(did I ever reply to this? I meant to ;)) On Fri, 25 Feb 2011 16:52:36 -0500 Steve Rago <sar@xxxxxxxxxxxx> wrote: > This has probably been a problem since day 1 (I ran into this running the 2.4 kernel years ago; finally got around to > fixing it). The problem is that fcntl(fd, F_SETFL, flags|O_SYNC) appears to work, but silently ignores the O_SYNC flag. > Opening the file with O_SYNC works okay, but setting it later on via fcntl doesn't work. > > > Signed-off-by: Steve Rago <sar@xxxxxxxxxxxx> > --- > fs/fcntl.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/fs/fcntl.c b/fs/fcntl.c > index cb10261..afd233a 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -143,7 +143,7 @@ SYSCALL_DEFINE1(dup, unsigned int, fildes) > return ret; > } > > -#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) > +#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME | O_SYNC) Does any standard say that we should do this? http://pubs.opengroup.org/onlinepubs/007908799/xsh/fcntl.html does, I guess. I worry a bit that this change will surprise people. For example, this person: http://koders.com/c/fidA34D8D5EE9AA5D0AB0F3C604678E2E935E5B0246.aspx?s=dupa is going to wonder why his app suddenly got a lot slower! Sadly, the kernel silently ignores invalid set bits in `arg', so we have no reliable way of signaling to the user that our behaviour here changed. I wonder if we should sync the file when someone sets O_SYNC this way. If we don't then there is a period during which we have an fd which has O_SYNC set, but it has pending unwritten data. An O_SYNC fd should never be in such a state! Ho hum. yes, I guess we should apply the patch. But it would have been better to not have screwed this up in the first place! -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
