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). sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
