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Date:   Fri,  4 Jun 2021 19:58:52 +0000
In-Reply-To: <20210604195900.2096121-1-satyat@google.com>
Message-Id: <20210604195900.2096121-3-satyat@google.com>
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Subject: [PATCH v3 02/10] block: blk-crypto: introduce blk_crypto_bio_sectors_alignment()
From:   Satya Tangirala <satyat@google.com>
To:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Jens Axboe <axboe@kernel.dk>, Eric Biggers <ebiggers@google.com>,
        Satya Tangirala <satyat@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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 | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h
index 0d36aae538d7..7f1535cc7e7c 100644
--- a/block/blk-crypto-internal.h
+++ b/block/blk-crypto-internal.h
@@ -60,6 +60,21 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
 	return rq->crypt_ctx;
 }
 
+/*
+ * Returns the alignment requirement for the number of sectors in this bio based
+ * on its bi_crypt_context. Any bios split from this bio must follow this
+ * alignment requirement as well. Note that a bio must contain a whole number of
+ * crypto data units (which is selected by the submitter of bio), since
+ * encryption/decryption can only be performed on a complete crypto data unit.
+ */
+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 +108,11 @@ 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);
-- 
2.32.0.rc1.229.g3e70b5a671-goog