On Sun, Sep 25, 2016 at 07:18:37PM -0600, Stephen Bates wrote: > The documentation for dax is not up to date with respect to the struct > page support available in some of the device drivers that utilize > it. > > Signed-off-by: Stephen Bates <sbates@xxxxxxxxxxxx> Great, thanks for updating this. Acked-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > --- > Documentation/filesystems/dax.txt | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt > index 0c16a22..23d18b8 100644 > --- a/Documentation/filesystems/dax.txt > +++ b/Documentation/filesystems/dax.txt > @@ -123,9 +123,12 @@ The DAX code does not work correctly on architectures which have virtually > mapped caches such as ARM, MIPS and SPARC. > > Calling get_user_pages() on a range of user memory that has been mmaped > -from a DAX file will fail as there are no 'struct page' to describe > -those pages. This problem is being worked on. That means that O_DIRECT > -reads/writes to those memory ranges from a non-DAX file will fail (note > -that O_DIRECT reads/writes _of a DAX file_ do work, it is the memory > -that is being accessed that is key here). Other things that will not > -work include RDMA, sendfile() and splice(). > +from a DAX file will fail when there are no 'struct page' to describe > +those pages. This problem has been addressed in some device drivers > +by adding optional struct page support for pages under the control of > +the driver (see CONFIG_NVDIMM_PFN in drivers/nvdimm for an example of > +how to do this). In the non struct page cases O_DIRECT reads/writes to > +those memory ranges from a non-DAX file will fail (note that O_DIRECT > +reads/writes _of a DAX file_ do work, it is the memory that is being > +accessed that is key here). Other things that will not work in the > +non struct page case include RDMA, sendfile() and splice(). > -- > 2.5.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
