linux-kernel - [PATCH 27/48] writeback, blkcg: propagate non-root blkcg congestion state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1427086499-15657-28-git-send-email-tj@kernel.org>
Date:	Mon, 23 Mar 2015 00:54:38 -0400
From:	Tejun Heo <tj@...nel.org>
To:	axboe@...nel.dk
Cc:	linux-kernel@...r.kernel.org, jack@...e.cz, hch@...radead.org,
	hannes@...xchg.org, linux-fsdevel@...r.kernel.org,
	vgoyal@...hat.com, lizefan@...wei.com, cgroups@...r.kernel.org,
	linux-mm@...ck.org, mhocko@...e.cz, clm@...com,
	fengguang.wu@...el.com, david@...morbit.com, gthelen@...gle.com,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 27/48] writeback, blkcg: propagate non-root blkcg congestion state

Now that bdi layer can handle per-blkcg bdi_writeback_congested state,
blk_{set|clear}_congested() can propagate non-root blkcg congestion
state to them.

This can be easily achieved by disabling the root_rl tests in
blk_{set|clear}_congested().  Note that we still need those tests when
!CONFIG_CGROUP_WRITEBACK as otherwise we'll end up flipping root blkcg
wb's congestion state for events happening on other blkcgs.

v2: Updated for bdi_writeback_congested.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Jan Kara <jack@...e.cz>
Cc: Vivek Goyal <vgoyal@...hat.com>
---
 block/blk-core.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index cad26e3..95488fb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -65,23 +65,26 @@ static struct workqueue_struct *kblockd_workqueue;
 
 static void blk_clear_congested(struct request_list *rl, int sync)
 {
-	if (rl != &rl->q->root_rl)
-		return;
 #ifdef CONFIG_CGROUP_WRITEBACK
 	clear_wb_congested(rl->blkg->wb_congested, sync);
 #else
-	clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
+	/*
+	 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
+	 * flip its congestion state for events on other blkcgs.
+	 */
+	if (rl == &rl->q->root_rl)
+		clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
 #endif
 }
 
 static void blk_set_congested(struct request_list *rl, int sync)
 {
-	if (rl != &rl->q->root_rl)
-		return;
 #ifdef CONFIG_CGROUP_WRITEBACK
 	set_wb_congested(rl->blkg->wb_congested, sync);
 #else
-	set_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
+	/* see blk_clear_congested() */
+	if (rl == &rl->q->root_rl)
+		set_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
 #endif
 }
 
-- 
2.1.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/