Currently, both blk_queeu_bypass_start() and blk_mq_freeze_queue()
skip queue draining if bypass_depth was already above zero. The
assumption is that the one which bumped the bypass_depth should have
performed draining already; however, there's nothing which prevents a
new instance of bypassing/freezing from starting before the previous
one finishes draining. The current code may allow the later
bypassing/freezing instances to complete while there still are
in-flight requests which haven't finished draining.
Fix it by draining regardless of bypass_depth. We still skip draining
from blk_queue_bypass_start() while the queue is initializing to avoid
introducing excessive delays during boot. INIT_DONE setting is moved
above the initial blk_queue_bypass_end() so that bypassing attempts
can't slip inbetween.
Signed-off-by: Tejun Heo <t...@kernel.org>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: Nicholas A. Bellinger <n...@linux-iscsi.org>
---
block/blk-core.c | 11 +++++++----
block/blk-mq.c | 7 ++-----
block/blk-sysfs.c | 2 +-
3 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index f6f6b9a..2375130 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -438,14 +438,17 @@ static void __blk_drain_queue(struct request_queue *q,
bool drain_all)
*/
void blk_queue_bypass_start(struct request_queue *q)
{
- bool drain;
-
spin_lock_irq(q->queue_lock);
- drain = !q->bypass_depth++;
+ q->bypass_depth++;
queue_flag_set(QUEUE_FLAG_BYPASS, q);
spin_unlock_irq(q->queue_lock);
- if (drain) {
+ /*
+ * Queues start drained. Skip actual draining till init is
+ * complete. This avoids lenghty delays during queue init which
+ * can happen many times during boot.
+ */
+ if (blk_queue_init_done(q)) {
spin_lock_irq(q->queue_lock);
__blk_drain_queue(q, false);
spin_unlock_irq(q->queue_lock);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1c09d57..c0122a4 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -131,15 +131,12 @@ static void __blk_mq_drain_queue(struct request_queue *q)
*/
static void blk_mq_freeze_queue(struct request_queue *q)
{
- bool drain;
-
spin_lock_irq(q->queue_lock);
- drain = !q->bypass_depth++;
+ q->bypass_depth++;
queue_flag_set(QUEUE_FLAG_BYPASS, q);
spin_unlock_irq(q->queue_lock);
- if (drain)
- __blk_mq_drain_queue(q);
+ __blk_mq_drain_queue(q);
}
void blk_mq_drain_queue(struct request_queue *q)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 23321fb..4db5abf 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -554,8 +554,8 @@ int blk_register_queue(struct gendisk *disk)
* Initialization must be complete by now. Finish the initial
* bypass from queue allocation.
*/
- blk_queue_bypass_end(q);
queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
+ blk_queue_bypass_end(q);
ret = blk_trace_init_sysfs(dev);
if (ret)
--
1.9.3
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