diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index cfdc643191862a..5d01f092ae13f2 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -82,6 +82,14 @@ static inline unsigned int btrfs_compress_level(unsigned int type_level)
 	return ((type_level & 0xF0) >> 4);
 }
 
+/* @range_end must be exclusive. */
+static inline u32 btrfs_calc_input_length(u64 range_end, u64 cur)
+{
+	u64 page_end = round_down(cur, PAGE_SIZE) + PAGE_SIZE;
+
+	return min(range_end, page_end) - cur;
+}
+
 int __init btrfs_init_compress(void);
 void __cold btrfs_exit_compress(void);
 
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 30971dd741e2df..ee80d064b9549c 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -20,6 +20,8 @@
 #include <linux/refcount.h>
 #include "btrfs_inode.h"
 #include "compression.h"
+#include "fs.h"
+#include "subpage.h"
 
 /* workspace buffer size for s390 zlib hardware support */
 #define ZLIB_DFLTCC_BUF_SIZE    (4 * PAGE_SIZE)
@@ -108,6 +110,7 @@ int zlib_compress_folios(struct list_head *ws, struct address_space *mapping,
 	unsigned long len = *total_out;
 	unsigned long nr_dest_folios = *out_folios;
 	const unsigned long max_out = nr_dest_folios * PAGE_SIZE;
+	const u64 orig_end = start + len;
 
 	*out_folios = 0;
 	*total_out = 0;
@@ -153,6 +156,10 @@ int zlib_compress_folios(struct list_head *ws, struct address_space *mapping,
 			if (in_buf_folios > 1) {
 				int i;
 
+				/* S390 hardware acceleration path, not subpage. */
+				ASSERT(!btrfs_is_subpage(
+						inode_to_fs_info(mapping->host),
+						mapping));
 				for (i = 0; i < in_buf_folios; i++) {
 					if (data_in) {
 						kunmap_local(data_in);
@@ -167,9 +174,14 @@ int zlib_compress_folios(struct list_head *ws, struct address_space *mapping,
 					copy_page(workspace->buf + i * PAGE_SIZE,
 						  data_in);
 					start += PAGE_SIZE;
+					workspace->strm.avail_in =
+						(in_buf_folios << PAGE_SHIFT);
 				}
 				workspace->strm.next_in = workspace->buf;
 			} else {
+				unsigned int pg_off;
+				unsigned int cur_len;
+
 				if (data_in) {
 					kunmap_local(data_in);
 					folio_put(in_folio);
@@ -179,12 +191,13 @@ int zlib_compress_folios(struct list_head *ws, struct address_space *mapping,
 						start, &in_folio);
 				if (ret < 0)
 					goto out;
-				data_in = kmap_local_folio(in_folio, 0);
+				pg_off = offset_in_page(start);
+				cur_len = btrfs_calc_input_length(orig_end, start);
+				data_in = kmap_local_folio(in_folio, pg_off);
 				start += PAGE_SIZE;
 				workspace->strm.next_in = data_in;
+				workspace->strm.avail_in = cur_len;
 			}
-			workspace->strm.avail_in = min(bytes_left,
-						       (unsigned long) workspace->buf_size);
 		}
 
 		ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 2a079561b2b10b..05cf7cebc17c85 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -389,7 +389,10 @@ int zstd_compress_folios(struct list_head *ws, struct address_space *mapping,
 	unsigned long tot_out = 0;
 	unsigned long len = *total_out;
 	const unsigned long nr_dest_folios = *out_folios;
+	const u64 orig_end = start + len;
 	unsigned long max_out = nr_dest_folios * PAGE_SIZE;
+	unsigned int pg_off;
+	unsigned int cur_len;
 	zstd_parameters params = zstd_get_btrfs_parameters(workspace->req_level,
 							   len);
 
@@ -415,9 +418,11 @@ int zstd_compress_folios(struct list_head *ws, struct address_space *mapping,
 	ret = btrfs_compress_filemap_get_folio(mapping, start, &in_folio);
 	if (ret < 0)
 		goto out;
-	workspace->in_buf.src = kmap_local_folio(in_folio, 0);
+	pg_off = offset_in_page(start);
+	cur_len = btrfs_calc_input_length(orig_end, start);
+	workspace->in_buf.src = kmap_local_folio(in_folio, pg_off);
 	workspace->in_buf.pos = 0;
-	workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
+	workspace->in_buf.size = cur_len;
 
 	/* Allocate and map in the output buffer */
 	out_folio = btrfs_alloc_compr_folio();
@@ -494,14 +499,16 @@ int zstd_compress_folios(struct list_head *ws, struct address_space *mapping,
 			kunmap_local(workspace->in_buf.src);
 			workspace->in_buf.src = NULL;
 			folio_put(in_folio);
-			start += PAGE_SIZE;
-			len -= PAGE_SIZE;
+			start += cur_len;
+			len -= cur_len;
 			ret = btrfs_compress_filemap_get_folio(mapping, start, &in_folio);
 			if (ret < 0)
 				goto out;
-			workspace->in_buf.src = kmap_local_folio(in_folio, 0);
+			pg_off = offset_in_page(start);
+			cur_len = btrfs_calc_input_length(orig_end, start);
+			workspace->in_buf.src = kmap_local_folio(in_folio, pg_off);
 			workspace->in_buf.pos = 0;
-			workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
+			workspace->in_buf.size = cur_len;
 		}
 	}
 	while (1) {