This is a note to let you know that I've just added the patch titled
ext4: don't copy non-existent gdt blocks when resizing
to the 3.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-don-t-copy-non-existent-gdt-blocks-when-resizing.patch
and it can be found in the queue-3.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 6df935ad2fced9033ab52078825fcaf6365f34b7 Mon Sep 17 00:00:00 2001
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
From: Yongqiang Yang <[email protected]>
commit 6df935ad2fced9033ab52078825fcaf6365f34b7 upstream.
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]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/ext4/resize.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -456,6 +456,9 @@ static int setup_new_flex_group_blocks(s
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(s
goto out;
}
+handle_itb:
/* Initialize group tables of the grop @group */
if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
goto handle_bb;
Patches currently in stable-queue which might be from [email protected] are
queue-3.6/ext4-don-t-copy-non-existent-gdt-blocks-when-resizing.patch
queue-3.6/ext4-ignore-last-group-w-o-enough-space-when-resizing-instead-of-bug-ing.patch
queue-3.6/ext4-avoid-duplicate-writes-of-the-backup-bg-descriptor-blocks.patch
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