On 06/06/2024 06:41, Christoph Hellwig wrote:
On Wed, Jun 05, 2024 at 11:48:12AM +0100, John Garry wrote:
I have no strong attachment to that name (atomic).
For both SCSI and NVMe, it's an "atomic" feature and I was basing the
naming on that.
We could have RWF_NOTEARS or RWF_UNTEARABLE_WRITE or RWF_UNTEARABLE or
RWF_UNTORN or similar. Any preference?
No particular preference between any of the option including atomic.
Just mumbling out aloud my thoughts :)
Regardless of the userspace API, I think that the block layer
terminology should match that of the underlying HW technology - so I
would plan to keep "atomic" in the block layer, including request_queue
sysfs limits.
If we used RWF_UNTORN, at some level the "atomic" and "untorn"
terminology would need to interface with one another. If it's going to
be insane to have RWF_UNTORN from userspace being translated into
REQ_ATOMIC, then I could keep RWF_ATOMIC.
Someone please decide ....
For io_uring/rw.c, we have io_write() -> io_rw_init_file(..., WRITE), and
then later we set IOCB_WRITE, so would be neat to use there. But then
do_iter_readv_writev() does not set IOCB_WRITE - I can't imagine that
setting IOCB_WRITE would do any harm there. I see a similar change in
https://lore.kernel.org/linux-fsdevel/167391048988.2311931.1567396746365286847.stgit@xxxxxxxxxxxxxxxxxxxxxx/
AFAICS, setting IOCB_WRITE is quite inconsistent. From browsing through
fsdevel on lore, there was some history in trying to use IOCB_WRITE always
instead of iov_iter direction. Any idea what happened to that?
I'm just getting the feeling that setting IOCB_WRITE in
kiocb_set_rw_flags() is a small part - and maybe counter productive - of a
larger job of fixing IOCB_WRITE usage.
Someone (IIRC Dave H.) want to move it into the iov_iter a while ago.
I think that is a bad idea - the iov_iter is a data container except
for the shoehorned in read/write information doesn't describe the
operation at all. So using the flag in the iocb seems like the better
architecture. But I can understand that you might want to stay out
of all of this, so let's not touch IOCB_WRITE here.
ok
