Looks good.
Reviewed-by: David Disseldorp <ddiss@xxxxxxx>
A few minor nits below...
On Wed, 22 Feb 2023 11:30:20 -0800, Boris Burkov wrote:
...
> + /* touch the first page of the mapping to bring it into cache */
> + c = ((char *)buf)[0];
> + printf("%u\n", c);
> +
> + do_dio(argv[2], buf, sz);
> +}
> diff --git a/tests/generic/708 b/tests/generic/708
> new file mode 100755
> index 00000000..ff2e162b
> --- /dev/null
> +++ b/tests/generic/708
> @@ -0,0 +1,48 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2023 Meta Platforms, Inc. All Rights Reserved.
> +#
> +# FS QA Test 708
> +#
> +# Test iomap direct_io partial writes.
> +#
> +# Create a reasonably large file, then run a program which mmaps it,
> +# touches the first page, then dio writes it to a second file. This
> +# can result in a page fault reading from the mmapped dio write buffer and
> +# thus the iompap direct_io partial write codepath.
s/iompap/iomap
> +#
> +. ./common/preamble
> +_begin_fstest quick auto
> +_fixed_by_kernel_commit XXXX 'btrfs: fix dio continue after short write due to buffer page fault'
> +
> +# Override the default cleanup function.
> +_cleanup()
> +{
> + cd /
> + rm -r -f $tmp.*
There's some whitespace damage on the two lines above.
> + rm -f $TEST_DIR/dio-buf-fault.*
> +}
> +
> +# Import common functions.
> +. ./common/filter
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs generic
> +_require_test
> +_require_odirect
> +_require_test_program dio-buf-fault
> +src=$TEST_DIR/dio-buf-fault.src
> +dst=$TEST_DIR/dio-buf-fault.dst
> +
> +echo "Silence is golden"
> +
> +$XFS_IO_PROG -fc "pwrite -q 0 $((2 * 1024 * 1024))" $src
> +sync
> +$here/src/dio-buf-fault $src $dst >> $seqres.full || _fail "failed doing the dio copy"
Any reason for redirecting the single character to the 708.full file? It
doesn't appear useful for debugging so can probably go to /dev/null
