From: Eric Sandeen <sandeen@redhat.com>
Date: Sun, 16 May 2010 05:00:00 +0000 (-0400)
Subject: ext4: check s_log_groups_per_flex in online resize code
X-Git-Tag: v2.6.35-rc1~39^2~32
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=42007efd569f1cf3bfb9a61da60ef6c2179508ca;p=pandora-kernel.git

ext4: check s_log_groups_per_flex in online resize code

If groups_per_flex < 2, sbi->s_flex_groups[] doesn't get filled out,
and every other access to this first tests s_log_groups_per_flex;
same thing needs to happen in resize or we'll wander off into
a null pointer when doing an online resize of the file system.

Thanks to Christoph Biedl, who came up with the trivial testcase:

# truncate --size 128M fsfile
# mkfs.ext3 -F fsfile
# tune2fs -O extents,uninit_bg,dir_index,flex_bg,huge_file,dir_nlink,extra_isize fsfile
# e2fsck -yDf -C0 fsfile
# truncate --size 132M fsfile
# losetup /dev/loop0 fsfile
# mount /dev/loop0 mnt
# resize2fs -p /dev/loop0

	https://bugzilla.kernel.org/show_bug.cgi?id=13549

Reported-by: Alessandro Polverini <alex@nibbles.it>
Test-case-by: Christoph Biedl  <bugzilla.kernel.bpeb@manchmal.in-ulm.de>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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