On Thu, Oct 26, 2017 at 07:59:39AM +0300, Amir Goldstein wrote:

On Wed, Oct 25, 2017 at 11:47 PM, Ross Zwisler
[off-list ref] wrote:

quoted

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 <redacted>

---

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...

Ah, yep, that's the version number that I submitted but Mike changed it to
v1.1.0 in his tree.  Here's the patch that was merged for v4.15-rc1:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers?id=98d82f48f1983ceef5c8d2f6c87bfee2918790ee

quoted

---
 .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

Yep, this is nicer.  Fixed.

Thanks for the review.