Report dnodes with faulty bonuslen

In files created/modified before 4254acb there may be a corruption of
xattrs which is not reported during scrub and normal send/receive. It
manifests only as an error when raw sending/receiving. This happens
because currently only the raw receive path checks for discrepancies
between the dnode bonus length and the spill pointer flag.

In case we encounter a dnode whose bonus length is greater than the
predicted one, we should report an error. Modify in this regard
dnode_sync() with an assertion at the end, dump_dnode() to error out,
dsl_scan_recurse() to report errors during a scrub, and zstream to
report a warning when dumping. Also added a test to verify spill blocks
are sent correctly in a raw send.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #12720 
Closes #13014

cmd/zstream/zstream_dump.c

@@ -461,6 +461,14 @@ zstream_do_dump(int argc, char *argv[])
 				    BSWAP_64(drro->drr_maxblkid);
 			}
 
+			if (drro->drr_bonuslen > drro->drr_raw_bonuslen) {
+				(void) fprintf(stderr,
+				    "Warning: Object %llu has bonuslen = "
+				    "%u > raw_bonuslen = %u\n\n",
+				    (u_longlong_t)drro->drr_object,
+				    drro->drr_bonuslen, drro->drr_raw_bonuslen);
+			}
+
 			payload_size = DRR_OBJECT_PAYLOAD_SIZE(drro);
 
 			if (verbose) {