Re: [PATCH] generic: test zero-byte writes to new file

["Nirjhar Roy (IBM)" <nirjhar.roy.lists@gmail.com>]

On 2/21/25 22:17, Darrick J. Wong wrote:
> On Fri, Feb 21, 2025 at 10:44:09AM +0530, Nirjhar Roy (IBM) wrote:
>> On Thu, 2025-02-13 at 12:06 -0600, Eric Sandeen wrote:
>>> A bug was recently fixed in exfat where attempting to do a zero-byte
>>> write would yield -EFAULT; test for that here.
>>>
>>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>>> ---
>>>
>>> diff --git a/tests/generic/761 b/tests/generic/761
>>> new file mode 100755
>>> index 00000000..e933eb83
>>> --- /dev/null
>>> +++ b/tests/generic/761
>>> @@ -0,0 +1,28 @@
>>> +#! /bin/bash
>>> +# SPDX-License-Identifier: GPL-2.0
>>> +# Copyright (c) 2025 Red Hat, Inc.  All Rights Reserved.
>>> +#
>>> +# FS QA Test 761
>>> +#
>>> +# test zero-byte writes
>>> +#
>>> +# exfat had a regression where a zero-byte write to a file would
>>> +# yield -EfAULT. Should work on all filesystems - write should
>>> +# succeed and the zero-byte file should be created.
>>> +#
>>> +. ./common/preamble
>>> +_begin_fstest auto quick
>>> +
>>> +[ "$FSTYP" = "exfat" ] && _fixed_by_kernel_commit dda0407a2026 \
>>> +	"exfat: short-circuit zero-byte writes in
>>> exfat_file_write_iter"
>>> +
>>> +# Modify as appropriate.
>>> +_require_test
>>> +
>>> +rm -f $TEST_DIR/testfile.$seq
>>> +$XFS_IO_PROG -f -c "pwrite 0 0" $TEST_DIR/testfile.$seq
>>> +test -f $TEST_DIR/testfile.$seq || _fail "file not created"
>> Minor: Maybe just remove the test file that is created above (since we
>> are using the TEST_DIR)and not leave any test artifacts? Or, maybe use
>> the scratch device?
> Agreed, the _cleanup should remove the testfile.
>
> Using the scratch device (== additional runtime for mkfs) is overkill
> since this test creates a single file but writes nothing to it.

Yes, makes sense.

--NR

>
> --D
>
>> --NR
>>> +
>>> +# success, all done
>>> +status=0
>>> +exit
>>> diff --git a/tests/generic/761.out b/tests/generic/761.out
>>> new file mode 100644
>>> index 00000000..72ebba4c
>>> --- /dev/null
>>> +++ b/tests/generic/761.out
>>> @@ -0,0 +1,2 @@
>>> +QA output created by 761
>>> +Silence is golden
>>>
>>
-- 
Nirjhar Roy
Linux Kernel Developer
IBM, Bangalore