commit: 6df935ad2fced9033ab52078825fcaf6365f34b7 From: Yongqiang Yang <[email protected]> Date: Wed, 5 Sep 2012 01:25:50 -0400 Subject: 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 <[email protected]> Signed-off-by: "Theodore Ts'o" <[email protected]> Cc: [email protected] --- fs/ext4/resize.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 591f4bd..a0ee26c 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; -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
