Re: [PATCH] xfs: Check if a direct write can result in a false ENOSPC error

[Chandan Babu R <chandan.babu@oracle.com>]

On Tue, Aug 23, 2022 at 07:28:30 AM -0700, Darrick J. Wong wrote:
> On Tue, Aug 23, 2022 at 02:34:33PM +0530, Chandan Babu R wrote:
>> This commit adds a test to check if a direct write on a delalloc extent
>> present in CoW fork can result in a false ENOSPC error. The bug has been fixed
>> by upstream commit d62113303d691 ("xfs: Fix false ENOSPC when performing
>> direct write on a delalloc extent in cow fork").
>> 
>> Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
>> ---
>>  tests/xfs/553     | 63 +++++++++++++++++++++++++++++++++++++++++++++++
>>  tests/xfs/553.out |  9 +++++++
>>  2 files changed, 72 insertions(+)
>>  create mode 100755 tests/xfs/553
>>  create mode 100644 tests/xfs/553.out
>> 
>> diff --git a/tests/xfs/553 b/tests/xfs/553
>> new file mode 100755
>> index 00000000..78ed0995
>> --- /dev/null
>> +++ b/tests/xfs/553
>> @@ -0,0 +1,63 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (c) 2022 Oracle.  All Rights Reserved.
>> +#
>> +# FS QA Test 553
>> +#
>> +# Test to check if a direct write on a delalloc extent present in CoW fork can
>> +# result in an ENOSPC error.
>> +#
>> +. ./common/preamble
>> +_begin_fstest auto quick clone
>> +
>> +# Import common functions.
>> +. ./common/reflink
>> +. ./common/inject
>> +
>> +# real QA test starts here
>> +_supported_fs xfs
>> +_fixed_by_kernel_commit d62113303d691 \
>> +	"xfs: Fix false ENOSPC when performing direct write on a delalloc extent in cow fork"
>> +_require_scratch_reflink
>> +_require_xfs_debug
>> +_require_test_program "punch-alternating"
>> +_require_xfs_io_error_injection "bmap_alloc_minlen_extent"
>> +_require_xfs_io_command "reflink"
>> +_require_xfs_io_command "cowextsize"
>> +
>> +source=${SCRATCH_MNT}/source
>> +destination=${SCRATCH_MNT}/destination
>> +fragmented_file=${SCRATCH_MNT}/fragmented_file
>> +
>> +echo "Format and mount fs"
>> +_scratch_mkfs >> $seqres.full
>> +_scratch_mount >> $seqres.full
>> +
>> +echo "Create source file"
>> +$XFS_IO_PROG -f -c "pwrite 0 32M" $source >> $seqres.full
>> +
>> +echo "Reflink destination file with source file"
>> +$XFS_IO_PROG -f -c "reflink $source" $destination >> $seqres.full
>> +
>> +echo "Set destination file's cowextsize"
>> +$XFS_IO_PROG -c "cowextsize 16M" $destination >> $seqres.full
>> +
>> +echo "Fragment FS"
>> +$XFS_IO_PROG -f -c "pwrite 0 64M" $fragmented_file >> $seqres.full
>> +sync
>> +$here/src/punch-alternating $fragmented_file >> $seqres.full
>> +
>> +echo "Inject bmap_alloc_minlen_extent error tag"
>> +_scratch_inject_error bmap_alloc_minlen_extent 1
>> +
>> +echo "Create 16MiB delalloc extent in destination file's CoW fork"
>> +$XFS_IO_PROG -c "pwrite 0 4k" $destination >> $seqres.full
>> +
>> +sync
>> +
>> +echo "Direct I/O write at 12k file offset in destination file"
>> +$XFS_IO_PROG -d -c "pwrite 12k 8k" $destination >> $seqres.full
>
> Does this still work if the blocksize is 64k? ;)
>

Thanks for pointing that out. I will convert the script to use file blocks as
units rather than bytes.

-- 
chandan