ntfs: Do not kmap page cache pages for compression

These pages are accessed through vmap; they are not accessed
by calling page_address(), so they do not need to be kmapped.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

Author: Matthew Wilcox (Oracle)

fs/ntfs3/frecord.c

@@ -2407,9 +2407,6 @@ int ni_read_frame(struct ntfs_inode *ni, u64 frame_vbo, struct page **pages,
 	 * To simplify decompress algorithm do vmap for source
 	 * and target pages.
 	 */
-	for (i = 0; i < pages_per_frame; i++)
-		kmap(pages[i]);
-
 	frame_size = pages_per_frame << PAGE_SHIFT;
 	frame_mem = vmap(pages, pages_per_frame, VM_MAP, PAGE_KERNEL);
 	if (!frame_mem) {
@@ -2655,7 +2652,6 @@ int ni_read_frame(struct ntfs_inode *ni, u64 frame_vbo, struct page **pages,
 out:
 	for (i = 0; i < pages_per_frame; i++) {
 		pg = pages[i];
-		kunmap(pg);
 		SetPageUptodate(pg);
 	}
 
@@ -2742,9 +2738,6 @@ int ni_write_frame(struct ntfs_inode *ni, struct page **pages,
 		goto out1;
 	}
 
-	for (i = 0; i < pages_per_frame; i++)
-		kmap(pages[i]);
-
 	/* Map in-memory frame for read-only. */
 	frame_mem = vmap(pages, pages_per_frame, VM_MAP, PAGE_KERNEL_RO);
 	if (!frame_mem) {
@@ -2810,11 +2803,7 @@ int ni_write_frame(struct ntfs_inode *ni, struct page **pages,
 
 out3:
 	vunmap(frame_mem);
-
 out2:
-	for (i = 0; i < pages_per_frame; i++)
-		kunmap(pages[i]);
-
 	vunmap(frame_ondisk);
 out1:
 	for (i = 0; i < pages_per_frame; i++) {