Merge tag 'io_uring-5.16-2021-11-13' of git://git.kernel.dk/linux-block
Pull io_uring fix from Jens Axboe:
"Just a single fix here for a buffered write hash stall, which is also
affecting stable"
* tag 'io_uring-5.16-2021-11-13' of git://git.kernel.dk/linux-block:
io-wq: serialize hash clear with wakeup
diff --git a/fs/io-wq.c b/fs/io-wq.c
index afd955d..88202de 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -423,9 +423,10 @@ static inline unsigned int io_get_work_hash(struct io_wq_work *work)
return work->flags >> IO_WQ_HASH_SHIFT;
}
-static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
+static bool io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
{
struct io_wq *wq = wqe->wq;
+ bool ret = false;
spin_lock_irq(&wq->hash->wait.lock);
if (list_empty(&wqe->wait.entry)) {
@@ -433,9 +434,11 @@ static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
if (!test_bit(hash, &wq->hash->map)) {
__set_current_state(TASK_RUNNING);
list_del_init(&wqe->wait.entry);
+ ret = true;
}
}
spin_unlock_irq(&wq->hash->wait.lock);
+ return ret;
}
static struct io_wq_work *io_get_next_work(struct io_wqe_acct *acct,
@@ -475,14 +478,21 @@ static struct io_wq_work *io_get_next_work(struct io_wqe_acct *acct,
}
if (stall_hash != -1U) {
+ bool unstalled;
+
/*
* Set this before dropping the lock to avoid racing with new
* work being added and clearing the stalled bit.
*/
set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
raw_spin_unlock(&wqe->lock);
- io_wait_on_hash(wqe, stall_hash);
+ unstalled = io_wait_on_hash(wqe, stall_hash);
raw_spin_lock(&wqe->lock);
+ if (unstalled) {
+ clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+ if (wq_has_sleeper(&wqe->wq->hash->wait))
+ wake_up(&wqe->wq->hash->wait);
+ }
}
return NULL;
@@ -564,8 +574,11 @@ static void io_worker_handle_work(struct io_worker *worker)
io_wqe_enqueue(wqe, linked);
if (hash != -1U && !next_hashed) {
+ /* serialize hash clear with wake_up() */
+ spin_lock_irq(&wq->hash->wait.lock);
clear_bit(hash, &wq->hash->map);
clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+ spin_unlock_irq(&wq->hash->wait.lock);
if (wq_has_sleeper(&wq->hash->wait))
wake_up(&wq->hash->wait);
raw_spin_lock(&wqe->lock);