File bsc-1206791-01-drbd-add-comments-explaining-rem... of Package drbd

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File bsc-1206791-01-drbd-add-comments-explaining-removal-of-bdi-congesti.patch of Package drbd (Revision 27e3dc909ac4c09b4039876f83990d04)

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From c89bb88cde9349b11dbf255e762203c626e70d30 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20B=C3=B6hmwalder?=
 <christoph.boehmwalder@linbit.com>
Date: Mon, 3 Oct 2022 14:49:55 +0200
Subject: [PATCH] drbd: add comments explaining removal of bdi congestion

The bdi congestion tracking framework was removed, so this leaves a few
confusing places where we just blindly set a "congested" flag to false.
Add some comments, briefly explaining the history of why it is like
that.

---
by heming.zhao@suse.com:
bsc-1201335_06-bdi.patch followed upstream patch b807a2c5e0e2, which
removed s->dev_lower_blocked from device_to_statistics(). But drbd main
branch latest code still keep s->dev_lower_blocked, I used this patch
to restore s->dev_lower_blocked.

---

diff --git a/drbd/drbd_nl.c b/drbd/drbd_nl.c
index 020372fdb258..6a2afd184ae6 100644
--- a/drbd/drbd_nl.c
+++ b/drbd/drbd_nl.c
@@ -5514,6 +5514,10 @@ static void device_to_statistics(struct device_statistics *s,
 		spin_unlock_irq(&md->uuid_lock);
 
 		s->dev_disk_flags = md->flags;
+		/* originally, this used the bdi congestion framework,
+		 * but that was removed in linux 5.18.
+		 * so just never report the lower device as congested. */
+		s->dev_lower_blocked = false;
 		put_ldev(device);
 	}
 	s->dev_size = get_capacity(device->vdisk);
diff --git a/drbd/drbd_req.c b/drbd/drbd_req.c
index e5098bf8b26c..02dbc61946ca 100644
--- a/drbd/drbd_req.c
+++ b/drbd/drbd_req.c
@@ -1275,6 +1275,9 @@ static bool remote_due_to_read_balancing(struct drbd_device *device,
 
 	switch (rbm) {
 	case RB_CONGESTED_REMOTE:
+		/* originally, this used the bdi congestion framework,
+		 * but that was removed in linux 5.18.
+		 * so just never report the lower device as congested. */
 		return false;
 	case RB_LEAST_PENDING:
 		return atomic_read(&device->local_cnt) >
-- 
2.26.2

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File bsc-1206791-01-drbd-add-comments-explaining-removal-of-bdi-congesti.patch of Package drbd (Revision 27e3dc909ac4c09b4039876f83990d04)

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