From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guo Chao Subject: Re: [RFC PATCH 05/13] vfs: take i_mutex on renamed file Date: Thu, 6 Sep 2012 11:05:26 +0800 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 Cc: Al Viro , linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "J. Bruce Fields" Return-path: Content-Disposition: inline In-Reply-To: <1346878524-10585-6-git-send-email-bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org 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. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html