nilfs2: remove bmap pointer operations

Previously, the bmap codes of nilfs used three types of function
tables.  The abuse of indirect function calls decreased source
readability and suffered many indirect jumps which would confuse
branch prediction of processors.

This eliminates one type of the function tables,
nilfs_bmap_ptr_operations, which was used to dispatch low level
pointer operations of the nilfs bmap.

This adds a new integer variable "b_ptr_type" to nilfs_bmap struct,
and uses the value to select the pointer operations.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 78 insertions, 32 deletions

diff --git a/fs/nilfs2/bmap.h b/fs/nilfs2/bmap.h
index 28c77bb71bb7..47f5b74713c0 100644
--- a/fs/nilfs2/bmap.h
+++ b/fs/nilfs2/bmap.h
@@ -86,27 +86,6 @@ struct nilfs_bmap_operations {
 };
 
 
-/**
- * struct nilfs_bmap_ptr_operations - bmap ptr operation table
- */
-struct nilfs_bmap_ptr_operations {
-        int (*bpop_prepare_alloc_ptr)(struct nilfs_bmap *,
-                                      union nilfs_bmap_ptr_req *);
-        void (*bpop_commit_alloc_ptr)(struct nilfs_bmap *,
-                                      union nilfs_bmap_ptr_req *);
-        void (*bpop_abort_alloc_ptr)(struct nilfs_bmap *,
-                                     union nilfs_bmap_ptr_req *);
-        int (*bpop_prepare_end_ptr)(struct nilfs_bmap *,
-                                    union nilfs_bmap_ptr_req *);
-        void (*bpop_commit_end_ptr)(struct nilfs_bmap *,
-                                    union nilfs_bmap_ptr_req *);
-        void (*bpop_abort_end_ptr)(struct nilfs_bmap *,
-                                   union nilfs_bmap_ptr_req *);
-
-        int (*bpop_translate)(const struct nilfs_bmap *, __u64, __u64 *);
-};
-
-
 #define NILFS_BMAP_SIZE         (NILFS_INODE_BMAP_SIZE * sizeof(__le64))
 #define NILFS_BMAP_KEY_BIT      (sizeof(unsigned long) * 8 /* CHAR_BIT */)
 #define NILFS_BMAP_NEW_PTR_INIT \
@@ -124,9 +103,9 @@ static inline int nilfs_bmap_is_new_ptr(unsigned long ptr)
  * @b_sem: semaphore
  * @b_inode: owner of bmap
  * @b_ops: bmap operation table
- * @b_pops: bmap ptr operation table
  * @b_last_allocated_key: last allocated key for data block
  * @b_last_allocated_ptr: last allocated ptr for data block
+ * @b_ptr_type: pointer type
  * @b_state: state
  */
 struct nilfs_bmap {
@@ -137,12 +116,22 @@ struct nilfs_bmap {
         struct rw_semaphore b_sem;
         struct inode *b_inode;
         const struct nilfs_bmap_operations *b_ops;
-        const struct nilfs_bmap_ptr_operations *b_pops;
         __u64 b_last_allocated_key;
         __u64 b_last_allocated_ptr;
+        int b_ptr_type;
         int b_state;
 };
 
+/* pointer type */
+#define NILFS_BMAP_PTR_P        0       /* physical block number (i.e. LBN) */
+#define NILFS_BMAP_PTR_VS       1       /* virtual block number (single
+                                           version) */
+#define NILFS_BMAP_PTR_VM       2       /* virtual block number (has multiple
+                                           versions) */
+#define NILFS_BMAP_PTR_U        (-1)    /* never perform pointer operations */
+
+#define NILFS_BMAP_USE_VBN(bmap)        ((bmap)->b_ptr_type > 0)
+
 /* state */
 #define NILFS_BMAP_DIRTY        0x00000001
 
@@ -171,6 +160,63 @@ void nilfs_bmap_commit_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
 /*
  * Internal use only
  */
+int nilfs_bmap_prepare_alloc_v(struct nilfs_bmap *,
+                               union nilfs_bmap_ptr_req *);
+void nilfs_bmap_commit_alloc_v(struct nilfs_bmap *,
+                               union nilfs_bmap_ptr_req *);
+void nilfs_bmap_abort_alloc_v(struct nilfs_bmap *,
+                              union nilfs_bmap_ptr_req *);
+
+static inline int nilfs_bmap_prepare_alloc_ptr(struct nilfs_bmap *bmap,
+                                               union nilfs_bmap_ptr_req *req)
+{
+        if (NILFS_BMAP_USE_VBN(bmap))
+                return nilfs_bmap_prepare_alloc_v(bmap, req);
+        /* ignore target ptr */
+        req->bpr_ptr = bmap->b_last_allocated_ptr++;
+        return 0;
+}
+
+static inline void nilfs_bmap_commit_alloc_ptr(struct nilfs_bmap *bmap,
+                                               union nilfs_bmap_ptr_req *req)
+{
+        if (NILFS_BMAP_USE_VBN(bmap))
+                nilfs_bmap_commit_alloc_v(bmap, req);
+}
+
+static inline void nilfs_bmap_abort_alloc_ptr(struct nilfs_bmap *bmap,
+                                              union nilfs_bmap_ptr_req *req)
+{
+        if (NILFS_BMAP_USE_VBN(bmap))
+                nilfs_bmap_abort_alloc_v(bmap, req);
+        else
+                bmap->b_last_allocated_ptr--;
+}
+
+int nilfs_bmap_prepare_end_v(struct nilfs_bmap *, union nilfs_bmap_ptr_req *);
+void nilfs_bmap_commit_end_v(struct nilfs_bmap *, union nilfs_bmap_ptr_req *);
+void nilfs_bmap_abort_end_v(struct nilfs_bmap *, union nilfs_bmap_ptr_req *);
+
+static inline int nilfs_bmap_prepare_end_ptr(struct nilfs_bmap *bmap,
+                                             union nilfs_bmap_ptr_req *req)
+{
+        return NILFS_BMAP_USE_VBN(bmap) ?
+                nilfs_bmap_prepare_end_v(bmap, req) : 0;
+}
+
+static inline void nilfs_bmap_commit_end_ptr(struct nilfs_bmap *bmap,
+                                             union nilfs_bmap_ptr_req *req)
+{
+        if (NILFS_BMAP_USE_VBN(bmap))
+                nilfs_bmap_commit_end_v(bmap, req);
+}
+
+static inline void nilfs_bmap_abort_end_ptr(struct nilfs_bmap *bmap,
+                                            union nilfs_bmap_ptr_req *req)
+{
+        if (NILFS_BMAP_USE_VBN(bmap))
+                nilfs_bmap_abort_end_v(bmap, req);
+}
 
 int nilfs_bmap_start_v(struct nilfs_bmap *, union nilfs_bmap_ptr_req *,
                        sector_t);
@@ -184,15 +230,15 @@ __u64 nilfs_bmap_data_get_key(const struct nilfs_bmap *,
 __u64 nilfs_bmap_find_target_seq(const struct nilfs_bmap *, __u64);
 __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *);
 
-int nilfs_bmap_prepare_update(struct nilfs_bmap *,
-                              union nilfs_bmap_ptr_req *,
-                              union nilfs_bmap_ptr_req *);
-void nilfs_bmap_commit_update(struct nilfs_bmap *,
-                              union nilfs_bmap_ptr_req *,
-                              union nilfs_bmap_ptr_req *);
-void nilfs_bmap_abort_update(struct nilfs_bmap *,
-                             union nilfs_bmap_ptr_req *,
-                             union nilfs_bmap_ptr_req *);
+int nilfs_bmap_prepare_update_v(struct nilfs_bmap *,
+                                union nilfs_bmap_ptr_req *,
+                                union nilfs_bmap_ptr_req *);
+void nilfs_bmap_commit_update_v(struct nilfs_bmap *,
+                                union nilfs_bmap_ptr_req *,
+                                union nilfs_bmap_ptr_req *);
+void nilfs_bmap_abort_update_v(struct nilfs_bmap *,
+                               union nilfs_bmap_ptr_req *,
+                               union nilfs_bmap_ptr_req *);
 
 void nilfs_bmap_add_blocks(const struct nilfs_bmap *, int);
 void nilfs_bmap_sub_blocks(const struct nilfs_bmap *, int);