On Wed, 17 Apr 2019 08:25:22 +0300 (Adding Al Viro and the linux-fsdevel lists, as at the very least, the manpage for the syscall needs some clarification...)
hello I am trying to fix https://bugzilla.kernel.org/show_bug.cgi?id=202935
So - convince us that it's in fact a "bug" and not a restriction.
I found cause https://github.com/torvalds/linux/blob/master/fs/cifs/cifsfs.c#L1076 not sure is it correct to remove such condition ?
Does the CIFS protocol support copying from a file to another location in the same file? Was it intended to work on *any* filesystem? (For that matter, the manpage for the syscall is unclear on whether having both file descriptors open on the same file is OK or not - for bonus ambiguity points, there's exactly zero discussion of what happens if source and destination overlap destructively).