diff options
| -rw-r--r-- | fs.c | 74 | ||||
| -rw-r--r-- | fs.h | 17 | ||||
| -rw-r--r-- | mkfs.c | 42 |
3 files changed, 103 insertions, 30 deletions
@@ -16,6 +16,43 @@ struct spinlock inode_table_lock = { "inode_table" }; uint rootdev = 1; +static uint +balloc(uint dev) +{ + int b; + struct buf *bp; + struct superblock *sb; + int bi; + int size; + int ninodes; + uchar m; + + bp = bread(dev, 1); + sb = (struct superblock *) bp->data; + size = sb->size; + ninodes = sb->ninodes; + + for (b = 0; b < size; b++) { + if (b % BPB == 0) { + brelse(bp); + bp = bread(dev, BBLOCK(b, ninodes)); + } + bi = b % BPB; + m = 0x1 << (bi % 8); + if ((bp->data[bi/8] & m) == 0) { // is block free? + break; + } + } + if (b >= size) + panic("balloc: out of blocks\n"); + + cprintf ("balloc: allocate block %d\n", b); + bp->data[bi/8] |= 0x1 << (bi % 8); + bwrite (dev, bp, BBLOCK(b, ninodes)); // mark it allocated on disk + return b; +} + + // returns an inode with busy set and incremented reference count. struct inode * iget(uint dev, uint inum) @@ -51,7 +88,7 @@ iget(uint dev, uint inum) release(&inode_table_lock); - bp = bread(dev, inum / IPB + 2); + bp = bread(dev, IBLOCK(inum)); dip = &((struct dinode *)(bp->data))[inum % IPB]; nip->type = dip->type; nip->major = dip->major; @@ -76,12 +113,12 @@ ialloc(uint dev, short type) struct buf *bp; bp = bread(dev, 1); - sb = (struct superblock *) bp; + sb = (struct superblock *) bp->data; ninodes = sb->ninodes; brelse(bp); - + for (inum = 1; inum < ninodes; inum++) { // loop over inode blocks - bp = bread(dev, inum / IPB + 2); + bp = bread(dev, IBLOCK(inum)); dip = &((struct dinode *)(bp->data))[inum % IPB]; if (dip->type == 0) { // a free inode break; @@ -90,13 +127,12 @@ ialloc(uint dev, short type) } if (inum >= ninodes) { - cprintf ("ialloc: no inodes left\n"); - return 0; + panic ("ialloc: no inodes left\n"); } cprintf ("ialloc: %d\n", inum); dip->type = type; - bwrite (dev, bp, inum / IPB + 2); // mark it allocated on the disk + bwrite (dev, bp, IBLOCK(inum)); // mark it allocated on the disk brelse(bp); ip = iget (dev, inum); return ip; @@ -108,14 +144,14 @@ iupdate (struct inode *ip) struct buf *bp; struct dinode *dip; - bp = bread(ip->dev, ip->inum / IPB + 2); + bp = bread(ip->dev, IBLOCK(ip->inum)); dip = &((struct dinode *)(bp->data))[ip->inum % IPB]; dip->type = ip->type; dip->major = ip->major; dip->minor = ip->minor; dip->nlink = ip->nlink; dip->size = ip->size; - bwrite (ip->dev, bp, ip->inum / IPB + 2); // mark it allocated on the disk + bwrite (ip->dev, bp, IBLOCK(ip->inum)); // mark it allocated on the disk brelse(bp); } @@ -203,10 +239,10 @@ readi(struct inode *ip, void *xdst, uint off, uint n) struct buf *bp; while(n > 0 && off < ip->size){ - bp = bread(ip->dev, bmap(ip, off / 512)); + bp = bread(ip->dev, bmap(ip, off / BSIZE)); n1 = min(n, ip->size - off); - n1 = min(n1, 512 - (off % 512)); - memmove(dst, bp->data + (off % 512), n1); + n1 = min(n1, BSIZE - (off % BSIZE)); + memmove(dst, bp->data + (off % BSIZE), n1); n -= n1; off += n1; dst += n1; @@ -241,10 +277,10 @@ namei(char *path) return 0; } - for(off = 0; off < dp->size; off += 512){ - bp = bread(dp->dev, bmap(dp, off / 512)); + for(off = 0; off < dp->size; off += BSIZE){ + bp = bread(dp->dev, bmap(dp, off / BSIZE)); for(ep = (struct dirent *) bp->data; - ep < (struct dirent *) (bp->data + 512); + ep < (struct dirent *) (bp->data + BSIZE); ep++){ if(ep->inum == 0) continue; @@ -288,10 +324,10 @@ mknod(struct inode *dp, char *cp, short type, short major, short minor) ip->major = major; ip->minor = minor; - for(off = 0; off < dp->size; off += 512) { - bp = bread(dp->dev, bmap(dp, off / 512)); + for(off = 0; off < dp->size; off += BSIZE) { + bp = bread(dp->dev, bmap(dp, off / BSIZE)); for(ep = (struct dirent *) bp->data; - ep < (struct dirent *) (bp->data + 512); + ep < (struct dirent *) (bp->data + BSIZE); ep++){ if(ep->inum == 0) { goto found; @@ -304,7 +340,7 @@ mknod(struct inode *dp, char *cp, short type, short major, short minor) found: ep->inum = ip->inum; for(i = 0; i < DIRSIZ && cp[i]; i++) ep->name[i] = cp[i]; - bwrite (dp->dev, bp, bmap(dp, off/512)); // write directory + bwrite (dp->dev, bp, bmap(dp, off/BSIZE)); // write directory brelse(bp); iupdate (ip); return ip; @@ -1,15 +1,16 @@ // on-disk file system format -// second sector +#define BSIZE 512 // block size + +// sector 1 (2nd sector) struct superblock{ - int nblocks; - int ninodes; + uint size; + uint nblocks; + uint ninodes; }; #define NDIRECT 13 -// inodes start at the third sector -// and blocks start at (ninodes * sizeof(dinode) + 511) / 512 struct dinode { short type; short major; @@ -23,7 +24,11 @@ struct dinode { #define T_FILE 2 #define T_DEV 3 -#define IPB (512 / sizeof(struct dinode)) +// sector 0 is unused, sector 1 is superblock, inodes start at sector 2 +#define IPB (BSIZE / sizeof(struct dinode)) +#define IBLOCK(inum) (inum / IPB + 2) // start of inode +#define BPB (BSIZE*8) +#define BBLOCK(b,ninodes) (b/BPB + (ninodes/IPB) + 3) // start of bitmap #define DIRSIZ 14 @@ -8,15 +8,19 @@ #include "param.h" #include "fs.h" -int nblocks = 1009; +int nblocks = 1008; int ninodes = 100; +int size = 1024; int fsfd; struct superblock sb; char zeroes[512]; uint freeblock; +uint usedblocks; +uint bitblocks; uint freeinode = 1; +void balloc(int); void wsect(uint, void *); void winode(uint, struct dinode *); void rsect(uint sec, void *buf); @@ -67,12 +71,20 @@ main(int argc, char *argv[]) exit(1); } - sb.nblocks = xint(nblocks); // so whole disk is 1024 sectors + sb.size = xint(size); + sb.nblocks = xint(nblocks); // so whole disk is size sectors sb.ninodes = xint(ninodes); - freeblock = ninodes / IPB + 2; + bitblocks = sb.size/(512*8) + 1; + usedblocks = ninodes / IPB + 3 + bitblocks; + freeblock = usedblocks; - for(i = 0; i < nblocks + (ninodes / IPB) + 3; i++) + printf ("used %d (bit %d ninode %d) free %d total %d\n", usedblocks, + bitblocks, ninodes/IPB + 1, freeblock, nblocks+usedblocks); + + assert (nblocks + usedblocks == size); + + for(i = 0; i < nblocks + usedblocks; i++) wsect(i, zeroes); wsect(1, &sb); @@ -110,6 +122,8 @@ main(int argc, char *argv[]) close(fd); } + balloc(usedblocks); + exit(0); } @@ -186,6 +200,22 @@ ialloc(ushort type) return inum; } +void +balloc(int used) +{ + uchar buf[512]; + int i; + + printf("balloc: first %d blocks have been allocated\n", used); + assert (used < 512); + bzero(buf, 512); + for (i = 0; i < used; i++) { + buf[i/8] = buf[i/8] | (0x1 << (i%8)); + } + printf("balloc: write bitmap block at sector %d\n", ninodes/IPB + 3); + wsect(ninodes / IPB + 3, buf); +} + #define min(a, b) ((a) < (b) ? (a) : (b)) void @@ -202,8 +232,10 @@ iappend(uint inum, void *xp, int n) while(n > 0){ fbn = off / 512; assert(fbn < NDIRECT); - if(din.addrs[fbn] == 0) + if(din.addrs[fbn] == 0) { din.addrs[fbn] = xint(freeblock++); + usedblocks++; + } n1 = min(n, (fbn + 1) * 512 - off); rsect(xint(din.addrs[fbn]), buf); bcopy(p, buf + off - (fbn * 512), n1); |