From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Kleikamp Subject: Re: [PATCH v4 00/31] loop: Issue O_DIRECT aio using bio_vec Date: Fri, 23 Nov 2012 11:33:39 -0600 Message-ID: <50AFB373.8020507@oracle.com> References: <1353537671-26284-1-git-send-email-dave.kleikamp@oracle.com> <20121122194731.GA12057@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Zach Brown , "Maxim V. Patlasov" To: Christoph Hellwig Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:35738 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756027Ab2KWRdx (ORCPT ); Fri, 23 Nov 2012 12:33:53 -0500 In-Reply-To: <20121122194731.GA12057@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 11/22/2012 01:47 PM, Christoph Hellwig wrote: > On Wed, Nov 21, 2012 at 04:40:40PM -0600, Dave Kleikamp wrote: >> It introduces new file ops, read_iter() and write_iter(), that replace the >> aio_read() and aio_write() operations. The iov_iter structure can now contain >> either a user-space iovec or a kernel-space bio_vec. Since it would be >> overly complicated to replace every instance of aio_read() and aio_write(), >> the old operations are not removed, but file systems implementing the new >> ones need not keep the old ones. > > How many instance of the old ones are left? I'd really prefer to make > the full transition very quickly, even if not nessecarily in a single > patchset. The only file systems left are ceph, cifs, fuse and ntfs, but there are the pipe driver and quite a few character devices that implement aio_read and aio_write. It would be easy enough put a read/write_iter wrapper around the non-block devices that return an error or even panic if !iov_iter_has_iovec(iter), but I didn't like the way it looked. (I think "git grep -e \\\.aio_read -e \\\.aio_write" find them all.) If the consensus is to go that route, I'd be happy to work on a follow-up patchset. Shaggy