dm integrity: clear the journal on suspend

There was a problem that a user burned a dm-integrity image on CDROM
and could not activate it because it had a non-empty journal.

Fix this problem by flushing the journal (done by the previous commit)
and clearing the journal (done by this commit). Once the journal is
cleared, dm-integrity won't attempt to replay it on the next
activation.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-integrity.c

@@ -263,6 +263,7 @@ struct dm_integrity_c {
 
 	struct completion crypto_backoff;
 
+	bool wrote_to_journal;
 	bool journal_uptodate;
 	bool just_formatted;
 	bool recalculate_flag;
@@ -2375,6 +2376,8 @@ static void integrity_commit(struct work_struct *w)
 	if (!commit_sections)
 		goto release_flush_bios;
 
+	ic->wrote_to_journal = true;
+
 	i = commit_start;
 	for (n = 0; n < commit_sections; n++) {
 		for (j = 0; j < ic->journal_section_entries; j++) {
@@ -3100,6 +3103,14 @@ static void dm_integrity_postsuspend(struct dm_target *ti)
 		queue_work(ic->writer_wq, &ic->writer_work);
 		drain_workqueue(ic->writer_wq);
 		dm_integrity_flush_buffers(ic, true);
+		if (ic->wrote_to_journal) {
+			init_journal(ic, ic->free_section,
+				     ic->journal_sections - ic->free_section, ic->commit_seq);
+			if (ic->free_section) {
+				init_journal(ic, 0, ic->free_section,
+					     next_commit_seq(ic->commit_seq));
+			}
+		}
 	}
 
 	if (ic->mode == 'B') {
@@ -3127,6 +3138,8 @@ static void dm_integrity_resume(struct dm_target *ti)
 
 	DEBUG_print("resume\n");
 
+	ic->wrote_to_journal = false;
+
 	if (ic->provided_data_sectors != old_provided_data_sectors) {
 		if (ic->provided_data_sectors > old_provided_data_sectors &&
 		    ic->mode == 'B' &&