nilfs2: separate function for creating new btree node block

Adds a separate routine for creating a btree node block.  This is a
preparation to reduce the depth of function calls during submitting
btree node buffer.

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

2 files changed, 28 insertions, 0 deletions

diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index 84c25382f8e3..fc3e4bdb62ae 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -68,6 +68,32 @@ void nilfs_btnode_cache_clear(struct address_space *btnc)
         truncate_inode_pages(btnc, 0);
 }
 
+struct buffer_head *
+nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
+{
+        struct inode *inode = NILFS_BTNC_I(btnc);
+        struct buffer_head *bh;
+
+        bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
+        if (unlikely(!bh))
+                return NULL;
+
+        if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
+                     buffer_dirty(bh))) {
+                brelse(bh);
+                BUG();
+        }
+        memset(bh->b_data, 0, 1 << inode->i_blkbits);
+        bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
+        bh->b_blocknr = blocknr;
+        set_buffer_mapped(bh);
+        set_buffer_uptodate(bh);
+
+        unlock_page(bh->b_page);
+        page_cache_release(bh->b_page);
+        return bh;
+}
+
 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
                               sector_t pblocknr, struct buffer_head **pbh,
                               int newblk)
diff --git a/fs/nilfs2/btnode.h b/fs/nilfs2/btnode.h
index 3e2275172ed6..c53644c0cf0f 100644
--- a/fs/nilfs2/btnode.h
+++ b/fs/nilfs2/btnode.h
@@ -40,6 +40,8 @@ struct nilfs_btnode_chkey_ctxt {
 void nilfs_btnode_cache_init_once(struct address_space *);
 void nilfs_btnode_cache_init(struct address_space *, struct backing_dev_info *);
 void nilfs_btnode_cache_clear(struct address_space *);
+struct buffer_head *nilfs_btnode_create_block(struct address_space *btnc,
+                                              __u64 blocknr);
 int nilfs_btnode_submit_block(struct address_space *, __u64, sector_t,
                               struct buffer_head **, int);
 int nilfs_btnode_get(struct address_space *, __u64, sector_t,