bcache: A block layer cache

Does writethrough and writeback caching, handles unclean shutdown, and
has a bunch of other nifty features motivated by real world usage.

See the wiki at http://bcache.evilpiepirate.org for more.

Signed-off-by: Kent Overstreet <koverstreet@google.com>

1 files changed, 563 insertions, 0 deletions

diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
new file mode 100644
index 0000000..4b37ef2
--- /dev/null
+++ b/drivers/md/bcache/debug.c
@@ -0,0 +1,563 @@
+/*
+ * Assorted bcache debug code
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+#include <linux/console.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+
+static struct dentry *debug;
+
+const char *bch_ptr_status(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)
+				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 "";
+}
+
+struct keyprint_hack bch_pkey(const struct bkey *k)
+{
+	unsigned i = 0;
+	struct keyprint_hack r;
+	char *out = r.s, *end = r.s + KEYHACK_SIZE;
+
+#define p(...)	(out += scnprintf(out, end - out, __VA_ARGS__))
+
+	p("%llu:%llu len %llu -> [", KEY_INODE(k), KEY_OFFSET(k), KEY_SIZE(k));
+
+	if (KEY_PTRS(k))
+		while (1) {
+			p("%llu:%llu gen %llu",
+			  PTR_DEV(k, i), PTR_OFFSET(k, i), PTR_GEN(k, i));
+
+			if (++i == KEY_PTRS(k))
+				break;
+
+			p(", ");
+		}
+
+	p("]");
+
+	if (KEY_DIRTY(k))
+		p(" dirty");
+	if (KEY_CSUM(k))
+		p(" cs%llu %llx", KEY_CSUM(k), k->ptr[1]);
+#undef p
+	return r;
+}
+
+struct keyprint_hack bch_pbtree(const struct btree *b)
+{
+	struct keyprint_hack r;
+
+	snprintf(r.s, 40, "%li level %i/%i", PTR_BUCKET_NR(b->c, &b->key, 0),
+		 b->level, b->c->root ? b->c->root->level : -1);
+	return r;
+}
+
+#if defined(CONFIG_BCACHE_DEBUG) || defined(CONFIG_BCACHE_EDEBUG)
+
+static bool skipped_backwards(struct btree *b, struct bkey *k)
+{
+	return bkey_cmp(k, (!b->level)
+			? &START_KEY(bkey_next(k))
+			: bkey_next(k)) > 0;
+}
+
+static void dump_bset(struct btree *b, struct bset *i)
+{
+	struct bkey *k;
+	unsigned j;
+
+	for (k = i->start; k < end(i); k = bkey_next(k)) {
+		printk(KERN_ERR "block %zu key %zi/%u: %s", index(i, b),
+		       (uint64_t *) k - i->d, i->keys, pkey(k));
+
+		for (j = 0; j < KEY_PTRS(k); j++) {
+			size_t n = PTR_BUCKET_NR(b->c, k, j);
+			printk(" bucket %zu", n);
+
+			if (n >= b->c->sb.first_bucket && n < b->c->sb.nbuckets)
+				printk(" prio %i",
+				       PTR_BUCKET(b->c, k, j)->prio);
+		}
+
+		printk(" %s\n", bch_ptr_status(b->c, k));
+
+		if (bkey_next(k) < end(i) &&
+		    skipped_backwards(b, k))
+			printk(KERN_ERR "Key skipped backwards\n");
+	}
+}
+
+#endif
+
+#ifdef CONFIG_BCACHE_DEBUG
+
+void bch_btree_verify(struct btree *b, struct bset *new)
+{
+	struct btree *v = b->c->verify_data;
+	struct closure cl;
+	closure_init_stack(&cl);
+
+	if (!b->c->verify)
+		return;
+
+	closure_wait_event(&b->io.wait, &cl,
+			   atomic_read(&b->io.cl.remaining) == -1);
+
+	mutex_lock(&b->c->verify_lock);
+
+	bkey_copy(&v->key, &b->key);
+	v->written = 0;
+	v->level = b->level;
+
+	bch_btree_read(v);
+	closure_wait_event(&v->io.wait, &cl,
+			   atomic_read(&b->io.cl.remaining) == -1);
+
+	if (new->keys != v->sets[0].data->keys ||
+	    memcmp(new->start,
+		   v->sets[0].data->start,
+		   (void *) end(new) - (void *) new->start)) {
+		unsigned i, j;
+
+		console_lock();
+
+		printk(KERN_ERR "*** original memory node:\n");
+		for (i = 0; i <= b->nsets; i++)
+			dump_bset(b, b->sets[i].data);
+
+		printk(KERN_ERR "*** sorted memory node:\n");
+		dump_bset(b, new);
+
+		printk(KERN_ERR "*** on disk node:\n");
+		dump_bset(v, v->sets[0].data);
+
+		for (j = 0; j < new->keys; j++)
+			if (new->d[j] != v->sets[0].data->d[j])
+				break;
+
+		console_unlock();
+		panic("verify failed at %u\n", j);
+	}
+
+	mutex_unlock(&b->c->verify_lock);
+}
+
+static void data_verify_endio(struct bio *bio, int error)
+{
+	struct closure *cl = bio->bi_private;
+	closure_put(cl);
+}
+
+void bch_data_verify(struct search *s)
+{
+	char name[BDEVNAME_SIZE];
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+	struct closure *cl = &s->cl;
+	struct bio *check;
+	struct bio_vec *bv;
+	int i;
+
+	if (!s->unaligned_bvec)
+		bio_for_each_segment(bv, s->orig_bio, i)
+			bv->bv_offset = 0, bv->bv_len = PAGE_SIZE;
+
+	check = bio_clone(s->orig_bio, GFP_NOIO);
+	if (!check)
+		return;
+
+	if (bio_alloc_pages(check, GFP_NOIO))
+		goto out_put;
+
+	check->bi_rw		= READ_SYNC;
+	check->bi_private	= cl;
+	check->bi_end_io	= data_verify_endio;
+
+	closure_bio_submit(check, cl, &dc->disk);
+	closure_sync(cl);
+
+	bio_for_each_segment(bv, s->orig_bio, i) {
+		void *p1 = kmap(bv->bv_page);
+		void *p2 = kmap(check->bi_io_vec[i].bv_page);
+
+		if (memcmp(p1 + bv->bv_offset,
+			   p2 + bv->bv_offset,
+			   bv->bv_len))
+			printk(KERN_ERR "bcache (%s): verify failed"
+			       " at sector %llu\n",
+			       bdevname(dc->bdev, name),
+			       (uint64_t) s->orig_bio->bi_sector);
+
+		kunmap(bv->bv_page);
+		kunmap(check->bi_io_vec[i].bv_page);
+	}
+
+	__bio_for_each_segment(bv, check, i, 0)
+		__free_page(bv->bv_page);
+out_put:
+	bio_put(check);
+}
+
+#endif
+
+#ifdef CONFIG_BCACHE_EDEBUG
+
+unsigned bch_count_data(struct btree *b)
+{
+	unsigned ret = 0;
+	struct btree_iter iter;
+	struct bkey *k;
+
+	if (!b->level)
+		for_each_key(b, k, &iter)
+			ret += KEY_SIZE(k);
+	return ret;
+}
+
+static void vdump_bucket_and_panic(struct btree *b, const char *fmt,
+				   va_list args)
+{
+	unsigned i;
+
+	console_lock();
+
+	for (i = 0; i <= b->nsets; i++)
+		dump_bset(b, b->sets[i].data);
+
+	vprintk(fmt, args);
+
+	console_unlock();
+
+	panic("at %s\n", pbtree(b));
+}
+
+void bch_check_key_order_msg(struct btree *b, struct bset *i,
+			     const char *fmt, ...)
+{
+	struct bkey *k;
+
+	if (!i->keys)
+		return;
+
+	for (k = i->start; bkey_next(k) < end(i); k = bkey_next(k))
+		if (skipped_backwards(b, k)) {
+			va_list args;
+			va_start(args, fmt);
+
+			vdump_bucket_and_panic(b, fmt, args);
+			va_end(args);
+		}
+}
+
+void bch_check_keys(struct btree *b, const char *fmt, ...)
+{
+	va_list args;
+	struct bkey *k, *p = NULL;
+	struct btree_iter iter;
+
+	if (b->level)
+		return;
+
+	for_each_key(b, k, &iter) {
+		if (p && bkey_cmp(&START_KEY(p), &START_KEY(k)) > 0) {
+			printk(KERN_ERR "Keys out of order:\n");
+			goto bug;
+		}
+
+		if (bch_ptr_invalid(b, k))
+			continue;
+
+		if (p && bkey_cmp(p, &START_KEY(k)) > 0) {
+			printk(KERN_ERR "Overlapping keys:\n");
+			goto bug;
+		}
+		p = k;
+	}
+	return;
+bug:
+	va_start(args, fmt);
+	vdump_bucket_and_panic(b, fmt, args);
+	va_end(args);
+}
+
+#endif
+
+#ifdef CONFIG_DEBUG_FS
+
+/* XXX: cache set refcounting */
+
+struct dump_iterator {
+	char			buf[PAGE_SIZE];
+	size_t			bytes;
+	struct cache_set	*c;
+	struct keybuf		keys;
+};
+
+static bool dump_pred(struct keybuf *buf, struct bkey *k)
+{
+	return true;
+}
+
+static ssize_t bch_dump_read(struct file *file, char __user *buf,
+			     size_t size, loff_t *ppos)
+{
+	struct dump_iterator *i = file->private_data;
+	ssize_t ret = 0;
+
+	while (size) {
+		struct keybuf_key *w;
+		unsigned bytes = min(i->bytes, size);
+
+		int err = copy_to_user(buf, i->buf, bytes);
+		if (err)
+			return err;
+
+		ret	 += bytes;
+		buf	 += bytes;
+		size	 -= bytes;
+		i->bytes -= bytes;
+		memmove(i->buf, i->buf + bytes, i->bytes);
+
+		if (i->bytes)
+			break;
+
+		w = bch_keybuf_next_rescan(i->c, &i->keys, &MAX_KEY);
+		if (!w)
+			break;
+
+		i->bytes = snprintf(i->buf, PAGE_SIZE, "%s\n", pkey(&w->key));
+		bch_keybuf_del(&i->keys, w);
+	}
+
+	return ret;
+}
+
+static int bch_dump_open(struct inode *inode, struct file *file)
+{
+	struct cache_set *c = inode->i_private;
+	struct dump_iterator *i;
+
+	i = kzalloc(sizeof(struct dump_iterator), GFP_KERNEL);
+	if (!i)
+		return -ENOMEM;
+
+	file->private_data = i;
+	i->c = c;
+	bch_keybuf_init(&i->keys, dump_pred);
+	i->keys.last_scanned = KEY(0, 0, 0);
+
+	return 0;
+}
+
+static int bch_dump_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static const struct file_operations cache_set_debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch_dump_open,
+	.read		= bch_dump_read,
+	.release	= bch_dump_release
+};
+
+void bch_debug_init_cache_set(struct cache_set *c)
+{
+	if (!IS_ERR_OR_NULL(debug)) {
+		char name[50];
+		snprintf(name, 50, "bcache-%pU", c->sb.set_uuid);
+
+		c->debug = debugfs_create_file(name, 0400, debug, c,
+					       &cache_set_debug_ops);
+	}
+}
+
+#endif
+
+#ifdef CONFIG_BCACHE_DEBUG
+static ssize_t btree_fuzz(struct kobject *k, struct kobj_attribute *a,
+			  const char *buffer, size_t size)
+{
+	void dump(struct btree *b)
+	{
+		struct bset *i;
+
+		for (i = b->sets[0].data;
+		     index(i, b) < btree_blocks(b) &&
+		     i->seq == b->sets[0].data->seq;
+		     i = ((void *) i) + set_blocks(i, b->c) * block_bytes(b->c))
+			dump_bset(b, i);
+	}
+
+	struct cache_sb *sb;
+	struct cache_set *c;
+	struct btree *all[3], *b, *fill, *orig;
+	int j;
+
+	struct btree_op op;
+	bch_btree_op_init_stack(&op);
+
+	sb = kzalloc(sizeof(struct cache_sb), GFP_KERNEL);
+	if (!sb)
+		return -ENOMEM;
+
+	sb->bucket_size = 128;
+	sb->block_size = 4;
+
+	c = bch_cache_set_alloc(sb);
+	if (!c)
+		return -ENOMEM;
+
+	for (j = 0; j < 3; j++) {
+		BUG_ON(list_empty(&c->btree_cache));
+		all[j] = list_first_entry(&c->btree_cache, struct btree, list);
+		list_del_init(&all[j]->list);
+
+		all[j]->key = KEY(0, 0, c->sb.bucket_size);
+		bkey_copy_key(&all[j]->key, &MAX_KEY);
+	}
+
+	b = all[0];
+	fill = all[1];
+	orig = all[2];
+
+	while (1) {
+		for (j = 0; j < 3; j++)
+			all[j]->written = all[j]->nsets = 0;
+
+		bch_bset_init_next(b);
+
+		while (1) {
+			struct bset *i = write_block(b);
+			struct bkey *k = op.keys.top;
+			unsigned rand;
+
+			bkey_init(k);
+			rand = get_random_int();
+
+			op.type = rand & 1
+				? BTREE_INSERT
+				: BTREE_REPLACE;
+			rand >>= 1;
+
+			SET_KEY_SIZE(k, bucket_remainder(c, rand));
+			rand >>= c->bucket_bits;
+			rand &= 1024 * 512 - 1;
+			rand += c->sb.bucket_size;
+			SET_KEY_OFFSET(k, rand);
+#if 0
+			SET_KEY_PTRS(k, 1);
+#endif
+			bch_keylist_push(&op.keys);
+			bch_btree_insert_keys(b, &op);
+
+			if (should_split(b) ||
+			    set_blocks(i, b->c) !=
+			    __set_blocks(i, i->keys + 15, b->c)) {
+				i->csum = csum_set(i);
+
+				memcpy(write_block(fill),
+				       i, set_bytes(i));
+
+				b->written += set_blocks(i, b->c);
+				fill->written = b->written;
+				if (b->written == btree_blocks(b))
+					break;
+
+				bch_btree_sort_lazy(b);
+				bch_bset_init_next(b);
+			}
+		}
+
+		memcpy(orig->sets[0].data,
+		       fill->sets[0].data,
+		       btree_bytes(c));
+
+		bch_btree_sort(b);
+		fill->written = 0;
+		bch_btree_read_done(&fill->io.cl);
+
+		if (b->sets[0].data->keys != fill->sets[0].data->keys ||
+		    memcmp(b->sets[0].data->start,
+			   fill->sets[0].data->start,
+			   b->sets[0].data->keys * sizeof(uint64_t))) {
+			struct bset *i = b->sets[0].data;
+			struct bkey *k, *l;
+
+			for (k = i->start,
+			     l = fill->sets[0].data->start;
+			     k < end(i);
+			     k = bkey_next(k), l = bkey_next(l))
+				if (bkey_cmp(k, l) ||
+				    KEY_SIZE(k) != KEY_SIZE(l))
+					pr_err("key %zi differs: %s "
+					       "!= %s", (uint64_t *) k - i->d,
+					       pkey(k), pkey(l));
+
+			for (j = 0; j < 3; j++) {
+				pr_err("**** Set %i ****", j);
+				dump(all[j]);
+			}
+			panic("\n");
+		}
+
+		pr_info("fuzz complete: %i keys", b->sets[0].data->keys);
+	}
+}
+
+kobj_attribute_write(fuzz, btree_fuzz);
+#endif
+
+void bch_debug_exit(void)
+{
+	if (!IS_ERR_OR_NULL(debug))
+		debugfs_remove_recursive(debug);
+}
+
+int __init bch_debug_init(struct kobject *kobj)
+{
+	int ret = 0;
+#ifdef CONFIG_BCACHE_DEBUG
+	ret = sysfs_create_file(kobj, &ksysfs_fuzz.attr);
+	if (ret)
+		return ret;
+#endif
+
+	debug = debugfs_create_dir("bcache", NULL);
+	return ret;
+}