On Mon, Feb 26, 2024 at 06:02:37PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> On a higly fragmented filesystem a Direct IO write can fail with -ENOSPC error
> even though the filesystem has sufficient number of free blocks.
>
> This occurs if the file offset range on which the write operation is being
> performed has a delalloc extent in the cow fork and this delalloc extent
> begins much before the Direct IO range.
>
> In such a scenario, xfs_reflink_allocate_cow() invokes xfs_bmapi_write() to
> allocate the blocks mapped by the delalloc extent. The extent thus allocated
> may not cover the beginning of file offset range on which the Direct IO write
> was issued. Hence xfs_reflink_allocate_cow() ends up returning -ENOSPC.
>
> This test addresses this issue.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> common/rc | 14 +++++++++
> tests/xfs/1923 | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/xfs/1923.out | 8 +++++
> 3 files changed, 107 insertions(+)
> create mode 100755 tests/xfs/1923
> create mode 100644 tests/xfs/1923.out
>
>
> diff --git a/common/rc b/common/rc
> index 30c44dddd9..d3a2a0718b 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -1873,6 +1873,20 @@ _require_scratch_delalloc()
> _scratch_unmount
> }
>
> +# Require test fs supports delay allocation.
> +_require_test_delalloc()
> +{
> + _require_command "$FILEFRAG_PROG" filefrag
> +
> + rm -f $TEST_DIR/testy
> + $XFS_IO_PROG -f -c 'pwrite 0 64k' $TEST_DIR/testy &> /dev/null
> + $FILEFRAG_PROG -v $TEST_DIR/testy 2>&1 | grep -q delalloc
I'm wondering if it's a 100% reliable way to get the "delalloc" flag when
the delalloc is supported? If not, is it worth testing with several files
or a loop, then return 0 if one of them get delalloc ?
> + res=$?
> + rm -f $TEST_DIR/testy
> + test $res -eq 0 || \
> + _notrun "test requires delayed allocation buffered writes"
> +}
> +
> # this test needs a test partition - check we're ok & mount it
> #
> _require_test()
> diff --git a/tests/xfs/1923 b/tests/xfs/1923
> new file mode 100755
> index 0000000000..4e494ad8c2
> --- /dev/null
> +++ b/tests/xfs/1923
> @@ -0,0 +1,85 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2022-2024 Oracle. All Rights Reserved.
> +#
> +# FS QA Test No. 1923
> +#
> +# This is a regression test for "xfs: Fix false ENOSPC when performing direct
> +# write on a delalloc extent in cow fork". If there is a lot of free space but
> +# it is very fragmented, it's possible that a very large delalloc reservation
> +# could be created in the CoW fork by a buffered write. If a directio write
> +# tries to convert the delalloc reservation to a real extent, it's possible
> +# that the allocation will succeed but fail to convert even the first block of
> +# the directio write range. In this case, XFS will return ENOSPC even though
> +# all it needed to do was to keep converting until the allocator returns ENOSPC
> +# or the first block of the direct write got some space.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick clone
> +
> +_cleanup()
> +{
> + cd /
> + rm -f $file1 $file2 $fragmentedfile
> +}
> +
> +# Import common functions.
> +. ./common/reflink
> +. ./common/inject
> +
> +# real QA test starts here
> +_fixed_by_kernel_commit XXXXX \
> + "xfs: Fix false ENOSPC when performing direct write on a delalloc extent in cow fork"
Is it this commit below, or a new fix with same subject?
commit d62113303d691bcd8d0675ae4ac63e7769afc56c
Author: Chandan Babu R <chandan.babu@xxxxxxxxxx>
Date: Thu Aug 4 08:59:27 2022 -0700
xfs: Fix false ENOSPC when performing direct write on a delalloc extent in cow fork
If it's an old commit, please replace the "XXXXX" to "d62113303d69".
> +
> +# Modify as appropriate.
> +_supported_fs generic
"xfs"? As it's in tests/xfs/ directory.
> +_require_test_program "punch-alternating"
> +_require_test_reflink
> +_require_xfs_io_error_injection "bmap_alloc_minlen_extent"
> +_require_test_delalloc
> +
> +file1=$TEST_DIR/file1.$seq
> +file2=$TEST_DIR/file2.$seq
> +fragmentedfile=$TEST_DIR/fragmentedfile.$seq
As you use the $TEST_DIR, it might be worth making sure these files
aren't existed. Due to the files (from other cases) in $TEST_DIR might
not be cleaned, especially if they don't take much free space.
So if these 3 files won't take much space, we can keep them, don't need
a specific _cleanup(). And move the "rm -f $file1 $file2 $fragmentedfile"
at here.
> +
> +# COW operates on pages, so we must not perform operations in units smaller
> +# than a page.
> +blksz=$(_get_file_block_size $TEST_DIR)
> +pagesz=$(_get_page_size)
> +if (( $blksz < $pagesz )); then
> + blksz=$pagesz
> +fi
Just curious, this's a xfs specific test case, can xfs support blocksize >
pagesize? If not, can we just use pagesz directly at here ?
> +
> +echo "Create source file"
> +$XFS_IO_PROG -f -c "pwrite 0 $((blksz * 256))" $file1 >> $seqres.full
> +
> +sync
> +
> +echo "Create Reflinked file"
> +_cp_reflink $file1 $file2 >> $seqres.full
> +#$XFS_IO_PROG -f -c "reflink $file1" $file2 >> $seqres.full
There's a "#", do you hope to run it or not?
> +
> +echo "Set cowextsize"
> +$XFS_IO_PROG -c "cowextsize $((blksz * 128))" -c stat $file1 >> $seqres.full
> +
> +echo "Fragment FS"
> +$XFS_IO_PROG -f -c "pwrite 0 $((blksz * 512))" $fragmentedfile >> $seqres.full
> +sync
> +$here/src/punch-alternating $fragmentedfile
> +
> +echo "Allocate block sized extent from now onwards"
> +_test_inject_error bmap_alloc_minlen_extent 1
> +
> +echo "Create big delalloc extent in CoW fork"
> +$XFS_IO_PROG -c "pwrite 0 $blksz" $file1 >> $seqres.full
> +
> +sync
> +
> +$XFS_IO_PROG -c 'bmap -elpv' -c 'bmap -celpv' $file1 >> $seqres.full
> +
> +echo "Direct I/O write at offset 3FSB"
> +$XFS_IO_PROG -d -c "pwrite $((blksz * 3)) $((blksz * 2))" $file1 >> $seqres.full
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/xfs/1923.out b/tests/xfs/1923.out
> new file mode 100644
> index 0000000000..a0553cf3ee
> --- /dev/null
> +++ b/tests/xfs/1923.out
> @@ -0,0 +1,8 @@
> +QA output created by 1923
> +Create source file
> +Create Reflinked file
> +Set cowextsize
> +Fragment FS
> +Allocate block sized extent from now onwards
> +Create big delalloc extent in CoW fork
> +Direct I/O write at offset 3FSB
>
