On Tue, 4 Feb 2014 01:50:44 +0900 Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> wrote: > With this ioctl the segment usage entries in the SUFILE can be > updated from userspace. > > This is useful, because it allows the userspace GC to modify and update > segment usage entries for specific segments, which enables it to avoid > unnecessary write operations. > > If a segment needs to be cleaned, but there is no or very little > reclaimable space in it, the cleaning operation basically degrades to > a useless moving operation. In the end the only thing that changes is > the location of the data and a timestamp in the segment usage > information. With this ioctl the GC can skip the cleaning and update > the segment usage entries directly instead. > > This is basically a shortcut to cleaning the segment. It is still > necessary to read the segment summary information, but the writing of > the live blocks can be skipped if it's not worth it. Documentation/filesystems/nilfs2.txt should be updated to document the new ioctl. Which we're in there, please check that the ioctl documentation is otherwise complete and up-to-date. These things have a tendency to bitrot. -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
