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    SubjectRe: New copyfile system call - discuss before LSF?
    Date
    On Thu, 2013-02-21 at 21:00 +0100, Paolo Bonzini wrote:
    > Il 21/02/2013 15:57, Ric Wheeler ha scritto:
    > >>>
    > >> sendfile64() pretty much already has the right arguments for a
    > >> "copyfile", however it would be nice to add a 'flags' parameter: the
    > >> NFSv4.2 version would use that to specify whether or not to copy file
    > >> metadata.
    > >
    > > That would seem to be enough to me and has the advantage that it is an
    > > relatively obvious extension to something that is at least not totally
    > > unknown to developers.
    > >
    > > Do we need more than that for non-NFS paths I wonder? What does reflink
    > > need or the SCSI mechanism?
    >
    > For virt we would like to be able to specify arbitrary block ranges.
    > Copying an entire file helps some copy operations like storage
    > migration. However, it is not enough to convert the guest's offloaded
    > copies to host-side offloaded copies.

    So how would a system call based on sendfile64() plus my flag parameter
    prevent an underlying implementation from meeting your criterion?

    --
    Trond Myklebust
    Linux NFS client maintainer

    NetApp
    Trond.Myklebust@netapp.com
    www.netapp.com


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