Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760933AbZFQKfv (ORCPT ); Wed, 17 Jun 2009 06:35:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754881AbZFQKfm (ORCPT ); Wed, 17 Jun 2009 06:35:42 -0400 Received: from cantor2.suse.de ([195.135.220.15]:51628 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752552AbZFQKfl (ORCPT ); Wed, 17 Jun 2009 06:35:41 -0400 Date: Wed, 17 Jun 2009 12:35:43 +0200 From: Nick Piggin To: Jan Kara Cc: LKML , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 07/11] vfs: Unmap underlying metadata of new data buffers only when buffer is mapped Message-ID: <20090617103543.GB29931@wotan.suse.de> References: <1245088797-29533-1-git-send-email-jack@suse.cz> <1245088797-29533-8-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1245088797-29533-8-git-send-email-jack@suse.cz> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2302 Lines: 61 On Mon, Jun 15, 2009 at 07:59:54PM +0200, Jan Kara wrote: > When we do delayed allocation of some buffer, we want to signal to VFS that > the buffer is new (set buffer_new) so that it properly zeros out everything. > But we don't have the buffer mapped yet so we cannot really unmap underlying > metadata in this state. Make VFS avoid doing unmapping of metadata when the > buffer is not yet mapped. Is this a seperate bugfix for delalloc filesystems? What is the error case of attempting to unmap underlying metadata of non mapped buffer? Won't translate to a serious bug will it? > > Signed-off-by: Jan Kara > --- > fs/buffer.c | 12 +++++++----- > 1 files changed, 7 insertions(+), 5 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 80e2630..7eb1710 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -1683,8 +1683,9 @@ static int __block_write_full_page(struct inode *inode, struct page *page, > if (buffer_new(bh)) { > /* blockdev mappings never come here */ > clear_buffer_new(bh); > - unmap_underlying_metadata(bh->b_bdev, > - bh->b_blocknr); > + if (buffer_mapped(bh)) > + unmap_underlying_metadata(bh->b_bdev, > + bh->b_blocknr); > } > } > bh = bh->b_this_page; > @@ -1869,8 +1870,9 @@ static int __block_prepare_write(struct inode *inode, struct page *page, > if (err) > break; > if (buffer_new(bh)) { > - unmap_underlying_metadata(bh->b_bdev, > - bh->b_blocknr); > + if (buffer_mapped(bh)) > + unmap_underlying_metadata(bh->b_bdev, > + bh->b_blocknr); > if (PageUptodate(page)) { > clear_buffer_new(bh); > set_buffer_uptodate(bh); > @@ -2683,7 +2685,7 @@ int nobh_write_begin(struct file *file, struct address_space *mapping, > goto failed; > if (!buffer_mapped(bh)) > is_mapped_to_disk = 0; > - if (buffer_new(bh)) > + if (buffer_new(bh) && buffer_mapped(bh)) > unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); > if (PageUptodate(page)) { > set_buffer_uptodate(bh); > -- > 1.6.0.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/