diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index a8c95eee91b7..006b2f5173de 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -438,7 +438,8 @@ static void io_submit_add_bh(struct ext4_io_submit *io,
 			     struct inode *inode,
 			     struct folio *folio,
 			     struct folio *io_folio,
-			     struct buffer_head *bh)
+			     struct buffer_head *bh,
+		             size_t io_off)
 {
 	if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
 			   !fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
@@ -449,7 +450,7 @@ static void io_submit_add_bh(struct ext4_io_submit *io,
 		io_submit_init_bio(io, bh);
 		io->io_bio->bi_write_hint = inode->i_write_hint;
 	}
-	if (!bio_add_folio(io->io_bio, io_folio, bh->b_size, bh_offset(bh)))
+	if (!bio_add_folio(io->io_bio, io_folio, bh->b_size, io_off))
 		goto submit_and_retry;
 	wbc_account_cgroup_owner(io->io_wbc, folio, bh->b_size);
 	io->io_next_block++;
@@ -585,9 +586,20 @@ int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *folio,
 
 	/* Now submit buffers to write */
 	do {
+		size_t io_off;
+
 		if (!buffer_async_write(bh))
 			continue;
-		io_submit_add_bh(io, inode, folio, io_folio, bh);
+		/*
+		 * When io_folio is a single-page bounce buffer (fscrypt),
+		 * normalise to PAGE_SIZE to handle all block sizes correctly.
+		 * Using 0 would break sub-page block sizes (e.g. 1024-byte
+		 * blocks) where multiple bh offsets exist within one page
+		 */
+		io_off = (io_folio == folio)
+			 ? bh_offset(bh)
+			 : bh_offset(bh) % PAGE_SIZE;
+		io_submit_add_bh(io, inode, folio, io_folio, bh, io_off);
 	} while ((bh = bh->b_this_page) != head);
 
 	return 0;