[02/10] btrfs: reada: Move is_need_to_readahead contition earlier

Commit Message

Zhaolei Dec. 31, 2015, 3:03 p.m. UTC

Move is_need_to_readahead contition earlier to avoid useless loop
to get relative data for readahead.

Signed-off-by: Zhao Lei <[e-mail]>
---
 fs/btrfs/reada.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

Patch

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index fb21bf0..dcc5b69 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -665,7 +665,6 @@  static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 	u64 logical;
 	int ret;
 	int i;
-	int need_kick = 0;
 
 	spin_lock(&fs_info->reada_lock);
 	if (dev->reada_curr_zone == NULL) {
@@ -701,6 +700,15 @@  static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 
 	spin_unlock(&fs_info->reada_lock);
 
+	spin_lock(&re->lock);
+		if (re->scheduled_for || list_empty(&re->extctl)) {
+			spin_unlock(&re->lock);
+			reada_extent_put(fs_info, re);
+			return 0;
+		}
+		re->scheduled_for = dev;
+	spin_unlock(&re->lock);
+
 	/*
 	 * find mirror num
 	 */
@@ -712,18 +720,8 @@  static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 	}
 	logical = re->logical;
 
-	spin_lock(&re->lock);
-	if (!re->scheduled_for && !list_empty(&re->extctl)) {
-		re->scheduled_for = dev;
-		need_kick = 1;
-	}
-	spin_unlock(&re->lock);
-
 	reada_extent_put(fs_info, re);
 
-	if (!need_kick)
-		return 0;
-
 	atomic_inc(&dev->reada_in_flight);
 	ret = reada_tree_block_flagged(fs_info->extent_root, logical,
 			mirror_num, &eb);