From 1c8841c9b7d27da058c62da21c189f4bad4edac2 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Sun, 27 Nov 2016 19:32:32 +0300 Subject: [PATCH] md/raid5: limit request size according to implementation limits 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 Cc: Shaohua Li Cc: Neil Brown Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- drivers/md/raid5.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 10ce885445f6..7af976934441 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6980,6 +6980,15 @@ 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 -- 2.11.0