From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:48982 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726685AbfDBSgp (ORCPT ); Tue, 2 Apr 2019 14:36:45 -0400 Date: Tue, 2 Apr 2019 10:56:32 -0700 From: "Darrick J. Wong" Subject: Re: [PATCH] xfs: return correct XFS_IOC_DIOINFO for DAX inode Message-ID: <20190402175632.GD5147@magnolia> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Eric Sandeen Cc: linux-xfs , Jeff Moyer On Tue, Apr 02, 2019 at 10:44:38AM -0500, Eric Sandeen wrote: > pmem is byte addressable, and indeed byte-aligned DIO works on > a DAX file. So, teach XFS_IOC_DIOINFO to return the correct > alignment information if IS_DAX(inode). If it's a DAX filesystem, do we want to try to steer people towards things like 2MB pages since (in theory) we can get away with fewer page table mappings? And (seeing as that's mmap that cares, not directio) would advertising preferential page mapping sizes be more appropriate advertised in a different ioctl? --D > Signed-off-by: Eric Sandeen > --- > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 6ecdbb3..35eae7d 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -1919,12 +1919,21 @@ xfs_file_ioctl( > } > case XFS_IOC_DIOINFO: { > struct dioattr da; > - xfs_buftarg_t *target = > - XFS_IS_REALTIME_INODE(ip) ? > - mp->m_rtdev_targp : mp->m_ddev_targp; > > - da.d_mem = da.d_miniosz = target->bt_logical_sectorsize; > - da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1); > + if (IS_DAX(inode)) { > + /* pmem is byte addressable */ > + da.d_mem = 1; > + da.d_miniosz = 1; > + da.d_maxiosz = INT_MAX; > + } else { > + xfs_buftarg_t *target = > + XFS_IS_REALTIME_INODE(ip) ? > + mp->m_rtdev_targp : mp->m_ddev_targp; > + > + da.d_mem = target->bt_logical_sectorsize; > + da.d_miniosz = target->bt_logical_sectorsize; > + da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1); > + } > > if (copy_to_user(arg, &da, sizeof(da))) > return -EFAULT; >