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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Oct 19, 2017 at 11:24:04PM -0600, Ross Zwisler wrote:
> 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@xxxxxxxxxxxxxxx>
> ---

Ok this is just my ignorance of how DAX works shining through, but do we need a
new flag to indicate this is DAX data?  You are logging it like it's just normal
data going to a certain sector, is that good enough?  If it is then hooray this
looks fine to me, I'm just slightly confused.  Thanks,

Josef



[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux