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SubjectRe: [PATCH v4 00/31] loop: Issue O_DIRECT aio using bio_vec
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


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