ext4: add a new function which allocates bitmaps and inode tables

This patch adds a new function named ext4_allocates_group_table()
which allocates block bitmaps, inode bitmaps and inode tables for a
flex groups and is used by resize code.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/resize.c

@@ -189,6 +189,117 @@ static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
 	kfree(flex_gd);
 }
 
+/*
+ * ext4_alloc_group_tables() allocates block bitmaps, inode bitmaps
+ * and inode tables for a flex group.
+ *
+ * This function is used by 64bit-resize.  Note that this function allocates
+ * group tables from the 1st group of groups contained by @flexgd, which may
+ * be a partial of a flex group.
+ *
+ * @sb: super block of fs to which the groups belongs
+ */
+static void ext4_alloc_group_tables(struct super_block *sb,
+				struct ext4_new_flex_group_data *flex_gd,
+				int flexbg_size)
+{
+	struct ext4_new_group_data *group_data = flex_gd->groups;
+	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+	ext4_fsblk_t start_blk;
+	ext4_fsblk_t last_blk;
+	ext4_group_t src_group;
+	ext4_group_t bb_index = 0;
+	ext4_group_t ib_index = 0;
+	ext4_group_t it_index = 0;
+	ext4_group_t group;
+	ext4_group_t last_group;
+	unsigned overhead;
+
+	BUG_ON(flex_gd->count == 0 || group_data == NULL);
+
+	src_group = group_data[0].group;
+	last_group  = src_group + flex_gd->count - 1;
+
+	BUG_ON((flexbg_size > 1) && ((src_group & ~(flexbg_size - 1)) !=
+	       (last_group & ~(flexbg_size - 1))));
+next_group:
+	group = group_data[0].group;
+	start_blk = ext4_group_first_block_no(sb, src_group);
+	last_blk = start_blk + group_data[src_group - group].blocks_count;
+
+	overhead = ext4_bg_has_super(sb, src_group) ?
+		   (1 + ext4_bg_num_gdb(sb, src_group) +
+		    le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
+
+	start_blk += overhead;
+
+	BUG_ON(src_group >= group_data[0].group + flex_gd->count);
+	/* We collect contiguous blocks as much as possible. */
+	src_group++;
+	for (; src_group <= last_group; src_group++)
+		if (!ext4_bg_has_super(sb, src_group))
+			last_blk += group_data[src_group - group].blocks_count;
+		else
+			break;
+
+	/* Allocate block bitmaps */
+	for (; bb_index < flex_gd->count; bb_index++) {
+		if (start_blk >= last_blk)
+			goto next_group;
+		group_data[bb_index].block_bitmap = start_blk++;
+		ext4_get_group_no_and_offset(sb, start_blk - 1, &group, NULL);
+		group -= group_data[0].group;
+		group_data[group].free_blocks_count--;
+		if (flexbg_size > 1)
+			flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
+	}
+
+	/* Allocate inode bitmaps */
+	for (; ib_index < flex_gd->count; ib_index++) {
+		if (start_blk >= last_blk)
+			goto next_group;
+		group_data[ib_index].inode_bitmap = start_blk++;
+		ext4_get_group_no_and_offset(sb, start_blk - 1, &group, NULL);
+		group -= group_data[0].group;
+		group_data[group].free_blocks_count--;
+		if (flexbg_size > 1)
+			flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
+	}
+
+	/* Allocate inode tables */
+	for (; it_index < flex_gd->count; it_index++) {
+		if (start_blk + EXT4_SB(sb)->s_itb_per_group > last_blk)
+			goto next_group;
+		group_data[it_index].inode_table = start_blk;
+		ext4_get_group_no_and_offset(sb, start_blk, &group, NULL);
+		group -= group_data[0].group;
+		group_data[group].free_blocks_count -=
+					EXT4_SB(sb)->s_itb_per_group;
+		if (flexbg_size > 1)
+			flex_gd->bg_flags[group] &= ~EXT4_BG_BLOCK_UNINIT;
+
+		start_blk += EXT4_SB(sb)->s_itb_per_group;
+	}
+
+	if (test_opt(sb, DEBUG)) {
+		int i;
+		group = group_data[0].group;
+
+		printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
+		       "%d groups, flexbg size is %d:\n", flex_gd->count,
+		       flexbg_size);
+
+		for (i = 0; i < flex_gd->count; i++) {
+			printk(KERN_DEBUG "adding %s group %u: %u "
+			       "blocks (%d free)\n",
+			       ext4_bg_has_super(sb, group + i) ? "normal" :
+			       "no-super", group + i,
+			       group_data[i].blocks_count,
+			       group_data[i].free_blocks_count);
+		}
+	}
+}
+
 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 				  ext4_fsblk_t blk)
 {