block/blk-iolatency: account per-cpu latency stats over possible CPUs

iolatency_check_latencies() and iolatency_ssd_stat() iterate a blkg's
per-cpu latency stats with for_each_online_cpu().  When a CPU that has
accumulated io.latency samples goes offline, its bucket is skipped: the
check loop (which also resets) neither sums nor clears it, and the show
path under-reports.  On re-online the stranded samples are flushed into
a later check window, which can trigger a spurious throttle/scale
adjustment.

Fixes: d70675121546 ("block: introduce blk-iolatency io controller")
Fixes: 1fa2840e56f9 ("blk-iolatency: use a percentile approache for ssd's")
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Yu Kuai <yukuai@fygo.io>
Link: https://patch.msgid.link/20260720093726.28965-3-cui.tao@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions