1 files changed, 761 insertions, 0 deletions

diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
new file mode 100644
index 000000000000..b6310a60d5b7
--- /dev/null
+++ b/fs/bcachefs/move.c
@@ -0,0 +1,761 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "btree_gc.h"
+#include "btree_update.h"
+#include "buckets.h"
+#include "inode.h"
+#include "io.h"
+#include "journal_reclaim.h"
+#include "keylist.h"
+#include "move.h"
+#include "replicas.h"
+#include "super-io.h"
+#include "trace.h"
+
+#include <linux/ioprio.h>
+#include <linux/kthread.h>
+
+#define SECTORS_IN_FLIGHT_PER_DEVICE	2048
+
+struct moving_io {
+	struct list_head	list;
+	struct closure		cl;
+	bool			read_completed;
+
+	unsigned		read_sectors;
+	unsigned		write_sectors;
+
+	struct bch_read_bio	rbio;
+
+	struct migrate_write	write;
+	/* Must be last since it is variable size */
+	struct bio_vec		bi_inline_vecs[0];
+};
+
+struct moving_context {
+	/* Closure for waiting on all reads and writes to complete */
+	struct closure		cl;
+
+	struct bch_move_stats	*stats;
+
+	struct list_head	reads;
+
+	/* in flight sectors: */
+	atomic_t		read_sectors;
+	atomic_t		write_sectors;
+
+	wait_queue_head_t	wait;
+};
+
+static int bch2_migrate_index_update(struct bch_write_op *op)
+{
+	struct bch_fs *c = op->c;
+	struct migrate_write *m =
+		container_of(op, struct migrate_write, op);
+	struct keylist *keys = &op->insert_keys;
+	struct btree_iter iter;
+	int ret = 0;
+
+	bch2_btree_iter_init(&iter, c, BTREE_ID_EXTENTS,
+			     bkey_start_pos(&bch2_keylist_front(keys)->k),
+			     BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+
+	while (1) {
+		struct bkey_s_c k = bch2_btree_iter_peek_slot(&iter);
+		struct bkey_i_extent *insert, *new =
+			bkey_i_to_extent(bch2_keylist_front(keys));
+		BKEY_PADDED(k) _new, _insert;
+		struct bch_extent_ptr *ptr;
+		struct bch_extent_crc_unpacked crc;
+		bool did_work = false;
+		int nr;
+
+		if (btree_iter_err(k)) {
+			ret = bch2_btree_iter_unlock(&iter);
+			break;
+		}
+
+		if (bversion_cmp(k.k->version, new->k.version) ||
+		    !bkey_extent_is_data(k.k) ||
+		    !bch2_extent_matches_ptr(c, bkey_s_c_to_extent(k),
+					     m->ptr, m->offset))
+			goto nomatch;
+
+		if (m->data_cmd == DATA_REWRITE &&
+		    !bch2_extent_has_device(bkey_s_c_to_extent(k),
+					    m->data_opts.rewrite_dev))
+			goto nomatch;
+
+		bkey_reassemble(&_insert.k, k);
+		insert = bkey_i_to_extent(&_insert.k);
+
+		bkey_copy(&_new.k, bch2_keylist_front(keys));
+		new = bkey_i_to_extent(&_new.k);
+
+		bch2_cut_front(iter.pos, &insert->k_i);
+		bch2_cut_back(new->k.p, &insert->k);
+		bch2_cut_back(insert->k.p, &new->k);
+
+		if (m->data_cmd == DATA_REWRITE) {
+			ptr = (struct bch_extent_ptr *)
+				bch2_extent_has_device(extent_i_to_s_c(insert),
+						       m->data_opts.rewrite_dev);
+			bch2_extent_drop_ptr(extent_i_to_s(insert), ptr);
+		}
+
+		extent_for_each_ptr_crc(extent_i_to_s(new), ptr, crc) {
+			if (bch2_extent_has_device(extent_i_to_s_c(insert), ptr->dev)) {
+				/*
+				 * raced with another move op? extent already
+				 * has a pointer to the device we just wrote
+				 * data to
+				 */
+				continue;
+			}
+
+			bch2_extent_crc_append(insert, crc);
+			extent_ptr_append(insert, *ptr);
+			did_work = true;
+		}
+
+		if (!did_work)
+			goto nomatch;
+
+		bch2_extent_narrow_crcs(insert,
+				(struct bch_extent_crc_unpacked) { 0 });
+		bch2_extent_normalize(c, extent_i_to_s(insert).s);
+		bch2_extent_mark_replicas_cached(c, extent_i_to_s(insert),
+						 op->opts.background_target,
+						 op->opts.data_replicas);
+
+		/*
+		 * It's possible we race, and for whatever reason the extent now
+		 * has fewer replicas than when we last looked at it - meaning
+		 * we need to get a disk reservation here:
+		 */
+		nr = bch2_extent_nr_dirty_ptrs(bkey_i_to_s_c(&insert->k_i)) -
+			(bch2_extent_nr_dirty_ptrs(k) + m->nr_ptrs_reserved);
+		if (nr > 0) {
+			/*
+			 * can't call bch2_disk_reservation_add() with btree
+			 * locks held, at least not without a song and dance
+			 */
+			bch2_btree_iter_unlock(&iter);
+
+			ret = bch2_disk_reservation_add(c, &op->res,
+					keylist_sectors(keys) * nr, 0);
+			if (ret)
+				goto out;
+
+			m->nr_ptrs_reserved += nr;
+			goto next;
+		}
+
+		ret = bch2_mark_bkey_replicas(c, BCH_DATA_USER,
+					      extent_i_to_s_c(insert).s_c);
+		if (ret)
+			break;
+
+		ret = bch2_btree_insert_at(c, &op->res,
+				NULL, op_journal_seq(op),
+				BTREE_INSERT_ATOMIC|
+				BTREE_INSERT_NOFAIL|
+				BTREE_INSERT_USE_RESERVE|
+				m->data_opts.btree_insert_flags,
+				BTREE_INSERT_ENTRY(&iter, &insert->k_i));
+		if (!ret)
+			atomic_long_inc(&c->extent_migrate_done);
+		if (ret == -EINTR)
+			ret = 0;
+		if (ret)
+			break;
+next:
+		while (bkey_cmp(iter.pos, bch2_keylist_front(keys)->k.p) >= 0) {
+			bch2_keylist_pop_front(keys);
+			if (bch2_keylist_empty(keys))
+				goto out;
+		}
+
+		bch2_cut_front(iter.pos, bch2_keylist_front(keys));
+		continue;
+nomatch:
+		if (m->ctxt)
+			atomic64_add(k.k->p.offset - iter.pos.offset,
+				     &m->ctxt->stats->sectors_raced);
+		atomic_long_inc(&c->extent_migrate_raced);
+		trace_move_race(&new->k);
+		bch2_btree_iter_next_slot(&iter);
+		goto next;
+	}
+out:
+	bch2_btree_iter_unlock(&iter);
+	return ret;
+}
+
+void bch2_migrate_read_done(struct migrate_write *m, struct bch_read_bio *rbio)
+{
+	/* write bio must own pages: */
+	BUG_ON(!m->op.wbio.bio.bi_vcnt);
+
+	m->ptr		= rbio->pick.ptr;
+	m->offset	= rbio->pos.offset - rbio->pick.crc.offset;
+	m->op.devs_have	= rbio->devs_have;
+	m->op.pos	= rbio->pos;
+	m->op.version	= rbio->version;
+	m->op.crc	= rbio->pick.crc;
+	m->op.wbio.bio.bi_iter.bi_size = m->op.crc.compressed_size << 9;
+
+	if (bch2_csum_type_is_encryption(m->op.crc.csum_type)) {
+		m->op.nonce	= m->op.crc.nonce + m->op.crc.offset;
+		m->op.csum_type = m->op.crc.csum_type;
+	}
+
+	if (m->data_cmd == DATA_REWRITE)
+		bch2_dev_list_drop_dev(&m->op.devs_have, m->data_opts.rewrite_dev);
+}
+
+int bch2_migrate_write_init(struct bch_fs *c, struct migrate_write *m,
+			    struct write_point_specifier wp,
+			    struct bch_io_opts io_opts,
+			    enum data_cmd data_cmd,
+			    struct data_opts data_opts,
+			    struct bkey_s_c k)
+{
+	int ret;
+
+	m->data_cmd	= data_cmd;
+	m->data_opts	= data_opts;
+	m->nr_ptrs_reserved = 0;
+
+	bch2_write_op_init(&m->op, c, io_opts);
+	m->op.compression_type =
+		bch2_compression_opt_to_type[io_opts.background_compression ?:
+					     io_opts.compression];
+	m->op.target	= data_opts.target,
+	m->op.write_point = wp;
+
+	if (m->data_opts.btree_insert_flags & BTREE_INSERT_USE_RESERVE)
+		m->op.alloc_reserve = RESERVE_MOVINGGC;
+
+	m->op.flags |= BCH_WRITE_ONLY_SPECIFIED_DEVS|
+		BCH_WRITE_PAGES_STABLE|
+		BCH_WRITE_PAGES_OWNED|
+		BCH_WRITE_DATA_ENCODED|
+		BCH_WRITE_NOMARK_REPLICAS;
+
+	m->op.nr_replicas	= 1;
+	m->op.nr_replicas_required = 1;
+	m->op.index_update_fn	= bch2_migrate_index_update;
+
+	switch (data_cmd) {
+	case DATA_ADD_REPLICAS: {
+		int nr = (int) io_opts.data_replicas -
+			bch2_extent_nr_dirty_ptrs(k);
+
+		if (nr > 0) {
+			m->op.nr_replicas = m->nr_ptrs_reserved = nr;
+
+			ret = bch2_disk_reservation_get(c, &m->op.res,
+					k.k->size, m->op.nr_replicas, 0);
+			if (ret)
+				return ret;
+		}
+		break;
+	}
+	case DATA_REWRITE:
+		break;
+	case DATA_PROMOTE:
+		m->op.flags	|= BCH_WRITE_ALLOC_NOWAIT;
+		m->op.flags	|= BCH_WRITE_CACHED;
+		break;
+	default:
+		BUG();
+	}
+
+	return 0;
+}
+
+static void move_free(struct closure *cl)
+{
+	struct moving_io *io = container_of(cl, struct moving_io, cl);
+	struct moving_context *ctxt = io->write.ctxt;
+	struct bvec_iter_all iter;
+	struct bio_vec *bv;
+
+	bch2_disk_reservation_put(io->write.op.c, &io->write.op.res);
+
+	bio_for_each_segment_all(bv, &io->write.op.wbio.bio, iter)
+		if (bv->bv_page)
+			__free_page(bv->bv_page);
+
+	wake_up(&ctxt->wait);
+
+	kfree(io);
+}
+
+static void move_write_done(struct closure *cl)
+{
+	struct moving_io *io = container_of(cl, struct moving_io, cl);
+
+	atomic_sub(io->write_sectors, &io->write.ctxt->write_sectors);
+	closure_return_with_destructor(cl, move_free);
+}
+
+static void move_write(struct closure *cl)
+{
+	struct moving_io *io = container_of(cl, struct moving_io, cl);
+
+	if (unlikely(io->rbio.bio.bi_status || io->rbio.hole)) {
+		closure_return_with_destructor(cl, move_free);
+		return;
+	}
+
+	bch2_migrate_read_done(&io->write, &io->rbio);
+
+	atomic_add(io->write_sectors, &io->write.ctxt->write_sectors);
+	closure_call(&io->write.op.cl, bch2_write, NULL, cl);
+	continue_at(cl, move_write_done, NULL);
+}
+
+static inline struct moving_io *next_pending_write(struct moving_context *ctxt)
+{
+	struct moving_io *io =
+		list_first_entry_or_null(&ctxt->reads, struct moving_io, list);
+
+	return io && io->read_completed ? io : NULL;
+}
+
+static void move_read_endio(struct bio *bio)
+{
+	struct moving_io *io = container_of(bio, struct moving_io, rbio.bio);
+	struct moving_context *ctxt = io->write.ctxt;
+
+	atomic_sub(io->read_sectors, &ctxt->read_sectors);
+	io->read_completed = true;
+
+	if (next_pending_write(ctxt))
+		wake_up(&ctxt->wait);
+
+	closure_put(&ctxt->cl);
+}
+
+static void do_pending_writes(struct moving_context *ctxt)
+{
+	struct moving_io *io;
+
+	while ((io = next_pending_write(ctxt))) {
+		list_del(&io->list);
+		closure_call(&io->cl, move_write, NULL, &ctxt->cl);
+	}
+}
+
+#define move_ctxt_wait_event(_ctxt, _cond)			\
+do {								\
+	do_pending_writes(_ctxt);				\
+								\
+	if (_cond)						\
+		break;						\
+	__wait_event((_ctxt)->wait,				\
+		     next_pending_write(_ctxt) || (_cond));	\
+} while (1)
+
+static void bch2_move_ctxt_wait_for_io(struct moving_context *ctxt)
+{
+	unsigned sectors_pending = atomic_read(&ctxt->write_sectors);
+
+	move_ctxt_wait_event(ctxt,
+		!atomic_read(&ctxt->write_sectors) ||
+		atomic_read(&ctxt->write_sectors) != sectors_pending);
+}
+
+static int bch2_move_extent(struct bch_fs *c,
+			    struct moving_context *ctxt,
+			    struct write_point_specifier wp,
+			    struct bch_io_opts io_opts,
+			    struct bkey_s_c_extent e,
+			    enum data_cmd data_cmd,
+			    struct data_opts data_opts)
+{
+	struct moving_io *io;
+	const struct bch_extent_ptr *ptr;
+	struct bch_extent_crc_unpacked crc;
+	unsigned sectors = e.k->size, pages;
+	int ret = -ENOMEM;
+
+	move_ctxt_wait_event(ctxt,
+		atomic_read(&ctxt->write_sectors) <
+		SECTORS_IN_FLIGHT_PER_DEVICE);
+
+	move_ctxt_wait_event(ctxt,
+		atomic_read(&ctxt->read_sectors) <
+		SECTORS_IN_FLIGHT_PER_DEVICE);
+
+	/* write path might have to decompress data: */
+	extent_for_each_ptr_crc(e, ptr, crc)
+		sectors = max_t(unsigned, sectors, crc.uncompressed_size);
+
+	pages = DIV_ROUND_UP(sectors, PAGE_SECTORS);
+	io = kzalloc(sizeof(struct moving_io) +
+		     sizeof(struct bio_vec) * pages, GFP_KERNEL);
+	if (!io)
+		goto err;
+
+	io->write.ctxt		= ctxt;
+	io->read_sectors	= e.k->size;
+	io->write_sectors	= e.k->size;
+
+	bio_init(&io->write.op.wbio.bio, NULL, io->bi_inline_vecs, pages, 0);
+	bio_set_prio(&io->write.op.wbio.bio,
+		     IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
+
+	if (bch2_bio_alloc_pages(&io->write.op.wbio.bio, sectors << 9,
+				 GFP_KERNEL))
+		goto err_free;
+
+	io->rbio.opts = io_opts;
+	bio_init(&io->rbio.bio, NULL, io->bi_inline_vecs, pages, 0);
+	io->rbio.bio.bi_vcnt = pages;
+	bio_set_prio(&io->rbio.bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
+	io->rbio.bio.bi_iter.bi_size = sectors << 9;
+
+	io->rbio.bio.bi_opf		= REQ_OP_READ;
+	io->rbio.bio.bi_iter.bi_sector	= bkey_start_offset(e.k);
+	io->rbio.bio.bi_end_io		= move_read_endio;
+
+	ret = bch2_migrate_write_init(c, &io->write, wp, io_opts,
+				      data_cmd, data_opts, e.s_c);
+	if (ret)
+		goto err_free_pages;
+
+	atomic64_inc(&ctxt->stats->keys_moved);
+	atomic64_add(e.k->size, &ctxt->stats->sectors_moved);
+
+	trace_move_extent(e.k);
+
+	atomic_add(io->read_sectors, &ctxt->read_sectors);
+	list_add_tail(&io->list, &ctxt->reads);
+
+	/*
+	 * dropped by move_read_endio() - guards against use after free of
+	 * ctxt when doing wakeup
+	 */
+	closure_get(&ctxt->cl);
+	bch2_read_extent(c, &io->rbio, e.s_c,
+			 BCH_READ_NODECODE|
+			 BCH_READ_LAST_FRAGMENT);
+	return 0;
+err_free_pages:
+	bio_free_pages(&io->write.op.wbio.bio);
+err_free:
+	kfree(io);
+err:
+	trace_move_alloc_fail(e.k);
+	return ret;
+}
+
+int bch2_move_data(struct bch_fs *c,
+		   struct bch_ratelimit *rate,
+		   struct write_point_specifier wp,
+		   struct bpos start,
+		   struct bpos end,
+		   move_pred_fn pred, void *arg,
+		   struct bch_move_stats *stats)
+{
+	bool kthread = (current->flags & PF_KTHREAD) != 0;
+	struct moving_context ctxt = { .stats = stats };
+	struct bch_io_opts io_opts = bch2_opts_to_inode_opts(c->opts);
+	BKEY_PADDED(k) tmp;
+	struct bkey_s_c k;
+	struct bkey_s_c_extent e;
+	struct data_opts data_opts;
+	enum data_cmd data_cmd;
+	u64 cur_inum = U64_MAX;
+	int ret = 0, ret2;
+
+	closure_init_stack(&ctxt.cl);
+	INIT_LIST_HEAD(&ctxt.reads);
+	init_waitqueue_head(&ctxt.wait);
+
+	stats->data_type = BCH_DATA_USER;
+	bch2_btree_iter_init(&stats->iter, c, BTREE_ID_EXTENTS, start,
+			     BTREE_ITER_PREFETCH);
+
+	if (rate)
+		bch2_ratelimit_reset(rate);
+
+	while (!kthread || !(ret = kthread_should_stop())) {
+		if (rate &&
+		    bch2_ratelimit_delay(rate) &&
+		    (bch2_btree_iter_unlock(&stats->iter),
+		     (ret = bch2_ratelimit_wait_freezable_stoppable(rate))))
+			break;
+peek:
+		k = bch2_btree_iter_peek(&stats->iter);
+		if (!k.k)
+			break;
+		ret = btree_iter_err(k);
+		if (ret)
+			break;
+		if (bkey_cmp(bkey_start_pos(k.k), end) >= 0)
+			break;
+
+		if (!bkey_extent_is_data(k.k))
+			goto next_nondata;
+
+		e = bkey_s_c_to_extent(k);
+
+		if (cur_inum != k.k->p.inode) {
+			struct bch_inode_unpacked inode;
+
+			/* don't hold btree locks while looking up inode: */
+			bch2_btree_iter_unlock(&stats->iter);
+
+			io_opts = bch2_opts_to_inode_opts(c->opts);
+			if (!bch2_inode_find_by_inum(c, k.k->p.inode, &inode))
+				bch2_io_opts_apply(&io_opts, bch2_inode_opts_get(&inode));
+			cur_inum = k.k->p.inode;
+			goto peek;
+		}
+
+		switch ((data_cmd = pred(c, arg, BKEY_TYPE_EXTENTS, e,
+					 &io_opts, &data_opts))) {
+		case DATA_SKIP:
+			goto next;
+		case DATA_SCRUB:
+			BUG();
+		case DATA_ADD_REPLICAS:
+		case DATA_REWRITE:
+		case DATA_PROMOTE:
+			break;
+		default:
+			BUG();
+		}
+
+		/* unlock before doing IO: */
+		bkey_reassemble(&tmp.k, k);
+		k = bkey_i_to_s_c(&tmp.k);
+		bch2_btree_iter_unlock(&stats->iter);
+
+		ret2 = bch2_move_extent(c, &ctxt, wp, io_opts,
+					bkey_s_c_to_extent(k),
+					data_cmd, data_opts);
+		if (ret2) {
+			if (ret2 == -ENOMEM) {
+				/* memory allocation failure, wait for some IO to finish */
+				bch2_move_ctxt_wait_for_io(&ctxt);
+				continue;
+			}
+
+			/* XXX signal failure */
+			goto next;
+		}
+
+		if (rate)
+			bch2_ratelimit_increment(rate, k.k->size);
+next:
+		atomic64_add(k.k->size * bch2_extent_nr_dirty_ptrs(k),
+			     &stats->sectors_seen);
+next_nondata:
+		bch2_btree_iter_next(&stats->iter);
+		bch2_btree_iter_cond_resched(&stats->iter);
+	}
+
+	bch2_btree_iter_unlock(&stats->iter);
+
+	move_ctxt_wait_event(&ctxt, list_empty(&ctxt.reads));
+	closure_sync(&ctxt.cl);
+
+	EBUG_ON(atomic_read(&ctxt.write_sectors));
+
+	trace_move_data(c,
+			atomic64_read(&stats->sectors_moved),
+			atomic64_read(&stats->keys_moved));
+
+	return ret;
+}
+
+static int bch2_gc_data_replicas(struct bch_fs *c)
+{
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	int ret;
+
+	mutex_lock(&c->replicas_gc_lock);
+	bch2_replicas_gc_start(c, (1 << BCH_DATA_USER)|(1 << BCH_DATA_CACHED));
+
+	for_each_btree_key(&iter, c, BTREE_ID_EXTENTS, POS_MIN,
+			   BTREE_ITER_PREFETCH, k) {
+		ret = bch2_mark_bkey_replicas(c, BCH_DATA_USER, k);
+		if (ret)
+			break;
+	}
+	ret = bch2_btree_iter_unlock(&iter) ?: ret;
+
+	bch2_replicas_gc_end(c, ret);
+	mutex_unlock(&c->replicas_gc_lock);
+
+	return ret;
+}
+
+static int bch2_gc_btree_replicas(struct bch_fs *c)
+{
+	struct btree_iter iter;
+	struct btree *b;
+	unsigned id;
+	int ret = 0;
+
+	mutex_lock(&c->replicas_gc_lock);
+	bch2_replicas_gc_start(c, 1 << BCH_DATA_BTREE);
+
+	for (id = 0; id < BTREE_ID_NR; id++) {
+		for_each_btree_node(&iter, c, id, POS_MIN, BTREE_ITER_PREFETCH, b) {
+			ret = bch2_mark_bkey_replicas(c, BCH_DATA_BTREE,
+						      bkey_i_to_s_c(&b->key));
+
+			bch2_btree_iter_cond_resched(&iter);
+		}
+
+		ret = bch2_btree_iter_unlock(&iter) ?: ret;
+	}
+
+	bch2_replicas_gc_end(c, ret);
+	mutex_unlock(&c->replicas_gc_lock);
+
+	return ret;
+}
+
+static int bch2_move_btree(struct bch_fs *c,
+			   move_pred_fn pred,
+			   void *arg,
+			   struct bch_move_stats *stats)
+{
+	struct bch_io_opts io_opts = bch2_opts_to_inode_opts(c->opts);
+	struct btree *b;
+	unsigned id;
+	struct data_opts data_opts;
+	enum data_cmd cmd;
+	int ret = 0;
+
+	stats->data_type = BCH_DATA_BTREE;
+
+	for (id = 0; id < BTREE_ID_NR; id++) {
+		for_each_btree_node(&stats->iter, c, id, POS_MIN, BTREE_ITER_PREFETCH, b) {
+			switch ((cmd = pred(c, arg, BKEY_TYPE_BTREE,
+					    bkey_i_to_s_c_extent(&b->key),
+					    &io_opts,
+					    &data_opts))) {
+			case DATA_SKIP:
+				goto next;
+			case DATA_SCRUB:
+				BUG();
+			case DATA_ADD_REPLICAS:
+			case DATA_REWRITE:
+				break;
+			default:
+				BUG();
+			}
+
+			ret = bch2_btree_node_rewrite(c, &stats->iter,
+					b->data->keys.seq, 0) ?: ret;
+next:
+			bch2_btree_iter_cond_resched(&stats->iter);
+		}
+
+		ret = bch2_btree_iter_unlock(&stats->iter) ?: ret;
+	}
+
+	return ret;
+}
+
+#if 0
+static enum data_cmd scrub_pred(struct bch_fs *c, void *arg,
+				enum bkey_type type,
+				struct bkey_s_c_extent e,
+				struct bch_io_opts *io_opts,
+				struct data_opts *data_opts)
+{
+	return DATA_SCRUB;
+}
+#endif
+
+static enum data_cmd rereplicate_pred(struct bch_fs *c, void *arg,
+				      enum bkey_type type,
+				      struct bkey_s_c_extent e,
+				      struct bch_io_opts *io_opts,
+				      struct data_opts *data_opts)
+{
+	unsigned nr_good = bch2_extent_durability(c, e);
+	unsigned replicas = type == BKEY_TYPE_BTREE
+		? c->opts.metadata_replicas
+		: io_opts->data_replicas;
+
+	if (!nr_good || nr_good >= replicas)
+		return DATA_SKIP;
+
+	data_opts->target		= 0;
+	data_opts->btree_insert_flags = 0;
+	return DATA_ADD_REPLICAS;
+}
+
+static enum data_cmd migrate_pred(struct bch_fs *c, void *arg,
+				  enum bkey_type type,
+				  struct bkey_s_c_extent e,
+				  struct bch_io_opts *io_opts,
+				  struct data_opts *data_opts)
+{
+	struct bch_ioctl_data *op = arg;
+
+	if (!bch2_extent_has_device(e, op->migrate.dev))
+		return DATA_SKIP;
+
+	data_opts->target		= 0;
+	data_opts->btree_insert_flags	= 0;
+	data_opts->rewrite_dev		= op->migrate.dev;
+	return DATA_REWRITE;
+}
+
+int bch2_data_job(struct bch_fs *c,
+		  struct bch_move_stats *stats,
+		  struct bch_ioctl_data op)
+{
+	int ret = 0;
+
+	switch (op.op) {
+	case BCH_DATA_OP_REREPLICATE:
+		stats->data_type = BCH_DATA_JOURNAL;
+		ret = bch2_journal_flush_device_pins(&c->journal, -1);
+
+		ret = bch2_move_btree(c, rereplicate_pred, c, stats) ?: ret;
+		ret = bch2_gc_btree_replicas(c) ?: ret;
+
+		ret = bch2_move_data(c, NULL,
+				     writepoint_hashed((unsigned long) current),
+				     op.start,
+				     op.end,
+				     rereplicate_pred, c, stats) ?: ret;
+		ret = bch2_gc_data_replicas(c) ?: ret;
+		break;
+	case BCH_DATA_OP_MIGRATE:
+		if (op.migrate.dev >= c->sb.nr_devices)
+			return -EINVAL;
+
+		stats->data_type = BCH_DATA_JOURNAL;
+		ret = bch2_journal_flush_device_pins(&c->journal, op.migrate.dev);
+
+		ret = bch2_move_btree(c, migrate_pred, &op, stats) ?: ret;
+		ret = bch2_gc_btree_replicas(c) ?: ret;
+
+		ret = bch2_move_data(c, NULL,
+				     writepoint_hashed((unsigned long) current),
+				     op.start,
+				     op.end,
+				     migrate_pred, &op, stats) ?: ret;
+		ret = bch2_gc_data_replicas(c) ?: ret;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}