On Fri, Oct 21, 2016 at 10:22:39AM +1100, Dave Chinner wrote: > You do realise that local filesystems can silently change the > location of file data at any point in time, so there is no such > thing as a "stable mapping" of file data to block device addresses > in userspace? > > If you want remote access to the blocks owned and controlled by a > filesystem, then you need to use a filesystem with a remote locking > mechanism to allow co-ordinated, coherent access to the data in > those blocks. Anything else is just asking for ongoing, unfixable > filesystem corruption or data leakage problems (i.e. security > issues). And at least for XFS we have such a mechanism :) E.g. I have a prototype of a pNFS layout that uses XFS+DAX to allow clients to do RDMA directly to XFS files, with the same locking mechanism we use for the current block and scsi layout in xfs_pnfs.c. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>