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-rw-r--r--block/bfq-iosched.c32
1 files changed, 26 insertions, 6 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 0319d6339822..0c6214497fcc 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2713,6 +2713,28 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
}
}
+
+static
+void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /*
+ * To prevent bfqq's service guarantees from being violated,
+ * bfqq may be left busy, i.e., queued for service, even if
+ * empty (see comments in __bfq_bfqq_expire() for
+ * details). But, if no process will send requests to bfqq any
+ * longer, then there is no point in keeping bfqq queued for
+ * service. In addition, keeping bfqq queued for service, but
+ * with no process ref any longer, may have caused bfqq to be
+ * freed when dequeued from service. But this is assumed to
+ * never happen.
+ */
+ if (bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list) &&
+ bfqq != bfqd->in_service_queue)
+ bfq_del_bfqq_busy(bfqd, bfqq, false);
+
+ bfq_put_queue(bfqq);
+}
+
static void
bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
@@ -2783,8 +2805,7 @@ bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
*/
new_bfqq->pid = -1;
bfqq->bic = NULL;
- /* release process reference to bfqq */
- bfq_put_queue(bfqq);
+ bfq_release_process_ref(bfqd, bfqq);
}
static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
@@ -4899,7 +4920,7 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
bfq_put_cooperator(bfqq);
- bfq_put_queue(bfqq); /* release process reference */
+ bfq_release_process_ref(bfqd, bfqq);
}
static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
@@ -5001,8 +5022,7 @@ static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
bfqq = bic_to_bfqq(bic, false);
if (bfqq) {
- /* release process reference on this queue */
- bfq_put_queue(bfqq);
+ bfq_release_process_ref(bfqd, bfqq);
bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
bic_set_bfqq(bic, bfqq, false);
}
@@ -5963,7 +5983,7 @@ bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
bfq_put_cooperator(bfqq);
- bfq_put_queue(bfqq);
+ bfq_release_process_ref(bfqq->bfqd, bfqq);
return NULL;
}