From: Coly Li <colyli@xxxxxxx>
commit 249a5f6da57c28a903c75d81505d58ec8c10030d upstream.
This reverts commit c4dc2497d50d9c6fb16aa0d07b6a14f3b2adb1e0.
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: c4dc2497d50d ("bcache: fix high CPU occupancy during journal")
Signed-off-by: Coly Li <colyli@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: Tang Junhui <tang.junhui.linux@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/bcache/bcache.h | 2 -
drivers/md/bcache/journal.c | 47 ++++++++++++++------------------------------
drivers/md/bcache/util.h | 2 -
3 files changed, 15 insertions(+), 36 deletions(-)
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -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 {
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -391,12 +391,6 @@ 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)
{
@@ -404,35 +398,25 @@ static void btree_flush_write(struct cac
* 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)) {
- 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);
- }
- }
-
- for (i = c->flush_btree.used / 2 - 1; i >= 0; --i)
- heap_sift(&c->flush_btree, i, journal_min_cmp);
- }
+ best = NULL;
- b = NULL;
- heap_pop(&c->flush_btree, b, journal_min_cmp);
- spin_unlock(&c->journal.lock);
+ 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)->journal,
+ btree_current_write(b)->journal)) {
+ best = b;
+ }
+ }
+ b = best;
if (b) {
mutex_lock(&b->write_lock);
if (!btree_current_write(b)->journal) {
@@ -874,8 +858,7 @@ int bch_journal_alloc(struct cache_set *
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;
--- a/drivers/md/bcache/util.h
+++ b/drivers/md/bcache/util.h
@@ -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; \
