Commit e2ec5128 authored by Jan Kara's avatar Jan Kara Committed by Dan Williams
Browse files

dm: Call proper helper to determine dax support 



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: 7bf7eac8 ("dax: Arrange for dax_supported check to span multiple devices")
Cc: <stable@vger.kernel.org>
Tested-by: default avatarAdrian Huang <ahuang12@lenovo.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Reported-by: default avatarkernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/160061715195.13131.5503173247632041975.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 02186d88

drivers/dax/super.c

+4 −0
Original line number Diff line number Diff line
@@ -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)

drivers/md/dm-table.c

+7 −3
Original line number Diff line number Diff line
@@ -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 */

include/linux/dax.h

+20 −2
Original line number Diff line number Diff line
@@ -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)

{

}
@@ -189,14 +198,23 @@ static inline void dax_unlock_page(struct page *page, dax_entry_t cookie) 
}

#endif



#if IS_ENABLED(CONFIG_DAX)

int dax_read_lock(void);

void dax_read_unlock(int id);

#else

static inline int dax_read_lock(void)

{

	return 0;

}



static inline void dax_read_unlock(int id)

{

}

#endif /* CONFIG_DAX */

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,

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