From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 46B976B0253 for ; Tue, 16 Aug 2016 18:52:40 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id h186so195539665pfg.2 for ; Tue, 16 Aug 2016 15:52:40 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTP id xp2si34196242pab.19.2016.08.16.15.52.39 for ; Tue, 16 Aug 2016 15:52:39 -0700 (PDT) Date: Tue, 16 Aug 2016 16:52:27 -0600 From: Ross Zwisler Subject: Re: [PATCH 1/7] ext2: tell DAX the size of allocation holes Message-ID: <20160816225227.GA632@linux.intel.com> References: <20160815190918.20672-1-ross.zwisler@linux.intel.com> <20160815190918.20672-2-ross.zwisler@linux.intel.com> <20160816091025.GA27284@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160816091025.GA27284@quack2.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: Ross Zwisler , linux-kernel@vger.kernel.org, Theodore Ts'o , Alexander Viro , Andreas Dilger , Andrew Morton , Dan Williams , Dave Chinner , Jan Kara , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org On Tue, Aug 16, 2016 at 11:10:25AM +0200, Jan Kara wrote: > On Mon 15-08-16 13:09:12, Ross Zwisler wrote: > > When DAX calls ext2_get_block() and the file offset points to a hole we > > currently don't set bh_result->b_size. When we re-enable PMD faults DAX > > will need bh_result->b_size to tell it the size of the hole so it can > > decide whether to fault in a 4 KiB zero page or a 2 MiB zero page. > > > > For ext2 we always want DAX to use 4 KiB zero pages, so we just tell DAX > > that all holes are 4 KiB in size. > > > > Signed-off-by: Ross Zwisler > > --- > > fs/ext2/inode.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c > > index d5c7d09..c6d9763 100644 > > --- a/fs/ext2/inode.c > > +++ b/fs/ext2/inode.c > > @@ -773,6 +773,12 @@ int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_ > > if (ret > 0) { > > bh_result->b_size = (ret << inode->i_blkbits); > > ret = 0; > > + } else if (ret == 0 && IS_DAX(inode)) { > > I'd just drop the IS_DAX() check and set > > bh_result->b_size = 1 << inode->i_blkbits; > > IMO it's better to have things consistent between DAX & !DAX whenever > possible. Agreed, this is better. Fixed for v2, thanks! -- 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