1 files changed, 377 insertions, 119 deletions

diff --git a/fs/bcachefs/reflink.c b/fs/bcachefs/reflink.c
index f457925fa362..441e648f28b5 100644
--- a/fs/bcachefs/reflink.c
+++ b/fs/bcachefs/reflink.c
@@ -15,6 +15,17 @@
 
 #include <linux/sched/signal.h>
 
+static inline bool bkey_extent_is_reflink_data(const struct bkey *k)
+{
+	switch (k->type) {
+	case KEY_TYPE_reflink_v:
+	case KEY_TYPE_indirect_inline_data:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static inline unsigned bkey_type_to_indirect(const struct bkey *k)
 {
 	switch (k->type) {
@@ -30,15 +41,15 @@ static inline unsigned bkey_type_to_indirect(const struct bkey *k)
 /* reflink pointers */
 
 int bch2_reflink_p_validate(struct bch_fs *c, struct bkey_s_c k,
-			    enum bch_validate_flags flags)
+			    struct bkey_validate_context from)
 {
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
 	int ret = 0;
 
-	bkey_fsck_err_on(le64_to_cpu(p.v->idx) < le32_to_cpu(p.v->front_pad),
+	bkey_fsck_err_on(REFLINK_P_IDX(p.v) < le32_to_cpu(p.v->front_pad),
 			 c, reflink_p_front_pad_bad,
 			 "idx < front_pad (%llu < %u)",
-			 le64_to_cpu(p.v->idx), le32_to_cpu(p.v->front_pad));
+			 REFLINK_P_IDX(p.v), le32_to_cpu(p.v->front_pad));
 fsck_err:
 	return ret;
 }
@@ -49,7 +60,7 @@ void bch2_reflink_p_to_text(struct printbuf *out, struct bch_fs *c,
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
 
 	prt_printf(out, "idx %llu front_pad %u back_pad %u",
-	       le64_to_cpu(p.v->idx),
+	       REFLINK_P_IDX(p.v),
 	       le32_to_cpu(p.v->front_pad),
 	       le32_to_cpu(p.v->back_pad));
 }
@@ -65,49 +76,250 @@ bool bch2_reflink_p_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r
 	 */
 	return false;
 
-	if (le64_to_cpu(l.v->idx) + l.k->size != le64_to_cpu(r.v->idx))
+	if (REFLINK_P_IDX(l.v) + l.k->size != REFLINK_P_IDX(r.v))
+		return false;
+
+	if (REFLINK_P_ERROR(l.v) != REFLINK_P_ERROR(r.v))
 		return false;
 
 	bch2_key_resize(l.k, l.k->size + r.k->size);
 	return true;
 }
 
+/* indirect extents */
+
+int bch2_reflink_v_validate(struct bch_fs *c, struct bkey_s_c k,
+			    struct bkey_validate_context from)
+{
+	int ret = 0;
+
+	bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, REFLINK_P_IDX_MAX)),
+			 c, reflink_v_pos_bad,
+			 "indirect extent above maximum position 0:%llu",
+			 REFLINK_P_IDX_MAX);
+
+	ret = bch2_bkey_ptrs_validate(c, k, from);
+fsck_err:
+	return ret;
+}
+
+void bch2_reflink_v_to_text(struct printbuf *out, struct bch_fs *c,
+			    struct bkey_s_c k)
+{
+	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(k);
+
+	prt_printf(out, "refcount: %llu ", le64_to_cpu(r.v->refcount));
+
+	bch2_bkey_ptrs_to_text(out, c, k);
+}
+
+#if 0
+Currently disabled, needs to be debugged:
+
+bool bch2_reflink_v_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
+{
+	struct bkey_s_reflink_v   l = bkey_s_to_reflink_v(_l);
+	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(_r);
+
+	return l.v->refcount == r.v->refcount && bch2_extent_merge(c, _l, _r);
+}
+#endif
+
+/* indirect inline data */
+
+int bch2_indirect_inline_data_validate(struct bch_fs *c, struct bkey_s_c k,
+				       struct bkey_validate_context from)
+{
+	return 0;
+}
+
+void bch2_indirect_inline_data_to_text(struct printbuf *out,
+				       struct bch_fs *c, struct bkey_s_c k)
+{
+	struct bkey_s_c_indirect_inline_data d = bkey_s_c_to_indirect_inline_data(k);
+	unsigned datalen = bkey_inline_data_bytes(k.k);
+
+	prt_printf(out, "refcount %llu datalen %u: %*phN",
+	       le64_to_cpu(d.v->refcount), datalen,
+	       min(datalen, 32U), d.v->data);
+}
+
+/* lookup */
+
+static int bch2_indirect_extent_not_missing(struct btree_trans *trans, struct bkey_s_c_reflink_p p,
+					    bool should_commit)
+{
+	struct bkey_i_reflink_p *new = bch2_bkey_make_mut_noupdate_typed(trans, p.s_c, reflink_p);
+	int ret = PTR_ERR_OR_ZERO(new);
+	if (ret)
+		return ret;
+
+	SET_REFLINK_P_ERROR(&new->v, false);
+	ret = bch2_btree_insert_trans(trans, BTREE_ID_extents, &new->k_i, BTREE_TRIGGER_norun);
+	if (ret)
+		return ret;
+
+	if (!should_commit)
+		return 0;
+
+	return bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc) ?:
+		-BCH_ERR_transaction_restart_nested;
+}
+
+static int bch2_indirect_extent_missing_error(struct btree_trans *trans,
+					      struct bkey_s_c_reflink_p p,
+					      u64 missing_start, u64 missing_end,
+					      bool should_commit)
+{
+	if (REFLINK_P_ERROR(p.v))
+		return 0;
+
+	struct bch_fs *c = trans->c;
+	u64 live_start	= REFLINK_P_IDX(p.v);
+	u64 live_end	= REFLINK_P_IDX(p.v) + p.k->size;
+	u64 refd_start	= live_start	- le32_to_cpu(p.v->front_pad);
+	u64 refd_end	= live_end	+ le32_to_cpu(p.v->back_pad);
+	struct printbuf buf = PRINTBUF;
+	int ret = 0;
+
+	BUG_ON(missing_start	< refd_start);
+	BUG_ON(missing_end	> refd_end);
+
+	if (fsck_err(trans, reflink_p_to_missing_reflink_v,
+		     "pointer to missing indirect extent\n"
+		     "  %s\n"
+		     "  missing range %llu-%llu",
+		     (bch2_bkey_val_to_text(&buf, c, p.s_c), buf.buf),
+		     missing_start, missing_end)) {
+		struct bkey_i_reflink_p *new = bch2_bkey_make_mut_noupdate_typed(trans, p.s_c, reflink_p);
+		ret = PTR_ERR_OR_ZERO(new);
+		if (ret)
+			goto err;
+
+		/*
+		 * Is the missing range not actually needed?
+		 *
+		 * p.v->idx refers to the data that we actually want, but if the
+		 * indirect extent we point to was bigger, front_pad and back_pad
+		 * indicate the range we took a reference on.
+		 */
+
+		if (missing_end <= live_start) {
+			new->v.front_pad = cpu_to_le32(live_start - missing_end);
+		} else if (missing_start >= live_end) {
+			new->v.back_pad = cpu_to_le32(missing_start - live_end);
+		} else {
+			struct bpos new_start	= bkey_start_pos(&new->k);
+			struct bpos new_end	= new->k.p;
+
+			if (missing_start > live_start)
+				new_start.offset += missing_start - live_start;
+			if (missing_end < live_end)
+				new_end.offset -= live_end - missing_end;
+
+			bch2_cut_front(new_start, &new->k_i);
+			bch2_cut_back(new_end, &new->k_i);
+
+			SET_REFLINK_P_ERROR(&new->v, true);
+		}
+
+		ret = bch2_btree_insert_trans(trans, BTREE_ID_extents, &new->k_i, BTREE_TRIGGER_norun);
+		if (ret)
+			goto err;
+
+		if (should_commit)
+			ret =   bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc) ?:
+				-BCH_ERR_transaction_restart_nested;
+	}
+err:
+fsck_err:
+	printbuf_exit(&buf);
+	return ret;
+}
+
+/*
+ * This is used from the read path, which doesn't expect to have to do a
+ * transaction commit, and from triggers, which should not be doing a commit:
+ */
+struct bkey_s_c bch2_lookup_indirect_extent(struct btree_trans *trans,
+					    struct btree_iter *iter,
+					    s64 *offset_into_extent,
+					    struct bkey_s_c_reflink_p p,
+					    bool should_commit,
+					    unsigned iter_flags)
+{
+	BUG_ON(*offset_into_extent < -((s64) le32_to_cpu(p.v->front_pad)));
+	BUG_ON(*offset_into_extent >= p.k->size + le32_to_cpu(p.v->back_pad));
+
+	u64 reflink_offset = REFLINK_P_IDX(p.v) + *offset_into_extent;
+
+	struct bkey_s_c k = bch2_bkey_get_iter(trans, iter, BTREE_ID_reflink,
+				       POS(0, reflink_offset), iter_flags);
+	if (bkey_err(k))
+		return k;
+
+	if (unlikely(!bkey_extent_is_reflink_data(k.k))) {
+		unsigned size = min((u64) k.k->size,
+				    REFLINK_P_IDX(p.v) + p.k->size + le32_to_cpu(p.v->back_pad) -
+				    reflink_offset);
+		bch2_key_resize(&iter->k, size);
+
+		int ret = bch2_indirect_extent_missing_error(trans, p, reflink_offset,
+							     k.k->p.offset, should_commit);
+		if (ret) {
+			bch2_trans_iter_exit(trans, iter);
+			return bkey_s_c_err(ret);
+		}
+	} else if (unlikely(REFLINK_P_ERROR(p.v))) {
+		int ret = bch2_indirect_extent_not_missing(trans, p, should_commit);
+		if (ret) {
+			bch2_trans_iter_exit(trans, iter);
+			return bkey_s_c_err(ret);
+		}
+	}
+
+	*offset_into_extent = reflink_offset - bkey_start_offset(k.k);
+	return k;
+}
+
+/* reflink pointer trigger */
+
 static int trans_trigger_reflink_p_segment(struct btree_trans *trans,
 			struct bkey_s_c_reflink_p p, u64 *idx,
 			enum btree_iter_update_trigger_flags flags)
 {
 	struct bch_fs *c = trans->c;
-	struct btree_iter iter;
-	struct bkey_i *k;
-	__le64 *refcount;
-	int add = !(flags & BTREE_TRIGGER_overwrite) ? 1 : -1;
 	struct printbuf buf = PRINTBUF;
-	int ret;
 
-	k = bch2_bkey_get_mut_noupdate(trans, &iter,
-			BTREE_ID_reflink, POS(0, *idx),
-			BTREE_ITER_with_updates);
-	ret = PTR_ERR_OR_ZERO(k);
+	s64 offset_into_extent = *idx - REFLINK_P_IDX(p.v);
+	struct btree_iter iter;
+	struct bkey_s_c k = bch2_lookup_indirect_extent(trans, &iter, &offset_into_extent, p, false,
+							BTREE_ITER_intent|
+							BTREE_ITER_with_updates);
+	int ret = bkey_err(k);
 	if (ret)
-		goto err;
+		return ret;
 
-	refcount = bkey_refcount(bkey_i_to_s(k));
-	if (!refcount) {
-		bch2_bkey_val_to_text(&buf, c, p.s_c);
-		bch2_trans_inconsistent(trans,
-			"nonexistent indirect extent at %llu while marking\n  %s",
-			*idx, buf.buf);
-		ret = -EIO;
-		goto err;
+	if (!bkey_refcount_c(k)) {
+		if (!(flags & BTREE_TRIGGER_overwrite))
+			ret = -BCH_ERR_missing_indirect_extent;
+		goto next;
 	}
 
+	struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);
+	ret = PTR_ERR_OR_ZERO(new);
+	if (ret)
+		goto err;
+
+	__le64 *refcount = bkey_refcount(bkey_i_to_s(new));
 	if (!*refcount && (flags & BTREE_TRIGGER_overwrite)) {
 		bch2_bkey_val_to_text(&buf, c, p.s_c);
-		bch2_trans_inconsistent(trans,
-			"indirect extent refcount underflow at %llu while marking\n  %s",
-			*idx, buf.buf);
-		ret = -EIO;
-		goto err;
+		prt_printf(&buf, "\n  ");
+		bch2_bkey_val_to_text(&buf, c, k);
+		log_fsck_err(trans, reflink_refcount_underflow,
+			     "indirect extent refcount underflow while marking\n  %s",
+			   buf.buf);
+		goto next;
 	}
 
 	if (flags & BTREE_TRIGGER_insert) {
@@ -115,25 +327,26 @@ static int trans_trigger_reflink_p_segment(struct btree_trans *trans,
 		u64 pad;
 
 		pad = max_t(s64, le32_to_cpu(v->front_pad),
-			    le64_to_cpu(v->idx) - bkey_start_offset(&k->k));
+			    REFLINK_P_IDX(v) - bkey_start_offset(&new->k));
 		BUG_ON(pad > U32_MAX);
 		v->front_pad = cpu_to_le32(pad);
 
 		pad = max_t(s64, le32_to_cpu(v->back_pad),
-			    k->k.p.offset - p.k->size - le64_to_cpu(v->idx));
+			    new->k.p.offset - p.k->size - REFLINK_P_IDX(v));
 		BUG_ON(pad > U32_MAX);
 		v->back_pad = cpu_to_le32(pad);
 	}
 
-	le64_add_cpu(refcount, add);
+	le64_add_cpu(refcount, !(flags & BTREE_TRIGGER_overwrite) ? 1 : -1);
 
 	bch2_btree_iter_set_pos_to_extent_start(&iter);
-	ret = bch2_trans_update(trans, &iter, k, 0);
+	ret = bch2_trans_update(trans, &iter, new, 0);
 	if (ret)
 		goto err;
-
-	*idx = k->k.p.offset;
+next:
+	*idx = k.k->p.offset;
 err:
+fsck_err:
 	bch2_trans_iter_exit(trans, &iter);
 	printbuf_exit(&buf);
 	return ret;
@@ -147,9 +360,7 @@ static s64 gc_trigger_reflink_p_segment(struct btree_trans *trans,
 	struct bch_fs *c = trans->c;
 	struct reflink_gc *r;
 	int add = !(flags & BTREE_TRIGGER_overwrite) ? 1 : -1;
-	u64 start = le64_to_cpu(p.v->idx);
-	u64 end = le64_to_cpu(p.v->idx) + p.k->size;
-	u64 next_idx = end + le32_to_cpu(p.v->back_pad);
+	u64 next_idx = REFLINK_P_IDX(p.v) + p.k->size + le32_to_cpu(p.v->back_pad);
 	s64 ret = 0;
 	struct printbuf buf = PRINTBUF;
 
@@ -168,36 +379,14 @@ static s64 gc_trigger_reflink_p_segment(struct btree_trans *trans,
 	*idx = r->offset;
 	return 0;
 not_found:
-	BUG_ON(!(flags & BTREE_TRIGGER_check_repair));
-
-	if (fsck_err(trans, reflink_p_to_missing_reflink_v,
-		     "pointer to missing indirect extent\n"
-		     "  %s\n"
-		     "  missing range %llu-%llu",
-		     (bch2_bkey_val_to_text(&buf, c, p.s_c), buf.buf),
-		     *idx, next_idx)) {
-		struct bkey_i *update = bch2_bkey_make_mut_noupdate(trans, p.s_c);
-		ret = PTR_ERR_OR_ZERO(update);
+	if (flags & BTREE_TRIGGER_check_repair) {
+		ret = bch2_indirect_extent_missing_error(trans, p, *idx, next_idx, false);
 		if (ret)
 			goto err;
-
-		if (next_idx <= start) {
-			bkey_i_to_reflink_p(update)->v.front_pad = cpu_to_le32(start - next_idx);
-		} else if (*idx >= end) {
-			bkey_i_to_reflink_p(update)->v.back_pad = cpu_to_le32(*idx - end);
-		} else {
-			bkey_error_init(update);
-			update->k.p		= p.k->p;
-			update->k.size		= p.k->size;
-			set_bkey_val_u64s(&update->k, 0);
-		}
-
-		ret = bch2_btree_insert_trans(trans, BTREE_ID_extents, update, BTREE_TRIGGER_norun);
 	}
 
 	*idx = next_idx;
 err:
-fsck_err:
 	printbuf_exit(&buf);
 	return ret;
 }
@@ -210,8 +399,8 @@ static int __trigger_reflink_p(struct btree_trans *trans,
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
 	int ret = 0;
 
-	u64 idx = le64_to_cpu(p.v->idx) - le32_to_cpu(p.v->front_pad);
-	u64 end = le64_to_cpu(p.v->idx) + p.k->size + le32_to_cpu(p.v->back_pad);
+	u64 idx = REFLINK_P_IDX(p.v) - le32_to_cpu(p.v->front_pad);
+	u64 end = REFLINK_P_IDX(p.v) + p.k->size + le32_to_cpu(p.v->back_pad);
 
 	if (flags & BTREE_TRIGGER_transactional) {
 		while (idx < end && !ret)
@@ -253,35 +442,7 @@ int bch2_trigger_reflink_p(struct btree_trans *trans,
 	return trigger_run_overwrite_then_insert(__trigger_reflink_p, trans, btree_id, level, old, new, flags);
 }
 
-/* indirect extents */
-
-int bch2_reflink_v_validate(struct bch_fs *c, struct bkey_s_c k,
-			    enum bch_validate_flags flags)
-{
-	return bch2_bkey_ptrs_validate(c, k, flags);
-}
-
-void bch2_reflink_v_to_text(struct printbuf *out, struct bch_fs *c,
-			    struct bkey_s_c k)
-{
-	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(k);
-
-	prt_printf(out, "refcount: %llu ", le64_to_cpu(r.v->refcount));
-
-	bch2_bkey_ptrs_to_text(out, c, k);
-}
-
-#if 0
-Currently disabled, needs to be debugged:
-
-bool bch2_reflink_v_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
-{
-	struct bkey_s_reflink_v   l = bkey_s_to_reflink_v(_l);
-	struct bkey_s_c_reflink_v r = bkey_s_c_to_reflink_v(_r);
-
-	return l.v->refcount == r.v->refcount && bch2_extent_merge(c, _l, _r);
-}
-#endif
+/* indirect extent trigger */
 
 static inline void
 check_indirect_extent_deleting(struct bkey_s new,
@@ -307,25 +468,6 @@ int bch2_trigger_reflink_v(struct btree_trans *trans,
 	return bch2_trigger_extent(trans, btree_id, level, old, new, flags);
 }
 
-/* indirect inline data */
-
-int bch2_indirect_inline_data_validate(struct bch_fs *c, struct bkey_s_c k,
-				      enum bch_validate_flags flags)
-{
-	return 0;
-}
-
-void bch2_indirect_inline_data_to_text(struct printbuf *out,
-				       struct bch_fs *c, struct bkey_s_c k)
-{
-	struct bkey_s_c_indirect_inline_data d = bkey_s_c_to_indirect_inline_data(k);
-	unsigned datalen = bkey_inline_data_bytes(k.k);
-
-	prt_printf(out, "refcount %llu datalen %u: %*phN",
-	       le64_to_cpu(d.v->refcount), datalen,
-	       min(datalen, 32U), d.v->data);
-}
-
 int bch2_trigger_indirect_inline_data(struct btree_trans *trans,
 			      enum btree_id btree_id, unsigned level,
 			      struct bkey_s_c old, struct bkey_s new,
@@ -336,9 +478,12 @@ int bch2_trigger_indirect_inline_data(struct btree_trans *trans,
 	return 0;
 }
 
+/* create */
+
 static int bch2_make_extent_indirect(struct btree_trans *trans,
 				     struct btree_iter *extent_iter,
-				     struct bkey_i *orig)
+				     struct bkey_i *orig,
+				     bool reflink_p_may_update_opts_field)
 {
 	struct bch_fs *c = trans->c;
 	struct btree_iter reflink_iter = { NULL };
@@ -358,6 +503,14 @@ static int bch2_make_extent_indirect(struct btree_trans *trans,
 	if (ret)
 		goto err;
 
+	/*
+	 * XXX: we're assuming that 56 bits will be enough for the life of the
+	 * filesystem: we need to implement wraparound, with a cursor in the
+	 * logged ops btree:
+	 */
+	if (bkey_ge(reflink_iter.pos, POS(0, REFLINK_P_IDX_MAX - orig->k.size)))
+		return -ENOSPC;
+
 	r_v = bch2_trans_kmalloc(trans, sizeof(__le64) + bkey_bytes(&orig->k));
 	ret = PTR_ERR_OR_ZERO(r_v);
 	if (ret)
@@ -394,7 +547,10 @@ static int bch2_make_extent_indirect(struct btree_trans *trans,
 	memset(&r_p->v, 0, sizeof(r_p->v));
 #endif
 
-	r_p->v.idx = cpu_to_le64(bkey_start_offset(&r_v->k));
+	SET_REFLINK_P_IDX(&r_p->v, bkey_start_offset(&r_v->k));
+
+	if (reflink_p_may_update_opts_field)
+		SET_REFLINK_P_MAY_UPDATE_OPTIONS(&r_p->v, true);
 
 	ret = bch2_trans_update(trans, extent_iter, &r_p->k_i,
 				BTREE_UPDATE_internal_snapshot_node);
@@ -409,7 +565,7 @@ static struct bkey_s_c get_next_src(struct btree_iter *iter, struct bpos end)
 	struct bkey_s_c k;
 	int ret;
 
-	for_each_btree_key_upto_continue_norestart(*iter, end, 0, k, ret) {
+	for_each_btree_key_max_continue_norestart(*iter, end, 0, k, ret) {
 		if (bkey_extent_is_unwritten(k))
 			continue;
 
@@ -426,7 +582,8 @@ s64 bch2_remap_range(struct bch_fs *c,
 		     subvol_inum dst_inum, u64 dst_offset,
 		     subvol_inum src_inum, u64 src_offset,
 		     u64 remap_sectors,
-		     u64 new_i_size, s64 *i_sectors_delta)
+		     u64 new_i_size, s64 *i_sectors_delta,
+		     bool may_change_src_io_path_opts)
 {
 	struct btree_trans *trans;
 	struct btree_iter dst_iter, src_iter;
@@ -439,6 +596,8 @@ s64 bch2_remap_range(struct bch_fs *c,
 	struct bpos src_want;
 	u64 dst_done = 0;
 	u32 dst_snapshot, src_snapshot;
+	bool reflink_p_may_update_opts_field =
+		bch2_request_incompat_feature(c, bcachefs_metadata_version_reflink_p_may_update_opts);
 	int ret = 0, ret2 = 0;
 
 	if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_reflink))
@@ -520,7 +679,8 @@ s64 bch2_remap_range(struct bch_fs *c,
 			src_k = bkey_i_to_s_c(new_src.k);
 
 			ret = bch2_make_extent_indirect(trans, &src_iter,
-						new_src.k);
+						new_src.k,
+						reflink_p_may_update_opts_field);
 			if (ret)
 				continue;
 
@@ -533,11 +693,15 @@ s64 bch2_remap_range(struct bch_fs *c,
 			struct bkey_i_reflink_p *dst_p =
 				bkey_reflink_p_init(new_dst.k);
 
-			u64 offset = le64_to_cpu(src_p.v->idx) +
+			u64 offset = REFLINK_P_IDX(src_p.v) +
 				(src_want.offset -
 				 bkey_start_offset(src_k.k));
 
-			dst_p->v.idx = cpu_to_le64(offset);
+			SET_REFLINK_P_IDX(&dst_p->v, offset);
+
+			if (reflink_p_may_update_opts_field &&
+			    may_change_src_io_path_opts)
+				SET_REFLINK_P_MAY_UPDATE_OPTIONS(&dst_p->v, true);
 		} else {
 			BUG();
 		}
@@ -547,7 +711,7 @@ s64 bch2_remap_range(struct bch_fs *c,
 				min(src_k.k->p.offset - src_want.offset,
 				    dst_end.offset - dst_iter.pos.offset));
 
-		ret =   bch2_bkey_set_needs_rebalance(c, new_dst.k, &opts) ?:
+		ret =   bch2_bkey_set_needs_rebalance(c, &opts, new_dst.k) ?:
 			bch2_extent_update(trans, dst_inum, &dst_iter,
 					new_dst.k, &disk_res,
 					new_i_size, i_sectors_delta,
@@ -591,3 +755,97 @@ err:
 
 	return dst_done ?: ret ?: ret2;
 }
+
+/* fsck */
+
+static int bch2_gc_write_reflink_key(struct btree_trans *trans,
+				     struct btree_iter *iter,
+				     struct bkey_s_c k,
+				     size_t *idx)
+{
+	struct bch_fs *c = trans->c;
+	const __le64 *refcount = bkey_refcount_c(k);
+	struct printbuf buf = PRINTBUF;
+	struct reflink_gc *r;
+	int ret = 0;
+
+	if (!refcount)
+		return 0;
+
+	while ((r = genradix_ptr(&c->reflink_gc_table, *idx)) &&
+	       r->offset < k.k->p.offset)
+		++*idx;
+
+	if (!r ||
+	    r->offset != k.k->p.offset ||
+	    r->size != k.k->size) {
+		bch_err(c, "unexpected inconsistency walking reflink table at gc finish");
+		return -EINVAL;
+	}
+
+	if (fsck_err_on(r->refcount != le64_to_cpu(*refcount),
+			trans, reflink_v_refcount_wrong,
+			"reflink key has wrong refcount:\n"
+			"  %s\n"
+			"  should be %u",
+			(bch2_bkey_val_to_text(&buf, c, k), buf.buf),
+			r->refcount)) {
+		struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);
+		ret = PTR_ERR_OR_ZERO(new);
+		if (ret)
+			goto out;
+
+		if (!r->refcount)
+			new->k.type = KEY_TYPE_deleted;
+		else
+			*bkey_refcount(bkey_i_to_s(new)) = cpu_to_le64(r->refcount);
+		ret = bch2_trans_update(trans, iter, new, 0);
+	}
+out:
+fsck_err:
+	printbuf_exit(&buf);
+	return ret;
+}
+
+int bch2_gc_reflink_done(struct bch_fs *c)
+{
+	size_t idx = 0;
+
+	int ret = bch2_trans_run(c,
+		for_each_btree_key_commit(trans, iter,
+				BTREE_ID_reflink, POS_MIN,
+				BTREE_ITER_prefetch, k,
+				NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
+			bch2_gc_write_reflink_key(trans, &iter, k, &idx)));
+	c->reflink_gc_nr = 0;
+	return ret;
+}
+
+int bch2_gc_reflink_start(struct bch_fs *c)
+{
+	c->reflink_gc_nr = 0;
+
+	int ret = bch2_trans_run(c,
+		for_each_btree_key(trans, iter, BTREE_ID_reflink, POS_MIN,
+				   BTREE_ITER_prefetch, k, ({
+			const __le64 *refcount = bkey_refcount_c(k);
+
+			if (!refcount)
+				continue;
+
+			struct reflink_gc *r = genradix_ptr_alloc(&c->reflink_gc_table,
+							c->reflink_gc_nr++, GFP_KERNEL);
+			if (!r) {
+				ret = -BCH_ERR_ENOMEM_gc_reflink_start;
+				break;
+			}
+
+			r->offset	= k.k->p.offset;
+			r->size		= k.k->size;
+			r->refcount	= 0;
+			0;
+		})));
+
+	bch_err_fn(c, ret);
+	return ret;
+}