From: Brian Foster <bfoster@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/5] xfs: cancel COW blocks before swapext
Date: Thu, 27 Sep 2018 11:07:31 -0400 [thread overview]
Message-ID: <20180927150730.GA3743@bfoster> (raw)
In-Reply-To: <20180920144220.2181-2-hch@lst.de>
On Thu, Sep 20, 2018 at 04:42:16PM +0200, Christoph Hellwig wrote:
> We need to make sure we have no outstanding COW blocks before we swap
> extents, as there is nothing preventing us from having COW preallocations
> on an inode that swapext is called on. That case can easily be
> reproduced by the upcoming always_cow mode.
>
Why? Is the current code to swap the cow forks not sufficient or
problematic in some way?
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/xfs/xfs_bmap_util.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 414dbc31139c..e0e9cbc98ccd 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -1515,6 +1515,12 @@ xfs_swap_extent_flush(
> return error;
> truncate_pagecache_range(VFS_I(ip), 0, -1);
>
> + if (xfs_inode_has_cow_data(ip)) {
> + error = xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true);
> + if (error)
> + return error;
> + }
> +
The change seems fine, but doesn't this make the follow on code to swap
the cow blocks tags spurious..?
Brian
> /* Verify O_DIRECT for ftmp */
> if (VFS_I(ip)->i_mapping->nrpages)
> return -EINVAL;
> --
> 2.18.0
>
next prev parent reply other threads:[~2018-09-27 21:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 14:42 more reflink fixes & debug Christoph Hellwig
2018-09-20 14:42 ` [PATCH 1/5] xfs: cancel COW blocks before swapext Christoph Hellwig
2018-09-20 20:04 ` Darrick J. Wong
2018-09-27 15:07 ` Brian Foster [this message]
2018-09-30 22:50 ` Christoph Hellwig
2018-10-01 11:03 ` Brian Foster
2018-09-20 14:42 ` [PATCH 2/5] xfs: skip delalloc COW blocks in xfs_reflink_end_cow Christoph Hellwig
2018-09-20 20:22 ` Darrick J. Wong
2018-09-20 14:42 ` [PATCH 3/5] xfs: fix fork selection in xfs_find_trim_cow_extent Christoph Hellwig
2018-09-20 14:42 ` [PATCH 4/5] xfs: print dangling delalloc extents Christoph Hellwig
2018-09-20 20:06 ` Darrick J. Wong
2018-09-27 15:07 ` Brian Foster
2018-09-20 14:42 ` [PATCH 5/5] xfs: introduce an always_cow mode Christoph Hellwig
2018-09-20 20:17 ` Darrick J. Wong
2018-09-20 21:23 ` Dave Chinner
2018-09-21 5:23 ` Christoph Hellwig
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