nilfs2: add update functions of virtual block address to dat

This is a preparation for the successive cleanup ("nilfs2: allow btree
to directly call dat operations").

This adds functions bundling a few operations to change an entry of
virtual block address on the dat file.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/bmap.c

@@ -533,38 +533,25 @@ int nilfs_bmap_prepare_update_v(struct nilfs_bmap *bmap,
 				union nilfs_bmap_ptr_req *oldreq,
 				union nilfs_bmap_ptr_req *newreq)
 {
-	struct inode *dat = nilfs_bmap_get_dat(bmap);
-	int ret;
-
-	ret = nilfs_dat_prepare_end(dat, &oldreq->bpr_req);
-	if (ret < 0)
-		return ret;
-	ret = nilfs_dat_prepare_alloc(dat, &newreq->bpr_req);
-	if (ret < 0)
-		nilfs_dat_abort_end(dat, &oldreq->bpr_req);
-
-	return ret;
+	return nilfs_dat_prepare_update(nilfs_bmap_get_dat(bmap),
+					&oldreq->bpr_req, &newreq->bpr_req);
 }
 
 void nilfs_bmap_commit_update_v(struct nilfs_bmap *bmap,
 				union nilfs_bmap_ptr_req *oldreq,
 				union nilfs_bmap_ptr_req *newreq)
 {
-	struct inode *dat = nilfs_bmap_get_dat(bmap);
-
-	nilfs_dat_commit_end(dat, &oldreq->bpr_req,
+	nilfs_dat_commit_update(nilfs_bmap_get_dat(bmap),
+				&oldreq->bpr_req, &newreq->bpr_req,
 				bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
-	nilfs_dat_commit_alloc(dat, &newreq->bpr_req);
 }
 
 void nilfs_bmap_abort_update_v(struct nilfs_bmap *bmap,
 			       union nilfs_bmap_ptr_req *oldreq,
 			       union nilfs_bmap_ptr_req *newreq)
 {
-	struct inode *dat = nilfs_bmap_get_dat(bmap);
-
-	nilfs_dat_abort_end(dat, &oldreq->bpr_req);
-	nilfs_dat_abort_alloc(dat, &newreq->bpr_req);
+	nilfs_dat_abort_update(nilfs_bmap_get_dat(bmap),
+			       &oldreq->bpr_req, &newreq->bpr_req);
 }
 
 static struct lock_class_key nilfs_bmap_dat_lock_key;

fs/nilfs2/dat.c

@@ -211,6 +211,37 @@ void nilfs_dat_abort_end(struct inode *dat, struct nilfs_palloc_req *req)
 	nilfs_dat_abort_entry(dat, req);
 }
 
+int nilfs_dat_prepare_update(struct inode *dat,
+			     struct nilfs_palloc_req *oldreq,
+			     struct nilfs_palloc_req *newreq)
+{
+	int ret;
+
+	ret = nilfs_dat_prepare_end(dat, oldreq);
+	if (!ret) {
+		ret = nilfs_dat_prepare_alloc(dat, newreq);
+		if (ret < 0)
+			nilfs_dat_abort_end(dat, oldreq);
+	}
+	return ret;
+}
+
+void nilfs_dat_commit_update(struct inode *dat,
+			     struct nilfs_palloc_req *oldreq,
+			     struct nilfs_palloc_req *newreq, int dead)
+{
+	nilfs_dat_commit_end(dat, oldreq, dead);
+	nilfs_dat_commit_alloc(dat, newreq);
+}
+
+void nilfs_dat_abort_update(struct inode *dat,
+			    struct nilfs_palloc_req *oldreq,
+			    struct nilfs_palloc_req *newreq)
+{
+	nilfs_dat_abort_end(dat, oldreq);
+	nilfs_dat_abort_alloc(dat, newreq);
+}
+
 /**
  * nilfs_dat_mark_dirty -
  * @dat: DAT file inode

fs/nilfs2/dat.h

@@ -41,6 +41,12 @@ void nilfs_dat_commit_start(struct inode *, struct nilfs_palloc_req *,
 int nilfs_dat_prepare_end(struct inode *, struct nilfs_palloc_req *);
 void nilfs_dat_commit_end(struct inode *, struct nilfs_palloc_req *, int);
 void nilfs_dat_abort_end(struct inode *, struct nilfs_palloc_req *);
+int nilfs_dat_prepare_update(struct inode *, struct nilfs_palloc_req *,
+			     struct nilfs_palloc_req *);
+void nilfs_dat_commit_update(struct inode *, struct nilfs_palloc_req *,
+			     struct nilfs_palloc_req *, int);
+void nilfs_dat_abort_update(struct inode *, struct nilfs_palloc_req *,
+			    struct nilfs_palloc_req *);
 
 int nilfs_dat_mark_dirty(struct inode *, __u64);
 int nilfs_dat_freev(struct inode *, __u64 *, size_t);