diff --git a/fs.c b/fs.c
index 13fc935454b70d8826fa381fa6b3453173a2f38a..fe65338be8f39e01d252f5aac79e40cf88a10de6 100644
--- a/fs.c
+++ b/fs.c
@@ -141,6 +141,53 @@ iinit(void)
initlock(&icache.lock, "icache");
}
+static struct inode* iget(uint dev, uint inum);
+
+//PAGEBREAK!
+// Allocate a new inode with the given type on device dev.
+struct inode*
+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++){ // loop over inode blocks
+ bp = bread(dev, IBLOCK(inum));
+ dip = (struct dinode*)bp->data + inum%IPB;
+ if(dip->type == 0){ // a free inode
+ memset(dip, 0, sizeof(*dip));
+ dip->type = type;
+ bwrite(bp); // mark it allocated on the disk
+ brelse(bp);
+ return iget(dev, inum);
+ }
+ brelse(bp);
+ }
+ panic("ialloc: no inodes");
+}
+
+// Copy inode, which has changed, from memory to disk.
+void
+iupdate(struct inode *ip)
+{
+ struct buf *bp;
+ struct dinode *dip;
+
+ 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;
+ memmove(dip->addrs, ip->addrs, sizeof(ip->addrs));
+ bwrite(bp);
+ brelse(bp);
+}
+
// Find the inode with number inum on device dev
// and return the in-memory copy.
static struct inode*
@@ -262,51 +309,6 @@ iunlockput(struct inode *ip)
iput(ip);
}
-//PAGEBREAK!
-// Allocate a new inode with the given type on device dev.
-struct inode*
-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++){ // loop over inode blocks
- bp = bread(dev, IBLOCK(inum));
- dip = (struct dinode*)bp->data + inum%IPB;
- if(dip->type == 0){ // a free inode
- memset(dip, 0, sizeof(*dip));
- dip->type = type;
- bwrite(bp); // mark it allocated on the disk
- brelse(bp);
- return iget(dev, inum);
- }
- brelse(bp);
- }
- panic("ialloc: no inodes");
-}
-
-// Copy inode, which has changed, from memory to disk.
-void
-iupdate(struct inode *ip)
-{
- struct buf *bp;
- struct dinode *dip;
-
- 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;
- memmove(dip->addrs, ip->addrs, sizeof(ip->addrs));
- bwrite(bp);
- brelse(bp);
-}
-
//PAGEBREAK!
// Inode contents
//
@@ -336,7 +338,6 @@ bmap(struct inode *ip, uint bn)
ip->addrs[NDIRECT] = addr = balloc(ip->dev);
bp = bread(ip->dev, addr);
a = (uint*)bp->data;
-
if((addr = a[bn]) == 0){
a[bn] = addr = balloc(ip->dev);
bwrite(bp);
@@ -571,7 +572,7 @@ skipelem(char *path, char *name)
// If parent != 0, return the inode for the parent and copy the final
// path element into name, which must have room for DIRSIZ bytes.
static struct inode*
-namex(char *path, int parent, char *name)
+namex(char *path, int nameiparent, char *name)
{
struct inode *ip, *next;
@@ -586,7 +587,7 @@ namex(char *path, int parent, char *name)
iunlockput(ip);
return 0;
}
- if(parent && *path == '\0'){
+ if(nameiparent && *path == '\0'){
// Stop one level early.
iunlock(ip);
return ip;
@@ -598,7 +599,7 @@ namex(char *path, int parent, char *name)
iunlockput(ip);
ip = next;
}
- if(parent){
+ if(nameiparent){
iput(ip);
return 0;
}
diff --git a/initcode.S b/initcode.S
index 984d29fdc25d53faa40f0ad5a2f54d3d090f4c43..41e84f419f7d96120a93c83b282aaf0dae3acee1 100644
--- a/initcode.S
+++ b/initcode.S
@@ -8,7 +8,7 @@
start:
pushl $argv
pushl $init
- pushl $0
+ pushl $0 // where caller pc would be
movl $SYS_exec, %eax
int $T_SYSCALL
diff --git a/kalloc.c b/kalloc.c
index 6c6ca7ee5ac1857f9bcf70411653fc7b47f8b836..2730d57f878c693a1d8088c3305fbca515edaf4c 100644
--- a/kalloc.c
+++ b/kalloc.c
@@ -22,21 +22,20 @@ struct {
// Initialize free list of physical pages.
// This code cheats by just considering one megabyte of
-// pages after _end. Real systems would determine the
+// pages after end. Real systems would determine the
// amount of memory available in the system and use it all.
void
kinit(void)
{
- extern int end;
- uint mem;
- char *start;
+ extern char end[];
+ uint len;
+ char *p;
initlock(&kmem.lock, "kmem");
- start = (char*) &end;
- start = (char*) (((uint)start + PAGE) & ~(PAGE-1));
- mem = 256; // assume computer has 256 pages of RAM
- cprintf("mem = %d\n", mem * PAGE);
- kfree(start, mem * PAGE);
+ p = (char*)(((uint)end + PAGE) & ~(PAGE-1));
+ len = 256*PAGE; // assume computer has 256 pages of RAM, 1 MB
+ cprintf("mem = %d\n", len);
+ kfree(p, len);
}
// Free the len bytes of memory pointed at by v,
@@ -61,13 +60,7 @@ kfree(char *v, int len)
rend = (struct run*)((char*)r + r->len);
if(r <= p && p < rend)
panic("freeing free page");
- if(pend == r){ // p next to r: replace r with p
- p->len = len + r->len;
- p->next = r->next;
- *rp = p;
- goto out;
- }
- if(rend == p){ // r next to p: replace p with r
+ if(rend == p){ // r before p: expand r to include p
r->len += len;
if(r->next && r->next == pend){ // r now next to r->next?
r->len += r->next->len;
@@ -75,6 +68,12 @@ kfree(char *v, int len)
}
goto out;
}
+ if(pend == r){ // p before r: expand p to include, replace r
+ p->len = len + r->len;
+ p->next = r->next;
+ *rp = p;
+ goto out;
+ }
}
// Insert p before r in list.
p->len = len;
@@ -99,14 +98,11 @@ kalloc(int n)
acquire(&kmem.lock);
for(rp=&kmem.freelist; (r=*rp) != 0; rp=&r->next){
- if(r->len == n){
- *rp = r->next;
- release(&kmem.lock);
- return (char*)r;
- }
- if(r->len > n){
+ if(r->len >= n){
r->len -= n;
p = (char*)r + r->len;
+ if(r->len == 0)
+ *rp = r->next;
release(&kmem.lock);
return p;
}
diff --git a/sysfile.c b/sysfile.c
index efc42b00c1e7b925ff81612d2d728db82043c704..4d891c19a7695afd5daae52f5698dff0da9fa1be 100644
--- a/sysfile.c
+++ b/sysfile.c
@@ -44,6 +44,20 @@ fdalloc(struct file *f)
return -1;
}
+int
+sys_dup(void)
+{
+ struct file *f;
+ int fd;
+
+ if(argfd(0, 0, &f) < 0)
+ return -1;
+ if((fd=fdalloc(f)) < 0)
+ return -1;
+ filedup(f);
+ return fd;
+}
+
int
sys_read(void)
{
@@ -68,20 +82,6 @@ sys_write(void)
return filewrite(f, p, n);
}
-int
-sys_dup(void)
-{
- struct file *f;
- int fd;
-
- if(argfd(0, 0, &f) < 0)
- return -1;
- if((fd=fdalloc(f)) < 0)
- return -1;
- filedup(f);
- return fd;
-}
-
int
sys_close(void)
{
@@ -225,17 +225,15 @@ create(char *path, short type, short major, short minor)
if((ip = dirlookup(dp, name, &off)) != 0){
iunlockput(dp);
ilock(ip);
- if(ip->type != type || type != T_FILE){
- iunlockput(ip);
- return 0;
- }
- return ip;
- }
-
- if((ip = ialloc(dp->dev, type)) == 0){
- iunlockput(dp);
+ if(type == T_FILE && ip->type == T_FILE)
+ return ip;
+ iunlockput(ip);
return 0;
}
+
+ if((ip = ialloc(dp->dev, type)) == 0)
+ panic("create: ialloc");
+
ilock(ip);
ip->major = major;
ip->minor = minor;
@@ -298,6 +296,18 @@ sys_open(void)
return fd;
}
+int
+sys_mkdir(void)
+{
+ char *path;
+ struct inode *ip;
+
+ if(argstr(0, &path) < 0 || (ip = create(path, T_DIR, 0, 0)) == 0)
+ return -1;
+ iunlockput(ip);
+ return 0;
+}
+
int
sys_mknod(void)
{
@@ -315,18 +325,6 @@ sys_mknod(void)
return 0;
}
-int
-sys_mkdir(void)
-{
- char *path;
- struct inode *ip;
-
- if(argstr(0, &path) < 0 || (ip = create(path, T_DIR, 0, 0)) == 0)
- return -1;
- iunlockput(ip);
- return 0;
-}
-
int
sys_chdir(void)
{