Commit c32e5f39 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Dave Chinner
Browse files

vfs: hide file range comparison function 



There are no callers of vfs_dedupe_file_range_compare, so we might as
well make it a static helper and remove the export.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent eca3654e

fs/read_write.c

+91 −96
Original line number Diff line number Diff line
@@ -1752,6 +1752,97 @@ static int generic_remap_check_len(struct inode *inode_in, 
	return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;

}



/*

 * Read a page's worth of file data into the page cache.  Return the page

 * locked.

 */

static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)

{

	struct page *page;



	page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);

	if (IS_ERR(page))

		return page;

	if (!PageUptodate(page)) {

		put_page(page);

		return ERR_PTR(-EIO);

	}

	lock_page(page);

	return page;

}



/*

 * Compare extents of two files to see if they are the same.

 * Caller must have locked both inodes to prevent write races.

 */

static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,

					 struct inode *dest, loff_t destoff,

					 loff_t len, bool *is_same)

{

	loff_t src_poff;

	loff_t dest_poff;

	void *src_addr;

	void *dest_addr;

	struct page *src_page;

	struct page *dest_page;

	loff_t cmp_len;

	bool same;

	int error;



	error = -EINVAL;

	same = true;

	while (len) {

		src_poff = srcoff & (PAGE_SIZE - 1);

		dest_poff = destoff & (PAGE_SIZE - 1);

		cmp_len = min(PAGE_SIZE - src_poff,

			      PAGE_SIZE - dest_poff);

		cmp_len = min(cmp_len, len);

		if (cmp_len <= 0)

			goto out_error;



		src_page = vfs_dedupe_get_page(src, srcoff);

		if (IS_ERR(src_page)) {

			error = PTR_ERR(src_page);

			goto out_error;

		}

		dest_page = vfs_dedupe_get_page(dest, destoff);

		if (IS_ERR(dest_page)) {

			error = PTR_ERR(dest_page);

			unlock_page(src_page);

			put_page(src_page);

			goto out_error;

		}

		src_addr = kmap_atomic(src_page);

		dest_addr = kmap_atomic(dest_page);



		flush_dcache_page(src_page);

		flush_dcache_page(dest_page);



		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))

			same = false;



		kunmap_atomic(dest_addr);

		kunmap_atomic(src_addr);

		unlock_page(dest_page);

		unlock_page(src_page);

		put_page(dest_page);

		put_page(src_page);



		if (!same)

			break;



		srcoff += cmp_len;

		destoff += cmp_len;

		len -= cmp_len;

	}



	*is_same = same;

	return 0;



out_error:

	return error;

}



/*

 * Check that the two inodes are eligible for cloning, the ranges make

 * sense, and then flush all dirty data.  Caller must ensure that the
@@ -1923,102 +2014,6 @@ loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in, 
}

EXPORT_SYMBOL(vfs_clone_file_range);



/*

 * Read a page's worth of file data into the page cache.  Return the page

 * locked.

 */

static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)

{

	struct address_space *mapping;

	struct page *page;

	pgoff_t n;



	n = offset >> PAGE_SHIFT;

	mapping = inode->i_mapping;

	page = read_mapping_page(mapping, n, NULL);

	if (IS_ERR(page))

		return page;

	if (!PageUptodate(page)) {

		put_page(page);

		return ERR_PTR(-EIO);

	}

	lock_page(page);

	return page;

}



/*

 * Compare extents of two files to see if they are the same.

 * Caller must have locked both inodes to prevent write races.

 */

int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,

				  struct inode *dest, loff_t destoff,

				  loff_t len, bool *is_same)

{

	loff_t src_poff;

	loff_t dest_poff;

	void *src_addr;

	void *dest_addr;

	struct page *src_page;

	struct page *dest_page;

	loff_t cmp_len;

	bool same;

	int error;



	error = -EINVAL;

	same = true;

	while (len) {

		src_poff = srcoff & (PAGE_SIZE - 1);

		dest_poff = destoff & (PAGE_SIZE - 1);

		cmp_len = min(PAGE_SIZE - src_poff,

			      PAGE_SIZE - dest_poff);

		cmp_len = min(cmp_len, len);

		if (cmp_len <= 0)

			goto out_error;



		src_page = vfs_dedupe_get_page(src, srcoff);

		if (IS_ERR(src_page)) {

			error = PTR_ERR(src_page);

			goto out_error;

		}

		dest_page = vfs_dedupe_get_page(dest, destoff);

		if (IS_ERR(dest_page)) {

			error = PTR_ERR(dest_page);

			unlock_page(src_page);

			put_page(src_page);

			goto out_error;

		}

		src_addr = kmap_atomic(src_page);

		dest_addr = kmap_atomic(dest_page);



		flush_dcache_page(src_page);

		flush_dcache_page(dest_page);



		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))

			same = false;



		kunmap_atomic(dest_addr);

		kunmap_atomic(src_addr);

		unlock_page(dest_page);

		unlock_page(src_page);

		put_page(dest_page);

		put_page(src_page);



		if (!same)

			break;



		srcoff += cmp_len;

		destoff += cmp_len;

		len -= cmp_len;

	}



	*is_same = same;

	return 0;



out_error:

	return error;

}

EXPORT_SYMBOL(vfs_dedupe_file_range_compare);



loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,

				 struct file *dst_file, loff_t dst_pos,

				 loff_t len, unsigned int remap_flags)

include/linux/fs.h

+0 −3
Original line number Diff line number Diff line
@@ -1853,9 +1853,6 @@ extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in, 
extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,

				   struct file *file_out, loff_t pos_out,

				   loff_t len, unsigned int remap_flags);

extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,

					 struct inode *dest, loff_t destoff,

					 loff_t len, bool *is_same);

extern int vfs_dedupe_file_range(struct file *file,

				 struct file_dedupe_range *same);

extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,

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