Hi Miao, On Mon, November 12, 2012 at 03:21 (+0100), Miao Xie wrote: > On fri, 09 Nov 2012 10:33:52 +1100, Chris Samuel wrote: >> On 08/11/12 20:55, Miao Xie wrote: >> >>> In kernel, qgroupid 0 is a special number when we run the quota group >>> limit command. >>> >>> So, we should not be able to create a quota group whose id is 0, >>> otherwise the kernel can't deal with it. Fix it. >> >> This is probably a stupid question - but if its not meant to be possible >> to create such a thing shouldn't this be fixed in the kernel (as well as >> here) to reject attempts from user space to create it? >> >> Otherwise it's possible for a non-aware program (or a user who is >> playing) to still create it. > > Right. It also should be fixed in the kernel side, the patch is coming. > > But since we know which number is valid or not, it is better that we also > check > the arguments in the user tool before they are passed into the kernel. So, we > can avoid trapping into the kernel, which will waste time, and output the > error > information as soon as possible.
Have the kernel return with errno EINVAL is the way everyone else (I know about) does this. I would avoid doing a check more than once where ever possible. Primarily, because duplicating checks is error prone and in case of a kernel interface it complicates future changes. -Jan -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
