cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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bset.c (33462B)


      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Code for working with individual keys, and sorted sets of keys with in a
      4 * btree node
      5 *
      6 * Copyright 2012 Google, Inc.
      7 */
      8
      9#define pr_fmt(fmt) "bcache: %s() " fmt, __func__
     10
     11#include "util.h"
     12#include "bset.h"
     13
     14#include <linux/console.h>
     15#include <linux/sched/clock.h>
     16#include <linux/random.h>
     17#include <linux/prefetch.h>
     18
     19#ifdef CONFIG_BCACHE_DEBUG
     20
     21void bch_dump_bset(struct btree_keys *b, struct bset *i, unsigned int set)
     22{
     23	struct bkey *k, *next;
     24
     25	for (k = i->start; k < bset_bkey_last(i); k = next) {
     26		next = bkey_next(k);
     27
     28		pr_err("block %u key %u/%u: ", set,
     29		       (unsigned int) ((u64 *) k - i->d), i->keys);
     30
     31		if (b->ops->key_dump)
     32			b->ops->key_dump(b, k);
     33		else
     34			pr_cont("%llu:%llu\n", KEY_INODE(k), KEY_OFFSET(k));
     35
     36		if (next < bset_bkey_last(i) &&
     37		    bkey_cmp(k, b->ops->is_extents ?
     38			     &START_KEY(next) : next) > 0)
     39			pr_err("Key skipped backwards\n");
     40	}
     41}
     42
     43void bch_dump_bucket(struct btree_keys *b)
     44{
     45	unsigned int i;
     46
     47	console_lock();
     48	for (i = 0; i <= b->nsets; i++)
     49		bch_dump_bset(b, b->set[i].data,
     50			      bset_sector_offset(b, b->set[i].data));
     51	console_unlock();
     52}
     53
     54int __bch_count_data(struct btree_keys *b)
     55{
     56	unsigned int ret = 0;
     57	struct btree_iter iter;
     58	struct bkey *k;
     59
     60	if (b->ops->is_extents)
     61		for_each_key(b, k, &iter)
     62			ret += KEY_SIZE(k);
     63	return ret;
     64}
     65
     66void __bch_check_keys(struct btree_keys *b, const char *fmt, ...)
     67{
     68	va_list args;
     69	struct bkey *k, *p = NULL;
     70	struct btree_iter iter;
     71	const char *err;
     72
     73	for_each_key(b, k, &iter) {
     74		if (b->ops->is_extents) {
     75			err = "Keys out of order";
     76			if (p && bkey_cmp(&START_KEY(p), &START_KEY(k)) > 0)
     77				goto bug;
     78
     79			if (bch_ptr_invalid(b, k))
     80				continue;
     81
     82			err =  "Overlapping keys";
     83			if (p && bkey_cmp(p, &START_KEY(k)) > 0)
     84				goto bug;
     85		} else {
     86			if (bch_ptr_bad(b, k))
     87				continue;
     88
     89			err = "Duplicate keys";
     90			if (p && !bkey_cmp(p, k))
     91				goto bug;
     92		}
     93		p = k;
     94	}
     95#if 0
     96	err = "Key larger than btree node key";
     97	if (p && bkey_cmp(p, &b->key) > 0)
     98		goto bug;
     99#endif
    100	return;
    101bug:
    102	bch_dump_bucket(b);
    103
    104	va_start(args, fmt);
    105	vprintk(fmt, args);
    106	va_end(args);
    107
    108	panic("bch_check_keys error:  %s:\n", err);
    109}
    110
    111static void bch_btree_iter_next_check(struct btree_iter *iter)
    112{
    113	struct bkey *k = iter->data->k, *next = bkey_next(k);
    114
    115	if (next < iter->data->end &&
    116	    bkey_cmp(k, iter->b->ops->is_extents ?
    117		     &START_KEY(next) : next) > 0) {
    118		bch_dump_bucket(iter->b);
    119		panic("Key skipped backwards\n");
    120	}
    121}
    122
    123#else
    124
    125static inline void bch_btree_iter_next_check(struct btree_iter *iter) {}
    126
    127#endif
    128
    129/* Keylists */
    130
    131int __bch_keylist_realloc(struct keylist *l, unsigned int u64s)
    132{
    133	size_t oldsize = bch_keylist_nkeys(l);
    134	size_t newsize = oldsize + u64s;
    135	uint64_t *old_keys = l->keys_p == l->inline_keys ? NULL : l->keys_p;
    136	uint64_t *new_keys;
    137
    138	newsize = roundup_pow_of_two(newsize);
    139
    140	if (newsize <= KEYLIST_INLINE ||
    141	    roundup_pow_of_two(oldsize) == newsize)
    142		return 0;
    143
    144	new_keys = krealloc(old_keys, sizeof(uint64_t) * newsize, GFP_NOIO);
    145
    146	if (!new_keys)
    147		return -ENOMEM;
    148
    149	if (!old_keys)
    150		memcpy(new_keys, l->inline_keys, sizeof(uint64_t) * oldsize);
    151
    152	l->keys_p = new_keys;
    153	l->top_p = new_keys + oldsize;
    154
    155	return 0;
    156}
    157
    158/* Pop the top key of keylist by pointing l->top to its previous key */
    159struct bkey *bch_keylist_pop(struct keylist *l)
    160{
    161	struct bkey *k = l->keys;
    162
    163	if (k == l->top)
    164		return NULL;
    165
    166	while (bkey_next(k) != l->top)
    167		k = bkey_next(k);
    168
    169	return l->top = k;
    170}
    171
    172/* Pop the bottom key of keylist and update l->top_p */
    173void bch_keylist_pop_front(struct keylist *l)
    174{
    175	l->top_p -= bkey_u64s(l->keys);
    176
    177	memmove(l->keys,
    178		bkey_next(l->keys),
    179		bch_keylist_bytes(l));
    180}
    181
    182/* Key/pointer manipulation */
    183
    184void bch_bkey_copy_single_ptr(struct bkey *dest, const struct bkey *src,
    185			      unsigned int i)
    186{
    187	BUG_ON(i > KEY_PTRS(src));
    188
    189	/* Only copy the header, key, and one pointer. */
    190	memcpy(dest, src, 2 * sizeof(uint64_t));
    191	dest->ptr[0] = src->ptr[i];
    192	SET_KEY_PTRS(dest, 1);
    193	/* We didn't copy the checksum so clear that bit. */
    194	SET_KEY_CSUM(dest, 0);
    195}
    196
    197bool __bch_cut_front(const struct bkey *where, struct bkey *k)
    198{
    199	unsigned int i, len = 0;
    200
    201	if (bkey_cmp(where, &START_KEY(k)) <= 0)
    202		return false;
    203
    204	if (bkey_cmp(where, k) < 0)
    205		len = KEY_OFFSET(k) - KEY_OFFSET(where);
    206	else
    207		bkey_copy_key(k, where);
    208
    209	for (i = 0; i < KEY_PTRS(k); i++)
    210		SET_PTR_OFFSET(k, i, PTR_OFFSET(k, i) + KEY_SIZE(k) - len);
    211
    212	BUG_ON(len > KEY_SIZE(k));
    213	SET_KEY_SIZE(k, len);
    214	return true;
    215}
    216
    217bool __bch_cut_back(const struct bkey *where, struct bkey *k)
    218{
    219	unsigned int len = 0;
    220
    221	if (bkey_cmp(where, k) >= 0)
    222		return false;
    223
    224	BUG_ON(KEY_INODE(where) != KEY_INODE(k));
    225
    226	if (bkey_cmp(where, &START_KEY(k)) > 0)
    227		len = KEY_OFFSET(where) - KEY_START(k);
    228
    229	bkey_copy_key(k, where);
    230
    231	BUG_ON(len > KEY_SIZE(k));
    232	SET_KEY_SIZE(k, len);
    233	return true;
    234}
    235
    236/* Auxiliary search trees */
    237
    238/* 32 bits total: */
    239#define BKEY_MID_BITS		3
    240#define BKEY_EXPONENT_BITS	7
    241#define BKEY_MANTISSA_BITS	(32 - BKEY_MID_BITS - BKEY_EXPONENT_BITS)
    242#define BKEY_MANTISSA_MASK	((1 << BKEY_MANTISSA_BITS) - 1)
    243
    244struct bkey_float {
    245	unsigned int	exponent:BKEY_EXPONENT_BITS;
    246	unsigned int	m:BKEY_MID_BITS;
    247	unsigned int	mantissa:BKEY_MANTISSA_BITS;
    248} __packed;
    249
    250/*
    251 * BSET_CACHELINE was originally intended to match the hardware cacheline size -
    252 * it used to be 64, but I realized the lookup code would touch slightly less
    253 * memory if it was 128.
    254 *
    255 * It definites the number of bytes (in struct bset) per struct bkey_float in
    256 * the auxiliar search tree - when we're done searching the bset_float tree we
    257 * have this many bytes left that we do a linear search over.
    258 *
    259 * Since (after level 5) every level of the bset_tree is on a new cacheline,
    260 * we're touching one fewer cacheline in the bset tree in exchange for one more
    261 * cacheline in the linear search - but the linear search might stop before it
    262 * gets to the second cacheline.
    263 */
    264
    265#define BSET_CACHELINE		128
    266
    267/* Space required for the btree node keys */
    268static inline size_t btree_keys_bytes(struct btree_keys *b)
    269{
    270	return PAGE_SIZE << b->page_order;
    271}
    272
    273static inline size_t btree_keys_cachelines(struct btree_keys *b)
    274{
    275	return btree_keys_bytes(b) / BSET_CACHELINE;
    276}
    277
    278/* Space required for the auxiliary search trees */
    279static inline size_t bset_tree_bytes(struct btree_keys *b)
    280{
    281	return btree_keys_cachelines(b) * sizeof(struct bkey_float);
    282}
    283
    284/* Space required for the prev pointers */
    285static inline size_t bset_prev_bytes(struct btree_keys *b)
    286{
    287	return btree_keys_cachelines(b) * sizeof(uint8_t);
    288}
    289
    290/* Memory allocation */
    291
    292void bch_btree_keys_free(struct btree_keys *b)
    293{
    294	struct bset_tree *t = b->set;
    295
    296	if (bset_prev_bytes(b) < PAGE_SIZE)
    297		kfree(t->prev);
    298	else
    299		free_pages((unsigned long) t->prev,
    300			   get_order(bset_prev_bytes(b)));
    301
    302	if (bset_tree_bytes(b) < PAGE_SIZE)
    303		kfree(t->tree);
    304	else
    305		free_pages((unsigned long) t->tree,
    306			   get_order(bset_tree_bytes(b)));
    307
    308	free_pages((unsigned long) t->data, b->page_order);
    309
    310	t->prev = NULL;
    311	t->tree = NULL;
    312	t->data = NULL;
    313}
    314
    315int bch_btree_keys_alloc(struct btree_keys *b,
    316			 unsigned int page_order,
    317			 gfp_t gfp)
    318{
    319	struct bset_tree *t = b->set;
    320
    321	BUG_ON(t->data);
    322
    323	b->page_order = page_order;
    324
    325	t->data = (void *) __get_free_pages(__GFP_COMP|gfp, b->page_order);
    326	if (!t->data)
    327		goto err;
    328
    329	t->tree = bset_tree_bytes(b) < PAGE_SIZE
    330		? kmalloc(bset_tree_bytes(b), gfp)
    331		: (void *) __get_free_pages(gfp, get_order(bset_tree_bytes(b)));
    332	if (!t->tree)
    333		goto err;
    334
    335	t->prev = bset_prev_bytes(b) < PAGE_SIZE
    336		? kmalloc(bset_prev_bytes(b), gfp)
    337		: (void *) __get_free_pages(gfp, get_order(bset_prev_bytes(b)));
    338	if (!t->prev)
    339		goto err;
    340
    341	return 0;
    342err:
    343	bch_btree_keys_free(b);
    344	return -ENOMEM;
    345}
    346
    347void bch_btree_keys_init(struct btree_keys *b, const struct btree_keys_ops *ops,
    348			 bool *expensive_debug_checks)
    349{
    350	b->ops = ops;
    351	b->expensive_debug_checks = expensive_debug_checks;
    352	b->nsets = 0;
    353	b->last_set_unwritten = 0;
    354
    355	/*
    356	 * struct btree_keys in embedded in struct btree, and struct
    357	 * bset_tree is embedded into struct btree_keys. They are all
    358	 * initialized as 0 by kzalloc() in mca_bucket_alloc(), and
    359	 * b->set[0].data is allocated in bch_btree_keys_alloc(), so we
    360	 * don't have to initiate b->set[].size and b->set[].data here
    361	 * any more.
    362	 */
    363}
    364
    365/* Binary tree stuff for auxiliary search trees */
    366
    367/*
    368 * return array index next to j when does in-order traverse
    369 * of a binary tree which is stored in a linear array
    370 */
    371static unsigned int inorder_next(unsigned int j, unsigned int size)
    372{
    373	if (j * 2 + 1 < size) {
    374		j = j * 2 + 1;
    375
    376		while (j * 2 < size)
    377			j *= 2;
    378	} else
    379		j >>= ffz(j) + 1;
    380
    381	return j;
    382}
    383
    384/*
    385 * return array index previous to j when does in-order traverse
    386 * of a binary tree which is stored in a linear array
    387 */
    388static unsigned int inorder_prev(unsigned int j, unsigned int size)
    389{
    390	if (j * 2 < size) {
    391		j = j * 2;
    392
    393		while (j * 2 + 1 < size)
    394			j = j * 2 + 1;
    395	} else
    396		j >>= ffs(j);
    397
    398	return j;
    399}
    400
    401/*
    402 * I have no idea why this code works... and I'm the one who wrote it
    403 *
    404 * However, I do know what it does:
    405 * Given a binary tree constructed in an array (i.e. how you normally implement
    406 * a heap), it converts a node in the tree - referenced by array index - to the
    407 * index it would have if you did an inorder traversal.
    408 *
    409 * Also tested for every j, size up to size somewhere around 6 million.
    410 *
    411 * The binary tree starts at array index 1, not 0
    412 * extra is a function of size:
    413 *   extra = (size - rounddown_pow_of_two(size - 1)) << 1;
    414 */
    415static unsigned int __to_inorder(unsigned int j,
    416				  unsigned int size,
    417				  unsigned int extra)
    418{
    419	unsigned int b = fls(j);
    420	unsigned int shift = fls(size - 1) - b;
    421
    422	j  ^= 1U << (b - 1);
    423	j <<= 1;
    424	j  |= 1;
    425	j <<= shift;
    426
    427	if (j > extra)
    428		j -= (j - extra) >> 1;
    429
    430	return j;
    431}
    432
    433/*
    434 * Return the cacheline index in bset_tree->data, where j is index
    435 * from a linear array which stores the auxiliar binary tree
    436 */
    437static unsigned int to_inorder(unsigned int j, struct bset_tree *t)
    438{
    439	return __to_inorder(j, t->size, t->extra);
    440}
    441
    442static unsigned int __inorder_to_tree(unsigned int j,
    443				      unsigned int size,
    444				      unsigned int extra)
    445{
    446	unsigned int shift;
    447
    448	if (j > extra)
    449		j += j - extra;
    450
    451	shift = ffs(j);
    452
    453	j >>= shift;
    454	j  |= roundup_pow_of_two(size) >> shift;
    455
    456	return j;
    457}
    458
    459/*
    460 * Return an index from a linear array which stores the auxiliar binary
    461 * tree, j is the cacheline index of t->data.
    462 */
    463static unsigned int inorder_to_tree(unsigned int j, struct bset_tree *t)
    464{
    465	return __inorder_to_tree(j, t->size, t->extra);
    466}
    467
    468#if 0
    469void inorder_test(void)
    470{
    471	unsigned long done = 0;
    472	ktime_t start = ktime_get();
    473
    474	for (unsigned int size = 2;
    475	     size < 65536000;
    476	     size++) {
    477		unsigned int extra =
    478			(size - rounddown_pow_of_two(size - 1)) << 1;
    479		unsigned int i = 1, j = rounddown_pow_of_two(size - 1);
    480
    481		if (!(size % 4096))
    482			pr_notice("loop %u, %llu per us\n", size,
    483			       done / ktime_us_delta(ktime_get(), start));
    484
    485		while (1) {
    486			if (__inorder_to_tree(i, size, extra) != j)
    487				panic("size %10u j %10u i %10u", size, j, i);
    488
    489			if (__to_inorder(j, size, extra) != i)
    490				panic("size %10u j %10u i %10u", size, j, i);
    491
    492			if (j == rounddown_pow_of_two(size) - 1)
    493				break;
    494
    495			BUG_ON(inorder_prev(inorder_next(j, size), size) != j);
    496
    497			j = inorder_next(j, size);
    498			i++;
    499		}
    500
    501		done += size - 1;
    502	}
    503}
    504#endif
    505
    506/*
    507 * Cacheline/offset <-> bkey pointer arithmetic:
    508 *
    509 * t->tree is a binary search tree in an array; each node corresponds to a key
    510 * in one cacheline in t->set (BSET_CACHELINE bytes).
    511 *
    512 * This means we don't have to store the full index of the key that a node in
    513 * the binary tree points to; to_inorder() gives us the cacheline, and then
    514 * bkey_float->m gives us the offset within that cacheline, in units of 8 bytes.
    515 *
    516 * cacheline_to_bkey() and friends abstract out all the pointer arithmetic to
    517 * make this work.
    518 *
    519 * To construct the bfloat for an arbitrary key we need to know what the key
    520 * immediately preceding it is: we have to check if the two keys differ in the
    521 * bits we're going to store in bkey_float->mantissa. t->prev[j] stores the size
    522 * of the previous key so we can walk backwards to it from t->tree[j]'s key.
    523 */
    524
    525static struct bkey *cacheline_to_bkey(struct bset_tree *t,
    526				      unsigned int cacheline,
    527				      unsigned int offset)
    528{
    529	return ((void *) t->data) + cacheline * BSET_CACHELINE + offset * 8;
    530}
    531
    532static unsigned int bkey_to_cacheline(struct bset_tree *t, struct bkey *k)
    533{
    534	return ((void *) k - (void *) t->data) / BSET_CACHELINE;
    535}
    536
    537static unsigned int bkey_to_cacheline_offset(struct bset_tree *t,
    538					 unsigned int cacheline,
    539					 struct bkey *k)
    540{
    541	return (u64 *) k - (u64 *) cacheline_to_bkey(t, cacheline, 0);
    542}
    543
    544static struct bkey *tree_to_bkey(struct bset_tree *t, unsigned int j)
    545{
    546	return cacheline_to_bkey(t, to_inorder(j, t), t->tree[j].m);
    547}
    548
    549static struct bkey *tree_to_prev_bkey(struct bset_tree *t, unsigned int j)
    550{
    551	return (void *) (((uint64_t *) tree_to_bkey(t, j)) - t->prev[j]);
    552}
    553
    554/*
    555 * For the write set - the one we're currently inserting keys into - we don't
    556 * maintain a full search tree, we just keep a simple lookup table in t->prev.
    557 */
    558static struct bkey *table_to_bkey(struct bset_tree *t, unsigned int cacheline)
    559{
    560	return cacheline_to_bkey(t, cacheline, t->prev[cacheline]);
    561}
    562
    563static inline uint64_t shrd128(uint64_t high, uint64_t low, uint8_t shift)
    564{
    565	low >>= shift;
    566	low  |= (high << 1) << (63U - shift);
    567	return low;
    568}
    569
    570/*
    571 * Calculate mantissa value for struct bkey_float.
    572 * If most significant bit of f->exponent is not set, then
    573 *  - f->exponent >> 6 is 0
    574 *  - p[0] points to bkey->low
    575 *  - p[-1] borrows bits from KEY_INODE() of bkey->high
    576 * if most isgnificant bits of f->exponent is set, then
    577 *  - f->exponent >> 6 is 1
    578 *  - p[0] points to bits from KEY_INODE() of bkey->high
    579 *  - p[-1] points to other bits from KEY_INODE() of
    580 *    bkey->high too.
    581 * See make_bfloat() to check when most significant bit of f->exponent
    582 * is set or not.
    583 */
    584static inline unsigned int bfloat_mantissa(const struct bkey *k,
    585				       struct bkey_float *f)
    586{
    587	const uint64_t *p = &k->low - (f->exponent >> 6);
    588
    589	return shrd128(p[-1], p[0], f->exponent & 63) & BKEY_MANTISSA_MASK;
    590}
    591
    592static void make_bfloat(struct bset_tree *t, unsigned int j)
    593{
    594	struct bkey_float *f = &t->tree[j];
    595	struct bkey *m = tree_to_bkey(t, j);
    596	struct bkey *p = tree_to_prev_bkey(t, j);
    597
    598	struct bkey *l = is_power_of_2(j)
    599		? t->data->start
    600		: tree_to_prev_bkey(t, j >> ffs(j));
    601
    602	struct bkey *r = is_power_of_2(j + 1)
    603		? bset_bkey_idx(t->data, t->data->keys - bkey_u64s(&t->end))
    604		: tree_to_bkey(t, j >> (ffz(j) + 1));
    605
    606	BUG_ON(m < l || m > r);
    607	BUG_ON(bkey_next(p) != m);
    608
    609	/*
    610	 * If l and r have different KEY_INODE values (different backing
    611	 * device), f->exponent records how many least significant bits
    612	 * are different in KEY_INODE values and sets most significant
    613	 * bits to 1 (by +64).
    614	 * If l and r have same KEY_INODE value, f->exponent records
    615	 * how many different bits in least significant bits of bkey->low.
    616	 * See bfloat_mantiss() how the most significant bit of
    617	 * f->exponent is used to calculate bfloat mantissa value.
    618	 */
    619	if (KEY_INODE(l) != KEY_INODE(r))
    620		f->exponent = fls64(KEY_INODE(r) ^ KEY_INODE(l)) + 64;
    621	else
    622		f->exponent = fls64(r->low ^ l->low);
    623
    624	f->exponent = max_t(int, f->exponent - BKEY_MANTISSA_BITS, 0);
    625
    626	/*
    627	 * Setting f->exponent = 127 flags this node as failed, and causes the
    628	 * lookup code to fall back to comparing against the original key.
    629	 */
    630
    631	if (bfloat_mantissa(m, f) != bfloat_mantissa(p, f))
    632		f->mantissa = bfloat_mantissa(m, f) - 1;
    633	else
    634		f->exponent = 127;
    635}
    636
    637static void bset_alloc_tree(struct btree_keys *b, struct bset_tree *t)
    638{
    639	if (t != b->set) {
    640		unsigned int j = roundup(t[-1].size,
    641				     64 / sizeof(struct bkey_float));
    642
    643		t->tree = t[-1].tree + j;
    644		t->prev = t[-1].prev + j;
    645	}
    646
    647	while (t < b->set + MAX_BSETS)
    648		t++->size = 0;
    649}
    650
    651static void bch_bset_build_unwritten_tree(struct btree_keys *b)
    652{
    653	struct bset_tree *t = bset_tree_last(b);
    654
    655	BUG_ON(b->last_set_unwritten);
    656	b->last_set_unwritten = 1;
    657
    658	bset_alloc_tree(b, t);
    659
    660	if (t->tree != b->set->tree + btree_keys_cachelines(b)) {
    661		t->prev[0] = bkey_to_cacheline_offset(t, 0, t->data->start);
    662		t->size = 1;
    663	}
    664}
    665
    666void bch_bset_init_next(struct btree_keys *b, struct bset *i, uint64_t magic)
    667{
    668	if (i != b->set->data) {
    669		b->set[++b->nsets].data = i;
    670		i->seq = b->set->data->seq;
    671	} else
    672		get_random_bytes(&i->seq, sizeof(uint64_t));
    673
    674	i->magic	= magic;
    675	i->version	= 0;
    676	i->keys		= 0;
    677
    678	bch_bset_build_unwritten_tree(b);
    679}
    680
    681/*
    682 * Build auxiliary binary tree 'struct bset_tree *t', this tree is used to
    683 * accelerate bkey search in a btree node (pointed by bset_tree->data in
    684 * memory). After search in the auxiliar tree by calling bset_search_tree(),
    685 * a struct bset_search_iter is returned which indicates range [l, r] from
    686 * bset_tree->data where the searching bkey might be inside. Then a followed
    687 * linear comparison does the exact search, see __bch_bset_search() for how
    688 * the auxiliary tree is used.
    689 */
    690void bch_bset_build_written_tree(struct btree_keys *b)
    691{
    692	struct bset_tree *t = bset_tree_last(b);
    693	struct bkey *prev = NULL, *k = t->data->start;
    694	unsigned int j, cacheline = 1;
    695
    696	b->last_set_unwritten = 0;
    697
    698	bset_alloc_tree(b, t);
    699
    700	t->size = min_t(unsigned int,
    701			bkey_to_cacheline(t, bset_bkey_last(t->data)),
    702			b->set->tree + btree_keys_cachelines(b) - t->tree);
    703
    704	if (t->size < 2) {
    705		t->size = 0;
    706		return;
    707	}
    708
    709	t->extra = (t->size - rounddown_pow_of_two(t->size - 1)) << 1;
    710
    711	/* First we figure out where the first key in each cacheline is */
    712	for (j = inorder_next(0, t->size);
    713	     j;
    714	     j = inorder_next(j, t->size)) {
    715		while (bkey_to_cacheline(t, k) < cacheline) {
    716			prev = k;
    717			k = bkey_next(k);
    718		}
    719
    720		t->prev[j] = bkey_u64s(prev);
    721		t->tree[j].m = bkey_to_cacheline_offset(t, cacheline++, k);
    722	}
    723
    724	while (bkey_next(k) != bset_bkey_last(t->data))
    725		k = bkey_next(k);
    726
    727	t->end = *k;
    728
    729	/* Then we build the tree */
    730	for (j = inorder_next(0, t->size);
    731	     j;
    732	     j = inorder_next(j, t->size))
    733		make_bfloat(t, j);
    734}
    735
    736/* Insert */
    737
    738void bch_bset_fix_invalidated_key(struct btree_keys *b, struct bkey *k)
    739{
    740	struct bset_tree *t;
    741	unsigned int inorder, j = 1;
    742
    743	for (t = b->set; t <= bset_tree_last(b); t++)
    744		if (k < bset_bkey_last(t->data))
    745			goto found_set;
    746
    747	BUG();
    748found_set:
    749	if (!t->size || !bset_written(b, t))
    750		return;
    751
    752	inorder = bkey_to_cacheline(t, k);
    753
    754	if (k == t->data->start)
    755		goto fix_left;
    756
    757	if (bkey_next(k) == bset_bkey_last(t->data)) {
    758		t->end = *k;
    759		goto fix_right;
    760	}
    761
    762	j = inorder_to_tree(inorder, t);
    763
    764	if (j &&
    765	    j < t->size &&
    766	    k == tree_to_bkey(t, j))
    767fix_left:	do {
    768			make_bfloat(t, j);
    769			j = j * 2;
    770		} while (j < t->size);
    771
    772	j = inorder_to_tree(inorder + 1, t);
    773
    774	if (j &&
    775	    j < t->size &&
    776	    k == tree_to_prev_bkey(t, j))
    777fix_right:	do {
    778			make_bfloat(t, j);
    779			j = j * 2 + 1;
    780		} while (j < t->size);
    781}
    782
    783static void bch_bset_fix_lookup_table(struct btree_keys *b,
    784				      struct bset_tree *t,
    785				      struct bkey *k)
    786{
    787	unsigned int shift = bkey_u64s(k);
    788	unsigned int j = bkey_to_cacheline(t, k);
    789
    790	/* We're getting called from btree_split() or btree_gc, just bail out */
    791	if (!t->size)
    792		return;
    793
    794	/*
    795	 * k is the key we just inserted; we need to find the entry in the
    796	 * lookup table for the first key that is strictly greater than k:
    797	 * it's either k's cacheline or the next one
    798	 */
    799	while (j < t->size &&
    800	       table_to_bkey(t, j) <= k)
    801		j++;
    802
    803	/*
    804	 * Adjust all the lookup table entries, and find a new key for any that
    805	 * have gotten too big
    806	 */
    807	for (; j < t->size; j++) {
    808		t->prev[j] += shift;
    809
    810		if (t->prev[j] > 7) {
    811			k = table_to_bkey(t, j - 1);
    812
    813			while (k < cacheline_to_bkey(t, j, 0))
    814				k = bkey_next(k);
    815
    816			t->prev[j] = bkey_to_cacheline_offset(t, j, k);
    817		}
    818	}
    819
    820	if (t->size == b->set->tree + btree_keys_cachelines(b) - t->tree)
    821		return;
    822
    823	/* Possibly add a new entry to the end of the lookup table */
    824
    825	for (k = table_to_bkey(t, t->size - 1);
    826	     k != bset_bkey_last(t->data);
    827	     k = bkey_next(k))
    828		if (t->size == bkey_to_cacheline(t, k)) {
    829			t->prev[t->size] =
    830				bkey_to_cacheline_offset(t, t->size, k);
    831			t->size++;
    832		}
    833}
    834
    835/*
    836 * Tries to merge l and r: l should be lower than r
    837 * Returns true if we were able to merge. If we did merge, l will be the merged
    838 * key, r will be untouched.
    839 */
    840bool bch_bkey_try_merge(struct btree_keys *b, struct bkey *l, struct bkey *r)
    841{
    842	if (!b->ops->key_merge)
    843		return false;
    844
    845	/*
    846	 * Generic header checks
    847	 * Assumes left and right are in order
    848	 * Left and right must be exactly aligned
    849	 */
    850	if (!bch_bkey_equal_header(l, r) ||
    851	     bkey_cmp(l, &START_KEY(r)))
    852		return false;
    853
    854	return b->ops->key_merge(b, l, r);
    855}
    856
    857void bch_bset_insert(struct btree_keys *b, struct bkey *where,
    858		     struct bkey *insert)
    859{
    860	struct bset_tree *t = bset_tree_last(b);
    861
    862	BUG_ON(!b->last_set_unwritten);
    863	BUG_ON(bset_byte_offset(b, t->data) +
    864	       __set_bytes(t->data, t->data->keys + bkey_u64s(insert)) >
    865	       PAGE_SIZE << b->page_order);
    866
    867	memmove((uint64_t *) where + bkey_u64s(insert),
    868		where,
    869		(void *) bset_bkey_last(t->data) - (void *) where);
    870
    871	t->data->keys += bkey_u64s(insert);
    872	bkey_copy(where, insert);
    873	bch_bset_fix_lookup_table(b, t, where);
    874}
    875
    876unsigned int bch_btree_insert_key(struct btree_keys *b, struct bkey *k,
    877			      struct bkey *replace_key)
    878{
    879	unsigned int status = BTREE_INSERT_STATUS_NO_INSERT;
    880	struct bset *i = bset_tree_last(b)->data;
    881	struct bkey *m, *prev = NULL;
    882	struct btree_iter iter;
    883	struct bkey preceding_key_on_stack = ZERO_KEY;
    884	struct bkey *preceding_key_p = &preceding_key_on_stack;
    885
    886	BUG_ON(b->ops->is_extents && !KEY_SIZE(k));
    887
    888	/*
    889	 * If k has preceding key, preceding_key_p will be set to address
    890	 *  of k's preceding key; otherwise preceding_key_p will be set
    891	 * to NULL inside preceding_key().
    892	 */
    893	if (b->ops->is_extents)
    894		preceding_key(&START_KEY(k), &preceding_key_p);
    895	else
    896		preceding_key(k, &preceding_key_p);
    897
    898	m = bch_btree_iter_init(b, &iter, preceding_key_p);
    899
    900	if (b->ops->insert_fixup(b, k, &iter, replace_key))
    901		return status;
    902
    903	status = BTREE_INSERT_STATUS_INSERT;
    904
    905	while (m != bset_bkey_last(i) &&
    906	       bkey_cmp(k, b->ops->is_extents ? &START_KEY(m) : m) > 0) {
    907		prev = m;
    908		m = bkey_next(m);
    909	}
    910
    911	/* prev is in the tree, if we merge we're done */
    912	status = BTREE_INSERT_STATUS_BACK_MERGE;
    913	if (prev &&
    914	    bch_bkey_try_merge(b, prev, k))
    915		goto merged;
    916#if 0
    917	status = BTREE_INSERT_STATUS_OVERWROTE;
    918	if (m != bset_bkey_last(i) &&
    919	    KEY_PTRS(m) == KEY_PTRS(k) && !KEY_SIZE(m))
    920		goto copy;
    921#endif
    922	status = BTREE_INSERT_STATUS_FRONT_MERGE;
    923	if (m != bset_bkey_last(i) &&
    924	    bch_bkey_try_merge(b, k, m))
    925		goto copy;
    926
    927	bch_bset_insert(b, m, k);
    928copy:	bkey_copy(m, k);
    929merged:
    930	return status;
    931}
    932
    933/* Lookup */
    934
    935struct bset_search_iter {
    936	struct bkey *l, *r;
    937};
    938
    939static struct bset_search_iter bset_search_write_set(struct bset_tree *t,
    940						     const struct bkey *search)
    941{
    942	unsigned int li = 0, ri = t->size;
    943
    944	while (li + 1 != ri) {
    945		unsigned int m = (li + ri) >> 1;
    946
    947		if (bkey_cmp(table_to_bkey(t, m), search) > 0)
    948			ri = m;
    949		else
    950			li = m;
    951	}
    952
    953	return (struct bset_search_iter) {
    954		table_to_bkey(t, li),
    955		ri < t->size ? table_to_bkey(t, ri) : bset_bkey_last(t->data)
    956	};
    957}
    958
    959static struct bset_search_iter bset_search_tree(struct bset_tree *t,
    960						const struct bkey *search)
    961{
    962	struct bkey *l, *r;
    963	struct bkey_float *f;
    964	unsigned int inorder, j, n = 1;
    965
    966	do {
    967		unsigned int p = n << 4;
    968
    969		if (p < t->size)
    970			prefetch(&t->tree[p]);
    971
    972		j = n;
    973		f = &t->tree[j];
    974
    975		if (likely(f->exponent != 127)) {
    976			if (f->mantissa >= bfloat_mantissa(search, f))
    977				n = j * 2;
    978			else
    979				n = j * 2 + 1;
    980		} else {
    981			if (bkey_cmp(tree_to_bkey(t, j), search) > 0)
    982				n = j * 2;
    983			else
    984				n = j * 2 + 1;
    985		}
    986	} while (n < t->size);
    987
    988	inorder = to_inorder(j, t);
    989
    990	/*
    991	 * n would have been the node we recursed to - the low bit tells us if
    992	 * we recursed left or recursed right.
    993	 */
    994	if (n & 1) {
    995		l = cacheline_to_bkey(t, inorder, f->m);
    996
    997		if (++inorder != t->size) {
    998			f = &t->tree[inorder_next(j, t->size)];
    999			r = cacheline_to_bkey(t, inorder, f->m);
   1000		} else
   1001			r = bset_bkey_last(t->data);
   1002	} else {
   1003		r = cacheline_to_bkey(t, inorder, f->m);
   1004
   1005		if (--inorder) {
   1006			f = &t->tree[inorder_prev(j, t->size)];
   1007			l = cacheline_to_bkey(t, inorder, f->m);
   1008		} else
   1009			l = t->data->start;
   1010	}
   1011
   1012	return (struct bset_search_iter) {l, r};
   1013}
   1014
   1015struct bkey *__bch_bset_search(struct btree_keys *b, struct bset_tree *t,
   1016			       const struct bkey *search)
   1017{
   1018	struct bset_search_iter i;
   1019
   1020	/*
   1021	 * First, we search for a cacheline, then lastly we do a linear search
   1022	 * within that cacheline.
   1023	 *
   1024	 * To search for the cacheline, there's three different possibilities:
   1025	 *  * The set is too small to have a search tree, so we just do a linear
   1026	 *    search over the whole set.
   1027	 *  * The set is the one we're currently inserting into; keeping a full
   1028	 *    auxiliary search tree up to date would be too expensive, so we
   1029	 *    use a much simpler lookup table to do a binary search -
   1030	 *    bset_search_write_set().
   1031	 *  * Or we use the auxiliary search tree we constructed earlier -
   1032	 *    bset_search_tree()
   1033	 */
   1034
   1035	if (unlikely(!t->size)) {
   1036		i.l = t->data->start;
   1037		i.r = bset_bkey_last(t->data);
   1038	} else if (bset_written(b, t)) {
   1039		/*
   1040		 * Each node in the auxiliary search tree covers a certain range
   1041		 * of bits, and keys above and below the set it covers might
   1042		 * differ outside those bits - so we have to special case the
   1043		 * start and end - handle that here:
   1044		 */
   1045
   1046		if (unlikely(bkey_cmp(search, &t->end) >= 0))
   1047			return bset_bkey_last(t->data);
   1048
   1049		if (unlikely(bkey_cmp(search, t->data->start) < 0))
   1050			return t->data->start;
   1051
   1052		i = bset_search_tree(t, search);
   1053	} else {
   1054		BUG_ON(!b->nsets &&
   1055		       t->size < bkey_to_cacheline(t, bset_bkey_last(t->data)));
   1056
   1057		i = bset_search_write_set(t, search);
   1058	}
   1059
   1060	if (btree_keys_expensive_checks(b)) {
   1061		BUG_ON(bset_written(b, t) &&
   1062		       i.l != t->data->start &&
   1063		       bkey_cmp(tree_to_prev_bkey(t,
   1064			  inorder_to_tree(bkey_to_cacheline(t, i.l), t)),
   1065				search) > 0);
   1066
   1067		BUG_ON(i.r != bset_bkey_last(t->data) &&
   1068		       bkey_cmp(i.r, search) <= 0);
   1069	}
   1070
   1071	while (likely(i.l != i.r) &&
   1072	       bkey_cmp(i.l, search) <= 0)
   1073		i.l = bkey_next(i.l);
   1074
   1075	return i.l;
   1076}
   1077
   1078/* Btree iterator */
   1079
   1080typedef bool (btree_iter_cmp_fn)(struct btree_iter_set,
   1081				 struct btree_iter_set);
   1082
   1083static inline bool btree_iter_cmp(struct btree_iter_set l,
   1084				  struct btree_iter_set r)
   1085{
   1086	return bkey_cmp(l.k, r.k) > 0;
   1087}
   1088
   1089static inline bool btree_iter_end(struct btree_iter *iter)
   1090{
   1091	return !iter->used;
   1092}
   1093
   1094void bch_btree_iter_push(struct btree_iter *iter, struct bkey *k,
   1095			 struct bkey *end)
   1096{
   1097	if (k != end)
   1098		BUG_ON(!heap_add(iter,
   1099				 ((struct btree_iter_set) { k, end }),
   1100				 btree_iter_cmp));
   1101}
   1102
   1103static struct bkey *__bch_btree_iter_init(struct btree_keys *b,
   1104					  struct btree_iter *iter,
   1105					  struct bkey *search,
   1106					  struct bset_tree *start)
   1107{
   1108	struct bkey *ret = NULL;
   1109
   1110	iter->size = ARRAY_SIZE(iter->data);
   1111	iter->used = 0;
   1112
   1113#ifdef CONFIG_BCACHE_DEBUG
   1114	iter->b = b;
   1115#endif
   1116
   1117	for (; start <= bset_tree_last(b); start++) {
   1118		ret = bch_bset_search(b, start, search);
   1119		bch_btree_iter_push(iter, ret, bset_bkey_last(start->data));
   1120	}
   1121
   1122	return ret;
   1123}
   1124
   1125struct bkey *bch_btree_iter_init(struct btree_keys *b,
   1126				 struct btree_iter *iter,
   1127				 struct bkey *search)
   1128{
   1129	return __bch_btree_iter_init(b, iter, search, b->set);
   1130}
   1131
   1132static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter,
   1133						 btree_iter_cmp_fn *cmp)
   1134{
   1135	struct btree_iter_set b __maybe_unused;
   1136	struct bkey *ret = NULL;
   1137
   1138	if (!btree_iter_end(iter)) {
   1139		bch_btree_iter_next_check(iter);
   1140
   1141		ret = iter->data->k;
   1142		iter->data->k = bkey_next(iter->data->k);
   1143
   1144		if (iter->data->k > iter->data->end) {
   1145			WARN_ONCE(1, "bset was corrupt!\n");
   1146			iter->data->k = iter->data->end;
   1147		}
   1148
   1149		if (iter->data->k == iter->data->end)
   1150			heap_pop(iter, b, cmp);
   1151		else
   1152			heap_sift(iter, 0, cmp);
   1153	}
   1154
   1155	return ret;
   1156}
   1157
   1158struct bkey *bch_btree_iter_next(struct btree_iter *iter)
   1159{
   1160	return __bch_btree_iter_next(iter, btree_iter_cmp);
   1161
   1162}
   1163
   1164struct bkey *bch_btree_iter_next_filter(struct btree_iter *iter,
   1165					struct btree_keys *b, ptr_filter_fn fn)
   1166{
   1167	struct bkey *ret;
   1168
   1169	do {
   1170		ret = bch_btree_iter_next(iter);
   1171	} while (ret && fn(b, ret));
   1172
   1173	return ret;
   1174}
   1175
   1176/* Mergesort */
   1177
   1178void bch_bset_sort_state_free(struct bset_sort_state *state)
   1179{
   1180	mempool_exit(&state->pool);
   1181}
   1182
   1183int bch_bset_sort_state_init(struct bset_sort_state *state,
   1184			     unsigned int page_order)
   1185{
   1186	spin_lock_init(&state->time.lock);
   1187
   1188	state->page_order = page_order;
   1189	state->crit_factor = int_sqrt(1 << page_order);
   1190
   1191	return mempool_init_page_pool(&state->pool, 1, page_order);
   1192}
   1193
   1194static void btree_mergesort(struct btree_keys *b, struct bset *out,
   1195			    struct btree_iter *iter,
   1196			    bool fixup, bool remove_stale)
   1197{
   1198	int i;
   1199	struct bkey *k, *last = NULL;
   1200	BKEY_PADDED(k) tmp;
   1201	bool (*bad)(struct btree_keys *, const struct bkey *) = remove_stale
   1202		? bch_ptr_bad
   1203		: bch_ptr_invalid;
   1204
   1205	/* Heapify the iterator, using our comparison function */
   1206	for (i = iter->used / 2 - 1; i >= 0; --i)
   1207		heap_sift(iter, i, b->ops->sort_cmp);
   1208
   1209	while (!btree_iter_end(iter)) {
   1210		if (b->ops->sort_fixup && fixup)
   1211			k = b->ops->sort_fixup(iter, &tmp.k);
   1212		else
   1213			k = NULL;
   1214
   1215		if (!k)
   1216			k = __bch_btree_iter_next(iter, b->ops->sort_cmp);
   1217
   1218		if (bad(b, k))
   1219			continue;
   1220
   1221		if (!last) {
   1222			last = out->start;
   1223			bkey_copy(last, k);
   1224		} else if (!bch_bkey_try_merge(b, last, k)) {
   1225			last = bkey_next(last);
   1226			bkey_copy(last, k);
   1227		}
   1228	}
   1229
   1230	out->keys = last ? (uint64_t *) bkey_next(last) - out->d : 0;
   1231
   1232	pr_debug("sorted %i keys\n", out->keys);
   1233}
   1234
   1235static void __btree_sort(struct btree_keys *b, struct btree_iter *iter,
   1236			 unsigned int start, unsigned int order, bool fixup,
   1237			 struct bset_sort_state *state)
   1238{
   1239	uint64_t start_time;
   1240	bool used_mempool = false;
   1241	struct bset *out = (void *) __get_free_pages(__GFP_NOWARN|GFP_NOWAIT,
   1242						     order);
   1243	if (!out) {
   1244		struct page *outp;
   1245
   1246		BUG_ON(order > state->page_order);
   1247
   1248		outp = mempool_alloc(&state->pool, GFP_NOIO);
   1249		out = page_address(outp);
   1250		used_mempool = true;
   1251		order = state->page_order;
   1252	}
   1253
   1254	start_time = local_clock();
   1255
   1256	btree_mergesort(b, out, iter, fixup, false);
   1257	b->nsets = start;
   1258
   1259	if (!start && order == b->page_order) {
   1260		/*
   1261		 * Our temporary buffer is the same size as the btree node's
   1262		 * buffer, we can just swap buffers instead of doing a big
   1263		 * memcpy()
   1264		 *
   1265		 * Don't worry event 'out' is allocated from mempool, it can
   1266		 * still be swapped here. Because state->pool is a page mempool
   1267		 * creaated by by mempool_init_page_pool(), which allocates
   1268		 * pages by alloc_pages() indeed.
   1269		 */
   1270
   1271		out->magic	= b->set->data->magic;
   1272		out->seq	= b->set->data->seq;
   1273		out->version	= b->set->data->version;
   1274		swap(out, b->set->data);
   1275	} else {
   1276		b->set[start].data->keys = out->keys;
   1277		memcpy(b->set[start].data->start, out->start,
   1278		       (void *) bset_bkey_last(out) - (void *) out->start);
   1279	}
   1280
   1281	if (used_mempool)
   1282		mempool_free(virt_to_page(out), &state->pool);
   1283	else
   1284		free_pages((unsigned long) out, order);
   1285
   1286	bch_bset_build_written_tree(b);
   1287
   1288	if (!start)
   1289		bch_time_stats_update(&state->time, start_time);
   1290}
   1291
   1292void bch_btree_sort_partial(struct btree_keys *b, unsigned int start,
   1293			    struct bset_sort_state *state)
   1294{
   1295	size_t order = b->page_order, keys = 0;
   1296	struct btree_iter iter;
   1297	int oldsize = bch_count_data(b);
   1298
   1299	__bch_btree_iter_init(b, &iter, NULL, &b->set[start]);
   1300
   1301	if (start) {
   1302		unsigned int i;
   1303
   1304		for (i = start; i <= b->nsets; i++)
   1305			keys += b->set[i].data->keys;
   1306
   1307		order = get_order(__set_bytes(b->set->data, keys));
   1308	}
   1309
   1310	__btree_sort(b, &iter, start, order, false, state);
   1311
   1312	EBUG_ON(oldsize >= 0 && bch_count_data(b) != oldsize);
   1313}
   1314
   1315void bch_btree_sort_and_fix_extents(struct btree_keys *b,
   1316				    struct btree_iter *iter,
   1317				    struct bset_sort_state *state)
   1318{
   1319	__btree_sort(b, iter, 0, b->page_order, true, state);
   1320}
   1321
   1322void bch_btree_sort_into(struct btree_keys *b, struct btree_keys *new,
   1323			 struct bset_sort_state *state)
   1324{
   1325	uint64_t start_time = local_clock();
   1326	struct btree_iter iter;
   1327
   1328	bch_btree_iter_init(b, &iter, NULL);
   1329
   1330	btree_mergesort(b, new->set->data, &iter, false, true);
   1331
   1332	bch_time_stats_update(&state->time, start_time);
   1333
   1334	new->set->size = 0; // XXX: why?
   1335}
   1336
   1337#define SORT_CRIT	(4096 / sizeof(uint64_t))
   1338
   1339void bch_btree_sort_lazy(struct btree_keys *b, struct bset_sort_state *state)
   1340{
   1341	unsigned int crit = SORT_CRIT;
   1342	int i;
   1343
   1344	/* Don't sort if nothing to do */
   1345	if (!b->nsets)
   1346		goto out;
   1347
   1348	for (i = b->nsets - 1; i >= 0; --i) {
   1349		crit *= state->crit_factor;
   1350
   1351		if (b->set[i].data->keys < crit) {
   1352			bch_btree_sort_partial(b, i, state);
   1353			return;
   1354		}
   1355	}
   1356
   1357	/* Sort if we'd overflow */
   1358	if (b->nsets + 1 == MAX_BSETS) {
   1359		bch_btree_sort(b, state);
   1360		return;
   1361	}
   1362
   1363out:
   1364	bch_bset_build_written_tree(b);
   1365}
   1366
   1367void bch_btree_keys_stats(struct btree_keys *b, struct bset_stats *stats)
   1368{
   1369	unsigned int i;
   1370
   1371	for (i = 0; i <= b->nsets; i++) {
   1372		struct bset_tree *t = &b->set[i];
   1373		size_t bytes = t->data->keys * sizeof(uint64_t);
   1374		size_t j;
   1375
   1376		if (bset_written(b, t)) {
   1377			stats->sets_written++;
   1378			stats->bytes_written += bytes;
   1379
   1380			stats->floats += t->size - 1;
   1381
   1382			for (j = 1; j < t->size; j++)
   1383				if (t->tree[j].exponent == 127)
   1384					stats->failed++;
   1385		} else {
   1386			stats->sets_unwritten++;
   1387			stats->bytes_unwritten += bytes;
   1388		}
   1389	}
   1390}