From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 506913FCF for ; Thu, 16 Sep 2021 04:18:12 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id E19A36113E; Thu, 16 Sep 2021 04:18:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631765892; bh=07MliWGJfGAK+LhqNrCmA5FdUeLaldL2r83Wm9CtfwE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YNy7NcFBStdeULkAFLP1P/e8exSZKD/ocG0UoVxepppronIhq3DuOcEgY9DbIUpUx Ts2B4qsGqOZQhEMvr6kuBvwouJoPBd+IRhbRnBDTX1AjM6riW5JXJ+NY33FHu0gIXM nmKYOky1JW4mWHdpPchdsUvl8QmapizQ2FC12gQuBYvW7acddNmqmmpQAWLOMZv/gB ze8EhCyoCvudfheaRV91fy4ERv3QgoJAqNvLrDvL3B6aqnroPjQmF1icxewkc/fb+I zjsTo0QCjyPN+ngTpfAjH3w0myrvPJU4gL0bmaOkJjn8ZtE4XJBS1PYvTozRzYlyuR TcyJEfRDi+ACw== Date: Wed, 15 Sep 2021 21:18:11 -0700 From: "Darrick J. Wong" To: Shiyang Ruan Cc: hch@lst.de, linux-xfs@vger.kernel.org, dan.j.williams@intel.com, david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, rgoldwyn@suse.de, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [PATCH v9 8/8] xfs: Add dax dedupe support Message-ID: <20210916041811.GB34874@magnolia> References: <20210915104501.4146910-1-ruansy.fnst@fujitsu.com> <20210915104501.4146910-9-ruansy.fnst@fujitsu.com> <20210916003008.GE34830@magnolia> <38eeee6f-aa11-4c13-b7c0-2e48927b85dc@fujitsu.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <38eeee6f-aa11-4c13-b7c0-2e48927b85dc@fujitsu.com> On Thu, Sep 16, 2021 at 12:01:18PM +0800, Shiyang Ruan wrote: > > > On 2021/9/16 8:30, Darrick J. Wong wrote: > > On Wed, Sep 15, 2021 at 06:45:01PM +0800, Shiyang Ruan wrote: > > > Introduce xfs_mmaplock_two_inodes_and_break_dax_layout() for dax files > > > who are going to be deduped. After that, call compare range function > > > only when files are both DAX or not. > > > > > > Signed-off-by: Shiyang Ruan > > > Reviewed-by: Darrick J. Wong > > > Reviewed-by: Christoph Hellwig > > > --- > > > fs/xfs/xfs_file.c | 2 +- > > > fs/xfs/xfs_inode.c | 80 +++++++++++++++++++++++++++++++++++++++++--- > > > fs/xfs/xfs_inode.h | 1 + > > > fs/xfs/xfs_reflink.c | 4 +-- > > > 4 files changed, 80 insertions(+), 7 deletions(-) > > > > > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > > > index 2ef1930374d2..c3061723613c 100644 > > > --- a/fs/xfs/xfs_file.c > > > +++ b/fs/xfs/xfs_file.c > > > @@ -846,7 +846,7 @@ xfs_wait_dax_page( > > > xfs_ilock(ip, XFS_MMAPLOCK_EXCL); > > > } > > > -static int > > > +int > > > xfs_break_dax_layouts( > > > struct inode *inode, > > > bool *retry) > > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > > > index a4f6f034fb81..bdc084cdbf46 100644 > > > --- a/fs/xfs/xfs_inode.c > > > +++ b/fs/xfs/xfs_inode.c > > > @@ -3790,6 +3790,61 @@ xfs_iolock_two_inodes_and_break_layout( > > > return 0; > > > } > > > +static int > > > +xfs_mmaplock_two_inodes_and_break_dax_layout( > > > + struct xfs_inode *ip1, > > > + struct xfs_inode *ip2) > > > +{ > > > + int error, attempts = 0; > > > + bool retry; > > > + struct page *page; > > > + struct xfs_log_item *lp; > > > + > > > + if (ip1->i_ino > ip2->i_ino) > > > + swap(ip1, ip2); > > > + > > > +again: > > > + retry = false; > > > + /* Lock the first inode */ > > > + xfs_ilock(ip1, XFS_MMAPLOCK_EXCL); > > > + error = xfs_break_dax_layouts(VFS_I(ip1), &retry); > > > + if (error || retry) { > > > + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); > > > + if (error == 0 && retry) > > > + goto again; > > > + return error; > > > + } > > > + > > > + if (ip1 == ip2) > > > + return 0; > > > + > > > + /* Nested lock the second inode */ > > > + lp = &ip1->i_itemp->ili_item; > > > + if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) { > > > + if (!xfs_ilock_nowait(ip2, > > > + xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1))) { > > > + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); > > > + if ((++attempts % 5) == 0) > > > + delay(1); /* Don't just spin the CPU */ > > > + goto again; > > > + } > > > > I suspect we don't need this part for grabbing the MMAPLOCK^W pagecache > > invalidatelock. The AIL only grabs the ILOCK, never the IOLOCK or the > > MMAPLOCK. > > Maybe I have misunderstood this part. > > What I want is to lock the two inode nestedly. This code is copied from > xfs_lock_two_inodes(), which checks this AIL during locking two inode with > each of the three kinds of locks. It's totally reasonable to copy-paste the function you want and change it as needed... > But I also found the recent merged function: filemap_invalidate_lock_two() > just locks two inode directly without checking AIL. So, I am not if the AIL > check is needed in this case. ...especially when even the maintainer is only 99% sure that the AIL checking chunk here can be removed. Anyone else have an opinion? --D > > > > > + } else > > > + xfs_ilock(ip2, xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1)); > > > + /* > > > + * We cannot use xfs_break_dax_layouts() directly here because it may > > > + * need to unlock & lock the XFS_MMAPLOCK_EXCL which is not suitable > > > + * for this nested lock case. > > > + */ > > > + page = dax_layout_busy_page(VFS_I(ip2)->i_mapping); > > > + if (page && page_ref_count(page) != 1) { > > > > Do you think the patch "ext4/xfs: add page refcount helper" would be a > > good cleanup to head this series? > > > > https://lore.kernel.org/linux-xfs/20210913161604.31981-1-alex.sierra@amd.com/T/#m59cf7cd5c0d521ad487fa3a15d31c3865db88bdf > > Got it. > > > -- > Thanks, > Ruan > > > > > The rest of the logic looks ok. > > > > --D > > > > > + xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL); > > > + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); > > > + goto again; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > /* > > > * Lock two inodes so that userspace cannot initiate I/O via file syscalls or > > > * mmap activity. > > > @@ -3804,8 +3859,19 @@ xfs_ilock2_io_mmap( > > > ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2)); > > > if (ret) > > > return ret; > > > - filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping, > > > - VFS_I(ip2)->i_mapping); > > > + > > > + if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2))) { > > > + ret = xfs_mmaplock_two_inodes_and_break_dax_layout(ip1, ip2); > > > + if (ret) { > > > + inode_unlock(VFS_I(ip2)); > > > + if (ip1 != ip2) > > > + inode_unlock(VFS_I(ip1)); > > > + return ret; > > > + } > > > + } else > > > + filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping, > > > + VFS_I(ip2)->i_mapping); > > > + > > > return 0; > > > } > > > @@ -3815,8 +3881,14 @@ xfs_iunlock2_io_mmap( > > > struct xfs_inode *ip1, > > > struct xfs_inode *ip2) > > > { > > > - filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping, > > > - VFS_I(ip2)->i_mapping); > > > + if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2))) { > > > + xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL); > > > + if (ip1 != ip2) > > > + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); > > > + } else > > > + filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping, > > > + VFS_I(ip2)->i_mapping); > > > + > > > inode_unlock(VFS_I(ip2)); > > > if (ip1 != ip2) > > > inode_unlock(VFS_I(ip1)); > > > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h > > > index b21b177832d1..f7e26fe31a26 100644 > > > --- a/fs/xfs/xfs_inode.h > > > +++ b/fs/xfs/xfs_inode.h > > > @@ -472,6 +472,7 @@ enum xfs_prealloc_flags { > > > int xfs_update_prealloc_flags(struct xfs_inode *ip, > > > enum xfs_prealloc_flags flags); > > > +int xfs_break_dax_layouts(struct inode *inode, bool *retry); > > > int xfs_break_layouts(struct inode *inode, uint *iolock, > > > enum layout_break_reason reason); > > > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c > > > index 9d876e268734..3b99c9dfcf0d 100644 > > > --- a/fs/xfs/xfs_reflink.c > > > +++ b/fs/xfs/xfs_reflink.c > > > @@ -1327,8 +1327,8 @@ xfs_reflink_remap_prep( > > > if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest)) > > > goto out_unlock; > > > - /* Don't share DAX file data for now. */ > > > - if (IS_DAX(inode_in) || IS_DAX(inode_out)) > > > + /* Don't share DAX file data with non-DAX file. */ > > > + if (IS_DAX(inode_in) != IS_DAX(inode_out)) > > > goto out_unlock; > > > if (!IS_DAX(inode_in)) > > > -- > > > 2.33.0 > > > > > > > > > > >