From 5c41451e164fd068f60d44e3970e3fe2623c2b48 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 19 Jan 2014 16:35:50 -0500
Subject: [PATCH] libext2fs: add ext2fs_block_alloc_stats_range()

This function is more efficient than using ext2fs_block_alloc_stats2()
for each block in a range.  The efficiencies come from being able to
set a block range in the block bitmap at once, and from being update
the block group descriptors once per block group.  Especially now that
we are checksuming the block group descriptors, and we are using red
black trees for the allocation bitmaps, these changes can make a huge
difference in the CPU time used by mke2fs when creating very large
file systems.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 lib/ext2fs/alloc_stats.c | 41 ++++++++++++++++++++++++++++++++++++++++
 lib/ext2fs/ext2fs.h      |  2 ++
 2 files changed, 43 insertions(+)

diff --git a/lib/ext2fs/alloc_stats.c b/lib/ext2fs/alloc_stats.c
index adec3636..1f58e001 100644
--- a/lib/ext2fs/alloc_stats.c
+++ b/lib/ext2fs/alloc_stats.c
@@ -106,3 +106,44 @@ void ext2fs_set_block_alloc_stats_callback(ext2_filsys fs,
 
 	fs->block_alloc_stats = func;
 }
+
+void ext2fs_block_alloc_stats_range(ext2_filsys fs, blk64_t blk,
+				    blk_t num, int inuse)
+{
+#ifndef OMIT_COM_ERR
+	if (blk + num > ext2fs_blocks_count(fs->super)) {
+		com_err("ext2fs_block_alloc_stats_range", 0,
+			"Illegal block range: %llu (%u) ",
+			(unsigned long long) blk, num);
+		return;
+	}
+#endif
+	if (inuse == 0)
+		return;
+	if (inuse > 0) {
+		ext2fs_mark_block_bitmap_range2(fs->block_map, blk, num);
+		inuse = 1;
+	} else {
+		ext2fs_unmark_block_bitmap_range2(fs->block_map, blk, num);
+		inuse = -1;
+	}
+	while (num) {
+		int group = ext2fs_group_of_blk2(fs, blk);
+		blk64_t last_blk = ext2fs_group_last_block2(fs, group);
+		blk_t n = num;
+
+		if (blk + num > last_blk)
+			n = last_blk - blk + 1;
+
+		ext2fs_bg_free_blocks_count_set(fs, group,
+			ext2fs_bg_free_blocks_count(fs, group) -
+			inuse*n/EXT2FS_CLUSTER_RATIO(fs));
+		ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
+		ext2fs_group_desc_csum_set(fs, group);
+		ext2fs_free_blocks_count_add(fs->super, -inuse * n);
+		blk += n;
+		num -= n;
+	}
+	ext2fs_mark_super_dirty(fs);
+	ext2fs_mark_bb_dirty(fs);
+}
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 1e07f88b..47340dd7 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -683,6 +683,8 @@ void ext2fs_inode_alloc_stats2(ext2_filsys fs, ext2_ino_t ino,
 			       int inuse, int isdir);
 void ext2fs_block_alloc_stats(ext2_filsys fs, blk_t blk, int inuse);
 void ext2fs_block_alloc_stats2(ext2_filsys fs, blk64_t blk, int inuse);
+void ext2fs_block_alloc_stats_range(ext2_filsys fs, blk64_t blk,
+				    blk_t num, int inuse);
 
 /* alloc_tables.c */
 extern errcode_t ext2fs_allocate_tables(ext2_filsys fs);