On Mon, 3 Feb 2014 13:41:01 -0800, Andrew Morton wrote: > 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. Got it. I missed the recent effort by Vyacheslav which added description on every ioctl in the doucument file. I'll send a patch for this soon. Thanks, Ryusuke Konishi -- 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
