drbd: fix max_bio_size to be unsigned

We capped our max_bio_size respectively max_hw_sectors with
min_t(int, lower level limit, our limit);
unfortunately, some drivers, e.g. the kvm virtio block driver, initialize their
limits to "-1U", and that is of course a smaller "int" value than our limit.

Impact: we started to request 16 MB resync requests,
which lead to protocol error and a reconnect loop.

Fix all relevant constants and parameters to be unsigned int.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -1136,8 +1136,8 @@ struct drbd_conf {
 	int rs_in_flight; /* resync sectors in flight (to proxy, in proxy and from proxy) */
 	int rs_planed;    /* resync sectors already planned */
 	atomic_t ap_in_flight; /* App sectors in flight (waiting for ack) */
-	int peer_max_bio_size;
+	unsigned int peer_max_bio_size;
-	int local_max_bio_size;
+	unsigned int local_max_bio_size;
 };
 
 static inline struct drbd_conf *minor_to_mdev(unsigned int minor)
@@ -1441,9 +1441,9 @@ struct bm_extent {
  * hash table. */
 #define HT_SHIFT 8
 #define DRBD_MAX_BIO_SIZE (1U<<(9+HT_SHIFT))
-#define DRBD_MAX_BIO_SIZE_SAFE (1 << 12)       /* Works always = 4k */
+#define DRBD_MAX_BIO_SIZE_SAFE (1U << 12)       /* Works always = 4k */
 
-#define DRBD_MAX_SIZE_H80_PACKET (1 << 15) /* The old header only allows packets up to 32Kib data */
+#define DRBD_MAX_SIZE_H80_PACKET (1U << 15) /* The old header only allows packets up to 32Kib data */
 
 /* Number of elements in the app_reads_hash */
 #define APP_R_HSIZE 15

drivers/block/drbd/drbd_main.c

@@ -2209,7 +2209,8 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 {
 	struct p_sizes p;
 	sector_t d_size, u_size;
-	int q_order_type, max_bio_size;
+	int q_order_type;
+	unsigned int max_bio_size;
 	int ok;
 
 	if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
@@ -2218,7 +2219,7 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 		u_size = mdev->ldev->dc.disk_size;
 		q_order_type = drbd_queue_order_type(mdev);
 		max_bio_size = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
-		max_bio_size = min_t(int, max_bio_size, DRBD_MAX_BIO_SIZE);
+		max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE);
 		put_ldev(mdev);
 	} else {
 		d_size = 0;
@@ -2229,7 +2230,7 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
 
 	/* Never allow old drbd (up to 8.3.7) to see more than 32KiB */
 	if (mdev->agreed_pro_version <= 94)
-		max_bio_size = min_t(int, max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+		max_bio_size = min(max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
 
 	p.d_size = cpu_to_be64(d_size);
 	p.u_size = cpu_to_be64(u_size);
@@ -3981,9 +3982,9 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 
 	spin_lock_irq(&mdev->req_lock);
 	if (mdev->state.conn < C_CONNECTED) {
-		int peer;
+		unsigned int peer;
 		peer = be32_to_cpu(buffer->la_peer_max_bio_size);
-		peer = max_t(int, peer, DRBD_MAX_BIO_SIZE_SAFE);
+		peer = max(peer, DRBD_MAX_BIO_SIZE_SAFE);
 		mdev->peer_max_bio_size = peer;
 	}
 	spin_unlock_irq(&mdev->req_lock);

drivers/block/drbd/drbd_nl.c

@@ -801,8 +801,8 @@ static int drbd_check_al_size(struct drbd_conf *mdev)
 static void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_size)
 {
 	struct request_queue * const q = mdev->rq_queue;
-	int max_hw_sectors = max_bio_size >> 9;
+	unsigned int max_hw_sectors = max_bio_size >> 9;
-	int max_segments = 0;
+	unsigned int max_segments = 0;
 
 	if (get_ldev_if_state(mdev, D_ATTACHING)) {
 		struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;
@@ -835,7 +835,7 @@ static void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_
 
 void drbd_reconsider_max_bio_size(struct drbd_conf *mdev)
 {
-	int now, new, local, peer;
+	unsigned int now, new, local, peer;
 
 	now = queue_max_hw_sectors(mdev->rq_queue) << 9;
 	local = mdev->local_max_bio_size; /* Eventually last known value, from volatile memory */
@@ -846,13 +846,14 @@ void drbd_reconsider_max_bio_size(struct drbd_conf *mdev)
 		mdev->local_max_bio_size = local;
 		put_ldev(mdev);
 	}
+	local = min(local, DRBD_MAX_BIO_SIZE);
 
 	/* We may ignore peer limits if the peer is modern enough.
 	   Because new from 8.3.8 onwards the peer can use multiple
 	   BIOs for a single peer_request */
 	if (mdev->state.conn >= C_CONNECTED) {
 		if (mdev->agreed_pro_version < 94) {
-			peer = min_t(int, mdev->peer_max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+			peer = min(mdev->peer_max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
 			/* Correct old drbd (up to 8.3.7) if it believes it can do more than 32KiB */
 		} else if (mdev->agreed_pro_version == 94)
 			peer = DRBD_MAX_SIZE_H80_PACKET;
@@ -860,10 +861,10 @@ void drbd_reconsider_max_bio_size(struct drbd_conf *mdev)
 			peer = DRBD_MAX_BIO_SIZE;
 	}
 
-	new = min_t(int, local, peer);
+	new = min(local, peer);
 
 	if (mdev->state.role == R_PRIMARY && new < now)
-		dev_err(DEV, "ASSERT FAILED new < now; (%d < %d)\n", new, now);
+		dev_err(DEV, "ASSERT FAILED new < now; (%u < %u)\n", new, now);
 
 	if (new != now)
 		dev_info(DEV, "max BIO size = %u\n", new);