(did I ever reply to this? I meant to ;))
On Fri, 25 Feb 2011 16:52:36 -0500
Steve Rago 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
> 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 |
> +#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT |
O_NOATIME | O_SYNC)
Does any standard say that we should do this?
I worry a bit that this change will surprise people. For example, this
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
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!