[PATCH v2 15/18] fs/ceph/super: move `ceph_cap.caps_item` into the union

The `caps_item` field is only used if the `ceph_cap` object is
"reserved", i.e. when it is in the `ceph_mds_client.caps_list` list
(but is otherwise uninitialized).

This reduces the size of the struct by 16 bytes.

Signed-off-by: Max Kellermann <[email protected]>
---
 fs/ceph/super.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index abe403eff0bb..afe681a47f71 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -208,6 +208,14 @@ struct ceph_cap {
 	struct list_head session_caps;   /* per-session caplist */
 	u64 cap_id;       /* unique cap id (mds provided) */
 	union {
+		/* reserved caps */
+		struct {
+			/**
+			 * For the `ceph_mds_client.caps_list` list.
+			 * Protected by `caps_list_lock`.
+			 */
+			struct list_head caps_item;
+		};
 		/* in-use caps */
 		struct {
 			int issued;       /* latest, from the mds */
@@ -224,7 +232,6 @@ struct ceph_cap {
 	};
 	u32 seq, issue_seq, mseq;
 	u32 cap_gen;      /* active/stale cycle */
-	struct list_head caps_item;
 };
 
 #define CHECK_CAPS_AUTHONLY     1  /* only check auth cap */
-- 
2.47.3