From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from e28smtp02.in.ibm.com ([122.248.162.2]:50630 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759424Ab2IFDFh (ORCPT ); Wed, 5 Sep 2012 23:05:37 -0400 Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 6 Sep 2012 08:35:34 +0530 Date: Thu, 6 Sep 2012 11:05:26 +0800 From: Guo Chao To: "J. Bruce Fields" Cc: Al Viro , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH 05/13] vfs: take i_mutex on renamed file Message-ID: <20120906030526.GB6679@yanx> References: <1346878524-10585-1-git-send-email-bfields@redhat.com> <1346878524-10585-6-git-send-email-bfields@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1346878524-10585-6-git-send-email-bfields@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Sep 05, 2012 at 04:55:15PM -0400, J. Bruce Fields wrote: > From: "J. Bruce Fields" > diff --git a/fs/namei.c b/fs/namei.c > index 1b46439..6156135 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -3658,6 +3658,7 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, > struct inode *new_dir, struct dentry *new_dentry) > { > struct inode *target = new_dentry->d_inode; > + struct inode *source = old_dentry->d_inode; > int error; > > error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); > @@ -3665,8 +3666,7 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, > return error; > > dget(new_dentry); > - if (target) > - mutex_lock(&target->i_mutex); > + lock_two_nondirectories(source, target); > > error = -EBUSY; > if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) > @@ -3681,8 +3681,7 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, > if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) > d_move(old_dentry, new_dentry); > out: > - if (target) > - mutex_unlock(&target->i_mutex); > + unlock_two_nondirectories(source, target); > dput(new_dentry); > return error; > } > This change also fixes a race between rename and mount. Apparently we avoid to rename source or target if they are mountpoint. But nothing prevents source being the mountpoint after d_mountpoint check because we do not hold its i_mutex. Thus we are actually able to rename a mountpoint. Rename directory should also need this care.