[RFC PATCH 0/6] dax: Replace bdev_dax_pgoff() with dax_pgoff()

[RFC PATCH 0/6] dax: Replace bdev_dax_pgoff() with dax_pgoff()

[Vivek Goyal]

Currently dax code assumes that there is always a block device
associated with it. And block device is passed around in few routines. I
am implementing DAX support for virtiofs and there is no block device
while we are using dax device. So I need dax code to move away from
this assumption that there is always a block device.

We seem to pass around block deivce only to calculate the partition
offset into dax device. bdev_dax_pgoff() does get_start_sect(bdev).

There are two proposed solutions to this problem.

- Get rid of kernel partition support for pmem devices.

- Caller stores offset into dax device and passes that in along with
  dax_device.

First solution was discussed recently in this thread.

https://lore.kernel.org/linux-fsdevel/20200107125159.GA15745@infradead.org/

I feel we already shipped partition support for dax block devices and
going back now will be painful and its easy to break users out there
which are using partitions.

Hence I thought of writing patches for second proposal and see how bad
it looks. To me patches are fairly small and don't break backward 
compatibility and seem like a good step in the direction of removing
dax assumptions about block device.

So I am posting this RFC patch series, which is just boot tested.

Any feedback or comments are welcome.

Thanks
Vivek
 

Vivek Goyal (6):
  dax: Define a helper dax_pgoff() which takes in dax_offset as argument
  dax,iomap,ext4,ext2,xfs: Save dax_offset in "struct iomap"
  fs/dax.c: Start using dax_pgoff() instead of bdev_dax_pgoff()
  dax, dm/md: Use dax_pgoff() instead of bdev_dax_pgoff()
  drivers/dax: Use dax_pgoff() instead of bdev_dax_pgoff()
  dax: Remove bdev_dax_pgoff() helper

 drivers/dax/super.c        | 11 +++++------
 drivers/md/dm-linear.c     |  9 ++++++---
 drivers/md/dm-log-writes.c |  9 ++++++---
 drivers/md/dm-stripe.c     |  8 +++++---
 fs/dax.c                   | 13 ++++++-------
 fs/ext2/inode.c            |  1 +
 fs/ext4/inode.c            |  1 +
 fs/xfs/xfs_iomap.c         |  2 ++
 include/linux/dax.h        |  2 +-
 include/linux/iomap.h      |  1 +
 10 files changed, 34 insertions(+), 23 deletions(-)

-- 
2.20.1

[PATCH 1/6] dax: Define a helper dax_pgoff() which takes in dax_offset as argument

[Vivek Goyal]

Create a new helper dax_pgoff() which will replace bdev_dax_pgoff(). Difference
between two is that dax_pgoff() takes in "sector_t dax_offset" as an argument
instead of "struct block_device".

dax_offset specifies any offset into dax device which should be added to
sector while calculating pgoff.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 drivers/dax/super.c | 12 ++++++++++++
 include/linux/dax.h |  1 +
 2 files changed, 13 insertions(+)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 0aa4b6bc5101..e9daa30e4250 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -56,6 +56,18 @@ int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
 }
 EXPORT_SYMBOL(bdev_dax_pgoff);
 
+int dax_pgoff(sector_t dax_offset, sector_t sector, size_t size, pgoff_t *pgoff)
+{
+	phys_addr_t phys_off = (dax_offset + sector) * 512;
+
+	if (pgoff)
+		*pgoff = PHYS_PFN(phys_off);
+	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
+		return -EINVAL;
+	return 0;
+}
+EXPORT_SYMBOL(dax_pgoff);
+
 #if IS_ENABLED(CONFIG_FS_DAX)
 struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 {
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 328c2dbb4409..5101a4b5c1f9 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -111,6 +111,7 @@ static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
 
 struct writeback_control;
 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
+int dax_pgoff(sector_t dax_offset, sector_t, size_t, pgoff_t *pgoff);
 #if IS_ENABLED(CONFIG_FS_DAX)
 bool __bdev_dax_supported(struct block_device *bdev, int blocksize);
 static inline bool bdev_dax_supported(struct block_device *bdev, int blocksize)
-- 
2.20.1

Re: [PATCH 1/6] dax: Define a helper dax_pgoff() which takes in dax_offset as argument

[Christoph Hellwig]

On Wed, Feb 12, 2020 at 12:07:28PM -0500, Vivek Goyal wrote:
> Create a new helper dax_pgoff() which will replace bdev_dax_pgoff(). Difference
> between two is that dax_pgoff() takes in "sector_t dax_offset" as an argument
> instead of "struct block_device".
> 
> dax_offset specifies any offset into dax device which should be added to
> sector while calculating pgoff.
> 
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
>  drivers/dax/super.c | 12 ++++++++++++
>  include/linux/dax.h |  1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 0aa4b6bc5101..e9daa30e4250 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -56,6 +56,18 @@ int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
>  }
>  EXPORT_SYMBOL(bdev_dax_pgoff);
>  
> +int dax_pgoff(sector_t dax_offset, sector_t sector, size_t size, pgoff_t *pgoff)

Please add a kerneldoc document.  I can't really make sense of what
dax_offset and sector mean here and why they are passed separately.

> +{
> +	phys_addr_t phys_off = (dax_offset + sector) * 512;

							<< SECTOR_SHIFT;

> +
> +	if (pgoff)
> +		*pgoff = PHYS_PFN(phys_off);

What is the use case of not passing a pgoff argument?

> +	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
> +		return -EINVAL;
> +	return 0;
> +}
> +EXPORT_SYMBOL(dax_pgoff);

EXPORT_SYMBOL_GPL, please.

Re: [PATCH 1/6] dax: Define a helper dax_pgoff() which takes in dax_offset as argument

[Matthew Wilcox]

On Wed, Feb 12, 2020 at 12:07:28PM -0500, Vivek Goyal wrote:
> +int dax_pgoff(sector_t dax_offset, sector_t sector, size_t size, pgoff_t *pgoff)
> +{
> +	phys_addr_t phys_off = (dax_offset + sector) * 512;
> +
> +	if (pgoff)
> +		*pgoff = PHYS_PFN(phys_off);
> +	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
> +		return -EINVAL;
> +	return 0;

This is why we have IS_ERR_VALUE().  Just make this function return
a pgoff_t.

[PATCH 2/6] dax,iomap,ext4,ext2,xfs: Save dax_offset in "struct iomap"

[Vivek Goyal]

Add a new field "sector_t dax_offset" to "struct iomap". This will be
filled by filesystems and dax code will make use of this to convert
sector into page offset (dax_pgoff()), instead of bdev_dax_pgoff(). This
removes the dependency of having to pass in block device for dax operations.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 fs/ext2/inode.c       | 1 +
 fs/ext4/inode.c       | 1 +
 fs/xfs/xfs_iomap.c    | 2 ++
 include/linux/iomap.h | 1 +
 4 files changed, 5 insertions(+)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index c885cf7d724b..5c3379e78d49 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -823,6 +823,7 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	iomap->bdev = inode->i_sb->s_bdev;
 	iomap->offset = (u64)first_block << blkbits;
 	iomap->dax_dev = sbi->s_daxdev;
+	iomap->dax_offset = get_start_sect(iomap->bdev);
 
 	if (ret == 0) {
 		iomap->type = IOMAP_HOLE;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1305b810c44a..0ea7fbb8076f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3330,6 +3330,7 @@ static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
 
 	iomap->bdev = inode->i_sb->s_bdev;
 	iomap->dax_dev = EXT4_SB(inode->i_sb)->s_daxdev;
+	iomap->dax_offset = get_start_sect(iomap->bdev);
 	iomap->offset = (u64) map->m_lblk << blkbits;
 	iomap->length = (u64) map->m_len << blkbits;
 
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index bb590a267a7f..ad8b18fc96fd 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -80,6 +80,7 @@ xfs_bmbt_to_iomap(
 	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
 	iomap->bdev = target->bt_bdev;
 	iomap->dax_dev = target->bt_daxdev;
+	iomap->dax_offset = get_start_sect(iomap->bdev);
 	iomap->flags = flags;
 
 	if (xfs_ipincount(ip) &&
@@ -103,6 +104,7 @@ xfs_hole_to_iomap(
 	iomap->length = XFS_FSB_TO_B(ip->i_mount, end_fsb - offset_fsb);
 	iomap->bdev = target->bt_bdev;
 	iomap->dax_dev = target->bt_daxdev;
+	iomap->dax_offset = get_start_sect(iomap->bdev);
 }
 
 static inline xfs_fileoff_t
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 8b09463dae0d..cac5d667aa74 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -84,6 +84,7 @@ struct iomap {
 	u16			flags;	/* flags for mapping */
 	struct block_device	*bdev;	/* block device for I/O */
 	struct dax_device	*dax_dev; /* dax_dev for dax operations */
+	sector_t		dax_offset; /* offset in dax device */
 	void			*inline_data;
 	void			*private; /* filesystem private */
 	const struct iomap_page_ops *page_ops;
-- 
2.20.1

Re: [PATCH 2/6] dax,iomap,ext4,ext2,xfs: Save dax_offset in "struct iomap"

[Christoph Hellwig]

On Wed, Feb 12, 2020 at 12:07:29PM -0500, Vivek Goyal wrote:
> Add a new field "sector_t dax_offset" to "struct iomap". This will be
> filled by filesystems and dax code will make use of this to convert
> sector into page offset (dax_pgoff()), instead of bdev_dax_pgoff(). This
> removes the dependency of having to pass in block device for dax operations.

NAK.  The iomap is not a structure to bolt random layering violation
onto.

[PATCH 3/6] fs/dax.c: Start using dax_pgoff() instead of bdev_dax_pgoff()

[Vivek Goyal]

Replace usage of bdev_dax_pgoff() with dax_pgoff() in fs/dax.c

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 fs/dax.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 35da144375a0..921042a81538 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -680,7 +680,7 @@ int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 	return __dax_invalidate_entry(mapping, index, false);
 }
 
-static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
+static int copy_user_dax(struct dax_device *dax_dev, sector_t dax_offset,
 		sector_t sector, size_t size, struct page *to,
 		unsigned long vaddr)
 {
@@ -689,7 +689,7 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
 	long rc;
 	int id;
 
-	rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+	rc = dax_pgoff(dax_offset, sector, size, &pgoff);
 	if (rc)
 		return rc;
 
@@ -990,7 +990,7 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
 	int id, rc;
 	long length;
 
-	rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff);
+	rc = dax_pgoff(iomap->dax_offset, sector, size, &pgoff);
 	if (rc)
 		return rc;
 	id = dax_read_lock();
@@ -1065,7 +1065,7 @@ int __dax_zero_page_range(struct block_device *bdev,
 		long rc, id;
 		void *kaddr;
 
-		rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
+		rc = dax_pgoff(get_start_sect(bdev), sector, PAGE_SIZE, &pgoff);
 		if (rc)
 			return rc;
 
@@ -1087,7 +1087,6 @@ static loff_t
 dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		struct iomap *iomap, struct iomap *srcmap)
 {
-	struct block_device *bdev = iomap->bdev;
 	struct dax_device *dax_dev = iomap->dax_dev;
 	struct iov_iter *iter = data;
 	loff_t end = pos + length, done = 0;
@@ -1132,7 +1131,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 			break;
 		}
 
-		ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+		ret = dax_pgoff(iomap->dax_offset, sector, size, &pgoff);
 		if (ret)
 			break;
 
@@ -1312,7 +1311,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 			clear_user_highpage(vmf->cow_page, vaddr);
 			break;
 		case IOMAP_MAPPED:
-			error = copy_user_dax(iomap.bdev, iomap.dax_dev,
+			error = copy_user_dax(iomap.dax_dev, iomap.dax_offset,
 					sector, PAGE_SIZE, vmf->cow_page, vaddr);
 			break;
 		default:
-- 
2.20.1

[PATCH 4/6] dax, dm/md: Use dax_pgoff() instead of bdev_dax_pgoff()

[Vivek Goyal]

Replace usage of bdev_dax_pgoff() with dax_pgoff().

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 drivers/md/dm-linear.c     | 9 ++++++---
 drivers/md/dm-log-writes.c | 9 ++++++---
 drivers/md/dm-stripe.c     | 8 +++++---
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 8d07fdf63a47..05f654044185 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -167,7 +167,8 @@ static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 
 	dev_sector = linear_map_sector(ti, sector);
-	ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
+	ret = dax_pgoff(get_start_sect(bdev), dev_sector, nr_pages * PAGE_SIZE,
+			&pgoff);
 	if (ret)
 		return ret;
 	return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
@@ -182,7 +183,8 @@ static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
 	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 
 	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+	if (dax_pgoff(get_start_sect(bdev), dev_sector, ALIGN(bytes, PAGE_SIZE),
+		      &pgoff))
 		return 0;
 	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 }
@@ -196,7 +198,8 @@ static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
 	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
 
 	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+	if (dax_pgoff(get_start_sect(bdev), dev_sector, ALIGN(bytes, PAGE_SIZE),
+		      &pgoff))
 		return 0;
 	return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
 }
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 99721c76225d..204fbceeb97e 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -952,7 +952,8 @@ static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 	sector_t sector = pgoff * PAGE_SECTORS;
 	int ret;
 
-	ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages * PAGE_SIZE, &pgoff);
+	ret = dax_pgoff(get_start_sect(lc->dev->bdev), sector,
+			nr_pages * PAGE_SIZE, &pgoff);
 	if (ret)
 		return ret;
 	return dax_direct_access(lc->dev->dax_dev, pgoff, nr_pages, kaddr, pfn);
@@ -966,7 +967,8 @@ static size_t log_writes_dax_copy_from_iter(struct dm_target *ti,
 	sector_t sector = pgoff * PAGE_SECTORS;
 	int err;
 
-	if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+	if (dax_pgoff(get_start_sect(lc->dev->bdev), sector,
+		      ALIGN(bytes, PAGE_SIZE), &pgoff))
 		return 0;
 
 	/* Don't bother doing anything if logging has been disabled */
@@ -989,7 +991,8 @@ static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
 	struct log_writes_c *lc = ti->private;
 	sector_t sector = pgoff * PAGE_SECTORS;
 
-	if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+	if (dax_pgoff(get_start_sect(lc->dev->bdev), sector,
+		      ALIGN(bytes, PAGE_SIZE), &pgoff))
 		return 0;
 	return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
 }
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 63bbcc20f49a..337cdc6e0951 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -316,7 +316,8 @@ static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 	dax_dev = sc->stripe[stripe].dev->dax_dev;
 	bdev = sc->stripe[stripe].dev->bdev;
 
-	ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
+	ret = dax_pgoff(get_start_sect(bdev), dev_sector, nr_pages * PAGE_SIZE,
+			&pgoff);
 	if (ret)
 		return ret;
 	return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
@@ -336,7 +337,7 @@ static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
 	dax_dev = sc->stripe[stripe].dev->dax_dev;
 	bdev = sc->stripe[stripe].dev->bdev;
 
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+	if (dax_pgoff(get_start_sect(bdev), dev_sector, ALIGN(bytes, PAGE_SIZE),		      &pgoff))
 		return 0;
 	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 }
@@ -355,7 +356,8 @@ static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
 	dax_dev = sc->stripe[stripe].dev->dax_dev;
 	bdev = sc->stripe[stripe].dev->bdev;
 
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+	if (dax_pgoff(get_start_sect(bdev), dev_sector, ALIGN(bytes, PAGE_SIZE),
+		      &pgoff))
 		return 0;
 	return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
 }
-- 
2.20.1

[PATCH 5/6] drivers/dax: Use dax_pgoff() instead of bdev_dax_pgoff()

[Vivek Goyal]

Start using dax_pgoff() instead of bdev_dax_pgoff().

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 drivers/dax/super.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e9daa30e4250..ee35ecc61545 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -97,7 +97,7 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 		return false;
 	}
 
-	err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff);
+	err = dax_pgoff(get_start_sect(bdev), start, PAGE_SIZE, &pgoff);
 	if (err) {
 		pr_debug("%s: error: unaligned partition for dax\n",
 				bdevname(bdev, buf));
@@ -105,7 +105,7 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 	}
 
 	last_page = PFN_DOWN((start + sectors - 1) * 512) * PAGE_SIZE / 512;
-	err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
+	err = dax_pgoff(get_start_sect(bdev), last_page, PAGE_SIZE, &pgoff_end);
 	if (err) {
 		pr_debug("%s: error: unaligned partition for dax\n",
 				bdevname(bdev, buf));
-- 
2.20.1

[PATCH 6/6] dax: Remove bdev_dax_pgoff() helper

[Vivek Goyal]

Now there don't seem to be anyuser of bdev_dax_pgoff(). All users have been
moved to dax_pgoff(). So remove this helper.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 drivers/dax/super.c | 13 -------------
 include/linux/dax.h |  1 -
 2 files changed, 14 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index ee35ecc61545..371e391e6b1e 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -43,19 +43,6 @@ EXPORT_SYMBOL_GPL(dax_read_unlock);
 #ifdef CONFIG_BLOCK
 #include <linux/blkdev.h>
 
-int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
-		pgoff_t *pgoff)
-{
-	phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512;
-
-	if (pgoff)
-		*pgoff = PHYS_PFN(phys_off);
-	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
-		return -EINVAL;
-	return 0;
-}
-EXPORT_SYMBOL(bdev_dax_pgoff);
-
 int dax_pgoff(sector_t dax_offset, sector_t sector, size_t size, pgoff_t *pgoff)
 {
 	phys_addr_t phys_off = (dax_offset + sector) * 512;
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 5101a4b5c1f9..84ed0e993190 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -110,7 +110,6 @@ static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
 #endif
 
 struct writeback_control;
-int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
 int dax_pgoff(sector_t dax_offset, sector_t, size_t, pgoff_t *pgoff);
 #if IS_ENABLED(CONFIG_FS_DAX)
 bool __bdev_dax_supported(struct block_device *bdev, int blocksize);
-- 
2.20.1