A previous commit aborted mapping more for a non-incremental ring for
bundle peeking, but depending on where in the process this peeking
happened, it would not necessarily prevent a retry by the user. That can
create gaps in the received/read data.

Add struct buf_sel_arg->partial_map, which can pass this information
back. The networking side can then map that to internal state and use it
to gate retry as well.

Since this necessitates a new flag, change io_sr_msg->retry to a
retry_flags member, and store both the retry and partial map condition
in there.

Cc: stable@vger.kernel.org
Fixes: 26ec15e4b0c1 ("io_uring/kbuf: don't truncate end buffer for multiple buffer peeks")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If peeking a bunch of buffers, normally io_ring_buffers_peek() will
truncate the end buffer. This isn't optimal as presumably more data will
be arriving later, and hence it's better to stop with the last full
buffer rather than truncate the end buffer.

Cc: stable@vger.kernel.org
Fixes: 35c8711c8fc4 ("io_uring/kbuf: add helpers for getting/peeking multiple buffers")
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The buffer ID for a provided buffer is an unsigned short, and hence
there can only be 64k added to any given buffer list before having
duplicate BIDs. Cap the legacy provided buffers at 64k in the list.
This is mostly to prevent silly stall reports from syzbot, which
likes to dump tons of buffers into a list and then have kernels with
lockdep and kasan churning through them and hitting long wait times
for buffer pruning at ring exit time.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

IOU_COMPLETE is more descriptive, in that it explicitly says that the
return value means "please post a completion for this request". This
patch completes the transition from IOU_OK to IOU_COMPLETE, replacing
existing IOU_OK users.

This is a purely mechanical change.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Combine IORING_OP_PROVIDE_BUFFERS and IORING_OP_REMOVE_BUFFERS
->issue(), so that we can deduplicate ring locking and list lookups.
This way we further reduce code for legacy provided buffers. Locking is
also separated from buffer related handling, which makes it a bit
simpler with label jumps.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f61af131622ad4337c2fb9f7c453d5b0102c7b90.1747150490.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

__io_remove_buffers used for two purposes, the first is removing
buffers for non ring based lists, which implies that it can be called
multiple times for the same list. And the second is for destroying
lists, which is not perfectly reentrable for ring based lists.

It's confusing, so just have a helper for the legacy pbuf buffer
removal, make sure it's not called for ring pbuf, and open code all ring
pbuf destruction into io_put_bl().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0ae416b099d311ad23f285cea02f2c94c8ae9a6c.1747150490.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The size in prep is calculated by io_provide_buffers_prep(), so remove
the recomputation a few lines after.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7c97206561b74fce245cb22449c6082d2e066844.1747150490.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bl and free_bl variables in io_register_pbuf_ring() always point to the
same list since we started to reallocate the pre-existent list. Drop
free_bl.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d45c3342d74c9030f99376c777a4b3d59089074d.1747150490.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Make use of mem_is_zero() for reserved fields checking.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/11fe27b7a831329bcdb4ea087317ef123ba7c171.1747150490.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Follow the non-ringed pbuf struct io_buffer_list allocations and account
it against the memcg. There is low chance of that being an actual
problem as ring provided buffer should either pin user memory or
allocate it, which is already accounted.

Cc: stable@vger.kernel.org # 6.1
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3985218b50d341273cafff7234e1a7e6d0db9808.1747150490.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>