IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it
was created for legacy selected buffer and has been emptied. It violates
the requirement that most of the field should stay stable after publish.
Always reallocate it instead.

Cc: stable@vger.kernel.org
Reported-by: Pumpkin Chang <pumpkin@devco.re>
Fixes: 2fcabce2d7d34 ("io_uring: disallow mixed provided buffer group registrations")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull io_uring updates from Jens Axboe:
 "Not a lot in terms of features this time around, mostly just cleanups
  and code consolidation:

   - Support for PI meta data read/write via io_uring, with NVMe and
     SCSI covered

   - Cleanup the per-op structure caching, making it consistent across
     various command types

   - Consolidate the various user mapped features into a concept called
     regions, making the various users of that consistent

   - Various cleanups and fixes"

* tag 'for-6.14/io_uring-20250119' of git://git.kernel.dk/linux: (56 commits)
  io_uring/fdinfo: fix io_uring_show_fdinfo() misuse of ->d_iname
  io_uring: reuse io_should_terminate_tw() for cmds
  io_uring: Factor out a function to parse restrictions
  io_uring/rsrc: require cloned buffers to share accounting contexts
  io_uring: simplify the SQPOLL thread check when cancelling requests
  io_uring: expose read/write attribute capability
  io_uring/rw: don't gate retry on completion context
  io_uring/rw: handle -EAGAIN retry at IO completion time
  io_uring/rw: use io_rw_recycle() from cleanup path
  io_uring/rsrc: simplify the bvec iter count calculation
  io_uring: ensure io_queue_deferred() is out-of-line
  io_uring/rw: always clear ->bytes_done on io_async_rw setup
  io_uring/rw: use NULL for rw->free_iovec assigment
  io_uring/rw: don't mask in f_iocb_flags
  io_uring/msg_ring: Drop custom destructor
  io_uring: Move old async data allocation helper to header
  io_uring/rw: Allocate async data through helper
  io_uring/net: Allocate msghdr async data through helper
  io_uring/uring_cmd: Allocate async data through generic helper
  io_uring/poll: Allocate apoll with generic alloc_cache helper
  ...

For non-pollable files, buffer ring consumption will commit upfront.
This is fine, but io_ring_buffer_select() will return the address of the
buffer after having committed it. For incrementally consumed buffers,
this is incorrect as it will modify the buffer address.

Store the pre-committed value and return that. If that isn't done, then
the initial part of the buffer is not used and the application will
correctly assume the content arrived at the start of the userspace
buffer, but the kernel will have put it later in the buffer. Or it can
cause a spurious -EFAULT returned in the CQE, depending on the buffer
size. As bounds are suitably checked for doing the actual IO, no adverse
side effects are possible - it's just a data misplacement within the
existing buffer.

Reported-by: Gwendal Fernet <gwendalfernet@gmail.com>
Cc: stable@vger.kernel.org
Fixes: ae98dbf43d75 ("io_uring/kbuf: add support for incremental buffer consumption")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Shifting reg.bgid << IORING_OFF_PBUF_SHIFT results in a promotion
from __u16 to a 32 bit signed integer, this is then sign extended
to a 64 bit unsigned long on 64 bit architectures. If reg.bgid is
greater than 0x7fff then this leads to a sign extended result where
all the upper 32 bits of mmap_offset are set to 1. Fix this by
casting reg.bgid to the same type as mmap_offset before performing
the shift.

Fixes: ef62de3c4ad5 ("io_uring/kbuf: use region api for pbuf rings")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20241204153923.401674-1-colin.i.king@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

All mapped memory is now backed by regions and we can unify and clean
up io_region_validate_mmap() and io_uring_mmap(). Extract a function
looking up a region, the rest of the handling should be generic and just
needs the region.

There is one more ring type specific code, i.e. the mmaping size
truncation quirk for IORING_OFF_[S,C]Q_RING, which is left as is.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f5e1eda1562bfd34276de07465525ae5f10e1e84.1732886067.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Convert internal parts of the provided buffer ring managment to the
region API. It's the last non-region mapped ring we have, so it also
kills a bunch of now unused memmap.c helpers.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6c40cf7beaa648558acd4d84bc0fb3279a35d74b.1732886067.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

struct io_buffer_list refcounting was needed for RCU based sync with
mmap, now  we can kill it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4a9cc54bf0077bb2bf2f3daf917549ddd41080da.1732886067.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

A preparation / cleanup patch simplifying the buf ring - mmap
synchronisation. Instead of relying on RCU, which is trickier, do it by
grabbing the mmap_lock when when anyone tries to publish or remove a
registered buffer to / from ->io_bl_xa.

Modifications of the xarray should always be protected by both
->uring_lock and ->mmap_lock, while lookups should hold either of them.
While a struct io_buffer_list is in the xarray, the mmap related fields
like ->flags and ->buf_pages should stay stable.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/af13bde56ee1a26bcaefaa9aad37a9ea318a590e.1732886067.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull io_uring updates from Jens Axboe:

 - NAPI fixes and cleanups (Pavel, Olivier)

 - Add support for absolute timeouts (Pavel)

 - Fixes for io-wq/sqpoll affinities (Felix)

 - Efficiency improvements for dealing with huge pages (Chenliang)

 - Support for a minwait mode, where the application essentially has two
   timouts - one smaller one that defines the batch timeout, and the
   overall large one similar to what we had before. This enables
   efficient use of batching based on count + timeout, while still
   working well with periods of less intensive workloads

 - Use ITER_UBUF for single segment sends

 - Add support for incremental buffer consumption. Right now each
   operation will always consume a full buffer. With incremental
   consumption, a recv/read operation only consumes the part of the
   buffer that it needs to satisfy the operation

 - Add support for GCOV for io_uring, to help retain a high coverage of
   test to code ratio

 - Fix regression with ocfs2, where an odd -EOPNOTSUPP wasn't correctly
   converted to a blocking retry

 - Add support for cloning registered buffers from one ring to another

 - Misc cleanups (Anuj, me)

* tag 'for-6.12/io_uring-20240913' of git://git.kernel.dk/linux: (35 commits)
  io_uring: add IORING_REGISTER_COPY_BUFFERS method
  io_uring/register: provide helper to get io_ring_ctx from 'fd'
  io_uring/rsrc: add reference count to struct io_mapped_ubuf
  io_uring/rsrc: clear 'slot' entry upfront
  io_uring/io-wq: inherit cpuset of cgroup in io worker
  io_uring/io-wq: do not allow pinning outside of cpuset
  io_uring/rw: drop -EOPNOTSUPP check in __io_complete_rw_common()
  io_uring/rw: treat -EOPNOTSUPP for IOCB_NOWAIT like -EAGAIN
  io_uring/sqpoll: do not allow pinning outside of cpuset
  io_uring/eventfd: move refs to refcount_t
  io_uring: remove unused rsrc_put_fn
  io_uring: add new line after variable declaration
  io_uring: add GCOV_PROFILE_URING Kconfig option
  io_uring/kbuf: add support for incremental buffer consumption
  io_uring/kbuf: pass in 'len' argument for buffer commit
  Revert "io_uring: Require zeroed sqe->len on provided-buffers send"
  io_uring/kbuf: move io_ring_head_to_buf() to kbuf.h
  io_uring/kbuf: add io_kbuf_commit() helper
  io_uring/kbuf: shrink nr_iovs/mode in struct buf_sel_arg
  io_uring: wire up min batch wake timeout
  ...

io_provided_buffers_select() returns 0 to indicate success, but it should
be returning 1 to indicate that 1 vec was mapped. This causes peeking
to fail with classic provided buffers, and while that's not a use case
that anyone should use, it should still work correctly.

The end result is that no buffer will be selected, and hence a completion
with '0' as the result will be posted, without a buffer attached.

Fixes: 35c8711c8fc4 ("io_uring/kbuf: add helpers for getting/peeking multiple buffers")
Signed-off-by: Jens Axboe <axboe@kernel.dk>