Revert "btrfs: compression: drop kmap/kunmap from generic helpers"

This reverts commit 4c2bf27.

The kmaps in compression code are still needed and cause crashes on
32bit machines (ARM, x86). Reproducible eg. by running fstest btrfs/004
with enabled LZO or ZSTD compression.

Link: https://lore.kernel.org/all/CAJCQCtT+OuemovPO7GZk8Y8=qtOObr0XTDp8jh4OHD6y84AFxw@mail.gmail.com/
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214839
Signed-off-by: David Sterba <dsterba@suse.com>

Author: kdave

fs/btrfs/compression.c

@@ -172,9 +172,10 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
 		/* Hash through the page sector by sector */
 		for (pg_offset = 0; pg_offset < bytes_left;
 		     pg_offset += sectorsize) {
-			kaddr = page_address(page);
+			kaddr = kmap_atomic(page);
 			crypto_shash_digest(shash, kaddr + pg_offset,
 					    sectorsize, csum);
+			kunmap_atomic(kaddr);
 
 			if (memcmp(&csum, cb_sum, csum_size) != 0) {
 				btrfs_print_data_csum_error(inode, disk_start,

fs/btrfs/inode.c

@@ -287,8 +287,9 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
 			cur_size = min_t(unsigned long, compressed_size,
 				       PAGE_SIZE);
 
-			kaddr = page_address(cpage);
+			kaddr = kmap_atomic(cpage);
 			write_extent_buffer(leaf, kaddr, ptr, cur_size);
+			kunmap_atomic(kaddr);
 
 			i++;
 			ptr += cur_size;