PDF at http://am.lcs.mit.edu/~rsc/xv6.pdf

Various changes made while offline.

 + bwrite sector argument is redundant; use b->sector.
 + reformatting of files for nicer PDF page breaks
 + distinguish between locked, unlocked inodes in type signatures
 + change FD_FILE to FD_INODE
 + move userinit (nee proc0init) to proc.c
 + move ROOTDEV to param.h
 + always parenthesize sizeof argument

BUGS

@@ -4,47 +4,11 @@ proc.c:
 	and be able to break out with an error return.
 	it is better if you check *before* sleep.
 
-	can swap procdump up after proc_kill
-	and then have proc_exit and proc_wait on same sheet
-
-	sched ->  switch2scheduler?  or just switch?
-
-	factor out switching and scheduling code from process code
-
-	shuffle for formatting
-
 syscall.c:
-	cannot convince runoff1 to split the extern lists to fill previous page completely.
-
-fs.c: split all name operations off in name.c?  (starting with namei but
-      wdir keep in fs.c)
-	locking?
-	shuffle for formatting
-
-pipe.c:
-	more comments?
-	comment how functions get called?
-
-sysfile.c:
-	is the sys_exec picture upside down?
-	can sys_open and sys_exec be simplified any?
-
-general:
-	sizeof parens?
-
-bio.c:
-	decide odd or even
-	bwrite doesn't need a second argument
-
-file.c:
-	move fileincref onto page 1?
-
-L=$HOME/mit/l
-(for i in *.c; do xoc -x xgnu -x ./nodecleq.zeta --typesonly $i; done) 2>&1 | grep warning
-
-saw random sharedfd failure.
-
-why does fdalloc consume reference?
+	cannot convince runoff1 to split the extern lists 
+	  to fill previous page completely.
 
-why mkdir and create?
+formatting:
+	file.c filewrite leaks onto next page
+	need to fix PAGEBREAK mechanism
 

bio.c

@@ -117,12 +117,11 @@ bread(uint dev, uint sector)
 // Write buf's contents to disk.
 // Must be locked.
 void
-bwrite(struct buf *b, uint sector)
+bwrite(struct buf *b)
 {
   if((b->flags & B_BUSY) == 0)
     panic("bwrite");
-
-  ide_rw(b->dev & 0xff, sector, b->data, 1, 0);
+  ide_rw(b->dev & 0xff, b->sector, b->data, 1, 0);
   b->flags |= B_VALID;
 }
 

bootmain.c

@@ -25,14 +25,14 @@
 //  * cmain() in this file takes over, 
 //    reads in the kernel and jumps to it.
 
+//PAGEBREAK!
 #include "types.h"
 #include "elf.h"
 #include "x86.h"
 
 #define SECTSIZE  512
 #define ELFHDR    ((struct elfhdr*) 0x10000) // scratch space
 
-void readsect(void*, uint);
 void readseg(uint, uint, uint);
 
 void
@@ -64,32 +64,6 @@ cmain(void)
     ;
 }
 
-// Read 'count' bytes at 'offset' from kernel into virtual address 'va'.
-// Might copy more than asked
-void
-readseg(uint va, uint count, uint offset)
-{
-  uint end_va;
-
-  va &= 0xFFFFFF;
-  end_va = va + count;
-
-  // round down to sector boundary
-  va &= ~(SECTSIZE - 1);
-
-  // translate from bytes to sectors, and kernel starts at sector 1
-  offset = (offset / SECTSIZE) + 1;
-
-  // If this is too slow, we could read lots of sectors at a time.
-  // We'd write more to memory than asked, but it doesn't matter --
-  // we load in increasing order.
-  while(va < end_va) {
-    readsect((uchar*) va, offset);
-    va += SECTSIZE;
-    offset++;
-  }
-}
-
 void
 waitdisk(void)
 {
@@ -98,6 +72,7 @@ waitdisk(void)
     ;
 }
 
+// Read a single sector at offset into dst.
 void
 readsect(void *dst, uint offset)
 {
@@ -118,3 +93,29 @@ readsect(void *dst, uint offset)
   insl(0x1F0, dst, SECTSIZE/4);
 }
 
+// Read 'count' bytes at 'offset' from kernel into virtual address 'va'.
+// Might copy more than asked.
+void
+readseg(uint va, uint count, uint offset)
+{
+  uint end_va;
+
+  va &= 0xFFFFFF;
+  end_va = va + count;
+
+  // round down to sector boundary
+  va &= ~(SECTSIZE - 1);
+
+  // translate from bytes to sectors, and kernel starts at sector 1
+  offset = (offset / SECTSIZE) + 1;
+
+  // If this is too slow, we could read lots of sectors at a time.
+  // We'd write more to memory than asked, but it doesn't matter --
+  // we load in increasing order.
+  while(va < end_va) {
+    readsect((uchar*) va, offset);
+    va += SECTSIZE;
+    offset++;
+  }
+}
+

defs.h

@@ -24,6 +24,7 @@ int proc_kill(int);
 int proc_wait(void);
 void yield(void);
 void procdump(void);
+void userinit(void);
 
 // setjmp.S
 struct jmpbuf;
@@ -117,30 +118,31 @@ void ide_rw(int, uint, void*, uint, int);
 void binit(void);
 struct buf;
 struct buf* bread(uint, uint);
-void bwrite(struct buf*, uint);
+void bwrite(struct buf*);
 void brelse(struct buf*);
 
 // fs.c
 struct inode;
+struct uinode;
 void iinit(void);
-void ilock(struct inode*);
-void iunlock(struct inode*);
-void idecref(struct inode*);
-struct inode* iincref(struct inode*);
-void iput(struct inode*);
-struct inode* namei(char*);
+struct inode* ilock(struct uinode*);
+struct uinode* iunlock(struct inode*);
+void iput(struct uinode*);
+struct uinode* idup(struct uinode*);
+struct uinode* namei(char*);
 void stati(struct inode*, struct stat*);
 int readi(struct inode*, char*, uint, uint);
 int writei(struct inode*, char*, uint, uint);
-struct inode* mknod(char*, short, short, short);
-int unlink(char*);
-int link(char*, char*);
-struct inode* igetroot(void);
-int mkdir(char *path);
-struct inode* create(char *path);
+int dirlink(struct inode *dp, char *name, uint ino);
+struct uinode* dirlookup(struct inode *dp, char *name, uint *poff);
+void iupdate(struct inode *ip);
+int namecmp(const char *s, const char *t);
+struct uinode* ialloc(uint, short);
+struct uinode* nameiparent(char *path, char *name);
 
 // exec.c
 int exec(char*, char**);
 
 // number of elements in fixed-size array
 #define NELEM(x) (sizeof(x)/sizeof((x)[0]))
+

exec.c

@@ -19,7 +19,7 @@ int
 exec(char *path, char **argv)
 {
   uint sz, sp, p1, p2;
-  int i, nargs, argbytes, len;
+  int i, nargs, argbytes, len, off;
   struct inode *ip;
   struct elfhdr elf;
   struct proghdr ph;
@@ -29,7 +29,7 @@ exec(char *path, char **argv)
   sz = 0;
   mem = 0;
 
-  if((ip = namei(path)) == 0)
+  if((ip = ilock(namei(path))) == 0)
     return -1;
 
   if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
@@ -38,9 +38,8 @@ exec(char *path, char **argv)
   if(elf.magic != ELF_MAGIC)
     goto bad;
 
-  for(i = 0; i < elf.phnum; i++){
-    if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
-             sizeof(ph)) != sizeof(ph))
+  for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
+    if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
       goto bad;
     if(ph.type != ELF_PROG_LOAD)
       continue;
@@ -94,17 +93,16 @@ exec(char *path, char **argv)
   for(last=s=path; *s; s++)
     if(*s == '/')
       last = s+1;
-  safestrcpy(cp->name, last, sizeof cp->name);
+  safestrcpy(cp->name, last, sizeof(cp->name));
 
   // commit to the new image.
   kfree(cp->mem, cp->sz);
   cp->sz = sz;
   cp->mem = mem;
   mem = 0;
 
-  for(i = 0; i < elf.phnum; i++){
-    if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
-             sizeof(ph)) != sizeof(ph))
+  for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
+    if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
       goto bad2;
     if(ph.type != ELF_PROG_LOAD)
       continue;
@@ -115,7 +113,7 @@ exec(char *path, char **argv)
     memset(cp->mem + ph.va + ph.filesz, 0, ph.memsz - ph.filesz);
   }
 
-  iput(ip);
+  iput(iunlock(ip));
 
   cp->tf->eip = elf.entry;
   cp->tf->esp = sp;
@@ -126,11 +124,11 @@ exec(char *path, char **argv)
  bad:
   if(mem)
     kfree(mem, sz);
-  iput(ip);
+  iput(iunlock(ip));
   return -1;
 
  bad2:
-  iput(ip);
+  iput(iunlock(ip));
   proc_exit();
   return 0;
 }

file.c

@@ -11,9 +11,8 @@
 #include "fs.h"
 #include "fsvar.h"
 
-struct spinlock file_table_lock;
 struct devsw devsw[NDEV];
-
+struct spinlock file_table_lock;
 struct file file[NFILE];
 
 void
@@ -22,7 +21,7 @@ fileinit(void)
   initlock(&file_table_lock, "file_table");
 }
 
-// Allocate a file structure
+// Allocate a file structure.
 struct file*
 filealloc(void)
 {
@@ -57,16 +56,17 @@ int
 fileread(struct file *f, char *addr, int n)
 {
   int r;
+  struct inode *ip;
 
   if(f->readable == 0)
     return -1;
   if(f->type == FD_PIPE)
     return pipe_read(f->pipe, addr, n);
-  if(f->type == FD_FILE){
-    ilock(f->ip);
-    if((r = readi(f->ip, addr, f->off, n)) > 0)
+  if(f->type == FD_INODE){
+    ip = ilock(f->ip);
+    if((r = readi(ip, addr, f->off, n)) > 0)
       f->off += r;
-    iunlock(f->ip);
+    iunlock(ip);
     return r;
   }
   panic("fileread");
@@ -77,16 +77,17 @@ int
 filewrite(struct file *f, char *addr, int n)
 {
   int r;
+  struct inode *ip;
 
   if(f->writable == 0)
     return -1;
   if(f->type == FD_PIPE)
     return pipe_write(f->pipe, addr, n);
-  if(f->type == FD_FILE){
-    ilock(f->ip);
-    if((r = writei(f->ip, addr, f->off, n)) > 0)
+  if(f->type == FD_INODE){
+    ip = ilock(f->ip);
+    if((r = writei(ip, addr, f->off, n)) > 0)
       f->off += r;
-    iunlock(f->ip);
+    iunlock(ip);
     return r;
   }
   panic("filewrite");
@@ -96,10 +97,12 @@ filewrite(struct file *f, char *addr, int n)
 int
 filestat(struct file *f, struct stat *st)
 {
-  if(f->type == FD_FILE){
-    ilock(f->ip);
-    stati(f->ip, st);
-    iunlock(f->ip);
+  struct inode *ip;
+
+  if(f->type == FD_INODE){
+    ip = ilock(f->ip);
+    stati(ip, st);
+    iunlock(ip);
     return 0;
   }
   return -1;
@@ -110,6 +113,7 @@ void
 fileclose(struct file *f)
 {
   struct file ff;
+
   acquire(&file_table_lock);
 
   if(f->ref < 1 || f->type == FD_CLOSED)
@@ -127,8 +131,8 @@ fileclose(struct file *f)
 
   if(ff.type == FD_PIPE)
     pipe_close(ff.pipe, ff.writable);
-  else if(ff.type == FD_FILE)
-    idecref(ff.ip);
+  else if(ff.type == FD_INODE)
+    iput(ff.ip);
   else
     panic("fileclose");
 }

file.h

@@ -1,9 +1,9 @@
 struct file {
-  enum { FD_CLOSED, FD_NONE, FD_PIPE, FD_FILE } type;
+  enum { FD_CLOSED, FD_NONE, FD_PIPE, FD_INODE } type;
   int ref; // reference count
   char readable;
   char writable;
   struct pipe *pipe;
-  struct inode *ip;
+  struct uinode *ip;
   uint off;
 };