bcache: fix 64 bit crc truncation

Note: this is effectively an on disk format change, but it turns out crc64 for
data checksums was just broken before.

2 files changed, 37 insertions, 9 deletions

diff --git a/drivers/md/bcache/checksum.c b/drivers/md/bcache/checksum.c
index beae0b26e570..b618f08e3b63 100644
--- a/drivers/md/bcache/checksum.c
+++ b/drivers/md/bcache/checksum.c
@@ -129,6 +129,34 @@ u64 bch_crc64_update(u64 crc, const void *_data, size_t len)
 	return crc;
 }
 
+static u64 bch_checksum_init(unsigned type)
+{
+	switch (type) {
+	case BCH_CSUM_NONE:
+		return 0;
+	case BCH_CSUM_CRC32C:
+		return U32_MAX;
+	case BCH_CSUM_CRC64:
+		return U64_MAX;
+	default:
+		BUG();
+	}
+}
+
+static u64 bch_checksum_final(unsigned type, u64 crc)
+{
+	switch (type) {
+	case BCH_CSUM_NONE:
+		return 0;
+	case BCH_CSUM_CRC32C:
+		return crc ^ U32_MAX;
+	case BCH_CSUM_CRC64:
+		return crc ^ U64_MAX;
+	default:
+		BUG();
+	}
+}
+
 u64 bch_checksum_update(unsigned type, u64 crc, const void *data, size_t len)
 {
 	switch (type) {
@@ -145,18 +173,18 @@ u64 bch_checksum_update(unsigned type, u64 crc, const void *data, size_t len)
 
 u64 bch_checksum(unsigned type, const void *data, size_t len)
 {
-	u64 crc = 0xffffffffffffffffULL;
+	u64 crc = bch_checksum_init(type);
 
 	crc = bch_checksum_update(type, crc, data, len);
 
-	return crc ^ 0xffffffffffffffffULL;
+	return bch_checksum_final(type, crc);
 }
 
-u32 bch_checksum_bio(struct bio *bio, unsigned type)
+u64 bch_checksum_bio(struct bio *bio, unsigned type)
 {
 	struct bio_vec bv;
 	struct bvec_iter iter;
-	u32 csum = U32_MAX;
+	u64 crc = bch_checksum_init(type);
 
 	if (type == BCH_CSUM_NONE)
 		return 0;
@@ -164,11 +192,11 @@ u32 bch_checksum_bio(struct bio *bio, unsigned type)
 	bio_for_each_segment(bv, bio, iter) {
 		void *p = kmap_atomic(bv.bv_page);
 
-		csum = bch_checksum_update(type, csum,
-					   p + bv.bv_offset,
-					   bv.bv_len);
+		crc = bch_checksum_update(type, crc,
+					  p + bv.bv_offset,
+					  bv.bv_len);
 		kunmap_atomic(p);
 	}
 
-	return csum ^= U32_MAX;
+	return bch_checksum_final(type, crc);
 }
diff --git a/drivers/md/bcache/checksum.h b/drivers/md/bcache/checksum.h
index 169a24a527a8..f84f9884d466 100644
--- a/drivers/md/bcache/checksum.h
+++ b/drivers/md/bcache/checksum.h
@@ -5,7 +5,7 @@ u64 bch_crc64_update(uint64_t, const void *, size_t);
 
 u64 bch_checksum_update(unsigned, u64, const void *, size_t);
 u64 bch_checksum(unsigned, const void *, size_t);
-u32 bch_checksum_bio(struct bio *, unsigned);
+u64 bch_checksum_bio(struct bio *, unsigned);
 
 /*
  * This is used for various on disk data structures - cache_sb, prio_set, bset,