Imbus/xv6-riscv-kernel
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Pick up where i left off in april:

Browse source 
- move log into metadata part of disk, so that marking
that the log's blocks are in use falls out for free
- superblock describes the whole disk (sizes and offets)
- sizes and offsets are computed in one place (mkfs) and
the rest of the code refers to the superblock for these values,
instead of recomputing them.
This commit is contained in:
Frans Kaashoek 2015-06-27 12:39:13 -04:00
parent de4af193c8
commit 8320d61be5
7 changed files with 47 additions and 45 deletions
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26
fs.c
View file

@ -22,6 +22,7 @@
#define min(a, b) ((a) < (b) ? (a) : (b))
static void itrunc(struct inode*);
struct superblock sb; // there should be one per dev, but we run with one dev
// Read the super block.
void
@ -54,12 +55,10 @@ balloc(uint dev)
{
int b, bi, m;
struct buf *bp;
struct superblock sb;
bp = 0;
readsb(dev, &sb);
for(b = 0; b < sb.size; b += BPB){
bp = bread(dev, BBLOCK(b, sb.ninodes));
bp = bread(dev, BBLOCK(b, sb));
for(bi = 0; bi < BPB && b + bi < sb.size; bi++){
m = 1 << (bi % 8);
if((bp->data[bi/8] & m) == 0){ // Is block free?
@ -80,11 +79,10 @@ static void
bfree(int dev, uint b)
{
struct buf *bp;
struct superblock sb;
int bi, m;
readsb(dev, &sb);
bp = bread(dev, BBLOCK(b, sb.ninodes));
bp = bread(dev, BBLOCK(b, sb));
bi = b % BPB;
m = 1 << (bi % 8);
if((bp->data[bi/8] & m) == 0)
@ -101,8 +99,8 @@ bfree(int dev, uint b)
// its size, the number of links referring to it, and the
// list of blocks holding the file's content.
//
// The inodes are laid out sequentially on disk immediately after
// the superblock. Each inode has a number, indicating its
// The inodes are laid out sequentially on disk at
// sb.startinode. Each inode has a number, indicating its
// position on the disk.
//
// The kernel keeps a cache of in-use inodes in memory
@ -162,9 +160,12 @@ struct {
} icache;
void
iinit(void)
iinit(int dev)
{
initlock(&icache.lock, "icache");
readsb(dev, &sb);
cprintf("sb: size %d nblocks %d ninodes %d nlog %d logstart %d inodestart %d bmap start %d\n", sb.size,
sb.nblocks, sb.ninodes, sb.nlog, sb.logstart, sb.inodestart, sb.bmapstart);
}
static struct inode* iget(uint dev, uint inum);
@ -178,12 +179,9 @@ ialloc(uint dev, short type)
int inum;
struct buf *bp;
struct dinode *dip;
struct superblock sb;
readsb(dev, &sb);
for(inum = 1; inum < sb.ninodes; inum++){
bp = bread(dev, IBLOCK(inum));
bp = bread(dev, IBLOCK(inum, sb));
dip = (struct dinode*)bp->data + inum%IPB;
if(dip->type == 0){ // a free inode
memset(dip, 0, sizeof(*dip));
@ -204,7 +202,7 @@ iupdate(struct inode *ip)
struct buf *bp;
struct dinode *dip;
bp = bread(ip->dev, IBLOCK(ip->inum));
bp = bread(ip->dev, IBLOCK(ip->inum, sb));
dip = (struct dinode*)bp->data + ip->inum%IPB;
dip->type = ip->type;
dip->major = ip->major;
@ -281,7 +279,7 @@ ilock(struct inode *ip)
release(&icache.lock);
if(!(ip->flags & I_VALID)){
bp = bread(ip->dev, IBLOCK(ip->inum));
bp = bread(ip->dev, IBLOCK(ip->inum, sb));
dip = (struct dinode*)bp->data + ip->inum%IPB;
ip->type = dip->type;
ip->major = dip->major;