From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 4A4B66B0055 for ; Thu, 18 Jun 2009 07:49:49 -0400 (EDT) From: OGAWA Hirofumi Subject: Re: [PATCH 07/11] vfs: Unmap underlying metadata of new data buffers only when buffer is mapped References: <1245088797-29533-1-git-send-email-jack@suse.cz> <1245088797-29533-8-git-send-email-jack@suse.cz> Date: Thu, 18 Jun 2009 20:51:13 +0900 In-Reply-To: <1245088797-29533-8-git-send-email-jack@suse.cz> (Jan Kara's message of "Mon, 15 Jun 2009 19:59:54 +0200") Message-ID: <87hbydkbf2.fsf@devron.myhome.or.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org To: Jan Kara Cc: LKML , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, npiggin@suse.de List-ID: Jan Kara writes: > 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. I may be missing something. However, isn't the delalloc buffer == (buffer_mapped() | buffer_delay())? Well, anyway, if buffer is not buffer_mapped(), e.g. truncate() works properly? Thanks. > 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); Is this needed for writepage? > } > } > bh = bh->b_this_page; -- OGAWA Hirofumi -- 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