From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:46200 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753008AbcLGTqq (ORCPT ); Wed, 7 Dec 2016 14:46:46 -0500 Date: Wed, 7 Dec 2016 14:46:34 -0500 From: Brian Foster Subject: Re: [PATCH 2/3] xfs: go straight to real allocations for direct I/O COW writes Message-ID: <20161207194634.GE23106@bfoster.bfoster> References: <1480971924-4864-1-git-send-email-hch@lst.de> <1480971924-4864-3-git-send-email-hch@lst.de> <20161207190008.GC23106@bfoster.bfoster> <20161207193709.GA27479@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161207193709.GA27479@lst.de> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Christoph Hellwig Cc: linux-xfs@vger.kernel.org, darrick.wong@oracle.com On Wed, Dec 07, 2016 at 08:37:09PM +0100, Christoph Hellwig wrote: > On Wed, Dec 07, 2016 at 02:00:09PM -0500, Brian Foster wrote: > > > - if (ap->flags & XFS_BMAPI_COWFORK) > > > - align = xfs_get_cowextsz_hint(ap->ip); > > > - else if (xfs_alloc_is_userdata(ap->datatype)) > > > + if (xfs_alloc_is_userdata(ap->datatype)) > > > > Doesn't this defeat the purpose (i.e., fragmentation avoidance via wider > > allocations) of the cowextszhint for direct I/O? I think it would be > > better to be consistent with the approach for traditional I/O + extsz > > and incorporate the alignment into the reservation. Perhaps the hunk of > > code that already does just that in xfs_iomap_write_direct() could be > > converted to a small helper and reused..? > > We're already doing the alignment to the cowextsize hint in > __xfs_reflink_allocate_cow so that we can take the cowextsize into > account. > Only for end_fsb... xfs_bmap_btalloc() calls xfs_bmap_extsize_align() with the alignment, which rounds out the start and end offsets. This same end_fsb code has already been removed from xfs_reflink_reserve_cow() for similar reasons. It should probably be removed from xfs_reflink_allocate_cow() as well. Brian > > > + resblks = XFS_DIOSTRAT_SPACE_RES(mp, end_fsb - *offset_fsb); > > > + > > > + error = xfs_qm_dqattach(ip, 0); > > > > This is already in the (only) caller. > > Yes, it can be dropped, although a superflous xfs_qm_dqattach is > totally harmless anyway. > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html