[dm-devel] [PATCH 7/7] dm integrity: improve discard in journal mode

[Mikulas Patocka]

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 at redhat.com>

---
 drivers/md/dm-integrity.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c	2020-03-20 17:41:22.000000000 +0100
+++ linux-2.6/drivers/md/dm-integrity.c	2020-03-22 17:30:24.000000000 +0100
@@ -1941,6 +1941,7 @@ static void dm_integrity_map_continue(st
 	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;
@@ -2057,6 +2058,20 @@ offload_to_thread:
 			}
 		}
 	}
+	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)) {