From c52b5ceefc4d1a07d69680727d01b683869f3ba8 Mon Sep 17 00:00:00 2001 From: Yongqiang Yang Date: Wed, 5 Sep 2012 01:25:50 -0400 Subject: [PATCH] ext4: don't copy non-existent gdt blocks when resizing The resize code was copying blocks at the beginning of each block group in order to copy the superblock and block group descriptor table (gdt) blocks. This was, unfortunately, being done even for block groups that did not have super blocks or gdt blocks. This is a complete waste of perfectly good I/O bandwidth, to skip writing those blocks for sparse bg's. Signed-off-by: Yongqiang Yang Signed-off-by: "Theodore Ts'o" Cc: stable@vger.kernel.org --- fs/ext4/resize.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 591f4bda1146d..a0ee26c23dd83 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -456,6 +456,9 @@ static int setup_new_flex_group_blocks(struct super_block *sb, gdblocks = ext4_bg_num_gdb(sb, group); start = ext4_group_first_block_no(sb, group); + if (!ext4_bg_has_super(sb, group)) + goto handle_itb; + /* Copy all of the GDT blocks into the backup in this group */ for (j = 0, block = start + 1; j < gdblocks; j++, block++) { struct buffer_head *gdb; @@ -498,6 +501,7 @@ static int setup_new_flex_group_blocks(struct super_block *sb, goto out; } +handle_itb: /* Initialize group tables of the grop @group */ if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED)) goto handle_bb; -- 2.39.5