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From:   Satya Tangirala <satyaprateek2357@gmail.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 <satyaprateek2357@gmail.com>,
        Satya Tangirala <satyat@google.com>
Subject: [PATCH v4 1/9] block: introduce blk_ksm_is_empty()
Date:   Tue,  6 Jul 2021 22:29:35 -0700
Message-Id: <20210707052943.3960-2-satyaprateek2357@gmail.com>
In-Reply-To: <20210707052943.3960-1-satyaprateek2357@gmail.com>
References: <20210707052943.3960-1-satyaprateek2357@gmail.com>
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From: Satya Tangirala <satyat@google.com>

This function checks if a given keyslot manager supports any encryption
mode/data unit size combination (and returns true if there is no such
supported combination). Helps clean up code a little.

Signed-off-by: Satya Tangirala <satyat@google.com>
---
 block/keyslot-manager.c         | 31 +++++++++++++++++++++++++++++++
 drivers/md/dm-table.c           | 11 +----------
 include/linux/keyslot-manager.h |  2 ++
 3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
index 2c4a55bea6ca..4d0794506d43 100644
--- a/block/keyslot-manager.c
+++ b/block/keyslot-manager.c
@@ -437,6 +437,37 @@ void blk_ksm_destroy(struct blk_keyslot_manager *ksm)
 }
 EXPORT_SYMBOL_GPL(blk_ksm_destroy);
 
+/*
+ * Returns true iff @ksm doesn't support any crypto capabilities if
+ * @dus_allowed_mask were applied to each crypto mode of @ksm.
+ */
+static inline bool blk_ksm_is_empty_mask(struct blk_keyslot_manager *ksm,
+					 unsigned long dus_allowed_mask)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ksm->crypto_modes_supported); i++) {
+		if (ksm->crypto_modes_supported[i] & dus_allowed_mask)
+			return false;
+	}
+
+	return true;
+}
+
+/**
+ * blk_ksm_is_empty() - Checks if the keyslot manager has any crypto
+ *			capabilities at all.
+ * @ksm: The input keyslot manager to check
+ *
+ * Return: true if @ksm doesn't have any crypto capabilities at all, and
+ *	   false otherwise.
+ */
+bool blk_ksm_is_empty(struct blk_keyslot_manager *ksm)
+{
+	return blk_ksm_is_empty_mask(ksm, ~0);
+}
+EXPORT_SYMBOL_GPL(blk_ksm_is_empty);
+
 bool blk_ksm_register(struct blk_keyslot_manager *ksm, struct request_queue *q)
 {
 	if (blk_integrity_queue_supports_integrity(q)) {
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index ee47a332b462..29cbfc3e3c4b 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1295,7 +1295,6 @@ static int dm_table_construct_keyslot_manager(struct dm_table *t)
 	struct blk_keyslot_manager *ksm;
 	struct dm_target *ti;
 	unsigned int i;
-	bool ksm_is_empty = true;
 
 	dksm = kmalloc(sizeof(*dksm), GFP_KERNEL);
 	if (!dksm)
@@ -1332,15 +1331,7 @@ static int dm_table_construct_keyslot_manager(struct dm_table *t)
 	 * If the new KSM doesn't actually support any crypto modes, we may as
 	 * well represent it with a NULL ksm.
 	 */
-	ksm_is_empty = true;
-	for (i = 0; i < ARRAY_SIZE(ksm->crypto_modes_supported); i++) {
-		if (ksm->crypto_modes_supported[i]) {
-			ksm_is_empty = false;
-			break;
-		}
-	}
-
-	if (ksm_is_empty) {
+	if (blk_ksm_is_empty(ksm)) {
 		dm_destroy_keyslot_manager(ksm);
 		ksm = NULL;
 	}
diff --git a/include/linux/keyslot-manager.h b/include/linux/keyslot-manager.h
index a27605e2f826..0f09b4f310f7 100644
--- a/include/linux/keyslot-manager.h
+++ b/include/linux/keyslot-manager.h
@@ -106,6 +106,8 @@ void blk_ksm_reprogram_all_keys(struct blk_keyslot_manager *ksm);
 
 void blk_ksm_destroy(struct blk_keyslot_manager *ksm);
 
+bool blk_ksm_is_empty(struct blk_keyslot_manager *ksm);
+
 void blk_ksm_intersect_modes(struct blk_keyslot_manager *parent,
 			     const struct blk_keyslot_manager *child);
 
-- 
2.25.1