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

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This reverts commit c4dc2497d5.

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: c4dc2497d5 ("bcache: fix high CPU occupancy during journal")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Cc: Tang Junhui <tang.junhui.linux@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Coly Li 2019-06-28 19:59:54 +08:00 committed by Jens Axboe
parent ba82c1ac16
commit 249a5f6da5
3 changed files with 15 additions and 36 deletions
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2
drivers/md/bcache/bcache.h
View File

@ -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 {

47
drivers/md/bcache/journal.c
View File

@ -416,12 +416,6 @@ int bch_journal_replay(struct cache_set *s, struct list_head *list)
}
/* 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)) {
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);
}
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)->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;

2
drivers/md/bcache/util.h
View File

@ -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; \