[2/3] btrfs: reduce additional fs_info->reada_lock in reada_find_zone
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Message ID c0fb11e32a35edcce2b88a082b15b381909ad7c8.1450447809.git.zhaolei@cn.fujitsu.com
State New
Headers show

Commit Message

Zhaolei Dec. 18, 2015, 2:10 p.m. UTC
We can avoid additional locking-acquirment and one pair of
kref_get/put by combine two condition.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 fs/btrfs/reada.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

Patch
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diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 6fb9c37..d8116fe 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -260,18 +260,14 @@  static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 	spin_lock(&fs_info->reada_lock);
 	ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
 				     logical >> PAGE_CACHE_SHIFT, 1);
-	if (ret == 1)
+	if (ret == 1 && logical >= zone->start && logical <= zone->end) {
 		kref_get(&zone->refcnt);
-	spin_unlock(&fs_info->reada_lock);
-
-	if (ret == 1) {
-		if (logical >= zone->start && logical <= zone->end)
-			return zone;
-		spin_lock(&fs_info->reada_lock);
-		kref_put(&zone->refcnt, reada_zone_release);
 		spin_unlock(&fs_info->reada_lock);
+		return zone;
 	}
 
+	spin_unlock(&fs_info->reada_lock);
+
 	cache = btrfs_lookup_block_group(fs_info, logical);
 	if (!cache)
 		return NULL;