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

Amir Goldstein
2017-10-25T12:19:23Z

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.

>> _require_dm_target log-writes
>> _require_test_program "log-writes/replay-log"
>> }