On Tue, May 12, 2015 at 3:24 PM, Christoph Hellwig <h...@infradead.org> wrote: > On Mon, May 11, 2015 at 09:02:54PM +0800, Ming Lei wrote: >> > But those would be user pages. Anyone who passes a kernel page doesn't >> >> Inside kernel it is hard to say one page in page cache is kernel or >> user page, :-) > > Inside the kernel it's easy to say that it's the caller business to > make sure we don't need to carry through hacks like this. > >> > expect it do be dirtied for normal kernel interfaces. >> >> Currently the coming direct IO introduced for loop should be the 1st direct >> read inside kernel, so there isn't the case of passing kernel pages, and >> obviously ITER_BVEC/ITER_KVEC doesn't mean the page is 'kernel' page. >> >> Another direct IO inside kernel is __swap_writepage(), and it is still >> ITER_BVEC and user page. Maybe in the future swap_readpage() >> can use direct IO with BVEC too. > > > Swap will have very different rules to deal with page dirtying as it's > part of the VM subsystem. Again, the caller will now better.
Yes, the caller knows better, that is why I introduce the flag, so the caller can set the flag if it need direct-io to bypass the dirtying, otherwise the caller can just clear the flag. Or I understand you wrong? Thanks, Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
