From: Tao Ma <boyu.mt@xxxxxxxxxx>
Now in online resize, we will add a bunch of groups at one time in
ext4_flex_group_add, so in most cases a lot of group descriptors
will be in the same group block. But in the end of this function,
update_backups will be called for every group descriptor and the
same block will be copied and journalled again and again.
It is really a waste.
So add a old_gdb to store the group block we have already done
the backup and skip the backup until we meet with a new group block.
Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx>
---
fs/ext4/resize.c | 13 +++++++++++--
1 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 019d528..ae2f5fc 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1348,6 +1348,7 @@ exit_journal:
if (!err) {
int i;
+ sector_t old_gdb = 0;
update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
sizeof(struct ext4_super_block));
for (i = 0; i < flex_gd->count; i++, group++) {
@@ -1355,8 +1356,16 @@ exit_journal:
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);
+ /*
+ * only backup the group descriptor block
+ * which hasn't been updated before.
+ */
+ if (old_gdb != gdb_bh->b_blocknr) {
+ update_backups(sb, gdb_bh->b_blocknr,
+ gdb_bh->b_data,
+ gdb_bh->b_size);
+ old_gdb = gdb_bh->b_blocknr;
+ }
}
}
exit:
--
1.7.1
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