On Wed, Sep 09, 2015 at 04:26:58PM -0400, Trond Myklebust wrote:
On Wed, Sep 9, 2015 at 4:09 PM, Chris Mason [off-list ref] wrote:
quoted
On Tue, Sep 08, 2015 at 04:08:43PM -0700, Andy Lutomirski wrote:
quoted
On Tue, Sep 8, 2015 at 3:39 PM, Darrick J. Wong [off-list ref] wrote:
quoted
On Tue, Sep 08, 2015 at 02:45:39PM -0700, Andy Lutomirski wrote:
quoted
What I meant by this was: if you ask for "regular copy", you may end
up with a reflink anyway. Anyway, how can you reflink a range and
have the contents *not* be the same?
reflink forcibly remaps fd_dest's range to fd_src's range. If they didn't
match before, they will afterwards.
dedupe remaps fd_dest's range to fd_src's range only if they match, of course.
Perhaps I should have said "...if the contents are the same before the call"?
Oh, I see.
Can we have a clean way to figure out whether two file ranges are the
same in a way that allows false negatives? I.e. return 1 if the
ranges are reflinks of each other and 0 if not? Pretty please? I've
implemented that in the past on btrfs by syncing the ranges and then
comparing FIEMAP output, but that's hideous.
I'd almost rather have a separate call, maybe unshare_file_range()?
Doesn't it make more sense to put that functionality in fallocate()?
That works too, I'm just hoping to keep the copy_file_range stuff
simple.
-chris
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html