From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Khlebnikov Subject: [PATCH] md/raid5: limit request size according to implementation limits Date: Sun, 27 Nov 2016 19:32:32 +0300 Message-ID: <148026435214.19980.7956943898609877817.stgit@buzz> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Shaohua Li , Neil Brown Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org List-Id: linux-raid.ids 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 Cc: stable@vger.kernel.org --- drivers/md/raid5.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 92ac251e91e6..cce6057b9aca 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6984,6 +6984,15 @@ static int raid5_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