On Tue, 6 Jan 2015, Gregory Farnum wrote:
> On Tue, Jan 6, 2015 at 8:44 AM, Sage Weil <[email protected]> wrote:
> > Hey,
> >
> > In an exchange on linux-fsdevel yesterday it became clear that even when
> > FIEMAP isn't buggy it's not a good interface to build a map of sparse
> > files. For example, XFS defrag or other future fs features may muck with
> > fiemap results. One wouldn't expect those things to change whether a file
> > extent is allocated or not allocated, but given what we've seen so far I
> > wouldn't bet on it.
> >
> > Instead, we should use lseek SEEK_DATA/SEEK_HOLE, which is a more natural
> > interface for what we need. This should simply be a matter of replacing
> > the fiemap() method implementation in FileStore.cc, I think.
> >
> > See this thread:
> >
> > http://marc.info/?l=linux-fsdevel&m=142050204317588&w=2
> >
> > The other half of this is we should confirm that xfstests.git has good
> > SEEK_HOLE/SEEK_DATA stress tests (that verify correct results on both
> > recently written, recently synced, and uncached files).
>
> Is there a ticket covering this? :)
Is now :)
http://tracker.ceph.com/issues/10463
sage
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