On Wed, Jul 6, 2011 at 9:09 AM, Kyungmin Park <kmpark@xxxxxxxxxxxxx> wrote:
> Hi Lukas,
>
> During code review batched discard support at ext4. I wonder why do
> you init the uninitialized block group during batched discard.
> As you know uninitialized block group mean that there's no operation
> at these blocks.
Hi Kyungmin,
EXT4_MB_GRP_NEED_INIT() is not the same as EXT4_BG_BLOCK_UNINIT.
The former means that no allocation/free was attempted from the block group
since mount time and the latter means that no allocation happened since mkfs.
> So no need to trim it at all.
So I think it is possible that blocks deleted in previous mount time would
need to be trimmed in this mount time.
Am I right, Lukas?
Amir.
>
> How do you think?
>
> int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
> {
> ...
>
> for (group = first_group; group <= last_group; group++) {
> grp = ext4_get_group_info(sb, group);
> /* We only do this if the grp has never been initialized */
> if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
> ret = ext4_mb_init_group(sb, group);
> if (ret)
> break;
> }
> ...
> }
> ...
> }
>
> Thank you,
> Kyungmin Park
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