On Friday February 2, [EMAIL PROTECTED] wrote: > Hi, > > For no important reason, I've again looked at those zeroing patches that > Neil did a while back. I've always thought that a simple > `write(fd, NULL, size)` would cause the same sorts of problems.
Yeh, but who in their right mind would do that??? Oh, you did :-) > > Turns out it does. If you first write all 1s into a page, then do the > `write(fd, NULL, size)` at the same position, you end up with all 0s in > the page (test-case available on request). Incredible; surely this > violates the spec? Does it? I guess filling with zeros isn't what one would expect, but you could make a case for it being right. write(fd, 0, size) writes 'size' 0s. Cool. Ok, bad-cool. > > The buffered-write fixes I've got actually fix this properly, but they > don't look like getting merged any time soon. We could do this simple > patch which just reduces the chance of corruption from a certainty down > to a small race. > > Any thoughts? I cannot see why you make a change to fault_in_pages_writeable. Is it just for symmetry? For the rest, it certainly makes sense to return an early -EFAULT if you cannot fault in the page. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/