From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 28 Aug 2008 14:20:43 +0000 (-0400)
Subject: Further optimize journal placement for flex_bg filesystems
X-Git-Tag: v1.41.1~14
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=b55d73985cc7a33e2b57161e5ea1a5a2ad1bff9c;p=tools%2Fe2fsprogs.git

Further optimize journal placement for flex_bg filesystems

If the number of block groups is greater than half the flex_bg size,
the journal we be placed in the flex_bg super-group which is closest
to the mid-point of the filesystem, and in the first free block group
beyond where the metadata for the flex_bg is stored.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/lib/ext2fs/mkjournal.c b/lib/ext2fs/mkjournal.c
index 96b574e..f5a9dba 100644
--- a/lib/ext2fs/mkjournal.c
+++ b/lib/ext2fs/mkjournal.c
@@ -275,7 +275,7 @@ static errcode_t write_journal_inode(ext2_filsys fs, ext2_ino_t journal_ino,
 				     blk_t size, int flags)
 {
 	char			*buf;
-	dgrp_t			group, start, end, i;
+	dgrp_t			group, start, end, i, log_flex;
 	errcode_t		retval;
 	struct ext2_inode	inode;
 	struct mkjournal_struct	es;
@@ -311,7 +311,17 @@ static errcode_t write_journal_inode(ext2_filsys fs, ext2_ino_t journal_ino,
 	 */
 	group = ext2fs_group_of_blk(fs, (fs->super->s_blocks_count -
 					 fs->super->s_first_data_block) / 2);
-	start = (group > 0) ? group-1 : group;
+	log_flex = 1 << fs->super->s_log_groups_per_flex;
+	if (fs->super->s_log_groups_per_flex && (group > log_flex)) {
+		group = group & ~(log_flex - 1);
+		while ((group < fs->group_desc_count) &&
+		       fs->group_desc[group].bg_free_blocks_count == 0)
+			group++;
+		if (group == fs->group_desc_count)
+			group = 0;
+		start = group;
+	} else
+		start = (group > 0) ? group-1 : group;
 	end = ((group+1) < fs->group_desc_count) ? group+1 : group;
 	group = start;
 	for (i=start+1; i <= end; i++)