On Mon, 2021-02-15 at 15:43 +0000, Luis Henriques wrote: > Nicolas Boichat reported an issue when trying to use the > copy_file_range > syscall on a tracefs file. It failed silently because the file > content is > generated on-the-fly (reporting a size of zero) and copy_file_range > needs > to know in advance how much data is present. That explanation makes no sense whatsoever. copy_file_range is a non- atomic operation and so the file can change while being copied. Any determination of 'how much data is present' that is made in advance would therefore be a flaw in the copy process being used (i.e. do_splice_direct()). Does sendfile() also 'issue' in the same way? -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
