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Commit a34a8bfd authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Refactor journalling flow control 



Making things less asynchronous that don't need to be - bch_journal()
only has to block when the journal or journal entry is full, which is
emphatically not a fast path. So make it a normal function that just
returns when it finishes, to make the code and control flow easier to
follow.

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent cdd972b1

drivers/md/bcache/btree.c

+0 −3
Original line number Diff line number Diff line
@@ -2164,9 +2164,6 @@ int bch_btree_insert(struct btree_op *op, struct cache_set *c, 
		}

	}



	if (op->journal)

		atomic_dec_bug(op->journal);

	op->journal = NULL;

	return ret;

}

drivers/md/bcache/closure.h

+1 −1
Original line number Diff line number Diff line
@@ -642,7 +642,7 @@ do { \ 
#define continue_at_nobarrier(_cl, _fn, _wq)				\

do {									\

	set_closure_fn(_cl, _fn, _wq);					\

	closure_queue(cl);						\

	closure_queue(_cl);						\

	return;								\

} while (0)

drivers/md/bcache/journal.c

+100 −113
Original line number Diff line number Diff line
@@ -318,7 +318,6 @@ int bch_journal_replay(struct cache_set *s, struct list_head *list, 
			bch_keylist_push(&op->keys);



			op->journal = i->pin;

			atomic_inc(op->journal);



			ret = bch_btree_insert(op, s, &op->keys);

			if (ret)
@@ -357,48 +356,35 @@ static void btree_flush_write(struct cache_set *c) 
	 * Try to find the btree node with that references the oldest journal

	 * entry, best is our current candidate and is locked if non NULL:

	 */

	struct btree *b, *best = NULL;

	unsigned iter;



	for_each_cached_btree(b, c, iter) {

		if (!down_write_trylock(&b->lock))

			continue;



		if (!btree_node_dirty(b) ||

		    !btree_current_write(b)->journal) {

			rw_unlock(true, b);

			continue;

		}

	struct btree *b, *best;

	unsigned i;

retry:

	best = NULL;



	for_each_cached_btree(b, c, i)

		if (btree_current_write(b)->journal) {

			if (!best)

				best = b;

			else if (journal_pin_cmp(c,

						 btree_current_write(best),

						 btree_current_write(b))) {

			rw_unlock(true, best);

				best = b;

		} else

			rw_unlock(true, b);

			}

		}



	if (best)

		goto out;

	b = best;

	if (b) {

		rw_lock(true, b, b->level);



	/* We can't find the best btree node, just pick the first */

	list_for_each_entry(b, &c->btree_cache, list)

		if (!b->level && btree_node_dirty(b)) {

			best = b;

			rw_lock(true, best, best->level);

			goto found;

		if (!btree_current_write(b)->journal) {

			rw_unlock(true, b);

			/* We raced */

			goto retry;

		}



out:

	if (!best)

		return;

found:

	if (btree_node_dirty(best))

		bch_btree_node_write(best, NULL);

	rw_unlock(true, best);

		bch_btree_node_write(b, NULL);

		rw_unlock(true, b);

	}

}



#define last_seq(j)	((j)->seq - fifo_used(&(j)->pin) + 1)
@@ -494,7 +480,7 @@ static void journal_reclaim(struct cache_set *c) 
		do_journal_discard(ca);



	if (c->journal.blocks_free)

		return;

		goto out;



	/*

	 * Allocate:
@@ -520,7 +506,7 @@ static void journal_reclaim(struct cache_set *c) 


	if (n)

		c->journal.blocks_free = c->sb.bucket_size >> c->block_bits;



out:

	if (!journal_full(&c->journal))

		__closure_wake_up(&c->journal.wait);

}
@@ -659,7 +645,7 @@ static void journal_write(struct closure *cl) 
	journal_write_unlocked(cl);

}



static void __journal_try_write(struct cache_set *c, bool noflush)

static void journal_try_write(struct cache_set *c)

	__releases(c->journal.lock)

{

	struct closure *cl = &c->journal.io;
@@ -667,29 +653,59 @@ static void __journal_try_write(struct cache_set *c, bool noflush) 


	w->need_write = true;



	if (!closure_trylock(cl, &c->cl))

		spin_unlock(&c->journal.lock);

	else if (noflush && journal_full(&c->journal)) {

		spin_unlock(&c->journal.lock);

		continue_at(cl, journal_write, system_wq);

	} else

	if (closure_trylock(cl, &c->cl))

		journal_write_unlocked(cl);

	else

		spin_unlock(&c->journal.lock);

}



#define journal_try_write(c)	__journal_try_write(c, false)



void bch_journal_meta(struct cache_set *c, struct closure *cl)

static struct journal_write *journal_wait_for_write(struct cache_set *c,

						    unsigned nkeys)

{

	struct journal_write *w;

	size_t sectors;

	struct closure cl;



	closure_init_stack(&cl);



	if (CACHE_SYNC(&c->sb)) {

	spin_lock(&c->journal.lock);

		w = c->journal.cur;



		if (cl)

			BUG_ON(!closure_wait(&w->wait, cl));

	while (1) {

		struct journal_write *w = c->journal.cur;



		sectors = __set_blocks(w->data, w->data->keys + nkeys,

				       c) * c->sb.block_size;



		if (sectors <= min_t(size_t,

				     c->journal.blocks_free * c->sb.block_size,

				     PAGE_SECTORS << JSET_BITS))

			return w;



		/* XXX: tracepoint */

		if (!journal_full(&c->journal)) {

			trace_bcache_journal_entry_full(c);



			/*

			 * XXX: If we were inserting so many keys that they

			 * won't fit in an _empty_ journal write, we'll

			 * deadlock. For now, handle this in

			 * bch_keylist_realloc() - but something to think about.

			 */

			BUG_ON(!w->data->keys);



			closure_wait(&w->wait, &cl);

			journal_try_write(c); /* unlocks */

		} else {

			trace_bcache_journal_full(c);



		__journal_try_write(c, true);

			closure_wait(&c->journal.wait, &cl);

			journal_reclaim(c);

			spin_unlock(&c->journal.lock);



			btree_flush_write(c);

		}



		closure_sync(&cl);

		spin_lock(&c->journal.lock);

	}

}
@@ -708,68 +724,26 @@ static void journal_write_work(struct work_struct *work) 
 * bch_journal() hands those same keys off to btree_insert_async()

 */



void bch_journal(struct closure *cl)

atomic_t *bch_journal(struct cache_set *c,

		      struct keylist *keys,

		      struct closure *parent)

{

	struct btree_op *op = container_of(cl, struct btree_op, cl);

	struct cache_set *c = op->c;

	struct journal_write *w;

	size_t sectors, nkeys;



	if (op->type != BTREE_INSERT ||

	    !CACHE_SYNC(&c->sb))

		goto out;



	/*

	 * If we're looping because we errored, might already be waiting on

	 * another journal write:

	 */

	while (atomic_read(&cl->parent->remaining) & CLOSURE_WAITING)

		closure_sync(cl->parent);

	atomic_t *ret;



	spin_lock(&c->journal.lock);

	if (!CACHE_SYNC(&c->sb))

		return NULL;



	if (journal_full(&c->journal)) {

		trace_bcache_journal_full(c);

	w = journal_wait_for_write(c, bch_keylist_nkeys(keys));



		closure_wait(&c->journal.wait, cl);

	memcpy(end(w->data), keys->keys, bch_keylist_bytes(keys));

	w->data->keys += bch_keylist_nkeys(keys);



		journal_reclaim(c);

		spin_unlock(&c->journal.lock);

	ret = &fifo_back(&c->journal.pin);

	atomic_inc(ret);



		btree_flush_write(c);

		continue_at(cl, bch_journal, bcache_wq);

	}



	w = c->journal.cur;

	nkeys = w->data->keys + bch_keylist_nkeys(&op->keys);

	sectors = __set_blocks(w->data, nkeys, c) * c->sb.block_size;



	if (sectors > min_t(size_t,

			    c->journal.blocks_free * c->sb.block_size,

			    PAGE_SECTORS << JSET_BITS)) {

		trace_bcache_journal_entry_full(c);



		/*

		 * XXX: If we were inserting so many keys that they won't fit in

		 * an _empty_ journal write, we'll deadlock. For now, handle

		 * this in bch_keylist_realloc() - but something to think about.

		 */

		BUG_ON(!w->data->keys);



		BUG_ON(!closure_wait(&w->wait, cl));



		journal_try_write(c);

		continue_at(cl, bch_journal, bcache_wq);

	}



	memcpy(end(w->data), op->keys.keys, bch_keylist_bytes(&op->keys));

	w->data->keys += bch_keylist_nkeys(&op->keys);



	op->journal = &fifo_back(&c->journal.pin);

	atomic_inc(op->journal);



	if (op->flush_journal) {

		closure_wait(&w->wait, cl->parent);

	if (parent) {

		closure_wait(&w->wait, parent);

		journal_try_write(c);

	} else if (!w->need_write) {

		schedule_delayed_work(&c->journal.work,
@@ -778,8 +752,21 @@ void bch_journal(struct closure *cl) 
	} else {

		spin_unlock(&c->journal.lock);

	}

out:

	bch_btree_insert_async(cl);





	return ret;

}



void bch_journal_meta(struct cache_set *c, struct closure *cl)

{

	struct keylist keys;

	atomic_t *ref;



	bch_keylist_init(&keys);



	ref = bch_journal(c, &keys, cl);

	if (ref)

		atomic_dec_bug(ref);

}



void bch_journal_free(struct cache_set *c)

drivers/md/bcache/journal.h

+2 −1
Original line number Diff line number Diff line
@@ -200,8 +200,9 @@ struct journal_device { 
struct closure;

struct cache_set;

struct btree_op;

struct keylist;



void bch_journal(struct closure *);

atomic_t *bch_journal(struct cache_set *, struct keylist *, struct closure *);

void bch_journal_next(struct journal *);

void bch_journal_mark(struct cache_set *, struct list_head *);

void bch_journal_meta(struct cache_set *, struct closure *);

drivers/md/bcache/movinggc.c

+1 −1
Original line number Diff line number Diff line
@@ -110,7 +110,7 @@ static void write_moving(struct closure *cl) 
		bkey_copy(&s->op.replace, &io->w->key);



		closure_init(&s->op.cl, cl);

		bch_insert_data(&s->op.cl);

		bch_data_insert(&s->op.cl);

	}



	continue_at(cl, write_moving_finish, bch_gc_wq);