[PATCH v2 5/7] dm-integrity: add the "offset" argument

[Mikulas Patocka <mpatocka@redhat.com>]

Make sure that the "data" argument passed to integrity_sector_checksum is
always page-aligned and add an "offset" argument that specifies the
offset from the start of the page. This will enable us to use the
asynchronous hash interface later.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
---
 drivers/md/dm-integrity.c |   49 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 14 deletions(-)

Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c	2025-08-25 15:38:52.000000000 +0200
+++ linux-2.6/drivers/md/dm-integrity.c	2025-08-25 15:40:31.000000000 +0200
@@ -1636,7 +1636,7 @@ static void integrity_end_io(struct bio
 }
 
 static void integrity_sector_checksum(struct dm_integrity_c *ic, sector_t sector,
-				      const char *data, char *result)
+				      const char *data, unsigned offset, char *result)
 {
 	__le64 sector_le = cpu_to_le64(sector);
 	SHASH_DESC_ON_STACK(req, ic->internal_hash);
@@ -1665,7 +1665,7 @@ static void integrity_sector_checksum(st
 		goto failed;
 	}
 
-	r = crypto_shash_update(req, data, ic->sectors_per_block << SECTOR_SHIFT);
+	r = crypto_shash_update(req, data + offset, ic->sectors_per_block << SECTOR_SHIFT);
 	if (unlikely(r < 0)) {
 		dm_integrity_io_error(ic, "crypto_shash_update", r);
 		goto failed;
@@ -1698,6 +1698,15 @@ static void integrity_kunmap(struct dm_i
 	kunmap_local(ptr);
 }
 
+static void *integrity_identity(struct dm_integrity_c *ic, void *data)
+{
+#ifdef CONFIG_DEBUG_SG
+	BUG_ON(offset_in_page(data));
+	BUG_ON(!virt_addr_valid(data));
+#endif
+	return data;
+}
+
 static noinline void integrity_recheck(struct dm_integrity_io *dio, char *checksum)
 {
 	struct bio *bio = dm_bio_from_per_bio_data(dio, sizeof(struct dm_integrity_io));
@@ -1722,6 +1731,7 @@ static noinline void integrity_recheck(s
 			sector_t alignment;
 			char *mem;
 			char *buffer = page_to_virt(page);
+			unsigned int buffer_offset;
 			int r;
 			struct dm_io_request io_req;
 			struct dm_io_region io_loc;
@@ -1739,7 +1749,7 @@ static noinline void integrity_recheck(s
 			alignment &= -alignment;
 			io_loc.sector = round_down(io_loc.sector, alignment);
 			io_loc.count += sector - io_loc.sector;
-			buffer += (sector - io_loc.sector) << SECTOR_SHIFT;
+			buffer_offset = (sector - io_loc.sector) << SECTOR_SHIFT;
 			io_loc.count = round_up(io_loc.count, alignment);
 
 			r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
@@ -1748,7 +1758,7 @@ static noinline void integrity_recheck(s
 				goto free_ret;
 			}
 
-			integrity_sector_checksum(ic, logical_sector, buffer, checksum);
+			integrity_sector_checksum(ic, logical_sector, integrity_identity(ic, buffer), buffer_offset, checksum);
 			r = dm_integrity_rw_tag(ic, checksum, &dio->metadata_block,
 						&dio->metadata_offset, ic->tag_size, TAG_CMP);
 			if (r) {
@@ -1765,7 +1775,7 @@ static noinline void integrity_recheck(s
 			}
 
 			mem = bvec_kmap_local(&bv);
-			memcpy(mem + pos, buffer, ic->sectors_per_block << SECTOR_SHIFT);
+			memcpy(mem + pos, buffer + buffer_offset, ic->sectors_per_block << SECTOR_SHIFT);
 			kunmap_local(mem);
 
 			pos += ic->sectors_per_block << SECTOR_SHIFT;
@@ -1852,7 +1862,7 @@ again:
 			pos = 0;
 			checksums_ptr = checksums;
 			do {
-				integrity_sector_checksum(ic, sector, mem + bv_copy.bv_offset + pos, checksums_ptr);
+				integrity_sector_checksum(ic, sector, mem, bv_copy.bv_offset + pos, checksums_ptr);
 				checksums_ptr += ic->tag_size;
 				sectors_to_process -= ic->sectors_per_block;
 				pos += ic->sectors_per_block << SECTOR_SHIFT;
@@ -2123,14 +2133,16 @@ retry_kmap:
 
 				if (ic->internal_hash) {
 					unsigned int digest_size = ic->internal_hash_digestsize;
+					void *js_page = integrity_identity(ic, (char *)js - offset_in_page(js));
+					unsigned js_offset = offset_in_page(js);
 
 					if (unlikely(digest_size > ic->tag_size)) {
 						char checksums_onstack[HASH_MAX_DIGESTSIZE];
 
-						integrity_sector_checksum(ic, logical_sector, (char *)js, checksums_onstack);
+						integrity_sector_checksum(ic, logical_sector, js_page, js_offset, checksums_onstack);
 						memcpy(journal_entry_tag(ic, je), checksums_onstack, ic->tag_size);
 					} else
-						integrity_sector_checksum(ic, logical_sector, (char *)js, journal_entry_tag(ic, je));
+						integrity_sector_checksum(ic, logical_sector, js_page, js_offset, journal_entry_tag(ic, je));
 				}
 
 				journal_entry_set_sector(je, logical_sector);
@@ -2506,7 +2518,7 @@ skip_spinlock:
 			const char *mem = integrity_kmap(ic, bv.bv_page);
 			if (ic->tag_size < ic->tuple_size)
 				memset(dio->integrity_payload + pos + ic->tag_size, 0, ic->tuple_size - ic->tuple_size);
-			integrity_sector_checksum(ic, dio->bio_details.bi_iter.bi_sector, mem + bv.bv_offset, dio->integrity_payload + pos);
+			integrity_sector_checksum(ic, dio->bio_details.bi_iter.bi_sector, mem, bv.bv_offset, dio->integrity_payload + pos);
 			integrity_kunmap(ic, mem);
 			pos += ic->tuple_size;
 			bio_advance_iter_single(bio, &dio->bio_details.bi_iter, ic->sectors_per_block << SECTOR_SHIFT);
@@ -2586,7 +2598,7 @@ static void dm_integrity_inline_recheck(
 		}
 		bio_put(outgoing_bio);
 
-		integrity_sector_checksum(ic, dio->bio_details.bi_iter.bi_sector, outgoing_data, digest);
+		integrity_sector_checksum(ic, dio->bio_details.bi_iter.bi_sector, integrity_identity(ic, outgoing_data), 0, digest);
 		if (unlikely(crypto_memneq(digest, dio->integrity_payload, min(ic->internal_hash_digestsize, ic->tag_size)))) {
 			DMERR_LIMIT("%pg: Checksum failed at sector 0x%llx",
 				ic->dev->bdev, dio->bio_details.bi_iter.bi_sector);
@@ -2624,7 +2636,7 @@ static int dm_integrity_end_io(struct dm
 				char digest[HASH_MAX_DIGESTSIZE];
 				struct bio_vec bv = bio_iter_iovec(bio, dio->bio_details.bi_iter);
 				char *mem = integrity_kmap(ic, bv.bv_page);
-				integrity_sector_checksum(ic, dio->bio_details.bi_iter.bi_sector, mem + bv.bv_offset, digest);
+				integrity_sector_checksum(ic, dio->bio_details.bi_iter.bi_sector, mem, bv.bv_offset, digest);
 				if (unlikely(crypto_memneq(digest, dio->integrity_payload + pos,
 						min(ic->internal_hash_digestsize, ic->tag_size)))) {
 					integrity_kunmap(ic, mem);
@@ -2899,9 +2911,12 @@ static void do_journal_write(struct dm_i
 #endif
 				    ic->internal_hash) {
 					char test_tag[MAX_T(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
+					struct journal_sector *js = access_journal_data(ic, i, l);
+					void *js_page = integrity_identity(ic, (char *)js - offset_in_page(js));
+					unsigned js_offset = offset_in_page(js);
 
 					integrity_sector_checksum(ic, sec + ((l - j) << ic->sb->log2_sectors_per_block),
-								  (char *)access_journal_data(ic, i, l), test_tag);
+								  js_page, js_offset, test_tag);
 					if (unlikely(crypto_memneq(test_tag, journal_entry_tag(ic, je2), ic->tag_size))) {
 						dm_integrity_io_error(ic, "tag mismatch when replaying journal", -EILSEQ);
 						dm_audit_log_target(DM_MSG_PREFIX, "integrity-replay-journal", ic->ti, 0);
@@ -3094,7 +3109,10 @@ next_chunk:
 
 	t = recalc_tags;
 	for (i = 0; i < n_sectors; i += ic->sectors_per_block) {
-		integrity_sector_checksum(ic, logical_sector + i, recalc_buffer + (i << SECTOR_SHIFT), t);
+		void *ptr = recalc_buffer + (i << SECTOR_SHIFT);
+		void *ptr_page = integrity_identity(ic, (char *)ptr - offset_in_page(ptr));
+		unsigned ptr_offset = offset_in_page(ptr);
+		integrity_sector_checksum(ic, logical_sector + i, ptr_page, ptr_offset, t);
 		t += ic->tag_size;
 	}
 
@@ -3214,8 +3232,11 @@ next_chunk:
 
 	t = recalc_tags;
 	for (i = 0; i < range.n_sectors; i += ic->sectors_per_block) {
+		void *ptr = recalc_buffer + (i << SECTOR_SHIFT);
+		void *ptr_page = integrity_identity(ic, (char *)ptr - offset_in_page(ptr));
+		unsigned ptr_offset = offset_in_page(ptr);
 		memset(t, 0, ic->tuple_size);
-		integrity_sector_checksum(ic, range.logical_sector + i, recalc_buffer + (i << SECTOR_SHIFT), t);
+		integrity_sector_checksum(ic, range.logical_sector + i, ptr_page, ptr_offset, t);
 		t += ic->tuple_size;
 	}