| Message ID | 201003271916.o2RJGFvn019746@demeter.kernel.org |
|---|---|
| State | New, archived |
| Headers | show |
Index: linux-2.6/fs/ext4/resize.c =================================================================== --- linux-2.6.orig/fs/ext4/resize.c +++ linux-2.6/fs/ext4/resize.c @@ -930,7 +930,8 @@ int ext4_group_add(struct super_block *s 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,
https://bugzilla.kernel.org/show_bug.cgi?id=13549 --- Comment #18 from Eric Sandeen <sandeen@redhat.com> 2010-03-27 19:16:09 --- Reproducer works perfectly, thanks. So here's the issue; sbi->flex_groups[] doesn't get filled out in ext4_fill_flex_info() because: if (groups_per_flex < 2) { sbi->s_log_groups_per_flex = 0; return 1; } but resize is unconditionally doing this in ext4_group_add as long as the FLEX_BG feature is set: atomic_add(input->free_blocks_count, &sbi->s_flex_groups[flex_group].free_blocks); so for a NULL s_flex groups it went boom. Every other access to ->s_flex_groups checks s_log_groups_per_flex first, so this should be the proper fix: This fixes the reproducer, need to double check it on Alessandro's image. -Eric