Commits
Shaohua Li committed 6ab2a4b806a
RAID5: revert e9e4c377e2f563 to fix a livelock Revert commit e9e4c377e2f563(md/raid5: per hash value and exclusive wait_for_stripe) The problem is raid5_get_active_stripe waits on conf->wait_for_stripe[hash]. Assume hash is 0. My test release stripes in this order: - release all stripes with hash 0 - raid5_get_active_stripe still sleeps since active_stripes > max_nr_stripes * 3 / 4 - release all stripes with hash other than 0. active_stripes becomes 0 - raid5_get_active_stripe still sleeps, since nobody wakes up wait_for_stripe[0] The system live locks. The problem is active_stripes isn't a per-hash count. Revert the patch makes the live lock go away. Cc: stable@vger.kernel.org (v4.2+) Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com> Cc: NeilBrown <neilb@suse.de> Signed-off-by: Shaohua Li <shli@fb.com>