On 2/5/12 10:55 AM, Andreas Dilger wrote: > On 2012-02-05, at 9:36, Eric Sandeen <sandeen@xxxxxxxxxx> wrote: >> On 2/5/12 3:33 AM, Ron Yorston wrote: >>> Eric Sandeen wrote: >>>> Now that ext4, xfs, & ocfs2 can support punch hole, a tool to >>>> "re-sparsify" a file by punching out ranges of 0s might be in order. >>>> >>>> I'll see if util-linux wants it after it gets beat into shape. >>>> (or did a tool like this already exist and I missed it?) >> >> Matthias' suggestion of adding SEEK_HOLE/SEEK_DATA makes very good sense too. > > I thought about this, but if SEEK_HOLE/SEEK_DATA (or FIEMAP) worked, > then the file would already be sparse, so I don't think that will > help in this case... But only if other tools originally used them, and there will probably be plenty of cases where they don't, or legacy files, or .... >> I should also untie the read/zero buffer size from the minimum hole size, >> we should do optimal IO sizes regardless of the minimum hole size desired... > > Definitely. 4kB IO is a killer for large files. yeah, it was a quick hack, I'll try to fix that up. (OTOH for large files you man not want a 4k hole granularity either) -Eric > Cheers, Andreas -- 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
