Re: [fstests PATCH v2] generic: add test for DAX MAP_SYNC support

Ross Zwisler
2017-10-25T17:12:28Z

On Wed, Oct 25, 2017 at 03:19:22PM +0300, Amir Goldstein wrote:
> On Sun, Oct 22, 2017 at 9:56 AM, Amir Goldstein <amir73il@gmail.com> wrote:
> > On Sat, Oct 21, 2017 at 12:25 AM, 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 v1:
> >> - Addressed review feedback from Amir. Thank you for the review!
> >
> > Looks good.
> >
> >>
> >> ---
> >> .gitignore | 1 +
> >> common/dmlogwrites | 1 -
> >> src/Makefile | 3 +-
> >> src/t_map_sync.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++
> >> tests/generic/466 | 76 ++++++++++++++++++++++++++++++++++++++++++
> >> tests/generic/466.out | 3 ++
> >> tests/generic/group | 1 +
> >> 7 files changed, 175 insertions(+), 2 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..5b57df9 100644
> >> --- a/common/dmlogwrites
> >> +++ b/common/dmlogwrites
> >> @@ -23,7 +23,6 @@ _require_log_writes()
> >> [ -z "$LOGWRITES_DEV" -o ! -b "$LOGWRITES_DEV" ] && \
> >> _notrun "This test requires a valid \$LOGWRITES_DEV"
> >>
> >> - _exclude_scratch_mount_option dax
>
> Wait. It this really ok to relax no dax from _require_log_writes()?
> Shouldn't you check log-write target version or something to verify
> that log-writes+dax is really supported?
> I think you should.

Ah, yep, that makes sense. I'll update for v3.