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[SRU,C,v2,2/6] blk-wbt: move disable check into get_limit()

Message ID 20190111110843.18042-3-mfo@canonical.com
State New
Headers show
Series blk-wbt: fix for LP#1810998 | expand

Commit Message

Mauricio Faria de Oliveira Jan. 11, 2019, 11:08 a.m. UTC 
From: Jens Axboe <axboe@kernel.dk>

BugLink: https://bugs.launchpad.net/bugs/1810998

Check it in one place, instead of in multiple places.

Tested-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(backported from commit ffa358dcaae1f2f00926484e712e06daa8953cb4)
[mfo: backport:
 - blk-wbt.c:
   - hunk 2: s/rq_wait_inc_below(rqw/atomic_inc_below(&rqw->inflight/
   - hunk 3: s/rq_wait_inc_below(rqw/atomic_inc_below(&rqw->inflight/
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
---
 block/blk-wbt.c | 22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)
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Patch

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 5733d3ab8ed5..84e5cefbb3bb 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -508,6 +508,13 @@  static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw)
 {
 	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;
 
@@ -545,16 +552,6 @@  static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct,
 	struct rq_wait *rqw = get_rq_wait(rwb, wb_acct);
 	DECLARE_WAITQUEUE(wait, current);
 
-	/*
-	* 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)
 		&& atomic_inc_below(&rqw->inflight, get_limit(rwb, rw)))
 		return;
@@ -563,11 +560,6 @@  static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct,
 	do {
 		set_current_state(TASK_UNINTERRUPTIBLE);
 
-		if (!rwb_enabled(rwb)) {
-			atomic_inc(&rqw->inflight);
-			break;
-		}
-
 		if (atomic_inc_below(&rqw->inflight, get_limit(rwb, rw)))
 			break;