On Mon, Nov 11, 2019 at 03:19:40AM -0500, Jan Stancek wrote: > > > loff_t length, > > > if (pad) > > > iomap_dio_zero(dio, iomap, pos, fs_block_size - > > > pad); > > > } > > > - return copied ? copied : ret; > > > + return copied ? (loff_t) copied : ret; > > > > I'm a little confused on this proposed fix -- why does casting size_t > > (aka unsigned long) to loff_t (long long) on a 32-bit system change the > > test outcome? > > Ternary operator has a return type and an attempt is made to convert > each of operands to the type of the other. So, in this case "ret" > appears to be converted to type of "copied" first. Both have size of > 4 bytes on 32-bit x86: Sounds like we should use a good old if here to avoid that whole problem spacE: if (copied) return copied; return ret; > size_t copied = 0; > int ret = -14; > long long actor_ret = copied ? copied : ret; > > On x86_64: actor_ret == -14; > On x86 : actor_ret == 4294967282 > > > Does this same diotest4 failure happen with XFS? I ask > > because XFS has been using iomap for directio for ages. > > Yes, it fails on XFS too. Is this a new test? If not why was this never reported? Sounds like we should add this test case to xfstests.
