1 files changed, 486 insertions, 0 deletions

diff --git a/c_src/libbcachefs/rebalance.c b/c_src/libbcachefs/rebalance.c
new file mode 100644
index 00000000..95f46cb3
--- /dev/null
+++ b/c_src/libbcachefs/rebalance.c
@@ -0,0 +1,486 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "alloc_background.h"
+#include "alloc_foreground.h"
+#include "btree_iter.h"
+#include "btree_update.h"
+#include "btree_write_buffer.h"
+#include "buckets.h"
+#include "clock.h"
+#include "compress.h"
+#include "disk_groups.h"
+#include "errcode.h"
+#include "error.h"
+#include "inode.h"
+#include "move.h"
+#include "rebalance.h"
+#include "subvolume.h"
+#include "super-io.h"
+#include "trace.h"
+
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/sched/cputime.h>
+
+#define REBALANCE_WORK_SCAN_OFFSET	(U64_MAX - 1)
+
+static const char * const bch2_rebalance_state_strs[] = {
+#define x(t) #t,
+	BCH_REBALANCE_STATES()
+	NULL
+#undef x
+};
+
+static int __bch2_set_rebalance_needs_scan(struct btree_trans *trans, u64 inum)
+{
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	struct bkey_i_cookie *cookie;
+	u64 v;
+	int ret;
+
+	bch2_trans_iter_init(trans, &iter, BTREE_ID_rebalance_work,
+			     SPOS(inum, REBALANCE_WORK_SCAN_OFFSET, U32_MAX),
+			     BTREE_ITER_INTENT);
+	k = bch2_btree_iter_peek_slot(&iter);
+	ret = bkey_err(k);
+	if (ret)
+		goto err;
+
+	v = k.k->type == KEY_TYPE_cookie
+		? le64_to_cpu(bkey_s_c_to_cookie(k).v->cookie)
+		: 0;
+
+	cookie = bch2_trans_kmalloc(trans, sizeof(*cookie));
+	ret = PTR_ERR_OR_ZERO(cookie);
+	if (ret)
+		goto err;
+
+	bkey_cookie_init(&cookie->k_i);
+	cookie->k.p = iter.pos;
+	cookie->v.cookie = cpu_to_le64(v + 1);
+
+	ret = bch2_trans_update(trans, &iter, &cookie->k_i, 0);
+err:
+	bch2_trans_iter_exit(trans, &iter);
+	return ret;
+}
+
+int bch2_set_rebalance_needs_scan(struct bch_fs *c, u64 inum)
+{
+	int ret = bch2_trans_do(c, NULL, NULL, BCH_TRANS_COMMIT_no_enospc|BCH_TRANS_COMMIT_lazy_rw,
+			    __bch2_set_rebalance_needs_scan(trans, inum));
+	rebalance_wakeup(c);
+	return ret;
+}
+
+int bch2_set_fs_needs_rebalance(struct bch_fs *c)
+{
+	return bch2_set_rebalance_needs_scan(c, 0);
+}
+
+static int bch2_clear_rebalance_needs_scan(struct btree_trans *trans, u64 inum, u64 cookie)
+{
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	u64 v;
+	int ret;
+
+	bch2_trans_iter_init(trans, &iter, BTREE_ID_rebalance_work,
+			     SPOS(inum, REBALANCE_WORK_SCAN_OFFSET, U32_MAX),
+			     BTREE_ITER_INTENT);
+	k = bch2_btree_iter_peek_slot(&iter);
+	ret = bkey_err(k);
+	if (ret)
+		goto err;
+
+	v = k.k->type == KEY_TYPE_cookie
+		? le64_to_cpu(bkey_s_c_to_cookie(k).v->cookie)
+		: 0;
+
+	if (v == cookie)
+		ret = bch2_btree_delete_at(trans, &iter, 0);
+err:
+	bch2_trans_iter_exit(trans, &iter);
+	return ret;
+}
+
+static struct bkey_s_c next_rebalance_entry(struct btree_trans *trans,
+					    struct btree_iter *work_iter)
+{
+	return !kthread_should_stop()
+		? bch2_btree_iter_peek(work_iter)
+		: bkey_s_c_null;
+}
+
+static int bch2_bkey_clear_needs_rebalance(struct btree_trans *trans,
+					   struct btree_iter *iter,
+					   struct bkey_s_c k)
+{
+	struct bkey_i *n = bch2_bkey_make_mut(trans, iter, &k, 0);
+	int ret = PTR_ERR_OR_ZERO(n);
+	if (ret)
+		return ret;
+
+	extent_entry_drop(bkey_i_to_s(n),
+			  (void *) bch2_bkey_rebalance_opts(bkey_i_to_s_c(n)));
+	return bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc);
+}
+
+static struct bkey_s_c next_rebalance_extent(struct btree_trans *trans,
+			struct bpos work_pos,
+			struct btree_iter *extent_iter,
+			struct data_update_opts *data_opts)
+{
+	struct bch_fs *c = trans->c;
+	struct bkey_s_c k;
+
+	bch2_trans_iter_exit(trans, extent_iter);
+	bch2_trans_iter_init(trans, extent_iter,
+			     work_pos.inode ? BTREE_ID_extents : BTREE_ID_reflink,
+			     work_pos,
+			     BTREE_ITER_ALL_SNAPSHOTS);
+	k = bch2_btree_iter_peek_slot(extent_iter);
+	if (bkey_err(k))
+		return k;
+
+	const struct bch_extent_rebalance *r = k.k ? bch2_bkey_rebalance_opts(k) : NULL;
+	if (!r) {
+		/* raced due to btree write buffer, nothing to do */
+		return bkey_s_c_null;
+	}
+
+	memset(data_opts, 0, sizeof(*data_opts));
+
+	data_opts->rewrite_ptrs		=
+		bch2_bkey_ptrs_need_rebalance(c, k, r->target, r->compression);
+	data_opts->target		= r->target;
+
+	if (!data_opts->rewrite_ptrs) {
+		/*
+		 * device we would want to write to offline? devices in target
+		 * changed?
+		 *
+		 * We'll now need a full scan before this extent is picked up
+		 * again:
+		 */
+		int ret = bch2_bkey_clear_needs_rebalance(trans, extent_iter, k);
+		if (ret)
+			return bkey_s_c_err(ret);
+		return bkey_s_c_null;
+	}
+
+	if (trace_rebalance_extent_enabled()) {
+		struct printbuf buf = PRINTBUF;
+
+		prt_str(&buf, "target=");
+		bch2_target_to_text(&buf, c, r->target);
+		prt_str(&buf, " compression=");
+		struct bch_compression_opt opt = __bch2_compression_decode(r->compression);
+		prt_str(&buf, bch2_compression_opts[opt.type]);
+		prt_str(&buf, " ");
+		bch2_bkey_val_to_text(&buf, c, k);
+
+		trace_rebalance_extent(c, buf.buf);
+		printbuf_exit(&buf);
+	}
+
+	return k;
+}
+
+noinline_for_stack
+static int do_rebalance_extent(struct moving_context *ctxt,
+			       struct bpos work_pos,
+			       struct btree_iter *extent_iter)
+{
+	struct btree_trans *trans = ctxt->trans;
+	struct bch_fs *c = trans->c;
+	struct bch_fs_rebalance *r = &trans->c->rebalance;
+	struct data_update_opts data_opts;
+	struct bch_io_opts io_opts;
+	struct bkey_s_c k;
+	struct bkey_buf sk;
+	int ret;
+
+	ctxt->stats = &r->work_stats;
+	r->state = BCH_REBALANCE_working;
+
+	bch2_bkey_buf_init(&sk);
+
+	ret = bkey_err(k = next_rebalance_extent(trans, work_pos,
+						 extent_iter, &data_opts));
+	if (ret || !k.k)
+		goto out;
+
+	ret = bch2_move_get_io_opts_one(trans, &io_opts, k);
+	if (ret)
+		goto out;
+
+	atomic64_add(k.k->size, &ctxt->stats->sectors_seen);
+
+	/*
+	 * The iterator gets unlocked by __bch2_read_extent - need to
+	 * save a copy of @k elsewhere:
+	 */
+	bch2_bkey_buf_reassemble(&sk, c, k);
+	k = bkey_i_to_s_c(sk.k);
+
+	ret = bch2_move_extent(ctxt, NULL, extent_iter, k, io_opts, data_opts);
+	if (ret) {
+		if (bch2_err_matches(ret, ENOMEM)) {
+			/* memory allocation failure, wait for some IO to finish */
+			bch2_move_ctxt_wait_for_io(ctxt);
+			ret = -BCH_ERR_transaction_restart_nested;
+		}
+
+		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+			goto out;
+
+		/* skip it and continue, XXX signal failure */
+		ret = 0;
+	}
+out:
+	bch2_bkey_buf_exit(&sk, c);
+	return ret;
+}
+
+static bool rebalance_pred(struct bch_fs *c, void *arg,
+			   struct bkey_s_c k,
+			   struct bch_io_opts *io_opts,
+			   struct data_update_opts *data_opts)
+{
+	unsigned target, compression;
+
+	if (k.k->p.inode) {
+		target		= io_opts->background_target;
+		compression	= io_opts->background_compression ?: io_opts->compression;
+	} else {
+		const struct bch_extent_rebalance *r = bch2_bkey_rebalance_opts(k);
+
+		target		= r ? r->target : io_opts->background_target;
+		compression	= r ? r->compression :
+			(io_opts->background_compression ?: io_opts->compression);
+	}
+
+	data_opts->rewrite_ptrs		= bch2_bkey_ptrs_need_rebalance(c, k, target, compression);
+	data_opts->target		= target;
+	return data_opts->rewrite_ptrs != 0;
+}
+
+static int do_rebalance_scan(struct moving_context *ctxt, u64 inum, u64 cookie)
+{
+	struct btree_trans *trans = ctxt->trans;
+	struct bch_fs_rebalance *r = &trans->c->rebalance;
+	int ret;
+
+	bch2_move_stats_init(&r->scan_stats, "rebalance_scan");
+	ctxt->stats = &r->scan_stats;
+
+	if (!inum) {
+		r->scan_start	= BBPOS_MIN;
+		r->scan_end	= BBPOS_MAX;
+	} else {
+		r->scan_start	= BBPOS(BTREE_ID_extents, POS(inum, 0));
+		r->scan_end	= BBPOS(BTREE_ID_extents, POS(inum, U64_MAX));
+	}
+
+	r->state = BCH_REBALANCE_scanning;
+
+	ret = __bch2_move_data(ctxt, r->scan_start, r->scan_end, rebalance_pred, NULL) ?:
+		commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
+			  bch2_clear_rebalance_needs_scan(trans, inum, cookie));
+
+	bch2_move_stats_exit(&r->scan_stats, trans->c);
+	return ret;
+}
+
+static void rebalance_wait(struct bch_fs *c)
+{
+	struct bch_fs_rebalance *r = &c->rebalance;
+	struct io_clock *clock = &c->io_clock[WRITE];
+	u64 now = atomic64_read(&clock->now);
+	u64 min_member_capacity = bch2_min_rw_member_capacity(c);
+
+	if (min_member_capacity == U64_MAX)
+		min_member_capacity = 128 * 2048;
+
+	r->wait_iotime_end		= now + (min_member_capacity >> 6);
+
+	if (r->state != BCH_REBALANCE_waiting) {
+		r->wait_iotime_start	= now;
+		r->wait_wallclock_start	= ktime_get_real_ns();
+		r->state		= BCH_REBALANCE_waiting;
+	}
+
+	bch2_kthread_io_clock_wait(clock, r->wait_iotime_end, MAX_SCHEDULE_TIMEOUT);
+}
+
+static int do_rebalance(struct moving_context *ctxt)
+{
+	struct btree_trans *trans = ctxt->trans;
+	struct bch_fs *c = trans->c;
+	struct bch_fs_rebalance *r = &c->rebalance;
+	struct btree_iter rebalance_work_iter, extent_iter = { NULL };
+	struct bkey_s_c k;
+	int ret = 0;
+
+	bch2_move_stats_init(&r->work_stats, "rebalance_work");
+	bch2_move_stats_init(&r->scan_stats, "rebalance_scan");
+
+	bch2_trans_iter_init(trans, &rebalance_work_iter,
+			     BTREE_ID_rebalance_work, POS_MIN,
+			     BTREE_ITER_ALL_SNAPSHOTS);
+
+	while (!bch2_move_ratelimit(ctxt)) {
+		if (!r->enabled) {
+			bch2_moving_ctxt_flush_all(ctxt);
+			kthread_wait_freezable(r->enabled ||
+					       kthread_should_stop());
+		}
+
+		if (kthread_should_stop())
+			break;
+
+		bch2_trans_begin(trans);
+
+		ret = bkey_err(k = next_rebalance_entry(trans, &rebalance_work_iter));
+		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+			continue;
+		if (ret || !k.k)
+			break;
+
+		ret = k.k->type == KEY_TYPE_cookie
+			? do_rebalance_scan(ctxt, k.k->p.inode,
+					    le64_to_cpu(bkey_s_c_to_cookie(k).v->cookie))
+			: do_rebalance_extent(ctxt, k.k->p, &extent_iter);
+
+		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+			continue;
+		if (ret)
+			break;
+
+		bch2_btree_iter_advance(&rebalance_work_iter);
+	}
+
+	bch2_trans_iter_exit(trans, &extent_iter);
+	bch2_trans_iter_exit(trans, &rebalance_work_iter);
+	bch2_move_stats_exit(&r->scan_stats, c);
+
+	if (!ret &&
+	    !kthread_should_stop() &&
+	    !atomic64_read(&r->work_stats.sectors_seen) &&
+	    !atomic64_read(&r->scan_stats.sectors_seen)) {
+		bch2_trans_unlock_long(trans);
+		rebalance_wait(c);
+	}
+
+	if (!bch2_err_matches(ret, EROFS))
+		bch_err_fn(c, ret);
+	return ret;
+}
+
+static int bch2_rebalance_thread(void *arg)
+{
+	struct bch_fs *c = arg;
+	struct bch_fs_rebalance *r = &c->rebalance;
+	struct moving_context ctxt;
+	int ret;
+
+	set_freezable();
+
+	bch2_moving_ctxt_init(&ctxt, c, NULL, &r->work_stats,
+			      writepoint_ptr(&c->rebalance_write_point),
+			      true);
+
+	while (!kthread_should_stop() &&
+	       !(ret = do_rebalance(&ctxt)))
+		;
+
+	bch2_moving_ctxt_exit(&ctxt);
+
+	return 0;
+}
+
+void bch2_rebalance_status_to_text(struct printbuf *out, struct bch_fs *c)
+{
+	struct bch_fs_rebalance *r = &c->rebalance;
+
+	prt_str(out, bch2_rebalance_state_strs[r->state]);
+	prt_newline(out);
+	printbuf_indent_add(out, 2);
+
+	switch (r->state) {
+	case BCH_REBALANCE_waiting: {
+		u64 now = atomic64_read(&c->io_clock[WRITE].now);
+
+		prt_str(out, "io wait duration:  ");
+		bch2_prt_human_readable_s64(out, r->wait_iotime_end - r->wait_iotime_start);
+		prt_newline(out);
+
+		prt_str(out, "io wait remaining: ");
+		bch2_prt_human_readable_s64(out, r->wait_iotime_end - now);
+		prt_newline(out);
+
+		prt_str(out, "duration waited:   ");
+		bch2_pr_time_units(out, ktime_get_real_ns() - r->wait_wallclock_start);
+		prt_newline(out);
+		break;
+	}
+	case BCH_REBALANCE_working:
+		bch2_move_stats_to_text(out, &r->work_stats);
+		break;
+	case BCH_REBALANCE_scanning:
+		bch2_move_stats_to_text(out, &r->scan_stats);
+		break;
+	}
+	prt_newline(out);
+	printbuf_indent_sub(out, 2);
+}
+
+void bch2_rebalance_stop(struct bch_fs *c)
+{
+	struct task_struct *p;
+
+	c->rebalance.pd.rate.rate = UINT_MAX;
+	bch2_ratelimit_reset(&c->rebalance.pd.rate);
+
+	p = rcu_dereference_protected(c->rebalance.thread, 1);
+	c->rebalance.thread = NULL;
+
+	if (p) {
+		/* for sychronizing with rebalance_wakeup() */
+		synchronize_rcu();
+
+		kthread_stop(p);
+		put_task_struct(p);
+	}
+}
+
+int bch2_rebalance_start(struct bch_fs *c)
+{
+	struct task_struct *p;
+	int ret;
+
+	if (c->rebalance.thread)
+		return 0;
+
+	if (c->opts.nochanges)
+		return 0;
+
+	p = kthread_create(bch2_rebalance_thread, c, "bch-rebalance/%s", c->name);
+	ret = PTR_ERR_OR_ZERO(p);
+	bch_err_msg(c, ret, "creating rebalance thread");
+	if (ret)
+		return ret;
+
+	get_task_struct(p);
+	rcu_assign_pointer(c->rebalance.thread, p);
+	wake_up_process(p);
+	return 0;
+}
+
+void bch2_fs_rebalance_init(struct bch_fs *c)
+{
+	bch2_pd_controller_init(&c->rebalance.pd);
+}