[PATCH 4/5] btrfs: ctree.h: Add btrfs_is_snapshot function

[Marcos Paulo de Souza <marcos.souza.org@gmail.com>]

From: Marcos Paulo de Souza <mpdesouza@suse.com>

This new function takes a btrfs_root as argument, and returns true is
root_key.offset is bigger than 0, meaning that this tree is a snapshot.

This new function will be used by the next patch.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
 fs/btrfs/ctree.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 19d669d12ca1..8502e9082914 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3411,6 +3411,20 @@ static inline int btrfs_defrag_cancelled(struct btrfs_fs_info *fs_info)
 	return signal_pending(current);
 }
 
+/*
+ * btrfs_is_snapshot() - Verify is a tree is a snapshot
+ * @root: btrfs_root
+ *
+ * When the key.offset field of btrfs_root is bigger than 0 it means the referred
+ * tree is a snapshot.
+ *
+ * Returns true if @root refers to a snapshot.
+ */
+static inline bool btrfs_is_snapshot(struct btrfs_root *root)
+{
+	return root->root_key.offset > 0;
+}
+
 #define in_range(b, first, len) ((b) >= (first) && (b) < (first) + (len))
 
 /* Sanity test specific functions */
-- 
2.23.0