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-next>] [day] [month] [year] [list]
Date:	Mon, 24 Sep 2012 23:00:17 +0800
From:	Tao Ma <tm@....ma>
To:	linux-ext4@...r.kernel.org
Subject: [PATCH] ext4: Only call update_backups if necessary in online resize.

From: Tao Ma <boyu.mt@...bao.com>

Now in online resize, we will 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.

So add a old_gdb to store the group block we have already done
the backup and skip the backup until we meet with a new group block.

Signed-off-by: Tao Ma <boyu.mt@...bao.com>
---
 fs/ext4/resize.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 019d528..ae2f5fc 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1348,6 +1348,7 @@ exit_journal:
 
 	if (!err) {
 		int i;
+		sector_t old_gdb = 0;
 		update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
 			       sizeof(struct ext4_super_block));
 		for (i = 0; i < flex_gd->count; i++, group++) {
@@ -1355,8 +1356,16 @@ exit_journal:
 			int gdb_num;
 			gdb_num = group / EXT4_BLOCKS_PER_GROUP(sb);
 			gdb_bh = sbi->s_group_desc[gdb_num];
-			update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
-				       gdb_bh->b_size);
+			/*
+			 * only backup the group descriptor block
+			 * which hasn't been updated before.
+			 */
+			if (old_gdb != gdb_bh->b_blocknr) {
+				update_backups(sb, gdb_bh->b_blocknr,
+					       gdb_bh->b_data,
+					       gdb_bh->b_size);
+				old_gdb = gdb_bh->b_blocknr;
+			}
 		}
 	}
 exit:
-- 
1.7.1

--
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

Powered by blists - more mailing lists