From: Jan Kara <[email protected]>
DM was calling generic_fsdax_supported() to determine whether a device
referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
they don't have to duplicate common generic checks. High level code
should call dax_supported() helper which that calls into appropriate
helper for the particular device. This problem manifested itself as
kernel messages:
dm-3: error: dax access failed (-95)
when lvm2-testsuite run in cases where a DM device was stacked on top of
another DM device.
Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
Cc: <[email protected]>
Tested-by: Adrian Huang <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Acked-by: Mike Snitzer <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
---
Changes since v1 [1]:
- Add missing dax_read_lock() around dax_supported()
[1]: http://lore.kernel.org/r/[email protected]
drivers/dax/super.c | 4 ++++
drivers/md/dm-table.c | 10 +++++++---
include/linux/dax.h | 11 +++++++++--
3 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e5767c83ea23..b6284c5cae0a 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -325,11 +325,15 @@ EXPORT_SYMBOL_GPL(dax_direct_access);
bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
int blocksize, sector_t start, sector_t len)
{
+ if (!dax_dev)
+ return false;
+
if (!dax_alive(dax_dev))
return false;
return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len);
}
+EXPORT_SYMBOL_GPL(dax_supported);
size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
size_t bytes, struct iov_iter *i)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 5edc3079e7c1..229f461e7def 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -860,10 +860,14 @@ EXPORT_SYMBOL_GPL(dm_table_set_type);
int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
sector_t start, sector_t len, void *data)
{
- int blocksize = *(int *) data;
+ int blocksize = *(int *) data, id;
+ bool rc;
- return generic_fsdax_supported(dev->dax_dev, dev->bdev, blocksize,
- start, len);
+ id = dax_read_lock();
+ rc = dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
+ dax_read_unlock(id);
+
+ return rc;
}
/* Check devices support synchronous DAX */
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 6904d4e0b2e0..9f916326814a 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -130,6 +130,8 @@ static inline bool generic_fsdax_supported(struct dax_device *dax_dev,
return __generic_fsdax_supported(dax_dev, bdev, blocksize, start,
sectors);
}
+bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
+ int blocksize, sector_t start, sector_t len);
static inline void fs_put_dax(struct dax_device *dax_dev)
{
@@ -157,6 +159,13 @@ static inline bool generic_fsdax_supported(struct dax_device *dax_dev,
return false;
}
+static inline bool dax_supported(struct dax_device *dax_dev,
+ struct block_device *bdev, int blocksize, sector_t start,
+ sector_t len)
+{
+ return false;
+}
+
static inline void fs_put_dax(struct dax_device *dax_dev)
{
}
@@ -195,8 +204,6 @@ bool dax_alive(struct dax_device *dax_dev);
void *dax_get_private(struct dax_device *dax_dev);
long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
void **kaddr, pfn_t *pfn);
-bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
- int blocksize, sector_t start, sector_t len);
size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
size_t bytes, struct iov_iter *i);
size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
On Thu, Sep 17, 2020 at 10:30:03PM -0700, Dan Williams wrote:
> From: Jan Kara <[email protected]>
>
> DM was calling generic_fsdax_supported() to determine whether a device
> referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
> they don't have to duplicate common generic checks. High level code
> should call dax_supported() helper which that calls into appropriate
> helper for the particular device. This problem manifested itself as
> kernel messages:
>
> dm-3: error: dax access failed (-95)
>
> when lvm2-testsuite run in cases where a DM device was stacked on top of
> another DM device.
Is there somewhere where it is documented which of:
bdev_dax_supported, generic_fsdax_supported, and dax_supported
one is supposed to use for a given circumstance?
I guess the last two can test a given range w/ blocksize; the first one
only does blocksize; and the middle one also checks with whatever fs
might be mounted? <shrug>
(I ask because it took me a while to figure out how to revert correctly
the brokenness in rc3-5 that broke my nightly dax fstesting.)
--D
>
> Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
> Cc: <[email protected]>
> Tested-by: Adrian Huang <[email protected]>
> Signed-off-by: Jan Kara <[email protected]>
> Acked-by: Mike Snitzer <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>
> ---
> Changes since v1 [1]:
> - Add missing dax_read_lock() around dax_supported()
>
> [1]: http://lore.kernel.org/r/[email protected]
>
> drivers/dax/super.c | 4 ++++
> drivers/md/dm-table.c | 10 +++++++---
> include/linux/dax.h | 11 +++++++++--
> 3 files changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index e5767c83ea23..b6284c5cae0a 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -325,11 +325,15 @@ EXPORT_SYMBOL_GPL(dax_direct_access);
> bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> int blocksize, sector_t start, sector_t len)
> {
> + if (!dax_dev)
> + return false;
> +
> if (!dax_alive(dax_dev))
> return false;
>
> return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len);
> }
> +EXPORT_SYMBOL_GPL(dax_supported);
>
> size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
> size_t bytes, struct iov_iter *i)
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 5edc3079e7c1..229f461e7def 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -860,10 +860,14 @@ EXPORT_SYMBOL_GPL(dm_table_set_type);
> int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
> sector_t start, sector_t len, void *data)
> {
> - int blocksize = *(int *) data;
> + int blocksize = *(int *) data, id;
> + bool rc;
>
> - return generic_fsdax_supported(dev->dax_dev, dev->bdev, blocksize,
> - start, len);
> + id = dax_read_lock();
> + rc = dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
> + dax_read_unlock(id);
> +
> + return rc;
> }
>
> /* Check devices support synchronous DAX */
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 6904d4e0b2e0..9f916326814a 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -130,6 +130,8 @@ static inline bool generic_fsdax_supported(struct dax_device *dax_dev,
> return __generic_fsdax_supported(dax_dev, bdev, blocksize, start,
> sectors);
> }
> +bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> + int blocksize, sector_t start, sector_t len);
>
> static inline void fs_put_dax(struct dax_device *dax_dev)
> {
> @@ -157,6 +159,13 @@ static inline bool generic_fsdax_supported(struct dax_device *dax_dev,
> return false;
> }
>
> +static inline bool dax_supported(struct dax_device *dax_dev,
> + struct block_device *bdev, int blocksize, sector_t start,
> + sector_t len)
> +{
> + return false;
> +}
> +
> static inline void fs_put_dax(struct dax_device *dax_dev)
> {
> }
> @@ -195,8 +204,6 @@ bool dax_alive(struct dax_device *dax_dev);
> void *dax_get_private(struct dax_device *dax_dev);
> long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
> void **kaddr, pfn_t *pfn);
> -bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> - int blocksize, sector_t start, sector_t len);
> size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
> size_t bytes, struct iov_iter *i);
> size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
>
> --
> dm-devel mailing list
> [email protected]
> https://www.redhat.com/mailman/listinfo/dm-devel
>
On Fri, Sep 18, 2020 at 8:31 AM Darrick J. Wong <[email protected]> wrote:
>
> On Thu, Sep 17, 2020 at 10:30:03PM -0700, Dan Williams wrote:
> > From: Jan Kara <[email protected]>
> >
> > DM was calling generic_fsdax_supported() to determine whether a device
> > referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
> > they don't have to duplicate common generic checks. High level code
> > should call dax_supported() helper which that calls into appropriate
> > helper for the particular device. This problem manifested itself as
> > kernel messages:
> >
> > dm-3: error: dax access failed (-95)
> >
> > when lvm2-testsuite run in cases where a DM device was stacked on top of
> > another DM device.
>
> Is there somewhere where it is documented which of:
>
> bdev_dax_supported, generic_fsdax_supported, and dax_supported
>
> one is supposed to use for a given circumstance?
generic_fsdax_supported should be private to device drivers populating
their dax_operations. I think it deserves a rename at this point.
dax_supported() knows how to route through multiple layers of stacked
block-devices to ask the "is dax supported" question at each level.
> I guess the last two can test a given range w/ blocksize; the first one
> only does blocksize; and the middle one also checks with whatever fs
> might be mounted? <shrug>
>
> (I ask because it took me a while to figure out how to revert correctly
> the brokenness in rc3-5 that broke my nightly dax fstesting.)
Again, apologies for that.
On Fri, 18 Sep 2020 at 11:18, Dan Williams <[email protected]> wrote:
>
> From: Jan Kara <[email protected]>
>
> DM was calling generic_fsdax_supported() to determine whether a device
> referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
> they don't have to duplicate common generic checks. High level code
> should call dax_supported() helper which that calls into appropriate
> helper for the particular device. This problem manifested itself as
> kernel messages:
>
> dm-3: error: dax access failed (-95)
>
> when lvm2-testsuite run in cases where a DM device was stacked on top of
> another DM device.
>
> Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
> Cc: <[email protected]>
> Tested-by: Adrian Huang <[email protected]>
> Signed-off-by: Jan Kara <[email protected]>
> Acked-by: Mike Snitzer <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>
> ---
> Changes since v1 [1]:
> - Add missing dax_read_lock() around dax_supported()
>
> [1]: http://lore.kernel.org/r/[email protected]
>
> drivers/dax/super.c | 4 ++++
> drivers/md/dm-table.c | 10 +++++++---
> include/linux/dax.h | 11 +++++++++--
> 3 files changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index e5767c83ea23..b6284c5cae0a 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -325,11 +325,15 @@ EXPORT_SYMBOL_GPL(dax_direct_access);
> bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> int blocksize, sector_t start, sector_t len)
> {
> + if (!dax_dev)
> + return false;
> +
> if (!dax_alive(dax_dev))
> return false;
>
> return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len);
> }
> +EXPORT_SYMBOL_GPL(dax_supported);
arm build error while building with allmodconfig.
../drivers/dax/super.c:325:6: error: redefinition of ‘dax_supported’
325 | bool dax_supported(struct dax_device *dax_dev, struct
block_device *bdev,
| ^~~~~~~~~~~~~
In file included from ../drivers/dax/super.c:16:
../include/linux/dax.h:162:20: note: previous definition of
‘dax_supported’ was here
162 | static inline bool dax_supported(struct dax_device *dax_dev,
| ^~~~~~~~~~~~~
make[3]: *** [../scripts/Makefile.build:283: drivers/dax/super.o] Error 1
Reported-by: Naresh Kamboju <[email protected]>
Ref:
https://builds.tuxbuild.com/IO690jFQDp0qP9zFuWBqpA/build.log
On Mon 21-09-20 11:23:07, Naresh Kamboju wrote:
> On Fri, 18 Sep 2020 at 11:18, Dan Williams <[email protected]> wrote:
> >
> > From: Jan Kara <[email protected]>
> >
> > DM was calling generic_fsdax_supported() to determine whether a device
> > referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
> > they don't have to duplicate common generic checks. High level code
> > should call dax_supported() helper which that calls into appropriate
> > helper for the particular device. This problem manifested itself as
> > kernel messages:
> >
> > dm-3: error: dax access failed (-95)
> >
> > when lvm2-testsuite run in cases where a DM device was stacked on top of
> > another DM device.
> >
> > Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
> > Cc: <[email protected]>
> > Tested-by: Adrian Huang <[email protected]>
> > Signed-off-by: Jan Kara <[email protected]>
> > Acked-by: Mike Snitzer <[email protected]>
> > Signed-off-by: Dan Williams <[email protected]>
> > ---
> > Changes since v1 [1]:
> > - Add missing dax_read_lock() around dax_supported()
> >
> > [1]: http://lore.kernel.org/r/[email protected]
> >
> > drivers/dax/super.c | 4 ++++
> > drivers/md/dm-table.c | 10 +++++++---
> > include/linux/dax.h | 11 +++++++++--
> > 3 files changed, 20 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> > index e5767c83ea23..b6284c5cae0a 100644
> > --- a/drivers/dax/super.c
> > +++ b/drivers/dax/super.c
> > @@ -325,11 +325,15 @@ EXPORT_SYMBOL_GPL(dax_direct_access);
> > bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> > int blocksize, sector_t start, sector_t len)
> > {
> > + if (!dax_dev)
> > + return false;
> > +
> > if (!dax_alive(dax_dev))
> > return false;
> >
> > return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len);
> > }
> > +EXPORT_SYMBOL_GPL(dax_supported);
>
> arm build error while building with allmodconfig.
>
> ../drivers/dax/super.c:325:6: error: redefinition of ‘dax_supported’
> 325 | bool dax_supported(struct dax_device *dax_dev, struct
> block_device *bdev,
> | ^~~~~~~~~~~~~
> In file included from ../drivers/dax/super.c:16:
> ../include/linux/dax.h:162:20: note: previous definition of
> ‘dax_supported’ was here
> 162 | static inline bool dax_supported(struct dax_device *dax_dev,
> | ^~~~~~~~~~~~~
> make[3]: *** [../scripts/Makefile.build:283: drivers/dax/super.o] Error 1
>
> Reported-by: Naresh Kamboju <[email protected]>
>
> Ref:
> https://builds.tuxbuild.com/IO690jFQDp0qP9zFuWBqpA/build.log
Thanks for report! Attached patch should fix the build (at least I've
tested it with CONFIG_DAX && CONFIG_FS_DAX, CONFIG_DAX && !CONFIG_FS_DAX,
and !CONFIG_DAX cases). Dan can you please merge the fix?
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR