dm-verity: don't crash if panic_on_corruption is not selected

If the user sets panic_on_error and doesn't set panic_on_corruption,
dm-verity should not panic on data mismatch. But, currently it panics,
because it treats data mismatch as I/O error.

This commit fixes the logic so that if there is data mismatch and
panic_on_corruption or restart_on_corruption is not selected, the system
won't restart or panic.

Signed-off-by: Mikulas Patocka <[email protected]>
Reviewed-by: Sami Tolvanen <[email protected]>
Fixes: f811b83 ("dm-verity: introduce the options restart_on_error and panic_on_error")

Author: Mikulas Patocka

drivers/md/dm-verity-target.c

@@ -356,9 +356,9 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 		else if (verity_handle_err(v,
 					   DM_VERITY_BLOCK_TYPE_METADATA,
 					   hash_block)) {
-			struct bio *bio =
-				dm_bio_from_per_bio_data(io,
-							 v->ti->per_io_data_size);
+			struct bio *bio;
+			io->had_mismatch = true;
+			bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 			dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 					 block, 0);
 			r = -EIO;
@@ -482,6 +482,7 @@ static int verity_handle_data_hash_mismatch(struct dm_verity *v,
 		return -EIO; /* Error correction failed; Just return error */
 
 	if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
+		io->had_mismatch = true;
 		dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
 		return -EIO;
 	}
@@ -606,6 +607,7 @@ static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 
 	if (unlikely(status != BLK_STS_OK) &&
 	    unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
+	    !io->had_mismatch &&
 	    !verity_is_system_shutting_down()) {
 		if (v->error_mode == DM_VERITY_MODE_PANIC) {
 			panic("dm-verity device has I/O error");
@@ -779,6 +781,7 @@ static int verity_map(struct dm_target *ti, struct bio *bio)
 	io->orig_bi_end_io = bio->bi_end_io;
 	io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 	io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
+	io->had_mismatch = false;
 
 	bio->bi_end_io = verity_end_io;
 	bio->bi_private = io;

drivers/md/dm-verity.h

@@ -92,6 +92,7 @@ struct dm_verity_io {
 	sector_t block;
 	unsigned int n_blocks;
 	bool in_bh;
+	bool had_mismatch;
 
 	struct work_struct work;
 	struct work_struct bh_work;