[PATCH] btrfs: don't needlessly create extent-refs kernel thread

[PATCH] btrfs: don't needlessly create extent-refs kernel thread

[David Sterba]

The patch 32b593bfcb58 ("Btrfs: remove no longer used function to run
delayed refs asynchronously") removed the async delayed refs but the
thread has been created, without any use. Remove it to avoid resource
consumption.

Fixes: 32b593bfcb58 ("Btrfs: remove no longer used function to run delayed refs asynchronously")
CC: stable@vger.kernel.org # 5.2+
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/ctree.h   | 2 --
 fs/btrfs/disk-io.c | 6 ------
 2 files changed, 8 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d17e79a40930..ba7981478558 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -734,8 +734,6 @@ struct btrfs_fs_info {
 	struct btrfs_workqueue *fixup_workers;
 	struct btrfs_workqueue *delayed_workers;
 
-	/* the extent workers do delayed refs on the extent allocation tree */
-	struct btrfs_workqueue *extent_workers;
 	struct task_struct *transaction_kthread;
 	struct task_struct *cleaner_kthread;
 	u32 thread_pool_size;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7d6886f70f8f..5d32deb42993 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2002,7 +2002,6 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
 	btrfs_destroy_workqueue(fs_info->readahead_workers);
 	btrfs_destroy_workqueue(fs_info->flush_workers);
 	btrfs_destroy_workqueue(fs_info->qgroup_rescan_workers);
-	btrfs_destroy_workqueue(fs_info->extent_workers);
 	/*
 	 * Now that all other work queues are destroyed, we can safely destroy
 	 * the queues used for metadata I/O, since tasks from those other work
@@ -2198,10 +2197,6 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info,
 				      max_active, 2);
 	fs_info->qgroup_rescan_workers =
 		btrfs_alloc_workqueue(fs_info, "qgroup-rescan", flags, 1, 0);
-	fs_info->extent_workers =
-		btrfs_alloc_workqueue(fs_info, "extent-refs", flags,
-				      min_t(u64, fs_devices->num_devices,
-					    max_active), 8);
 
 	if (!(fs_info->workers && fs_info->delalloc_workers &&
 	      fs_info->flush_workers &&
@@ -2212,7 +2207,6 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info,
 	      fs_info->endio_freespace_worker && fs_info->rmw_workers &&
 	      fs_info->caching_workers && fs_info->readahead_workers &&
 	      fs_info->fixup_workers && fs_info->delayed_workers &&
-	      fs_info->extent_workers &&
 	      fs_info->qgroup_rescan_workers)) {
 		return -ENOMEM;
 	}
-- 
2.23.0

Re: [PATCH] btrfs: don't needlessly create extent-refs kernel thread

[Josef Bacik]

On Sat, Oct 12, 2019 at 06:42:10PM +0200, David Sterba wrote:
> The patch 32b593bfcb58 ("Btrfs: remove no longer used function to run
> delayed refs asynchronously") removed the async delayed refs but the
> thread has been created, without any use. Remove it to avoid resource
> consumption.
> 
> Fixes: 32b593bfcb58 ("Btrfs: remove no longer used function to run delayed refs asynchronously")
> CC: stable@vger.kernel.org # 5.2+
> Signed-off-by: David Sterba <dsterba@suse.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef