Can be done in one of two ways:

1) Regular file descriptor, just fget()
2) Registered ring, index our own table for that

In preparation for adding another register use of needing to get a ctx
from a file descriptor, abstract out this helper and use it in the main
register syscall as well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Currently there's a single ring owner of a mapped buffer, and hence the
reference count will always be 1 when it's torn down and freed. However,
in preparation for being able to link io_mapped_ubuf to different spots,
add a reference count to manage the lifetime of it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

No functional changes in this patch, but clearing the slot pointer
earlier will be required by a later change.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The io worker threads are userland threads that just never exit to the
userland. By that, they are also assigned to a cgroup (the group of the
creating task).

When creating a new io worker, this worker should inherit the cpuset
of the cgroup.

Fixes: da64d6db ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240910171157.166423-3-felix.moessbauer@siemens.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

The io worker threads are userland threads that just never exit to the
userland. By that, they are also assigned to a cgroup (the group of the
creating task).

When changing the affinity of the io_wq thread via syscall, we must only
allow cpumasks within the limits defined by the cpuset controller of the
cgroup (if enabled).

Fixes: da64d6db ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240910171157.166423-2-felix.moessbauer@siemens.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

A recent change ensured that the necessary -EOPNOTSUPP -> -EAGAIN
transformation happens inline on both the reader and writer side,
and hence there's no need to check for both of these anymore on
the completion handler side.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Some file systems, ocfs2 in this case, will return -EOPNOTSUPP for
an IOCB_NOWAIT read/write attempt. While this can be argued to be
correct, the usual return value for something that requires blocking
issue is -EAGAIN.

A refactoring io_uring commit dropped calling kiocb_done() for
negative return values, which is otherwise where we already do that
transformation. To ensure we catch it in both spots, check it in
__io_read() itself as well.
Reported-by: Robert Sander <r.sander@heinlein-support.de>
Link: https://fosstodon.org/@gurubert@mastodon.gurubert.de/113112431889638440
Cc: stable@vger.kernel.org
Fixes: a08d195b ("io_uring/rw: split io_read() into a helper")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The submit queue polling threads are userland threads that just never
exit to the userland. When creating the thread with IORING_SETUP_SQ_AFF,
the affinity of the poller thread is set to the cpu specified in
sq_thread_cpu. However, this CPU can be outside of the cpuset defined
by the cgroup cpuset controller. This violates the rules defined by the
cpuset controller and is a potential issue for realtime applications.

In b7ed6d8ffd6 we fixed the default affinity of the poller thread, in
case no explicit pinning is required by inheriting the one of the
creating task. In case of explicit pinning, the check is more
complicated, as also a cpu outside of the parent cpumask is allowed.
We implemented this by using cpuset_cpus_allowed (that has support for
cgroup cpusets) and testing if the requested cpu is in the set.

Fixes: 37d1e2e3 ("io_uring: move SQPOLL thread io-wq forked worker")
Cc: stable@vger.kernel.org # 6.1+
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240909150036.55921-1-felix.moessbauer@siemens.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

atomic_t for the struct io_ev_fd references and there are no issues with
it. While the ref getting and putting for the eventfd code is somewhat
performance critical for cases where eventfd signaling is used (news
flash, you should not...), it probably doesn't warrant using an atomic_t
for this. Let's just move to it to refcount_t to get the added
protection of over/underflows.

Link: https://lore.kernel.org/lkml/202409082039.hnsaIJ3X-lkp@intel.com/Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409082039.hnsaIJ3X-lkp@intel.com/Signed-off-by: Jens Axboe <axboe@kernel.dk>

rsrc_put_fn is declared but never used, remove it.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Link: https://lore.kernel.org/r/20240902062134.136387-3-anuj20.g@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Fixes checkpatch warning
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Link: https://lore.kernel.org/r/20240902062134.136387-2-anuj20.g@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

If GCOV is enabled and this option is set, it enables code coverage
profiling of the io_uring subsystem. Only use this for test purposes,
as it will impact the runtime performance.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

By default, any recv/read operation that uses provided buffers will
consume at least 1 buffer fully (and maybe more, in case of bundles).
This adds support for incremental consumption, meaning that an
application may add large buffers, and each read/recv will just consume
the part of the buffer that it needs.

For example, let's say an application registers 1MB buffers in a
provided buffer ring, for streaming receives. If it gets a short recv,
then the full 1MB buffer will be consumed and passed back to the
application. With incremental consumption, only the part that was
actually used is consumed, and the buffer remains the current one.

This means that both the application and the kernel needs to keep track
of what the current receive point is. Each recv will still pass back a
buffer ID and the size consumed, the only difference is that before the
next receive would always be the next buffer in the ring. Now the same
buffer ID may return multiple receives, each at an offset into that
buffer from where the previous receive left off. Example:

Application registers a provided buffer ring, and adds two 32K buffers
to the ring.

Buffer1 address: 0x1000000 (buffer ID 0)
Buffer2 address: 0x2000000 (buffer ID 1)

A recv completion is received with the following values:

cqe->res	0x1000	(4k bytes received)
cqe->flags	0x11	(CQE_F_BUFFER|CQE_F_BUF_MORE set, buffer ID 0)

and the application now knows that 4096b of data is available at
0x1000000, the start of that buffer, and that more data from this buffer
will be coming. Now the next receive comes in:

cqe->res	0x2010	(8k bytes received)
cqe->flags	0x11	(CQE_F_BUFFER|CQE_F_BUF_MORE set, buffer ID 0)

which tells the application that 8k is available where the last
completion left off, at 0x1001000. Next completion is:

cqe->res	0x5000	(20k bytes received)
cqe->flags	0x1	(CQE_F_BUFFER set, buffer ID 0)

and the application now knows that 20k of data is available at
0x1003000, which is where the previous receive ended. CQE_F_BUF_MORE
isn't set, as no more data is available in this buffer ID. The next
completion is then:

cqe->res	0x1000	(4k bytes received)
cqe->flags	0x10001	(CQE_F_BUFFER|CQE_F_BUF_MORE set, buffer ID 1)

which tells the application that buffer ID 1 is now the current one,
hence there's 4k of valid data at 0x2000000. 0x2001000 will be the next
receive point for this buffer ID.

When a buffer will be reused by future CQE completions,
IORING_CQE_BUF_MORE will be set in cqe->flags. This tells the application
that the kernel isn't done with the buffer yet, and that it should expect
more completions for this buffer ID. Will only be set by provided buffer
rings setup with IOU_PBUF_RING INC, as that's the only type of buffer
that will see multiple consecutive completions for the same buffer ID.
For any other provided buffer type, any completion that passes back
a buffer to the application is final.

Once a buffer has been fully consumed, the buffer ring head is
incremented and the next receive will indicate the next buffer ID in the
CQE cflags.

On the send side, the application can manage how much data is sent from
an existing buffer by setting sqe->len to the desired send length.

An application can request incremental consumption by setting
IOU_PBUF_RING_INC in the provided buffer ring registration. Outside of
that, any provided buffer ring setup and buffer additions is done like
before, no changes there. The only change is in how an application may
see multiple completions for the same buffer ID, hence needing to know
where the next receive will happen.

Note that like existing provided buffer rings, this should not be used
with IOSQE_ASYNC, as both really require the ring to remain locked over
the duration of the buffer selection and the operation completion. It
will consume a buffer otherwise regardless of the size of the IO done.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

In preparation for needing the consumed length, pass in the length being
completed. Unused right now, but will be used when it is possible to
partially consume a buffer.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This reverts commit 79996b45.

Revert the change that restricts a send provided buffer to be zero, so
it will always consume the whole buffer. This is strictly needed for
partial consumption, as the send may very well be a subset of the
current buffer. In fact, that's the intended use case.

For non-incremental provided buffer rings, an application should set
sqe->len carefully to avoid the potential issue described in the
reverted commit. It is recommended that '0' still be set for len for
that case, if the application is set on maintaining more than 1 send
inflight for the same socket. This is somewhat of a nonsensical thing
to do.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

In preparation for using this helper in kbuf.h as well, move it there and
turn it into a macro.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Committing the selected ring buffer is currently done in three different
spots, combine it into a helper and just call that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nr_iovs is capped at 1024, and mode only has a few low values. We can
safely make them u16, in preparation for adding a few more members.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Expose min_wait_usec in io_uring_getevents_arg, replacing the pad member
that is currently in there. The value is in usecs, which is explained in
the name as well.

Note that if min_wait_usec and a normal timeout is used in conjunction,
the normal timeout is still relative to the base time. For example, if
min_wait_usec is set to 100 and the normal timeout is 1000, the max
total time waited is still 1000. This also means that if the normal
timeout is shorter than min_wait_usec, then only the min_wait_usec will
take effect.

See previous commit for an explanation of how this works.

IORING_FEAT_MIN_TIMEOUT is added as a feature flag for this, as
applications doing submit_and_wait_timeout() style operations will
generally not see the -EINVAL from the wait side as they return the
number of IOs submitted. Only if no IOs are submitted will the -EINVAL
bubble back up to the application.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Waiting for events with io_uring has two knobs that can be set:

1) The number of events to wake for
2) The timeout associated with the event

Waiting will abort when either of those conditions are met, as expected.

This adds support for a third event, which is associated with the number
of events to wait for. Applications generally like to handle batches of
completions, and right now they'd set a number of events to wait for and
the timeout for that. If no events have been received but the timeout
triggers, control is returned to the application and it can wait again.
However, if the application doesn't have anything to do until events are
reaped, then it's possible to make this waiting more efficient.

For example, the application may have a latency time of 50 usecs and
wanting to handle a batch of 8 requests at the time. If it uses 50 usecs
as the timeout, then it'll be doing 20K context switches per second even
if nothing is happening.

This introduces the notion of min batch wait time. If the min batch wait
time expires, then we'll return to userspace if we have any events at all.
If none are available, the general wait time is applied. Any request
arriving after the min batch wait time will cause waiting to stop and
return control to the application.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

In preparation for having two distinct timeouts and avoid waking the
task if we don't need to.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

In preparation for expanding how we handle waits, move the actual
schedule and schedule_timeout() handling into a helper.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Rather than need to pass in 2 or 3 separate arguments, add a struct
to encapsulate the timeout and sigset_t parts of waiting. In preparation
for adding another argument for waiting.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add a new registration opcode IORING_REGISTER_CLOCK, which allows the
user to select which clock id it wants to use with CQ waiting timeouts.
It only allows a subset of all posix clocks and currently supports
CLOCK_MONOTONIC and CLOCK_BOOTTIME.
Suggested-by: Lewis Baker <lewissbaker@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/98f2bc8a3c36cdf8f0e6a275245e81e903459703.1723039801.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

In addition to current relative timeouts for the waiting loop, where the
timespec argument specifies the maximum time it can wait for, add
support for the absolute mode, with the value carrying a CLOCK_MONOTONIC
absolute time until which we should return control back to the user.
Suggested-by: Lewis Baker <lewissbaker@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4d5b74d67ada882590b2e42aa3aa7117bbf6b55f.1723039801.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Remove io_napi_adjust_timeout() and move the adjustments out of the
common path into __io_napi_busy_loop(). Now the limit it's calculated
based on struct io_wait_queue::timeout, for which we query current time
another time. The overhead shouldn't be a problem, it's a polling path,
however that can be optimised later by additionally saving the delta
time value in io_cqring_wait().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/88e14686e245b3b42ff90a3c4d70895d48676206.1723039801.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

we don't need to set ->napi_prefer_busy_poll if we're not going to poll,
do the checks first and all polling preparation after.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2ad7ede8cc7905328fc62e8c3805fdb11635ae0b.1723039801.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

We could just move these two and save some space, but in preparation
for adding another flag, turn them into flags first.

This saves 8 bytes in struct io_buffer_list, making it exactly half
a cacheline on 64-bit archs now rather than 40 bytes.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Just like what is being done on the recv side, if we only map a single
segment, then use ITER_UBUF for mapping it. That's more efficient than
using an ITER_IOVEC.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

req->buf_list is assigned higher up and is safe to use as we remain
within a locked region, as is the 'bl' variable itself from which it
was assigned. To improve readability, use 'bl' directly rather than
get it from the io_kiocb, if we need to increment the head directly
in the buffer selection path. This makes it readily apparent that
it's the same io_buffer_list being used.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

reverse the order of the element evaluation in an if statement.

for many users that are not using iopoll, the iopoll_list will always
evaluate to false after having made a memory access whereas to_submit is
very likely already loaded in a register.
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/052ca60b5c49e7439e4b8bd33bfab4a09d36d3d6.1722374371.git.olivier@trillion01.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Add support for checking and coalescing multi-hugepage-backed fixed
buffers. The coalescing optimizes both time and space consumption caused
by mapping and storing multi-hugepage fixed buffers.

A coalescable multi-hugepage buffer should fully cover its folios
(except potentially the first and last one), and these folios should
have the same size. These requirements are for easier processing later,
also we need same size'd chunks in io_import_fixed for fast iov_iter
adjust.
Signed-off-by: Chenliang Li <cliang01.li@samsung.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20240731090133.4106-3-cliang01.li@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Store the folio shift and folio mask into imu struct and use it in
iov_iter adjust, as we will have non PAGE_SIZE'd chunks if a
multi-hugepage buffer get coalesced.
Signed-off-by: Chenliang Li <cliang01.li@samsung.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20240731090133.4106-2-cliang01.li@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

This info may be useful when attempting to debug a problem involving a
ring using the NAPI feature.

Here is an example of the output:
ip-172-31-39-89 /proc/772/fdinfo # cat 14
pos:	0
flags:	02000002
mnt_id:	16
ino:	10243
SqMask:	0xff
SqHead:	633
SqTail:	633
CachedSqHead:	633
CqMask:	0x3fff
CqHead:	430250
CqTail:	430250
CachedCqTail:	430250
SQEs:	0
CQEs:	0
SqThread:	885
SqThreadCpu:	0
SqTotalTime:	52793826
SqWorkTime:	3590465
UserFiles:	0
UserBufs:	0
PollList:
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=6, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=6, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
  op=10, task_works=0
CqOverflowList:
NAPI:	enabled
napi_busy_poll_to:	1
napi_prefer_busy_poll:	true
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bb184f8b62703ddd3e6e19eae7ab6c67b97e1e10.1722293317.git.olivier@trillion01.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

Pull bcachefs fixes from Kent Overstreet:

 - assorted syzbot fixes

 - some upgrade fixes for old (pre 1.0) filesystems

 - fix for moving data off a device that was switched to durability=0
   after data had been written to it.

 - nocow deadlock fix

 - fix for new rebalance_work accounting

* tag 'bcachefs-2024-08-24' of git://evilpiepirate.org/bcachefs: (28 commits)
  bcachefs: Fix rebalance_work accounting
  bcachefs: Fix failure to flush moves before sleeping in copygc
  bcachefs: don't use rht_bucket() in btree_key_cache_scan()
  bcachefs: add missing inode_walker_exit()
  bcachefs: clear path->should_be_locked in bch2_btree_key_cache_drop()
  bcachefs: Fix double assignment in check_dirent_to_subvol()
  bcachefs: Fix refcounting in discard path
  bcachefs: Fix compat issue with old alloc_v4 keys
  bcachefs: Fix warning in bch2_fs_journal_stop()
  fs/super.c: improve get_tree() error message
  bcachefs: Fix missing validation in bch2_sb_journal_v2_validate()
  bcachefs: Fix replay_now_at() assert
  bcachefs: Fix locking in bch2_ioc_setlabel()
  bcachefs: fix failure to relock in btree_node_fill()
  bcachefs: fix failure to relock in bch2_btree_node_mem_alloc()
  bcachefs: unlock_long() before resort in journal replay
  bcachefs: fix missing bch2_err_str()
  bcachefs: fix time_stats_to_text()
  bcachefs: Fix bch2_bucket_gens_init()
  bcachefs: Fix bch2_trigger_alloc assert
  ...

Pull smb server fixes from Steve French:

 - query directory flex array fix

 - fix potential null ptr reference in open

 - fix error message in some open cases

 - two minor cleanups

* tag '6.11-rc5-server-fixes' of git://git.samba.org/ksmbd:
  smb/server: update misguided comment of smb2_allocate_rsp_buf()
  smb/server: remove useless assignment of 'file_present' in smb2_open()
  smb/server: fix potential null-ptr-deref of lease_ctx_info in smb2_open()
  smb/server: fix return value of smb2_open()
  ksmbd: the buffer of smb2 query dir response has at least 1 byte

Pull s390 fixes from Vasily Gorbik:

 - Fix KASLR base offset to account for symbol offsets in the vmlinux
   ELF file, preventing tool breakages like the drgn debugger

 - Fix potential memory corruption of physmem_info during kernel
   physical address randomization

 - Fix potential memory corruption due to overlap between the relocated
   lowcore and identity mapping by correctly reserving lowcore memory

 - Fix performance regression and avoid randomizing identity mapping
   base by default

 - Fix unnecessary delay of AP bus binding complete uevent to prevent
   startup lag in KVM guests using AP

* tag 's390-6.11-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/boot: Fix KASLR base offset off by __START_KERNEL bytes
  s390/boot: Avoid possible physmem_info segment corruption
  s390/ap: Refine AP bus bindings complete processing
  s390/mm: Pin identity mapping base to zero
  s390/mm: Prevent lowcore vs identity mapping overlap

Pull SCSI fixes from James Bottomley:
 "The important core fix is another tweak to our discard discovery
  issues. The off by 512 in logical block count seems bad, but in fact
  the inline was only ever used in debug prints, which is why no-one
  noticed"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: sd: Do not attempt to configure discard unless LBPME is set
  scsi: MAINTAINERS: Add header files to SCSI SUBSYSTEM
  scsi: ufs: qcom: Add UFSHCD_QUIRK_BROKEN_LSDBS_CAP for SM8550 SoC
  scsi: ufs: core: Add a quirk for handling broken LSDBS field in controller capabilities register
  scsi: core: Fix the return value of scsi_logical_block_count()
  scsi: MAINTAINERS: Update HiSilicon SAS controller driver maintainer

rebalance_work was keying off of the presence of rebelance_opts in the
extent - but that was incorrect, we keep those around after rebalance
for indirect extents since the inode's options are not directly
available

Fixes: 20ac515a ("bcachefs: bch_acct_rebalance_work")
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>