[PATCH 5.13 078/151] io-wq: fix bug of creating io-wokers unconditionally

Greg Kroah-Hartman
2021-08-16T13:25:54Z

From: Hao Xu <haoxu@linux.alibaba.com>

[ Upstream commit 49e7f0c789add1330b111af0b7caeb0e87df063e ]

The former patch to add check between nr_workers and max_workers has a
bug, which will cause unconditionally creating io-workers. That's
because the result of the check doesn't affect the call of
create_io_worker(), fix it by bringing in a boolean value for it.

Fixes: 21698274da5b ("io-wq: fix lack of acct->nr_workers < acct->max_workers judgement")
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20210808135434.68667-2-haoxu@linux.alibaba.com
[axboe: drop hunk that isn't strictly needed]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/io-wq.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 77026d42cb79..2c8a9a394884 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -283,16 +283,24 @@ static void create_worker_cb(struct callback_head *cb)
struct io_wq *wq;
struct io_wqe *wqe;
struct io_wqe_acct *acct;
+ bool do_create = false;

cwd = container_of(cb, struct create_worker_data, work);
wqe = cwd->wqe;
wq = wqe->wq;
acct = &wqe->acct[cwd->index];
raw_spin_lock_irq(&wqe->lock);
- if (acct->nr_workers < acct->max_workers)
+ if (acct->nr_workers < acct->max_workers) {
acct->nr_workers++;
+ do_create = true;
+ }
raw_spin_unlock_irq(&wqe->lock);
- create_io_worker(wq, cwd->wqe, cwd->index);
+ if (do_create) {
+ create_io_worker(wq, cwd->wqe, cwd->index);
+ } else {
+ atomic_dec(&acct->nr_running);
+ io_worker_ref_put(wq);
+ }
kfree(cwd);
}

--
2.30.2