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authorKent Overstreet <kmo@daterainc.com>2013-12-21 05:22:05 +0400
committerKent Overstreet <kmo@daterainc.com>2014-01-09 01:05:12 +0400
commit65d45231b56efb3db51eb441e2c68f8252ecdd12 (patch)
treeb862e6fa72d076373c79841b555ef525d3b0f41b /drivers/md/bcache/extents.c
parentee811287c9f241641899788cbfc9d70ed96ba3a5 (diff)
downloadlinux-65d45231b56efb3db51eb441e2c68f8252ecdd12.tar.xz
bcache: Abstract out stuff needed for sorting
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Diffstat (limited to 'drivers/md/bcache/extents.c')
-rw-r--r--drivers/md/bcache/extents.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c
new file mode 100644
index 000000000000..8fe6aaece41d
--- /dev/null
+++ b/drivers/md/bcache/extents.c
@@ -0,0 +1,354 @@
+/*
+ * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
+ *
+ * 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/bcache.txt.
+ */
+
+#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->data[--iter->used];
+}
+
+static bool bch_key_sort_cmp(struct btree_iter_set l,
+ 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 i;
+
+ for (i = 0; i < KEY_PTRS(k); i++)
+ if (ptr_available(c, k, i)) {
+ struct cache *ca = PTR_CACHE(c, k, i);
+ 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->sb.bucket_size ||
+ bucket < ca->sb.first_bucket ||
+ bucket >= ca->sb.nbuckets)
+ return true;
+ }
+
+ return false;
+}
+
+/* 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_bkey_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 *b, const struct bkey *k)
+{
+ return __bch_btree_ptr_invalid(b->c, k);
+}
+
+static bool btree_ptr_bad_expensive(struct btree *b, const struct bkey *k)
+{
+ unsigned 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_bkey_to_text(buf, sizeof(buf), k);
+ btree_bug(b,
+"inconsistent btree pointer %s: bucket %li pin %i prio %i gen %i last_gc %i mark %llu gc_gen %i",
+ buf, PTR_BUCKET_NR(b->c, k, i), atomic_read(&g->pin),
+ g->prio, g->gen, g->last_gc, GC_MARK(g), g->gc_gen);
+ return true;
+}
+
+static bool bch_btree_ptr_bad(struct btree *b, const struct bkey *k)
+{
+ unsigned i;
+
+ if (!bkey_cmp(k, &ZERO_KEY) ||
+ !KEY_PTRS(k) ||
+ bch_ptr_invalid(b, 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;
+}
+
+const struct btree_keys_ops bch_btree_keys_ops = {
+ .sort_cmp = bch_key_sort_cmp,
+ .key_invalid = bch_btree_ptr_invalid,
+ .key_bad = bch_btree_ptr_bad,
+};
+
+/* 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 bch_extent_sort_cmp(struct btree_iter_set l,
+ 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 struct bkey *bch_extent_sort_fixup(struct btree_iter *iter,
+ struct bkey *tmp)
+{
+ while (iter->used > 1) {
+ struct btree_iter_set *top = iter->data, *i = top + 1;
+
+ if (iter->used > 2 &&
+ bch_extent_sort_cmp(i[0], i[1]))
+ i++;
+
+ if (bkey_cmp(top->k, &START_KEY(i->k)) <= 0)
+ break;
+
+ if (!KEY_SIZE(i->k)) {
+ sort_key_next(iter, i);
+ heap_sift(iter, i - top, bch_extent_sort_cmp);
+ 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);
+
+ heap_sift(iter, i - top, bch_extent_sort_cmp);
+ } 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);
+ heap_sift(iter, 0, bch_extent_sort_cmp);
+
+ return tmp;
+ } else {
+ bch_cut_back(&START_KEY(i->k), top->k);
+ }
+ }
+ }
+
+ return NULL;
+}
+
+static bool bch_extent_invalid(struct btree *b, 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(b->c, k))
+ goto bad;
+
+ return false;
+bad:
+ bch_bkey_to_text(buf, sizeof(buf), k);
+ cache_bug(b->c, "spotted extent %s: %s", buf, bch_ptr_status(b->c, k));
+ return true;
+}
+
+static bool bch_extent_bad_expensive(struct btree *b, const struct bkey *k,
+ unsigned 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_DIRTY &&
+ KEY_DIRTY(k)) ||
+ GC_MARK(g) == GC_MARK_METADATA))
+ 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_bkey_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 gc_gen %i",
+ buf, PTR_BUCKET_NR(b->c, k, ptr), atomic_read(&g->pin),
+ g->prio, g->gen, g->last_gc, GC_MARK(g), g->gc_gen);
+ return true;
+}
+
+static bool bch_extent_bad(struct btree *b, const struct bkey *k)
+{
+ struct bucket *g;
+ unsigned i, stale;
+
+ if (!KEY_PTRS(k) ||
+ bch_extent_invalid(b, k))
+ return true;
+
+ for (i = 0; i < KEY_PTRS(k); i++)
+ if (!ptr_available(b->c, k, i))
+ return true;
+
+ if (!expensive_debug_checks(b->c) && KEY_DIRTY(k))
+ return false;
+
+ for (i = 0; i < KEY_PTRS(k); i++) {
+ g = PTR_BUCKET(b->c, k, i);
+ stale = ptr_stale(b->c, k, i);
+
+ btree_bug_on(stale > 96, b,
+ "key too stale: %i, need_gc %u",
+ stale, b->c->need_gc);
+
+ btree_bug_on(stale && KEY_DIRTY(k) && KEY_SIZE(k),
+ b, "stale dirty pointer");
+
+ 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 *b, struct bkey *l, struct bkey *r)
+{
+ unsigned i;
+
+ if (key_merging_disabled(b->c))
+ return false;
+
+ if (KEY_PTRS(l) != KEY_PTRS(r) ||
+ KEY_DIRTY(l) != KEY_DIRTY(r) ||
+ bkey_cmp(l, &START_KEY(r)))
+ return false;
+
+ for (i = 0; i < KEY_PTRS(l); i++)
+ if (l->ptr[i] + 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 = bch_extent_sort_cmp,
+ .sort_fixup = bch_extent_sort_fixup,
+ .key_invalid = bch_extent_invalid,
+ .key_bad = bch_extent_bad,
+ .key_merge = bch_extent_merge,
+ .is_extents = true,
+};