Re: [PATCH] btrfs: test checksum handling for clone, dedupe and swap on NOCOW files

在 2026/7/13 00:07, Daan De Meyer via B4 Relay 写道:
> From: Daan De Meyer <[email protected]>
> 
> Add two tests covering how checksummed and NOCOW extents interact.
> 
> btrfs/348 verifies that checksummed extents can be cloned and
> deduplicated into NOCOW files, and that the reverse direction stays
> rejected because NOCOW extents do not have checksums.

I strongly doubt if you have run the test btrfs/348.

As a very basic reflink clone from a datasum inode into nodatasum inode 
will cause btrfs check errors, with your kernel patch applied:

  # mkfs.btrfs -f $dev
  # mount $dev $mnt
  # xfs_io -f -c "pwrite 0 64k" -c sync $mnt/file1
  # mount -o remount,nodatasum $mnt
  # touch $mnt/file2
  # xfs_io -c "reflink $mnt/file1" $mnt/file2
  # umount $mnt
  # btrfs check $dev
Opening filesystem to check...
Checking filesystem on /dev/test/scratch1
UUID: efcb3cdd-5dd9-416d-89ac-33071c59c9e7
[1/8] checking log skipped (none written)
[2/8] checking root items
[3/8] checking extents
[4/8] checking free space tree
[5/8] checking fs roots
root 5 inode 258 errors 800, odd csum item
ERROR: errors found in fs roots
found 229376 bytes used, error(s) found

> 
> btrfs/349 verifies that a NOCOW swap file containing a checksummed
> extent is rejected even after the checksummed source is deleted and the
> extent is no longer shared.
> 
> Signed-off-by: Daan De Meyer <[email protected]>
> ---
> These tests cover the kernel series available at:
> https://lore.kernel.org/linux-btrfs/[email protected]/
> ---
>   tests/btrfs/348     | 180 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>   tests/btrfs/348.out |   2 +
>   tests/btrfs/349     |  73 +++++++++++++++++++++
>   tests/btrfs/349.out |   2 +
>   4 files changed, 257 insertions(+)
> 
> diff --git a/tests/btrfs/348 b/tests/btrfs/348
> new file mode 100755
> index 00000000..4faf994e
> --- /dev/null
> +++ b/tests/btrfs/348
> @@ -0,0 +1,180 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Daan De Meyer. All Rights Reserved.
> +#
> +# FS QA Test 348
> +#
> +# Verify that checksummed extents can be cloned and deduplicated into NOCOW
> +# files.  The reverse direction must remain rejected because NOCOW extents do
> +# not have checksums.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick clone dedupe scrub
> +
> +. ./common/reflink
> +
> +_require_scratch_reflink
> +_require_scratch_dedupe
> +_require_chattr C
> +_require_btrfs_no_nodatacow
> +_require_btrfs_no_nodatasum
> +_require_btrfs_command inspect-internal dump-tree
> +
> +_fixed_by_kernel_commit 28ce1d263f4d \
> +	"btrfs: allow reflinking from checksummed files into nodatasum files"

Nope, this is not a fix, nor the commit is upstreamed.

A proper test case should detect older kernels and skip if it doesn't 
support a new feature.