Commit 82af5ceb authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Refactor delete_dead_snapshots() 



Consolidate per-key work into delete_dead_snapshots_process_key(), so we
now walk all keys once, not twice.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 218e5e0c

fs/bcachefs/snapshot.c

+25 −40
Original line number Diff line number Diff line
@@ -1351,7 +1351,7 @@ int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent, 
 * that key to snapshot leaf nodes, where we can mutate it

 */



static int snapshot_delete_key(struct btree_trans *trans,

static int delete_dead_snapshots_process_key(struct btree_trans *trans,

			       struct btree_iter *iter,

			       struct bkey_s_c k,

			       snapshot_id_list *deleted,
@@ -1360,26 +1360,26 @@ static int snapshot_delete_key(struct btree_trans *trans, 
{

	struct bch_fs *c = trans->c;

	u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);

	if (!equiv) /* key for invalid snapshot node, but we chose not to delete */

		return 0;



	if (!bkey_eq(k.k->p, *last_pos))

		equiv_seen->nr = 0;

	*last_pos = k.k->p;



	if (snapshot_list_has_id(deleted, k.k->p.snapshot) ||

	    snapshot_list_has_id(equiv_seen, equiv)) {

	if (snapshot_list_has_id(deleted, k.k->p.snapshot))

		return bch2_btree_delete_at(trans, iter,

					    BTREE_UPDATE_internal_snapshot_node);

	} else {

		return snapshot_list_add(c, equiv_seen, equiv);

	}

}



static int move_key_to_correct_snapshot(struct btree_trans *trans,

			       struct btree_iter *iter,

			       struct bkey_s_c k)

{

	struct bch_fs *c = trans->c;

	u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);

	if (!bpos_eq(*last_pos, k.k->p) &&

	    snapshot_list_has_id(equiv_seen, equiv))

		return bch2_btree_delete_at(trans, iter,

					    BTREE_UPDATE_internal_snapshot_node);



	*last_pos = k.k->p;



	int ret = snapshot_list_add_nodup(c, equiv_seen, equiv);

	if (ret)

		return ret;



	/*

	 * When we have a linear chain of snapshot nodes, we consider
@@ -1389,21 +1389,20 @@ static int move_key_to_correct_snapshot(struct btree_trans *trans, 
	 *

	 * If there are multiple keys in different snapshots at the same

	 * position, we're only going to keep the one in the newest

	 * snapshot - the rest have been overwritten and are redundant,

	 * and for the key we're going to keep we need to move it to the

	 * equivalance class ID if it's not there already.

	 * snapshot (we delete the others above) - the rest have been

	 * overwritten and are redundant, and for the key we're going to keep we

	 * need to move it to the equivalance class ID if it's not there

	 * already.

	 */

	if (equiv != k.k->p.snapshot) {

		struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);

		struct btree_iter new_iter;

		int ret;



		ret = PTR_ERR_OR_ZERO(new);

		int ret = PTR_ERR_OR_ZERO(new);

		if (ret)

			return ret;



		new->k.p.snapshot = equiv;



		struct btree_iter new_iter;

		bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p,

				     BTREE_ITER_all_snapshots|

				     BTREE_ITER_cached|
@@ -1538,7 +1537,6 @@ int bch2_delete_dead_snapshots(struct bch_fs *c) 
	struct btree_trans *trans;

	snapshot_id_list deleted = { 0 };

	snapshot_id_list deleted_interior = { 0 };

	u32 id;

	int ret = 0;



	if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags))
@@ -1585,33 +1583,20 @@ int bch2_delete_dead_snapshots(struct bch_fs *c) 
	if (ret)

		goto err;



	for (id = 0; id < BTREE_ID_NR; id++) {

	for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {

		struct bpos last_pos = POS_MIN;

		snapshot_id_list equiv_seen = { 0 };

		struct disk_reservation res = { 0 };



		if (!btree_type_has_snapshots(id))

			continue;



		/*

		 * deleted inodes btree is maintained by a trigger on the inodes

		 * btree - no work for us to do here, and it's not safe to scan

		 * it because we'll see out of date keys due to the btree write

		 * buffer:

		 */

		if (id == BTREE_ID_deleted_inodes)

		if (!btree_type_has_snapshots(btree))

			continue;



		ret = for_each_btree_key_commit(trans, iter,

				id, POS_MIN,

				BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,

				&res, NULL, BCH_TRANS_COMMIT_no_enospc,

			snapshot_delete_key(trans, &iter, k, &deleted, &equiv_seen, &last_pos)) ?:

		      for_each_btree_key_commit(trans, iter,

				id, POS_MIN,

				btree, POS_MIN,

				BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,

				&res, NULL, BCH_TRANS_COMMIT_no_enospc,

			move_key_to_correct_snapshot(trans, &iter, k));

			delete_dead_snapshots_process_key(trans, &iter, k, &deleted,

							  &equiv_seen, &last_pos));



		bch2_disk_reservation_put(c, &res);

		darray_exit(&equiv_seen);