On 21/11/14 18:09, Andy Lutomirski wrote: > On Fri, Nov 21, 2014 at 6:17 AM, Pádraig Brady <P@xxxxxxxxxxxxxx> wrote: >> If 'a' and 'b' are hardlinks, then the command `mv a b & mv b a` >> can result in both being removed as mv needs to emulate the >> move with an unlink of the source file. This can only be done >> without races in the kernel and so mv was recently changed >> to not allow this operation at all. mv could safely reintroduce >> this feature by leveraging a new flag for renameat() for which >> an illustrative/untested patch is attached. > > ISTM the issue is that rename(2) does nothing if the source and dest > are hardlinks to each other. Is that intentional? I don't see that > behavior as required in the POSIX rename docs. It's surprising and annoying that existing systems do this, but they're conforming to the wording of POSIX I thinkg as it says that rename() does nothing when the source and dest _file_ is the same. What POSIX really meant I suppose was _file name_. Eric, perhaps an adjustment could be proposed to POSIX, as I can't see anything relying on the current behavior? > If we indeed need to keep that behavior around for legacy reasons, > then can we at least give RENAME_REMOVE a better name? Definitely not attached to the name :) Let's see if we can change it without a flag, though I guess that would mean that mv on older systems would silently do nothing in this case. thanks, Pádraig. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
