On Wed, Jul 6, 2011 at 3:21 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > 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? It seems that you both are right. if EXT4_MB_GRP_NEED_INIT() retruns true, it means buddy allocator has not been initialized, and ext4_mb_init_group() initializes the buddy allocator for specified group. Actually, ext4_mb_init_group() initializes UNINIT block bitmap to generate buddy bitmaps. Maybe in trim case, we should consider BLOCK_UNINIT as well. Yongqiang. > > 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 >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Best Wishes Yongqiang Yang -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html