Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e8d7c332 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Shaohua Li
Browse files

md/raid5: limit request size according to implementation limits 



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: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Shaohua Li <shli@kernel.org>
Cc: Neil Brown <neilb@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 1a0ec5c3

drivers/md/raid5.c

+9 −0
Original line number Diff line number Diff line
@@ -7108,6 +7108,15 @@ 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