On 25/07/04 01:47PM, Jonathan Cameron wrote:
> On Thu, 3 Jul 2025 13:50:18 -0500
> John Groves <John@xxxxxxxxxx> wrote:
>
> > Notes about this commit:
> >
> > * These methods are based on pmem_dax_ops from drivers/nvdimm/pmem.c
> >
> > * dev_dax_direct_access() is returns the hpa, pfn and kva. The kva was
> > newly stored as dev_dax->virt_addr by dev_dax_probe().
> >
> > * The hpa/pfn are used for mmap (dax_iomap_fault()), and the kva is used
> > for read/write (dax_iomap_rw())
> >
> > * dev_dax_recovery_write() and dev_dax_zero_page_range() have not been
> > tested yet. I'm looking for suggestions as to how to test those.
> >
> > Signed-off-by: John Groves <john@xxxxxxxxxx>
> A few trivial things noticed whilst reading through.
BTW thanks for looking at the dev_dax_iomap part of the series. These are
basically identical to the two standalone-famfs series' I put out last year,
but have IIRC not gotten review comments before this.
>
> > ---
> > drivers/dax/bus.c | 120 ++++++++++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 115 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> > index 9d9a4ae7bbc0..61a8d1b3c07a 100644
> > --- a/drivers/dax/bus.c
> > +++ b/drivers/dax/bus.c
> > @@ -7,6 +7,10 @@
> > #include <linux/slab.h>
> > #include <linux/dax.h>
> > #include <linux/io.h>
> > +#include <linux/backing-dev.h>
> > +#include <linux/pfn_t.h>
> > +#include <linux/range.h>
> > +#include <linux/uio.h>
> > #include "dax-private.h"
> > #include "bus.h"
> >
> > @@ -1441,6 +1445,105 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
> > }
> > EXPORT_SYMBOL_GPL(dax_pgoff_to_phys);
> >
> > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP)
> > +
> > +static void write_dax(void *pmem_addr, struct page *page,
> > + unsigned int off, unsigned int len)
> > +{
> > + unsigned int chunk;
> > + void *mem;
>
> I'd move these two into the loop - similar to what you have
> in other cases with more local scope.
Done, thanks.
>
> > +
> > + while (len) {
> > + mem = kmap_local_page(page);
> > + chunk = min_t(unsigned int, len, PAGE_SIZE - off);
> > + memcpy_flushcache(pmem_addr, mem + off, chunk);
> > + kunmap_local(mem);
> > + len -= chunk;
> > + off = 0;
> > + page++;
> > + pmem_addr += chunk;
> > + }
> > +}
> > +
> > +static long __dev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
> > + long nr_pages, enum dax_access_mode mode, void **kaddr,
> > + pfn_t *pfn)
> > +{
> > + struct dev_dax *dev_dax = dax_get_private(dax_dev);
> > + size_t size = nr_pages << PAGE_SHIFT;
> > + size_t offset = pgoff << PAGE_SHIFT;
> > + void *virt_addr = dev_dax->virt_addr + offset;
> > + u64 flags = PFN_DEV|PFN_MAP;
>
> spaces around the |
>
> Though given it's in just one place, just put these inline next
> to the question...
Done and done.
>
>
> > + phys_addr_t phys;
> > + pfn_t local_pfn;
> > + size_t dax_size;
> > +
> > + WARN_ON(!dev_dax->virt_addr);
> > +
> > + if (down_read_interruptible(&dax_dev_rwsem))
> > + return 0; /* no valid data since we were killed */
> > + dax_size = dev_dax_size(dev_dax);
> > + up_read(&dax_dev_rwsem);
> > +
> > + phys = dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT);
> > +
> > + if (kaddr)
> > + *kaddr = virt_addr;
> > +
> > + local_pfn = phys_to_pfn_t(phys, flags); /* are flags correct? */
> > + if (pfn)
> > + *pfn = local_pfn;
> > +
> > + /* This the valid size at the specified address */
> > + return PHYS_PFN(min_t(size_t, size, dax_size - offset));
> > +}
>
> > +static size_t dev_dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
> > + void *addr, size_t bytes, struct iov_iter *i)
> > +{
> > + size_t off;
> > +
> > + off = offset_in_page(addr);
>
> Unused.
Righto. Thanks.
> > +
> > + return _copy_from_iter_flushcache(addr, bytes, i);
> > +}
>
>
Thanks!
John
