From 41c526c5af46d4c4dab7f72c99000b7fac0b9702 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Mon, 24 Feb 2020 10:20:30 +0100
Subject: [PATCH] dm writecache: verify watermark during resume
Git-commit: 41c526c5af46d4c4dab7f72c99000b7fac0b9702
Patch-mainline: v5.6-rc5
References: git fixes (block drivers)

Verify the watermark upon resume - so that if the target is reloaded
with lower watermark, it will start the cleanup process immediately.

(Coly Li: rebased for fixes/linux-4.12 code base)

Fixes: 48debafe4f2f ("dm: add writecache target")
Cc: stable@vger.kernel.org # 4.18+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/dm-writecache.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -633,6 +633,12 @@ static void writecache_add_to_freelist(s
 	wc->freelist_size++;
 }
 
+static inline void writecache_verify_watermark(struct dm_writecache *wc)
+{
+	if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
+		queue_work(wc->writeback_wq, &wc->writeback_work);
+}
+
 static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc)
 {
 	struct wc_entry *e;
@@ -654,8 +660,8 @@ static struct wc_entry *writecache_pop_f
 		list_del(&e->lru);
 	}
 	wc->freelist_size--;
-	if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
-		queue_work(wc->writeback_wq, &wc->writeback_work);
+
+	writecache_verify_watermark(wc);
 
 	return e;
 }
@@ -970,6 +976,8 @@ erase_this:
 		writecache_commit_flushed(wc, false);
 	}
 
+	writecache_verify_watermark(wc);
+
 	wc_unlock(wc);
 }