BIO_TRACE_COMPLETION
if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
if (bio_flagged(bio, BIO_TRACE_COMPLETION))
bio_set_flag(split, BIO_TRACE_COMPLETION);
if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
bio_set_flag(bio, BIO_TRACE_COMPLETION);
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
bio_clear_flag(bio, BIO_TRACE_COMPLETION);