On Mon, May 24, 2010 at 9:05 AM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: >> The "at least" idea makes sense. So, I'd change my recommendation to: >> >> Pass the buffer size in and out in bytes (for consistency with other >> APIs). Round the input (F_SETPIPE_SZ) value up as required by the >> implementation. For the output (F_GETPIPE_SZ) value do one of the >> following: >> a) Return the value given on input. >> b) Return the rounded up value actually used by the kernel. >> >> I suspect (b) might be more useful: if an application cares enough >> about pipe size to want to change it, then at least some such >> applications might care to know exactly the size that the kernel used. >> (And: I can't see any downside to (b).) > > b definitely, since it's the real size (plus then we don't have to track > the passed in size). Okay. >> One other comment about the interface. We have >> >> if (!capable(CAP_SYS_ADMIN) && arg > pipe_max_pages) >> return -EINVAL; >> >> The usual error on a capability denied is EPERM. Please change. > > Right, that looks like a thinko. > > I'll submit a patch changing it to bytes and the agreed API and fix this > -Eerror. Thanks for your comments and suggestions! Thanks. And of course you are welcome. (Please CC linux-api@vger on this patche (and all patches that change the API/ABI.) Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface" http://blog.man7.org/ -- 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
