First kernel patch

真正意义上的第一个kernel patch（之前给documentation有一个patch，但那不算coding:)。值得纪念的日子，留博一篇。

在ext4 w/o journal模式下，ext4 online resize的两个ioctl不应该提交清空journal的要求，否则会造成一个null pointer的kernel oops。

commit ac046f1d6121ccdda6db66bd88acd52418f489b2
Author: Peng Tao
Date: Mon Jul 13 09:30:17 2009 -0400

ext4: fix null handler of ioctls in no journal mode

The EXT4_IOC_GROUP_ADD and EXT4_IOC_GROUP_EXTEND ioctls should not
flush the journal in no_journal mode. Otherwise, running resize2fs on
a mounted no_journal partition triggers the following error messages:

BUG: unable to handle kernel NULL pointer dereference at 00000014
IP: [] _spin_lock+0x8/0x19
*pde = 00000000
Oops: 0002 [#1] SMP

Signed-off-by: Peng Tao
Signed-off-by: "Theodore Ts'o"