Re: [PATCH v2 1/1] generic: test reads racing with slow reflink operations

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On Sat, Nov 11, 2023 at 02:22:57PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
> 
> XFS has a rather slow reflink operation.  While a reflink operation is
> running, other programs cannot read the contents of the source file,
> which is causing latency spikes.  Catherine Hoang wrote a patch to
> permit reads, since the source file contents do not change.  This is a
> functionality test for that patch.
> 
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Catherine Hoang <catherine.hoang@xxxxxxxxxx>
> ---
> v2: fix a couple of things pointed out by zorro
> ---
>  configure.ac              |    1 
>  include/builddefs.in      |    1 
>  m4/package_libcdev.m4     |   13 ++
>  src/Makefile              |    4 +
>  src/t_reflink_read_race.c |  339 +++++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/1953        |   75 ++++++++++
>  tests/generic/1953.out    |    6 +
>  tests/xfs/1872            |   10 +
>  tests/xfs/1873            |   10 +

This xfs/1953 looks good to me, but about the changes on xfs/1872 and 1873, I think
those might be another patch :)

>  9 files changed, 447 insertions(+), 12 deletions(-)
>  create mode 100644 src/t_reflink_read_race.c
>  create mode 100755 tests/generic/1953
>  create mode 100644 tests/generic/1953.out
> 

[snip]

> diff --git a/tests/generic/1953 b/tests/generic/1953
> new file mode 100755
> index 0000000000..70aefc736b
> --- /dev/null
> +++ b/tests/generic/1953
> @@ -0,0 +1,75 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2023, Oracle and/or its affiliates.  All Rights Reserved.
> +#
> +# FS QA Test No. 1953
> +#
> +# Race file reads with a very slow reflink operation to see if the reads
> +# actually complete while the reflink is ongoing.  This is a functionality
> +# test for XFS commit f3ba4762fa56 "xfs: allow read IO and FICLONE to run
> +# concurrently".
> +#
> +. ./common/preamble
> +_begin_fstest auto clone punch
> +
> +# Import common functions.
> +. ./common/filter
> +. ./common/attr
> +. ./common/reflink
> +
> +# real QA test starts here
> +_require_scratch_reflink
> +_require_cp_reflink
> +_require_xfs_io_command "fpunch"
> +_require_test_program "punch-alternating"
> +_require_test_program "t_reflink_read_race"
> +_require_command "$TIMEOUT_PROG" timeout
> +
> +rm -f "$seqres.full"
> +
> +echo "Format and mount"
> +_scratch_mkfs > "$seqres.full" 2>&1
> +_scratch_mount >> "$seqres.full" 2>&1
> +
> +testdir="$SCRATCH_MNT/test-$seq"
> +mkdir "$testdir"
> +
> +calc_space() {
> +	blocks_needed=$(( 2 ** (fnr + 1) ))
> +	space_needed=$((blocks_needed * blksz * 5 / 4))
> +}
> +
> +# Figure out the number of blocks that we need to get the reflink runtime above
> +# 1 seconds
> +echo "Create a many-block file"
> +for ((fnr = 1; fnr < 40; fnr++)); do
> +	free_blocks=$(stat -f -c '%a' "$testdir")
> +	blksz=$(_get_file_block_size "$testdir")
> +	space_avail=$((free_blocks * blksz))
> +	calc_space
> +	test $space_needed -gt $space_avail && \
> +		_notrun "Insufficient space for stress test; would only create $blocks_needed extents."
> +
> +	off=$(( (2 ** fnr) * blksz))
> +	$XFS_IO_PROG -f -c "pwrite -S 0x61 -b 4194304 $off $off" "$testdir/file1" >> "$seqres.full"
> +	"$here/src/punch-alternating" "$testdir/file1" >> "$seqres.full"
> +
> +	timeout 1s cp --reflink=always "$testdir/file1" "$testdir/garbage" || break

As there's `_require_command "$TIMEOUT_PROG" timeout`, so better to use $TIMEOUT_PROG
at here. I can help to change this, but the 1872 and 1873 need to be removed, they
block the patch merging.

Thanks,
Zorro

> +done
> +echo "fnr=$fnr" >> $seqres.full
> +
> +echo "Reflink the big file"
> +$here/src/t_reflink_read_race "$testdir/file1" "$testdir/file2" \
> +	"$testdir/outcome" &>> $seqres.full
> +
> +if [ ! -e "$testdir/outcome" ]; then
> +	echo "Could not set up program"
> +elif grep -q "finished read early" "$testdir/outcome"; then
> +	echo "test completed successfully"
> +else
> +	cat "$testdir/outcome"
> +fi
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/1953.out b/tests/generic/1953.out
> new file mode 100644
> index 0000000000..8eaacb7ff0
> --- /dev/null
> +++ b/tests/generic/1953.out
> @@ -0,0 +1,6 @@
> +QA output created by 1953
> +Format and mount
> +Create a many-block file
> +Reflink the big file
> +Terminated
> +test completed successfully
> diff --git a/tests/xfs/1872 b/tests/xfs/1872
> index 004e99176e..289fc99612 100755
> --- a/tests/xfs/1872
> +++ b/tests/xfs/1872
> @@ -10,15 +10,13 @@
>  . ./common/preamble
>  _begin_fstest auto quick unlink
>  
> -# Import common functions.
> -source ./common/filter
> -source ./common/fuzzy
> -source ./common/quota
> +. ./common/filter
> +. ./common/fuzzy
> +. ./common/quota
>  
>  # real QA test starts here
>  
> -# Modify as appropriate.
> -_supported_fs generic
> +_supported_fs xfs
>  _require_xfs_db_command iunlink
>  _require_scratch_nocheck	# we'll run repair ourselves
>  
> diff --git a/tests/xfs/1873 b/tests/xfs/1873
> index 46af16f5d1..5d9fc620dc 100755
> --- a/tests/xfs/1873
> +++ b/tests/xfs/1873
> @@ -10,15 +10,13 @@
>  . ./common/preamble
>  _begin_fstest auto online_repair
>  
> -# Import common functions.
> -source ./common/filter
> -source ./common/fuzzy
> -source ./common/quota
> +. ./common/filter
> +. ./common/fuzzy
> +. ./common/quota
>  
>  # real QA test starts here
>  
> -# Modify as appropriate.
> -_supported_fs generic
> +_supported_fs xfs
>  _require_xfs_db_command iunlink
>  # The iunlink bucket repair code wasn't added to the AGI repair code
>  # until after the directory repair code was merged
> 





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