[PATCH] fuse: check directory aliasing in mkdir

Check the created directory inode for aliases in the mkdir() method.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/fuse/dir.c

@@ -74,6 +74,19 @@ static int fuse_dentry_revalidate(struct dentry *entry, struct nameidata *nd)
 	return 1;
 }
 
+static int dir_alias(struct inode *inode)
+{
+	if (S_ISDIR(inode->i_mode)) {
+		/* Don't allow creating an alias to a directory  */
+		struct dentry *alias = d_find_alias(inode);
+		if (alias) {
+			dput(alias);
+			return 1;
+		}
+	}
+	return 0;
+}
+
 static struct dentry_operations fuse_dentry_operations = {
 	.d_revalidate	= fuse_dentry_revalidate,
 };
@@ -263,7 +276,7 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_req *req,
 	fuse_put_request(fc, req);
 
 	/* Don't allow userspace to do really stupid things... */
-	if ((inode->i_mode ^ mode) & S_IFMT) {
+	if (((inode->i_mode ^ mode) & S_IFMT) || dir_alias(inode)) {
 		iput(inode);
 		return -EIO;
 	}
@@ -874,14 +887,9 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
 	err = fuse_lookup_iget(dir, entry, &inode);
 	if (err)
 		return ERR_PTR(err);
-	if (inode && S_ISDIR(inode->i_mode)) {
-		/* Don't allow creating an alias to a directory  */
-		struct dentry *alias = d_find_alias(inode);
-		if (alias) {
-			dput(alias);
-			iput(inode);
-			return ERR_PTR(-EIO);
-		}
+	if (inode && dir_alias(inode)) {
+		iput(inode);
+		return ERR_PTR(-EIO);
 	}
 	d_add(entry, inode);
 	return NULL;