vfs: store directory entry pointer to vnode

In order to unmount, we need to drop all vnodes on a mount point, so we
need to find all directory entries pointing to them.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

fs/vfs/vfs_lookup.c

@@ -73,6 +73,7 @@ dentry_alloc(struct vnode *vp, const char *path)
 	dp->d_vnode = vp;
 	dp->d_mount = mp;
 	dp->d_path = strdup(path);
+	vn_add_name(vp, dp);
 
 	mutex_lock(&dentry_hash_lock);
 	LIST_INSERT_HEAD(&dentry_hash_table[dentry_hash(mp, path)], dp, d_link);
@@ -121,6 +122,8 @@ drele(struct dentry *dp)
 		return;
 	}
 	LIST_REMOVE(dp, d_link);
+	vn_del_name(dp->d_vnode, dp);
+
 	mutex_unlock(&dentry_hash_lock);
 
 	vrele(dp->d_vnode);
@@ -214,8 +217,8 @@ namei(char *path, struct dentry **dpp)
 				return error;
 			}
 
-			dp = dentry_alloc(vp, node);
 			vn_unlock(dvp);
+			dp = dentry_alloc(vp, node);
 			vput(vp);
 
 			if (!dp) {

fs/vfs/vfs_vnode.c

@@ -174,6 +174,7 @@ vget(struct mount *mp, const char *path)
 		free(vp);
 		return NULL;
 	}
+	LIST_INIT(&vp->v_names);
 	vp->v_mount = mp;
 	vp->v_refcnt = 1;
 	vp->v_op = mp->m_op->vfs_vnops;
@@ -470,3 +471,18 @@ vnode_init(void)
 	for (i = 0; i < VNODE_BUCKETS; i++)
 		LIST_INIT(&vnode_table[i]);
 }
+
+void vn_add_name(struct vnode *vp, struct dentry *dp)
+{
+	vn_lock(vp);
+	LIST_INSERT_HEAD(&vp->v_names, dp, d_names_link);
+	vn_unlock(vp);
+}
+
+void vn_del_name(struct vnode *vp, struct dentry *dp)
+{
+	vn_lock(vp);
+	LIST_REMOVE(dp, d_names_link);
+	vn_unlock(vp);
+}
+

include/osv/dentry.h

@@ -19,6 +19,7 @@ struct dentry {
 	char		*d_path;	/* pointer to path in fs */
 	struct vnode	*d_vnode;
 	struct mount	*d_mount;
+	LIST_ENTRY(dentry) d_names_link; /* link fo vnode::d_names */
 };
 
 #endif /* _OSV_DENTRY_H */

include/osv/vnode.h

@@ -74,6 +74,7 @@ struct vnode {
 	mode_t		v_mode;		/* file mode */
 	off_t		v_size;		/* file size */
 	mutex_t		v_lock;		/* lock for this vnode */
+	LIST_HEAD(, dentry) v_names;	/* directory entries pointing at this */
 	int		v_nrlocks;	/* lock count (for debug) */
 	char		*v_path;	/* pointer to path in fs */
 	void		*v_data;	/* private data for fs */
@@ -198,6 +199,8 @@ void	 vref(struct vnode *);
 void	 vrele(struct vnode *);
 int	 vcount(struct vnode *);
 void	 vflush(struct mount *);
+void vn_add_name(struct vnode *, struct dentry *);
+void vn_del_name(struct vnode *, struct dentry *);
 
 extern enum vtype iftovt_tab[];
 extern int vttoif_tab[];