fix iget() bug that allocated in-use inode[] entries

Notes

@@ -357,7 +357,6 @@ OH! recursive interrupts will use up any amount of cpu[].stack!
 
 disk scheduling
 mkdir
-more than one directory content block
 sh arguments
 sh redirection
 indirect blocks
@@ -366,17 +365,10 @@ two bugs in unlink: don't just return if nlink > 0,
 is there a create/create race for same file name?
   resulting in two entries w/ same name in directory?
 
-namei
-  return just inode
-  return offset in dir where found, w/ dir locked, for unlink
-  return dir locked, for mknod
-
-is the offset alone useful? how do I read/write it?
-
 test: one process unlinks a file while another links to it
 test: simultaneous create of same file
 test: one process opens a file while another deletes it
 
-oy, mkfs wants dir size to be last written entry, but i
-  want it to be nblocks*512
-  maybe fix kernel code to handle former
+wdir should use writei, to avoid special-case block allocation
+  also readi
+  is dir locked? probably

fd.c

@@ -8,6 +8,8 @@
 #include "fd.h"
 #include "spinlock.h"
 #include "dev.h"
+#include "fs.h"
+#include "fsvar.h"
 
 struct spinlock fd_table_lock;
 struct devsw devsw[NDEV];

fs.c

@@ -54,7 +54,6 @@ balloc(uint dev)
   if (b >= size)
     panic("balloc: out of blocks\n");
 
-  cprintf ("balloc: allocate block %d\n", b);
   bp->data[bi/8] |= 0x1 << (bi % 8);
   bwrite (bp, BBLOCK(b, ninodes));  // mark it allocated on disk
   brelse(bp);
@@ -70,7 +69,6 @@ bfree(int dev, uint b)
   int ninodes;
   uchar m;
 
-  cprintf ("bfree: free block %d\n", b);
   bp = bread(dev, 1);
   sb = (struct superblock *) bp->data;
   ninodes = sb->ninodes;
@@ -93,13 +91,14 @@ bfree(int dev, uint b)
 struct inode *
 iget(uint dev, uint inum)
 {
-  struct inode *ip, *nip = 0;
+  struct inode *ip, *nip;
   struct dinode *dip;
   struct buf *bp;
 
   acquire(&inode_table_lock);
 
  loop:
+  nip = 0;
   for(ip = &inode[0]; ip < &inode[NINODE]; ip++){
     if(ip->count > 0 && ip->dev == dev && ip->inum == inum){
       if(ip->busy){
@@ -180,11 +179,9 @@ ialloc(uint dev, short type)
     brelse(bp);
   }
  
-  if (inum >= ninodes) {
+  if (inum >= ninodes) 
     panic ("ialloc: no inodes left\n");
-  }
 
-  cprintf ("ialloc: %d\n", inum);
   dip->type = type;
   bwrite (bp, IBLOCK(inum));   // mark it allocated on the disk
   brelse(bp);
@@ -195,7 +192,6 @@ ialloc(uint dev, short type)
 static void
 ifree(struct inode *ip)
 {
-  cprintf("ifree: %d\n", ip->inum);
   ip->type = 0;
   iupdate(ip);
 }
@@ -220,7 +216,7 @@ ilock(struct inode *ip)
 void
 iunlock(struct inode *ip)
 {
-  if(ip->busy != 1)
+  if(ip->busy != 1 || ip->count < 1)
     panic("iunlock");
 
   acquire(&inode_table_lock);
@@ -271,7 +267,7 @@ iput(struct inode *ip)
   if(ip->count < 1 || ip->busy != 1)
     panic("iput");
 
-  if ((ip->count <= 1) && (ip->nlink <= 0)) 
+  if ((ip->count == 1) && (ip->nlink == 0)) 
     iunlink(ip);
 
   acquire(&inode_table_lock);
@@ -498,8 +494,6 @@ mknod(char *cp, short type, short major, short minor)
 {
   struct inode *ip, *dp;
 
-  cprintf("mknod: %s %d %d %d\n", cp, type, major, minor);
-
   if ((dp = namei(cp, NAMEI_CREATE, 0)) == 0)
     return 0;
 
@@ -525,24 +519,17 @@ unlink(char *cp)
 {
   struct inode *ip, *dp;
   struct dirent de;
-  uint off, inum, cc;
+  uint off, inum, dev;
   
-  cprintf("unlink(%s)\n", cp);
-
-  if ((dp = namei(cp, NAMEI_DELETE, &off)) == 0) {
-    cprintf("unlink(%s) it doesn't exist\n", cp);
+  if ((dp = namei(cp, NAMEI_DELETE, &off)) == 0)
     return -1;
-  }
 
-  if((cc = readi(dp, (char*)&de, off, sizeof(de))) != sizeof(de) ||
-     de.inum == 0){
-    cprintf("off %d dp->size %d cc %d de.inum %d",
-            off, dp->size, cc, de.inum);
+  dev = dp->dev;
+
+  if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de) || de.inum == 0)
     panic("unlink no entry");
-  }
+
   inum = de.inum;
-  cprintf("dinum %d off %d de %s/%d\n", 
-          dp->inum, off, de.name, de.inum);
 
   memset(&de, 0, sizeof(de));
   if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
@@ -551,9 +538,7 @@ unlink(char *cp)
   iupdate(dp);
   iput(dp);
 
-  ip = iget(dp->dev, inum);
-  if(ip == 0)
-    panic("unlink no inode");
+  ip = iget(dev, inum);
 
   ip->nlink--;
 
@@ -568,14 +553,9 @@ link(char *name1, char *name2)
 {
   struct inode *ip, *dp;
 
-  cprintf("link(%s, %s)\n", name1, name2);
-
-  if ((ip = namei(name1, NAMEI_LOOKUP, 0)) == 0){
-    cprintf("  failed %s does not exist\n", name1);
+  if ((ip = namei(name1, NAMEI_LOOKUP, 0)) == 0)
     return -1;
-  }
   if(ip->type == T_DIR){
-    cprintf("  failed %s is a dir\n", name1);
     iput(ip);
     return -1;
   }
@@ -583,12 +563,10 @@ link(char *name1, char *name2)
   iunlock(ip);
 
   if ((dp = namei(name2, NAMEI_CREATE, 0)) == 0) {
-    cprintf("  failed %s exists\n", name2);
     idecref(ip);
     return -1;
   }
   if(dp->dev != ip->dev){
-    cprintf("  cross-device link\n");
     idecref(ip);
     iput(dp);
     return -1;
@@ -602,7 +580,5 @@ link(char *name1, char *name2)
   iput(dp);
   iput(ip);
 
-  cprintf("  succeeded\n");
-
   return 0;
 }

init.c

@@ -17,10 +17,7 @@ main(void)
   open("console", 1);
   open("console", 1);
 
-  puts("init...\n");
-
   while(1){
-    puts("running sh...\n");
     pid = fork();
     if(pid == 0){
       exec("sh", sh_args);

ioapic.c

@@ -43,7 +43,6 @@ ioapic_init(void)
   id = ioapic_read(io, IOAPIC_ID) >> APIC_ID_SHIFT;	
   if (id != ioapic_id)
     panic ("ioapic_init: id isn't equal to ioapic_id\n");
-  cprintf ("ioapic VER: 0x%x id %d nintr %d\n", l, id, nintr);
   for (i = 0; i < nintr; i++) {
     // active-hi and edge-triggered for ISA interrupts
     // Assume that pin 0 on the first I/O APIC is an ExtINT pin.
@@ -78,5 +77,4 @@ ioapic_enable (int irq, int cpunum)
   h &= ~IOART_DEST;
   h |= (cpunum << APIC_ID_SHIFT); 
   ioapic_write(io, IOAPIC_REDTBL_HI(irq), h);
-  cprintf("cpu%d: intr %d: lo 0x%x hi 0x%x\n", cpu(), irq, l, h);
 }

picirq.c

@@ -22,13 +22,6 @@ irq_setmask_8259A(ushort mask)
 
   outb(IO_PIC1+1, (char)mask);
   outb(IO_PIC2+1, (char)(mask >> 8));
-
-  cprintf("%d: enabled interrupts:", cpu());
-
-  for (i = 0; i < 16; i++)
-    if (~mask & (1<<i))
-      cprintf(" %d", i);
-  cprintf("\n");
 }
 
 /* Initialize the 8259A interrupt controllers. */

syscall.c

@@ -284,7 +284,8 @@ sys_mknod(void)
     return -1;
 
   nip = mknod (cp->mem + arg0, (short) arg1, (short) arg2, (short) arg3);
-  iput(nip);
+  if(nip)
+    iput(nip);
   return (nip == 0) ? -1 : 0;
 }