From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:49992 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726965AbfBYMzL (ORCPT ); Mon, 25 Feb 2019 07:55:11 -0500 Date: Mon, 25 Feb 2019 07:55:08 -0500 From: Brian Foster Subject: Re: [PATCH 2/2] xfs: rework breaking of shared extents in xfs_file_iomap_begin Message-ID: <20190225125508.GB2916@bfoster> References: <155104025871.24373.7462613353398620970.stgit@magnolia> <155104026500.24373.14839198455533713908.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155104026500.24373.14839198455533713908.stgit@magnolia> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org On Sun, Feb 24, 2019 at 12:31:05PM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong > > Rework the data flow in xfs_file_iomap_begin where we decide if we have > to break shared extents. > > Signed-off-by: Darrick J. Wong > --- Reviewed-by: Brian Foster > fs/xfs/xfs_iomap.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > index a376fb2d4b94..a3043b1bcd9a 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -982,7 +982,7 @@ xfs_file_iomap_begin( > * been done up front, so we don't need to do them here. > */ > if (xfs_is_cow_inode(ip)) { > - struct xfs_bmbt_irec orig = imap; > + struct xfs_bmbt_irec cmap; > bool convert_now = (flags & IOMAP_DIRECT); > > /* if zeroing doesn't need COW allocation, then we are done. */ > @@ -991,7 +991,8 @@ xfs_file_iomap_begin( > goto out_found; > > /* may drop and re-acquire the ilock */ > - error = xfs_reflink_allocate_cow(ip, &imap, &shared, &lockmode, > + cmap = imap; > + error = xfs_reflink_allocate_cow(ip, &cmap, &shared, &lockmode, > convert_now); > if (error) > goto out_unlock; > @@ -1001,10 +1002,12 @@ xfs_file_iomap_begin( > * previous block (if there was any) so that the higher level > * write code can perform read-modify-write operations. For > * direct I/O code, which must be block aligned we need to > - * report the newly allocated address. > + * report the newly allocated address. If the data fork has > + * a hole, copy the COW fork mapping to avoid allocating to > + * the data fork. > */ > - if (!convert_now && orig.br_startblock != HOLESTARTBLOCK) > - imap = orig; > + if (convert_now || imap.br_startblock == HOLESTARTBLOCK) > + imap = cmap; > > end_fsb = imap.br_startoff + imap.br_blockcount; > length = XFS_FSB_TO_B(mp, end_fsb) - offset; >