From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Henry Cai , NeilBrown Subject: [PATCH 3.18 083/150] md/raid5: fetch_block must fetch all the blocks handle_stripe_dirtying wants. Date: Tue, 13 Jan 2015 23:22:34 -0800 Message-Id: <20150114072059.609658645@linuxfoundation.org> In-Reply-To: <20150114072055.842408181@linuxfoundation.org> References: <20150114072055.842408181@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit 108cef3aa41669610e1836fe638812dd067d72de upstream. It is critical that fetch_block() and handle_stripe_dirtying() are consistent in their analysis of what needs to be loaded. Otherwise raid5 can wait forever for a block that won't be loaded. Currently when writing to a RAID5 that is resyncing, to a location beyond the resync offset, handle_stripe_dirtying chooses a reconstruct-write cycle, but fetch_block() assumes a read-modify-write, and a lockup can happen. So treat that case just like RAID6, just as we do in handle_stripe_dirtying. RAID6 always does reconstruct-write. This bug was introduced when the behaviour of handle_stripe_dirtying was changed in 3.7, so the patch is suitable for any kernel since, though it will need careful merging for some versions. Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f Reported-by: Henry Cai Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman --- drivers/md/raid5.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2917,8 +2917,11 @@ static int fetch_block(struct stripe_hea (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite && (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) && !test_bit(R5_OVERWRITE, &fdev[0]->flags)) || - (sh->raid_conf->level == 6 && s->failed && s->to_write && - s->to_write - s->non_overwrite < sh->raid_conf->raid_disks - 2 && + ((sh->raid_conf->level == 6 || + sh->sector >= sh->raid_conf->mddev->recovery_cp) + && s->failed && s->to_write && + (s->to_write - s->non_overwrite < + sh->raid_conf->raid_disks - sh->raid_conf->max_degraded) && (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))))) { /* we would like to get this block, possibly by computing it, * otherwise read it if the backing disk is insync