[Devel] [RFC PATCH vz9 v5 44/49] dm-ploop: make ploop_submit_metadata_writeback return number of requests sent

[Alexander Atanasov]

We need to wait for write back to complete to issue pending flushes.
To know if we have to wait return numer of pios submitted.

https://virtuozzo.atlassian.net/browse/VSTOR-91821
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index acff0d7c5a20..c7c07234571b 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1911,7 +1911,7 @@ static int inline ploop_runners_have_pending(struct ploop *ploop)
 }
 #endif
 
-static void ploop_submit_metadata_writeback(struct ploop *ploop, int force)
+static int ploop_submit_metadata_writeback(struct ploop *ploop, int force)
 {
 	unsigned long flags;
 	LIST_HEAD(ll_skipped);
@@ -1919,19 +1919,26 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop, int force)
 	struct llist_node *pos, *t;
 	struct llist_node *ll_wb_batch;
 	unsigned long timeout = jiffies;
+	int ret;
 
 	/* Lock here to protect against md_inflight counting */
 	spin_lock_irqsave(&ploop->bat_lock, flags);
 	ll_wb_batch = llist_del_all(&ploop->wb_batch_llist);
 	spin_unlock_irqrestore(&ploop->bat_lock, flags);
+	if (!ll_wb_batch) {
+		return 0;
+	}
+
+	ret = 0;
+
 	/*
 	 * Pages are set dirty so no one must touch lists
 	 * if new md entries are dirtied they are added at the start of the list
 	 */
-	llist_for_each_safe(pos, t, ll_wb_batch ) {
+	llist_for_each_safe(pos, t, ll_wb_batch) {
 		md = list_entry((struct list_head *)pos, typeof(*md), wb_link);
-		if (test_bit(MD_HIGHPRIO, &md->status) || time_before(md->dirty_timeout, timeout)
-		    || ploop->force_md_writeback) {
+		if (!llist_empty(&md->wait_llist) || force || test_bit(MD_HIGHPRIO, &md->status) ||
+			time_before(md->dirty_timeout, timeout)) {
 			/* L1L2 mustn't be redirtyed, when wb in-flight! */
 			WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
 			WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
@@ -1939,11 +1946,14 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop, int force)
 			clear_bit(MD_DIRTY, &md->status);
 			clear_bit(MD_HIGHPRIO, &md->status);
 			ploop_index_wb_submit(ploop, md->piwb);
+			ret++;
 		} else {
 			printk(KERN_ERR "abwbl\n");
+			INIT_LIST_HEAD(&md->wb_link);
 			llist_add((struct llist_node *)&md->wb_link, &ploop->wb_batch_llist);
 		}
 	}
+	return ret;
 }
 
 static void process_ploop_fsync_work(struct ploop *ploop, struct llist_node *llflush_pios)
-- 
2.43.0