Index: linux-stage/fs/ext4/ext4.h
===================================================================
--- linux-stage.orig/fs/ext4/ext4.h
+++ linux-stage/fs/ext4/ext4.h
@@ -1757,6 +1760,9 @@ extern void ext4_add_groupblocks(handle_
 				ext4_fsblk_t block, unsigned long count);
 extern int ext4_trim_fs(struct super_block *, struct fstrim_range *);
 
+extern void ext4_mb_discard_inode_preallocations(struct inode *);
+
+
 /* inode.c */
 int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
 		struct buffer_head *bh, ext4_fsblk_t blocknr);
Index: linux-stage/fs/ext4/ext4_extents.h
===================================================================
--- linux-stage.orig/fs/ext4/ext4_extents.h
+++ linux-stage/fs/ext4/ext4_extents.h
@@ -58,6 +58,12 @@
  */
 #define EXT_STATS_
 
+/*
+ * define EXT4_ALLOC_NEEDED to 0 since block bitmap, group desc. and sb
+ * are now accounted in ext4_ext_calc_credits_for_insert()
+ */
+#define EXT4_ALLOC_NEEDED 0
+#define HAVE_EXT_PREPARE_CB_EXTENT
 
 /*
  * ext4_inode has i_block array (60 bytes total).
@@ -291,6 +297,8 @@ extern int ext4_extent_tree_init(handle_
 extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
 						   int num,
 						   struct ext4_ext_path *path);
+extern int ext4_ext_calc_credits_for_insert(struct inode *,
+					    struct ext4_ext_path *);
 extern int ext4_can_extents_be_merged(struct inode *inode,
 				      struct ext4_extent *ex1,
 				      struct ext4_extent *ex2);
Index: linux-stage/fs/ext4/ext4_jbd2.c
===================================================================
--- linux-stage.orig/fs/ext4/ext4_jbd2.c
+++ linux-stage/fs/ext4/ext4_jbd2.c
@@ -31,6 +31,7 @@ int __ext4_journal_get_write_access(cons
 	}
 	return err;
 }
+EXPORT_SYMBOL(__ext4_journal_get_write_access);
 
 int __ext4_journal_forget(const char *where, handle_t *handle,
 				struct buffer_head *bh)
@@ -107,3 +108,4 @@ int __ext4_handle_dirty_metadata(const c
 	}
 	return err;
 }
+EXPORT_SYMBOL(__ext4_handle_dirty_metadata);
Index: linux-stage/fs/ext4/extents.c
===================================================================
--- linux-stage.orig/fs/ext4/extents.c
+++ linux-stage/fs/ext4/extents.c
@@ -2200,6 +2200,55 @@ int ext4_ext_calc_credits_for_single_ext
 }
 
 /*
+ * This routine returns max. credits extent tree can consume.
+ * It should be OK for low-performance paths like ->writepage()
+ * To allow many writing process to fit a single transaction,
+ * caller should calculate credits under truncate_mutex and
+ * pass actual path.
+ */
+int ext4_ext_calc_credits_for_insert(struct inode *inode,
+				     struct ext4_ext_path *path)
+{
+	int depth, needed;
+
+	if (path) {
+		/* probably there is space in leaf? */
+		depth = path->p_depth;
+		if (le16_to_cpu(path[depth].p_hdr->eh_entries)
+				< le16_to_cpu(path[depth].p_hdr->eh_max))
+			return 1;
+	}
+
+	/*
+	 * given 32bit logical block (4294967296 blocks), max. tree
+	 * can be 4 levels in depth -- 4 * 340^4 == 53453440000.
+	 * let's also add one more level for imbalance.
+	 */
+	depth = 5;
+
+	/* allocation of new data block(s) */
+	needed = 2;
+
+	/*
+	 * tree can be full, so it'd need to grow in depth:
+	 * we need one credit to modify old root, credits for
+	 * new root will be added in split accounting
+	 */
+	needed += 1;
+	/*
+	 * Index split can happen, we'd need:
+	 *    allocate intermediate indexes (bitmap + group)
+	 *  + change two blocks at each level, but root (already included)
+	 */
+	needed += (depth * 2) + (depth * 2);
+
+	/* any allocation modifies superblock */
+	needed += 1;
+
+	return needed;
+}
+
+/*
  * How many index/leaf blocks need to change/allocate to modify nrblocks?
  *
  * if nrblocks are fit in a single extent (chunk flag is 1), then
@@ -4488,3 +4537,12 @@ int ext4_fiemap(struct inode *inode, str
 	return error;
 }
 
+EXPORT_SYMBOL(ext4_ext_search_right);
+EXPORT_SYMBOL(ext4_ext_search_left);
+EXPORT_SYMBOL(ext4_ext_insert_extent);
+EXPORT_SYMBOL(ext4_mb_new_blocks);
+EXPORT_SYMBOL(ext4_ext_calc_credits_for_insert);
+EXPORT_SYMBOL(ext4_mark_inode_dirty);
+EXPORT_SYMBOL(ext4_ext_walk_space);
+EXPORT_SYMBOL(ext4_ext_find_extent);
+EXPORT_SYMBOL(ext4_ext_drop_refs);
Index: linux-stage/fs/ext4/inode.c
===================================================================
--- linux-stage.orig/fs/ext4/inode.c
+++ linux-stage/fs/ext4/inode.c
@@ -5549,6 +5549,7 @@ bad_inode:
 	iget_failed(inode);
 	return ERR_PTR(ret);
 }
+EXPORT_SYMBOL(ext4_iget);
 
 static int ext4_inode_blocks_set(handle_t *handle,
 				struct ext4_inode *raw_inode,
Index: linux-stage/fs/ext4/mballoc.c
===================================================================
--- linux-stage.orig/fs/ext4/mballoc.c
+++ linux-stage/fs/ext4/mballoc.c
@@ -4031,6 +4031,7 @@ repeat:
 	if (ac)
 		kmem_cache_free(ext4_ac_cachep, ac);
 }
+EXPORT_SYMBOL(ext4_discard_preallocations);
 
 /*
  * finds all preallocated spaces and return blocks being freed to them
@@ -5189,3 +5190,6 @@ out:
 	range->len = trimmed * sb->s_blocksize;
 	return ret;
 }
+
+EXPORT_SYMBOL(ext4_free_blocks);
+
Index: linux-stage/fs/ext4/super.c
===================================================================
--- linux-stage.orig/fs/ext4/super.c
+++ linux-stage/fs/ext4/super.c
@@ -137,6 +137,7 @@ __u32 ext4_itable_unused_count(struct su
 		(EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
 		 (__u32)le16_to_cpu(bg->bg_itable_unused_hi) << 16 : 0);
 }
+EXPORT_SYMBOL(ext4_itable_unused_count);
 
 void ext4_block_bitmap_set(struct super_block *sb,
 			   struct ext4_group_desc *bg, ext4_fsblk_t blk)