ext4: don't call update_backups() multiple times for the same bg
When performing an online resize, we 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.
Fix things so we only update a particular bg descriptor block once and
skip subsequent updates of the same block.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index f21fdbf..7a75e10 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1460,6 +1460,7 @@
EXT4_DESC_PER_BLOCK(sb));
int meta_bg = EXT4_HAS_INCOMPAT_FEATURE(sb,
EXT4_FEATURE_INCOMPAT_META_BG);
+ sector_t old_gdb = 0;
update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
sizeof(struct ext4_super_block), 0);
@@ -1467,8 +1468,11 @@
struct buffer_head *gdb_bh;
gdb_bh = sbi->s_group_desc[gdb_num];
+ if (old_gdb == gdb_bh->b_blocknr)
+ continue;
update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
gdb_bh->b_size, meta_bg);
+ old_gdb = gdb_bh->b_blocknr;
}
}
exit: