Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2: (21 commits)
  fs/Kconfig: move nilfs2 outside misc filesystems
  nilfs2: convert nilfs_bmap_lookup to an inline function
  nilfs2: allow btree code to directly call dat operations
  nilfs2: add update functions of virtual block address to dat
  nilfs2: remove individual gfp constants for each metadata file
  nilfs2: stop zero-fill of btree path just before free it
  nilfs2: remove unused btree argument from btree functions
  nilfs2: remove nilfs_dat_abort_start and nilfs_dat_abort_free
  nilfs2: shorten freeze period due to GC in write operation v3
  nilfs2: add more check routines in mount process
  nilfs2: An unassigned variable is assigned to a never used structure member
  nilfs2: use GFP_NOIO for bio_alloc instead of GFP_NOWAIT
  nilfs2: stop using periodic write_super callback
  nilfs2: clean up nilfs_write_super
  nilfs2: fix disorder of nilfs_write_super in nilfs_sync_fs
  nilfs2: remove redundant super block commit
  nilfs2: implement nilfs_show_options to display mount options in /proc/mounts
  nilfs2: always lookup disk block address before reading metadata block
  nilfs2: use semaphore to protect pointer to a writable FS-instance
  nilfs2: fix format string compile warning (ino_t)
  ...

22 files changed, 567 insertions, 759 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 0e7da7bb5d9..455aa207e67 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -43,6 +43,7 @@ source "fs/xfs/Kconfig"
 source "fs/gfs2/Kconfig"
 source "fs/ocfs2/Kconfig"
 source "fs/btrfs/Kconfig"
+source "fs/nilfs2/Kconfig"
 
 endif # BLOCK
 
@@ -186,7 +187,6 @@ source "fs/romfs/Kconfig"
 source "fs/sysv/Kconfig"
 source "fs/ufs/Kconfig"
 source "fs/exofs/Kconfig"
-source "fs/nilfs2/Kconfig"
 
 endif # MISC_FILESYSTEMS
 
diff --git a/fs/nilfs2/Kconfig b/fs/nilfs2/Kconfig
index 72da095d400..251da07b2a1 100644
--- a/fs/nilfs2/Kconfig
+++ b/fs/nilfs2/Kconfig
@@ -1,6 +1,6 @@
 config NILFS2_FS
 	tristate "NILFS2 file system support (EXPERIMENTAL)"
-	depends on BLOCK && EXPERIMENTAL
+	depends on EXPERIMENTAL
 	select CRC32
 	help
 	  NILFS2 is a log-structured file system (LFS) supporting continuous
diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
index 99d58a028b9..08834df6ec6 100644
--- a/fs/nilfs2/bmap.c
+++ b/fs/nilfs2/bmap.c
@@ -36,6 +36,26 @@ struct inode *nilfs_bmap_get_dat(const struct nilfs_bmap *bmap)
 	return nilfs_dat_inode(NILFS_I_NILFS(bmap->b_inode));
 }
 
+/**
+ * nilfs_bmap_lookup_at_level - find a data block or node block
+ * @bmap: bmap
+ * @key: key
+ * @level: level
+ * @ptrp: place to store the value associated to @key
+ *
+ * Description: nilfs_bmap_lookup_at_level() finds a record whose key
+ * matches @key in the block at @level of the bmap.
+ *
+ * Return Value: On success, 0 is returned and the record associated with @key
+ * is stored in the place pointed by @ptrp. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - A record associated with @key does not exist.
+ */
 int nilfs_bmap_lookup_at_level(struct nilfs_bmap *bmap, __u64 key, int level,
 			       __u64 *ptrp)
 {
@@ -69,39 +89,6 @@ int nilfs_bmap_lookup_contig(struct nilfs_bmap *bmap, __u64 key, __u64 *ptrp,
 	return ret;
 }
 
-/**
- * nilfs_bmap_lookup - find a record
- * @bmap: bmap
- * @key: key
- * @recp: pointer to record
- *
- * Description: nilfs_bmap_lookup() finds a record whose key matches @key in
- * @bmap.
- *
- * Return Value: On success, 0 is returned and the record associated with @key
- * is stored in the place pointed by @recp. On error, one of the following
- * negative error codes is returned.
- *
- * %-EIO - I/O error.
- *
- * %-ENOMEM - Insufficient amount of memory available.
- *
- * %-ENOENT - A record associated with @key does not exist.
- */
-int nilfs_bmap_lookup(struct nilfs_bmap *bmap,
-		      unsigned long key,
-		      unsigned long *recp)
-{
-	__u64 ptr;
-	int ret;
-
-	/* XXX: use macro for level 1 */
-	ret = nilfs_bmap_lookup_at_level(bmap, key, 1, &ptr);
-	if (recp != NULL)
-		*recp = ptr;
-	return ret;
-}
-
 static int nilfs_bmap_do_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
 {
 	__u64 keys[NILFS_BMAP_SMALL_HIGH + 1];
@@ -469,104 +456,6 @@ __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
 		(entries_per_group / NILFS_BMAP_GROUP_DIV);
 }
 
-int nilfs_bmap_prepare_alloc_v(struct nilfs_bmap *bmap,
-				 union nilfs_bmap_ptr_req *req)
-{
-	return nilfs_dat_prepare_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
-}
-
-void nilfs_bmap_commit_alloc_v(struct nilfs_bmap *bmap,
-				 union nilfs_bmap_ptr_req *req)
-{
-	nilfs_dat_commit_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
-}
-
-void nilfs_bmap_abort_alloc_v(struct nilfs_bmap *bmap,
-			      union nilfs_bmap_ptr_req *req)
-{
-	nilfs_dat_abort_alloc(nilfs_bmap_get_dat(bmap), &req->bpr_req);
-}
-
-int nilfs_bmap_start_v(struct nilfs_bmap *bmap, union nilfs_bmap_ptr_req *req,
-		       sector_t blocknr)
-{
-	struct inode *dat = nilfs_bmap_get_dat(bmap);
-	int ret;
-
-	ret = nilfs_dat_prepare_start(dat, &req->bpr_req);
-	if (likely(!ret))
-		nilfs_dat_commit_start(dat, &req->bpr_req, blocknr);
-	return ret;
-}
-
-int nilfs_bmap_prepare_end_v(struct nilfs_bmap *bmap,
-			     union nilfs_bmap_ptr_req *req)
-{
-	return nilfs_dat_prepare_end(nilfs_bmap_get_dat(bmap), &req->bpr_req);
-}
-
-void nilfs_bmap_commit_end_v(struct nilfs_bmap *bmap,
-			     union nilfs_bmap_ptr_req *req)
-{
-	nilfs_dat_commit_end(nilfs_bmap_get_dat(bmap), &req->bpr_req,
-			     bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
-}
-
-void nilfs_bmap_abort_end_v(struct nilfs_bmap *bmap,
-			    union nilfs_bmap_ptr_req *req)
-{
-	nilfs_dat_abort_end(nilfs_bmap_get_dat(bmap), &req->bpr_req);
-}
-
-int nilfs_bmap_move_v(const struct nilfs_bmap *bmap, __u64 vblocknr,
-		      sector_t blocknr)
-{
-	return nilfs_dat_move(nilfs_bmap_get_dat(bmap), vblocknr, blocknr);
-}
-
-int nilfs_bmap_mark_dirty(const struct nilfs_bmap *bmap, __u64 vblocknr)
-{
-	return nilfs_dat_mark_dirty(nilfs_bmap_get_dat(bmap), vblocknr);
-}
-
-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;
-}
-
-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,
-			     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);
-}
-
 static struct lock_class_key nilfs_bmap_dat_lock_key;
 static struct lock_class_key nilfs_bmap_mdt_lock_key;
 
diff --git a/fs/nilfs2/bmap.h b/fs/nilfs2/bmap.h
index b2890cdcef1..9980d7dbab9 100644
--- a/fs/nilfs2/bmap.h
+++ b/fs/nilfs2/bmap.h
@@ -28,6 +28,7 @@
 #include <linux/buffer_head.h>
 #include <linux/nilfs2_fs.h>
 #include "alloc.h"
+#include "dat.h"
 
 #define NILFS_BMAP_INVALID_PTR	0
 
@@ -141,7 +142,6 @@ struct nilfs_bmap {
 int nilfs_bmap_test_and_clear_dirty(struct nilfs_bmap *);
 int nilfs_bmap_read(struct nilfs_bmap *, struct nilfs_inode *);
 void nilfs_bmap_write(struct nilfs_bmap *, struct nilfs_inode *);
-int nilfs_bmap_lookup(struct nilfs_bmap *, unsigned long, unsigned long *);
 int nilfs_bmap_lookup_contig(struct nilfs_bmap *, __u64, __u64 *, unsigned);
 int nilfs_bmap_insert(struct nilfs_bmap *, unsigned long, unsigned long);
 int nilfs_bmap_delete(struct nilfs_bmap *, unsigned long);
@@ -160,90 +160,76 @@ void nilfs_bmap_init_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
 void nilfs_bmap_commit_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
 
 
+static inline int nilfs_bmap_lookup(struct nilfs_bmap *bmap, __u64 key,
+				    __u64 *ptr)
+{
+	return nilfs_bmap_lookup_at_level(bmap, key, 1, ptr);
+}
+
 /*
  * Internal use only
  */
 struct inode *nilfs_bmap_get_dat(const struct nilfs_bmap *);
-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)
+					       union nilfs_bmap_ptr_req *req,
+					       struct inode *dat)
 {
-	if (NILFS_BMAP_USE_VBN(bmap))
-		return nilfs_bmap_prepare_alloc_v(bmap, req);
+	if (dat)
+		return nilfs_dat_prepare_alloc(dat, &req->bpr_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)
+					       union nilfs_bmap_ptr_req *req,
+					       struct inode *dat)
 {
-	if (NILFS_BMAP_USE_VBN(bmap))
-		nilfs_bmap_commit_alloc_v(bmap, req);
+	if (dat)
+		nilfs_dat_commit_alloc(dat, &req->bpr_req);
 }
 
 static inline void nilfs_bmap_abort_alloc_ptr(struct nilfs_bmap *bmap,
-					      union nilfs_bmap_ptr_req *req)
+					      union nilfs_bmap_ptr_req *req,
+					      struct inode *dat)
 {
-	if (NILFS_BMAP_USE_VBN(bmap))
-		nilfs_bmap_abort_alloc_v(bmap, req);
+	if (dat)
+		nilfs_dat_abort_alloc(dat, &req->bpr_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)
+					     union nilfs_bmap_ptr_req *req,
+					     struct inode *dat)
 {
-	return NILFS_BMAP_USE_VBN(bmap) ?
-		nilfs_bmap_prepare_end_v(bmap, req) : 0;
+	return dat ? nilfs_dat_prepare_end(dat, &req->bpr_req) : 0;
 }
 
 static inline void nilfs_bmap_commit_end_ptr(struct nilfs_bmap *bmap,
-					     union nilfs_bmap_ptr_req *req)
+					     union nilfs_bmap_ptr_req *req,
+					     struct inode *dat)
 {
-	if (NILFS_BMAP_USE_VBN(bmap))
-		nilfs_bmap_commit_end_v(bmap, req);
+	if (dat)
+		nilfs_dat_commit_end(dat, &req->bpr_req,
+				     bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
 }
 
 static inline void nilfs_bmap_abort_end_ptr(struct nilfs_bmap *bmap,
-					    union nilfs_bmap_ptr_req *req)
+					    union nilfs_bmap_ptr_req *req,
+					    struct inode *dat)
 {
-	if (NILFS_BMAP_USE_VBN(bmap))
-		nilfs_bmap_abort_end_v(bmap, req);
+	if (dat)
+		nilfs_dat_abort_end(dat, &req->bpr_req);
 }
 
-int nilfs_bmap_start_v(struct nilfs_bmap *, union nilfs_bmap_ptr_req *,
-		       sector_t);
-int nilfs_bmap_move_v(const struct nilfs_bmap *, __u64, sector_t);
-int nilfs_bmap_mark_dirty(const struct nilfs_bmap *, __u64);
-
-
 __u64 nilfs_bmap_data_get_key(const struct nilfs_bmap *,
 			      const struct buffer_head *);
 
 __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_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);
 
diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
index aa412724b64..e25b507a474 100644
--- a/fs/nilfs2/btree.c
+++ b/fs/nilfs2/btree.c
@@ -71,21 +71,17 @@ void nilfs_btree_path_cache_destroy(void)
 	kmem_cache_destroy(nilfs_btree_path_cache);
 }
 
-static inline struct nilfs_btree_path *
-nilfs_btree_alloc_path(const struct nilfs_btree *btree)
+static inline struct nilfs_btree_path *nilfs_btree_alloc_path(void)
 {
-	return (struct nilfs_btree_path *)
-		kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
+	return kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
 }
 
-static inline void nilfs_btree_free_path(const struct nilfs_btree *btree,
-					 struct nilfs_btree_path *path)
+static inline void nilfs_btree_free_path(struct nilfs_btree_path *path)
 {
 	kmem_cache_free(nilfs_btree_path_cache, path);
 }
 
-static void nilfs_btree_init_path(const struct nilfs_btree *btree,
-				  struct nilfs_btree_path *path)
+static void nilfs_btree_init_path(struct nilfs_btree_path *path)
 {
 	int level;
 
@@ -101,26 +97,13 @@ static void nilfs_btree_init_path(const struct nilfs_btree *btree,
 	}
 }
 
-static void nilfs_btree_clear_path(const struct nilfs_btree *btree,
-				   struct nilfs_btree_path *path)
+static void nilfs_btree_release_path(struct nilfs_btree_path *path)
 {
 	int level;
 
-	for (level = NILFS_BTREE_LEVEL_DATA;
-	     level < NILFS_BTREE_LEVEL_MAX;
-	     level++) {
-		if (path[level].bp_bh != NULL) {
-			brelse(path[level].bp_bh);
-			path[level].bp_bh = NULL;
-		}
-		/* sib_bh is released or deleted by prepare or commit
-		 * operations. */
-		path[level].bp_sib_bh = NULL;
-		path[level].bp_index = 0;
-		path[level].bp_oldreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
-		path[level].bp_newreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
-		path[level].bp_op = NULL;
-	}
+	for (level = NILFS_BTREE_LEVEL_DATA; level < NILFS_BTREE_LEVEL_MAX;
+	     level++)
+		brelse(path[level].bp_bh);
 }
 
 /*
@@ -148,129 +131,110 @@ static int nilfs_btree_get_new_block(const struct nilfs_btree *btree,
 }
 
 static inline int
-nilfs_btree_node_get_flags(const struct nilfs_btree *btree,
-			   const struct nilfs_btree_node *node)
+nilfs_btree_node_get_flags(const struct nilfs_btree_node *node)
 {
 	return node->bn_flags;
 }
 
 static inline void
-nilfs_btree_node_set_flags(struct nilfs_btree *btree,
-			   struct nilfs_btree_node *node,
-			   int flags)
+nilfs_btree_node_set_flags(struct nilfs_btree_node *node, int flags)
 {
 	node->bn_flags = flags;
 }
 
-static inline int nilfs_btree_node_root(const struct nilfs_btree *btree,
-					const struct nilfs_btree_node *node)
+static inline int nilfs_btree_node_root(const struct nilfs_btree_node *node)
 {
-	return nilfs_btree_node_get_flags(btree, node) & NILFS_BTREE_NODE_ROOT;
+	return nilfs_btree_node_get_flags(node) & NILFS_BTREE_NODE_ROOT;
 }
 
 static inline int
-nilfs_btree_node_get_level(const struct nilfs_btree *btree,
-			   const struct nilfs_btree_node *node)
+nilfs_btree_node_get_level(const struct nilfs_btree_node *node)
 {
 	return node->bn_level;
 }
 
 static inline void
-nilfs_btree_node_set_level(struct nilfs_btree *btree,
-			   struct nilfs_btree_node *node,
-			   int level)
+nilfs_btree_node_set_level(struct nilfs_btree_node *node, int level)
 {
 	node->bn_level = level;
 }
 
 static inline int
-nilfs_btree_node_get_nchildren(const struct nilfs_btree *btree,
-			       const struct nilfs_btree_node *node)
+nilfs_btree_node_get_nchildren(const struct nilfs_btree_node *node)
 {
 	return le16_to_cpu(node->bn_nchildren);
 }
 
 static inline void
-nilfs_btree_node_set_nchildren(struct nilfs_btree *btree,
-			       struct nilfs_btree_node *node,
-			       int nchildren)
+nilfs_btree_node_set_nchildren(struct nilfs_btree_node *node, int nchildren)
 {
 	node->bn_nchildren = cpu_to_le16(nchildren);
 }
 
-static inline int
-nilfs_btree_node_size(const struct nilfs_btree *btree)
+static inline int nilfs_btree_node_size(const struct nilfs_btree *btree)
 {
 	return 1 << btree->bt_bmap.b_inode->i_blkbits;
 }
 
 static inline int
-nilfs_btree_node_nchildren_min(const struct nilfs_btree *btree,
-			       const struct nilfs_btree_node *node)
+nilfs_btree_node_nchildren_min(const struct nilfs_btree_node *node,
+			       const struct nilfs_btree *btree)
 {
-	return nilfs_btree_node_root(btree, node) ?
+	return nilfs_btree_node_root(node) ?
 		NILFS_BTREE_ROOT_NCHILDREN_MIN :
 		NILFS_BTREE_NODE_NCHILDREN_MIN(nilfs_btree_node_size(btree));
 }
 
 static inline int
-nilfs_btree_node_nchildren_max(const struct nilfs_btree *btree,
-			       const struct nilfs_btree_node *node)
+nilfs_btree_node_nchildren_max(const struct nilfs_btree_node *node,
+			       const struct nilfs_btree *btree)
 {
-	return nilfs_btree_node_root(btree, node) ?
+	return nilfs_btree_node_root(node) ?
 		NILFS_BTREE_ROOT_NCHILDREN_MAX :
 		NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(btree));
 }
 
 static inline __le64 *
-nilfs_btree_node_dkeys(const struct nilfs_btree *btree,
-		       const struct nilfs_btree_node *node)
+nilfs_btree_node_dkeys(const struct nilfs_btree_node *node)
 {
 	return (__le64 *)((char *)(node + 1) +
-			  (nilfs_btree_node_root(btree, node) ?
+			  (nilfs_btree_node_root(node) ?
 			   0 : NILFS_BTREE_NODE_EXTRA_PAD_SIZE));
 }
 
 static inline __le64 *
-nilfs_btree_node_dptrs(const struct nilfs_btree *btree,
-		       const struct nilfs_btree_node *node)
+nilfs_btree_node_dptrs(const struct nilfs_btree_node *node,
+		       const struct nilfs_btree *btree)
 {
-	return (__le64 *)(nilfs_btree_node_dkeys(btree, node) +
-			  nilfs_btree_node_nchildren_max(btree, node));
+	return (__le64 *)(nilfs_btree_node_dkeys(node) +
+			  nilfs_btree_node_nchildren_max(node, btree));
 }
 
 static inline __u64
-nilfs_btree_node_get_key(const struct nilfs_btree *btree,
-			 const struct nilfs_btree_node *node, int index)
+nilfs_btree_node_get_key(const struct nilfs_btree_node *node, int index)
 {
-	return nilfs_bmap_dkey_to_key(*(nilfs_btree_node_dkeys(btree, node) +
-					index));
+	return nilfs_bmap_dkey_to_key(*(nilfs_btree_node_dkeys(node) + index));
 }
 
 static inline void
-nilfs_btree_node_set_key(struct nilfs_btree *btree,
-			 struct nilfs_btree_node *node, int index, __u64 key)
+nilfs_btree_node_set_key(struct nilfs_btree_node *node, int index, __u64 key)
 {
-	*(nilfs_btree_node_dkeys(btree, node) + index) =
-		nilfs_bmap_key_to_dkey(key);
+	*(nilfs_btree_node_dkeys(node) + index) = nilfs_bmap_key_to_dkey(key);
 }
 
 static inline __u64
 nilfs_btree_node_get_ptr(const struct nilfs_btree *btree,
-			 const struct nilfs_btree_node *node,
-			 int index)
+			 const struct nilfs_btree_node *node, int index)
 {
-	return nilfs_bmap_dptr_to_ptr(*(nilfs_btree_node_dptrs(btree, node) +
+	return nilfs_bmap_dptr_to_ptr(*(nilfs_btree_node_dptrs(node, btree) +
 					index));
 }
 
 static inline void
 nilfs_btree_node_set_ptr(struct nilfs_btree *btree,
-			 struct nilfs_btree_node *node,
-			 int index,
-			 __u64 ptr)
+			 struct nilfs_btree_node *node, int index, __u64 ptr)
 {
-	*(nilfs_btree_node_dptrs(btree, node) + index) =
+	*(nilfs_btree_node_dptrs(node, btree) + index) =
 		nilfs_bmap_ptr_to_dptr(ptr);
 }
 
@@ -283,12 +247,12 @@ static void nilfs_btree_node_init(struct nilfs_btree *btree,
 	__le64 *dptrs;
 	int i;
 
-	nilfs_btree_node_set_flags(btree, node, flags);
-	nilfs_btree_node_set_level(btree, node, level);
-	nilfs_btree_node_set_nchildren(btree, node, nchildren);
+	nilfs_btree_node_set_flags(node, flags);
+	nilfs_btree_node_set_level(node, level);
+	nilfs_btree_node_set_nchildren(node, nchildren);
 
-	dkeys = nilfs_btree_node_dkeys(btree, node);
-	dptrs = nilfs_btree_node_dptrs(btree, node);
+	dkeys = nilfs_btree_node_dkeys(node);
+	dptrs = nilfs_btree_node_dptrs(node, btree);
 	for (i = 0; i < nchildren; i++) {
 		dkeys[i] = nilfs_bmap_key_to_dkey(keys[i]);
 		dptrs[i] = nilfs_bmap_ptr_to_dptr(ptrs[i]);
@@ -305,13 +269,13 @@ static void nilfs_btree_node_move_left(struct nilfs_btree *btree,
 	__le64 *ldptrs, *rdptrs;
 	int lnchildren, rnchildren;
 
-	ldkeys = nilfs_btree_node_dkeys(btree, left);
-	ldptrs = nilfs_btree_node_dptrs(btree, left);
-	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+	ldkeys = nilfs_btree_node_dkeys(left);
+	ldptrs = nilfs_btree_node_dptrs(left, btree);
+	lnchildren = nilfs_btree_node_get_nchildren(left);
 
-	rdkeys = nilfs_btree_node_dkeys(btree, right);
-	rdptrs = nilfs_btree_node_dptrs(btree, right);
-	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+	rdkeys = nilfs_btree_node_dkeys(right);
+	rdptrs = nilfs_btree_node_dptrs(right, btree);
+	rnchildren = nilfs_btree_node_get_nchildren(right);
 
 	memcpy(ldkeys + lnchildren, rdkeys, n * sizeof(*rdkeys));
 	memcpy(ldptrs + lnchildren, rdptrs, n * sizeof(*rdptrs));
@@ -320,8 +284,8 @@ static void nilfs_btree_node_move_left(struct nilfs_btree *btree,
 
 	lnchildren += n;
 	rnchildren -= n;
-	nilfs_btree_node_set_nchildren(btree, left, lnchildren);
-	nilfs_btree_node_set_nchildren(btree, right, rnchildren);
+	nilfs_btree_node_set_nchildren(left, lnchildren);
+	nilfs_btree_node_set_nchildren(right, rnchildren);
 }
 
 /* Assume that the buffer heads corresponding to left and right are locked. */
@@ -334,13 +298,13 @@ static void nilfs_btree_node_move_right(struct nilfs_btree *btree,
 	__le64 *ldptrs, *rdptrs;
 	int lnchildren, rnchildren;
 
-	ldkeys = nilfs_btree_node_dkeys(btree, left);
-	ldptrs = nilfs_btree_node_dptrs(btree, left);
-	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+	ldkeys = nilfs_btree_node_dkeys(left);
+	ldptrs = nilfs_btree_node_dptrs(left, btree);
+	lnchildren = nilfs_btree_node_get_nchildren(left);
 
-	rdkeys = nilfs_btree_node_dkeys(btree, right);
-	rdptrs = nilfs_btree_node_dptrs(btree, right);
-	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+	rdkeys = nilfs_btree_node_dkeys(right);
+	rdptrs = nilfs_btree_node_dptrs(right, btree);
+	rnchildren = nilfs_btree_node_get_nchildren(right);
 
 	memmove(rdkeys + n, rdkeys, rnchildren * sizeof(*rdkeys));
 	memmove(rdptrs + n, rdptrs, rnchildren * sizeof(*rdptrs));
@@ -349,8 +313,8 @@ static void nilfs_btree_node_move_right(struct nilfs_btree *btree,
 
 	lnchildren -= n;
 	rnchildren += n;
-	nilfs_btree_node_set_nchildren(btree, left, lnchildren);
-	nilfs_btree_node_set_nchildren(btree, right, rnchildren);
+	nilfs_btree_node_set_nchildren(left, lnchildren);
+	nilfs_btree_node_set_nchildren(right, rnchildren);
 }
 
 /* Assume that the buffer head corresponding to node is locked. */
@@ -362,9 +326,9 @@ static void nilfs_btree_node_insert(struct nilfs_btree *btree,
 	__le64 *dptrs;
 	int nchildren;
 
-	dkeys = nilfs_btree_node_dkeys(btree, node);
-	dptrs = nilfs_btree_node_dptrs(btree, node);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	dkeys = nilfs_btree_node_dkeys(node);
+	dptrs = nilfs_btree_node_dptrs(node, btree);
+	nchildren = nilfs_btree_node_get_nchildren(node);
 	if (index < nchildren) {
 		memmove(dkeys + index + 1, dkeys + index,
 			(nchildren - index) * sizeof(*dkeys));
@@ -374,7 +338,7 @@ static void nilfs_btree_node_insert(struct nilfs_btree *btree,
 	dkeys[index] = nilfs_bmap_key_to_dkey(key);
 	dptrs[index] = nilfs_bmap_ptr_to_dptr(ptr);
 	nchildren++;
-	nilfs_btree_node_set_nchildren(btree, node, nchildren);
+	nilfs_btree_node_set_nchildren(node, nchildren);
 }
 
 /* Assume that the buffer head corresponding to node is locked. */
@@ -388,11 +352,11 @@ static void nilfs_btree_node_delete(struct nilfs_btree *btree,
 	__le64 *dptrs;
 	int nchildren;
 
-	dkeys = nilfs_btree_node_dkeys(btree, node);
-	dptrs = nilfs_btree_node_dptrs(btree, node);
+	dkeys = nilfs_btree_node_dkeys(node);
+	dptrs = nilfs_btree_node_dptrs(node, btree);
 	key = nilfs_bmap_dkey_to_key(dkeys[index]);
 	ptr = nilfs_bmap_dptr_to_ptr(dptrs[index]);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	nchildren = nilfs_btree_node_get_nchildren(node);
 	if (keyp != NULL)
 		*keyp = key;
 	if (ptrp != NULL)
@@ -405,11 +369,10 @@ static void nilfs_btree_node_delete(struct nilfs_btree *btree,
 			(nchildren - index - 1) * sizeof(*dptrs));
 	}
 	nchildren--;
-	nilfs_btree_node_set_nchildren(btree, node, nchildren);
+	nilfs_btree_node_set_nchildren(node, nchildren);
 }
 
-static int nilfs_btree_node_lookup(const struct nilfs_btree *btree,
-				   const struct nilfs_btree_node *node,
+static int nilfs_btree_node_lookup(const struct nilfs_btree_node *node,
 				   __u64 key, int *indexp)
 {
 	__u64 nkey;
@@ -417,12 +380,12 @@ static int nilfs_btree_node_lookup(const struct nilfs_btree *btree,
 
 	/* binary search */
 	low = 0;
-	high = nilfs_btree_node_get_nchildren(btree, node) - 1;
+	high = nilfs_btree_node_get_nchildren(node) - 1;
 	index = 0;
 	s = 0;
 	while (low <= high) {
 		index = (low + high) / 2;
-		nkey = nilfs_btree_node_get_key(btree, node, index);
+		nkey = nilfs_btree_node_get_key(node, index);
 		if (nkey == key) {
 			s = 0;
 			goto out;
@@ -436,9 +399,8 @@ static int nilfs_btree_node_lookup(const struct nilfs_btree *btree,
 	}
 
 	/* adjust index */
-	if (nilfs_btree_node_get_level(btree, node) >
-	    NILFS_BTREE_LEVEL_NODE_MIN) {
-		if ((s > 0) && (index > 0))
+	if (nilfs_btree_node_get_level(node) > NILFS_BTREE_LEVEL_NODE_MIN) {
+		if (s > 0 && index > 0)
 			index--;
 	} else if (s < 0)
 		index++;
@@ -456,25 +418,20 @@ nilfs_btree_get_root(const struct nilfs_btree *btree)
 }
 
 static inline struct nilfs_btree_node *
-nilfs_btree_get_nonroot_node(const struct nilfs_btree *btree,
-			     const struct nilfs_btree_path *path,
-			     int level)
+nilfs_btree_get_nonroot_node(const struct nilfs_btree_path *path, int level)
 {
 	return (struct nilfs_btree_node *)path[level].bp_bh->b_data;
 }
 
 static inline struct nilfs_btree_node *
-nilfs_btree_get_sib_node(const struct nilfs_btree *btree,
-			 const struct nilfs_btree_path *path,
-			 int level)
+nilfs_btree_get_sib_node(const struct nilfs_btree_path *path, int level)
 {
 	return (struct nilfs_btree_node *)path[level].bp_sib_bh->b_data;
 }
 
 static inline int nilfs_btree_height(const struct nilfs_btree *btree)
 {
-	return nilfs_btree_node_get_level(btree, nilfs_btree_get_root(btree))
-		+ 1;
+	return nilfs_btree_node_get_level(nilfs_btree_get_root(btree)) + 1;
 }
 
 static inline struct nilfs_btree_node *
@@ -484,7 +441,7 @@ nilfs_btree_get_node(const struct nilfs_btree *btree,
 {
 	return (level == nilfs_btree_height(btree) - 1) ?
 		nilfs_btree_get_root(btree) :
-		nilfs_btree_get_nonroot_node(btree, path, level);
+		nilfs_btree_get_nonroot_node(path, level);
 }
 
 static int nilfs_btree_do_lookup(const struct nilfs_btree *btree,
@@ -496,12 +453,11 @@ static int nilfs_btree_do_lookup(const struct nilfs_btree *btree,
 	int level, index, found, ret;
 
 	node = nilfs_btree_get_root(btree);
-	level = nilfs_btree_node_get_level(btree, node);
-	if ((level < minlevel) ||
-	    (nilfs_btree_node_get_nchildren(btree, node) <= 0))
+	level = nilfs_btree_node_get_level(node);
+	if (level < minlevel || nilfs_btree_node_get_nchildren(node) <= 0)
 		return -ENOENT;
 
-	found = nilfs_btree_node_lookup(btree, node, key, &index);
+	found = nilfs_btree_node_lookup(node, key, &index);
 	ptr = nilfs_btree_node_get_ptr(btree, node, index);
 	path[level].bp_bh = NULL;
 	path[level].bp_index = index;
@@ -510,14 +466,13 @@ static int nilfs_btree_do_lookup(const struct nilfs_btree *btree,
 		ret = nilfs_btree_get_block(btree, ptr, &path[level].bp_bh);
 		if (ret < 0)
 			return ret;
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
-		BUG_ON(level != nilfs_btree_node_get_level(btree, node));
+		node = nilfs_btree_get_nonroot_node(path, level);
+		BUG_ON(level != nilfs_btree_node_get_level(node));
 		if (!found)
-			found = nilfs_btree_node_lookup(btree, node, key,
-							&index);
+			found = nilfs_btree_node_lookup(node, key, &index);
 		else
 			index = 0;
-		if (index < nilfs_btree_node_nchildren_max(btree, node))
+		if (index < nilfs_btree_node_nchildren_max(node, btree))
 			ptr = nilfs_btree_node_get_ptr(btree, node, index);
 		else {
 			WARN_ON(found || level != NILFS_BTREE_LEVEL_NODE_MIN);
@@ -544,10 +499,10 @@ static int nilfs_btree_do_lookup_last(const struct nilfs_btree *btree,
 	int index, level, ret;
 
 	node = nilfs_btree_get_root(btree);
-	index = nilfs_btree_node_get_nchildren(btree, node) - 1;
+	index = nilfs_btree_node_get_nchildren(node) - 1;
 	if (index < 0)
 		return -ENOENT;
-	level = nilfs_btree_node_get_level(btree, node);
+	level = nilfs_btree_node_get_level(node);
 	ptr = nilfs_btree_node_get_ptr(btree, node, index);
 	path[level].bp_bh = NULL;
 	path[level].bp_index = index;
@@ -556,15 +511,15 @@ static int nilfs_btree_do_lookup_last(const struct nilfs_btree *btree,
 		ret = nilfs_btree_get_block(btree, ptr, &path[level].bp_bh);
 		if (ret < 0)
 			return ret;
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
-		BUG_ON(level != nilfs_btree_node_get_level(btree, node));
-		index = nilfs_btree_node_get_nchildren(btree, node) - 1;
+		node = nilfs_btree_get_nonroot_node(path, level);
+		BUG_ON(level != nilfs_btree_node_get_level(node));
+		index = nilfs_btree_node_get_nchildren(node) - 1;
 		ptr = nilfs_btree_node_get_ptr(btree, node, index);
 		path[level].bp_index = index;
 	}
 
 	if (keyp != NULL)
-		*keyp = nilfs_btree_node_get_key(btree, node, index);
+		*keyp = nilfs_btree_node_get_key(node, index);
 	if (ptrp != NULL)
 		*ptrp = ptr;
 
@@ -580,18 +535,18 @@ static int nilfs_btree_lookup(const struct nilfs_bmap *bmap,
 	int ret;
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level);
 
 	if (ptrp != NULL)
 		*ptrp = ptr;
 
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 
 	return ret;
 }
@@ -608,10 +563,10 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 	int level = NILFS_BTREE_LEVEL_NODE_MIN;
 	int ret, cnt, index, maxlevel;
 
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level);
 	if (ret < 0)
 		goto out;
@@ -631,8 +586,8 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 	node = nilfs_btree_get_node(btree, path, level);
 	index = path[level].bp_index + 1;
 	for (;;) {
-		while (index < nilfs_btree_node_get_nchildren(btree, node)) {
-			if (nilfs_btree_node_get_key(btree, node, index) !=
+		while (index < nilfs_btree_node_get_nchildren(node)) {
+			if (nilfs_btree_node_get_key(node, index) !=
 			    key + cnt)
 				goto end;
 			ptr2 = nilfs_btree_node_get_ptr(btree, node, index);
@@ -653,8 +608,8 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 		/* look-up right sibling node */
 		node = nilfs_btree_get_node(btree, path, level + 1);
 		index = path[level + 1].bp_index + 1;
-		if (index >= nilfs_btree_node_get_nchildren(btree, node) ||
-		    nilfs_btree_node_get_key(btree, node, index) != key + cnt)
+		if (index >= nilfs_btree_node_get_nchildren(node) ||
+		    nilfs_btree_node_get_key(node, index) != key + cnt)
 			break;
 		ptr2 = nilfs_btree_node_get_ptr(btree, node, index);
 		path[level + 1].bp_index = index;
@@ -664,7 +619,7 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 		ret = nilfs_btree_get_block(btree, ptr2, &path[level].bp_bh);
 		if (ret < 0)
 			goto out;
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		node = nilfs_btree_get_nonroot_node(path, level);
 		index = 0;
 		path[level].bp_index = index;
 	}
@@ -672,8 +627,8 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 	*ptrp = ptr;
 	ret = cnt;
  out:
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 	return ret;
 }
 
@@ -685,9 +640,7 @@ static void nilfs_btree_promote_key(struct nilfs_btree *btree,
 		do {
 			lock_buffer(path[level].bp_bh);
 			nilfs_btree_node_set_key(
-				btree,
-				nilfs_btree_get_nonroot_node(
-					btree, path, level),
+				nilfs_btree_get_nonroot_node(path, level),
 				path[level].bp_index, key);
 			if (!buffer_dirty(path[level].bp_bh))
 				nilfs_btnode_mark_dirty(path[level].bp_bh);
@@ -698,8 +651,7 @@ static void nilfs_btree_promote_key(struct nilfs_btree *btree,
 
 	/* root */
 	if (level == nilfs_btree_height(btree) - 1) {
-		nilfs_btree_node_set_key(btree,
-					 nilfs_btree_get_root(btree),
+		nilfs_btree_node_set_key(nilfs_btree_get_root(btree),
 					 path[level].bp_index, key);
 	}
 }
@@ -712,7 +664,7 @@ static void nilfs_btree_do_insert(struct nilfs_btree *btree,
 
 	if (level < nilfs_btree_height(btree) - 1) {
 		lock_buffer(path[level].bp_bh);
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		node = nilfs_btree_get_nonroot_node(path, level);
 		nilfs_btree_node_insert(btree, node, *keyp, *ptrp,
 					path[level].bp_index);
 		if (!buffer_dirty(path[level].bp_bh))
@@ -721,8 +673,8 @@ static void nilfs_btree_do_insert(struct nilfs_btree *btree,
 
 		if (path[level].bp_index == 0)
 			nilfs_btree_promote_key(btree, path, level + 1,
-						nilfs_btree_node_get_key(
-							btree, node, 0));
+						nilfs_btree_node_get_key(node,
+									 0));
 	} else {
 		node = nilfs_btree_get_root(btree);
 		nilfs_btree_node_insert(btree, node, *keyp, *ptrp,
@@ -740,10 +692,10 @@ static void nilfs_btree_carry_left(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	left = nilfs_btree_get_sib_node(btree, path, level);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
-	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	left = nilfs_btree_get_sib_node(path, level);
+	nchildren = nilfs_btree_node_get_nchildren(node);
+	lnchildren = nilfs_btree_node_get_nchildren(left);
 	move = 0;
 
 	n = (nchildren + lnchildren + 1) / 2 - lnchildren;
@@ -764,7 +716,7 @@ static void nilfs_btree_carry_left(struct nilfs_btree *btree,
 	unlock_buffer(path[level].bp_sib_bh);
 
 	nilfs_btree_promote_key(btree, path, level + 1,
-				nilfs_btree_node_get_key(btree, node, 0));
+				nilfs_btree_node_get_key(node, 0));
 
 	if (move) {
 		brelse(path[level].bp_bh);
@@ -791,10 +743,10 @@ static void nilfs_btree_carry_right(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	right = nilfs_btree_get_sib_node(btree, path, level);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
-	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	right = nilfs_btree_get_sib_node(path, level);
+	nchildren = nilfs_btree_node_get_nchildren(node);
+	rnchildren = nilfs_btree_node_get_nchildren(right);
 	move = 0;
 
 	n = (nchildren + rnchildren + 1) / 2 - rnchildren;
@@ -816,15 +768,14 @@ static void nilfs_btree_carry_right(struct nilfs_btree *btree,
 
 	path[level + 1].bp_index++;
 	nilfs_btree_promote_key(btree, path, level + 1,
-				nilfs_btree_node_get_key(btree, right, 0));
+				nilfs_btree_node_get_key(right, 0));
 	path[level + 1].bp_index--;
 
 	if (move) {
 		brelse(path[level].bp_bh);
 		path[level].bp_bh = path[level].bp_sib_bh;
 		path[level].bp_sib_bh = NULL;
-		path[level].bp_index -=
-			nilfs_btree_node_get_nchildren(btree, node);
+		path[level].bp_index -= nilfs_btree_node_get_nchildren(node);
 		path[level + 1].bp_index++;
 	} else {
 		brelse(path[level].bp_sib_bh);
@@ -846,9 +797,9 @@ static void nilfs_btree_split(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	right = nilfs_btree_get_sib_node(btree, path, level);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	right = nilfs_btree_get_sib_node(path, level);
+	nchildren = nilfs_btree_node_get_nchildren(node);
 	move = 0;
 
 	n = (nchildren + 1) / 2;
@@ -867,16 +818,15 @@ static void nilfs_btree_split(struct nilfs_btree *btree,
 	unlock_buffer(path[level].bp_bh);
 	unlock_buffer(path[level].bp_sib_bh);
 
-	newkey = nilfs_btree_node_get_key(btree, right, 0);
+	newkey = nilfs_btree_node_get_key(right, 0);
 	newptr = path[level].bp_newreq.bpr_ptr;
 
 	if (move) {
-		path[level].bp_index -=
-			nilfs_btree_node_get_nchildren(btree, node);
+		path[level].bp_index -= nilfs_btree_node_get_nchildren(node);
 		nilfs_btree_node_insert(btree, right, *keyp, *ptrp,
 					path[level].bp_index);
 
-		*keyp = nilfs_btree_node_get_key(btree, right, 0);
+		*keyp = nilfs_btree_node_get_key(right, 0);
 		*ptrp = path[level].bp_newreq.bpr_ptr;
 
 		brelse(path[level].bp_bh);
@@ -885,7 +835,7 @@ static void nilfs_btree_split(struct nilfs_btree *btree,
 	} else {
 		nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
 
-		*keyp = nilfs_btree_node_get_key(btree, right, 0);
+		*keyp = nilfs_btree_node_get_key(right, 0);
 		*ptrp = path[level].bp_newreq.bpr_ptr;
 
 		brelse(path[level].bp_sib_bh);
@@ -905,12 +855,12 @@ static void nilfs_btree_grow(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_sib_bh);
 
 	root = nilfs_btree_get_root(btree);
-	child = nilfs_btree_get_sib_node(btree, path, level);
+	child = nilfs_btree_get_sib_node(path, level);
 
-	n = nilfs_btree_node_get_nchildren(btree, root);
+	n = nilfs_btree_node_get_nchildren(root);
 
 	nilfs_btree_node_move_right(btree, root, child, n);
-	nilfs_btree_node_set_level(btree, root, level + 1);
+	nilfs_btree_node_set_level(root, level + 1);
 
 	if (!buffer_dirty(path[level].bp_sib_bh))
 		nilfs_btnode_mark_dirty(path[level].bp_sib_bh);
@@ -922,7 +872,7 @@ static void nilfs_btree_grow(struct nilfs_btree *btree,
 
 	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
 
-	*keyp = nilfs_btree_node_get_key(btree, child, 0);
+	*keyp = nilfs_btree_node_get_key(child, 0);
 	*ptrp = path[level].bp_newreq.bpr_ptr;
 }
 
@@ -990,26 +940,29 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 	struct nilfs_btree_node *node, *parent, *sib;
 	__u64 sibptr;
 	int pindex, level, ret;
+	struct inode *dat = NULL;
 
 	stats->bs_nblocks = 0;
 	level = NILFS_BTREE_LEVEL_DATA;
 
 	/* allocate a new ptr for data block */
-	if (NILFS_BMAP_USE_VBN(&btree->bt_bmap))
+	if (NILFS_BMAP_USE_VBN(&btree->bt_bmap)) {
 		path[level].bp_newreq.bpr_ptr =
 			nilfs_btree_find_target_v(btree, path, key);
+		dat = nilfs_bmap_get_dat(&btree->bt_bmap);
+	}
 
 	ret = nilfs_bmap_prepare_alloc_ptr(&btree->bt_bmap,
-					   &path[level].bp_newreq);
+					   &path[level].bp_newreq, dat);
 	if (ret < 0)
 		goto err_out_data;
 
 	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
 	     level < nilfs_btree_height(btree) - 1;
 	     level++) {
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
-		if (nilfs_btree_node_get_nchildren(btree, node) <
-		    nilfs_btree_node_nchildren_max(btree, node)) {
+		node = nilfs_btree_get_nonroot_node(path, level);
+		if (nilfs_btree_node_get_nchildren(node) <
+		    nilfs_btree_node_nchildren_max(node, btree)) {
 			path[level].bp_op = nilfs_btree_do_insert;
 			stats->bs_nblocks++;
 			goto out;
@@ -1026,8 +979,8 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 			if (ret < 0)
 				goto err_out_child_node;
 			sib = (struct nilfs_btree_node *)bh->b_data;
-			if (nilfs_btree_node_get_nchildren(btree, sib) <
-			    nilfs_btree_node_nchildren_max(btree, sib)) {
+			if (nilfs_btree_node_get_nchildren(sib) <
+			    nilfs_btree_node_nchildren_max(sib, btree)) {
 				path[level].bp_sib_bh = bh;
 				path[level].bp_op = nilfs_btree_carry_left;
 				stats->bs_nblocks++;
@@ -1038,15 +991,15 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 
 		/* right sibling */
 		if (pindex <
-		    nilfs_btree_node_get_nchildren(btree, parent) - 1) {
+		    nilfs_btree_node_get_nchildren(parent) - 1) {
 			sibptr = nilfs_btree_node_get_ptr(btree, parent,
 							  pindex + 1);
 			ret = nilfs_btree_get_block(btree, sibptr, &bh);
 			if (ret < 0)
 				goto err_out_child_node;
 			sib = (struct nilfs_btree_node *)bh->b_data;
-			if (nilfs_btree_node_get_nchildren(btree, sib) <
-			    nilfs_btree_node_nchildren_max(btree, sib)) {
+			if (nilfs_btree_node_get_nchildren(sib) <
+			    nilfs_btree_node_nchildren_max(sib, btree)) {
 				path[level].bp_sib_bh = bh;
 				path[level].bp_op = nilfs_btree_carry_right;
 				stats->bs_nblocks++;
@@ -1059,7 +1012,7 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 		path[level].bp_newreq.bpr_ptr =
 			path[level - 1].bp_newreq.bpr_ptr + 1;
 		ret = nilfs_bmap_prepare_alloc_ptr(&btree->bt_bmap,
-						   &path[level].bp_newreq);
+						   &path[level].bp_newreq, dat);
 		if (ret < 0)
 			goto err_out_child_node;
 		ret = nilfs_btree_get_new_block(btree,
@@ -1081,8 +1034,8 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 
 	/* root */
 	node = nilfs_btree_get_root(btree);
-	if (nilfs_btree_node_get_nchildren(btree, node) <
-	    nilfs_btree_node_nchildren_max(btree, node)) {
+	if (nilfs_btree_node_get_nchildren(node) <
+	    nilfs_btree_node_nchildren_max(node, btree)) {
 		path[level].bp_op = nilfs_btree_do_insert;
 		stats->bs_nblocks++;
 		goto out;
@@ -1091,7 +1044,7 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 	/* grow */
 	path[level].bp_newreq.bpr_ptr = path[level - 1].bp_newreq.bpr_ptr + 1;
 	ret = nilfs_bmap_prepare_alloc_ptr(&btree->bt_bmap,
-					   &path[level].bp_newreq);
+					   &path[level].bp_newreq, dat);
 	if (ret < 0)
 		goto err_out_child_node;
 	ret = nilfs_btree_get_new_block(btree, path[level].bp_newreq.bpr_ptr,
@@ -1119,16 +1072,18 @@ static int nilfs_btree_prepare_insert(struct nilfs_btree *btree,
 
 	/* error */
  err_out_curr_node:
-	nilfs_bmap_abort_alloc_ptr(&btree->bt_bmap, &path[level].bp_newreq);
+	nilfs_bmap_abort_alloc_ptr(&btree->bt_bmap, &path[level].bp_newreq,
+				   dat);
  err_out_child_node:
 	for (level--; level > NILFS_BTREE_LEVEL_DATA; level--) {
 		nilfs_btnode_delete(path[level].bp_sib_bh);
 		nilfs_bmap_abort_alloc_ptr(&btree->bt_bmap,
-					   &path[level].bp_newreq);
+					   &path[level].bp_newreq, dat);
 
 	}
 
-	nilfs_bmap_abort_alloc_ptr(&btree->bt_bmap, &path[level].bp_newreq);
+	nilfs_bmap_abort_alloc_ptr(&btree->bt_bmap, &path[level].bp_newreq,
+				   dat);
  err_out_data:
 	*levelp = level;
 	stats->bs_nblocks = 0;
@@ -1139,16 +1094,19 @@ static void nilfs_btree_commit_insert(struct nilfs_btree *btree,
 				      struct nilfs_btree_path *path,
 				      int maxlevel, __u64 key, __u64 ptr)
 {
+	struct inode *dat = NULL;
 	int level;
 
 	set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
 	ptr = path[NILFS_BTREE_LEVEL_DATA].bp_newreq.bpr_ptr;
-	if (NILFS_BMAP_USE_VBN(&btree->bt_bmap))
+	if (NILFS_BMAP_USE_VBN(&btree->bt_bmap)) {
 		nilfs_btree_set_target_v(btree, key, ptr);
+		dat = nilfs_bmap_get_dat(&btree->bt_bmap);
+	}
 
 	for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
 		nilfs_bmap_commit_alloc_ptr(&btree->bt_bmap,
-					    &path[level - 1].bp_newreq);
+					    &path[level - 1].bp_newreq, dat);
 		path[level].bp_op(btree, path, level, &key, &ptr);
 	}
 
@@ -1164,10 +1122,10 @@ static int nilfs_btree_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
 	int level, ret;
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
 				    NILFS_BTREE_LEVEL_NODE_MIN);
@@ -1184,8 +1142,8 @@ static int nilfs_btree_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
 	nilfs_bmap_add_blocks(bmap, stats.bs_nblocks);
 
  out:
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 	return ret;
 }
 
@@ -1197,7 +1155,7 @@ static void nilfs_btree_do_delete(struct nilfs_btree *btree,
 
 	if (level < nilfs_btree_height(btree) - 1) {
 		lock_buffer(path[level].bp_bh);
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		node = nilfs_btree_get_nonroot_node(path, level);
 		nilfs_btree_node_delete(btree, node, keyp, ptrp,
 					path[level].bp_index);
 		if (!buffer_dirty(path[level].bp_bh))
@@ -1205,7 +1163,7 @@ static void nilfs_btree_do_delete(struct nilfs_btree *btree,
 		unlock_buffer(path[level].bp_bh);
 		if (path[level].bp_index == 0)
 			nilfs_btree_promote_key(btree, path, level + 1,
-				nilfs_btree_node_get_key(btree, node, 0));
+				nilfs_btree_node_get_key(node, 0));
 	} else {
 		node = nilfs_btree_get_root(btree);
 		nilfs_btree_node_delete(btree, node, keyp, ptrp,
@@ -1225,10 +1183,10 @@ static void nilfs_btree_borrow_left(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	left = nilfs_btree_get_sib_node(btree, path, level);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
-	lnchildren = nilfs_btree_node_get_nchildren(btree, left);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	left = nilfs_btree_get_sib_node(path, level);
+	nchildren = nilfs_btree_node_get_nchildren(node);
+	lnchildren = nilfs_btree_node_get_nchildren(left);
 
 	n = (nchildren + lnchildren) / 2 - nchildren;
 
@@ -1243,7 +1201,7 @@ static void nilfs_btree_borrow_left(struct nilfs_btree *btree,
 	unlock_buffer(path[level].bp_sib_bh);
 
 	nilfs_btree_promote_key(btree, path, level + 1,
-				nilfs_btree_node_get_key(btree, node, 0));
+				nilfs_btree_node_get_key(node, 0));
 
 	brelse(path[level].bp_sib_bh);
 	path[level].bp_sib_bh = NULL;
@@ -1262,10 +1220,10 @@ static void nilfs_btree_borrow_right(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	right = nilfs_btree_get_sib_node(btree, path, level);
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
-	rnchildren = nilfs_btree_node_get_nchildren(btree, right);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	right = nilfs_btree_get_sib_node(path, level);
+	nchildren = nilfs_btree_node_get_nchildren(node);
+	rnchildren = nilfs_btree_node_get_nchildren(right);
 
 	n = (nchildren + rnchildren) / 2 - nchildren;
 
@@ -1281,7 +1239,7 @@ static void nilfs_btree_borrow_right(struct nilfs_btree *btree,
 
 	path[level + 1].bp_index++;
 	nilfs_btree_promote_key(btree, path, level + 1,
-				nilfs_btree_node_get_key(btree, right, 0));
+				nilfs_btree_node_get_key(right, 0));
 	path[level + 1].bp_index--;
 
 	brelse(path[level].bp_sib_bh);
@@ -1300,10 +1258,10 @@ static void nilfs_btree_concat_left(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	left = nilfs_btree_get_sib_node(btree, path, level);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	left = nilfs_btree_get_sib_node(path, level);
 
-	n = nilfs_btree_node_get_nchildren(btree, node);
+	n = nilfs_btree_node_get_nchildren(node);
 
 	nilfs_btree_node_move_left(btree, left, node, n);
 
@@ -1316,7 +1274,7 @@ static void nilfs_btree_concat_left(struct nilfs_btree *btree,
 	nilfs_btnode_delete(path[level].bp_bh);
 	path[level].bp_bh = path[level].bp_sib_bh;
 	path[level].bp_sib_bh = NULL;
-	path[level].bp_index += nilfs_btree_node_get_nchildren(btree, left);
+	path[level].bp_index += nilfs_btree_node_get_nchildren(left);
 }
 
 static void nilfs_btree_concat_right(struct nilfs_btree *btree,
@@ -1331,10 +1289,10 @@ static void nilfs_btree_concat_right(struct nilfs_btree *btree,
 	lock_buffer(path[level].bp_bh);
 	lock_buffer(path[level].bp_sib_bh);
 
-	node = nilfs_btree_get_nonroot_node(btree, path, level);
-	right = nilfs_btree_get_sib_node(btree, path, level);
+	node = nilfs_btree_get_nonroot_node(path, level);
+	right = nilfs_btree_get_sib_node(path, level);
 
-	n = nilfs_btree_node_get_nchildren(btree, right);
+	n = nilfs_btree_node_get_nchildren(right);
 
 	nilfs_btree_node_move_left(btree, node, right, n);
 
@@ -1360,11 +1318,11 @@ static void nilfs_btree_shrink(struct nilfs_btree *btree,
 
 	lock_buffer(path[level].bp_bh);
 	root = nilfs_btree_get_root(btree);
-	child = nilfs_btree_get_nonroot_node(btree, path, level);
+	child = nilfs_btree_get_nonroot_node(path, level);
 
 	nilfs_btree_node_delete(btree, root, NULL, NULL, 0);
-	nilfs_btree_node_set_level(btree, root, level);
-	n = nilfs_btree_node_get_nchildren(btree, child);
+	nilfs_btree_node_set_level(root, level);
+	n = nilfs_btree_node_get_nchildren(child);
 	nilfs_btree_node_move_left(btree, root, child, n);
 	unlock_buffer(path[level].bp_bh);
 
@@ -1376,7 +1334,8 @@ static void nilfs_btree_shrink(struct nilfs_btree *btree,
 static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 				      struct nilfs_btree_path *path,
 				      int *levelp,
-				      struct nilfs_bmap_stats *stats)
+				      struct nilfs_bmap_stats *stats,
+				      struct inode *dat)
 {
 	struct buffer_head *bh;
 	struct nilfs_btree_node *node, *parent, *sib;
@@ -1388,17 +1347,17 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
 	     level < nilfs_btree_height(btree) - 1;
 	     level++) {
-		node = nilfs_btree_get_nonroot_node(btree, path, level);
+		node = nilfs_btree_get_nonroot_node(path, level);
 		path[level].bp_oldreq.bpr_ptr =
 			nilfs_btree_node_get_ptr(btree, node,
 						 path[level].bp_index);
 		ret = nilfs_bmap_prepare_end_ptr(&btree->bt_bmap,
-						 &path[level].bp_oldreq);
+						 &path[level].bp_oldreq, dat);
 		if (ret < 0)
 			goto err_out_child_node;
 
-		if (nilfs_btree_node_get_nchildren(btree, node) >
-		    nilfs_btree_node_nchildren_min(btree, node)) {
+		if (nilfs_btree_node_get_nchildren(node) >
+		    nilfs_btree_node_nchildren_min(node, btree)) {
 			path[level].bp_op = nilfs_btree_do_delete;
 			stats->bs_nblocks++;
 			goto out;
@@ -1415,8 +1374,8 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 			if (ret < 0)
 				goto err_out_curr_node;
 			sib = (struct nilfs_btree_node *)bh->b_data;
-			if (nilfs_btree_node_get_nchildren(btree, sib) >
-			    nilfs_btree_node_nchildren_min(btree, sib)) {
+			if (nilfs_btree_node_get_nchildren(sib) >
+			    nilfs_btree_node_nchildren_min(sib, btree)) {
 				path[level].bp_sib_bh = bh;
 				path[level].bp_op = nilfs_btree_borrow_left;
 				stats->bs_nblocks++;
@@ -1428,7 +1387,7 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 				/* continue; */
 			}
 		} else if (pindex <
-			   nilfs_btree_node_get_nchildren(btree, parent) - 1) {
+			   nilfs_btree_node_get_nchildren(parent) - 1) {
 			/* right sibling */
 			sibptr = nilfs_btree_node_get_ptr(btree, parent,
 							  pindex + 1);
@@ -1436,8 +1395,8 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 			if (ret < 0)
 				goto err_out_curr_node;
 			sib = (struct nilfs_btree_node *)bh->b_data;
-			if (nilfs_btree_node_get_nchildren(btree, sib) >
-			    nilfs_btree_node_nchildren_min(btree, sib)) {
+			if (nilfs_btree_node_get_nchildren(sib) >
+			    nilfs_btree_node_nchildren_min(sib, btree)) {
 				path[level].bp_sib_bh = bh;
 				path[level].bp_op = nilfs_btree_borrow_right;
 				stats->bs_nblocks++;
@@ -1452,7 +1411,7 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 			/* no siblings */
 			/* the only child of the root node */
 			WARN_ON(level != nilfs_btree_height(btree) - 2);
-			if (nilfs_btree_node_get_nchildren(btree, node) - 1 <=
+			if (nilfs_btree_node_get_nchildren(node) - 1 <=
 			    NILFS_BTREE_ROOT_NCHILDREN_MAX) {
 				path[level].bp_op = nilfs_btree_shrink;
 				stats->bs_nblocks += 2;
@@ -1471,7 +1430,7 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 		nilfs_btree_node_get_ptr(btree, node, path[level].bp_index);
 
 	ret = nilfs_bmap_prepare_end_ptr(&btree->bt_bmap,
-					 &path[level].bp_oldreq);
+					 &path[level].bp_oldreq, dat);
 	if (ret < 0)
 		goto err_out_child_node;
 
@@ -1486,12 +1445,12 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 
 	/* error */
  err_out_curr_node:
-	nilfs_bmap_abort_end_ptr(&btree->bt_bmap, &path[level].bp_oldreq);
+	nilfs_bmap_abort_end_ptr(&btree->bt_bmap, &path[level].bp_oldreq, dat);
  err_out_child_node:
 	for (level--; level >= NILFS_BTREE_LEVEL_NODE_MIN; level--) {
 		brelse(path[level].bp_sib_bh);
 		nilfs_bmap_abort_end_ptr(&btree->bt_bmap,
-					 &path[level].bp_oldreq);
+					 &path[level].bp_oldreq, dat);
 	}
 	*levelp = level;
 	stats->bs_nblocks = 0;
@@ -1500,13 +1459,13 @@ static int nilfs_btree_prepare_delete(struct nilfs_btree *btree,
 
 static void nilfs_btree_commit_delete(struct nilfs_btree *btree,
 				      struct nilfs_btree_path *path,
-				      int maxlevel)
+				      int maxlevel, struct inode *dat)
 {
 	int level;
 
 	for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
 		nilfs_bmap_commit_end_ptr(&btree->bt_bmap,
-					  &path[level].bp_oldreq);
+					  &path[level].bp_oldreq, dat);
 		path[level].bp_op(btree, path, level, NULL, NULL);
 	}
 
@@ -1520,27 +1479,32 @@ static int nilfs_btree_delete(struct nilfs_bmap *bmap, __u64 key)
 	struct nilfs_btree *btree;
 	struct nilfs_btree_path *path;
 	struct nilfs_bmap_stats stats;
+	struct inode *dat;
 	int level, ret;
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
 				    NILFS_BTREE_LEVEL_NODE_MIN);
 	if (ret < 0)
 		goto out;
 
-	ret = nilfs_btree_prepare_delete(btree, path, &level, &stats);
+
+	dat = NILFS_BMAP_USE_VBN(&btree->bt_bmap) ?
+		nilfs_bmap_get_dat(&btree->bt_bmap) : NULL;
+
+	ret = nilfs_btree_prepare_delete(btree, path, &level, &stats, dat);
 	if (ret < 0)
 		goto out;
-	nilfs_btree_commit_delete(btree, path, level);
+	nilfs_btree_commit_delete(btree, path, level, dat);
 	nilfs_bmap_sub_blocks(bmap, stats.bs_nblocks);
 
 out:
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 	return ret;
 }
 
@@ -1551,15 +1515,15 @@ static int nilfs_btree_last_key(const struct nilfs_bmap *bmap, __u64 *keyp)
 	int ret;
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup_last(btree, path, keyp, NULL);
 
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 
 	return ret;
 }
@@ -1581,7 +1545,7 @@ static int nilfs_btree_check_delete(struct nilfs_bmap *bmap, __u64 key)
 		node = root;
 		break;
 	case 3:
-		nchildren = nilfs_btree_node_get_nchildren(btree, root);
+		nchildren = nilfs_btree_node_get_nchildren(root);
 		if (nchildren > 1)
 			return 0;
 		ptr = nilfs_btree_node_get_ptr(btree, root, nchildren - 1);
@@ -1594,10 +1558,10 @@ static int nilfs_btree_check_delete(struct nilfs_bmap *bmap, __u64 key)
 		return 0;
 	}
 
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
-	maxkey = nilfs_btree_node_get_key(btree, node, nchildren - 1);
+	nchildren = nilfs_btree_node_get_nchildren(node);
+	maxkey = nilfs_btree_node_get_key(node, nchildren - 1);
 	nextmaxkey = (nchildren > 1) ?
-		nilfs_btree_node_get_key(btree, node, nchildren - 2) : 0;
+		nilfs_btree_node_get_key(node, nchildren - 2) : 0;
 	if (bh != NULL)
 		brelse(bh);
 
@@ -1623,7 +1587,7 @@ static int nilfs_btree_gather_data(struct nilfs_bmap *bmap,
 		node = root;
 		break;
 	case 3:
-		nchildren = nilfs_btree_node_get_nchildren(btree, root);
+		nchildren = nilfs_btree_node_get_nchildren(root);
 		WARN_ON(nchildren > 1);
 		ptr = nilfs_btree_node_get_ptr(btree, root, nchildren - 1);
 		ret = nilfs_btree_get_block(btree, ptr, &bh);
@@ -1636,11 +1600,11 @@ static int nilfs_btree_gather_data(struct nilfs_bmap *bmap,
 		return -EINVAL;
 	}
 
-	nchildren = nilfs_btree_node_get_nchildren(btree, node);
+	nchildren = nilfs_btree_node_get_nchildren(node);
 	if (nchildren < nitems)
 		nitems = nchildren;
-	dkeys = nilfs_btree_node_dkeys(btree, node);
-	dptrs = nilfs_btree_node_dptrs(btree, node);
+	dkeys = nilfs_btree_node_dkeys(node);
+	dptrs = nilfs_btree_node_dptrs(node, btree);
 	for (i = 0; i < nitems; i++) {
 		keys[i] = nilfs_bmap_dkey_to_key(dkeys[i]);
 		ptrs[i] = nilfs_bmap_dptr_to_ptr(dptrs[i]);
@@ -1660,18 +1624,20 @@ nilfs_btree_prepare_convert_and_insert(struct nilfs_bmap *bmap, __u64 key,
 				       struct nilfs_bmap_stats *stats)
 {
 	struct buffer_head *bh;
-	struct nilfs_btree *btree;
+	struct nilfs_btree *btree = (struct nilfs_btree *)bmap;
+	struct inode *dat = NULL;
 	int ret;
 
-	btree = (struct nilfs_btree *)bmap;
 	stats->bs_nblocks = 0;
 
 	/* for data */
 	/* cannot find near ptr */
-	if (NILFS_BMAP_USE_VBN(bmap))
+	if (NILFS_BMAP_USE_VBN(bmap)) {
 		dreq->bpr_ptr = nilfs_btree_find_target_v(btree, NULL, key);
+		dat = nilfs_bmap_get_dat(bmap);
+	}
 
-	ret = nilfs_bmap_prepare_alloc_ptr(bmap, dreq);
+	ret = nilfs_bmap_prepare_alloc_ptr(bmap, dreq, dat);
 	if (ret < 0)
 		return ret;
 
@@ -1679,7 +1645,7 @@ nilfs_btree_prepare_convert_and_insert(struct nilfs_bmap *bmap, __u64 key,
 	stats->bs_nblocks++;
 	if (nreq != NULL) {
 		nreq->bpr_ptr = dreq->bpr_ptr + 1;
-		ret = nilfs_bmap_prepare_alloc_ptr(bmap, nreq);
+		ret = nilfs_bmap_prepare_alloc_ptr(bmap, nreq, dat);
 		if (ret < 0)
 			goto err_out_dreq;
 
@@ -1696,9 +1662,9 @@ nilfs_btree_prepare_convert_and_insert(struct nilfs_bmap *bmap, __u64 key,
 
 	/* error */
  err_out_nreq:
-	nilfs_bmap_abort_alloc_ptr(bmap, nreq);
+	nilfs_bmap_abort_alloc_ptr(bmap, nreq, dat);
  err_out_dreq:
-	nilfs_bmap_abort_alloc_ptr(bmap, dreq);
+	nilfs_bmap_abort_alloc_ptr(bmap, dreq, dat);
 	stats->bs_nblocks = 0;
 	return ret;
 
@@ -1713,8 +1679,9 @@ nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *bmap,
 				      union nilfs_bmap_ptr_req *nreq,
 				      struct buffer_head *bh)
 {
-	struct nilfs_btree *btree;
+	struct nilfs_btree *btree = (struct nilfs_btree *)bmap;
 	struct nilfs_btree_node *node;
+	struct inode *dat;
 	__u64 tmpptr;
 
 	/* free resources */
@@ -1725,11 +1692,11 @@ nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *bmap,
 	set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
 
 	/* convert and insert */
-	btree = (struct nilfs_btree *)bmap;
+	dat = NILFS_BMAP_USE_VBN(bmap) ? nilfs_bmap_get_dat(bmap) : NULL;
 	nilfs_btree_init(bmap);
 	if (nreq != NULL) {
-		nilfs_bmap_commit_alloc_ptr(bmap, dreq);
-		nilfs_bmap_commit_alloc_ptr(bmap, nreq);
+		nilfs_bmap_commit_alloc_ptr(bmap, dreq, dat);
+		nilfs_bmap_commit_alloc_ptr(bmap, nreq, dat);
 
 		/* create child node at level 1 */
 		lock_buffer(bh);
@@ -1751,7 +1718,7 @@ nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *bmap,
 		nilfs_btree_node_init(btree, node, NILFS_BTREE_NODE_ROOT,
 				      2, 1, &keys[0], &tmpptr);
 	} else {
-		nilfs_bmap_commit_alloc_ptr(bmap, dreq);
+		nilfs_bmap_commit_alloc_ptr(bmap, dreq, dat);
 
 		/* create root node at level 1 */
 		node = nilfs_btree_get_root(btree);
@@ -1822,7 +1789,7 @@ static int nilfs_btree_propagate_p(struct nilfs_btree *btree,
 
 static int nilfs_btree_prepare_update_v(struct nilfs_btree *btree,
 					struct nilfs_btree_path *path,
-					int level)
+					int level, struct inode *dat)
 {
 	struct nilfs_btree_node *parent;
 	int ret;
@@ -1832,9 +1799,8 @@ static int nilfs_btree_prepare_update_v(struct nilfs_btree *btree,
 		nilfs_btree_node_get_ptr(btree, parent,
 					 path[level + 1].bp_index);
 	path[level].bp_newreq.bpr_ptr = path[level].bp_oldreq.bpr_ptr + 1;
-	ret = nilfs_bmap_prepare_update_v(&btree->bt_bmap,
-					  &path[level].bp_oldreq,
-					  &path[level].bp_newreq);
+	ret = nilfs_dat_prepare_update(dat, &path[level].bp_oldreq.bpr_req,
+				       &path[level].bp_newreq.bpr_req);
 	if (ret < 0)
 		return ret;
 
@@ -1846,9 +1812,9 @@ static int nilfs_btree_prepare_update_v(struct nilfs_btree *btree,
 			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
 			&path[level].bp_ctxt);
 		if (ret < 0) {
-			nilfs_bmap_abort_update_v(&btree->bt_bmap,
-						  &path[level].bp_oldreq,
-						  &path[level].bp_newreq);
+			nilfs_dat_abort_update(dat,
+					       &path[level].bp_oldreq.bpr_req,
+					       &path[level].bp_newreq.bpr_req);
 			return ret;
 		}
 	}
@@ -1858,13 +1824,13 @@ static int nilfs_btree_prepare_update_v(struct nilfs_btree *btree,
 
 static void nilfs_btree_commit_update_v(struct nilfs_btree *btree,
 					struct nilfs_btree_path *path,
-					int level)
+					int level, struct inode *dat)
 {
 	struct nilfs_btree_node *parent;
 
-	nilfs_bmap_commit_update_v(&btree->bt_bmap,
-				   &path[level].bp_oldreq,
-				   &path[level].bp_newreq);
+	nilfs_dat_commit_update(dat, &path[level].bp_oldreq.bpr_req,
+				&path[level].bp_newreq.bpr_req,
+				btree->bt_bmap.b_ptr_type == NILFS_BMAP_PTR_VS);
 
 	if (buffer_nilfs_node(path[level].bp_bh)) {
 		nilfs_btnode_commit_change_key(
@@ -1881,11 +1847,10 @@ static void nilfs_btree_commit_update_v(struct nilfs_btree *btree,
 
 static void nilfs_btree_abort_update_v(struct nilfs_btree *btree,
 				       struct nilfs_btree_path *path,
-				       int level)
+				       int level, struct inode *dat)
 {
-	nilfs_bmap_abort_update_v(&btree->bt_bmap,
-				  &path[level].bp_oldreq,
-				  &path[level].bp_newreq);
+	nilfs_dat_abort_update(dat, &path[level].bp_oldreq.bpr_req,
+			       &path[level].bp_newreq.bpr_req);
 	if (buffer_nilfs_node(path[level].bp_bh))
 		nilfs_btnode_abort_change_key(
 			&NILFS_BMAP_I(&btree->bt_bmap)->i_btnode_cache,
@@ -1894,14 +1859,14 @@ static void nilfs_btree_abort_update_v(struct nilfs_btree *btree,
 
 static int nilfs_btree_prepare_propagate_v(struct nilfs_btree *btree,
 					   struct nilfs_btree_path *path,
-					   int minlevel,
-					   int *maxlevelp)
+					   int minlevel, int *maxlevelp,
+					   struct inode *dat)
 {
 	int level, ret;
 
 	level = minlevel;
 	if (!buffer_nilfs_volatile(path[level].bp_bh)) {
-		ret = nilfs_btree_prepare_update_v(btree, path, level);
+		ret = nilfs_btree_prepare_update_v(btree, path, level, dat);
 		if (ret < 0)
 			return ret;
 	}
@@ -1909,7 +1874,7 @@ static int nilfs_btree_prepare_propagate_v(struct nilfs_btree *btree,
 	       !buffer_dirty(path[level].bp_bh)) {
 
 		WARN_ON(buffer_nilfs_volatile(path[level].bp_bh));
-		ret = nilfs_btree_prepare_update_v(btree, path, level);
+		ret = nilfs_btree_prepare_update_v(btree, path, level, dat);
 		if (ret < 0)
 			goto out;
 	}
@@ -1921,39 +1886,40 @@ static int nilfs_btree_prepare_propagate_v(struct nilfs_btree *btree,
 	/* error */
  out:
 	while (--level > minlevel)
-		nilfs_btree_abort_update_v(btree, path, level);
+		nilfs_btree_abort_update_v(btree, path, level, dat);
 	if (!buffer_nilfs_volatile(path[level].bp_bh))
-		nilfs_btree_abort_update_v(btree, path, level);
+		nilfs_btree_abort_update_v(btree, path, level, dat);
 	return ret;
 }
 
 static void nilfs_btree_commit_propagate_v(struct nilfs_btree *btree,
 					   struct nilfs_btree_path *path,
-					   int minlevel,
-					   int maxlevel,
-					   struct buffer_head *bh)
+					   int minlevel, int maxlevel,
+					   struct buffer_head *bh,
+					   struct inode *dat)
 {
 	int level;
 
 	if (!buffer_nilfs_volatile(path[minlevel].bp_bh))
-		nilfs_btree_commit_update_v(btree, path, minlevel);
+		nilfs_btree_commit_update_v(btree, path, minlevel, dat);
 
 	for (level = minlevel + 1; level <= maxlevel; level++)
-		nilfs_btree_commit_update_v(btree, path, level);
+		nilfs_btree_commit_update_v(btree, path, level, dat);
 }
 
 static int nilfs_btree_propagate_v(struct nilfs_btree *btree,
 				   struct nilfs_btree_path *path,
-				   int level,
-				   struct buffer_head *bh)
+				   int level, struct buffer_head *bh)
 {
 	int maxlevel, ret;
 	struct nilfs_btree_node *parent;
+	struct inode *dat = nilfs_bmap_get_dat(&btree->bt_bmap);
 	__u64 ptr;
 
 	get_bh(bh);
 	path[level].bp_bh = bh;
-	ret = nilfs_btree_prepare_propagate_v(btree, path, level, &maxlevel);
+	ret = nilfs_btree_prepare_propagate_v(btree, path, level, &maxlevel,
+					      dat);
 	if (ret < 0)
 		goto out;
 
@@ -1961,12 +1927,12 @@ static int nilfs_btree_propagate_v(struct nilfs_btree *btree,
 		parent = nilfs_btree_get_node(btree, path, level + 1);
 		ptr = nilfs_btree_node_get_ptr(btree, parent,
 					       path[level + 1].bp_index);
-		ret = nilfs_bmap_mark_dirty(&btree->bt_bmap, ptr);
+		ret = nilfs_dat_mark_dirty(dat, ptr);
 		if (ret < 0)
 			goto out;
 	}
 
-	nilfs_btree_commit_propagate_v(btree, path, level, maxlevel, bh);
+	nilfs_btree_commit_propagate_v(btree, path, level, maxlevel, bh, dat);
 
  out:
 	brelse(path[level].bp_bh);
@@ -1986,15 +1952,15 @@ static int nilfs_btree_propagate(const struct nilfs_bmap *bmap,
 	WARN_ON(!buffer_dirty(bh));
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 
 	if (buffer_nilfs_node(bh)) {
 		node = (struct nilfs_btree_node *)bh->b_data;
-		key = nilfs_btree_node_get_key(btree, node, 0);
-		level = nilfs_btree_node_get_level(btree, node);
+		key = nilfs_btree_node_get_key(node, 0);
+		level = nilfs_btree_node_get_level(node);
 	} else {
 		key = nilfs_bmap_data_get_key(bmap, bh);
 		level = NILFS_BTREE_LEVEL_DATA;
@@ -2013,8 +1979,8 @@ static int nilfs_btree_propagate(const struct nilfs_bmap *bmap,
 		nilfs_btree_propagate_p(btree, path, level, bh);
 
  out:
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 
 	return ret;
 }
@@ -2022,7 +1988,7 @@ static int nilfs_btree_propagate(const struct nilfs_bmap *bmap,
 static int nilfs_btree_propagate_gc(const struct nilfs_bmap *bmap,
 				    struct buffer_head *bh)
 {
-	return nilfs_bmap_mark_dirty(bmap, bh->b_blocknr);
+	return nilfs_dat_mark_dirty(nilfs_bmap_get_dat(bmap), bh->b_blocknr);
 }
 
 static void nilfs_btree_add_dirty_buffer(struct nilfs_btree *btree,
@@ -2037,12 +2003,12 @@ static void nilfs_btree_add_dirty_buffer(struct nilfs_btree *btree,
 
 	get_bh(bh);
 	node = (struct nilfs_btree_node *)bh->b_data;
-	key = nilfs_btree_node_get_key(btree, node, 0);
-	level = nilfs_btree_node_get_level(btree, node);
+	key = nilfs_btree_node_get_key(node, 0);
+	level = nilfs_btree_node_get_level(node);
 	list_for_each(head, &lists[level]) {
 		cbh = list_entry(head, struct buffer_head, b_assoc_buffers);
 		cnode = (struct nilfs_btree_node *)cbh->b_data;
-		ckey = nilfs_btree_node_get_key(btree, cnode, 0);
+		ckey = nilfs_btree_node_get_key(cnode, 0);
 		if (key < ckey)
 			break;
 	}
@@ -2120,8 +2086,7 @@ static int nilfs_btree_assign_p(struct nilfs_btree *btree,
 	nilfs_btree_node_set_ptr(btree, parent,
 				 path[level + 1].bp_index, blocknr);
 
-	key = nilfs_btree_node_get_key(btree, parent,
-				       path[level + 1].bp_index);
+	key = nilfs_btree_node_get_key(parent, path[level + 1].bp_index);
 	/* on-disk format */
 	binfo->bi_dat.bi_blkoff = nilfs_bmap_key_to_dkey(key);
 	binfo->bi_dat.bi_level = level;
@@ -2137,6 +2102,7 @@ static int nilfs_btree_assign_v(struct nilfs_btree *btree,
 				union nilfs_binfo *binfo)
 {
 	struct nilfs_btree_node *parent;
+	struct inode *dat = nilfs_bmap_get_dat(&btree->bt_bmap);
 	__u64 key;
 	__u64 ptr;
 	union nilfs_bmap_ptr_req req;
@@ -2146,12 +2112,12 @@ static int nilfs_btree_assign_v(struct nilfs_btree *btree,
 	ptr = nilfs_btree_node_get_ptr(btree, parent,
 				       path[level + 1].bp_index);
 	req.bpr_ptr = ptr;
-	ret = nilfs_bmap_start_v(&btree->bt_bmap, &req, blocknr);
-	if (unlikely(ret < 0))
+	ret = nilfs_dat_prepare_start(dat, &req.bpr_req);
+	if (ret < 0)
 		return ret;
+	nilfs_dat_commit_start(dat, &req.bpr_req, blocknr);
 
-	key = nilfs_btree_node_get_key(btree, parent,
-				       path[level + 1].bp_index);
+	key = nilfs_btree_node_get_key(parent, path[level + 1].bp_index);
 	/* on-disk format */
 	binfo->bi_v.bi_vblocknr = nilfs_bmap_ptr_to_dptr(ptr);
 	binfo->bi_v.bi_blkoff = nilfs_bmap_key_to_dkey(key);
@@ -2171,15 +2137,15 @@ static int nilfs_btree_assign(struct nilfs_bmap *bmap,
 	int level, ret;
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 
 	if (buffer_nilfs_node(*bh)) {
 		node = (struct nilfs_btree_node *)(*bh)->b_data;
-		key = nilfs_btree_node_get_key(btree, node, 0);
-		level = nilfs_btree_node_get_level(btree, node);
+		key = nilfs_btree_node_get_key(node, 0);
+		level = nilfs_btree_node_get_level(node);
 	} else {
 		key = nilfs_bmap_data_get_key(bmap, *bh);
 		level = NILFS_BTREE_LEVEL_DATA;
@@ -2196,8 +2162,8 @@ static int nilfs_btree_assign(struct nilfs_bmap *bmap,
 		nilfs_btree_assign_p(btree, path, level, bh, blocknr, binfo);
 
  out:
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 
 	return ret;
 }
@@ -2207,19 +2173,18 @@ static int nilfs_btree_assign_gc(struct nilfs_bmap *bmap,
 				 sector_t blocknr,
 				 union nilfs_binfo *binfo)
 {
-	struct nilfs_btree *btree;
 	struct nilfs_btree_node *node;
 	__u64 key;
 	int ret;
 
-	btree = (struct nilfs_btree *)bmap;
-	ret = nilfs_bmap_move_v(bmap, (*bh)->b_blocknr, blocknr);
+	ret = nilfs_dat_move(nilfs_bmap_get_dat(bmap), (*bh)->b_blocknr,
+			     blocknr);
 	if (ret < 0)
 		return ret;
 
 	if (buffer_nilfs_node(*bh)) {
 		node = (struct nilfs_btree_node *)(*bh)->b_data;
-		key = nilfs_btree_node_get_key(btree, node, 0);
+		key = nilfs_btree_node_get_key(node, 0);
 	} else
 		key = nilfs_bmap_data_get_key(bmap, *bh);
 
@@ -2239,10 +2204,10 @@ static int nilfs_btree_mark(struct nilfs_bmap *bmap, __u64 key, int level)
 	int ret;
 
 	btree = (struct nilfs_btree *)bmap;
-	path = nilfs_btree_alloc_path(btree);
+	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(btree, path);
+	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level + 1);
 	if (ret < 0) {
@@ -2262,8 +2227,8 @@ static int nilfs_btree_mark(struct nilfs_bmap *bmap, __u64 key, int level)
 		nilfs_bmap_set_dirty(&btree->bt_bmap);
 
  out:
-	nilfs_btree_clear_path(btree, path);
-	nilfs_btree_free_path(btree, path);
+	nilfs_btree_release_path(path);
+	nilfs_btree_free_path(path);
 	return ret;
 }
 
diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index aec942cf79e..1c6cfb59128 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -815,8 +815,10 @@ int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 	void *kaddr;
 	int ret;
 
-	if (cno == 0)
-		return -ENOENT; /* checkpoint number 0 is invalid */
+	/* CP number is invalid if it's zero or larger than the
+	largest	exist one.*/
+	if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
+		return -ENOENT;
 	down_read(&NILFS_MDT(cpfile)->mi_sem);
 
 	ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
@@ -824,7 +826,10 @@ int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 		goto out;
 	kaddr = kmap_atomic(bh->b_page, KM_USER0);
 	cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
-	ret = nilfs_checkpoint_snapshot(cp);
+	if (nilfs_checkpoint_invalid(cp))
+		ret = -ENOENT;
+	else
+		ret = nilfs_checkpoint_snapshot(cp);
 	kunmap_atomic(kaddr, KM_USER0);
 	brelse(bh);
 
diff --git a/fs/nilfs2/cpfile.h b/fs/nilfs2/cpfile.h
index 788a4595019..debea896e70 100644
--- a/fs/nilfs2/cpfile.h
+++ b/fs/nilfs2/cpfile.h
@@ -27,8 +27,6 @@
 #include <linux/buffer_head.h>
 #include <linux/nilfs2_fs.h>
 
-#define NILFS_CPFILE_GFP	NILFS_MDT_GFP
-
 
 int nilfs_cpfile_get_checkpoint(struct inode *, __u64, int,
 				struct nilfs_checkpoint **,
diff --git a/fs/nilfs2/dat.c b/fs/nilfs2/dat.c
index 8927ca27e6f..1ff8e15bd36 100644
--- a/fs/nilfs2/dat.c
+++ b/fs/nilfs2/dat.c
@@ -109,12 +109,6 @@ void nilfs_dat_commit_free(struct inode *dat, struct nilfs_palloc_req *req)
 	nilfs_palloc_commit_free_entry(dat, req);
 }
 
-void nilfs_dat_abort_free(struct inode *dat, struct nilfs_palloc_req *req)
-{
-	nilfs_dat_abort_entry(dat, req);
-	nilfs_palloc_abort_free_entry(dat, req);
-}
-
 int nilfs_dat_prepare_start(struct inode *dat, struct nilfs_palloc_req *req)
 {
 	int ret;
@@ -140,11 +134,6 @@ void nilfs_dat_commit_start(struct inode *dat, struct nilfs_palloc_req *req,
 	nilfs_dat_commit_entry(dat, req);
 }
 
-void nilfs_dat_abort_start(struct inode *dat, struct nilfs_palloc_req *req)
-{
-	nilfs_dat_abort_entry(dat, req);
-}
-
 int nilfs_dat_prepare_end(struct inode *dat, struct nilfs_palloc_req *req)
 {
 	struct nilfs_dat_entry *entry;
@@ -222,6 +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
diff --git a/fs/nilfs2/dat.h b/fs/nilfs2/dat.h
index d328b81eead..406070d3ff4 100644
--- a/fs/nilfs2/dat.h
+++ b/fs/nilfs2/dat.h
@@ -27,7 +27,6 @@
 #include <linux/buffer_head.h>
 #include <linux/fs.h>
 
-#define NILFS_DAT_GFP	NILFS_MDT_GFP
 
 struct nilfs_palloc_req;
 
@@ -39,10 +38,15 @@ void nilfs_dat_abort_alloc(struct inode *, struct nilfs_palloc_req *);
 int nilfs_dat_prepare_start(struct inode *, struct nilfs_palloc_req *);
 void nilfs_dat_commit_start(struct inode *, struct nilfs_palloc_req *,
 			    sector_t);
-void nilfs_dat_abort_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);
diff --git a/fs/nilfs2/direct.c b/fs/nilfs2/direct.c
index 342d9765df8..d369ac71827 100644
--- a/fs/nilfs2/direct.c
+++ b/fs/nilfs2/direct.c
@@ -125,106 +125,64 @@ static void nilfs_direct_set_target_v(struct nilfs_direct *direct,
 	direct->d_bmap.b_last_allocated_ptr = ptr;
 }
 
-static int nilfs_direct_prepare_insert(struct nilfs_direct *direct,
-				       __u64 key,
-				       union nilfs_bmap_ptr_req *req,
-				       struct nilfs_bmap_stats *stats)
-{
-	int ret;
-
-	if (NILFS_BMAP_USE_VBN(&direct->d_bmap))
-		req->bpr_ptr = nilfs_direct_find_target_v(direct, key);
-	ret = nilfs_bmap_prepare_alloc_ptr(&direct->d_bmap, req);
-	if (ret < 0)
-		return ret;
-
-	stats->bs_nblocks = 1;
-	return 0;
-}
-
-static void nilfs_direct_commit_insert(struct nilfs_direct *direct,
-				       union nilfs_bmap_ptr_req *req,
-				       __u64 key, __u64 ptr)
-{
-	struct buffer_head *bh;
-
-	/* ptr must be a pointer to a buffer head. */
-	bh = (struct buffer_head *)((unsigned long)ptr);
-	set_buffer_nilfs_volatile(bh);
-
-	nilfs_bmap_commit_alloc_ptr(&direct->d_bmap, req);
-	nilfs_direct_set_ptr(direct, key, req->bpr_ptr);
-
-	if (!nilfs_bmap_dirty(&direct->d_bmap))
-		nilfs_bmap_set_dirty(&direct->d_bmap);
-
-	if (NILFS_BMAP_USE_VBN(&direct->d_bmap))
-		nilfs_direct_set_target_v(direct, key, req->bpr_ptr);
-}
-
 static int nilfs_direct_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
 {
-	struct nilfs_direct *direct;
+	struct nilfs_direct *direct = (struct nilfs_direct *)bmap;
 	union nilfs_bmap_ptr_req req;
-	struct nilfs_bmap_stats stats;
+	struct inode *dat = NULL;
+	struct buffer_head *bh;
 	int ret;
 
-	direct = (struct nilfs_direct *)bmap;
 	if (key > NILFS_DIRECT_KEY_MAX)
 		return -ENOENT;
 	if (nilfs_direct_get_ptr(direct, key) != NILFS_BMAP_INVALID_PTR)
 		return -EEXIST;
 
-	ret = nilfs_direct_prepare_insert(direct, key, &req, &stats);
-	if (ret < 0)
-		return ret;
-	nilfs_direct_commit_insert(direct, &req, key, ptr);
-	nilfs_bmap_add_blocks(bmap, stats.bs_nblocks);
+	if (NILFS_BMAP_USE_VBN(bmap)) {
+		req.bpr_ptr = nilfs_direct_find_target_v(direct, key);
+		dat = nilfs_bmap_get_dat(bmap);
+	}
+	ret = nilfs_bmap_prepare_alloc_ptr(bmap, &req, dat);
+	if (!ret) {
+		/* ptr must be a pointer to a buffer head. */
+		bh = (struct buffer_head *)((unsigned long)ptr);
+		set_buffer_nilfs_volatile(bh);
 
-	return 0;
-}
+		nilfs_bmap_commit_alloc_ptr(bmap, &req, dat);
+		nilfs_direct_set_ptr(direct, key, req.bpr_ptr);
 
-static int nilfs_direct_prepare_delete(struct nilfs_direct *direct,
-				       union nilfs_bmap_ptr_req *req,
-				       __u64 key,
-				       struct nilfs_bmap_stats *stats)
-{
-	int ret;
+		if (!nilfs_bmap_dirty(bmap))
+			nilfs_bmap_set_dirty(bmap);
 
-	req->bpr_ptr = nilfs_direct_get_ptr(direct, key);
-	ret = nilfs_bmap_prepare_end_ptr(&direct->d_bmap, req);
-	if (!ret)
-		stats->bs_nblocks = 1;
-	return ret;
-}
+		if (NILFS_BMAP_USE_VBN(bmap))
+			nilfs_direct_set_target_v(direct, key, req.bpr_ptr);
 
-static void nilfs_direct_commit_delete(struct nilfs_direct *direct,
-				       union nilfs_bmap_ptr_req *req,
-				       __u64 key)
-{
-	nilfs_bmap_commit_end_ptr(&direct->d_bmap, req);
-	nilfs_direct_set_ptr(direct, key, NILFS_BMAP_INVALID_PTR);
+		nilfs_bmap_add_blocks(bmap, 1);
+	}
+	return ret;
 }
 
 static int nilfs_direct_delete(struct nilfs_bmap *bmap, __u64 key)
 {
-	struct nilfs_direct *direct;
+	struct nilfs_direct *direct = (struct nilfs_direct *)bmap;
 	union nilfs_bmap_ptr_req req;
-	struct nilfs_bmap_stats stats;
+	struct inode *dat;
 	int ret;
 
-	direct = (struct nilfs_direct *)bmap;
-	if ((key > NILFS_DIRECT_KEY_MAX) ||
+	if (key > NILFS_DIRECT_KEY_MAX ||
 	    nilfs_direct_get_ptr(direct, key) == NILFS_BMAP_INVALID_PTR)
 		return -ENOENT;
 
-	ret = nilfs_direct_prepare_delete(direct, &req, key, &stats);
-	if (ret < 0)
-		return ret;
-	nilfs_direct_commit_delete(direct, &req, key);
-	nilfs_bmap_sub_blocks(bmap, stats.bs_nblocks);
+	dat = NILFS_BMAP_USE_VBN(bmap) ? nilfs_bmap_get_dat(bmap) : NULL;
+	req.bpr_ptr = nilfs_direct_get_ptr(direct, key);
 
-	return 0;
+	ret = nilfs_bmap_prepare_end_ptr(bmap, &req, dat);
+	if (!ret) {
+		nilfs_bmap_commit_end_ptr(bmap, &req, dat);
+		nilfs_direct_set_ptr(direct, key, NILFS_BMAP_INVALID_PTR);
+		nilfs_bmap_sub_blocks(bmap, 1);
+	}
+	return ret;
 }
 
 static int nilfs_direct_last_key(const struct nilfs_bmap *bmap, __u64 *keyp)
@@ -310,59 +268,56 @@ int nilfs_direct_delete_and_convert(struct nilfs_bmap *bmap,
 	return 0;
 }
 
-static int nilfs_direct_propagate_v(struct nilfs_direct *direct,
-				    struct buffer_head *bh)
+static int nilfs_direct_propagate(const struct nilfs_bmap *bmap,
+				  struct buffer_head *bh)
 {
-	union nilfs_bmap_ptr_req oldreq, newreq;
+	struct nilfs_direct *direct = (struct nilfs_direct *)bmap;
+	struct nilfs_palloc_req oldreq, newreq;
+	struct inode *dat;
 	__u64 key;
 	__u64 ptr;
 	int ret;
 
-	key = nilfs_bmap_data_get_key(&direct->d_bmap, bh);
+	if (!NILFS_BMAP_USE_VBN(bmap))
+		return 0;
+
+	dat = nilfs_bmap_get_dat(bmap);
+	key = nilfs_bmap_data_get_key(bmap, bh);
 	ptr = nilfs_direct_get_ptr(direct, key);
 	if (!buffer_nilfs_volatile(bh)) {
-		oldreq.bpr_ptr = ptr;
-		newreq.bpr_ptr = ptr;
-		ret = nilfs_bmap_prepare_update_v(&direct->d_bmap, &oldreq,
-						  &newreq);
+		oldreq.pr_entry_nr = ptr;
+		newreq.pr_entry_nr = ptr;
+		ret = nilfs_dat_prepare_update(dat, &oldreq, &newreq);
 		if (ret < 0)
 			return ret;
-		nilfs_bmap_commit_update_v(&direct->d_bmap, &oldreq, &newreq);
+		nilfs_dat_commit_update(dat, &oldreq, &newreq,
+					bmap->b_ptr_type == NILFS_BMAP_PTR_VS);
 		set_buffer_nilfs_volatile(bh);
-		nilfs_direct_set_ptr(direct, key, newreq.bpr_ptr);
+		nilfs_direct_set_ptr(direct, key, newreq.pr_entry_nr);
 	} else
-		ret = nilfs_bmap_mark_dirty(&direct->d_bmap, ptr);
+		ret = nilfs_dat_mark_dirty(dat, ptr);
 
 	return ret;
 }
 
-static int nilfs_direct_propagate(const struct nilfs_bmap *bmap,
-				  struct buffer_head *bh)
-{
-	struct nilfs_direct *direct = (struct nilfs_direct *)bmap;
-
-	return NILFS_BMAP_USE_VBN(bmap) ?
-		nilfs_direct_propagate_v(direct, bh) : 0;
-}
-
 static int nilfs_direct_assign_v(struct nilfs_direct *direct,
 				 __u64 key, __u64 ptr,
 				 struct buffer_head **bh,
 				 sector_t blocknr,
 				 union nilfs_binfo *binfo)
 {
+	struct inode *dat = nilfs_bmap_get_dat(&direct->d_bmap);
 	union nilfs_bmap_ptr_req req;
 	int ret;
 
 	req.bpr_ptr = ptr;
-	ret = nilfs_bmap_start_v(&direct->d_bmap, &req, blocknr);
-	if (unlikely(ret < 0))
-		return ret;
-
-	binfo->bi_v.bi_vblocknr = nilfs_bmap_ptr_to_dptr(ptr);
-	binfo->bi_v.bi_blkoff = nilfs_bmap_key_to_dkey(key);
-
-	return 0;
+	ret = nilfs_dat_prepare_start(dat, &req.bpr_req);
+	if (!ret) {
+		nilfs_dat_commit_start(dat, &req.bpr_req, blocknr);
+		binfo->bi_v.bi_vblocknr = nilfs_bmap_ptr_to_dptr(ptr);
+		binfo->bi_v.bi_blkoff = nilfs_bmap_key_to_dkey(key);
+	}
+	return ret;
 }
 
 static int nilfs_direct_assign_p(struct nilfs_direct *direct,
diff --git a/fs/nilfs2/ifile.h b/fs/nilfs2/ifile.h
index 5d30a35679b..ecc3ba76db4 100644
--- a/fs/nilfs2/ifile.h
+++ b/fs/nilfs2/ifile.h
@@ -31,7 +31,6 @@
 #include "mdt.h"
 #include "alloc.h"
 
-#define NILFS_IFILE_GFP  NILFS_MDT_GFP
 
 static inline struct nilfs_inode *
 nilfs_ifile_map_inode(struct inode *ifile, ino_t ino, struct buffer_head *ibh)
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index fe9d8f2a13f..807e584b163 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -430,7 +430,8 @@ static int __nilfs_read_inode(struct super_block *sb, unsigned long ino,
 
 	raw_inode = nilfs_ifile_map_inode(sbi->s_ifile, ino, bh);
 
-	if (nilfs_read_inode_common(inode, raw_inode))
+	err = nilfs_read_inode_common(inode, raw_inode);
+	if (err)
 		goto failed_unmap;
 
 	if (S_ISREG(inode->i_mode)) {
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 6ea5f872e2d..6572ea4bc4d 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -442,12 +442,6 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
 	const char *msg;
 	int ret;
 
-	ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], kbufs[0]);
-	if (ret < 0) {
-		msg = "cannot read source blocks";
-		goto failed;
-	}
-
 	ret = nilfs_ioctl_delete_checkpoints(nilfs, &argv[1], kbufs[1]);
 	if (ret < 0) {
 		/*
@@ -548,7 +542,25 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
 		}
 	}
 
-	ret = nilfs_clean_segments(inode->i_sb, argv, kbufs);
+	/*
+	 * nilfs_ioctl_move_blocks() will call nilfs_gc_iget(),
+	 * which will operates an inode list without blocking.
+	 * To protect the list from concurrent operations,
+	 * nilfs_ioctl_move_blocks should be atomic operation.
+	 */
+	if (test_and_set_bit(THE_NILFS_GC_RUNNING, &nilfs->ns_flags)) {
+		ret = -EBUSY;
+		goto out_free;
+	}
+
+	ret = nilfs_ioctl_move_blocks(nilfs, &argv[0], kbufs[0]);
+	if (ret < 0)
+		printk(KERN_ERR "NILFS: GC failed during preparation: "
+			"cannot read source blocks: err=%d\n", ret);
+	else
+		ret = nilfs_clean_segments(inode->i_sb, argv, kbufs);
+
+	clear_nilfs_gc_running(nilfs);
 
  out_free:
 	while (--n >= 0)
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index 2dfd47714ae..156bf6091a9 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -103,15 +103,12 @@ static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
 		goto failed_unlock;
 
 	err = -EEXIST;
-	if (buffer_uptodate(bh) || buffer_mapped(bh))
+	if (buffer_uptodate(bh))
 		goto failed_bh;
-#if 0
-	/* The uptodate flag is not protected by the page lock, but
-	   the mapped flag is.  Thus, we don't have to wait the buffer. */
+
 	wait_on_buffer(bh);
 	if (buffer_uptodate(bh))
 		goto failed_bh;
-#endif
 
 	bh->b_bdev = nilfs->ns_bdev;
 	err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
@@ -139,7 +136,7 @@ nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
 		       int mode, struct buffer_head **out_bh)
 {
 	struct buffer_head *bh;
-	unsigned long blknum = 0;
+	__u64 blknum = 0;
 	int ret = -ENOMEM;
 
 	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
@@ -162,17 +159,15 @@ nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
 		unlock_buffer(bh);
 		goto out;
 	}
-	if (!buffer_mapped(bh)) { /* unused buffer */
-		ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff,
-					&blknum);
-		if (unlikely(ret)) {
-			unlock_buffer(bh);
-			goto failed_bh;
-		}
-		bh->b_bdev = NILFS_MDT(inode)->mi_nilfs->ns_bdev;
-		bh->b_blocknr = blknum;
-		set_buffer_mapped(bh);
+
+	ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff, &blknum);
+	if (unlikely(ret)) {
+		unlock_buffer(bh);
+		goto failed_bh;
 	}
+	bh->b_bdev = NILFS_MDT(inode)->mi_nilfs->ns_bdev;
+	bh->b_blocknr = (sector_t)blknum;
+	set_buffer_mapped(bh);
 
 	bh->b_end_io = end_buffer_read_sync;
 	get_bh(bh);
@@ -402,6 +397,7 @@ nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
 	struct inode *inode = container_of(page->mapping,
 					   struct inode, i_data);
 	struct super_block *sb = inode->i_sb;
+	struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs;
 	struct nilfs_sb_info *writer = NULL;
 	int err = 0;
 
@@ -411,9 +407,10 @@ nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
 	if (page->mapping->assoc_mapping)
 		return 0; /* Do not request flush for shadow page cache */
 	if (!sb) {
-		writer = nilfs_get_writer(NILFS_MDT(inode)->mi_nilfs);
+		down_read(&nilfs->ns_writer_sem);
+		writer = nilfs->ns_writer;
 		if (!writer) {
-			nilfs_put_writer(NILFS_MDT(inode)->mi_nilfs);
+			up_read(&nilfs->ns_writer_sem);
 			return -EROFS;
 		}
 		sb = writer->s_super;
@@ -425,7 +422,7 @@ nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
 		nilfs_flush_segment(sb, inode->i_ino);
 
 	if (writer)
-		nilfs_put_writer(NILFS_MDT(inode)->mi_nilfs);
+		up_read(&nilfs->ns_writer_sem);
 	return err;
 }
 
@@ -516,9 +513,10 @@ nilfs_mdt_new_common(struct the_nilfs *nilfs, struct super_block *sb,
 }
 
 struct inode *nilfs_mdt_new(struct the_nilfs *nilfs, struct super_block *sb,
-			    ino_t ino, gfp_t gfp_mask)
+			    ino_t ino)
 {
-	struct inode *inode = nilfs_mdt_new_common(nilfs, sb, ino, gfp_mask);
+	struct inode *inode = nilfs_mdt_new_common(nilfs, sb, ino,
+						   NILFS_MDT_GFP);
 
 	if (!inode)
 		return NULL;
diff --git a/fs/nilfs2/mdt.h b/fs/nilfs2/mdt.h
index df683e0bca6..431599733c9 100644
--- a/fs/nilfs2/mdt.h
+++ b/fs/nilfs2/mdt.h
@@ -74,8 +74,7 @@ int nilfs_mdt_forget_block(struct inode *, unsigned long);
 int nilfs_mdt_mark_block_dirty(struct inode *, unsigned long);
 int nilfs_mdt_fetch_dirty(struct inode *);
 
-struct inode *nilfs_mdt_new(struct the_nilfs *, struct super_block *, ino_t,
-			    gfp_t);
+struct inode *nilfs_mdt_new(struct the_nilfs *, struct super_block *, ino_t);
 struct inode *nilfs_mdt_new_common(struct the_nilfs *, struct super_block *,
 				   ino_t, gfp_t);
 void nilfs_mdt_destroy(struct inode *);
diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c
index d80cc71be74..6dc83591d11 100644
--- a/fs/nilfs2/recovery.c
+++ b/fs/nilfs2/recovery.c
@@ -552,7 +552,8 @@ static int recover_dsync_blocks(struct nilfs_sb_info *sbi,
 		printk(KERN_WARNING
 		       "NILFS warning: error recovering data block "
 		       "(err=%d, ino=%lu, block-offset=%llu)\n",
-		       err, rb->ino, (unsigned long long)rb->blkoff);
+		       err, (unsigned long)rb->ino,
+		       (unsigned long long)rb->blkoff);
 		if (!err2)
 			err2 = err;
  next:
diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
index 9e3fe17bb96..e6d9e37fa24 100644
--- a/fs/nilfs2/segbuf.c
+++ b/fs/nilfs2/segbuf.c
@@ -316,10 +316,10 @@ static struct bio *nilfs_alloc_seg_bio(struct super_block *sb, sector_t start,
 {
 	struct bio *bio;
 
-	bio = bio_alloc(GFP_NOWAIT, nr_vecs);
+	bio = bio_alloc(GFP_NOIO, nr_vecs);
 	if (bio == NULL) {
 		while (!bio && (nr_vecs >>= 1))
-			bio = bio_alloc(GFP_NOWAIT, nr_vecs);
+			bio = bio_alloc(GFP_NOIO, nr_vecs);
 	}
 	if (likely(bio)) {
 		bio->bi_bdev = sb->s_bdev;
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 51ff3d0a4ee..683df89dbae 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2501,7 +2501,8 @@ static int nilfs_segctor_construct(struct nilfs_sc_info *sci,
 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
 		    nilfs_discontinued(nilfs)) {
 			down_write(&nilfs->ns_sem);
-			req->sb_err = nilfs_commit_super(sbi, 0);
+			req->sb_err = nilfs_commit_super(sbi,
+					nilfs_altsb_need_update(nilfs));
 			up_write(&nilfs->ns_sem);
 		}
 	}
@@ -2689,6 +2690,7 @@ static int nilfs_segctor_thread(void *arg)
 	} else {
 		DEFINE_WAIT(wait);
 		int should_sleep = 1;
+		struct the_nilfs *nilfs;
 
 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
 				TASK_INTERRUPTIBLE);
@@ -2709,6 +2711,9 @@ static int nilfs_segctor_thread(void *arg)
 		finish_wait(&sci->sc_wait_daemon, &wait);
 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
 			   time_after_eq(jiffies, sci->sc_timer->expires));
+		nilfs = sci->sc_sbi->s_nilfs;
+		if (sci->sc_super->s_dirt && nilfs_sb_need_update(nilfs))
+			set_nilfs_discontinued(nilfs);
 	}
 	goto loop;
 
diff --git a/fs/nilfs2/sufile.h b/fs/nilfs2/sufile.h
index a2c4d76c336..0e99e5c0bd0 100644
--- a/fs/nilfs2/sufile.h
+++ b/fs/nilfs2/sufile.h
@@ -28,7 +28,6 @@
 #include <linux/nilfs2_fs.h>
 #include "mdt.h"
 
-#define NILFS_SUFILE_GFP	NILFS_MDT_GFP
 
 static inline unsigned long nilfs_sufile_get_nsegments(struct inode *sufile)
 {
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 151964f0de4..55f3d6b6073 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -50,6 +50,8 @@
 #include <linux/writeback.h>
 #include <linux/kobject.h>
 #include <linux/exportfs.h>
+#include <linux/seq_file.h>
+#include <linux/mount.h>
 #include "nilfs.h"
 #include "mdt.h"
 #include "alloc.h"
@@ -65,7 +67,6 @@ MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
 		   "(NILFS)");
 MODULE_LICENSE("GPL");
 
-static void nilfs_write_super(struct super_block *sb);
 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
 
 /**
@@ -311,9 +312,6 @@ static void nilfs_put_super(struct super_block *sb)
 
 	lock_kernel();
 
-	if (sb->s_dirt)
-		nilfs_write_super(sb);
-
 	nilfs_detach_segment_constructor(sbi);
 
 	if (!(sb->s_flags & MS_RDONLY)) {
@@ -336,63 +334,21 @@ static void nilfs_put_super(struct super_block *sb)
 	unlock_kernel();
 }
 
-/**
- * nilfs_write_super - write super block(s) of NILFS
- * @sb: super_block
- *
- * nilfs_write_super() gets a fs-dependent lock, writes super block(s), and
- * clears s_dirt.  This function is called in the section protected by
- * lock_super().
- *
- * The s_dirt flag is managed by each filesystem and we protect it by ns_sem
- * of the struct the_nilfs.  Lock order must be as follows:
- *
- *   1. lock_super()
- *   2.    down_write(&nilfs->ns_sem)
- *
- * Inside NILFS, locking ns_sem is enough to protect s_dirt and the buffer
- * of the super block (nilfs->ns_sbp[]).
- *
- * In most cases, VFS functions call lock_super() before calling these
- * methods.  So we must be careful not to bring on deadlocks when using
- * lock_super();  see generic_shutdown_super(), write_super(), and so on.
- *
- * Note that order of lock_kernel() and lock_super() depends on contexts
- * of VFS.  We should also note that lock_kernel() can be used in its
- * protective section and only the outermost one has an effect.
- */
-static void nilfs_write_super(struct super_block *sb)
+static int nilfs_sync_fs(struct super_block *sb, int wait)
 {
 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
 	struct the_nilfs *nilfs = sbi->s_nilfs;
-
-	down_write(&nilfs->ns_sem);
-	if (!(sb->s_flags & MS_RDONLY)) {
-		struct nilfs_super_block **sbp = nilfs->ns_sbp;
-		u64 t = get_seconds();
-		int dupsb;
-
-		if (!nilfs_discontinued(nilfs) && t >= nilfs->ns_sbwtime[0] &&
-		    t < nilfs->ns_sbwtime[0] + NILFS_SB_FREQ) {
-			up_write(&nilfs->ns_sem);
-			return;
-		}
-		dupsb = sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
-		nilfs_commit_super(sbi, dupsb);
-	}
-	sb->s_dirt = 0;
-	up_write(&nilfs->ns_sem);
-}
-
-static int nilfs_sync_fs(struct super_block *sb, int wait)
-{
 	int err = 0;
 
-	nilfs_write_super(sb);
-
 	/* This function is called when super block should be written back */
 	if (wait)
 		err = nilfs_construct_segment(sb);
+
+	down_write(&nilfs->ns_sem);
+	if (sb->s_dirt)
+		nilfs_commit_super(sbi, 1);
+	up_write(&nilfs->ns_sem);
+
 	return err;
 }
 
@@ -407,8 +363,7 @@ int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno)
 	list_add(&sbi->s_list, &nilfs->ns_supers);
 	up_write(&nilfs->ns_super_sem);
 
-	sbi->s_ifile = nilfs_mdt_new(
-		nilfs, sbi->s_super, NILFS_IFILE_INO, NILFS_IFILE_GFP);
+	sbi->s_ifile = nilfs_mdt_new(nilfs, sbi->s_super, NILFS_IFILE_INO);
 	if (!sbi->s_ifile)
 		return -ENOMEM;
 
@@ -529,6 +484,26 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	return 0;
 }
 
+static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
+{
+	struct super_block *sb = vfs->mnt_sb;
+	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+
+	if (!nilfs_test_opt(sbi, BARRIER))
+		seq_printf(seq, ",barrier=off");
+	if (nilfs_test_opt(sbi, SNAPSHOT))
+		seq_printf(seq, ",cp=%llu",
+			   (unsigned long long int)sbi->s_snapshot_cno);
+	if (nilfs_test_opt(sbi, ERRORS_RO))
+		seq_printf(seq, ",errors=remount-ro");
+	if (nilfs_test_opt(sbi, ERRORS_PANIC))
+		seq_printf(seq, ",errors=panic");
+	if (nilfs_test_opt(sbi, STRICT_ORDER))
+		seq_printf(seq, ",order=strict");
+
+	return 0;
+}
+
 static struct super_operations nilfs_sops = {
 	.alloc_inode    = nilfs_alloc_inode,
 	.destroy_inode  = nilfs_destroy_inode,
@@ -538,7 +513,7 @@ static struct super_operations nilfs_sops = {
 	/* .drop_inode	  = nilfs_drop_inode, */
 	.delete_inode   = nilfs_delete_inode,
 	.put_super      = nilfs_put_super,
-	.write_super    = nilfs_write_super,
+	/* .write_super    = nilfs_write_super, */
 	.sync_fs        = nilfs_sync_fs,
 	/* .write_super_lockfs */
 	/* .unlockfs */
@@ -546,7 +521,7 @@ static struct super_operations nilfs_sops = {
 	.remount_fs     = nilfs_remount,
 	.clear_inode    = nilfs_clear_inode,
 	/* .umount_begin */
-	/* .show_options */
+	.show_options = nilfs_show_options
 };
 
 static struct inode *
@@ -816,10 +791,15 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 
 	if (sb->s_flags & MS_RDONLY) {
 		if (nilfs_test_opt(sbi, SNAPSHOT)) {
+			down_read(&nilfs->ns_segctor_sem);
 			err = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile,
 						       sbi->s_snapshot_cno);
-			if (err < 0)
+			up_read(&nilfs->ns_segctor_sem);
+			if (err < 0) {
+				if (err == -ENOENT)
+					err = -EINVAL;
 				goto failed_sbi;
+			}
 			if (!err) {
 				printk(KERN_ERR
 				       "NILFS: The specified checkpoint is "
@@ -1127,10 +1107,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
 	 */
 	sd.sbi = nilfs_find_sbinfo(nilfs, !(flags & MS_RDONLY), sd.cno);
 
-	if (!sd.cno)
-		/* trying to get the latest checkpoint.  */
-		sd.cno = nilfs_last_cno(nilfs);
-
 	/*
 	 * Get super block instance holding the nilfs_sb_info struct.
 	 * A new instance is allocated if no existing mount is present or
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 8b888982571..d4168e269c5 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -68,12 +68,11 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
 
 	nilfs->ns_bdev = bdev;
 	atomic_set(&nilfs->ns_count, 1);
-	atomic_set(&nilfs->ns_writer_refcount, -1);
 	atomic_set(&nilfs->ns_ndirtyblks, 0);
 	init_rwsem(&nilfs->ns_sem);
 	init_rwsem(&nilfs->ns_super_sem);
 	mutex_init(&nilfs->ns_mount_mutex);
-	mutex_init(&nilfs->ns_writer_mutex);
+	init_rwsem(&nilfs->ns_writer_sem);
 	INIT_LIST_HEAD(&nilfs->ns_list);
 	INIT_LIST_HEAD(&nilfs->ns_supers);
 	spin_lock_init(&nilfs->ns_last_segment_lock);
@@ -188,23 +187,19 @@ static int nilfs_load_super_root(struct the_nilfs *nilfs,
 	inode_size = nilfs->ns_inode_size;
 
 	err = -ENOMEM;
-	nilfs->ns_dat = nilfs_mdt_new(
-		nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
+	nilfs->ns_dat = nilfs_mdt_new(nilfs, NULL, NILFS_DAT_INO);
 	if (unlikely(!nilfs->ns_dat))
 		goto failed;
 
-	nilfs->ns_gc_dat = nilfs_mdt_new(
-		nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
+	nilfs->ns_gc_dat = nilfs_mdt_new(nilfs, NULL, NILFS_DAT_INO);
 	if (unlikely(!nilfs->ns_gc_dat))
 		goto failed_dat;
 
-	nilfs->ns_cpfile = nilfs_mdt_new(
-		nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
+	nilfs->ns_cpfile = nilfs_mdt_new(nilfs, NULL, NILFS_CPFILE_INO);
 	if (unlikely(!nilfs->ns_cpfile))
 		goto failed_gc_dat;
 
-	nilfs->ns_sufile = nilfs_mdt_new(
-		nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
+	nilfs->ns_sufile = nilfs_mdt_new(nilfs, NULL, NILFS_SUFILE_INO);
 	if (unlikely(!nilfs->ns_sufile))
 		goto failed_cpfile;
 
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 1b9caafb866..20abd55881e 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -37,6 +37,7 @@ enum {
 	THE_NILFS_LOADED,       /* Roll-back/roll-forward has done and
 				   the latest checkpoint was loaded */
 	THE_NILFS_DISCONTINUED,	/* 'next' pointer chain has broken */
+	THE_NILFS_GC_RUNNING,	/* gc process is running */
 };
 
 /**
@@ -50,8 +51,7 @@ enum {
  * @ns_sem: semaphore for shared states
  * @ns_super_sem: semaphore for global operations across super block instances
  * @ns_mount_mutex: mutex protecting mount process of nilfs
- * @ns_writer_mutex: mutex protecting ns_writer attach/detach
- * @ns_writer_refcount: number of referrers on ns_writer
+ * @ns_writer_sem: semaphore protecting ns_writer attach/detach
  * @ns_current: back pointer to current mount
  * @ns_sbh: buffer heads of on-disk super blocks
  * @ns_sbp: pointers to super block data
@@ -100,8 +100,7 @@ struct the_nilfs {
 	struct rw_semaphore	ns_sem;
 	struct rw_semaphore	ns_super_sem;
 	struct mutex		ns_mount_mutex;
-	struct mutex		ns_writer_mutex;
-	atomic_t		ns_writer_refcount;
+	struct rw_semaphore	ns_writer_sem;
 
 	/*
 	 * components protected by ns_super_sem
@@ -197,11 +196,26 @@ static inline int nilfs_##name(struct the_nilfs *nilfs)			\
 THE_NILFS_FNS(INIT, init)
 THE_NILFS_FNS(LOADED, loaded)
 THE_NILFS_FNS(DISCONTINUED, discontinued)
+THE_NILFS_FNS(GC_RUNNING, gc_running)
 
 /* Minimum interval of periodical update of superblocks (in seconds) */
 #define NILFS_SB_FREQ		10
 #define NILFS_ALTSB_FREQ	60  /* spare superblock */
 
+static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
+{
+	u64 t = get_seconds();
+	return t < nilfs->ns_sbwtime[0] ||
+		 t > nilfs->ns_sbwtime[0] + NILFS_SB_FREQ;
+}
+
+static inline int nilfs_altsb_need_update(struct the_nilfs *nilfs)
+{
+	u64 t = get_seconds();
+	struct nilfs_super_block **sbp = nilfs->ns_sbp;
+	return sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
+}
+
 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 struct the_nilfs *find_or_create_nilfs(struct block_device *);
 void put_nilfs(struct the_nilfs *);
@@ -221,34 +235,21 @@ static inline void get_nilfs(struct the_nilfs *nilfs)
 	atomic_inc(&nilfs->ns_count);
 }
 
-static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
-{
-	if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
-		mutex_lock(&nilfs->ns_writer_mutex);
-	return nilfs->ns_writer;
-}
-
-static inline void nilfs_put_writer(struct the_nilfs *nilfs)
-{
-	if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
-		mutex_unlock(&nilfs->ns_writer_mutex);
-}
-
 static inline void
 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 {
-	mutex_lock(&nilfs->ns_writer_mutex);
+	down_write(&nilfs->ns_writer_sem);
 	nilfs->ns_writer = sbi;
-	mutex_unlock(&nilfs->ns_writer_mutex);
+	up_write(&nilfs->ns_writer_sem);
 }
 
 static inline void
 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 {
-	mutex_lock(&nilfs->ns_writer_mutex);
+	down_write(&nilfs->ns_writer_sem);
 	if (sbi == nilfs->ns_writer)
 		nilfs->ns_writer = NULL;
-	mutex_unlock(&nilfs->ns_writer_mutex);
+	up_write(&nilfs->ns_writer_sem);
 }
 
 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)