[PATCH v4 2/9] block: blk-crypto: introduce blk_crypto_bio_sectors_alignment()

[Satya Tangirala <satyaprateek2357@gmail.com>]

From: Satya Tangirala <satyat@google.com>

The size of any bio must be aligned to the data unit size of the bio crypt
context (if it exists) of that bio. This must also be ensured whenever a
bio is split. Introduce blk_crypto_bio_sectors_alignment() that returns the
required alignment in sectors. The number of sectors passed to any call of
bio_split() must be aligned to blk_crypto_bio_sectors_alignment().

Signed-off-by: Satya Tangirala <satyat@google.com>
---
 block/blk-crypto-internal.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h
index 0d36aae538d7..81d10cf950ce 100644
--- a/block/blk-crypto-internal.h
+++ b/block/blk-crypto-internal.h
@@ -60,6 +60,18 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
 	return rq->crypt_ctx;
 }
 
+/*
+ * Return the number of sectors to which the size of this bio (and any bios
+ * split from it) must be aligned based on its encryption context.
+ */
+static inline unsigned int blk_crypto_bio_sectors_alignment(struct bio *bio)
+{
+	if (!bio_has_crypt_ctx(bio))
+		return 1;
+	return bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size >>
+								SECTOR_SHIFT;
+}
+
 #else /* CONFIG_BLK_INLINE_ENCRYPTION */
 
 static inline bool bio_crypt_rq_ctx_compatible(struct request *rq,
@@ -93,6 +105,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
 	return false;
 }
 
+static inline unsigned int blk_crypto_bio_sectors_alignment(struct bio *bio)
+{
+	return 1;
+}
+
 #endif /* CONFIG_BLK_INLINE_ENCRYPTION */
 
 void __bio_crypt_advance(struct bio *bio, unsigned int bytes);
-- 
2.25.1