From: Eric Sandeen Date: Sun, 16 May 2010 05:00:00 +0000 (-0400) Subject: ext4: check s_log_groups_per_flex in online resize code X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=42007efd569f1cf3bfb9a61da60ef6c2179508ca;p=linux-beck.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 Test-case-by: Christoph Biedl Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" --- diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 5692c48754a0..6df797eb9aeb 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -911,7 +911,8 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input) percpu_counter_add(&sbi->s_freeinodes_counter, EXT4_INODES_PER_GROUP(sb)); - if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { + if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG) && + sbi->s_log_groups_per_flex) { ext4_group_t flex_group; flex_group = ext4_flex_group(sbi, input->group); atomic_add(input->free_blocks_count,