Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946217AbWJTElG (ORCPT ); Fri, 20 Oct 2006 00:41:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946228AbWJTElG (ORCPT ); Fri, 20 Oct 2006 00:41:06 -0400 Received: from smtp.osdl.org ([65.172.181.4]:54719 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1946217AbWJTElD (ORCPT ); Fri, 20 Oct 2006 00:41:03 -0400 Date: Thu, 19 Oct 2006 21:40:56 -0700 From: Andrew Morton To: Trond Myklebust Cc: Linus Torvalds , Al Viro , linux-kernel@vger.kernel.org, nfs@lists.sourceforge.net, Miklos Szeredi Subject: Re: [PATCH 1/2] VFS: Make d_materialise_unique() enforce directory uniqueness Message-Id: <20061019214056.6f82641b.akpm@osdl.org> In-Reply-To: <20061019210358.6797.64655.stgit@lade.trondhjem.org> References: <1161291638.5506.9.camel@lade.trondhjem.org> <20061019210358.6797.64655.stgit@lade.trondhjem.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1347 Lines: 45 On Thu, 19 Oct 2006 17:03:58 -0400 Trond Myklebust wrote: > +static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) > +{ > + struct mutex *m1 = NULL, *m2 = NULL; > + struct dentry *ret; > + > + /* If alias and dentry share a parent, then no extra locks required */ > + if (alias->d_parent == dentry->d_parent) > + goto out_unalias; > + > + /* Check for loops */ > + ret = ERR_PTR(-ELOOP); > + if (d_isparent(alias, dentry)) > + goto out_err; > + > + /* See lock_rename() */ > + ret = ERR_PTR(-EBUSY); > + if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) > + goto out_err; > + m1 = &dentry->d_sb->s_vfs_rename_mutex; > + if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) > + goto out_err; > + m2 = &alias->d_parent->d_inode->i_mutex; > +out_unalias: > + d_move_locked(alias, dentry); > + ret = alias; > +out_err: > + spin_unlock(&dcache_lock); > + if (m2) > + mutex_unlock(m2); > + if (m1) > + mutex_unlock(m1); > + return ret; > +} The locking in there is, of course, gruesome. There is no way in which it can be made reliable? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/