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Commit 679c8bd3 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Vishal Verma
Browse files

dax: export a low-level __dax_zero_page_range helper 



This allows XFS to perform zeroing using the iomap infrastructure and
avoid buffer heads.

Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
[vishal: fix conflicts with dax-error-handling]
Signed-off-by: default avatarVishal Verma <vishal.l.verma@intel.com>
parent 3dc29161

fs/dax.c

+20 −15
Original line number Diff line number Diff line
@@ -947,6 +947,23 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) 
}

EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);



int __dax_zero_page_range(struct block_device *bdev, sector_t sector,

		unsigned int offset, unsigned int length)

{

	struct blk_dax_ctl dax = {

		.sector		= sector,

		.size		= PAGE_SIZE,

	};



	if (dax_map_atomic(bdev, &dax) < 0)

		return PTR_ERR(dax.addr);

	clear_pmem(dax.addr + offset, length);

	wmb_pmem();

	dax_unmap_atomic(bdev, &dax);

	return 0;

}

EXPORT_SYMBOL_GPL(__dax_zero_page_range);



/**

 * dax_zero_page_range - zero a range within a page of a DAX file

 * @inode: The file being truncated
@@ -982,23 +999,11 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, 
	bh.b_bdev = inode->i_sb->s_bdev;

	bh.b_size = PAGE_SIZE;

	err = get_block(inode, index, &bh, 0);

	if (err < 0)

	if (err < 0 || !buffer_written(&bh))

		return err;

	if (buffer_written(&bh)) {

		struct block_device *bdev = bh.b_bdev;

		struct blk_dax_ctl dax = {

			.sector = to_sector(&bh, inode),

			.size = PAGE_SIZE,

		};



		if (dax_map_atomic(bdev, &dax) < 0)

			return PTR_ERR(dax.addr);

		clear_pmem(dax.addr + offset, length);

		wmb_pmem();

		dax_unmap_atomic(bdev, &dax);

	}



	return 0;

	return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode),

			offset, length);

}

EXPORT_SYMBOL_GPL(dax_zero_page_range);

include/linux/dax.h

+7 −0
Original line number Diff line number Diff line
@@ -14,12 +14,19 @@ int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t); 


#ifdef CONFIG_FS_DAX

struct page *read_dax_sector(struct block_device *bdev, sector_t n);

int __dax_zero_page_range(struct block_device *bdev, sector_t sector,

		unsigned int offset, unsigned int length);

#else

static inline struct page *read_dax_sector(struct block_device *bdev,

		sector_t n)

{

	return ERR_PTR(-ENXIO);

}

static inline int __dax_zero_page_range(struct block_device *bdev,

		sector_t sector, unsigned int offset, unsigned int length)

{

	return -ENXIO;

}

#endif



#ifdef CONFIG_TRANSPARENT_HUGEPAGE