Commit cb6055e6 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Handle race between stripe reuse, invalidate_stripe_to_dev 



When creating a new stripe, we may reuse an existing stripe that has
some empty and some nonempty blocks.

Generally, the existing stripe won't change underneath us - except for
block sector counts, which we copy to the new key in
ec_stripe_key_update.

But the device removal path can now invalidate stripe pointers to a
device, and that can race with stripe reuse.

Change ec_stripe_key_update() to check for and resolve this
inconsistency.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent b1e56226

fs/bcachefs/ec.c

+45 −28
Original line number Diff line number Diff line
@@ -1206,47 +1206,62 @@ void bch2_do_stripe_deletes(struct bch_fs *c) 
/* stripe creation: */



static int ec_stripe_key_update(struct btree_trans *trans,

				struct bkey_i_stripe *new,

				bool create)

				struct bkey_i_stripe *old,

				struct bkey_i_stripe *new)

{

	struct bch_fs *c = trans->c;

	struct btree_iter iter;

	struct bkey_s_c k;

	int ret;

	bool create = !old;



	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,

	struct btree_iter iter;

	struct bkey_s_c k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,

					       new->k.p, BTREE_ITER_intent);

	ret = bkey_err(k);

	int ret = bkey_err(k);

	if (ret)

		goto err;



	if (k.k->type != (create ? KEY_TYPE_deleted : KEY_TYPE_stripe)) {

		bch2_fs_inconsistent(c, "error %s stripe: got existing key type %s",

	if (bch2_fs_inconsistent_on(k.k->type != (create ? KEY_TYPE_deleted : KEY_TYPE_stripe),

				    c, "error %s stripe: got existing key type %s",

				    create ? "creating" : "updating",

				     bch2_bkey_types[k.k->type]);

				    bch2_bkey_types[k.k->type])) {

		ret = -EINVAL;

		goto err;

	}



	if (k.k->type == KEY_TYPE_stripe) {

		const struct bch_stripe *old = bkey_s_c_to_stripe(k).v;

		unsigned i;

		const struct bch_stripe *v = bkey_s_c_to_stripe(k).v;



		BUG_ON(old->v.nr_blocks != new->v.nr_blocks);

		BUG_ON(old->v.nr_blocks != v->nr_blocks);



		for (unsigned i = 0; i < new->v.nr_blocks; i++) {

			unsigned sectors = stripe_blockcount_get(v, i);



		if (old->nr_blocks != new->v.nr_blocks) {

			bch_err(c, "error updating stripe: nr_blocks does not match");

			if (!bch2_extent_ptr_eq(old->v.ptrs[i], new->v.ptrs[i]) && sectors) {

				struct printbuf buf = PRINTBUF;



				prt_printf(&buf, "stripe changed nonempty block %u", i);

				prt_str(&buf, "\nold: ");

				bch2_bkey_val_to_text(&buf, c, k);

				prt_str(&buf, "\nnew: ");

				bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&new->k_i));

				bch2_fs_inconsistent(c, "%s", buf.buf);

				printbuf_exit(&buf);

				ret = -EINVAL;

				goto err;

			}



		for (i = 0; i < new->v.nr_blocks; i++) {

			unsigned v = stripe_blockcount_get(old, i);

			/*

			 * If the stripe ptr changed underneath us, it must have

			 * been dev_remove_stripes() -> * invalidate_stripe_to_dev()

			 */

			if (!bch2_extent_ptr_eq(old->v.ptrs[i], v->ptrs[i])) {

				BUG_ON(v->ptrs[i].dev != BCH_SB_MEMBER_INVALID);



			BUG_ON(v &&

			       (old->ptrs[i].dev != new->v.ptrs[i].dev ||

				old->ptrs[i].gen != new->v.ptrs[i].gen ||

				old->ptrs[i].offset != new->v.ptrs[i].offset));

				if (bch2_extent_ptr_eq(old->v.ptrs[i], new->v.ptrs[i]))

					new->v.ptrs[i].dev = BCH_SB_MEMBER_INVALID;

			}



			stripe_blockcount_set(&new->v, i, v);

			stripe_blockcount_set(&new->v, i, sectors);

		}

	}
@@ -1508,8 +1523,10 @@ static void ec_stripe_create(struct ec_stripe_new *s) 
			    BCH_TRANS_COMMIT_no_check_rw|

			    BCH_TRANS_COMMIT_no_enospc,

			    ec_stripe_key_update(trans,

					bkey_i_to_stripe(&s->new_stripe.key),

					!s->have_existing_stripe));

					s->have_existing_stripe

					? bkey_i_to_stripe(&s->existing_stripe.key)

					: NULL,

					bkey_i_to_stripe(&s->new_stripe.key)));

	bch_err_msg(c, ret, "creating stripe key");

	if (ret) {

		goto err;

fs/bcachefs/extents.h

+10 −0
Original line number Diff line number Diff line
@@ -695,6 +695,16 @@ void bch2_bkey_ptrs_to_text(struct printbuf *, struct bch_fs *, 
int bch2_bkey_ptrs_validate(struct bch_fs *, struct bkey_s_c,

			    enum bch_validate_flags);



static inline bool bch2_extent_ptr_eq(struct bch_extent_ptr ptr1,

				      struct bch_extent_ptr ptr2)

{

	return (ptr1.cached	== ptr2.cached &&

		ptr1.unwritten	== ptr2.unwritten &&

		ptr1.offset	== ptr2.offset &&

		ptr1.dev	== ptr2.dev &&

		ptr1.dev	== ptr2.dev);

}



void bch2_ptr_swab(struct bkey_s);



const struct bch_extent_rebalance *bch2_bkey_rebalance_opts(struct bkey_s_c);