linux-ext4 - [PATCH 1/5] ext4: when resizing, do not copy gdt blocks for groups that do not have them

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun,  2 Sep 2012 00:51:21 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	xiaoqiangnk@...il.com, "Theodore Ts'o" <tytso@....edu>,
	stable@...r.kernel.org
Subject: [PATCH 1/5] ext4: when resizing, do not copy gdt blocks for groups that do not have them

From: Yongqiang Yang <xiaoqiangnk@...il.com>

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 <xiaoqiangnk@...il.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
Cc: stable@...r.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 41f6ef6..724e250 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -451,6 +451,9 @@ 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;
@@ -493,6 +496,7 @@ 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;
-- 
1.7.12.rc0.22.gcdd159b

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html