// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2010 Kent Overstreet <[email protected]>
*
* Uses a block device as cache for other block devices; optimized for SSDs.
* All allocation is done in buckets, which should match the erase block size
* of the device.
*
* Buckets containing cached data are kept on a heap sorted by priority;
* bucket priority is increased on cache hit, and periodically all the buckets
* on the heap have their priority scaled down. This currently is just used as
* an LRU but in the future should allow for more intelligent heuristics.
*
* Buckets have an 8 bit counter; freeing is accomplished by incrementing the
* counter. Garbage collection is used to remove stale pointers.
*
* Indexing is done via a btree; nodes are not necessarily fully sorted, rather
* as keys are inserted we only sort the pages that have not yet been written.
* When garbage collection is run, we resort the entire node.
*
* All configuration is done via sysfs; see Documentation/admin-guide/bcache.rst.
*/
#include "bcache.h"
#include "btree.h"
#include "debug.h"
#include "extents.h"
#include "writeback.h"
static void sort_key_next(struct btree_iter *iter,
struct btree_iter_set *i)
{
i->k = bkey_next(i->k);
if (i->k == i->end)
*i = iter->heap.data[--iter->heap.nr];
}
static bool new_bch_key_sort_cmp(const void *l, const void *r, void *args)
{
struct btree_iter_set *_l = (struct btree_iter_set *)l;
struct btree_iter_set *_r = (struct btree_iter_set *)r;
int64_t c = bkey_cmp(_l->k, _r->k);
return !(c ? c > 0 : _l->k < _r->k);
}
static bool __ptr_invalid(struct cache_set *c, const struct bkey *k)
{
unsigned int i;
for (i = 0; i < KEY_PTRS(k); i++)
if (ptr_available(c, k, i)) {
struct cache *ca = c->cache;
size_t bucket = PTR_BUCKET_NR(c, k, i);
size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
if (KEY_SIZE(k) + r > c->cache->sb.bucket_size ||
bucket < ca->sb.first_bucket ||
bucket >= ca->sb.nbuckets)
return true;
}
return false;
}
/* Common among btree and extent ptrs */
static const char *bch_ptr_status(struct cache_set *c, const struct bkey *k)
{
unsigned int i;
for (i = 0; i < KEY_PTRS(k); i++)
if (ptr_available(c, k, i)) {
struct cache *ca = c->cache;
size_t bucket = PTR_BUCKET_NR(c, k, i);
size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
if (KEY_SIZE(k) + r > c->cache->sb.bucket_size)
return "bad, length too big";
if (bucket < ca->sb.first_bucket)
return "bad, short offset";
if (bucket >= ca->sb.nbuckets)
return "bad, offset past end of device";
if (ptr_stale(c, k, i))
return "stale";
}
if (!bkey_cmp(k, &ZERO_KEY))
return "bad, null key";
if (!KEY_PTRS(k))
return "bad, no pointers";
if (!KEY_SIZE(k))
return "zeroed key";
return "";
}
void bch_extent_to_text(char *buf, size_t size, const struct bkey *k)
{
unsigned int i = 0;
char *out = buf, *end = buf + size;
#define p(...) (out += scnprintf(out, end - out, __VA_ARGS__))
p("%llu:%llu len %llu -> [", KEY_INODE(k), KEY_START(k), KEY_SIZE(k));
for (i = 0; i < KEY_PTRS(k); i++) {
if (i)
p(", ");
if (PTR_DEV(k, i) == PTR_CHECK_DEV)
p("check dev");
else
p("%llu:%llu gen %llu", PTR_DEV(k, i),
PTR_OFFSET(k, i), PTR_GEN(k, i));
}
p("]");
if (KEY_DIRTY(k))
p(" dirty");
if (KEY_CSUM(k))
p(" cs%llu %llx", KEY_CSUM(k), k->ptr[1]);
#undef p
}
static void bch_bkey_dump(struct btree_keys *keys, const struct bkey *k)
{
struct btree *b = container_of(keys, struct btree, keys);
unsigned int j;
char buf[80];
bch_extent_to_text(buf, sizeof(buf), k);
pr_cont(" %s", buf);
for (j = 0; j < KEY_PTRS(k); j++) {
size_t n = PTR_BUCKET_NR(b->c, k, j);
pr_cont(" bucket %zu", n);
if (n >= b->c->cache->sb.first_bucket && n < b->c->cache->sb.nbuckets)
pr_cont(" prio %i",
PTR_BUCKET(b->c, k, j)->prio);
}
pr_cont(" %s\n", bch_ptr_status(b->c, k));
}
/* Btree ptrs */
bool __bch_btree_ptr_invalid(struct cache_set *c, const struct bkey *k)
{
char buf[80];
if (!KEY_PTRS(k) || !KEY_SIZE(k) || KEY_DIRTY(k))
goto bad;
if (__ptr_invalid(c, k))
goto bad;
return false;
bad:
bch_extent_to_text(buf, sizeof(buf), k);
cache_bug(c, "spotted btree ptr %s: %s", buf, bch_ptr_status(c, k));
return true;
}
static bool bch_btree_ptr_invalid(struct btree_keys *bk, const struct bkey *k)
{
struct btree *b = container_of(bk, struct btree, keys);
return __bch_btree_ptr_invalid(b->c, k);
}
static bool btree_ptr_bad_expensive(struct btree *b, const struct bkey *k)
{
unsigned int i;
char buf[80];
struct bucket *g;
if (mutex_trylock(&b->c->bucket_lock)) {
for (i = 0; i < KEY_PTRS(k); i++)
if (ptr_available(b->c, k, i)) {
g = PTR_BUCKET(b->c, k, i);
if (KEY_DIRTY(k) ||
g->prio != BTREE_PRIO ||
(b->c->gc_mark_valid &&
GC_MARK(g) != GC_MARK_METADATA))
goto err;
}
mutex_unlock(&b->c->bucket_lock);
}
return false;
err:
mutex_unlock(&b->c->bucket_lock);
bch_extent_to_text(buf, sizeof(buf), k);
btree_bug(b,
"inconsistent btree pointer %s: bucket %zi pin %i prio %i gen %i last_gc %i mark %llu",
buf, PTR_BUCKET_NR(b->c, k, i), atomic_read(&g->pin),
g->prio, g->gen, g->last_gc, GC_MARK(g));
return true;
}
static bool bch_btree_ptr_bad(struct btree_keys *bk, const struct bkey *k)
{
struct btree *b = container_of(bk, struct btree, keys);
unsigned int i;
if (!bkey_cmp(k, &ZERO_KEY) ||
!KEY_PTRS(k) ||
bch_ptr_invalid(bk, k))
return true;
for (i = 0; i < KEY_PTRS(k); i++)
if (!ptr_available(b->c, k, i) ||
ptr_stale(b->c, k, i))
return true;
if (expensive_debug_checks(b->c) &&
btree_ptr_bad_expensive(b, k))
return true;
return false;
}
static bool bch_btree_ptr_insert_fixup(struct btree_keys *bk,
struct bkey *insert,
struct btree_iter *iter,
struct bkey *replace_key)
{
struct btree *b = container_of(bk, struct btree, keys);
if (!KEY_OFFSET(insert))
btree_current_write(b)->prio_blocked++;
return false;
}
const struct btree_keys_ops bch_btree_keys_ops = {
.sort_cmp = new_bch_key_sort_cmp,
.insert_fixup = bch_btree_ptr_insert_fixup,
.key_invalid = bch_btree_ptr_invalid,
.key_bad = bch_btree_ptr_bad,
.key_to_text = bch_extent_to_text,
.key_dump = bch_bkey_dump,
};
/* Extents */
/*
* Returns true if l > r - unless l == r, in which case returns true if l is
* older than r.
*
* Necessary for btree_sort_fixup() - if there are multiple keys that compare
* equal in different sets, we have to process them newest to oldest.
*/
static bool new_bch_extent_sort_cmp(const void *l, const void *r, void __always_unused *args)
{
struct btree_iter_set *_l = (struct btree_iter_set *)l;
struct btree_iter_set *_r = (struct btree_iter_set *)r;
int64_t c = bkey_cmp(&START_KEY(_l->k), &START_KEY(_r->k));
return !(c ? c > 0 : _l->k < _r->k);
}
static inline void new_btree_iter_swap(void *iter1, void *iter2, void __always_unused *args)
{
struct btree_iter_set *_iter1 = iter1;
struct btree_iter_set *_iter2 = iter2;
swap(*_iter1, *_iter2);
}
static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter,
struct bkey *tmp)
{
const struct min_heap_callbacks callbacks = {
.less = new_bch_extent_sort_cmp,
.swp = new_btree_iter_swap,
};
while (iter->heap.nr > 1) {
struct btree_iter_set *top = iter->heap.data, *i = top + 1;
if (iter->heap.nr > 2 &&
!new_bch_extent_sort_cmp(&i[0], &i[1], NULL))
i++;
if (bkey_cmp(top->k, &START_KEY(i->k)) <= 0)
break;
if (!KEY_SIZE(i->k)) {
sort_key_next(iter, i);
min_heap_sift_down(&iter->heap, i - top, &callbacks, NULL);
continue;
}
if (top->k > i->k) {
if (bkey_cmp(top->k, i->k) >= 0)
sort_key_next(iter, i);
else
bch_cut_front(top->k, i->k);
min_heap_sift_down(&iter->heap, i - top, &callbacks, NULL);
} else {
/* can't happen because of comparison func */
BUG_ON(!bkey_cmp(&START_KEY(top->k), &START_KEY(i->k)));
if (bkey_cmp(i->k, top->k) < 0) {
bkey_copy(tmp, top->k);
bch_cut_back(&START_KEY(i->k), tmp);
bch_cut_front(i->k, top->k);
min_heap_sift_down(&iter->heap, 0, &callbacks, NULL);
return tmp;
} else {
bch_cut_back(&START_KEY(i->k), top->k);
}
}
}
return NULL;
}
static void bch_subtract_dirty(struct bkey *k,
struct cache_set *c,
uint64_t offset,
int sectors)
{
if (KEY_DIRTY(k))
bcache_dev_sectors_dirty_add(c, KEY_INODE(k),
offset, -sectors);
}
static bool bch_extent_insert_fixup(struct btree_keys *b,
struct bkey *insert,
struct btree_iter *iter,
struct bkey *replace_key)
{
struct cache_set *c = container_of(b, struct btree, keys)->c;
uint64_t old_offset;
unsigned int old_size, sectors_found = 0;
BUG_ON(!KEY_OFFSET(insert));
BUG_ON(!KEY_SIZE(insert));
while (1) {
struct bkey *k = bch_btree_iter_next(iter);
if (!k)
break;
if (bkey_cmp(&START_KEY(k), insert) >= 0) {
if (KEY_SIZE(k))
break;
else
continue;
}
if (bkey_cmp(k, &START_KEY(insert)) <= 0)
continue;
old_offset = KEY_START(k);
old_size = KEY_SIZE(k);
/*
* We might overlap with 0 size extents; we can't skip these
* because if they're in the set we're inserting to we have to
* adjust them so they don't overlap with the key we're
* inserting. But we don't want to check them for replace
* operations.
*/
if (replace_key && KEY_SIZE(k)) {
/*
* k might have been split since we inserted/found the
* key we're replacing
*/
unsigned int i;
uint64_t offset = KEY_START(k) -
KEY_START(replace_key);
/* But it must be a subset of the replace key */
if (KEY_START(k) < KEY_START(replace_key) ||
KEY_OFFSET(k) > KEY_OFFSET(replace_key))
goto check_failed;
/* We didn't find a key that we were supposed to */
if (KEY_START(k) > KEY_START(insert) + sectors_found)
goto check_failed;
if (!bch_bkey_equal_header(k, replace_key))
goto check_failed;
/* skip past gen */
offset <<= 8;
BUG_ON(!KEY_PTRS(replace_key));
for (i = 0; i < KEY_PTRS(replace_key); i++)
if (k->ptr[i] != replace_key->ptr[i] + offset)
goto check_failed;
sectors_found = KEY_OFFSET(k) - KEY_START(insert);
}
if (bkey_cmp(insert, k) < 0 &&
bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0) {
/*
* We overlapped in the middle of an existing key: that
* means we have to split the old key. But we have to do
* slightly different things depending on whether the
* old key has been written out yet.
*/
struct bkey *top;
bch_subtract_dirty(k, c, KEY_START(insert),
KEY_SIZE(insert));
if (bkey_written(b, k)) {
/*
* We insert a new key to cover the top of the
* old key, and the old key is modified in place
* to represent the bottom split.
*
* It's completely arbitrary whether the new key
* is the top or the bottom, but it has to match
* up with what btree_sort_fixup() does - it
* doesn't check for this kind of overlap, it
* depends on us inserting a new key for the top
* here.
*/
top = bch_bset_search(b, bset_tree_last(b),
insert);
bch_bset_insert(b, top, k);
} else {
BKEY_PADDED(key) temp;
bkey_copy(&temp.key, k);
bch_bset_insert(b, k, &temp.key);
top = bkey_next(k);
}
bch_cut_front(insert, top);
bch_cut_back(&START_KEY(insert), k);
bch_bset_fix_invalidated_key(b, k);
goto out;
}
if (bkey_cmp(insert, k) < 0) {
bch_cut_front(insert, k);
} else {
if (bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0)
old_offset = KEY_START(insert);
if (bkey_written(b, k) &&
bkey_cmp(&START_KEY(insert), &START_KEY(k)) <= 0) {
/*
* Completely overwrote, so we don't have to
* invalidate the binary search tree
*/
bch_cut_front(k, k);
} else {
__bch_cut_back(&START_KEY(insert), k);
bch_bset_fix_invalidated_key(b, k);
}
}
bch_subtract_dirty(k, c, old_offset, old_size - KEY_SIZE(k));
}
check_failed:
if (replace_key) {
if (!sectors_found) {
return true;
} else if (sectors_found < KEY_SIZE(insert)) {
SET_KEY_OFFSET(insert, KEY_OFFSET(insert) -
(KEY_SIZE(insert) - sectors_found));
SET_KEY_SIZE(insert, sectors_found);
}
}
out:
if (KEY_DIRTY(insert))
bcache_dev_sectors_dirty_add(c, KEY_INODE(insert),
KEY_START(insert),
KEY_SIZE(insert));
return false;
}
bool __bch_extent_invalid(struct cache_set *c, const struct bkey *k)
{
char buf[80];
if (!KEY_SIZE(k))
return true;
if (KEY_SIZE(k) > KEY_OFFSET(k))
goto bad;
if (__ptr_invalid(c, k))
goto bad;
return false;
bad:
bch_extent_to_text(buf, sizeof(buf), k);
cache_bug(c, "spotted extent %s: %s", buf, bch_ptr_status(c, k));
return true;
}
static bool bch_extent_invalid(struct btree_keys *bk, const struct bkey *k)
{
struct btree *b = container_of(bk, struct btree, keys);
return __bch_extent_invalid(b->c, k);
}
static bool bch_extent_bad_expensive(struct btree *b, const struct bkey *k,
unsigned int ptr)
{
struct bucket *g = PTR_BUCKET(b->c, k, ptr);
char buf[80];
if (mutex_trylock(&b->c->bucket_lock)) {
if (b->c->gc_mark_valid &&
(!GC_MARK(g) ||
GC_MARK(g) == GC_MARK_METADATA ||
(GC_MARK(g) != GC_MARK_DIRTY && KEY_DIRTY(k))))
goto err;
if (g->prio == BTREE_PRIO)
goto err;
mutex_unlock(&b->c->bucket_lock);
}
return false;
err:
mutex_unlock(&b->c->bucket_lock);
bch_extent_to_text(buf, sizeof(buf), k);
btree_bug(b,
"inconsistent extent pointer %s:\nbucket %zu pin %i prio %i gen %i last_gc %i mark %llu",
buf, PTR_BUCKET_NR(b->c, k, ptr), atomic_read(&g->pin),
g->prio, g->gen, g->last_gc, GC_MARK(g));
return true;
}
static bool bch_extent_bad(struct btree_keys *bk, const struct bkey *k)
{
struct btree *b = container_of(bk, struct btree, keys);
unsigned int i, stale;
char buf[80];
if (!KEY_PTRS(k) ||
bch_extent_invalid(bk, k))
return true;
for (i = 0; i < KEY_PTRS(k); i++)
if (!ptr_available(b->c, k, i))
return true;
for (i = 0; i < KEY_PTRS(k); i++) {
stale = ptr_stale(b->c, k, i);
if (stale && KEY_DIRTY(k)) {
bch_extent_to_text(buf, sizeof(buf), k);
pr_info("stale dirty pointer, stale %u, key: %s\n",
stale, buf);
}
btree_bug_on(stale > BUCKET_GC_GEN_MAX, b,
"key too stale: %i, need_gc %u",
stale, b->c->need_gc);
if (stale)
return true;
if (expensive_debug_checks(b->c) &&
bch_extent_bad_expensive(b, k, i))
return true;
}
return false;
}
static uint64_t merge_chksums(struct bkey *l, struct bkey *r)
{
return (l->ptr[KEY_PTRS(l)] + r->ptr[KEY_PTRS(r)]) &
~((uint64_t)1 << 63);
}
static bool bch_extent_merge(struct btree_keys *bk,
struct bkey *l,
struct bkey *r)
{
struct btree *b = container_of(bk, struct btree, keys);
unsigned int i;
if (key_merging_disabled(b->c))
return false;
for (i = 0; i < KEY_PTRS(l); i++)
if (l->ptr[i] + MAKE_PTR(0, KEY_SIZE(l), 0) != r->ptr[i] ||
PTR_BUCKET_NR(b->c, l, i) != PTR_BUCKET_NR(b->c, r, i))
return false;
/* Keys with no pointers aren't restricted to one bucket and could
* overflow KEY_SIZE
*/
if (KEY_SIZE(l) + KEY_SIZE(r) > USHRT_MAX) {
SET_KEY_OFFSET(l, KEY_OFFSET(l) + USHRT_MAX - KEY_SIZE(l));
SET_KEY_SIZE(l, USHRT_MAX);
bch_cut_front(l, r);
return false;
}
if (KEY_CSUM(l)) {
if (KEY_CSUM(r))
l->ptr[KEY_PTRS(l)] = merge_chksums(l, r);
else
SET_KEY_CSUM(l, 0);
}
SET_KEY_OFFSET(l, KEY_OFFSET(l) + KEY_SIZE(r));
SET_KEY_SIZE(l, KEY_SIZE(l) + KEY_SIZE(r));
return true;
}
const struct btree_keys_ops bch_extent_keys_ops = {
.sort_cmp = new_bch_extent_sort_cmp,
.sort_fixup = bch_extent_sort_fixup,
.insert_fixup = bch_extent_insert_fixup,
.key_invalid = bch_extent_invalid,
.key_bad = bch_extent_bad,
.key_merge = bch_extent_merge,
.key_to_text = bch_extent_to_text,
.key_dump = bch_bkey_dump,
.is_extents = true,
};
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