Re: Is there a "make hole" (truncate in middle) syscall?
From: Mike Fedyk
Date: Thu Dec 04 2003 - 21:04:31 EST
On Fri, Dec 05, 2003 at 01:42:13AM +0200, Szakacsits Szabolcs wrote:
> On Thu, 4 Dec 2003, Andy Isaacson wrote:
> > I'm curious -- does NTFS implement sparse files?
> Since Win2000 (NTFS 3.0+). Also many recently discussed features like
> file/directory/volume level compression/encryption, undelete, power of 2
> block sizes between 512-64kB, etc.
That gives us some possibilities for 2.7:
Ext2 has undelete support, but that information is overwritten on unlink by
ext3, so ext3 won't work with the undelete utilities. How do the other
filesystems fare in this regard?
o per file compression
Ext2/3 has a flag for it, but support hasn't been implemented.
o per file encryption (can use a user space helper for policy)
Reiser4 plans to have a plugin that will support this.
What about the others?
o make hole support
And my personal favorite:
o pagecache coherent defrag (on live filesystems)
Andrew Morton wrote a patch for this a while back but since there were no
userspace utilities, and it was ext3 specific, it wasn't merged, and nothing
AFAIK has happened with it since.
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