sanchayanmaity/xv6-cs450
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free inode only when noone is holding a pointer to it. should fix open-unlink-

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read problem, but untested
This commit is contained in:
kaashoek 2006-08-12 22:03:01 +00:00
parent 14938f9392
commit 22bac2cb9d
1 changed files with 43 additions and 36 deletions
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79
fs.c
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@ -226,6 +226,38 @@ iunlock(struct inode *ip)
release(&inode_table_lock);
}
uint
bmap(struct inode *ip, uint bn)
{
unsigned x;
if(bn >= NDIRECT)
panic("bmap 1");
x = ip->addrs[bn];
if(x == 0)
panic("bmap 2");
return x;
}
void
iunlink(struct inode *ip)
{
int i;
// free inode, its blocks, and remove dir entry
for (i = 0; i < NDIRECT; i++) {
if (ip->addrs[i] != 0) {
bfree(ip->dev, ip->addrs[i]);
ip->addrs[i] = 0;
}
}
ip->size = 0;
ip->major = 0;
ip->minor = 0;
iupdate(ip);
ifree(ip); // is this the right order?
}
// caller is releasing a reference to this inode.
// you must have the inode lock.
void
@ -234,6 +266,9 @@ iput(struct inode *ip)
if(ip->count < 1 || ip->busy != 1)
panic("iput");
if ((ip->count <= 1) && (ip->nlink <= 0))
iunlink(ip);
acquire(&inode_table_lock);
ip->count -= 1;
@ -256,21 +291,6 @@ idecref(struct inode *ip)
release(&inode_table_lock);
}
uint
bmap(struct inode *ip, uint bn)
{
unsigned x;
if(bn >= NDIRECT)
panic("bmap 1");
x = ip->addrs[bn];
if(x == 0)
panic("bmap 2");
return x;
}
#define min(a, b) ((a) < (b) ? (a) : (b))
void
stati(struct inode *ip, struct stat *st)
{
@ -281,6 +301,8 @@ stati(struct inode *ip, struct stat *st)
st->st_size = ip->size;
}
#define min(a, b) ((a) < (b) ? (a) : (b))
int
readi(struct inode *ip, char *dst, uint off, uint n)
{
@ -307,8 +329,6 @@ readi(struct inode *ip, char *dst, uint off, uint n)
return target - n;
}
#define MIN(a, b) ((a < b) ? a : b)
int
writei(struct inode *ip, char *addr, uint off, uint n)
{
@ -330,7 +350,7 @@ writei(struct inode *ip, char *addr, uint off, uint n)
if (b <= 0) return r;
ip->addrs[lbn] = b;
}
m = MIN(BSIZE - off % BSIZE, n-r);
m = min(BSIZE - off % BSIZE, n-r);
bp = bread(ip->dev, bmap(ip, off / BSIZE));
memmove (bp->data + off % BSIZE, addr, m);
bwrite (ip->dev, bp, bmap(ip, off/BSIZE));
@ -476,12 +496,13 @@ mknod(char *cp, short type, short major, short minor)
int
unlink(char *cp)
{
int i;
struct inode *ip, *dp;
struct inode *ip;
struct inode *dp;
struct dirent *ep = 0;
int off;
struct buf *bp = 0;
uint pinum;
if ((ip = namei(cp, &pinum)) == 0) {
cprintf("file to be unlinked doesn't exist\n");
@ -490,24 +511,10 @@ unlink(char *cp)
ip->nlink--;
if (ip->nlink > 0) {
iupdate(ip);
iput(ip); // is this the right order?
iput(ip);
return 0;
}
// free inode, its blocks, and remove dir entry
for (i = 0; i < NDIRECT; i++) {
if (ip->addrs[i] != 0) {
bfree(ip->dev, ip->addrs[i]);
ip->addrs[i] = 0;
}
}
ip->size = 0;
ip->major = 0;
ip->minor = 0;
iupdate(ip);
ifree(ip); // is this the right order?
dp = iget(rootdev, pinum);
for(off = 0; off < dp->size; off += BSIZE) {
bp = bread(dp->dev, bmap(dp, off / BSIZE));
@ -526,8 +533,8 @@ unlink(char *cp)
ep->inum = 0;
bwrite (dp->dev, bp, bmap(dp, off/BSIZE)); // write directory block
brelse(bp);
iput(ip);
iupdate (dp);
iput(dp);
iput(ip);
return 0;
}