On Mon, Apr 13, 2020 at 9:38 PM Ira Weiny <ira.weiny@xxxxxxxxx> wrote: > > On Mon, Apr 13, 2020 at 09:19:12AM -0700, Darrick J. Wong wrote: > > On Sun, Apr 12, 2020 at 10:40:46PM -0700, ira.weiny@xxxxxxxxx wrote: > > > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > > > > > Update the Usage section to reflect the new individual dax selection > > > functionality. > > > > Yum. :) > > > > > Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> > > > > > > --- > > > Changes from V6: > > > Update to allow setting FS_XFLAG_DAX any time. > > > Update with list of behaviors from Darrick > > > https://lore.kernel.org/lkml/20200409165927.GD6741@magnolia/ > > > > > > Changes from V5: > > > Update to reflect the agreed upon semantics > > > https://lore.kernel.org/lkml/20200405061945.GA94792@xxxxxxxxxxxxxxxxxxxxxxxxx/ > > > --- > > > Documentation/filesystems/dax.txt | 166 +++++++++++++++++++++++++++++- > > > 1 file changed, 163 insertions(+), 3 deletions(-) > > > > > > diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt > > > index 679729442fd2..af14c1b330a9 100644 > > > --- a/Documentation/filesystems/dax.txt > > > +++ b/Documentation/filesystems/dax.txt > > > @@ -17,11 +17,171 @@ For file mappings, the storage device is mapped directly into userspace. > > > Usage > > > ----- > > > > > > -If you have a block device which supports DAX, you can make a filesystem > > > +If you have a block device which supports DAX, you can make a file system > > > on it as usual. The DAX code currently only supports files with a block > > > size equal to your kernel's PAGE_SIZE, so you may need to specify a block > > > -size when creating the filesystem. When mounting it, use the "-o dax" > > > -option on the command line or add 'dax' to the options in /etc/fstab. > > > +size when creating the file system. > > > + > > > +Currently 2 filesystems support DAX, ext4 and xfs. Enabling DAX on them is > > > +different at this time. > > > > I thought ext2 supports DAX? > > Not that I know of? Does it? Yes. Seemed like a good idea at the time, but in retrospect... In fairness I believe this was also an olive branch to XIP users that were transitioned to DAX, so they did not also need to transition filesystems.
