fs: btrfs: Fix usage of uninitialized variables

The variable res should be initialized to 0 in these functions,
because if the searched key is not found, the variable is used
uninitialized.

Reported-by: Coverity (CID: 167335)
Reported-by: Coverity (CID: 167336)
Reported-by: Coverity (CID: 167337)
Signed-off-by: Marek Behun <marek.behun@nic.cz>
diff --git a/fs/btrfs/chunk-map.c b/fs/btrfs/chunk-map.c
index 48407f3..ce7330b 100644
--- a/fs/btrfs/chunk-map.c
+++ b/fs/btrfs/chunk-map.c
@@ -147,7 +147,7 @@
 	struct btrfs_path path;
 	struct btrfs_key key, *found_key;
 	struct btrfs_chunk *chunk;
-	int res;
+	int res = 0;
 
 	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
 	key.type = BTRFS_CHUNK_ITEM_KEY;
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index decf86e..9705634 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -93,7 +93,7 @@
 	struct btrfs_path path;
 	struct btrfs_key key, *found_key;
 	struct btrfs_dir_item *item;
-	int res;
+	int res = 0;
 
 	key.objectid = dir;
 	key.type = BTRFS_DIR_INDEX_KEY;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0d3da28..0af0427 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -324,7 +324,7 @@
 	struct btrfs_path path;
 	struct btrfs_key key;
 	struct btrfs_file_extent_item *extent;
-	int res;
+	int res = 0;
 	u64 rd, rd_all = -1ULL;
 
 	key.objectid = inr;