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authorTejun Heo <tj@kernel.org>2014-07-01 10:29:17 -0600
committerJens Axboe <axboe@fb.com>2014-07-01 10:29:17 -0600
commit776687bce42bb22cce48b5da950e48ebbb9a948f (patch)
tree68901461bfd070246574f1e2440ba1ef2ae93ec0
parent531ed6261e7466907418b1a9971a5c71d7d250e4 (diff)
downloadop-kernel-dev-776687bce42bb22cce48b5da950e48ebbb9a948f.zip
op-kernel-dev-776687bce42bb22cce48b5da950e48ebbb9a948f.tar.gz
block, blk-mq: draining can't be skipped even if bypass_depth was non-zero
Currently, both blk_queue_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 <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--block/blk-core.c11
-rw-r--r--block/blk-mq.c7
-rw-r--r--block/blk-sysfs.c2
3 files changed, 10 insertions, 10 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 6f8dba1..0d0bdd6 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 9541f51..f4bdddd 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -131,15 +131,12 @@ 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);
}
static void blk_mq_unfreeze_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)
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