Commit 7d9f8468 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Data update path won't accidentaly grow replicas 



Previously, there was a bug where if an extent had greater durability
than required (because we needed to move a durability=1 pointer and
ended up putting it on a durability 2 device), we would submit a write
for replicas=2 - the durability of the pointer being rewritten - instead
of the number of replicas required to bring it back up to the
data_replicas option.

This, plus the allocation path sometimes allocating on a greater
durability device than requested, meant that extents could continue
having more and more replicas added as they were being rewritten.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 0af8a06a

fs/bcachefs/data_update.c

+82 −10
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ void bch2_data_update_exit(struct data_update *update) 
	bch2_bio_free_pages_pool(c, &update->op.wbio.bio);

}



void bch2_update_unwritten_extent(struct btree_trans *trans,

static void bch2_update_unwritten_extent(struct btree_trans *trans,

				  struct data_update *update)

{

	struct bch_fs *c = update->op.c;
@@ -436,7 +436,51 @@ void bch2_update_unwritten_extent(struct btree_trans *trans, 
	}

}



int bch2_extent_drop_ptrs(struct btree_trans *trans,

			  struct btree_iter *iter,

			  struct bkey_s_c k,

			  struct data_update_opts data_opts)

{

	struct bch_fs *c = trans->c;

	struct bkey_i *n;

	int ret;



	n = bch2_bkey_make_mut_noupdate(trans, k);

	ret = PTR_ERR_OR_ZERO(n);

	if (ret)

		return ret;



	while (data_opts.kill_ptrs) {

		unsigned i = 0, drop = __fls(data_opts.kill_ptrs);

		struct bch_extent_ptr *ptr;



		bch2_bkey_drop_ptrs(bkey_i_to_s(n), ptr, i++ == drop);

		data_opts.kill_ptrs ^= 1U << drop;

	}



	/*

	 * If the new extent no longer has any pointers, bch2_extent_normalize()

	 * will do the appropriate thing with it (turning it into a

	 * KEY_TYPE_error key, or just a discard if it was a cached extent)

	 */

	bch2_extent_normalize(c, bkey_i_to_s(n));



	/*

	 * Since we're not inserting through an extent iterator

	 * (BTREE_ITER_ALL_SNAPSHOTS iterators aren't extent iterators),

	 * we aren't using the extent overwrite path to delete, we're

	 * just using the normal key deletion path:

	 */

	if (bkey_deleted(&n->k))

		n->k.size = 0;



	return bch2_trans_relock(trans) ?:

		bch2_trans_update(trans, iter, n, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:

		bch2_trans_commit(trans, NULL, NULL, BTREE_INSERT_NOFAIL);

}



int bch2_data_update_init(struct btree_trans *trans,

			  struct btree_iter *iter,

			  struct moving_context *ctxt,

			  struct data_update *m,

			  struct write_point_specifier wp,
@@ -452,7 +496,7 @@ int bch2_data_update_init(struct btree_trans *trans, 
	const struct bch_extent_ptr *ptr;

	unsigned i, reserve_sectors = k.k->size * data_opts.extra_replicas;

	unsigned ptrs_locked = 0;

	int ret;

	int ret = 0;



	bch2_bkey_buf_init(&m->k);

	bch2_bkey_buf_reassemble(&m->k, c, k);
@@ -478,6 +522,8 @@ int bch2_data_update_init(struct btree_trans *trans, 
	bkey_for_each_ptr(ptrs, ptr)

		percpu_ref_get(&bch_dev_bkey_exists(c, ptr->dev)->ref);



	unsigned durability_have = 0, durability_removing = 0;



	i = 0;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {

		bool locked;
@@ -489,8 +535,11 @@ int bch2_data_update_init(struct btree_trans *trans, 
				reserve_sectors += k.k->size;



			m->op.nr_replicas += bch2_extent_ptr_desired_durability(c, &p);

		} else if (!p.ptr.cached) {

			durability_removing += bch2_extent_ptr_desired_durability(c, &p);

		} else if (!p.ptr.cached &&

			   !((1U << i) & m->data_opts.kill_ptrs)) {

			bch2_dev_list_add_dev(&m->op.devs_have, p.ptr.dev);

			durability_have += bch2_extent_ptr_durability(c, &p);

		}



		/*
@@ -529,6 +578,29 @@ int bch2_data_update_init(struct btree_trans *trans, 
		i++;

	}



	/*

	 * If current extent durability is less than io_opts.data_replicas,

	 * we're not trying to rereplicate the extent up to data_replicas here -

	 * unless extra_replicas was specified

	 *

	 * Increasing replication is an explicit operation triggered by

	 * rereplicate, currently, so that users don't get an unexpected -ENOSPC

	 */

	if (durability_have >= io_opts.data_replicas) {

		m->data_opts.kill_ptrs |= m->data_opts.rewrite_ptrs;

		m->data_opts.rewrite_ptrs = 0;

		/* if iter == NULL, it's just a promote */

		if (iter)

			ret = bch2_extent_drop_ptrs(trans, iter, k, data_opts);

		goto done;

	}



	m->op.nr_replicas = min(durability_removing, io_opts.data_replicas - durability_have) +

		m->data_opts.extra_replicas;

	m->op.nr_replicas_required = m->op.nr_replicas;



	BUG_ON(!m->op.nr_replicas);



	if (reserve_sectors) {

		ret = bch2_disk_reservation_add(c, &m->op.res, reserve_sectors,

				m->data_opts.extra_replicas
@@ -538,14 +610,11 @@ int bch2_data_update_init(struct btree_trans *trans, 
			goto err;

	}



	m->op.nr_replicas += m->data_opts.extra_replicas;

	m->op.nr_replicas_required = m->op.nr_replicas;



	BUG_ON(!m->op.nr_replicas);

	if (bkey_extent_is_unwritten(k)) {

		bch2_update_unwritten_extent(trans, m);

		goto done;

	}



	/* Special handling required: */

	if (bkey_extent_is_unwritten(k))

		return -BCH_ERR_unwritten_extent_update;

	return 0;

err:

	i = 0;
@@ -560,6 +629,9 @@ int bch2_data_update_init(struct btree_trans *trans, 
	bch2_bkey_buf_exit(&m->k, c);

	bch2_bio_free_pages_pool(c, &m->op.wbio.bio);

	return ret;

done:

	bch2_data_update_exit(m);

	return ret ?: -BCH_ERR_data_update_done;

}



void bch2_data_update_opts_normalize(struct bkey_s_c k, struct data_update_opts *opts)

fs/bcachefs/data_update.h

+7 −2
Original line number Diff line number Diff line
@@ -32,9 +32,14 @@ int bch2_data_update_index_update(struct bch_write_op *); 
void bch2_data_update_read_done(struct data_update *,

				struct bch_extent_crc_unpacked);



int bch2_extent_drop_ptrs(struct btree_trans *,

			  struct btree_iter *,

			  struct bkey_s_c,

			  struct data_update_opts);



void bch2_data_update_exit(struct data_update *);

void bch2_update_unwritten_extent(struct btree_trans *, struct data_update *);

int bch2_data_update_init(struct btree_trans *, struct moving_context *,

int bch2_data_update_init(struct btree_trans *, struct btree_iter *,

			  struct moving_context *,

			  struct data_update *,

			  struct write_point_specifier,

			  struct bch_io_opts, struct data_update_opts,

fs/bcachefs/errcode.h

+1 −1
Original line number Diff line number Diff line
@@ -162,7 +162,7 @@ 
	x(BCH_ERR_fsck,			fsck_repair_unimplemented)		\

	x(BCH_ERR_fsck,			fsck_repair_impossible)			\

	x(0,				restart_recovery)			\

	x(0,				unwritten_extent_update)		\

	x(0,				data_update_done)			\

	x(EINVAL,			device_state_not_allowed)		\

	x(EINVAL,			member_info_missing)			\

	x(EINVAL,			mismatched_block_size)			\

fs/bcachefs/io_read.c

+1 −1
Original line number Diff line number Diff line
@@ -209,7 +209,7 @@ static struct promote_op *__promote_alloc(struct btree_trans *trans, 
	bio = &op->write.op.wbio.bio;

	bio_init(bio, NULL, bio->bi_inline_vecs, pages, 0);



	ret = bch2_data_update_init(trans, NULL, &op->write,

	ret = bch2_data_update_init(trans, NULL, NULL, &op->write,

			writepoint_hashed((unsigned long) current),

			opts,

			(struct data_update_opts) {

fs/bcachefs/move.c

+5 −53
Original line number Diff line number Diff line
@@ -229,49 +229,6 @@ void bch2_move_stats_init(struct bch_move_stats *stats, char *name) 
	scnprintf(stats->name, sizeof(stats->name), "%s", name);

}



static int bch2_extent_drop_ptrs(struct btree_trans *trans,

				 struct btree_iter *iter,

				 struct bkey_s_c k,

				 struct data_update_opts data_opts)

{

	struct bch_fs *c = trans->c;

	struct bkey_i *n;

	int ret;



	n = bch2_bkey_make_mut_noupdate(trans, k);

	ret = PTR_ERR_OR_ZERO(n);

	if (ret)

		return ret;



	while (data_opts.kill_ptrs) {

		unsigned i = 0, drop = __fls(data_opts.kill_ptrs);

		struct bch_extent_ptr *ptr;



		bch2_bkey_drop_ptrs(bkey_i_to_s(n), ptr, i++ == drop);

		data_opts.kill_ptrs ^= 1U << drop;

	}



	/*

	 * If the new extent no longer has any pointers, bch2_extent_normalize()

	 * will do the appropriate thing with it (turning it into a

	 * KEY_TYPE_error key, or just a discard if it was a cached extent)

	 */

	bch2_extent_normalize(c, bkey_i_to_s(n));



	/*

	 * Since we're not inserting through an extent iterator

	 * (BTREE_ITER_ALL_SNAPSHOTS iterators aren't extent iterators),

	 * we aren't using the extent overwrite path to delete, we're

	 * just using the normal key deletion path:

	 */

	if (bkey_deleted(&n->k))

		n->k.size = 0;



	return bch2_trans_relock(trans) ?:

		bch2_trans_update(trans, iter, n, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:

		bch2_trans_commit(trans, NULL, NULL, BTREE_INSERT_NOFAIL);

}



int bch2_move_extent(struct moving_context *ctxt,

		     struct move_bucket_in_flight *bucket_in_flight,

		     struct btree_iter *iter,
@@ -341,19 +298,11 @@ int bch2_move_extent(struct moving_context *ctxt, 
	io->rbio.bio.bi_iter.bi_sector	= bkey_start_offset(k.k);

	io->rbio.bio.bi_end_io		= move_read_endio;



	ret = bch2_data_update_init(trans, ctxt, &io->write, ctxt->wp,

	ret = bch2_data_update_init(trans, iter, ctxt, &io->write, ctxt->wp,

				    io_opts, data_opts, iter->btree_id, k);

	if (ret && ret != -BCH_ERR_unwritten_extent_update)

	if (ret)

		goto err_free_pages;



	if (ret == -BCH_ERR_unwritten_extent_update) {

		bch2_update_unwritten_extent(trans, &io->write);

		move_free(io);

		return 0;

	}



	BUG_ON(ret);



	io->write.op.end_io = move_write_done;



	if (ctxt->rate)
@@ -397,6 +346,9 @@ int bch2_move_extent(struct moving_context *ctxt, 
err_free:

	kfree(io);

err:

	if (ret == -BCH_ERR_data_update_done)

		return 0;



	this_cpu_inc(c->counters[BCH_COUNTER_move_extent_alloc_mem_fail]);

	trace_move_extent_alloc_mem_fail2(c, k);

	return ret;