bcachefs: Copygc now uses backpointers

Previously, copygc needed to walk the entire extents & reflink btrees to
find extents that needed to be moved.

Now that we have backpointers, this patch implements
bch2_evacuate_bucket() in the move code, which copygc now uses for
evacuating mostly empty buckets.

Also, thanks to the new backpointers code, copygc can now move btree
nodes.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

4 files changed, 272 insertions, 263 deletions

diff --git a/fs/bcachefs/buckets_types.h b/fs/bcachefs/buckets_types.h
index 0a9dd5af3524..1dbba7d906dd 100644
--- a/fs/bcachefs/buckets_types.h
+++ b/fs/bcachefs/buckets_types.h
@@ -95,7 +95,7 @@ struct copygc_heap_entry {
 	u8			replicas;
 	u32			fragmentation;
 	u32			sectors;
-	u64			offset;
+	u64			bucket;
 };
 
 typedef HEAP(struct copygc_heap_entry) copygc_heap;
diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index a8f6d5a3e1ba..36d20dc8aaf3 100644
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include "bcachefs.h"
+#include "alloc_background.h"
 #include "alloc_foreground.h"
+#include "backpointers.h"
 #include "bkey_buf.h"
 #include "btree_gc.h"
 #include "btree_update.h"
@@ -9,6 +11,7 @@
 #include "buckets.h"
 #include "disk_groups.h"
 #include "ec.h"
+#include "error.h"
 #include "inode.h"
 #include "io.h"
 #include "journal_reclaim.h"
@@ -632,6 +635,70 @@ err:
 	return ret;
 }
 
+static int move_ratelimit(struct btree_trans *trans,
+			  struct moving_context *ctxt,
+			  struct bch_ratelimit *rate)
+{
+	u64 delay;
+
+	do {
+		delay = rate ? bch2_ratelimit_delay(rate) : 0;
+
+		if (delay) {
+			bch2_trans_unlock(trans);
+			set_current_state(TASK_INTERRUPTIBLE);
+		}
+
+		if ((current->flags & PF_KTHREAD) && kthread_should_stop()) {
+			__set_current_state(TASK_RUNNING);
+			return 1;
+		}
+
+		if (delay)
+			schedule_timeout(delay);
+
+		if (unlikely(freezing(current))) {
+			move_ctxt_wait_event(ctxt, trans, list_empty(&ctxt->reads));
+			try_to_freeze();
+		}
+	} while (delay);
+
+	move_ctxt_wait_event(ctxt, trans,
+		atomic_read(&ctxt->write_sectors) <
+		SECTORS_IN_FLIGHT_PER_DEVICE);
+
+	move_ctxt_wait_event(ctxt, trans,
+		atomic_read(&ctxt->read_sectors) <
+		SECTORS_IN_FLIGHT_PER_DEVICE);
+
+	return 0;
+}
+
+static int move_get_io_opts(struct btree_trans *trans,
+			    struct bch_io_opts *io_opts,
+			    struct bkey_s_c k, u64 *cur_inum)
+{
+	struct bch_inode_unpacked inode;
+	int ret;
+
+	if (*cur_inum == k.k->p.inode)
+		return 0;
+
+	*io_opts = bch2_opts_to_inode_opts(trans->c->opts);
+
+	ret = lookup_inode(trans,
+			   SPOS(0, k.k->p.inode, k.k->p.snapshot),
+			   &inode);
+	if (ret == -EINTR)
+		return ret;
+
+	if (!ret)
+		bch2_io_opts_apply(io_opts, bch2_inode_opts_get(&inode));
+
+	*cur_inum = k.k->p.inode;
+	return 0;
+}
+
 static int __bch2_move_data(struct bch_fs *c,
 		struct moving_context *ctxt,
 		struct bch_ratelimit *rate,
@@ -642,7 +709,6 @@ static int __bch2_move_data(struct bch_fs *c,
 		struct bch_move_stats *stats,
 		enum btree_id btree_id)
 {
-	bool kthread = (current->flags & PF_KTHREAD) != 0;
 	struct bch_io_opts io_opts = bch2_opts_to_inode_opts(c->opts);
 	struct bkey_buf sk;
 	struct btree_trans trans;
@@ -650,7 +716,7 @@ static int __bch2_move_data(struct bch_fs *c,
 	struct bkey_s_c k;
 	struct data_opts data_opts;
 	enum data_cmd data_cmd;
-	u64 delay, cur_inum = U64_MAX;
+	u64 cur_inum = U64_MAX;
 	int ret = 0, ret2;
 
 	bch2_bkey_buf_init(&sk);
@@ -667,37 +733,7 @@ static int __bch2_move_data(struct bch_fs *c,
 	if (rate)
 		bch2_ratelimit_reset(rate);
 
-	while (1) {
-		do {
-			delay = rate ? bch2_ratelimit_delay(rate) : 0;
-
-			if (delay) {
-				bch2_trans_unlock(&trans);
-				set_current_state(TASK_INTERRUPTIBLE);
-			}
-
-			if (kthread && (ret = kthread_should_stop())) {
-				__set_current_state(TASK_RUNNING);
-				goto out;
-			}
-
-			if (delay)
-				schedule_timeout(delay);
-
-			if (unlikely(freezing(current))) {
-				move_ctxt_wait_event(ctxt, &trans, list_empty(&ctxt->reads));
-				try_to_freeze();
-			}
-		} while (delay);
-
-		move_ctxt_wait_event(ctxt, &trans,
-			atomic_read(&ctxt->write_sectors) <
-			SECTORS_IN_FLIGHT_PER_DEVICE);
-
-		move_ctxt_wait_event(ctxt, &trans,
-			atomic_read(&ctxt->read_sectors) <
-			SECTORS_IN_FLIGHT_PER_DEVICE);
-
+	while (!move_ratelimit(&trans, ctxt, rate)) {
 		bch2_trans_begin(&trans);
 
 		k = bch2_btree_iter_peek(&iter);
@@ -718,23 +754,9 @@ static int __bch2_move_data(struct bch_fs *c,
 		if (!bkey_extent_is_direct_data(k.k))
 			goto next_nondata;
 
-		if (btree_id == BTREE_ID_extents &&
-		    cur_inum != k.k->p.inode) {
-			struct bch_inode_unpacked inode;
-
-			io_opts = bch2_opts_to_inode_opts(c->opts);
-
-			ret = lookup_inode(&trans,
-					SPOS(0, k.k->p.inode, k.k->p.snapshot),
-					&inode);
-			if (ret == -EINTR)
-				continue;
-
-			if (!ret)
-				bch2_io_opts_apply(&io_opts, bch2_inode_opts_get(&inode));
-
-			cur_inum = k.k->p.inode;
-		}
+		ret = move_get_io_opts(&trans, &io_opts, k, &cur_inum);
+		if (ret)
+			continue;
 
 		switch ((data_cmd = pred(c, arg, k, &io_opts, &data_opts))) {
 		case DATA_SKIP:
@@ -779,7 +801,6 @@ next:
 next_nondata:
 		bch2_btree_iter_advance(&iter);
 	}
-out:
 
 	bch2_trans_iter_exit(&trans, &iter);
 	bch2_trans_exit(&trans);
@@ -848,7 +869,6 @@ int bch2_move_data(struct bch_fs *c,
 			break;
 	}
 
-
 	move_ctxt_wait_event(&ctxt, NULL, list_empty(&ctxt.reads));
 	closure_sync(&ctxt.cl);
 
@@ -862,6 +882,167 @@ int bch2_move_data(struct bch_fs *c,
 	return ret;
 }
 
+static int verify_bucket_evacuated(struct btree_trans *trans, struct bpos bucket, int gen)
+{
+	struct bch_fs *c = trans->c;
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	int ret;
+
+	bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
+			     bucket, BTREE_ITER_CACHED);
+	k = bch2_btree_iter_peek_slot(&iter);
+	ret = bkey_err(k);
+
+	if (!ret && k.k->type == KEY_TYPE_alloc_v4) {
+		struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
+
+		if (a.v->gen == gen &&
+		    a.v->dirty_sectors) {
+			struct printbuf buf = PRINTBUF;
+
+			prt_str(&buf, "failed to evacuate bucket ");
+			bch2_bkey_val_to_text(&buf, c, k);
+
+			bch_err_ratelimited(c, "%s", buf.buf);
+			printbuf_exit(&buf);
+		}
+	}
+
+	bch2_trans_iter_exit(trans, &iter);
+	return ret;
+}
+
+int bch2_evacuate_bucket(struct bch_fs *c,
+			 struct bpos bucket, int gen,
+			 struct bch_ratelimit *rate,
+			 struct write_point_specifier wp,
+			 enum data_cmd data_cmd,
+			 struct data_opts *data_opts,
+			 struct bch_move_stats *stats)
+{
+	struct bch_io_opts io_opts = bch2_opts_to_inode_opts(c->opts);
+	struct moving_context ctxt = { .stats = stats };
+	struct btree_trans trans;
+	struct btree_iter iter;
+	struct bkey_buf sk;
+	struct bch_backpointer bp;
+	u64 bp_offset = 0, cur_inum = U64_MAX;
+	int ret = 0;
+
+	bch2_bkey_buf_init(&sk);
+	bch2_trans_init(&trans, c, 0, 0);
+	progress_list_add(c, stats);
+	closure_init_stack(&ctxt.cl);
+	INIT_LIST_HEAD(&ctxt.reads);
+	init_waitqueue_head(&ctxt.wait);
+
+	stats->data_type = BCH_DATA_user;
+
+	while (!(ret = move_ratelimit(&trans, &ctxt, rate))) {
+		bch2_trans_begin(&trans);
+
+		ret = bch2_get_next_backpointer(&trans, bucket, gen,
+						&bp_offset, &bp);
+		if (ret == -EINTR)
+			continue;
+		if (ret)
+			goto err;
+		if (bp_offset == U64_MAX)
+			break;
+
+		if (!bp.level) {
+			struct bkey_s_c k;
+
+			k = bch2_backpointer_get_key(&trans, &iter,
+						bucket, bp_offset, bp);
+			ret = bkey_err(k);
+			if (ret == -EINTR)
+				continue;
+			if (ret)
+				goto err;
+			if (!k.k)
+				continue;
+
+			bch2_bkey_buf_reassemble(&sk, c, k);
+			k = bkey_i_to_s_c(sk.k);
+			bch2_trans_iter_exit(&trans, &iter);
+
+			ret = move_get_io_opts(&trans, &io_opts, k, &cur_inum);
+			if (ret)
+				continue;
+
+			data_opts->target	= io_opts.background_target;
+			data_opts->rewrite_dev	= bucket.inode;
+
+			ret = bch2_move_extent(&trans, &ctxt, wp, io_opts, bp.btree_id, k,
+						data_cmd, *data_opts);
+			if (ret == -EINTR)
+				continue;
+			if (ret == -ENOMEM) {
+				/* memory allocation failure, wait for some IO to finish */
+				bch2_move_ctxt_wait_for_io(&ctxt, &trans);
+				continue;
+			}
+			if (ret)
+				goto err;
+
+			if (rate)
+				bch2_ratelimit_increment(rate, k.k->size);
+			atomic64_add(k.k->size, &stats->sectors_seen);
+		} else {
+			struct btree *b;
+
+			b = bch2_backpointer_get_node(&trans, &iter,
+						bucket, bp_offset, bp);
+			ret = PTR_ERR_OR_ZERO(b);
+			if (ret == -EINTR)
+				continue;
+			if (ret)
+				goto err;
+			if (!b)
+				continue;
+
+			ret = bch2_btree_node_rewrite(&trans, &iter, b, 0);
+			bch2_trans_iter_exit(&trans, &iter);
+
+			if (ret == -EINTR)
+				continue;
+			if (ret)
+				goto err;
+
+			if (rate)
+				bch2_ratelimit_increment(rate, c->opts.btree_node_size >> 9);
+			atomic64_add(c->opts.btree_node_size >> 9, &stats->sectors_seen);
+			atomic64_add(c->opts.btree_node_size >> 9, &stats->sectors_moved);
+		}
+
+		bp_offset++;
+	}
+
+	if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG) && gen >= 0) {
+		bch2_trans_unlock(&trans);
+		move_ctxt_wait_event(&ctxt, NULL, list_empty(&ctxt.reads));
+		closure_sync(&ctxt.cl);
+		lockrestart_do(&trans, verify_bucket_evacuated(&trans, bucket, gen));
+	}
+err:
+	bch2_trans_exit(&trans);
+	bch2_bkey_buf_exit(&sk, c);
+
+	move_ctxt_wait_event(&ctxt, NULL, list_empty(&ctxt.reads));
+	closure_sync(&ctxt.cl);
+	progress_list_del(c, stats);
+
+	EBUG_ON(atomic_read(&ctxt.write_sectors));
+
+	trace_move_data(c,
+			atomic64_read(&stats->sectors_moved),
+			atomic64_read(&stats->keys_moved));
+
+	return ret;
+}
+
 typedef enum data_cmd (*move_btree_pred)(struct bch_fs *, void *,
 					 struct btree *, struct bch_io_opts *,
 					 struct data_opts *);
diff --git a/fs/bcachefs/move.h b/fs/bcachefs/move.h
index 2a789a1158ca..c69b6b5abe9e 100644
--- a/fs/bcachefs/move.h
+++ b/fs/bcachefs/move.h
@@ -62,6 +62,12 @@ int bch2_move_data(struct bch_fs *,
 		   move_pred_fn, void *,
 		   struct bch_move_stats *);
 
+int bch2_evacuate_bucket(struct bch_fs *, struct bpos, int,
+			 struct bch_ratelimit *,
+			 struct write_point_specifier,
+			 enum data_cmd,
+			 struct data_opts *,
+			 struct bch_move_stats *);
 int bch2_data_job(struct bch_fs *,
 		  struct bch_move_stats *,
 		  struct bch_ioctl_data);
diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
index 99980c3d5d55..efb09e1c3652 100644
--- a/fs/bcachefs/movinggc.c
+++ b/fs/bcachefs/movinggc.c
@@ -30,80 +30,6 @@
 #include <linux/sort.h>
 #include <linux/wait.h>
 
-static int bucket_offset_cmp(const void *_l, const void *_r, size_t size)
-{
-	const struct copygc_heap_entry *l = _l;
-	const struct copygc_heap_entry *r = _r;
-
-	return  cmp_int(l->dev,    r->dev) ?:
-		cmp_int(l->offset, r->offset);
-}
-
-static enum data_cmd copygc_pred(struct bch_fs *c, void *arg,
-				 struct bkey_s_c k,
-				 struct bch_io_opts *io_opts,
-				 struct data_opts *data_opts)
-{
-	copygc_heap *h = &c->copygc_heap;
-	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-	const union bch_extent_entry *entry;
-	struct extent_ptr_decoded p = { 0 };
-
-	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
-		struct bch_dev *ca = bch_dev_bkey_exists(c, p.ptr.dev);
-		struct copygc_heap_entry search = {
-			.dev	= p.ptr.dev,
-			.offset	= p.ptr.offset,
-		};
-		ssize_t i;
-
-		if (p.ptr.cached)
-			continue;
-
-		i = eytzinger0_find_le(h->data, h->used,
-				       sizeof(h->data[0]),
-				       bucket_offset_cmp, &search);
-#if 0
-		/* eytzinger search verify code: */
-		ssize_t j = -1, k;
-
-		for (k = 0; k < h->used; k++)
-			if (h->data[k].offset <= ptr->offset &&
-			    (j < 0 || h->data[k].offset > h->data[j].offset))
-				j = k;
-
-		BUG_ON(i != j);
-#endif
-		if (i >= 0 &&
-		    p.ptr.dev == h->data[i].dev &&
-		    p.ptr.offset < h->data[i].offset + ca->mi.bucket_size &&
-		    p.ptr.gen == h->data[i].gen) {
-			/*
-			 * We need to use the journal reserve here, because
-			 *  - journal reclaim depends on btree key cache
-			 *    flushing to make forward progress,
-			 *  - which has to make forward progress when the
-			 *    journal is pre-reservation full,
-			 *  - and depends on allocation - meaning allocator and
-			 *    copygc
-			 */
-
-			data_opts->target		= io_opts->background_target;
-			data_opts->nr_replicas		= 1;
-			data_opts->btree_insert_flags	= BTREE_INSERT_USE_RESERVE|
-				JOURNAL_WATERMARK_copygc;
-			data_opts->rewrite_dev		= p.ptr.dev;
-
-			if (p.has_ec)
-				data_opts->nr_replicas += p.ec.redundancy;
-
-			return DATA_REWRITE;
-		}
-	}
-
-	return DATA_SKIP;
-}
-
 static inline int fragmentation_cmp(copygc_heap *heap,
 				   struct copygc_heap_entry l,
 				   struct copygc_heap_entry r)
@@ -111,7 +37,7 @@ static inline int fragmentation_cmp(copygc_heap *heap,
 	return cmp_int(l.fragmentation, r.fragmentation);
 }
 
-static int walk_buckets_to_copygc(struct bch_fs *c)
+static int find_buckets_to_copygc(struct bch_fs *c)
 {
 	copygc_heap *h = &c->copygc_heap;
 	struct btree_trans trans;
@@ -122,6 +48,14 @@ static int walk_buckets_to_copygc(struct bch_fs *c)
 
 	bch2_trans_init(&trans, c, 0, 0);
 
+	/*
+	 * Find buckets with lowest sector counts, skipping completely
+	 * empty buckets, by building a maxheap sorted by sector count,
+	 * and repeatedly replacing the maximum element until all
+	 * buckets have been visited.
+	 */
+	h->used = 0;
+
 	for_each_btree_key(&trans, iter, BTREE_ID_alloc, POS_MIN,
 			   BTREE_ITER_PREFETCH, k, ret) {
 		struct bch_dev *ca = bch_dev_bkey_exists(c, iter.pos.inode);
@@ -129,7 +63,8 @@ static int walk_buckets_to_copygc(struct bch_fs *c)
 
 		bch2_alloc_to_v4(k, &a);
 
-		if (a.data_type != BCH_DATA_user ||
+		if ((a.data_type != BCH_DATA_btree &&
+		     a.data_type != BCH_DATA_user) ||
 		    a.dirty_sectors >= ca->mi.bucket_size ||
 		    bch2_bucket_is_open(c, iter.pos.inode, iter.pos.offset))
 			continue;
@@ -141,7 +76,7 @@ static int walk_buckets_to_copygc(struct bch_fs *c)
 			.fragmentation	= div_u64((u64) a.dirty_sectors * (1ULL << 31),
 						  ca->mi.bucket_size),
 			.sectors	= a.dirty_sectors,
-			.offset		= bucket_to_sector(ca, iter.pos.offset),
+			.bucket		= iter.pos.offset,
 		};
 		heap_add_or_replace(h, e, -fragmentation_cmp, NULL);
 
@@ -152,77 +87,22 @@ static int walk_buckets_to_copygc(struct bch_fs *c)
 	return ret;
 }
 
-static int bucket_inorder_cmp(const void *_l, const void *_r)
-{
-	const struct copygc_heap_entry *l = _l;
-	const struct copygc_heap_entry *r = _r;
-
-	return cmp_int(l->dev, r->dev) ?: cmp_int(l->offset, r->offset);
-}
-
-static int check_copygc_was_done(struct bch_fs *c,
-				 u64 *sectors_not_moved,
-				 u64 *buckets_not_moved)
-{
-	copygc_heap *h = &c->copygc_heap;
-	struct btree_trans trans;
-	struct btree_iter iter;
-	struct bkey_s_c k;
-	struct bch_alloc_v4 a;
-	struct copygc_heap_entry *i;
-	int ret = 0;
-
-	sort(h->data, h->used, sizeof(h->data[0]), bucket_inorder_cmp, NULL);
-
-	bch2_trans_init(&trans, c, 0, 0);
-	bch2_trans_iter_init(&trans, &iter, BTREE_ID_alloc, POS_MIN, 0);
-
-	for (i = h->data; i < h->data + h->used; i++) {
-		struct bch_dev *ca = bch_dev_bkey_exists(c, i->dev);
-
-		bch2_btree_iter_set_pos(&iter, POS(i->dev, sector_to_bucket(ca, i->offset)));
-
-		ret = lockrestart_do(&trans,
-				bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
-		if (ret)
-			break;
-
-		bch2_alloc_to_v4(k, &a);
-
-		if (a.gen == i->gen && a.dirty_sectors) {
-			*sectors_not_moved += a.dirty_sectors;
-			*buckets_not_moved += 1;
-		}
-	}
-	bch2_trans_iter_exit(&trans, &iter);
-
-	bch2_trans_exit(&trans);
-	return ret;
-}
-
 static int bch2_copygc(struct bch_fs *c)
 {
 	copygc_heap *h = &c->copygc_heap;
-	struct copygc_heap_entry e, *i;
+	struct copygc_heap_entry e;
 	struct bch_move_stats move_stats;
-	u64 sectors_to_move = 0, sectors_to_write = 0, sectors_not_moved = 0;
-	u64 sectors_reserved = 0;
-	u64 buckets_to_move, buckets_not_moved = 0;
 	struct bch_dev *ca;
 	unsigned dev_idx;
 	size_t heap_size = 0;
+	struct data_opts data_opts = {
+		.nr_replicas		= 1,
+		.btree_insert_flags	= BTREE_INSERT_USE_RESERVE|JOURNAL_WATERMARK_copygc,
+	};
 	int ret;
 
 	bch_move_stats_init(&move_stats, "copygc");
 
-	/*
-	 * Find buckets with lowest sector counts, skipping completely
-	 * empty buckets, by building a maxheap sorted by sector count,
-	 * and repeatedly replacing the maximum element until all
-	 * buckets have been visited.
-	 */
-	h->used = 0;
-
 	for_each_rw_member(ca, c, dev_idx)
 		heap_size += ca->mi.nbuckets >> 7;
 
@@ -234,21 +114,7 @@ static int bch2_copygc(struct bch_fs *c)
 		}
 	}
 
-	for_each_rw_member(ca, c, dev_idx) {
-		struct bch_dev_usage usage = bch2_dev_usage_read(ca);
-
-		u64 avail = max_t(s64, 0,
-				  usage.d[BCH_DATA_free].buckets +
-				  usage.d[BCH_DATA_need_discard].buckets -
-				  ca->nr_open_buckets -
-				  bch2_dev_buckets_reserved(ca, RESERVE_movinggc));
-
-		avail = min(avail, ca->mi.nbuckets >> 6);
-
-		sectors_reserved += avail * ca->mi.bucket_size;
-	}
-
-	ret = walk_buckets_to_copygc(c);
+	ret = find_buckets_to_copygc(c);
 	if (ret) {
 		bch2_fs_fatal_error(c, "error walking buckets to copygc!");
 		return ret;
@@ -259,68 +125,24 @@ static int bch2_copygc(struct bch_fs *c)
 		return 0;
 	}
 
-	/*
-	 * Our btree node allocations also come out of RESERVE_movingc:
-	 */
-	sectors_reserved = (sectors_reserved * 3) / 4;
-	if (!sectors_reserved) {
-		bch2_fs_fatal_error(c, "stuck, ran out of copygc reserve!");
-		return -1;
-	}
+	heap_resort(h, fragmentation_cmp, NULL);
 
-	for (i = h->data; i < h->data + h->used; i++) {
-		sectors_to_move += i->sectors;
-		sectors_to_write += i->sectors * i->replicas;
-	}
-
-	while (sectors_to_write > sectors_reserved) {
+	while (h->used) {
 		BUG_ON(!heap_pop(h, e, -fragmentation_cmp, NULL));
-		sectors_to_write -= e.sectors * e.replicas;
-	}
-
-	buckets_to_move = h->used;
-
-	if (!buckets_to_move) {
-		bch_err_ratelimited(c, "copygc cannot run - sectors_reserved %llu!",
-				    sectors_reserved);
-		return 0;
-	}
-
-	eytzinger0_sort(h->data, h->used,
-			sizeof(h->data[0]),
-			bucket_offset_cmp, NULL);
-
-	ret = bch2_move_data(c,
-			     0,			POS_MIN,
-			     BTREE_ID_NR,	POS_MAX,
-			     NULL,
-			     writepoint_ptr(&c->copygc_write_point),
-			     copygc_pred, NULL,
-			     &move_stats);
-	if (ret < 0)
-		bch_err(c, "error %i from bch2_move_data() in copygc", ret);
-	if (ret)
-		return ret;
-
-	ret = check_copygc_was_done(c, &sectors_not_moved, &buckets_not_moved);
-	if (ret) {
-		bch_err(c, "error %i from check_copygc_was_done()", ret);
-		return ret;
+		/* not correct w.r.t. device removal */
+
+		ret = bch2_evacuate_bucket(c, POS(e.dev, e.bucket), e.gen, NULL,
+					   writepoint_ptr(&c->copygc_write_point),
+					   DATA_REWRITE, &data_opts,
+					   &move_stats);
+		if (ret < 0)
+			bch_err(c, "error %i from bch2_move_data() in copygc", ret);
+		if (ret)
+			return ret;
 	}
 
-	if (sectors_not_moved)
-		bch_warn_ratelimited(c,
-			"copygc finished but %llu/%llu sectors, %llu/%llu buckets not moved (move stats: moved %llu sectors, raced %llu keys, %llu sectors)",
-			 sectors_not_moved, sectors_to_move,
-			 buckets_not_moved, buckets_to_move,
-			 atomic64_read(&move_stats.sectors_moved),
-			 atomic64_read(&move_stats.keys_raced),
-			 atomic64_read(&move_stats.sectors_raced));
-
-	trace_copygc(c,
-		     atomic64_read(&move_stats.sectors_moved), sectors_not_moved,
-		     buckets_to_move, buckets_not_moved);
-	return 0;
+	trace_copygc(c, atomic64_read(&move_stats.sectors_moved), 0, 0, 0);
+	return ret;
 }
 
 /*