From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id F41906B0062 for ; Mon, 6 Jul 2009 13:32:09 -0400 (EDT) Date: Mon, 6 Jul 2009 20:10:26 +0200 From: Nick Piggin Subject: Re: [rfc][patch 1/3] fs: new truncate sequence Message-ID: <20090706181026.GW2714@wotan.suse.de> References: <20090706165438.GQ2714@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, hch@infradead.org, jack@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Mon, Jul 06, 2009 at 08:00:07PM +0200, Miklos Szeredi wrote: > > Index: linux-2.6/mm/truncate.c > > =================================================================== > > --- linux-2.6.orig/mm/truncate.c > > +++ linux-2.6/mm/truncate.c > > @@ -465,3 +465,79 @@ int invalidate_inode_pages2(struct addre > > return invalidate_inode_pages2_range(mapping, 0, -1); > > } > > EXPORT_SYMBOL_GPL(invalidate_inode_pages2); > > + > > +/** > > + * truncate_pagecache - unmap mappings "freed" by truncate() syscall > > + * @inode: inode > > + * @old: old file offset > > + * @new: new file offset > > + * > > + * inode's new i_size must already be written before truncate_pagecache > > + * is called. > > + */ > > +void truncate_pagecache(struct inode * inode, loff_t old, loff_t new) > > +{ > > + VM_BUG_ON(inode->i_size != new); > > This is not true for fuse (and NFS?) as i_size isn't protected by > i_mutex during attribute revalidation, and so it can change during the > truncate. Hmm, that's probably OK now. filemap_fault has some tricky code to avoid faulting in pages past i_size, but since that has been changed to use page lock a while back, the i_size checks can probably go away. So long as your filesystems obviously have to ensure the truncate will not truncate the wrong pages, I can remove the VM_BUG_ON just fine. Thanks, Nick -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org