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authorTejun Heo <tj@kernel.org>2012-03-05 13:14:59 -0800
committerJens Axboe <axboe@kernel.dk>2012-03-06 21:27:22 +0100
commit6ecf23afab13c39d3bb0e2d826d0984b0dd53733 (patch)
tree48436e2eb507d623ff2c2332aa34e9b7380f33e1
parentd732580b4eb31553c63744a47d590f770cafb8f0 (diff)
block: extend queue bypassing to cover blkcg policies
Extend queue bypassing such that dying queue is always bypassing and blk-throttle is drained on bypass. With blkcg policies updated to test blk_queue_bypass() instead of blk_queue_dead(), this ensures that no bio or request is held by or going through blkcg policies on a bypassing queue. This will be used to implement blkg cleanup on elevator switches and policy changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/blk-core.c12
-rw-r--r--block/blk-throttle.c4
2 files changed, 10 insertions, 6 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 98ddef43009..7713c73d959 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -372,8 +372,7 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
if (q->elevator)
elv_drain_elevator(q);
- if (drain_all)
- blk_throtl_drain(q);
+ blk_throtl_drain(q);
/*
* This function might be called on a queue which failed
@@ -415,8 +414,8 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
*
* In bypass mode, only the dispatch FIFO queue of @q is used. This
* function makes @q enter bypass mode and drains all requests which were
- * issued before. On return, it's guaranteed that no request has ELVPRIV
- * set.
+ * throttled or issued before. On return, it's guaranteed that no request
+ * is being throttled or has ELVPRIV set.
*/
void blk_queue_bypass_start(struct request_queue *q)
{
@@ -461,6 +460,11 @@ void blk_cleanup_queue(struct request_queue *q)
queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
spin_lock_irq(lock);
+
+ /* dead queue is permanently in bypass mode till released */
+ q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+
queue_flag_set(QUEUE_FLAG_NOMERGES, q);
queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
queue_flag_set(QUEUE_FLAG_DEAD, q);
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 5eed6a76721..702c0e64e09 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -310,7 +310,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
struct request_queue *q = td->queue;
/* no throttling for dead queue */
- if (unlikely(blk_queue_dead(q)))
+ if (unlikely(blk_queue_bypass(q)))
return NULL;
rcu_read_lock();
@@ -335,7 +335,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
spin_lock_irq(q->queue_lock);
/* Make sure @q is still alive */
- if (unlikely(blk_queue_dead(q))) {
+ if (unlikely(blk_queue_bypass(q))) {
kfree(tg);
return NULL;
}