Btrfs: remove nr_async_submits and async_submit_draining

Now that we have the combo of flushing twice, which can make sure IO
have started since the second flush will wait for page lock which
won't be unlocked unless setting page writeback and queuing ordered
extents, we don't need %async_submit_draining, %async_delalloc_pages
and %nr_async_submits to tell whether the IO has actually started.

Moreover, all the flushers in use are followed by functions that wait
for ordered extents to complete, so %nr_async_submits, which tracks
whether bio's async submit has made progress, doesn't really make
sense.

However, %async_delalloc_pages is still required by shrink_delalloc()
as that function doesn't flush twice in the normal case (just issues a
writeback with WB_REASON_FS_FREE_SPACE).

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 0 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index bc1b6a033700..7995666af959 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -878,8 +878,6 @@ struct btrfs_fs_info {
 	rwlock_t tree_mod_log_lock;
 	struct rb_root tree_mod_log;
 
-	atomic_t nr_async_submits;
-	atomic_t async_submit_draining;
 	atomic_t async_delalloc_pages;
 	atomic_t open_ioctl_trans;