From 08b1e0e42c358e4fc5f78d73f9af3df08db19a51 Mon Sep 17 00:00:00 2001
From: Bahadir Balban <bbalban@b-labs.co.uk>
Date: Sat, 16 Feb 2008 12:36:50 +0000
Subject: [PATCH] Adds tracking of hardlinks when reading a directory.

---
 tasks/fs0/include/fs.h      |  2 +-
 tasks/fs0/src/memfs/vnode.c | 19 +++++++++++++++----
 tasks/fs0/src/syscalls.c    |  2 +-
 tasks/fs0/src/vfs.c         |  8 --------
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/tasks/fs0/include/fs.h b/tasks/fs0/include/fs.h
index fc0a884..1b0829b 100644
--- a/tasks/fs0/include/fs.h
+++ b/tasks/fs0/include/fs.h
@@ -102,7 +102,7 @@ struct dirbuf {
 struct vnode {
 	unsigned long vnum;		/* Filesystem-wide unique vnode id */
 	int refcnt;			/* Reference counter */
-	int hardlinks;			/* Number of hard links */
+	int links;			/* Number of hard links */
 	struct superblock *sb;		/* Reference to superblock */
 	struct vnode_ops ops;		/* Operations on this vnode */
 	struct file_ops fops;		/* File-related operations on this vnode */
diff --git a/tasks/fs0/src/memfs/vnode.c b/tasks/fs0/src/memfs/vnode.c
index 325ac86..c50d7eb 100644
--- a/tasks/fs0/src/memfs/vnode.c
+++ b/tasks/fs0/src/memfs/vnode.c
@@ -334,15 +334,26 @@ int memfs_vnode_readdir(struct vnode *v)
 		list_add(&newd->child, &parent->children);
 
 		/*
-		 * Read the vnode for dentry by its vnode number.
+		 * Lookup the vnode for dentry by its vnode number. We call
+		 * vnode_lookup_byvnum instead of directly reading it because
+		 * this dentry might just be a link to a vnode that's already
+		 * in the vnode cache. If it's not there, the lookup function
+		 * allocates and reads it for us as well.
 		 */
-		newv = newd->vnode = vfs_alloc_vnode();
-		newv->vnum = memfsd[i].inum;
-		BUG_ON(newv->sb->ops->read_vnode(newv->sb, newv) < 0);
+		newv = newd->vnode = vfs_lookup_byvnum(v->sb, memfsd[i].inum);
+		if (!newv) {
+			printf("Filesystem seems to be broken. Directory has"
+			       "inode number: %d, but no such inode found.\n",
+				memfsd[i].inum);
+			BUG();
+		}
 
 		/* Assing this dentry as a name of its vnode */
 		list_add(&newd->vref, &newd->vnode->dentries);
 
+		/* Increase link count */
+		newv->links++;
+
 		/* Copy fields into generic dentry */
 		memcpy(newd->name, memfsd[i].name, MEMFS_DNAME_MAX);
 
diff --git a/tasks/fs0/src/syscalls.c b/tasks/fs0/src/syscalls.c
index bbc5bbc..3f359e3 100644
--- a/tasks/fs0/src/syscalls.c
+++ b/tasks/fs0/src/syscalls.c
@@ -69,6 +69,7 @@ int sys_open(l4id_t sender, const char *pathname, int flags, unsigned int mode)
 	/* Tell mm0 about opened vnode information */
 	BUG_ON(send_pager_opendata(sender, fd, v->vnum) < 0);
 
+	kfree(copypath);
 	return 0;
 }
 
@@ -97,7 +98,6 @@ int sys_mkdir(l4id_t sender, const char *pathname, unsigned int mode)
 	if ((err = vparent->ops.mkdir(vparent, newdir_name)) < 0)
 		return err;
 	kfree(pathbuf);
-
 	return 0;
 }
 
diff --git a/tasks/fs0/src/vfs.c b/tasks/fs0/src/vfs.c
index 4846255..d52a5c2 100644
--- a/tasks/fs0/src/vfs.c
+++ b/tasks/fs0/src/vfs.c
@@ -35,14 +35,6 @@ struct vnode *vfs_lookup_byvnum(struct superblock *sb, unsigned long vnum)
 		if (v->vnum == vnum)
 			return v;
 
-	/*
-	 * In the future it will be possible that a vnum known by the fd table
-	 * is not in the cache, because the cache will be able to grow and shrink.
-	 * But currently it just grows, so its a bug that a known vnum is not in
-	 * the cache.
-	 */
-	BUG();
-
 	/* Check the actual filesystem for the vnode */
 	v = vfs_alloc_vnode();
 	v->vnum = vnum;