[Devel] [RFC PATCH vz9 v6 47/62] dm-ploop: disable metadata writeback delay

[Alexander Atanasov]

Delayed metadata writeback results in a hang, disable
it until it is fixed. Pios end in the waiting list of
md and get stuck there never to complete.

Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index c88359677ea4..6e4d6f862135 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -817,9 +817,10 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
 	/* holes bit map requires bat_lock */
 	spin_lock_irqsave(&ploop->bat_lock, flags);
 	spin_lock(&md->md_lock);
+#ifdef PLOOP_DELAYWB
 	if (piwb->type == PIWB_TYPE_ALLOC)
 		goto skip_apply;
-
+#endif
 	for (; i < last; i++) {
 		if (piwb->type == PIWB_TYPE_DISCARD) {
 			ploop_piwb_discard_completed(ploop, success, i + off, dst_clu[i]);
@@ -836,7 +837,9 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
 			ploop_hole_set_bit(i + off, ploop);
 		}
 	}
+#ifdef PLOOP_DELAYWB
 skip_apply:
+#endif
 
 	WARN_ON_ONCE(!test_bit(MD_WRITEBACK, &md->status));
 	clear_bit(MD_WRITEBACK, &md->status);
@@ -1187,8 +1190,10 @@ static int ploop_alloc_cluster(struct ploop *ploop, struct ploop_index_wb *piwb,
 
 	to = piwb->kmpage;
 	WRITE_ONCE(to[clu], *dst_clu);
+#ifdef PLOOP_DELAYWB
 	to = piwb->md->kmpage;
 	WRITE_ONCE(to[clu], *dst_clu);
+#endif
 out:
 	return ret;
 }
@@ -1481,6 +1486,7 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
 	WARN_ON(to[clu]);
 	WRITE_ONCE(to[clu], cow->dst_clu);
 
+#ifdef PLOOP_DELAYWB
 	spin_lock_irqsave(&md->md_lock, flags);
 	to = md->kmpage;
 	WRITE_ONCE(to[clu], cow->dst_clu);
@@ -1488,7 +1494,7 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
 	spin_unlock_irqrestore(&md->md_lock, flags);
 
 	ploop_md_up_prio(ploop, md);
-
+#endif
 	/* Prevent double clearing of holes_bitmap bit on complete_cow() */
 	cow->dst_clu = BAT_ENTRY_NONE;
 	spin_lock_irq(&ploop->deferred_lock);
@@ -1918,7 +1924,9 @@ static inline int ploop_submit_metadata_writeback(struct ploop *ploop, int force
 	 */
 	llist_for_each_safe(pos, t, ll_wb_batch) {
 		md = list_entry((struct list_head *)pos, typeof(*md), wb_link);
-		if (!llist_empty(&md->wait_llist) || force || test_bit(MD_HIGHPRIO, &md->status) ||
+		/* XXX: fixme delay results in a hang - TBD */
+		if (1 || !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));
-- 
2.43.0