| From | Willy Tarreau <> | Subject | [PATCH 3.10 018/268] md/raid5: limit request size according to implementation limits | Date | Mon, 19 Jun 2017 20:28:37 +0200 |
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From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
commit e8d7c33232e5fdfa761c3416539bc5b4acd12db5 upstream.
Current implementation employ 16bit counter of active stripes in lower bits of bio->bi_phys_segments. If request is big enough to overflow this counter bio will be completed and freed too early.
Fortunately this not happens in default configuration because several other limits prevent that: stripe_cache_size * nr_disks effectively limits count of active stripes. And small max_sectors_kb at lower disks prevent that during normal read/write operations.
Overflow easily happens in discard if it's enabled by module parameter "devices_handle_discard_safely" and stripe_cache_size is set big enough.
This patch limits requests size with 256Mb - 8Kb to prevent overflows.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Shaohua Li <shli@kernel.org> Cc: Neil Brown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Willy Tarreau <w@1wt.eu> --- drivers/md/raid5.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 9ee3c46..8f5c890 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5616,6 +5616,15 @@ static int run(struct mddev *mddev) stripe = (stripe | (stripe-1)) + 1; mddev->queue->limits.discard_alignment = stripe; mddev->queue->limits.discard_granularity = stripe; + + /* + * We use 16-bit counter of active stripes in bi_phys_segments + * (minus one for over-loaded initialization) + */ + blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS); + blk_queue_max_discard_sectors(mddev->queue, + 0xfffe * STRIPE_SECTORS); + /* * unaligned part of discard request will be ignored, so can't * guarantee discard_zeroes_data -- 2.8.0.rc2.1.gbe9624a
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