Re: [fstests PATCH v3] generic: add test for DAX MAP_SYNC support

Amir Goldstein
2017-10-26T04:59:41Z

On Wed, Oct 25, 2017 at 11:47 PM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> Add a test that exercises DAX's new MAP_SYNC flag.
>
> This test creates a file and writes to it via an mmap(), but never syncs
> via fsync/msync. This process is tracked via dm-log-writes, then replayed.
>
> If MAP_SYNC is working the dm-log-writes replay will show the test file
> with 1MiB of on-media block allocations. This is because each allocating
> page fault included an implicit metadata sync. If MAP_SYNC isn't working
> (which you can test by fiddling with the parameters to mmap()) the file
> will be smaller or missing entirely.
>
> Note that dm-log-writes doesn't track the data that we write via the
> mmap(), so we can't do any data integrity checking. We can only verify
> that the metadata writes for the page faults happened.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>
> ---
>
> Changes since v2:
> - Fixed _require_log_writes() so that DAX will be disallowed if the
> version of the dm-log-writes target is older than v1.1.0. (Amir)

It seems like your kernel patch bumped the version to 1.0.1...

>
> ---
> .gitignore | 1 +
> common/dmlogwrites | 4 ++-
> common/rc | 6 ++--
> src/Makefile | 3 +-
> src/t_map_sync.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/generic/466 | 76 ++++++++++++++++++++++++++++++++++++++++++
> tests/generic/466.out | 3 ++
> tests/generic/group | 1 +
> 8 files changed, 182 insertions(+), 4 deletions(-)
> create mode 100644 src/t_map_sync.c
> create mode 100755 tests/generic/466
> create mode 100644 tests/generic/466.out
>
> diff --git a/.gitignore b/.gitignore
> index 2014c08..9fc0695 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -119,6 +119,7 @@
> /src/t_getcwd
> /src/t_holes
> /src/t_immutable
> +/src/t_map_sync
> /src/t_mmap_cow_race
> /src/t_mmap_dio
> /src/t_mmap_fallocate
> diff --git a/common/dmlogwrites b/common/dmlogwrites
> index 247c744..71d008d 100644
> --- a/common/dmlogwrites
> +++ b/common/dmlogwrites
> @@ -23,8 +23,10 @@ _require_log_writes()
> [ -z "$LOGWRITES_DEV" -o ! -b "$LOGWRITES_DEV" ] && \
> _notrun "This test requires a valid \$LOGWRITES_DEV"
>
> - _exclude_scratch_mount_option dax
> _require_dm_target log-writes
> + if [[ ${DMTARGET_VER[0]} == 1 && ${DMTARGET_VER[1]} < 1 ]]; then
> + _exclude_scratch_mount_option dax
> + fi

IMO, this would be better as:

local z=0
_scratch_has_mount_option dax && z=1
_require_dm_target log-writes 1 0 $z

Or something like that