Re: [PATCH v2] btrfs: add a test for defrag of contiguous file extents

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2024/10/30 18:20, fdmanana@kernel.org 写道:
> From: Filipe Manana <fdmanana@suse.com>
>
> Test that defrag merges adjacent extents that are contiguous.
> This exercises a regression fixed by a patchset for the kernel that is
> comprissed of the following patches:
>
>    btrfs: fix extent map merging not happening for adjacent extents
>    btrfs: fix defrag not merging contiguous extents due to merged extent maps
>
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu
> ---
>
> V2: Fix typo (treshold -> threshold), make the test be skipped if compression
>      is enabled.
>
>   tests/btrfs/325     | 83 +++++++++++++++++++++++++++++++++++++++++++++
>   tests/btrfs/325.out | 22 ++++++++++++
>   2 files changed, 105 insertions(+)
>   create mode 100755 tests/btrfs/325
>   create mode 100644 tests/btrfs/325.out
>
> diff --git a/tests/btrfs/325 b/tests/btrfs/325
> new file mode 100755
> index 00000000..48470509
> --- /dev/null
> +++ b/tests/btrfs/325
> @@ -0,0 +1,83 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2024 SUSE Linux Products GmbH. All Rights Reserved.
> +#
> +# FS QA Test 325
> +#
> +# Test that defrag merges adjacent extents that are contiguous.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick preallocrw defrag
> +
> +. ./common/filter
> +
> +_require_scratch
> +_require_btrfs_command inspect-internal dump-tree
> +_require_xfs_io_command "falloc"
> +# We want to test getting a 256K extent after defrag, so skip the test if
> +# compression is enabled (with compression the maximum extent size is 128K).
> +_require_no_compress
> +
> +_fixed_by_kernel_commit xxxxxxxxxxxx \
> +	"btrfs: fix extent map merging not happening for adjacent extents"
> +_fixed_by_kernel_commit xxxxxxxxxxxx \
> +	"btrfs: fix defrag not merging contiguous extents due to merged extent maps"
> +
> +count_file_extent_items()
> +{
> +	# We count file extent extent items through dump-tree instead of using
> +	# fiemap because fiemap merges adjacent extent items when they are
> +	# contiguous.
> +	# We unmount because all metadata must be ondisk for dump-tree to see
> +	# it and work correctly.
> +	_scratch_unmount
> +	$BTRFS_UTIL_PROG inspect-internal dump-tree -t 5 $SCRATCH_DEV | \
> +		grep EXTENT_DATA | wc -l
> +	_scratch_mount
> +}
> +
> +_scratch_mkfs >>$seqres.full 2>&1 || _fail "mkfs failed"
> +_scratch_mount
> +
> +# Create a file with a size of 256K and 4 written extents of 64K each.
> +# We fallocate to guarantee exact extent size, even if compression mount
> +# option is give, and write to them because defrag skips prealloc extents.
> +$XFS_IO_PROG -f -c "falloc 0 64K" \
> +	     -c "pwrite -S 0xab 0 64K" \
> +	     -c "falloc 64K 64K" \
> +	     -c "pwrite -S 0xcd 64K 64K" \
> +	     -c "falloc 128K 64K" \
> +	     -c "pwrite -S 0xef 128K 64K" \
> +	     -c "falloc 192K 64K" \
> +	     -c "pwrite -S 0x73 192K 64K" \
> +	     $SCRATCH_MNT/foo | _filter_xfs_io
> +
> +echo -n "Initial number of file extent items: "
> +count_file_extent_items
> +
> +# Read the whole file in order to load extent maps and merge them.
> +cat $SCRATCH_MNT/foo > /dev/null
> +
> +# Now defragment with a threshold of 128K. After this we expect to get a file
> +# with 1 file extent item - the threshold is 128K but since all the extents are
> +# contiguous, they should be merged into a single one of 256K.
> +$BTRFS_UTIL_PROG filesystem defragment -t 128K $SCRATCH_MNT/foo
> +echo -n "Number of file extent items after defrag with 128K threshold: "
> +count_file_extent_items
> +
> +# Read the whole file in order to load extent maps and merge them.
> +cat $SCRATCH_MNT/foo > /dev/null
> +
> +# Now defragment with a threshold of 256K. After this we expect to get a file
> +# with only 1 file extent item.
> +$BTRFS_UTIL_PROG filesystem defragment -t 256K $SCRATCH_MNT/foo
> +echo -n "Number of file extent items after defrag with 256K threshold: "
> +count_file_extent_items
> +
> +# Check that the file has the expected data, that defrag didn't cause any data
> +# loss or corruption.
> +echo "File data after defrag:"
> +_hexdump $SCRATCH_MNT/foo
> +
> +status=0
> +exit
> diff --git a/tests/btrfs/325.out b/tests/btrfs/325.out
> new file mode 100644
> index 00000000..c0df8137
> --- /dev/null
> +++ b/tests/btrfs/325.out
> @@ -0,0 +1,22 @@
> +QA output created by 325
> +wrote 65536/65536 bytes at offset 0
> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +wrote 65536/65536 bytes at offset 65536
> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +wrote 65536/65536 bytes at offset 131072
> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +wrote 65536/65536 bytes at offset 196608
> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +Initial number of file extent items: 4
> +Number of file extent items after defrag with 128K threshold: 1
> +Number of file extent items after defrag with 256K threshold: 1
> +File data after defrag:
> +000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab  >................<
> +*
> +010000 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd  >................<
> +*
> +020000 ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef  >................<
> +*
> +030000 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73  >ssssssssssssssss<
> +*
> +040000