• Omar Sandoval's avatar
    sbitmap: re-initialize allocation hints after resize · 05fd095d
    Omar Sandoval authored
    After a struct sbitmap_queue is resized smaller, the allocation hints
    may still be set to bits beyond the new depth of the bitmap. This means
    that, for example, if the number of blk-mq tags is reduced through
    sysfs, more requests than the nominal queue depth may be in flight.
    It's tempting to fix this at resize time by doing a one-time
    reinitialization of the hints, but this can race with
    __sbitmap_queue_get() updating the hint. Instead, check the hint before
    we use it. This caused no measurable performance difference in my
    synthetic benchmarks.
    Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
    Signed-off-by: default avatarJens Axboe <axboe@fb.com>