[PATCH v3 0/6] kaddr and pfn can be NULL to ->direct_access()

[PATCH v3 0/6] kaddr and pfn can be NULL to ->direct_access()

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

Changes since v2 [2]:
* Collect Martin and Mike's acks for dcssblk and dm-writecache;
* Rebase the series of patch to v4.18-rc7.

Changes since v1 [1]:
* Involve the previous patches for pfn can be NULL.
* Reword the patch descriptions according to Christian's comment.
* According to Ross's suggestion, replace local pointer dummy_addr
  with NULL within md/dm-writecache for direct_access.

[1]: https://lkml.org/lkml/2018/7/24/199
[2]: https://lkml.org/lkml/2018/7/25/581

Some functions within fs/dax, dax/super and md/dm-writecache don't
need to get local pointer kaddr or variable pfn from direct_access.
Assigning NULL to kaddr or pfn with ->direct_access() is more
straightforward and simple than offering a useless local pointer or
variable.

So all ->direct_access() need to check the validity of pointer kaddr
and pfn for NULL assignment. If either of them is equal to NULL, that
is to say callers may have no need for kaddr or pfn, so this series of
patch are prepared for allowing them to pass in NULL instead of having
to pass in a local pointer or variable that they then just throw away.

Huaisheng Ye (6):
  libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()
  s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
  tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()
  dax/super: Do not request a pointer kaddr when not required
  md/dm-writecache: Don't request pointer dummy_addr when not required
  filesystem-dax: Do not request kaddr and pfn when not required

 drivers/dax/super.c             |  3 +--
 drivers/md/dm-writecache.c      |  3 +--
 drivers/nvdimm/pmem.c           |  7 +++++--
 drivers/s390/block/dcssblk.c    |  8 +++++---
 fs/dax.c                        | 13 ++++---------
 tools/testing/nvdimm/pmem-dax.c | 12 ++++++++----
 6 files changed, 24 insertions(+), 22 deletions(-)

-- 
1.8.3.1

[PATCH v3 1/6] libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

pmem_direct_access() needs to check the validity of pointers kaddr
and pfn for NULL assignment. If anyone equals to NULL, it doesn't need
to calculate the value.

If pointer equals to NULL, that is to say callers may have no need for
kaddr or pfn, so this patch is prepared for allowing them to pass in
NULL instead of having to pass in a pointer or local variable that
they then just throw away.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 drivers/nvdimm/pmem.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 8b1fd7f..ecf9024 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -227,8 +227,11 @@ __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	if (unlikely(is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
 					PFN_PHYS(nr_pages))))
 		return -EIO;
-	*kaddr = pmem->virt_addr + offset;
-	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+
+	if (kaddr)
+		*kaddr = pmem->virt_addr + offset;
+	if (pfn)
+		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
 	/*
 	 * If badblocks are present, limit known good range to the
-- 
1.8.3.1

[PATCH v3 2/6] s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

dcssblk_direct_access() needs to check the validity of pointers kaddr
and pfn for NULL assignment. If anyone equals to NULL, it doesn't need
to calculate the value.

If either of them is equal to NULL, that is to say callers may
have no need for kaddr or pfn, so this patch is prepared for allowing
them to pass in NULL instead of having to pass in a pointer or local
variable that they then just throw away.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 drivers/s390/block/dcssblk.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index ed60728..23e526c 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -922,9 +922,11 @@ static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
 	unsigned long dev_sz;
 
 	dev_sz = dev_info->end - dev_info->start + 1;
-	*kaddr = (void *) dev_info->start + offset;
-	*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
-			PFN_DEV|PFN_SPECIAL);
+	if (kaddr)
+		*kaddr = (void *) dev_info->start + offset;
+	if (pfn)
+		*pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
+				PFN_DEV|PFN_SPECIAL);
 
 	return (dev_sz - offset) / PAGE_SIZE;
 }
-- 
1.8.3.1

[PATCH v3 3/6] tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

The mock / test version of pmem_direct_access() needs to check the
validity of pointers kaddr and pfn for NULL assignment. If anyone
equals to NULL, it doesn't need to calculate the value.

If pointer equals to NULL, that is to say callers may have no need for
kaddr or pfn, so this patch is prepared for allowing them to pass in
NULL instead of having to pass in a local pointer or variable that
they then just throw away.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 tools/testing/nvdimm/pmem-dax.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/tools/testing/nvdimm/pmem-dax.c b/tools/testing/nvdimm/pmem-dax.c
index b53596a..2e7fd82 100644
--- a/tools/testing/nvdimm/pmem-dax.c
+++ b/tools/testing/nvdimm/pmem-dax.c
@@ -31,17 +31,21 @@ long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
 	if (get_nfit_res(pmem->phys_addr + offset)) {
 		struct page *page;
 
-		*kaddr = pmem->virt_addr + offset;
+		if (kaddr)
+			*kaddr = pmem->virt_addr + offset;
 		page = vmalloc_to_page(pmem->virt_addr + offset);
-		*pfn = page_to_pfn_t(page);
+		if (pfn)
+			*pfn = page_to_pfn_t(page);
 		pr_debug_ratelimited("%s: pmem: %p pgoff: %#lx pfn: %#lx\n",
 				__func__, pmem, pgoff, page_to_pfn(page));
 
 		return 1;
 	}
 
-	*kaddr = pmem->virt_addr + offset;
-	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+	if (kaddr)
+		*kaddr = pmem->virt_addr + offset;
+	if (pfn)
+		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
 	/*
 	 * If badblocks are present, limit known good range to the
-- 
1.8.3.1

[PATCH v3 4/6] dax/super: Do not request a pointer kaddr when not required

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

Function __bdev_dax_supported doesn't need to get local pointer kaddr
from direct_access. Using NULL instead of having to pass in a useless
local pointer that caller then just throw away.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 drivers/dax/super.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 45276ab..6e928f3 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -89,7 +89,6 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 	struct request_queue *q;
 	pgoff_t pgoff;
 	int err, id;
-	void *kaddr;
 	pfn_t pfn;
 	long len;
 	char buf[BDEVNAME_SIZE];
@@ -122,7 +121,7 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 	}
 
 	id = dax_read_lock();
-	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
+	len = dax_direct_access(dax_dev, pgoff, 1, NULL, &pfn);
 	dax_read_unlock(id);
 
 	put_dax(dax_dev);
-- 
1.8.3.1

[PATCH v3 5/6] md/dm-writecache: Don't request pointer dummy_addr when not required

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

Function persistent_memory_claim doesn't need to get local pointer
dummy_addr from direct_access. Using NULL instead of having to pass
in a useless local pointer that caller then just throw away.

Suggested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm-writecache.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 87107c9..9d79084 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -268,9 +268,8 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 		i = 0;
 		do {
 			long daa;
-			void *dummy_addr;
 			daa = dax_direct_access(wc->ssd_dev->dax_dev, i, p - i,
-						&dummy_addr, &pfn);
+						NULL, &pfn);
 			if (daa <= 0) {
 				r = daa ? daa : -EINVAL;
 				goto err3;
-- 
1.8.3.1

[PATCH v3 6/6] filesystem-dax: Do not request kaddr and pfn when not required

[Huaisheng Ye]

From: Huaisheng Ye <yehs1@lenovo.com>

Some functions within fs/dax don't need to get local pointer kaddr
or variable pfn from direct_access. Using NULL instead of having to
pass in useless pointer or variable that caller then just throw away.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 6411928..959a533 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -647,7 +647,6 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
 {
 	void *vto, *kaddr;
 	pgoff_t pgoff;
-	pfn_t pfn;
 	long rc;
 	int id;
 
@@ -656,7 +655,7 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
 		return rc;
 
 	id = dax_read_lock();
-	rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
+	rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, NULL);
 	if (rc < 0) {
 		dax_read_unlock(id);
 		return rc;
@@ -967,7 +966,6 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
 {
 	const sector_t sector = dax_iomap_sector(iomap, pos);
 	pgoff_t pgoff;
-	void *kaddr;
 	int id, rc;
 	long length;
 
@@ -976,7 +974,7 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
 		return rc;
 	id = dax_read_lock();
 	length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
-				   &kaddr, pfnp);
+				   NULL, pfnp);
 	if (length < 0) {
 		rc = length;
 		goto out;
@@ -1052,15 +1050,13 @@ int __dax_zero_page_range(struct block_device *bdev,
 		pgoff_t pgoff;
 		long rc, id;
 		void *kaddr;
-		pfn_t pfn;
 
 		rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
 		if (rc)
 			return rc;
 
 		id = dax_read_lock();
-		rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr,
-				&pfn);
+		rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
 		if (rc < 0) {
 			dax_read_unlock(id);
 			return rc;
@@ -1116,7 +1112,6 @@ int __dax_zero_page_range(struct block_device *bdev,
 		ssize_t map_len;
 		pgoff_t pgoff;
 		void *kaddr;
-		pfn_t pfn;
 
 		if (fatal_signal_pending(current)) {
 			ret = -EINTR;
@@ -1128,7 +1123,7 @@ int __dax_zero_page_range(struct block_device *bdev,
 			break;
 
 		map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
-				&kaddr, &pfn);
+				&kaddr, NULL);
 		if (map_len < 0) {
 			ret = map_len;
 			break;
-- 
1.8.3.1

RE: [External] [PATCH v3 0/6] kaddr and pfn can be NULL to ->direct_access()

[Huaisheng HS1 Ye]

Missing one in changes log.

> From: Huaisheng Ye <yehs2007@zoho.com>
> Sent: Monday, July 30, 2018 3:16 PM
> 
> From: Huaisheng Ye <yehs1@lenovo.com>
> 
> Changes since v2 [2]:
> * Collect Martin and Mike's acks for dcssblk and dm-writecache;
> * Rebase the series of patch to v4.18-rc7.
* Collect Ross's reviewed-by for series.

> 
> Changes since v1 [1]:
> * Involve the previous patches for pfn can be NULL.
> * Reword the patch descriptions according to Christian's comment.
> * According to Ross's suggestion, replace local pointer dummy_addr
>   with NULL within md/dm-writecache for direct_access.
> 
> [1]: https://lkml.org/lkml/2018/7/24/199
> [2]: https://lkml.org/lkml/2018/7/25/581
> 
> Some functions within fs/dax, dax/super and md/dm-writecache don't
> need to get local pointer kaddr or variable pfn from direct_access.
> Assigning NULL to kaddr or pfn with ->direct_access() is more
> straightforward and simple than offering a useless local pointer or
> variable.
> 
> So all ->direct_access() need to check the validity of pointer kaddr
> and pfn for NULL assignment. If either of them is equal to NULL, that
> is to say callers may have no need for kaddr or pfn, so this series of
> patch are prepared for allowing them to pass in NULL instead of having
> to pass in a local pointer or variable that they then just throw away.
> 
> Huaisheng Ye (6):
>   libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()
>   s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
>   tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()
>   dax/super: Do not request a pointer kaddr when not required
>   md/dm-writecache: Don't request pointer dummy_addr when not required
>   filesystem-dax: Do not request kaddr and pfn when not required
> 
>  drivers/dax/super.c             |  3 +--
>  drivers/md/dm-writecache.c      |  3 +--
>  drivers/nvdimm/pmem.c           |  7 +++++--
>  drivers/s390/block/dcssblk.c    |  8 +++++---
>  fs/dax.c                        | 13 ++++---------
>  tools/testing/nvdimm/pmem-dax.c | 12 ++++++++----
>  6 files changed, 24 insertions(+), 22 deletions(-)
> 
> --
> 1.8.3.1
> 

Re: [PATCH v3 0/6] kaddr and pfn can be NULL to ->direct_access()

[Dave Jiang]

On 7/30/2018 12:15 AM, Huaisheng Ye wrote:

Applied
> From: Huaisheng Ye <yehs1@lenovo.com>
>
> Changes since v2 [2]:
> * Collect Martin and Mike's acks for dcssblk and dm-writecache;
> * Rebase the series of patch to v4.18-rc7.
>
> Changes since v1 [1]:
> * Involve the previous patches for pfn can be NULL.
> * Reword the patch descriptions according to Christian's comment.
> * According to Ross's suggestion, replace local pointer dummy_addr
>    with NULL within md/dm-writecache for direct_access.
>
> [1]: https://lkml.org/lkml/2018/7/24/199
> [2]: https://lkml.org/lkml/2018/7/25/581
>
> Some functions within fs/dax, dax/super and md/dm-writecache don't
> need to get local pointer kaddr or variable pfn from direct_access.
> Assigning NULL to kaddr or pfn with ->direct_access() is more
> straightforward and simple than offering a useless local pointer or
> variable.
>
> So all ->direct_access() need to check the validity of pointer kaddr
> and pfn for NULL assignment. If either of them is equal to NULL, that
> is to say callers may have no need for kaddr or pfn, so this series of
> patch are prepared for allowing them to pass in NULL instead of having
> to pass in a local pointer or variable that they then just throw away.
>
> Huaisheng Ye (6):
>    libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()
>    s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
>    tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()
>    dax/super: Do not request a pointer kaddr when not required
>    md/dm-writecache: Don't request pointer dummy_addr when not required
>    filesystem-dax: Do not request kaddr and pfn when not required
>
>   drivers/dax/super.c             |  3 +--
>   drivers/md/dm-writecache.c      |  3 +--
>   drivers/nvdimm/pmem.c           |  7 +++++--
>   drivers/s390/block/dcssblk.c    |  8 +++++---
>   fs/dax.c                        | 13 ++++---------
>   tools/testing/nvdimm/pmem-dax.c | 12 ++++++++----
>   6 files changed, 24 insertions(+), 22 deletions(-)
>