From: "J. Bruce Fields" <bfields@fieldses.org>
To: Guo Chao <yan@linux.vnet.ibm.com>
Cc: "J. Bruce Fields" <bfields@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 05/13] vfs: take i_mutex on renamed file
Date: Thu, 6 Sep 2012 13:51:18 -0400 [thread overview]
Message-ID: <20120906175118.GC21736@fieldses.org> (raw)
In-Reply-To: <20120906030526.GB6679@yanx>
On Thu, Sep 06, 2012 at 11:05:26AM +0800, Guo Chao wrote:
> On Wed, Sep 05, 2012 at 04:55:15PM -0400, J. Bruce Fields wrote:
> > From: "J. Bruce Fields" <bfields@redhat.com>
> > 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.
Do you have any practical way to reproduce that race?
--b.
next prev parent reply other threads:[~2012-09-06 17:51 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 20:55 [RFC PATCH 00/13] Implement NFSv4 delegations, take 4 J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 01/13] gfs2: Get rid of I_MUTEX_QUOTA usage J. Bruce Fields
2012-09-05 20:59 ` J. Bruce Fields
2012-09-06 14:27 ` Steven Whitehouse
2012-09-06 17:08 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 02/13] vfs: pull ext4's double-i_mutex-locking into common code J. Bruce Fields
2012-09-06 2:53 ` Guo Chao
2012-09-06 13:49 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 03/13] vfs: don't use PARENT/CHILD lock classes for non-directories J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 04/13] vfs: rename I_MUTEX_QUOTA now that it's not used for quotas J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 05/13] vfs: take i_mutex on renamed file J. Bruce Fields
2012-09-06 3:05 ` Guo Chao
2012-09-06 17:51 ` J. Bruce Fields [this message]
2012-09-07 2:27 ` Guo Chao
2012-09-07 21:39 ` J. Bruce Fields
2012-09-10 2:40 ` Guo Chao
2012-09-10 5:10 ` Ram Pai
2012-09-10 6:37 ` Guo Chao
2012-09-10 7:27 ` Ram Pai
2013-02-14 2:01 ` Al Viro
2012-09-10 14:35 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 06/13] locks: introduce new FL_DELEG lock flag J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 07/13] locks: implement delegations J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 08/13] namei: minor vfs_unlink cleanup J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 09/13] locks: break delegations on unlink J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 10/13] locks: helper functions for delegation breaking J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 11/13] locks: break delegations on rename J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 12/13] locks: break delegations on link J. Bruce Fields
2012-09-05 21:02 ` J. Bruce Fields
2012-09-06 11:01 ` Jeff Layton
2012-09-06 13:33 ` J. Bruce Fields
2012-09-05 20:55 ` [RFC PATCH 13/13] locks: break delegations on any attribute modification J. Bruce Fields
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