io_uring/fs: consider link->flags when getting path for LINKAT

In order for `AT_EMPTY_PATH` to work as expected, the fact
that the user wants that behavior needs to make it to `getname_flags`
or it will return ENOENT.

Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc: <stable@vger.kernel.org>
Link: https://github.com/axboe/liburing/issues/995
Signed-off-by: Charles Mirabile <cmirabil@redhat.com>
Link: https://lore.kernel.org/r/20231120105545.1209530-1-cmirabil@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/fs: remove sqe->rw_flags checking from LINKAT

This is unionized with the actual link flags, so they can of course be
set and they will be evaluated further down. If not we fail any LINKAT
that has to set option flags.

Fixes: cf30da90bc3a ("io_uring: add support for IORING_OP_LINKAT")
Cc: stable@vger.kernel.org
Reported-by: Thomas Leonard <talex5@gmail.com>
Link: https://github.com/axboe/liburing/issues/955
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: for requests that require async, force it

Some requests require being run async as they do not support
non-blocking. Instead of trying to issue these requests, getting -EAGAIN
and then queueing them for async issue, rather just force async upfront.

Add WARN_ON_ONCE to make sure surprising code paths do not come up,
however in those cases the bug would end up being a blocking
io_uring_enter(2) which should not be critical.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20230127135227.3646353-3-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: make io_kiocb_to_cmd() typesafe

We need to make sure (at build time) that struct io_cmd_data is not
casted to a structure that's larger.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Link: https://lore.kernel.org/r/c024cdf25ae19fc0319d4180e2298bade8ed17b8.1660201408.git.metze@samba.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: kill extra io_uring_types.h includes

io_uring/io_uring.h already includes io_uring_types.h, no need to
include it every time. Kill it in a bunch of places, it prepares us for
following patches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/94d8c943fbe0ef949981c508ddcee7fc1c18850f.1655384063.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: split out filesystem related operations

This splits out renameat, unlinkat, mkdirat, symlinkat, and linkat.

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