On 2/25/22 11:36, John Hubbard wrote:
On 2/25/22 04:05, Jan Kara wrote:
...
With having modified fs/direct-io.c and fs/iomap/direct-io.c which
filesystems do you know are missing conversion? Or is it that you just want
to make sure with audit everything is fine? The only fs I could find
unconverted by your changes is ceph. Am I missing something?
Honza
There are a few more filesystems that call iov_iter_get_pages() or
iov_iter_get_pages_alloc(), plus networking things as well, plus some
others that are hard to categorize, such as vhost. So we have:
* ceph
* rds
* cifs
* p9
* net: __zerocopy_sg_from_iter(), tls_setup_from_iter(),
* crypto: af_alg_make_sg() (maybe N/A)
* vmsplice() (as David Hildenbrand mentioned)
* vhost: vhost_scsi_map_to_sgl()
...although...if each filesystem does *not* require custom attention,
then there is another, maybe better approach, which is: factor out an
iovec-only pair of allocators, and transition each subsystem when it's
ready. So:
dio_iov_iter_get_pages()
dio_iov_iter_get_pages_alloc()
That would allow doing this a bit at a time, and without the horrible
CONFIG parameter that is switched over all at once.
The bio_release_pages() still calls unpin_user_page(), though, so that
means that all Direct IO callers would still have to change over at
once.
thanks,
--
John Hubbard
NVIDIA
