> On Mar 2, 2017, at 11:07 AM, Christoph Hellwig <hch@xxxxxx> wrote: > > On Thu, Mar 02, 2017 at 11:02:10AM -0500, Olga Kornievskaia wrote: >> Allow nfs_copy_file_range to copy across devices. >> NFSv4.2 inter server to server copy always copies across devices, and >> NFSv4.2 intra server to server copy can copy across devices on the same >> server. >> >> If a file system's fileoperations copy_file_range operation prohibits >> cross-device copies, fall back to do_splice_direct. This is needed for >> nfsd_copy_file_range() which is called by the inter server to server >> destination server acting as an NFS client, and reading the file from >> the source server. > > NAK, we really should not do operations between different superblocks. Can you provide some reasoning as to why? What would it break? The reasoning for including one is to allow for a file system to achieve better performance which seems like a feature that would be of great benefit.
