path: root/fs/bcachefs/btree_write_buffer.c

// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"
#include "bkey_buf.h"
#include "btree_locking.h"
#include "btree_update.h"
#include "btree_update_interior.h"
#include "btree_write_buffer.h"
#include "disk_accounting.h"
#include "error.h"
#include "extents.h"
#include "journal.h"
#include "journal_io.h"
#include "journal_reclaim.h"

#include <linux/prefetch.h>
#include <linux/sort.h>

static int bch2_btree_write_buffer_journal_flush(struct journal *,
				struct journal_entry_pin *, u64);

static int bch2_journal_keys_to_write_buffer(struct bch_fs *, struct journal_buf *);

static inline bool __wb_key_ref_cmp(const struct wb_key_ref *l, const struct wb_key_ref *r)
{
	return (cmp_int(l->hi, r->hi) ?:
		cmp_int(l->mi, r->mi) ?:
		cmp_int(l->lo, r->lo)) >= 0;
}

static inline bool wb_key_ref_cmp(const struct wb_key_ref *l, const struct wb_key_ref *r)
{
#ifdef CONFIG_X86_64
	int cmp;

	asm("mov   (%[l]), %%rax;"
	    "sub   (%[r]), %%rax;"
	    "mov  8(%[l]), %%rax;"
	    "sbb  8(%[r]), %%rax;"
	    "mov 16(%[l]), %%rax;"
	    "sbb 16(%[r]), %%rax;"
	    : "=@ccae" (cmp)
	    : [l] "r" (l), [r] "r" (r)
	    : "rax", "cc");

	EBUG_ON(cmp != __wb_key_ref_cmp(l, r));
	return cmp;
#else
	return __wb_key_ref_cmp(l, r);
#endif
}

static int wb_key_seq_cmp(const void *_l, const void *_r)
{
	const struct btree_write_buffered_key *l = _l;
	const struct btree_write_buffered_key *r = _r;

	return cmp_int(l->journal_seq, r->journal_seq);
}

/* Compare excluding idx, the low 24 bits: */
static inline bool wb_key_eq(const void *_l, const void *_r)
{
	const struct wb_key_ref *l = _l;
	const struct wb_key_ref *r = _r;

	return !((l->hi ^ r->hi)|
		 (l->mi ^ r->mi)|
		 ((l->lo >> 24) ^ (r->lo >> 24)));
}

static noinline void wb_sort(struct wb_key_ref *base, size_t num)
{
	size_t n = num, a = num / 2;

	if (!a)		/* num < 2 || size == 0 */
		return;

	for (;;) {
		size_t b, c, d;

		if (a)			/* Building heap: sift down --a */
			--a;
		else if (--n)		/* Sorting: Extract root to --n */
			swap(base[0], base[n]);
		else			/* Sort complete */
			break;

		/*
		 * Sift element at "a" down into heap.  This is the
		 * "bottom-up" variant, which significantly reduces
		 * calls to cmp_func(): we find the sift-down path all
		 * the way to the leaves (one compare per level), then
		 * backtrack to find where to insert the target element.
		 *
		 * Because elements tend to sift down close to the leaves,
		 * this uses fewer compares than doing two per level
		 * on the way down.  (A bit more than half as many on
		 * average, 3/4 worst-case.)
		 */
		for (b = a; c = 2*b + 1, (d = c + 1) < n;)
			b = wb_key_ref_cmp(base + c, base + d) ? c : d;
		if (d == n)		/* Special case last leaf with no sibling */
			b = c;

		/* Now backtrack from "b" to the correct location for "a" */
		while (b != a && wb_key_ref_cmp(base + a, base + b))
			b = (b - 1) / 2;
		c = b;			/* Where "a" belongs */
		while (b != a) {	/* Shift it into place */
			b = (b - 1) / 2;
			swap(base[b], base[c]);
		}
	}
}

static noinline int wb_flush_one_slowpath(struct btree_trans *trans,
					  struct btree_iter *iter,
					  struct btree_write_buffered_key *wb)
{
	struct btree_path *path = btree_iter_path(trans, iter);

	bch2_btree_node_unlock_write(trans, path, path->l[0].b);

	trans->journal_res.seq = wb->journal_seq;

	return bch2_trans_update(trans, iter, &wb->k,
				 BTREE_UPDATE_internal_snapshot_node) ?:
		bch2_trans_commit(trans, NULL, NULL,
				  BCH_TRANS_COMMIT_no_enospc|
				  BCH_TRANS_COMMIT_no_check_rw|
				  BCH_TRANS_COMMIT_no_journal_res|
				  BCH_TRANS_COMMIT_journal_reclaim);
}

static inline int wb_flush_one(struct btree_trans *trans, struct btree_iter *iter,
			       struct btree_write_buffered_key *wb,
			       bool *write_locked,
			       bool *accounting_accumulated,
			       size_t *fast)
{
	struct btree_path *path;
	int ret;

	EBUG_ON(!wb->journal_seq);
	EBUG_ON(!trans->c->btree_write_buffer.flushing.pin.seq);
	EBUG_ON(trans->c->btree_write_buffer.flushing.pin.seq > wb->journal_seq);