From: Mikulas Patocka <mpatocka@redhat.com>
Date: Sun, 22 Mar 2020 20:42:27 +0100
Subject: [PATCH] dm integrity: improve discard in journal mode
Git-commit: 31843edab7cb3924006544b901c9cab33941b684
Patch-mainline: v5.7-rc1
References: bsc#1175995,jsc#SLE-15608

When we discard something that is present in the journal, we flush the
journal first, so that discarded blocks are not overwritten by the journal
content.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/md/dm-integrity.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 21eb35c606be..b989d109d55d 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1943,6 +1943,7 @@ static void dm_integrity_map_continue(struct dm_integrity_io *dio, bool from_map
 	unsigned journal_section, journal_entry;
 	unsigned journal_read_pos;
 	struct completion read_comp;
+	bool discard_retried = false;
 	bool need_sync_io = ic->internal_hash && dio->op == REQ_OP_READ;
 	if (unlikely(dio->op == REQ_OP_DISCARD) && ic->mode != 'D')
 		need_sync_io = true;
@@ -2059,6 +2060,21 @@ static void dm_integrity_map_continue(struct dm_integrity_io *dio, bool from_map
 			}
 		}
 	}
+	if (ic->mode == 'J' && likely(dio->op == REQ_OP_DISCARD) && !discard_retried) {
+		sector_t next_sector;
+		unsigned new_pos = find_journal_node(ic, dio->range.logical_sector, &next_sector);
+		if (unlikely(new_pos != NOT_FOUND) ||
+		    unlikely(next_sector < dio->range.logical_sector - dio->range.n_sectors)) {
+			remove_range_unlocked(ic, &dio->range);
+			spin_unlock_irq(&ic->endio_wait.lock);
+			queue_work(ic->commit_wq, &ic->commit_work);
+			flush_workqueue(ic->commit_wq);
+			queue_work(ic->writer_wq, &ic->writer_work);
+			flush_workqueue(ic->writer_wq);
+			discard_retried = true;
+			goto lock_retry;
+		}
+	}
 	spin_unlock_irq(&ic->endio_wait.lock);
 
 	if (unlikely(journal_read_pos != NOT_FOUND)) {
-- 
2.16.4