This function is used to cancel all throttled bios when queue is
dying. Noted this modification is mainly from revertion of commit
b77412372b68 ("blk-throttle: remove blk_throtl_drain").
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/blk-throttle.c | 39 +++++++++++++++++++++++++++++++++++++++
block/blk.h | 2 ++
2 files changed, 41 insertions(+)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 3892ead7a0b5..4227dcf2dd3b 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2435,6 +2435,45 @@ static void tg_drain_bios(struct throtl_service_queue *parent_sq)
}
}
+/**
+ * blk_throtl_cancel_bios - cancel throttled bios
+ * @q: request_queue to cancel throttled bios for
+ *
+ * This function is called when queue is dying, error all currently
+ * throttled bios on @q so that user threads that are waiting for the bios
+ * can exit.
+ */
+void blk_throtl_cancel_bios(struct request_queue *q)
+{
+ struct throtl_data *td = q->td;
+ struct blkcg_gq *blkg;
+ struct cgroup_subsys_state *pos_css;
+ struct bio *bio;
+ int rw;
+
+ rcu_read_lock();
+
+ /*
+ * Drain each tg while doing post-order walk on the blkg tree, so
+ * that all bios are propagated to td->service_queue. It'd be
+ * better to walk service_queue tree directly but blkg walk is
+ * easier.
+ */
+ blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg)
+ tg_drain_bios(&blkg_to_tg(blkg)->service_queue);
+
+ /* finally, transfer bios from top-level tg's into the td */
+ tg_drain_bios(&td->service_queue);
+
+ rcu_read_unlock();
+
+ /* all bios now should be in td->service_queue, cancel them */
+ for (rw = READ; rw <= WRITE; rw++)
+ while ((bio = throtl_pop_queued(&td->service_queue.queued[rw],
+ NULL)))
+ bio_io_error(bio);
+}
+
int blk_throtl_init(struct request_queue *q)
{
struct throtl_data *td;
diff --git a/block/blk.h b/block/blk.h
index 7d2a0ba7ed21..c407581a3a19 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -287,12 +287,14 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
* Internal throttling interface
*/
#ifdef CONFIG_BLK_DEV_THROTTLING
+extern void blk_throtl_cancel_bios(struct request_queue *q);
extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
extern void blk_throtl_register_queue(struct request_queue *q);
extern void blk_throtl_charge_bio_split(struct bio *bio);
bool blk_throtl_bio(struct bio *bio);
#else /* CONFIG_BLK_DEV_THROTTLING */
+static inline void blk_throtl_cancel_bios(struct request_queue *q) { }
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
static inline void blk_throtl_register_queue(struct request_queue *q) { }
--
2.31.1
