ext4: add a structure which will be used by 64bit-resize interface

This patch adds a structure which will be used by 64bit-resize interface.
Two functions which allocate and destroy the structure respectively are
added.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/resize.c

@@ -134,6 +134,61 @@ static int verify_group_input(struct super_block *sb,
 	return err;
 }
 
+/*
+ * ext4_new_flex_group_data is used by 64bit-resize interface to add a flex
+ * group each time.
+ */
+struct ext4_new_flex_group_data {
+	struct ext4_new_group_data *groups;	/* new_group_data for groups
+						   in the flex group */
+	__u16 *bg_flags;			/* block group flags of groups
+						   in @groups */
+	ext4_group_t count;			/* number of groups in @groups
+						 */
+};
+
+/*
+ * alloc_flex_gd() allocates a ext4_new_flex_group_data with size of
+ * @flexbg_size.
+ *
+ * Returns NULL on failure otherwise address of the allocated structure.
+ */
+static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
+{
+	struct ext4_new_flex_group_data *flex_gd;
+
+	flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
+	if (flex_gd == NULL)
+		goto out3;
+
+	flex_gd->count = flexbg_size;
+
+	flex_gd->groups = kmalloc(sizeof(struct ext4_new_group_data) *
+				  flexbg_size, GFP_NOFS);
+	if (flex_gd->groups == NULL)
+		goto out2;
+
+	flex_gd->bg_flags = kmalloc(flexbg_size * sizeof(__u16), GFP_NOFS);
+	if (flex_gd->bg_flags == NULL)
+		goto out1;
+
+	return flex_gd;
+
+out1:
+	kfree(flex_gd->groups);
+out2:
+	kfree(flex_gd);
+out3:
+	return NULL;
+}
+
+static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
+{
+	kfree(flex_gd->bg_flags);
+	kfree(flex_gd->groups);
+	kfree(flex_gd);
+}
+
 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 				  ext4_fsblk_t blk)
 {