> Everybody know that writeback mode for ext3 is potentially result in > stale data in case of unclean umount. The same is true for ext4 with > nodelalloc. > But as far as i can see things is getting better in case of delalloc. > In case of delalloc we have following calltrace: > [writeback thread] > ext4_da_writepages > journal_start() > ext4_map_blocks() -> real block allocation > mpage_da_submit_io() -> submit_bh() -> submit_bio() > journal_stop() > So journal will be closed only after data was issued. > And if journal->j_dev == journal->j_fs_dev (which is usually the case) > data will be serialized with metadata. So it looks like it is impassible > to see stale data even after unclean umount. > > Do I miss something? May be this was already discussed before, > if so please post a link to previous discussion. Well, we turn off delayed allocation when a filesystem gets close to ENOSPC so it's not completely reliable. But besides this, your observation looks correct to me. Honza -- Jan Kara <jack@xxxxxxx> SuSE CR Labs -- 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
