linux-kernel - [PATCH 1/2] btrfs: cleaner_kthread() doesn't need explicit freeze

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Date:	Tue, 15 Mar 2016 11:28:54 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
	David Sterba <dsterba@...e.com>
cc:	linux-btrfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
	jack@...e.cz, mhocko@...e.cz
Subject: [PATCH 1/2] btrfs: cleaner_kthread() doesn't need explicit freeze

cleaner_kthread() is not marked freezable, and therefore calling 
try_to_freeze() in its context is a pointless no-op.

In addition to that, as has been clearly demonstrated by 80ad623edd2d 
("Revert "btrfs: clear PF_NOFREEZE in cleaner_kthread()"), it's perfectly 
valid / legal for cleaner_kthread() to stay scheduled out in an arbitrary 
place during suspend (in that particular example that was waiting for 
reading of extent pages), so there is no need to leave any traces of 
freezer in this kthread.

Fixes: 80ad623edd2d ("Revert "btrfs: clear PF_NOFREEZE in cleaner_kthread()")
Fixes: 696249132158 ("btrfs: clear PF_NOFREEZE in cleaner_kthread()")
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---
 fs/btrfs/disk-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4545e2e..d8d68af 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1830,7 +1830,7 @@ static int cleaner_kthread(void *arg)
 		 */
 		btrfs_delete_unused_bgs(root->fs_info);
 sleep:
-		if (!try_to_freeze() && !again) {
+		if (!again) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			if (!kthread_should_stop())
 				schedule();
-- 
Jiri Kosina
SUSE Labs