[PATCH] Fix the handling of dentry on msdos_lookup() (1/4)

If d_splice_alias() doesn't find the alias dentry, it returns NULL.
Then, msdos_lookup() dereference the NULL, and Oopses. Fixed here.

The vfat_lookup() part is cleanup only.

fs/msdos/namei.c

@@ -222,22 +222,17 @@ struct dentry *msdos_lookup(struct inode *dir,struct dentry *dentry)
 	if (res)
 		goto out;
 add:
-	if (inode) {
-		dentry = d_splice_alias(inode, dentry);
-		dentry->d_op = &msdos_dentry_operations;
-	} else {
-		d_add(dentry, inode);
-		dentry = NULL;
-	}
 	res = 0;
+	dentry = d_splice_alias(inode, dentry);
+	if (dentry)
+		dentry->d_op = &msdos_dentry_operations;
 out:
 	if (bh)
 		fat_brelse(sb, bh);
 	unlock_kernel();
-	if (res)
-		return ERR_PTR(res);
-	else
+	if (!res)
 		return dentry;
+	return ERR_PTR(res);
 }
 
 /***** Creates a directory entry (name is already formatted). */

fs/vfat/namei.c

@@ -1021,16 +1021,12 @@ struct dentry *vfat_lookup(struct inode *dir,struct dentry *dentry)
 	unlock_kernel();
 	dentry->d_op = &vfat_dentry_ops[table];
 	dentry->d_time = dentry->d_parent->d_inode->i_version;
-	if (inode) {
-		dentry = d_splice_alias(inode, dentry);
-		if (dentry) {
-			dentry->d_op = &vfat_dentry_ops[table];
-			dentry->d_time = dentry->d_parent->d_inode->i_version;
-		}
-		return dentry;
+	dentry = d_splice_alias(inode, dentry);
+	if (dentry) {
+		dentry->d_op = &vfat_dentry_ops[table];
+		dentry->d_time = dentry->d_parent->d_inode->i_version;
 	}
-	d_add(dentry,inode);
-	return NULL;
+	return dentry;
 }
 
 int vfat_create(struct inode *dir,struct dentry* dentry,int mode)