Theodore Y. Ts'o wrote on 2020/12/3 23:08:
> On Sat, Nov 07, 2020 at 11:58:14PM +0800, Chunguang Xu wrote:
>> From: Chunguang Xu <brookxu@xxxxxxxxxxx>
>>
>> In order to avoid poor search efficiency of system_zone, the
>> system only adds metadata of some sparse group to system_zone.
>> In the meta_bg scenario, the non-sparse group may contain gdt
>> blocks. Perhaps we should add these blocks to system_zone to
>> improve fault tolerance without significantly reducing system
>> performance.
>
>> @@ -226,13 +227,16 @@ int ext4_setup_system_zone(struct super_block *sb)
>>
>> for (i=0; i < ngroups; i++) {
>> cond_resched();
>> - if (ext4_bg_has_super(sb, i) &&
>> - ((i < 5) || ((i % flex_size) == 0))) {
>> - ret = add_system_zone(system_blks,
>> - ext4_group_first_block_no(sb, i),
>> - ext4_bg_num_gdb(sb, i) + 1, 0);
>> - if (ret)
>> - goto err;
>> + if ((i < 5) || ((i % flex_size) == 0)) {
>
> If we're going to do this, why not just drop the above conditional,
> and just always do this logic for all block groups?
Thanks, in the large disk scenario, if we deal with all groups, the
system_zone will be very large, which may reduce performance. I think
the previous method is good, but it needs to be changed slightly, so
that the fault tolerance in the meta_bg scenario can be improved
without the risk of performance degradation.
>> + gd_blks = ext4_bg_has_super(sb, i) +
>> + ext4_bg_num_gdb(sb, i);
>> + if (gd_blks) {
>> + ret = add_system_zone(system_blks,
>> + ext4_group_first_block_no(sb, i),
>> + gd_blks, 0);
>> + if (ret)
>> + goto err;
>> + }
>
> - Ted
>
