Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754779Ab3IEPw6 (ORCPT ); Thu, 5 Sep 2013 11:52:58 -0400 Received: from mail-la0-f51.google.com ([209.85.215.51]:38451 "EHLO mail-la0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754718Ab3IEPwx (ORCPT ); Thu, 5 Sep 2013 11:52:53 -0400 MIME-Version: 1.0 X-Originating-IP: [86.59.245.170] In-Reply-To: <20130905145613.GR13318@ZenIV.linux.org.uk> References: <1378374284-1484-1-git-send-email-miklos@szeredi.hu> <1378374284-1484-5-git-send-email-miklos@szeredi.hu> <20130905111852.GP13318@ZenIV.linux.org.uk> <20130905120230.GA21170@tucsk.piliscsaba.szeredi.hu> <20130905123911.GA25538@tucsk.piliscsaba.szeredi.hu> <20130905132325.GQ13318@ZenIV.linux.org.uk> <20130905142651.GB25538@tucsk.piliscsaba.szeredi.hu> <20130905145613.GR13318@ZenIV.linux.org.uk> Date: Thu, 5 Sep 2013 17:52:51 +0200 Message-ID: Subject: Re: [PATCH 04/11] vfs: check unlinked ancestors before mount From: Miklos Szeredi To: Al Viro Cc: Linux-Fsdevel , Kernel Mailing List , "mszeredi@suse.cz" , David Howells , Steven Whitehouse , Trond Myklebust , Greg Kroah-Hartman Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1389 Lines: 38 On Thu, Sep 5, 2013 at 4:56 PM, Al Viro wrote: > I'd probably just do this, and to hell with helper functions... > > int d_set_mounted(struct dentry *dentry) > { > struct dentry *p; > int ret = 0; > write_seqlock(&rename_lock); > for (p = dentry; !IS_ROOT(p); p = p->d_parent) { > /* Need exclusion wrt. check_submounts_and_drop() */ > spin_lock(&p->d_lock); > if (unlikely(d_unhashed(p))) { > spin_unlock(&p->d_lock); > ret = -ENOENT; > goto out; > } > spin_unlock(&p->d_lock); > } > spin_lock(&dentry->d_lock); > dentry->d_flags |= DCACHE_MOUNTED; > spin_unlock(&dentry->d_lock); > out: > write_sequnlock(&rename_lock); > return ret; > } One issue with that: the dentry should be checked and marked within the same d_locked region. Because e.g. d_invalidate() relies solely on d_lock for non-dir mounts and d_mountpoint() checking, no rename_lock protection there. Thanks, Miklos -- 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/