Thread (19 messages) 19 messages, 5 authors, 2017-11-16

Re: [PATCH 2/2] dm log writes: add support for DAX

From: Ross Zwisler <hidden>
Date: 2017-10-24 19:30:25
Also in: dm-devel, linux-fsdevel, linux-raid, linux-xfs, lkml, nvdimm

On Tue, Oct 24, 2017 at 03:22:23PM -0400, Mike Snitzer wrote:
On Fri, Oct 20 2017 at  1:24am -0400,
Ross Zwisler [off-list ref] wrote:
quoted
Now that we have the ability log filesystem writes using a flat buffer, add
support for DAX.  Unfortunately we can't easily track data that has been
written via mmap() now that the dax_flush() abstraction was removed by this
commit:

commit c3ca015fab6d ("dax: remove the pmem_dax_ops->flush abstraction")

Otherwise we could just treat each flush as a big write, and store the data
that is being synced to media.  It may be worthwhile to add the dax_flush()
entry point back, just as a notifier so we can do this logging.

The motivation for this support is the need for an xfstest that can test
the new MAP_SYNC DAX flag.  By logging the filesystem activity with
dm-log-writes we can show that the MAP_SYNC page faults are writing out
their metadata as they happen, instead of requiring an explicit
msync/fsync.

Signed-off-by: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
I've picked this up, please see:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-4.15/dm&id=ae613bbb0144e84cb3c0ebfa9f4fd4d1507c2f0e

I tweaked the header and tweaked a couple whitespace nits.  Also
switched version bump from 1.0.1 to 1.1.0.

Thanks,
Mike
Sure, your tweaks look fine.  Thanks!
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