[ 066/120] ext4: avoid duplicate writes of the backup bg descriptor blocks

Greg Kroah-Hartman
2012-10-11T01:29:28Z

From: Yongqiang Yang <xiaoqiangnk@gmail.com>

commit 2ebd1704ded88a8ae29b5f3998b13959c715c4be upstream.

The resize code was needlessly writing the backup block group
descriptor blocks multiple times (once per block group) during an
online resize.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/resize.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1302,13 +1302,15 @@ exit_journal:
err = err2;

if (!err) {
- int i;
+ int gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
+ int gdb_num_end = ((group + flex_gd->count - 1) /
+ EXT4_DESC_PER_BLOCK(sb));
+
update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
sizeof(struct ext4_super_block));
- for (i = 0; i < flex_gd->count; i++, group++) {
+ for (; gdb_num <= gdb_num_end; gdb_num++) {
struct buffer_head *gdb_bh;
- int gdb_num;
- gdb_num = group / EXT4_BLOCKS_PER_GROUP(sb);
+
gdb_bh = sbi->s_group_desc[gdb_num];
update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
gdb_bh->b_size);