From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [PATCH] fs/locks.c fcntl_setlease did not check if a file was opened for writing before granting a read lease Date: Thu, 27 Nov 2003 16:50:43 +0000 Sender: linux-fsdevel-owner@vger.kernel.org Message-ID: <20031127165043.GA19669@mail.shareable.org> References: <000301c3b504$689afbf0$0201a8c0@joe> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "'Matthew Wilcox'" Return-path: Received: from mail.jlokier.co.uk ([81.29.64.88]:53121 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S264562AbTK0Qut (ORCPT ); Thu, 27 Nov 2003 11:50:49 -0500 To: "Joseph D. Wagner" Content-Disposition: inline In-Reply-To: <000301c3b504$689afbf0$0201a8c0@joe> List-Id: linux-fsdevel.vger.kernel.org Joseph D. Wagner wrote: > But I THINK this is how a patch would fix the problem, in theory. Sorry, it won't. > + if ((arg == F_RDLCK) > + && ((dentry->d_flags & O_WRONLY) > + || (dentry->d_flags & O_RDWR) > + || (dentry->d_flags & O_CREAT) > + || (dentry->d_flags & O_TRUNC) > + || (inode->i_flags & O_WRONLY) > + || (inode->i_flags & O_RDWR) > + || (inode->i_flags & O_CREAT) > + || (inode->i_flags & O_TRUNC))) > + goto out_unlock; dentry->d_flags is a combination of the S_ flags, not O_ flags. E.g. S_SYNC, S_NOATIME etc. inode->i_flags is a combination of the DCACHE_ flags. E.g. DCACHE_AUTOFS_PENDING, DCACHE_REFERENCED tc. To detect if anyone has the file open for writing, you'll a new count field which keeps track of writer references. Something like this: if ((arg == F_RDLCK) && ((atomic_read(&inode->i_writer_count) != 0))) You'll also need to modify all the places where that needs to be maintained. Btw, I'm not sure why the F_WRLCK case needs to check d_count and i_count. Isn't it enough to check d_count? Won't all opens reference the inode through a dentry?: > if ((arg == F_WRLCK) > && ((atomic_read(&dentry->d_count) > 1) > || (atomic_read(&inode->i_count) > 1))) -- Jamie