diff mbox

[v2,7/7] pmem, dax: have direct_access use __pmem annotation

Message ID 1439484671-15718-8-git-send-email-ross.zwisler@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ross Zwisler Aug. 13, 2015, 4:51 p.m. UTC
Update the annotation for the kaddr pointer returned by direct_access()
so that it is a __pmem pointer.  This is consistent with the PMEM driver
and with how this direct_access() pointer is used in the DAX code.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 Documentation/filesystems/Locking |  3 ++-
 arch/powerpc/sysdev/axonram.c     |  7 ++++---
 drivers/block/brd.c               |  4 ++--
 drivers/nvdimm/pmem.c             |  4 ++--
 drivers/s390/block/dcssblk.c      | 10 +++++----
 fs/block_dev.c                    |  2 +-
 fs/dax.c                          | 44 +++++++++++++++++++++------------------
 include/linux/blkdev.h            |  8 +++----
 8 files changed, 45 insertions(+), 37 deletions(-)

Comments

Dan Williams Aug. 13, 2015, 9:20 p.m. UTC | #1
On Thu, Aug 13, 2015 at 9:51 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> Update the annotation for the kaddr pointer returned by direct_access()
> so that it is a __pmem pointer.  This is consistent with the PMEM driver
> and with how this direct_access() pointer is used in the DAX code.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> ---
>  Documentation/filesystems/Locking |  3 ++-
>  arch/powerpc/sysdev/axonram.c     |  7 ++++---
>  drivers/block/brd.c               |  4 ++--
>  drivers/nvdimm/pmem.c             |  4 ++--
>  drivers/s390/block/dcssblk.c      | 10 +++++----
>  fs/block_dev.c                    |  2 +-
>  fs/dax.c                          | 44 +++++++++++++++++++++------------------
>  include/linux/blkdev.h            |  8 +++----
>  8 files changed, 45 insertions(+), 37 deletions(-)
>
> diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
> index 6a34a0f..06d4434 100644
> --- a/Documentation/filesystems/Locking
> +++ b/Documentation/filesystems/Locking
> @@ -397,7 +397,8 @@ prototypes:
>         int (*release) (struct gendisk *, fmode_t);
>         int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
>         int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
> -       int (*direct_access) (struct block_device *, sector_t, void **, unsigned long *);
> +       int (*direct_access) (struct block_device *, sector_t, void __pmem **,
> +                               unsigned long *);

So this collides with the __pfn_t work.  I think the we have a
reasonable chance of getting that in to 4.3, so I'd wait to see if we
hit any major roadblocks with that set [1] before merging these.

[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-August/001803.html
--
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
Ross Zwisler Aug. 14, 2015, 4:55 p.m. UTC | #2
On Thu, 2015-08-13 at 14:20 -0700, Dan Williams wrote:
> On Thu, Aug 13, 2015 at 9:51 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
> > Update the annotation for the kaddr pointer returned by direct_access()
> > so that it is a __pmem pointer.  This is consistent with the PMEM driver
> > and with how this direct_access() pointer is used in the DAX code.
> >
> > Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> > ---
> >  Documentation/filesystems/Locking |  3 ++-
> >  arch/powerpc/sysdev/axonram.c     |  7 ++++---
> >  drivers/block/brd.c               |  4 ++--
> >  drivers/nvdimm/pmem.c             |  4 ++--
> >  drivers/s390/block/dcssblk.c      | 10 +++++----
> >  fs/block_dev.c                    |  2 +-
> >  fs/dax.c                          | 44 +++++++++++++++++++++------------------
> >  include/linux/blkdev.h            |  8 +++----
> >  8 files changed, 45 insertions(+), 37 deletions(-)
> >
> > diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
> > index 6a34a0f..06d4434 100644
> > --- a/Documentation/filesystems/Locking
> > +++ b/Documentation/filesystems/Locking
> > @@ -397,7 +397,8 @@ prototypes:
> >         int (*release) (struct gendisk *, fmode_t);
> >         int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
> >         int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
> > -       int (*direct_access) (struct block_device *, sector_t, void **, unsigned long *);
> > +       int (*direct_access) (struct block_device *, sector_t, void __pmem **,
> > +                               unsigned long *);
> 
> So this collides with the __pfn_t work.  I think the we have a
> reasonable chance of getting that in to 4.3, so I'd wait to see if we
> hit any major roadblocks with that set [1] before merging these.
> 
> [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-August/001803.html

Fair enough.  Yea, I hadn't merged with that series yet a) because I didn't
know when its review cycle would settle down and b) because that series hadn't
pulled in changes from Matthew for PMD support, which I was originally using
as a baseline.

I'll merge with your code for v3.


--
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
Dan Williams Aug. 14, 2015, 4:58 p.m. UTC | #3
On Fri, Aug 14, 2015 at 9:55 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> On Thu, 2015-08-13 at 14:20 -0700, Dan Williams wrote:
>> On Thu, Aug 13, 2015 at 9:51 AM, Ross Zwisler
>> <ross.zwisler@linux.intel.com> wrote:
>> > Update the annotation for the kaddr pointer returned by direct_access()
>> > so that it is a __pmem pointer.  This is consistent with the PMEM driver
>> > and with how this direct_access() pointer is used in the DAX code.
>> >
>> > Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>> > ---
>> >  Documentation/filesystems/Locking |  3 ++-
>> >  arch/powerpc/sysdev/axonram.c     |  7 ++++---
>> >  drivers/block/brd.c               |  4 ++--
>> >  drivers/nvdimm/pmem.c             |  4 ++--
>> >  drivers/s390/block/dcssblk.c      | 10 +++++----
>> >  fs/block_dev.c                    |  2 +-
>> >  fs/dax.c                          | 44 +++++++++++++++++++++------------------
>> >  include/linux/blkdev.h            |  8 +++----
>> >  8 files changed, 45 insertions(+), 37 deletions(-)
>> >
>> > diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
>> > index 6a34a0f..06d4434 100644
>> > --- a/Documentation/filesystems/Locking
>> > +++ b/Documentation/filesystems/Locking
>> > @@ -397,7 +397,8 @@ prototypes:
>> >         int (*release) (struct gendisk *, fmode_t);
>> >         int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
>> >         int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
>> > -       int (*direct_access) (struct block_device *, sector_t, void **, unsigned long *);
>> > +       int (*direct_access) (struct block_device *, sector_t, void __pmem **,
>> > +                               unsigned long *);
>>
>> So this collides with the __pfn_t work.  I think the we have a
>> reasonable chance of getting that in to 4.3, so I'd wait to see if we
>> hit any major roadblocks with that set [1] before merging these.
>>
>> [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-August/001803.html
>
> Fair enough.  Yea, I hadn't merged with that series yet a) because I didn't
> know when its review cycle would settle down and b) because that series hadn't
> pulled in changes from Matthew for PMD support, which I was originally using
> as a baseline.
>
> I'll merge with your code for v3.

Sounds, let me go rebase the __pfn_t patches on -mm so we'all lined up
and collision free.
--
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
Christoph Hellwig Aug. 15, 2015, 9:11 a.m. UTC | #4
On Fri, Aug 14, 2015 at 09:58:16AM -0700, Dan Williams wrote:
> > I'll merge with your code for v3.
> 
> Sounds, let me go rebase the __pfn_t patches on -mm so we'all lined up
> and collision free.

I'm doubt that we'll have PFN mapping ready for 4.3.  I'd rather see
Ross series goes first, and move the patch to remove the size argument
from ->direct access [1] over to this series as well.

[1] https://git.kernel.org/cgit/linux/kernel/git/djbw/nvdimm.git/commit/?h=pfn&id=8e15e69fb9e61ac563c5a7ffd9dd9a7b545cced3
--
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
Christoph Hellwig Aug. 15, 2015, 9:19 a.m. UTC | #5
On Thu, Aug 13, 2015 at 10:51:11AM -0600, Ross Zwisler wrote:
> Update the annotation for the kaddr pointer returned by direct_access()
> so that it is a __pmem pointer.  This is consistent with the PMEM driver
> and with how this direct_access() pointer is used in the DAX code.

IFF we stick to the __pmem annotations this looks good.

That beeing said I start to really dislike them.  We don't special
accesors to read/write from pmem, we just need to explicitly commit
it if we want to make it persistent.  So I really don't see the need
to treat it special and require all the force casts to and from the
attribute.
--
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
Dan Williams Aug. 15, 2015, 3:44 p.m. UTC | #6
On Sat, Aug 15, 2015 at 2:19 AM, Christoph Hellwig <hch@lst.de> wrote:
> On Thu, Aug 13, 2015 at 10:51:11AM -0600, Ross Zwisler wrote:
>> Update the annotation for the kaddr pointer returned by direct_access()
>> so that it is a __pmem pointer.  This is consistent with the PMEM driver
>> and with how this direct_access() pointer is used in the DAX code.
>
> IFF we stick to the __pmem annotations this looks good.
>
> That beeing said I start to really dislike them.  We don't special
> accesors to read/write from pmem, we just need to explicitly commit
> it if we want to make it persistent.  So I really don't see the need
> to treat it special and require all the force casts to and from the
> attribute.

I'm not going to put up much of a fight if it's really getting in the way....

That said, while we don't need special accessors we do need guarantees
that anything that has written to a persistent memory address has done
so in a way that wmb_pmem() is able to flush it.  It's more of a "I've
audited this code path for wmb_pmem() compatibility so use this api to
write to pmem."

Perhaps a better way to statically check for missed flushes might be
to have acquire_pmem_for_write() + release() annotations and the final
release does a wmb_pmem(), but as far as I can tell the sparse
acquire/release annotations don't stack.
--
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
Dan Williams Aug. 15, 2015, 3:49 p.m. UTC | #7
On Sat, Aug 15, 2015 at 2:11 AM, Christoph Hellwig <hch@lst.de> wrote:
> On Fri, Aug 14, 2015 at 09:58:16AM -0700, Dan Williams wrote:
>> > I'll merge with your code for v3.
>>
>> Sounds, let me go rebase the __pfn_t patches on -mm so we'all lined up
>> and collision free.
>
> I'm doubt that we'll have PFN mapping ready for 4.3.  I'd rather see
> Ross series goes first, and move the patch to remove the size argument
> from ->direct access [1] over to this series as well.
>
> [1] https://git.kernel.org/cgit/linux/kernel/git/djbw/nvdimm.git/commit/?h=pfn&id=8e15e69fb9e61ac563c5a7ffd9dd9a7b545cced3

Yes, let's do it.  The need for DAX persistence guarantees is a higher
priority than solving the DAX vs PMEM unbind bug.  Especially if we
can defer __pfn_t and get some basic struct page mapping into 4.3 as
well.
--
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
Christoph Hellwig Aug. 15, 2015, 4 p.m. UTC | #8
On Sat, Aug 15, 2015 at 08:44:27AM -0700, Dan Williams wrote:
> That said, while we don't need special accessors we do need guarantees
> that anything that has written to a persistent memory address has done
> so in a way that wmb_pmem() is able to flush it.  It's more of a "I've
> audited this code path for wmb_pmem() compatibility so use this api to
> write to pmem."

I'm more worried about things where don't just do plain loads and stores
to a pmem region but DMA, which will end up as a nightmare of casts.

But we can wait and see how that evolves in the end..
--
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
Dan Williams Aug. 15, 2015, 6:05 p.m. UTC | #9
On Sat, Aug 15, 2015 at 9:00 AM, Christoph Hellwig <hch@lst.de> wrote:
> On Sat, Aug 15, 2015 at 08:44:27AM -0700, Dan Williams wrote:
>> That said, while we don't need special accessors we do need guarantees
>> that anything that has written to a persistent memory address has done
>> so in a way that wmb_pmem() is able to flush it.  It's more of a "I've
>> audited this code path for wmb_pmem() compatibility so use this api to
>> write to pmem."
>
> I'm more worried about things where don't just do plain loads and stores
> to a pmem region but DMA, which will end up as a nightmare of casts.
>
> But we can wait and see how that evolves in the end..

It's already not possible to do something like dma_map_single() on an
ioremap()'d address, so there currently are't any __iomem/DMA
collisions.  As long as DMA setup is relative to a physical address
resource I think we're ok.

Making sure a DMA is both complete and persistent though is a different problem.
--
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
Ross Zwisler Aug. 17, 2015, 8:07 p.m. UTC | #10
On Sat, 2015-08-15 at 08:44 -0700, Dan Williams wrote:
> On Sat, Aug 15, 2015 at 2:19 AM, Christoph Hellwig <hch@lst.de> wrote:
> > On Thu, Aug 13, 2015 at 10:51:11AM -0600, Ross Zwisler wrote:
> >> Update the annotation for the kaddr pointer returned by direct_access()
> >> so that it is a __pmem pointer.  This is consistent with the PMEM driver
> >> and with how this direct_access() pointer is used in the DAX code.
> >
> > IFF we stick to the __pmem annotations this looks good.
> >
> > That beeing said I start to really dislike them.  We don't special
> > accesors to read/write from pmem, we just need to explicitly commit
> > it if we want to make it persistent.  So I really don't see the need
> > to treat it special and require all the force casts to and from the
> > attribute.
> 
> I'm not going to put up much of a fight if it's really getting in the way....
> 
> That said, while we don't need special accessors we do need guarantees
> that anything that has written to a persistent memory address has done
> so in a way that wmb_pmem() is able to flush it.  It's more of a "I've
> audited this code path for wmb_pmem() compatibility so use this api to
> write to pmem."
> 
> Perhaps a better way to statically check for missed flushes might be
> to have acquire_pmem_for_write() + release() annotations and the final
> release does a wmb_pmem(), but as far as I can tell the sparse
> acquire/release annotations don't stack.

FWIW I've been on the fence about the __pmem annotations, but my current
thought is that we really do need a way of saying that stores to these
pointers need special care for wmb_pmem() to do its thing and that __pmem does
a reasonably good job of that.  If we can figure out a cooler way, such as the
write() + release() flow Dan is talking about, great.  But I think we need
something to keep us from making errors by storing to PMEM pointers and
leaving data in the processor cache.


--
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 mbox

Patch

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 6a34a0f..06d4434 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -397,7 +397,8 @@  prototypes:
 	int (*release) (struct gendisk *, fmode_t);
 	int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
-	int (*direct_access) (struct block_device *, sector_t, void **, unsigned long *);
+	int (*direct_access) (struct block_device *, sector_t, void __pmem **,
+				unsigned long *);
 	int (*media_changed) (struct gendisk *);
 	void (*unlock_native_capacity) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);
diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index ee90db1..a2be2a6 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -141,13 +141,14 @@  axon_ram_make_request(struct request_queue *queue, struct bio *bio)
  */
 static long
 axon_ram_direct_access(struct block_device *device, sector_t sector,
-		       void **kaddr, unsigned long *pfn, long size)
+		       void __pmem **kaddr, unsigned long *pfn, long size)
 {
 	struct axon_ram_bank *bank = device->bd_disk->private_data;
 	loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
+	void *addr = (void *)(bank->ph_addr + offset);
 
-	*kaddr = (void *)(bank->ph_addr + offset);
-	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
+	*kaddr = (void __pmem *)addr;
+	*pfn = virt_to_phys(addr) >> PAGE_SHIFT;
 
 	return bank->size - offset;
 }
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 5750b39..2691bb6 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -371,7 +371,7 @@  static int brd_rw_page(struct block_device *bdev, sector_t sector,
 
 #ifdef CONFIG_BLK_DEV_RAM_DAX
 static long brd_direct_access(struct block_device *bdev, sector_t sector,
-			void **kaddr, unsigned long *pfn, long size)
+			void __pmem **kaddr, unsigned long *pfn, long size)
 {
 	struct brd_device *brd = bdev->bd_disk->private_data;
 	struct page *page;
@@ -381,7 +381,7 @@  static long brd_direct_access(struct block_device *bdev, sector_t sector,
 	page = brd_insert_page(brd, sector);
 	if (!page)
 		return -ENOSPC;
-	*kaddr = page_address(page);
+	*kaddr = (void __pmem *)page_address(page);
 	*pfn = page_to_pfn(page);
 
 	/*
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index ade9eb9..68f6a6a 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -92,7 +92,7 @@  static int pmem_rw_page(struct block_device *bdev, sector_t sector,
 }
 
 static long pmem_direct_access(struct block_device *bdev, sector_t sector,
-			      void **kaddr, unsigned long *pfn, long size)
+		      void __pmem **kaddr, unsigned long *pfn, long size)
 {
 	struct pmem_device *pmem = bdev->bd_disk->private_data;
 	size_t offset = sector << 9;
@@ -101,7 +101,7 @@  static long pmem_direct_access(struct block_device *bdev, sector_t sector,
 		return -ENODEV;
 
 	/* FIXME convert DAX to comprehend that this mapping has a lifetime */
-	*kaddr = (void __force *) pmem->virt_addr + offset;
+	*kaddr = pmem->virt_addr + offset;
 	*pfn = (pmem->phys_addr + offset) >> PAGE_SHIFT;
 
 	return pmem->size - offset;
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index da21281..2c5a397 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -29,7 +29,7 @@  static int dcssblk_open(struct block_device *bdev, fmode_t mode);
 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
 static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
 static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
-				 void **kaddr, unsigned long *pfn, long size);
+			 void __pmem **kaddr, unsigned long *pfn, long size);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -879,18 +879,20 @@  fail:
 
 static long
 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
-			void **kaddr, unsigned long *pfn, long size)
+			void __pmem **kaddr, unsigned long *pfn, long size)
 {
 	struct dcssblk_dev_info *dev_info;
 	unsigned long offset, dev_sz;
+	void *addr;
 
 	dev_info = bdev->bd_disk->private_data;
 	if (!dev_info)
 		return -ENODEV;
 	dev_sz = dev_info->end - dev_info->start;
 	offset = secnum * 512;
-	*kaddr = (void *) (dev_info->start + offset);
-	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
+	addr = (void *) (dev_info->start + offset);
+	*pfn = virt_to_phys(addr) >> PAGE_SHIFT;
+	*kaddr = (void __pmem *) addr;
 
 	return dev_sz - offset;
 }
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9be2d7e..4ab366d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -442,7 +442,7 @@  EXPORT_SYMBOL_GPL(bdev_write_page);
  * accessible at this address.
  */
 long bdev_direct_access(struct block_device *bdev, sector_t sector,
-			void **addr, unsigned long *pfn, long size)
+			void __pmem **addr, unsigned long *pfn, long size)
 {
 	long avail;
 	const struct block_device_operations *ops = bdev->bd_disk->fops;
diff --git a/fs/dax.c b/fs/dax.c
index ea1b2c8..633a1ba 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -36,7 +36,7 @@  int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 
 	might_sleep();
 	do {
-		void *addr;
+		void __pmem *addr;
 		unsigned long pfn;
 		long count;
 
@@ -48,7 +48,7 @@  int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 			unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
 			if (pgsz > count)
 				pgsz = count;
-			clear_pmem((void __pmem *)addr, pgsz);
+			clear_pmem(addr, pgsz);
 			addr += pgsz;
 			size -= pgsz;
 			count -= pgsz;
@@ -63,7 +63,8 @@  int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 }
 EXPORT_SYMBOL_GPL(dax_clear_blocks);
 
-static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits)
+static long dax_get_addr(struct buffer_head *bh, void __pmem **addr,
+		unsigned blkbits)
 {
 	unsigned long pfn;
 	sector_t sector = bh->b_blocknr << (blkbits - 9);
@@ -71,15 +72,15 @@  static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits)
 }
 
 /* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
-static void dax_new_buf(void *addr, unsigned size, unsigned first, loff_t pos,
-			loff_t end)
+static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
+		loff_t pos, loff_t end)
 {
 	loff_t final = end - pos + first; /* The final byte of the buffer */
 
 	if (first > 0)
-		clear_pmem((void __pmem *)addr, first);
+		clear_pmem(addr, first);
 	if (final < size)
-		clear_pmem((void __pmem *)addr + final, size - final);
+		clear_pmem(addr + final, size - final);
 }
 
 static bool buffer_written(struct buffer_head *bh)
@@ -107,7 +108,7 @@  static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 	loff_t pos = start;
 	loff_t max = start;
 	loff_t bh_max = start;
-	void *addr;
+	void __pmem *addr;
 	bool hole = false;
 	bool need_wmb = false;
 
@@ -159,16 +160,18 @@  static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 		}
 
 		if (iov_iter_rw(iter) == WRITE) {
-			len = copy_from_iter_nocache(addr, max - pos, iter);
+			len = copy_from_iter_nocache((void __force *)addr,
+					max - pos, iter);
 			/*
 			 * copy_from_iter_nocache() uses non-temporal stores
 			 * for iovec iterators so we can skip the write back.
 			 */
 			if (!iter_is_iovec(iter))
-				wb_cache_pmem((void __pmem *)addr, max - pos);
+				wb_cache_pmem(addr, max - pos);
 			need_wmb = true;
 		} else if (!hole)
-			len = copy_to_iter(addr, max - pos, iter);
+			len = copy_to_iter((void __force *)addr, max - pos,
+					iter);
 		else
 			len = iov_iter_zero(max - pos, iter);
 
@@ -274,11 +277,13 @@  static int dax_load_hole(struct address_space *mapping, struct page *page,
 static int copy_user_bh(struct page *to, struct buffer_head *bh,
 			unsigned blkbits, unsigned long vaddr)
 {
-	void *vfrom, *vto;
+	void __pmem *vfrom;
+	void *vto;
+
 	if (dax_get_addr(bh, &vfrom, blkbits) < 0)
 		return -EIO;
 	vto = kmap_atomic(to);
-	copy_user_page(vto, vfrom, vaddr, to);
+	copy_user_page(vto, (void __force *)vfrom, vaddr, to);
 	kunmap_atomic(vto);
 	return 0;
 }
@@ -288,7 +293,7 @@  static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 {
 	sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
 	unsigned long vaddr = (unsigned long)vmf->virtual_address;
-	void *addr;
+	void __pmem *addr;
 	unsigned long pfn;
 	pgoff_t size;
 	int error;
@@ -315,7 +320,7 @@  static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 	}
 
 	if (buffer_unwritten(bh) || buffer_new(bh)) {
-		clear_pmem((void __pmem *)addr, PAGE_SIZE);
+		clear_pmem(addr, PAGE_SIZE);
 		wmb_pmem();
 	}
 
@@ -530,7 +535,7 @@  int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	unsigned long pmd_addr = address & PMD_MASK;
 	bool write = flags & FAULT_FLAG_WRITE;
 	long length;
-	void *kaddr;
+	void __pmem *kaddr;
 	pgoff_t size, pgoff;
 	sector_t block, sector;
 	unsigned long pfn;
@@ -624,8 +629,7 @@  int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		if (buffer_unwritten(&bh) || buffer_new(&bh)) {
 			int i;
 			for (i = 0; i < PTRS_PER_PMD; i++)
-				clear_pmem((void __pmem *)kaddr + i*PAGE_SIZE,
-						PAGE_SIZE);
+				clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
 			wmb_pmem();
 			count_vm_event(PGMAJFAULT);
 			mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
@@ -734,11 +738,11 @@  int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
 	if (err < 0)
 		return err;
 	if (buffer_written(&bh)) {
-		void *addr;
+		void __pmem *addr;
 		err = dax_get_addr(&bh, &addr, inode->i_blkbits);
 		if (err < 0)
 			return err;
-		clear_pmem((void __pmem *)addr + offset, length);
+		clear_pmem(addr + offset, length);
 		wmb_pmem();
 	}
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d4068c1..c401ecd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1555,8 +1555,8 @@  struct block_device_operations {
 	int (*rw_page)(struct block_device *, sector_t, struct page *, int rw);
 	int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
-	long (*direct_access)(struct block_device *, sector_t,
-					void **, unsigned long *pfn, long size);
+	long (*direct_access)(struct block_device *, sector_t, void __pmem **,
+			unsigned long *pfn, long size);
 	unsigned int (*check_events) (struct gendisk *disk,
 				      unsigned int clearing);
 	/* ->media_changed() is DEPRECATED, use ->check_events() instead */
@@ -1574,8 +1574,8 @@  extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
 extern int bdev_read_page(struct block_device *, sector_t, struct page *);
 extern int bdev_write_page(struct block_device *, sector_t, struct page *,
 						struct writeback_control *);
-extern long bdev_direct_access(struct block_device *, sector_t, void **addr,
-						unsigned long *pfn, long size);
+extern long bdev_direct_access(struct block_device *, sector_t,
+		void __pmem **addr, unsigned long *pfn, long size);
 #else /* CONFIG_BLOCK */
 
 struct block_device;