Commit f605a263 authored by Vivek Goyal's avatar Vivek Goyal Committed by Dan Williams
Browse files

dax, pmem: Add a dax operation zero_page_range 



Add a dax operation zero_page_range, to zero a page. This will also clear any
known poison in the page being zeroed.

As of now, zeroing of one page is allowed in a single call. There
are no callers which are trying to zero more than a page in a single call.
Once we grow the callers which zero more than a page in single call, we
can add that support. Primary reason for not doing that yet is that this
will add little complexity in dm implementation where a range might be
spanning multiple underlying targets and one will have to split the range
into multiple sub ranges and call zero_page_range() on individual targets.

Suggested-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Reviewed-by: default avatarPankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: https://lore.kernel.org/r/20200228163456.1587-3-vgoyal@redhat.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 5d64efe7

drivers/dax/super.c

+20 −0
Original line number Diff line number Diff line
@@ -344,6 +344,26 @@ size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, 
}

EXPORT_SYMBOL_GPL(dax_copy_to_iter);



int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,

			size_t nr_pages)

{

	if (!dax_alive(dax_dev))

		return -ENXIO;



	if (!dax_dev->ops->zero_page_range)

		return -EOPNOTSUPP;

	/*

	 * There are no callers that want to zero more than one page as of now.

	 * Once users are there, this check can be removed after the

	 * device mapper code has been updated to split ranges across targets.

	 */

	if (nr_pages != 1)

		return -EIO;



	return dax_dev->ops->zero_page_range(dax_dev, pgoff, nr_pages);

}

EXPORT_SYMBOL_GPL(dax_zero_page_range);



#ifdef CONFIG_ARCH_HAS_PMEM_API

void arch_wb_cache_pmem(void *addr, size_t size);

void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)

drivers/nvdimm/pmem.c

+11 −0
Original line number Diff line number Diff line
@@ -282,6 +282,16 @@ static const struct block_device_operations pmem_fops = { 
	.revalidate_disk =	nvdimm_revalidate_disk,

};



static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,

				    size_t nr_pages)

{

	struct pmem_device *pmem = dax_get_private(dax_dev);



	return blk_status_to_errno(pmem_do_write(pmem, ZERO_PAGE(0), 0,

				   PFN_PHYS(pgoff) >> SECTOR_SHIFT,

				   PAGE_SIZE));

}



static long pmem_dax_direct_access(struct dax_device *dax_dev,

		pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)

{
@@ -313,6 +323,7 @@ static const struct dax_operations pmem_dax_ops = { 
	.dax_supported = generic_fsdax_supported,

	.copy_from_iter = pmem_copy_from_iter,

	.copy_to_iter = pmem_copy_to_iter,

	.zero_page_range = pmem_dax_zero_page_range,

};



static const struct attribute_group *pmem_attribute_groups[] = {

include/linux/dax.h

+4 −0
Original line number Diff line number Diff line
@@ -34,6 +34,8 @@ struct dax_operations { 
	/* copy_to_iter: required operation for fs-dax direct-i/o */

	size_t (*copy_to_iter)(struct dax_device *, pgoff_t, void *, size_t,

			struct iov_iter *);

	/* zero_page_range: required operation. Zero page range   */

	int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);

};



extern struct attribute_group dax_attribute_group;
@@ -199,6 +201,8 @@ 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,

		size_t bytes, struct iov_iter *i);

int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,

			size_t nr_pages);

void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);



ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,

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