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Commit ce7d363a authored by NeilBrown's avatar NeilBrown
Browse files

md/raid5: schedule_construction should abort if nothing to do. 



Since commit 1ed850f3
    md/raid5: make sure to_read and to_write never go negative.

It has been possible for handle_stripe_dirtying to be called
when there isn't actually any work to do.
It then calls schedule_reconstruction() which will set R5_LOCKED
on the parity block(s) even when nothing else is happening.
This then causes problems in do_release_stripe().

So add checks to schedule_reconstruction() so that if it doesn't
find anything to do, it just aborts.

This bug was introduced in v3.7, so the patch is suitable
for -stable kernels since then.

Cc: stable@vger.kernel.org (v3.7+)
Reported-by: default avatarmajianpeng <majianpeng@gmail.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent f3378b48

drivers/md/raid5.c

+22 −16
Original line number Diff line number Diff line
@@ -2283,17 +2283,6 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s, 
	int level = conf->level;



	if (rcw) {

		/* if we are not expanding this is a proper write request, and

		 * there will be bios with new data to be drained into the

		 * stripe cache

		 */

		if (!expand) {

			sh->reconstruct_state = reconstruct_state_drain_run;

			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);

		} else

			sh->reconstruct_state = reconstruct_state_run;



		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);



		for (i = disks; i--; ) {

			struct r5dev *dev = &sh->dev[i];
@@ -2306,6 +2295,21 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s, 
				s->locked++;

			}

		}

		/* if we are not expanding this is a proper write request, and

		 * there will be bios with new data to be drained into the

		 * stripe cache

		 */

		if (!expand) {

			if (!s->locked)

				/* False alarm, nothing to do */

				return;

			sh->reconstruct_state = reconstruct_state_drain_run;

			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);

		} else

			sh->reconstruct_state = reconstruct_state_run;



		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);



		if (s->locked + conf->max_degraded == disks)

			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))

				atomic_inc(&conf->pending_full_writes);
@@ -2314,11 +2318,6 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s, 
		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||

			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));



		sh->reconstruct_state = reconstruct_state_prexor_drain_run;

		set_bit(STRIPE_OP_PREXOR, &s->ops_request);

		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);

		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);



		for (i = disks; i--; ) {

			struct r5dev *dev = &sh->dev[i];

			if (i == pd_idx)
@@ -2333,6 +2332,13 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s, 
				s->locked++;

			}

		}

		if (!s->locked)

			/* False alarm - nothing to do */

			return;

		sh->reconstruct_state = reconstruct_state_prexor_drain_run;

		set_bit(STRIPE_OP_PREXOR, &s->ops_request);

		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);

		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);

	}



	/* keep the parity disk(s) locked while asynchronous operations