add: int curr_is_seq;
context: static int sshfs_async_read(struct sshfs_file *sf, char *rbuf, size_t size,                            off_t offset){    int res = 0;    size_t total = 0;    struct read_chunk *chunk;    struct read_chunk *chunk_prev = NULL;    size_t origsize = size;            pthread_mutex_lock(&lock);    chunk = search_read_chunk(sf, offset);    pthread_mutex_unlock(&lock);    if (chunk && chunk->size < size) {        chunk_prev = chunk;        size -= chunk->size;        offset += chunk->size;        chunk = NULL;    }    if (!chunk)        res = submit_read(sf, size, offset, &chunk);    if (chunk && chunk->size <= size)        submit_read(sf, origsize, offset + size, &sf->readahead);    if (chunk_prev) {        size_t prev_size = chunk_prev->size;        res = wait_chunk(chunk_prev, rbuf, prev_size);        if (res < (int) prev_size) {            chunk_put_locked(chunk);            return res;        }        rbuf += res;        total += res;    }    res = wait_chunk(chunk, rbuf, size);    if (res > 0)        total += res;    if (res < 0)        return res;    return total;}