diff mbox series

[3/7] dax: Check the end of the block-device capacity with dax_direct_access()

Message ID 155000669646.348031.16690970886357498896.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive)
State New, archived
Headers show
Series libnvdimm/pfn: Fix section-alignment padding | expand

Commit Message

Dan Williams Feb. 12, 2019, 9:24 p.m. UTC 
The checks in __bdev_dax_supported() helped mitigate a potential data
corruption bug in the pmem driver's handling of section alignment
padding. Strengthen the checks, including checking the end of the range,
to validate the dev_pagemap, Xarray entries, and sector-to-pfn
translation established for pmem namespaces.

Cc: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/dax/super.c |   39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

Comments

Jan Kara Feb. 13, 2019, 10:22 a.m. UTC | #1 
On Tue 12-02-19 13:24:56, Dan Williams wrote:
> The checks in __bdev_dax_supported() helped mitigate a potential data
> corruption bug in the pmem driver's handling of section alignment
> padding. Strengthen the checks, including checking the end of the range,
> to validate the dev_pagemap, Xarray entries, and sector-to-pfn
> translation established for pmem namespaces.
> 
> Cc: Jan Kara <jack@suse.cz>
> Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/dax/super.c |   39 +++++++++++++++++++++++++++++----------
>  1 file changed, 29 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 6e928f37d084..a27395cfcec6 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -86,12 +86,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
>  {
>  	struct dax_device *dax_dev;
>  	bool dax_enabled = false;
> +	pgoff_t pgoff, pgoff_end;
>  	struct request_queue *q;
> -	pgoff_t pgoff;
> -	int err, id;
> -	pfn_t pfn;
> -	long len;
>  	char buf[BDEVNAME_SIZE];
> +	void *kaddr, *end_kaddr;
> +	pfn_t pfn, end_pfn;
> +	sector_t last_page;
> +	long len, len2;
> +	int err, id;
>  
>  	if (blocksize != PAGE_SIZE) {
>  		pr_debug("%s: error: unsupported blocksize for dax\n",
> @@ -113,6 +115,15 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
>  		return false;
>  	}
>  
> +	last_page = ALIGN_DOWN(part_nr_sects_read(bdev->bd_part)
> +			- PAGE_SIZE / 512, PAGE_SIZE / 512);

Why not just (i_size_read(bdev->bd_inode) - 1) >> PAGE_SHIFT? Otherwise the
patch looks good to me.

								Honza


> +	err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
> +	if (err) {
> +		pr_debug("%s: error: unaligned partition for dax\n",
> +				bdevname(bdev, buf));
> +		return false;
> +	}
> +
>  	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
>  	if (!dax_dev) {
>  		pr_debug("%s: error: device does not support dax\n",
> @@ -121,14 +132,15 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
>  	}
>  
>  	id = dax_read_lock();
> -	len = dax_direct_access(dax_dev, pgoff, 1, NULL, &pfn);
> +	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
> +	len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
>  	dax_read_unlock(id);
>  
>  	put_dax(dax_dev);
>  
> -	if (len < 1) {
> +	if (len < 1 || len2 < 1) {
>  		pr_debug("%s: error: dax access failed (%ld)\n",
> -				bdevname(bdev, buf), len);
> +				bdevname(bdev, buf), len < 1 ? len : len2);
>  		return false;
>  	}
>  
> @@ -143,13 +155,20 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
>  		 */
>  		WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
>  		dax_enabled = true;
> -	} else if (pfn_t_devmap(pfn)) {
> -		struct dev_pagemap *pgmap;
> +	} else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) {
> +		struct dev_pagemap *pgmap, *end_pgmap;
>  
>  		pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
> -		if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
> +		end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL);
> +		if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX
> +				&& pfn_t_to_page(pfn)->pgmap == pgmap
> +				&& pfn_t_to_page(end_pfn)->pgmap == pgmap
> +				&& pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr))
> +				&& pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr)))
>  			dax_enabled = true;
>  		put_dev_pagemap(pgmap);
> +		put_dev_pagemap(end_pgmap);
> +
>  	}
>  
>  	if (!dax_enabled) {
>
Dan Williams Feb. 13, 2019, 4:49 p.m. UTC | #2 
On Wed, Feb 13, 2019 at 2:22 AM Jan Kara <jack@suse.cz> wrote:
>
> On Tue 12-02-19 13:24:56, Dan Williams wrote:
> > The checks in __bdev_dax_supported() helped mitigate a potential data
> > corruption bug in the pmem driver's handling of section alignment
> > padding. Strengthen the checks, including checking the end of the range,
> > to validate the dev_pagemap, Xarray entries, and sector-to-pfn
> > translation established for pmem namespaces.
> >
> > Cc: Jan Kara <jack@suse.cz>
> > Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > ---
> >  drivers/dax/super.c |   39 +++++++++++++++++++++++++++++----------
> >  1 file changed, 29 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> > index 6e928f37d084..a27395cfcec6 100644
> > --- a/drivers/dax/super.c
> > +++ b/drivers/dax/super.c
> > @@ -86,12 +86,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
> >  {
> >       struct dax_device *dax_dev;
> >       bool dax_enabled = false;
> > +     pgoff_t pgoff, pgoff_end;
> >       struct request_queue *q;
> > -     pgoff_t pgoff;
> > -     int err, id;
> > -     pfn_t pfn;
> > -     long len;
> >       char buf[BDEVNAME_SIZE];
> > +     void *kaddr, *end_kaddr;
> > +     pfn_t pfn, end_pfn;
> > +     sector_t last_page;
> > +     long len, len2;
> > +     int err, id;
> >
> >       if (blocksize != PAGE_SIZE) {
> >               pr_debug("%s: error: unsupported blocksize for dax\n",
> > @@ -113,6 +115,15 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
> >               return false;
> >       }
> >
> > +     last_page = ALIGN_DOWN(part_nr_sects_read(bdev->bd_part)
> > +                     - PAGE_SIZE / 512, PAGE_SIZE / 512);
>
> Why not just (i_size_read(bdev->bd_inode) - 1) >> PAGE_SHIFT?

Because that would be too elegant and straightforward?

> Otherwise the patch looks good to me.

Thanks, I'll fix up the last page calculation.
diff mbox series

Patch

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 6e928f37d084..a27395cfcec6 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -86,12 +86,14 @@  bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 {
 	struct dax_device *dax_dev;
 	bool dax_enabled = false;
+	pgoff_t pgoff, pgoff_end;
 	struct request_queue *q;
-	pgoff_t pgoff;
-	int err, id;
-	pfn_t pfn;
-	long len;
 	char buf[BDEVNAME_SIZE];
+	void *kaddr, *end_kaddr;
+	pfn_t pfn, end_pfn;
+	sector_t last_page;
+	long len, len2;
+	int err, id;
 
 	if (blocksize != PAGE_SIZE) {
 		pr_debug("%s: error: unsupported blocksize for dax\n",
@@ -113,6 +115,15 @@  bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 		return false;
 	}
 
+	last_page = ALIGN_DOWN(part_nr_sects_read(bdev->bd_part)
+			- PAGE_SIZE / 512, PAGE_SIZE / 512);
+	err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
+	if (err) {
+		pr_debug("%s: error: unaligned partition for dax\n",
+				bdevname(bdev, buf));
+		return false;
+	}
+
 	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
 	if (!dax_dev) {
 		pr_debug("%s: error: device does not support dax\n",
@@ -121,14 +132,15 @@  bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 	}
 
 	id = dax_read_lock();
-	len = dax_direct_access(dax_dev, pgoff, 1, NULL, &pfn);
+	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
+	len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
 	dax_read_unlock(id);
 
 	put_dax(dax_dev);
 
-	if (len < 1) {
+	if (len < 1 || len2 < 1) {
 		pr_debug("%s: error: dax access failed (%ld)\n",
-				bdevname(bdev, buf), len);
+				bdevname(bdev, buf), len < 1 ? len : len2);
 		return false;
 	}
 
@@ -143,13 +155,20 @@  bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 		 */
 		WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
 		dax_enabled = true;
-	} else if (pfn_t_devmap(pfn)) {
-		struct dev_pagemap *pgmap;
+	} else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) {
+		struct dev_pagemap *pgmap, *end_pgmap;
 
 		pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
-		if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
+		end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL);
+		if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX
+				&& pfn_t_to_page(pfn)->pgmap == pgmap
+				&& pfn_t_to_page(end_pfn)->pgmap == pgmap
+				&& pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr))
+				&& pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr)))
 			dax_enabled = true;
 		put_dev_pagemap(pgmap);
+		put_dev_pagemap(end_pgmap);
+
 	}
 
 	if (!dax_enabled) {