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

17e3cf15 · rtm · 8abe2bcf · 17e3cf15 · 17e3cf15 · 17e3cf15
--- a/Notes
+++ b/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
--- a/fd.c
+++ b/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];

--- a/fs.c
+++ b/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;
-  
-  cprintf("unlink(%s)\n", cp);
+  uint off, inum, dev;
  
-  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;
 }
--- a/init.c
+++ b/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);

--- a/ioapic.c
+++ b/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);
 }
--- a/picirq.c
+++ b/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. */

--- a/syscall.c
+++ b/syscall.c
@@ -284,6 +284,7 @@ sys_mknod(void)
    return -1;

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