| Message ID | 1474852717-2161-1-git-send-email-sbates@raithlin.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@raithlin.com> Great, thanks for updating this. Acked-by: Ross Zwisler <ross.zwisler@linux.intel.com> > --- > 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-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 27 Sep 2016 10:52:48 -0600 Ross Zwisler <ross.zwisler@linux.intel.com> wrote: > 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@raithlin.com> > > Great, thanks for updating this. > > Acked-by: Ross Zwisler <ross.zwisler@linux.intel.com> Applied to the docs tree, thanks. jon -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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().
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@raithlin.com> --- Documentation/filesystems/dax.txt | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)