On 09/09/2015 04:38 PM, Chris Mason wrote: > On Wed, Sep 09, 2015 at 04:26:58PM -0400, Trond Myklebust wrote: >> On Wed, Sep 9, 2015 at 4:09 PM, Chris Mason <clm@xxxxxx> wrote: >>> On Tue, Sep 08, 2015 at 04:08:43PM -0700, Andy Lutomirski wrote: >>>> On Tue, Sep 8, 2015 at 3:39 PM, Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: >>>>> On Tue, Sep 08, 2015 at 02:45:39PM -0700, Andy Lutomirski wrote: >>>>>> 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. I agree with keeping copy_file_range() simple, especially for the initial merge. Extra stuff can always be added in later :) Anna > > -chris > -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
