added iupdate to list of file system functions

defs.h

@@ -44,14 +44,17 @@ void            iput(struct inode*);
 void            ilock(struct inode*);
 void            iunlock(struct inode*);
 void            iunlockput(struct inode*);
-void            iupdate(struct inode*);
 int             namecmp(const char*, const char*);
 struct inode*   namei(char*);
 struct inode*   nameiparent(char*, char*);
 void            stati(struct inode*, struct stat*);
-// fs-specific functions that are accessed through inode->i_func
+
+// fs-specific functions that should only be accessed through inode->i_func
 int             fs_readi(struct inode*, char*, uint, uint);
 int             fs_writei(struct inode*, char*, uint, uint);
+void            fs_ipopulate(struct inode* ip);
+void            fs_iupdate(struct inode*);
+
 
 
 // ide.c

file.h

@@ -8,10 +8,22 @@ struct file {
   uint off;
 };
 
+/* file-system specific functions that are maintained for each
+   inode. When a new in-memory inode is allocated using iget(),
+   the parent inode is now passed in, and the functions are inherited.
+
+   If no parent is passed in, the standard file-system functions are assigned. 
+
+   WARNING: this list of functions is likely incomplete, meaning that some operation
+            may not be supported in new file systems introduced. To improve
+            generality, add new file system function pointers here as needed.
+*/
+
 struct inode_functions {  
-  void (*ipopulate)(struct inode*);  
-  int (*readi)(struct inode*, char*, uint, uint);
-  int (*writei)(struct inode*, char*, uint, uint);
+  void (*ipopulate)(struct inode*);                   // fill in inode details
+  void (*iupdate)(struct inode*);                     // write inode details back to disk
+  int (*readi)(struct inode*, char*, uint, uint);     // read from file contents
+  int (*writei)(struct inode*, char*, uint, uint);    // write to file contents
 }; 
 
 #define NDIRECT 12

fs.c

@@ -25,8 +25,7 @@ static void itrunc(struct inode*);
 
 // fs inode functions
 
-void fs_ipopulate(struct inode* ip);
-struct inode_functions fs_i_func = { fs_ipopulate, fs_readi, fs_writei };      
+struct inode_functions fs_i_func = { fs_ipopulate, fs_iupdate, fs_readi, fs_writei };      
 
 // Read the super block.
 void
@@ -204,7 +203,7 @@ ialloc(uint dev, short type, struct inode* parent)
 
 // Copy a modified in-memory inode to disk.
 void
-iupdate(struct inode *ip)
+fs_iupdate(struct inode *ip)
 {
   struct buf *bp;
   struct dinode *dip;
@@ -346,7 +345,7 @@ iput(struct inode *ip)
     release(&icache.lock);
     itrunc(ip);
     ip->type = 0;
-    iupdate(ip);
+    ip->i_func->iupdate(ip);
     acquire(&icache.lock);
     ip->flags = 0;
     wakeup(ip);
@@ -435,7 +434,7 @@ itrunc(struct inode *ip)
   }
 
   ip->size = 0;
-  iupdate(ip);
+  ip->i_func->iupdate(ip);
 }
 
 // Copy stat information from inode.
@@ -506,7 +505,7 @@ fs_writei(struct inode *ip, char *src, uint off, uint n)
 
   if(n > 0 && off > ip->size){
     ip->size = off;
-    iupdate(ip);
+    ip->i_func->iupdate(ip);
   }
   return n;
 }

sysfile.c

@@ -135,7 +135,7 @@ sys_link(void)
   }
 
   ip->nlink++;
-  iupdate(ip);
+  ip->i_func->iupdate(ip);
   iunlock(ip);
 
   if((dp = nameiparent(new, name)) == 0)
@@ -155,7 +155,7 @@ sys_link(void)
 bad:
   ilock(ip);
   ip->nlink--;
-  iupdate(ip);
+  ip->i_func->iupdate(ip);
   iunlockput(ip);
   end_op();
   return -1;
@@ -217,12 +217,12 @@ sys_unlink(void)
     panic("unlink: writei");
   if(ip->type == T_DIR){
     dp->nlink--;
-    iupdate(dp);
+    dp->i_func->iupdate(dp);
   }
   iunlockput(dp);
 
   ip->nlink--;
-  iupdate(ip);
+  ip->i_func->iupdate(ip);
   iunlockput(ip);
 
   end_op();
@@ -262,11 +262,11 @@ create(char *path, short type, short major, short minor)
   ip->major = major;
   ip->minor = minor;
   ip->nlink = 1;
-  iupdate(ip);
+  ip->i_func->iupdate(ip);
 
   if(type == T_DIR){  // Create . and .. entries.
     dp->nlink++;  // for ".."
-    iupdate(dp);
+    dp->i_func->iupdate(dp);
     // No ip->nlink++ for ".": avoid cyclic ref count.
     if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0)
       panic("create dots");