dm-verity: introduce the options restart_on_error and panic_on_error

This patch introduces the options restart_on_error and panic_on_error on
dm-verity.

Previously, restarting on error was handled by the patch
e6a3531d, but Google engineers wanted to
have a special option for it.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Suggested-by: Will Drewry <wad@chromium.org>

drivers/md/dm-verity-target.c

@@ -36,11 +36,13 @@
 #define DM_VERITY_OPT_LOGGING		"ignore_corruption"
 #define DM_VERITY_OPT_RESTART		"restart_on_corruption"
 #define DM_VERITY_OPT_PANIC		"panic_on_corruption"
+#define DM_VERITY_OPT_ERROR_RESTART	"restart_on_error"
+#define DM_VERITY_OPT_ERROR_PANIC	"panic_on_error"
 #define DM_VERITY_OPT_IGN_ZEROES	"ignore_zero_blocks"
 #define DM_VERITY_OPT_AT_MOST_ONCE	"check_at_most_once"
 #define DM_VERITY_OPT_TASKLET_VERIFY	"try_verify_in_tasklet"
 
-#define DM_VERITY_OPTS_MAX		(4 + DM_VERITY_OPTS_FEC + \
+#define DM_VERITY_OPTS_MAX		(5 + DM_VERITY_OPTS_FEC + \
 					 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
 
 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
@@ -583,6 +585,11 @@ static inline bool verity_is_system_shutting_down(void)
 		|| system_state == SYSTEM_RESTART;
 }
 
+static void restart_io_error(struct work_struct *w)
+{
+	kernel_restart("dm-verity device has I/O error");
+}
+
 /*
  * End one "io" structure with a given error.
  */
@@ -597,6 +604,23 @@ static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 	if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
 		verity_fec_finish_io(io);
 
+	if (unlikely(status != BLK_STS_OK) &&
+	    unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
+	    !verity_is_system_shutting_down()) {
+		if (v->error_mode == DM_VERITY_MODE_PANIC) {
+			panic("dm-verity device has I/O error");
+		}
+		if (v->error_mode == DM_VERITY_MODE_RESTART) {
+			static DECLARE_WORK(restart_work, restart_io_error);
+			queue_work(v->verify_wq, &restart_work);
+			/*
+			 * We deliberately don't call bio_endio here, because
+			 * the machine will be restarted anyway.
+			 */
+			return;
+		}
+	}
+
 	bio_endio(bio);
 }
 
@@ -805,6 +829,8 @@ static void verity_status(struct dm_target *ti, status_type_t type,
 				DMEMIT("%02x", v->salt[x]);
 		if (v->mode != DM_VERITY_MODE_EIO)
 			args++;
+		if (v->error_mode != DM_VERITY_MODE_EIO)
+			args++;
 		if (verity_fec_is_enabled(v))
 			args += DM_VERITY_OPTS_FEC;
 		if (v->zero_digest)
@@ -834,6 +860,19 @@ static void verity_status(struct dm_target *ti, status_type_t type,
 				BUG();
 			}
 		}
+		if (v->error_mode != DM_VERITY_MODE_EIO) {
+			DMEMIT(" ");
+			switch (v->error_mode) {
+			case DM_VERITY_MODE_RESTART:
+				DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
+				break;
+			case DM_VERITY_MODE_PANIC:
+				DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
+				break;
+			default:
+				BUG();
+			}
+		}
 		if (v->zero_digest)
 			DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 		if (v->validated_blocks)
@@ -886,6 +925,19 @@ static void verity_status(struct dm_target *ti, status_type_t type,
 				DMEMIT("invalid");
 			}
 		}
+		if (v->error_mode != DM_VERITY_MODE_EIO) {
+			DMEMIT(",verity_error_mode=");
+			switch (v->error_mode) {
+			case DM_VERITY_MODE_RESTART:
+				DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
+				break;
+			case DM_VERITY_MODE_PANIC:
+				DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
+				break;
+			default:
+				DMEMIT("invalid");
+			}
+		}
 		DMEMIT(";");
 		break;
 	}
@@ -1088,6 +1140,25 @@ static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
 	return 0;
 }
 
+static inline bool verity_is_verity_error_mode(const char *arg_name)
+{
+	return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) ||
+		!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC));
+}
+
+static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name)
+{
+	if (v->error_mode)
+		return -EINVAL;
+
+	if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART))
+		v->error_mode = DM_VERITY_MODE_RESTART;
+	else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC))
+		v->error_mode = DM_VERITY_MODE_PANIC;
+
+	return 0;
+}
+
 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
 				 struct dm_verity_sig_opts *verify_args,
 				 bool only_modifier_opts)
@@ -1122,6 +1193,16 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
 			}
 			continue;
 
+		} else if (verity_is_verity_error_mode(arg_name)) {
+			if (only_modifier_opts)
+				continue;
+			r = verity_parse_verity_error_mode(v, arg_name);
+			if (r) {
+				ti->error = "Conflicting error handling parameters";
+				return r;
+			}
+			continue;
+
 		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
 			if (only_modifier_opts)
 				continue;

drivers/md/dm-verity.h

@@ -64,6 +64,7 @@ struct dm_verity {
 	unsigned int digest_size;	/* digest size for the current hash algorithm */
 	unsigned int hash_reqsize; /* the size of temporary space for crypto */
 	enum verity_mode mode;	/* mode for handling verification errors */
+	enum verity_mode error_mode;/* mode for handling I/O errors */
 	unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
 
 	struct workqueue_struct *verify_wq;