct dinode *)(bp->data))[ip->inum % IPB];
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dip->type = ip->type;
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dip->major = ip->major;
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dip->minor = ip->minor;
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dip->nlink = ip->nlink;
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dip->size = ip->size;
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bwrite (ip->dev, bp, ip->inum / IPB + 2); // mark it allocated on the disk
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bwrite (ip->dev, bp, IBLOCK(ip->inum)); // mark it allocated on the disk
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brelse(bp);
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}
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@ -203,10 +239,10 @@ readi(struct inode *ip, void *xdst, uint off, uint n)
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struct buf *bp;
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while(n > 0 && off < ip->size){
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bp = bread(ip->dev, bmap(ip, off / 512));
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bp = bread(ip->dev, bmap(ip, off / BSIZE));
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n1 = min(n, ip->size - off);
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n1 = min(n1, 512 - (off % 512));
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memmove(dst, bp->data + (off % 512), n1);
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n1 = min(n1, BSIZE - (off % BSIZE));
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memmove(dst, bp->data + (off % BSIZE), n1);
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n -= n1;
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off += n1;
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dst += n1;
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@ -241,10 +277,10 @@ namei(char *path)
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return 0;
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}
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for(off = 0; off < dp->size; off += 512){
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bp = bread(dp->dev, bmap(dp, off / 512));
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for(off = 0; off < dp->size; off += BSIZE){
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bp = bread(dp->dev, bmap(dp, off / BSIZE));
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for(ep = (struct dirent *) bp->data;
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ep < (struct dirent *) (bp->data + 512);
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ep < (struct dirent *) (bp->data + BSIZE);
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ep++){
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if(ep->inum == 0)
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continue;
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@ -288,10 +324,10 @@ mknod(struct inode *dp, char *cp, short type, short major, short minor)
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ip->major = major;
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ip->minor = minor;
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for(off = 0; off < dp->size; off += 512) {
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bp = bread(dp->dev, bmap(dp, off / 512));
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for(off = 0; off < dp->size; off += BSIZE) {
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bp = bread(dp->dev, bmap(dp, off / BSIZE));
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for(ep = (struct dirent *) bp->data;
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ep < (struct dirent *) (bp->data + 512);
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ep < (struct dirent *) (bp->data + BSIZE);
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ep++){
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if(ep->inum == 0) {
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goto found;
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@ -304,7 +340,7 @@ mknod(struct inode *dp, char *cp, short type, short major, short minor)
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found:
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ep->inum = ip->inum;
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for(i = 0; i < DIRSIZ && cp[i]; i++) ep->name[i] = cp[i];
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bwrite (dp->dev, bp, bmap(dp, off/512)); // write directory
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bwrite (dp->dev, bp, bmap(dp, off/BSIZE)); // write directory
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brelse(bp);
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iupdate (ip);
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return ip;
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17
fs.h
17
fs.h
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@ -1,15 +1,16 @@
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// on-disk file system format
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// second sector
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#define BSIZE 512 // block size
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// sector 1 (2nd sector)
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struct superblock{
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int nblocks;
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int ninodes;
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uint size;
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uint nblocks;
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uint ninodes;
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};
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#define NDIRECT 13
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// inodes start at the third sector
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// and blocks start at (ninodes * sizeof(dinode) + 511) / 512
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struct dinode {
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short type;
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short major;
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@ -23,7 +24,11 @@ struct dinode {
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#define T_FILE 2
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#define T_DEV 3
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#define IPB (512 / sizeof(struct dinode))
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// sector 0 is unused, sector 1 is superblock, inodes start at sector 2
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#define IPB (BSIZE / sizeof(struct dinode))
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#define IBLOCK(inum) (inum / IPB + 2) // start of inode
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#define BPB (BSIZE*8)
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#define BBLOCK(b,ninodes) (b/BPB + (ninodes/IPB) + 3) // start of bitmap
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#define DIRSIZ 14
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42
mkfs.c
42
mkfs.c
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@ -8,15 +8,19 @@
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#include "param.h"
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#include "fs.h"
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int nblocks = 1009;
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int nblocks = 1008;
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int ninodes = 100;
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int size = 1024;
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int fsfd;
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struct superblock sb;
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char zeroes[512];
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uint freeblock;
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uint usedblocks;
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uint bitblocks;
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uint freeinode = 1;
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void balloc(int);
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void wsect(uint, void *);
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void winode(uint, struct dinode *);
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void rsect(uint sec, void *buf);
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@ -67,12 +71,20 @@ main(int argc, char *argv[])
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exit(1);
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}
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sb.nblocks = xint(nblocks); // so whole disk is 1024 sectors
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sb.size = xint(size);
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sb.nblocks = xint(nblocks); // so whole disk is size sectors
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sb.ninodes = xint(ninodes);
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freeblock = ninodes / IPB + 2;
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bitblocks = sb.size/(512*8) + 1;
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usedblocks = ninodes / IPB + 3 + bitblocks;
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freeblock = usedblocks;
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for(i = 0; i < nblocks + (ninodes / IPB) + 3; i++)
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printf ("used %d (bit %d ninode %d) free %d total %d\n", usedblocks,
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bitblocks, ninodes/IPB + 1, freeblock, nblocks+usedblocks);
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assert (nblocks + usedblocks == size);
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for(i = 0; i < nblocks + usedblocks; i++)
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wsect(i, zeroes);
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wsect(1, &sb);
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@ -110,6 +122,8 @@ main(int argc, char *argv[])
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close(fd);
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}
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balloc(usedblocks);
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exit(0);
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}
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@ -186,6 +200,22 @@ ialloc(ushort type)
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return inum;
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}
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void
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balloc(int used)
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{
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uchar buf[512];
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int i;
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printf("balloc: first %d blocks have been allocated\n", used);
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assert (used < 512);
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bzero(buf, 512);
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for (i = 0; i < used; i++) {
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buf[i/8] = buf[i/8] | (0x1 << (i%8));
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}
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printf("balloc: write bitmap block at sector %d\n", ninodes/IPB + 3);
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wsect(ninodes / IPB + 3, buf);
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}
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#define min(a, b) ((a) < (b) ? (a) : (b))
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void
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@ -202,8 +232,10 @@ iappend(uint inum, void *xp, int n)
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while(n > 0){
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fbn = off / 512;
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assert(fbn < NDIRECT);
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if(din.addrs[fbn] == 0)
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if(din.addrs[fbn] == 0) {
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din.addrs[fbn] = xint(freeblock++);
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usedblocks++;
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}
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n1 = min(n, (fbn + 1) * 512 - off);
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rsect(xint(din.addrs[fbn]), buf);
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bcopy(p, buf + off - (fbn * 512), n1);
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