Merge tag 'for-linus-20180825' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
"A few small fixes for this merge window:
- Locking imbalance fix for bcache (Shan Hai)
- A few small fixes for wbt. One is a cleanup/prep, one is a fix for
an existing issue, and the last two are fixes for changes that went
into this merge window (me)"
* tag 'for-linus-20180825' of git://git.kernel.dk/linux-block:
blk-wbt: don't maintain inflight counts if disabled
blk-wbt: fix has-sleeper queueing check
blk-wbt: use wq_has_sleeper() for wq active check
blk-wbt: move disable check into get_limit()
bcache: release dc->writeback_lock properly in bch_writeback_thread()
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index bb109bb..3772671 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -453,9 +453,26 @@
else if (val >= 0)
val *= 1000ULL;
- wbt_set_min_lat(q, val);
+ /*
+ * Ensure that the queue is idled, in case the latency update
+ * ends up either enabling or disabling wbt completely. We can't
+ * have IO inflight if that happens.
+ */
+ if (q->mq_ops) {
+ blk_mq_freeze_queue(q);
+ blk_mq_quiesce_queue(q);
+ } else
+ blk_queue_bypass_start(q);
+ wbt_set_min_lat(q, val);
wbt_update_limits(q);
+
+ if (q->mq_ops) {
+ blk_mq_unquiesce_queue(q);
+ blk_mq_unfreeze_queue(q);
+ } else
+ blk_queue_bypass_end(q);
+
return count;
}
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index bb93c7c..84507d3 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -118,7 +118,7 @@
for (i = 0; i < WBT_NUM_RWQ; i++) {
struct rq_wait *rqw = &rwb->rq_wait[i];
- if (waitqueue_active(&rqw->wait))
+ if (wq_has_sleeper(&rqw->wait))
wake_up_all(&rqw->wait);
}
}
@@ -162,7 +162,7 @@
if (inflight && inflight >= limit)
return;
- if (waitqueue_active(&rqw->wait)) {
+ if (wq_has_sleeper(&rqw->wait)) {
int diff = limit - inflight;
if (!inflight || diff >= rwb->wb_background / 2)
@@ -449,6 +449,13 @@
{
unsigned int limit;
+ /*
+ * If we got disabled, just return UINT_MAX. This ensures that
+ * we'll properly inc a new IO, and dec+wakeup at the end.
+ */
+ if (!rwb_enabled(rwb))
+ return UINT_MAX;
+
if ((rw & REQ_OP_MASK) == REQ_OP_DISCARD)
return rwb->wb_background;
@@ -485,31 +492,17 @@
{
struct rq_wait *rqw = get_rq_wait(rwb, wb_acct);
DECLARE_WAITQUEUE(wait, current);
+ bool has_sleeper;
- /*
- * inc it here even if disabled, since we'll dec it at completion.
- * this only happens if the task was sleeping in __wbt_wait(),
- * and someone turned it off at the same time.
- */
- if (!rwb_enabled(rwb)) {
- atomic_inc(&rqw->inflight);
- return;
- }
-
- if (!waitqueue_active(&rqw->wait)
- && rq_wait_inc_below(rqw, get_limit(rwb, rw)))
+ has_sleeper = wq_has_sleeper(&rqw->wait);
+ if (!has_sleeper && rq_wait_inc_below(rqw, get_limit(rwb, rw)))
return;
add_wait_queue_exclusive(&rqw->wait, &wait);
do {
set_current_state(TASK_UNINTERRUPTIBLE);
- if (!rwb_enabled(rwb)) {
- atomic_inc(&rqw->inflight);
- break;
- }
-
- if (rq_wait_inc_below(rqw, get_limit(rwb, rw)))
+ if (!has_sleeper && rq_wait_inc_below(rqw, get_limit(rwb, rw)))
break;
if (lock) {
@@ -518,6 +511,7 @@
spin_lock_irq(lock);
} else
io_schedule();
+ has_sleeper = false;
} while (1);
__set_current_state(TASK_RUNNING);
@@ -546,6 +540,9 @@
{
enum wbt_flags flags = 0;
+ if (!rwb_enabled(rwb))
+ return 0;
+
if (bio_op(bio) == REQ_OP_READ) {
flags = WBT_READ;
} else if (wbt_should_throttle(rwb, bio)) {
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 6be05bd..08c3a9f 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -685,8 +685,10 @@
* data on cache. BCACHE_DEV_DETACHING flag is set in
* bch_cached_dev_detach().
*/
- if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
+ if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) {
+ up_write(&dc->writeback_lock);
break;
+ }
}
up_write(&dc->writeback_lock);
