bcachefs: Initial commit

Initially forked from drivers/md/bcache, bcachefs is a new copy-on-write
filesystem with every feature you could possibly want.

Website: https://bcachefs.org

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 342 insertions, 0 deletions

diff --git a/fs/bcachefs/rebalance.c b/fs/bcachefs/rebalance.c
new file mode 100644
index 000000000000..04824f667693
--- /dev/null
+++ b/fs/bcachefs/rebalance.c
@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "alloc.h"
+#include "btree_iter.h"
+#include "buckets.h"
+#include "clock.h"
+#include "disk_groups.h"
+#include "extents.h"
+#include "io.h"
+#include "move.h"
+#include "rebalance.h"
+#include "super-io.h"
+#include "trace.h"
+
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/sched/cputime.h>
+
+static inline bool rebalance_ptr_pred(struct bch_fs *c,
+				      const struct bch_extent_ptr *ptr,
+				      struct bch_extent_crc_unpacked crc,
+				      struct bch_io_opts *io_opts)
+{
+	if (io_opts->background_target &&
+	    !bch2_dev_in_target(c, ptr->dev, io_opts->background_target) &&
+	    !ptr->cached)
+		return true;
+
+	if (io_opts->background_compression &&
+	    crc.compression_type !=
+	    bch2_compression_opt_to_type[io_opts->background_compression])
+		return true;
+
+	return false;
+}
+
+void bch2_rebalance_add_key(struct bch_fs *c,
+			    struct bkey_s_c k,
+			    struct bch_io_opts *io_opts)
+{
+	const struct bch_extent_ptr *ptr;
+	struct bch_extent_crc_unpacked crc;
+	struct bkey_s_c_extent e;
+
+	if (!bkey_extent_is_data(k.k))
+		return;
+
+	if (!io_opts->background_target &&
+	    !io_opts->background_compression)
+		return;
+
+	e = bkey_s_c_to_extent(k);
+
+	extent_for_each_ptr_crc(e, ptr, crc)
+		if (rebalance_ptr_pred(c, ptr, crc, io_opts)) {
+			struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
+
+			if (atomic64_add_return(crc.compressed_size,
+						&ca->rebalance_work) ==
+			    crc.compressed_size)
+				rebalance_wakeup(c);
+		}
+}
+
+void bch2_rebalance_add_work(struct bch_fs *c, u64 sectors)
+{
+	if (atomic64_add_return(sectors, &c->rebalance.work_unknown_dev) ==
+	    sectors)
+		rebalance_wakeup(c);
+}
+
+static enum data_cmd rebalance_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)
+{
+	const struct bch_extent_ptr *ptr;
+	struct bch_extent_crc_unpacked crc;
+
+	/* Make sure we have room to add a new pointer: */
+	if (bkey_val_u64s(e.k) + BKEY_EXTENT_PTR_U64s_MAX >
+	    BKEY_EXTENT_VAL_U64s_MAX)
+		return DATA_SKIP;
+
+	extent_for_each_ptr_crc(e, ptr, crc)
+		if (rebalance_ptr_pred(c, ptr, crc, io_opts))
+			goto found;
+
+	return DATA_SKIP;
+found:
+	data_opts->target		= io_opts->background_target;
+	data_opts->btree_insert_flags	= 0;
+	return DATA_ADD_REPLICAS;
+}
+
+struct rebalance_work {
+	int		dev_most_full_idx;
+	unsigned	dev_most_full_percent;
+	u64		dev_most_full_work;
+	u64		dev_most_full_capacity;
+	u64		total_work;
+};
+
+static void rebalance_work_accumulate(struct rebalance_work *w,
+		u64 dev_work, u64 unknown_dev, u64 capacity, int idx)
+{
+	unsigned percent_full;
+	u64 work = dev_work + unknown_dev;
+
+	if (work < dev_work || work < unknown_dev)
+		work = U64_MAX;
+	work = min(work, capacity);
+
+	percent_full = div_u64(work * 100, capacity);
+
+	if (percent_full >= w->dev_most_full_percent) {
+		w->dev_most_full_idx		= idx;
+		w->dev_most_full_percent	= percent_full;
+		w->dev_most_full_work		= work;
+		w->dev_most_full_capacity	= capacity;
+	}
+
+	if (w->total_work + dev_work >= w->total_work &&
+	    w->total_work + dev_work >= dev_work)
+		w->total_work += dev_work;
+}
+
+static struct rebalance_work rebalance_work(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	struct rebalance_work ret = { .dev_most_full_idx = -1 };
+	u64 unknown_dev = atomic64_read(&c->rebalance.work_unknown_dev);
+	unsigned i;
+
+	for_each_online_member(ca, c, i)
+		rebalance_work_accumulate(&ret,
+			atomic64_read(&ca->rebalance_work),
+			unknown_dev,
+			bucket_to_sector(ca, ca->mi.nbuckets -
+					 ca->mi.first_bucket),
+			i);
+
+	rebalance_work_accumulate(&ret,
+		unknown_dev, 0, c->capacity, -1);
+
+	return ret;
+}
+
+static void rebalance_work_reset(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i;
+
+	for_each_online_member(ca, c, i)
+		atomic64_set(&ca->rebalance_work, 0);
+
+	atomic64_set(&c->rebalance.work_unknown_dev, 0);
+}
+
+static unsigned long curr_cputime(void)
+{
+	u64 utime, stime;
+
+	task_cputime_adjusted(current, &utime, &stime);
+	return nsecs_to_jiffies(utime + stime);
+}
+
+static int bch2_rebalance_thread(void *arg)
+{
+	struct bch_fs *c = arg;
+	struct bch_fs_rebalance *r = &c->rebalance;
+	struct io_clock *clock = &c->io_clock[WRITE];
+	struct rebalance_work w, p;
+	unsigned long start, prev_start;
+	unsigned long prev_run_time, prev_run_cputime;
+	unsigned long cputime, prev_cputime;
+	unsigned long io_start;
+	long throttle;
+
+	set_freezable();
+
+	io_start	= atomic_long_read(&clock->now);
+	p		= rebalance_work(c);
+	prev_start	= jiffies;
+	prev_cputime	= curr_cputime();
+
+	while (!kthread_wait_freezable(r->enabled)) {
+		start			= jiffies;
+		cputime			= curr_cputime();
+
+		prev_run_time		= start - prev_start;
+		prev_run_cputime	= cputime - prev_cputime;
+
+		w			= rebalance_work(c);
+		BUG_ON(!w.dev_most_full_capacity);
+
+		if (!w.total_work) {
+			r->state = REBALANCE_WAITING;
+			kthread_wait_freezable(rebalance_work(c).total_work);
+			continue;
+		}
+
+		/*
+		 * If there isn't much work to do, throttle cpu usage:
+		 */
+		throttle = prev_run_cputime * 100 /
+			max(1U, w.dev_most_full_percent) -
+			prev_run_time;
+
+		if (w.dev_most_full_percent < 20 && throttle > 0) {
+			r->state = REBALANCE_THROTTLED;
+			r->throttled_until_iotime = io_start +
+				div_u64(w.dev_most_full_capacity *
+					(20 - w.dev_most_full_percent),
+					50);
+			r->throttled_until_cputime = start + throttle;
+
+			bch2_kthread_io_clock_wait(clock,
+				r->throttled_until_iotime,
+				throttle);
+			continue;
+		}
+
+		/* minimum 1 mb/sec: */
+		r->pd.rate.rate =
+			max_t(u64, 1 << 11,
+			      r->pd.rate.rate *
+			      max(p.dev_most_full_percent, 1U) /
+			      max(w.dev_most_full_percent, 1U));
+
+		io_start	= atomic_long_read(&clock->now);
+		p		= w;
+		prev_start	= start;
+		prev_cputime	= cputime;
+
+		r->state = REBALANCE_RUNNING;
+		memset(&r->move_stats, 0, sizeof(r->move_stats));
+		rebalance_work_reset(c);
+
+		bch2_move_data(c,
+			       /* ratelimiting disabled for now */
+			       NULL, /*  &r->pd.rate, */
+			       writepoint_ptr(&c->rebalance_write_point),
+			       POS_MIN, POS_MAX,
+			       rebalance_pred, NULL,
+			       &r->move_stats);
+	}
+
+	return 0;
+}
+
+ssize_t bch2_rebalance_work_show(struct bch_fs *c, char *buf)
+{
+	char *out = buf, *end = out + PAGE_SIZE;
+	struct bch_fs_rebalance *r = &c->rebalance;
+	struct rebalance_work w = rebalance_work(c);
+	char h1[21], h2[21];
+
+	bch2_hprint(h1, w.dev_most_full_work << 9);
+	bch2_hprint(h2, w.dev_most_full_capacity << 9);
+	out += scnprintf(out, end - out,
+			 "fullest_dev (%i):\t%s/%s\n",
+			 w.dev_most_full_idx, h1, h2);
+
+	bch2_hprint(h1, w.total_work << 9);
+	bch2_hprint(h2, c->capacity << 9);
+	out += scnprintf(out, end - out,
+			 "total work:\t\t%s/%s\n",
+			 h1, h2);
+
+	out += scnprintf(out, end - out,
+			 "rate:\t\t\t%u\n",
+			 r->pd.rate.rate);
+
+	switch (r->state) {
+	case REBALANCE_WAITING:
+		out += scnprintf(out, end - out, "waiting\n");
+		break;
+	case REBALANCE_THROTTLED:
+		bch2_hprint(h1,
+			    (r->throttled_until_iotime -
+			     atomic_long_read(&c->io_clock[WRITE].now)) << 9);
+		out += scnprintf(out, end - out,
+				 "throttled for %lu sec or %s io\n",
+				 (r->throttled_until_cputime - jiffies) / HZ,
+				 h1);
+		break;
+	case REBALANCE_RUNNING:
+		out += scnprintf(out, end - out, "running\n");
+		out += scnprintf(out, end - out, "pos %llu:%llu\n",
+				 r->move_stats.iter.pos.inode,
+				 r->move_stats.iter.pos.offset);
+		break;
+	}
+
+	return out - buf;
+}
+
+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;
+
+	if (c->opts.nochanges)
+		return 0;
+
+	p = kthread_create(bch2_rebalance_thread, c, "bch_rebalance");
+	if (IS_ERR(p))
+		return PTR_ERR(p);
+
+	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);
+
+	atomic64_set(&c->rebalance.work_unknown_dev, S64_MAX);
+}