btrfs: check-integrity: drop kmap/kunmap for block pages

The pages in block_ctx have never been allocated from highmem (in
btrfsic_read_block) so the mapping is pointless and can be removed.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/check-integrity.c

@@ -1509,10 +1509,8 @@ static void btrfsic_release_block_ctx(struct btrfsic_block_data_ctx *block_ctx)
 		/* Pages must be unmapped in reverse order */
 		while (num_pages > 0) {
 			num_pages--;
-			if (block_ctx->datav[num_pages]) {
-				kunmap_local(block_ctx->datav[num_pages]);
+			if (block_ctx->datav[num_pages])
 				block_ctx->datav[num_pages] = NULL;
-			}
 			if (block_ctx->pagev[num_pages]) {
 				__free_page(block_ctx->pagev[num_pages]);
 				block_ctx->pagev[num_pages] = NULL;
@@ -1589,7 +1587,7 @@ static int btrfsic_read_block(struct btrfsic_state *state,
 		i = j;
 	}
 	for (i = 0; i < num_pages; i++)
-		block_ctx->datav[i] = kmap_local_page(block_ctx->pagev[i]);
+		block_ctx->datav[i] = page_address(block_ctx->pagev[i]);
 
 	return block_ctx->len;
 }
@@ -2654,7 +2652,7 @@ static void __btrfsic_submit_bio(struct bio *bio)
 
 		bio_for_each_segment(bvec, bio, iter) {
 			BUG_ON(bvec.bv_len != PAGE_SIZE);
-			mapped_datav[i] = kmap_local_page(bvec.bv_page);
+			mapped_datav[i] = page_address(bvec.bv_page);
 			i++;
 
 			if (dev_state->state->print_mask &
@@ -2667,9 +2665,6 @@ static void __btrfsic_submit_bio(struct bio *bio)
 					      mapped_datav, segs,
 					      bio, &bio_is_patched,
 					      bio->bi_opf);
-		/* Unmap in reverse order */
-		for (--i; i >= 0; i--)
-			kunmap_local(mapped_datav[i]);
 		kfree(mapped_datav);
 	} else if (NULL != dev_state && (bio->bi_opf & REQ_PREFLUSH)) {
 		if (dev_state->state->print_mask &