Commit 249a5f6d authored by Coly Li's avatar Coly Li Committed by Jens Axboe
Browse files

bcache: Revert "bcache: fix high CPU occupancy during journal" 



This reverts commit c4dc2497.

This patch enlarges a race between normal btree flush code path and
flush_btree_write(), which causes deadlock when journal space is
exhausted. Reverts this patch makes the race window from 128 btree
nodes to only 1 btree nodes.

Fixes: c4dc2497 ("bcache: fix high CPU occupancy during journal")
Signed-off-by: default avatarColy Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Cc: Tang Junhui <tang.junhui.linux@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent ba82c1ac

drivers/md/bcache/bcache.h

+0 −2
Original line number Diff line number Diff line
@@ -726,8 +726,6 @@ struct cache_set { 


#define BUCKET_HASH_BITS	12

	struct hlist_head	bucket_hash[1 << BUCKET_HASH_BITS];



	DECLARE_HEAP(struct btree *, flush_btree);

};



struct bbio {

drivers/md/bcache/journal.c

+15 −32
Original line number Diff line number Diff line
@@ -416,12 +416,6 @@ err: 
}



/* Journalling */

#define journal_max_cmp(l, r) \

	(fifo_idx(&c->journal.pin, btree_current_write(l)->journal) < \

	 fifo_idx(&(c)->journal.pin, btree_current_write(r)->journal))

#define journal_min_cmp(l, r) \

	(fifo_idx(&c->journal.pin, btree_current_write(l)->journal) > \

	 fifo_idx(&(c)->journal.pin, btree_current_write(r)->journal))



static void btree_flush_write(struct cache_set *c)

{
@@ -429,35 +423,25 @@ 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;

	int i;

	struct btree *b, *best;

	unsigned int i;



	atomic_long_inc(&c->flush_write);



retry:

	spin_lock(&c->journal.lock);

	if (heap_empty(&c->flush_btree)) {

	best = NULL;



	for_each_cached_btree(b, c, i)

		if (btree_current_write(b)->journal) {

				if (!heap_full(&c->flush_btree))

					heap_add(&c->flush_btree, b,

						 journal_max_cmp);

				else if (journal_max_cmp(b,

					 heap_peek(&c->flush_btree))) {

					c->flush_btree.data[0] = b;

					heap_sift(&c->flush_btree, 0,

						  journal_max_cmp);

			if (!best)

				best = b;

			else if (journal_pin_cmp(c,

					btree_current_write(best)->journal,

					btree_current_write(b)->journal)) {

				best = b;

			}

		}



		for (i = c->flush_btree.used / 2 - 1; i >= 0; --i)

			heap_sift(&c->flush_btree, i, journal_min_cmp);

	}



	b = NULL;

	heap_pop(&c->flush_btree, b, journal_min_cmp);

	spin_unlock(&c->journal.lock);



	b = best;

	if (b) {

		mutex_lock(&b->write_lock);

		if (!btree_current_write(b)->journal) {
@@ -898,8 +882,7 @@ int bch_journal_alloc(struct cache_set *c) 
	j->w[0].c = c;

	j->w[1].c = c;



	if (!(init_heap(&c->flush_btree, 128, GFP_KERNEL)) ||

	    !(init_fifo(&j->pin, JOURNAL_PIN, GFP_KERNEL)) ||

	if (!(init_fifo(&j->pin, JOURNAL_PIN, GFP_KERNEL)) ||

	    !(j->w[0].data = (void *) __get_free_pages(GFP_KERNEL, JSET_BITS)) ||

	    !(j->w[1].data = (void *) __get_free_pages(GFP_KERNEL, JSET_BITS)))

		return -ENOMEM;

drivers/md/bcache/util.h

+0 −2
Original line number Diff line number Diff line
@@ -113,8 +113,6 @@ do { \ 


#define heap_full(h)	((h)->used == (h)->size)



#define heap_empty(h)	((h)->used == 0)



#define DECLARE_FIFO(type, name)					\

	struct {							\

		size_t front, back, size, mask;				\

CRA Git | Maintained and supported by SUSTech CRA and CCSE