Commit Graph

140 Commits

Author SHA1 Message Date
Jens Axboe
5e559561a8 io_uring: ensure registered buffer import returns the IO length
A test case was reported where two linked reads with registered buffers
failed the second link always. This is because we set the expected value
of a request in req->result, and if we don't get this result, then we
fail the dependent links. For some reason the registered buffer import
returned -ERROR/0, while the normal import returns -ERROR/length. This
broke linked commands with registered buffers.

Fix this by making io_import_fixed() correctly return the mapped length.

Cc: stable@vger.kernel.org # v5.3
Reported-by: 李通洲 <carter.li@eoitek.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-13 16:15:14 -07:00
Pavel Begunkov
5683e5406e io_uring: Fix getting file for timeout
For timeout requests io_uring tries to grab a file with specified fd,
which is usually stdin/fd=0.
Update io_op_needs_file()

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-13 15:25:57 -07:00
Jens Axboe
93bd25bb69 io_uring: make timeout sequence == 0 mean no sequence
Currently we make sequence == 0 be the same as sequence == 1, but that's
not super useful if the intent is really to have a timeout that's just
a pure timeout.

If the user passes in sqe->off == 0, then don't apply any sequence logic
to the request, let it purely be driven by the timeout specified.

Reported-by: 李通洲 <carter.li@eoitek.com>
Reviewed-by: 李通洲 <carter.li@eoitek.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-12 00:18:51 -07:00
Jens Axboe
6873e0bd6a io_uring: ensure we clear io_kiocb->result before each issue
We use io_kiocb->result == -EAGAIN as a way to know if we need to
re-submit a polled request, as -EAGAIN reporting happens out-of-line
for IO submission failures. This field is cleared when we originally
allocate the request, but it isn't reset when we retry the submission
from async context. This can cause issues where we think something
needs a re-issue, but we're really just reading stale data.

Reset ->result whenever we re-prep a request for polled submission.

Cc: stable@vger.kernel.org
Fixes: 9e645e1105 ("io_uring: add support for sqe links")
Reported-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-30 14:45:22 -06:00
Jens Axboe
044c1ab399 io_uring: don't touch ctx in setup after ring fd install
syzkaller reported an issue where it looks like a malicious app can
trigger a use-after-free of reading the ctx ->sq_array and ->rings
value right after having installed the ring fd in the process file
table.

Defer ring fd installation until after we're done reading those
values.

Fixes: 75b28affdd ("io_uring: allocate the two rings together")
Reported-by: syzbot+6f03d895a6cd0d06187f@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-28 09:15:33 -06:00
Pavel Begunkov
7b20238d28 io_uring: Fix leaked shadow_req
io_queue_link_head() owns shadow_req after taking it as an argument.
By not freeing it in case of an error, it can leak the request along
with taken ctx->refs.

Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-27 21:29:18 -06:00
Jens Axboe
2b2ed9750f io_uring: fix bad inflight accounting for SETUP_IOPOLL|SETUP_SQTHREAD
We currently assume that submissions from the sqthread are successful,
and if IO polling is enabled, we use that value for knowing how many
completions to look for. But if we overflowed the CQ ring or some
requests simply got errored and already completed, they won't be
available for polling.

For the case of IO polling and SQTHREAD usage, look at the pending
poll list. If it ever hits empty then we know that we don't have
anymore pollable requests inflight. For that case, simply reset
the inflight count to zero.

Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-25 10:58:53 -06:00
Jens Axboe
498ccd9eda io_uring: used cached copies of sq->dropped and cq->overflow
We currently use the ring values directly, but that can lead to issues
if the application is malicious and changes these values on our behalf.
Created in-kernel cached versions of them, and just overwrite the user
side when we update them. This is similar to how we treat the sq/cq
ring tail/head updates.

Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-25 10:58:45 -06:00
Pavel Begunkov
935d1e4590 io_uring: Fix race for sqes with userspace
io_ring_submit() finalises with
1. io_commit_sqring(), which releases sqes to the userspace
2. Then calls to io_queue_link_head(), accessing released head's sqe

Reorder them.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-25 09:02:01 -06:00
Pavel Begunkov
fb5ccc9878 io_uring: Fix broken links with offloading
io_sq_thread() processes sqes by 8 without considering links. As a
result, links will be randomely subdivided.

The easiest way to fix it is to call io_get_sqring() inside
io_submit_sqes() as do io_ring_submit().

Downsides:
1. This removes optimisation of not grabbing mm_struct for fixed files
2. It submitting all sqes in one go, without finer-grained sheduling
with cq processing.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-25 09:01:59 -06:00
Pavel Begunkov
84d55dc5b9 io_uring: Fix corrupted user_data
There is a bug, where failed linked requests are returned not with
specified @user_data, but with garbage from a kernel stack.

The reason is that io_fail_links() uses req->user_data, which is
uninitialised when called from io_queue_sqe() on fail path.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-25 09:01:58 -06:00
zhangyi (F)
a1f58ba46f io_uring: correct timeout req sequence when inserting a new entry
The sequence number of the timeout req (req->sequence) indicate the
expected completion request. Because of each timeout req consume a
sequence number, so the sequence of each timeout req on the timeout
list shouldn't be the same. But now, we may get the same number (also
incorrect) if we insert a new entry before the last one, such as submit
such two timeout reqs on a new ring instance below.

                    req->sequence
 req_1 (count = 2):       2
 req_2 (count = 1):       2

Then, if we submit a nop req, req_2 will still timeout even the nop req
finished. This patch fix this problem by adjust the sequence number of
each reordered reqs when inserting a new entry.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-23 22:09:56 -06:00
zhangyi (F)
ef03681ae8 io_uring : correct timeout req sequence when waiting timeout
The sequence number of reqs on the timeout_list before the timeout req
should be adjusted in io_timeout_fn(), because the current timeout req
will consumes a slot in the cq_ring and cq_tail pointer will be
increased, otherwise other timeout reqs may return in advance without
waiting for enough wait_nr.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-23 22:09:56 -06:00
Jens Axboe
bc808bced3 io_uring: revert "io_uring: optimize submit_and_wait API"
There are cases where it isn't always safe to block for submission,
even if the caller asked to wait for events as well. Revert the
previous optimization of doing that.

This reverts two commits:

bf7ec93c64
c576666863

Fixes: c576666863 ("io_uring: optimize submit_and_wait API")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-23 22:09:56 -06:00
Linus Torvalds
d418d07005 for-linus-2019-10-18
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Merge tag 'for-linus-2019-10-18' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - NVMe pull request from Keith that address deadlocks, double resets,
   memory leaks, and other regression.

 - Fixup elv_support_iosched() for bio based devices (Damien)

 - Fixup for the ahci PCS quirk (Dan)

 - Socket O_NONBLOCK handling fix for io_uring (me)

 - Timeout sequence io_uring fixes (yangerkun)

 - MD warning fix for parameter default_layout (Song)

 - blkcg activation fixes (Tejun)

 - blk-rq-qos node deletion fix (Tejun)

* tag 'for-linus-2019-10-18' of git://git.kernel.dk/linux-block:
  nvme-pci: Set the prp2 correctly when using more than 4k page
  io_uring: fix logic error in io_timeout
  io_uring: fix up O_NONBLOCK handling for sockets
  md/raid0: fix warning message for parameter default_layout
  libata/ahci: Fix PCS quirk application
  blk-rq-qos: fix first node deletion of rq_qos_del()
  blkcg: Fix multiple bugs in blkcg_activate_policy()
  io_uring: consider the overflow of sequence for timeout req
  nvme-tcp: fix possible leakage during error flow
  nvmet-loop: fix possible leakage during error flow
  block: Fix elv_support_iosched()
  nvme-tcp: Initialize sk->sk_ll_usec only with NET_RX_BUSY_POLL
  nvme: Wait for reset state when required
  nvme: Prevent resets during paused controller state
  nvme: Restart request timers in resetting state
  nvme: Remove ADMIN_ONLY state
  nvme-pci: Free tagset if no IO queues
  nvme: retain split access workaround for capability reads
  nvme: fix possible deadlock when nvme_update_formats fails
2019-10-18 22:29:36 -04:00
yangerkun
8b07a65ad3 io_uring: fix logic error in io_timeout
If ctx->cached_sq_head < nxt_sq_head, we should add UINT_MAX to tmp, not
tmp_nxt.

Fixes: 5da0fb1ab3 ("io_uring: consider the overflow of sequence for timeout req")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-17 15:49:15 -06:00
Jens Axboe
491381ce07 io_uring: fix up O_NONBLOCK handling for sockets
We've got two issues with the non-regular file handling for non-blocking
IO:

1) We don't want to re-do a short read in full for a non-regular file,
   as we can't just read the data again.
2) For non-regular files that don't support non-blocking IO attempts,
   we need to punt to async context even if the file is opened as
   non-blocking. Otherwise the caller always gets -EAGAIN.

Add two new request flags to handle these cases. One is just a cache
of the inode S_ISREG() status, the other tells io_uring that we always
need to punt this request to async context, even if REQ_F_NOWAIT is set.

Cc: stable@vger.kernel.org
Reported-by: Hrvoje Zeba <zeba.hrvoje@gmail.com>
Tested-by: Hrvoje Zeba <zeba.hrvoje@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-17 15:49:11 -06:00
yangerkun
5da0fb1ab3 io_uring: consider the overflow of sequence for timeout req
Now we recalculate the sequence of timeout with 'req->sequence =
ctx->cached_sq_head + count - 1', judge the right place to insert
for timeout_list by compare the number of request we still expected for
completion. But we have not consider about the situation of overflow:

1. ctx->cached_sq_head + count - 1 may overflow. And a bigger count for
the new timeout req can have a small req->sequence.

2. cached_sq_head of now may overflow compare with before req. And it
will lead the timeout req with small req->sequence.

This overflow will lead to the misorder of timeout_list, which can lead
to the wrong order of the completion of timeout_list. Fix it by reuse
req->submit.sequence to store the count, and change the logic of
inserting sort in io_timeout.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-15 08:55:50 -06:00
Linus Torvalds
b27528b027 for-linus-20191012
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Merge tag 'for-linus-20191012' of git://git.kernel.dk/linux-block

Pull io_uring fix from Jens Axboe:
 "Single small fix for a regression in the sequence logic for linked
  commands"

* tag 'for-linus-20191012' of git://git.kernel.dk/linux-block:
  io_uring: fix sequence logic for timeout requests
2019-10-13 08:15:35 -07:00
Linus Torvalds
297cbcccc2 for-linus-20191010
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Merge tag 'for-linus-20191010' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - Fix wbt performance regression introduced with the blk-rq-qos
   refactoring (Harshad)

 - Fix io_uring fileset removal inadvertently killing the workqueue (me)

 - Fix io_uring typo in linked command nonblock submission (Pavel)

 - Remove spurious io_uring wakeups on request free (Pavel)

 - Fix null_blk zoned command error return (Keith)

 - Don't use freezable workqueues for backing_dev, also means we can
   revert a previous libata hack (Mika)

 - Fix nbd sysfs mutex dropped too soon at removal time (Xiubo)

* tag 'for-linus-20191010' of git://git.kernel.dk/linux-block:
  nbd: fix possible sysfs duplicate warning
  null_blk: Fix zoned command return code
  io_uring: only flush workqueues on fileset removal
  io_uring: remove wait loop spurious wakeups
  blk-wbt: fix performance regression in wbt scale_up/scale_down
  Revert "libata, freezer: avoid block device removal while system is frozen"
  bdi: Do not use freezable workqueue
  io_uring: fix reversed nonblock flag for link submission
2019-10-11 08:45:32 -07:00
Jens Axboe
7adf4eaf60 io_uring: fix sequence logic for timeout requests
We have two ways a request can be deferred:

1) It's a regular request that depends on another one
2) It's a timeout that tracks completions

We have a shared helper to determine whether to defer, and that
attempts to make the right decision based on the request. But we
only have some of this information in the caller. Un-share the
two timeout/defer helpers so the caller can use the right one.

Fixes: 5262f56798 ("io_uring: IORING_OP_TIMEOUT support")
Reported-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-10 21:42:58 -06:00
Jens Axboe
8a99734081 io_uring: only flush workqueues on fileset removal
We should not remove the workqueue, we just need to ensure that the
workqueues are synced. The workqueues are torn down on ctx removal.

Cc: stable@vger.kernel.org
Fixes: 6b06314c47 ("io_uring: add file set registration")
Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-09 15:13:47 -06:00
Pavel Begunkov
6805b32ec2 io_uring: remove wait loop spurious wakeups
Any changes interesting to tasks waiting in io_cqring_wait() are
commited with io_cqring_ev_posted(). However, io_ring_drop_ctx_refs()
also tries to do that but with no reason, that means spurious wakeups
every io_free_req() and io_uring_enter().

Just use percpu_ref_put() instead.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-07 21:16:24 -06:00
Linus Torvalds
c4bd70e8c9 for-linus-2019-10-03
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Merge tag 'for-linus-2019-10-03' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - Mandate timespec64 for the io_uring timeout ABI (Arnd)

 - Set of NVMe changes via Sagi:
     - controller removal race fix from Balbir
     - quirk additions from Gabriel and Jian-Hong
     - nvme-pci power state save fix from Mario
     - Add 64bit user commands (for 64bit registers) from Marta
     - nvme-rdma/nvme-tcp fixes from Max, Mark and Me
     - Minor cleanups and nits from James, Dan and John

 - Two s390 dasd fixes (Jan, Stefan)

 - Have loop change block size in DIO mode (Martijn)

 - paride pg header ifdef guard (Masahiro)

 - Two blk-mq queue scheduler tweaks, fixing an ordering issue on zoned
   devices and suboptimal performance on others (Ming)

* tag 'for-linus-2019-10-03' of git://git.kernel.dk/linux-block: (22 commits)
  block: sed-opal: fix sparse warning: convert __be64 data
  block: sed-opal: fix sparse warning: obsolete array init.
  block: pg: add header include guard
  Revert "s390/dasd: Add discard support for ESE volumes"
  s390/dasd: Fix error handling during online processing
  io_uring: use __kernel_timespec in timeout ABI
  loop: change queue block size to match when using DIO
  blk-mq: apply normal plugging for HDD
  blk-mq: honor IO scheduler for multiqueue devices
  nvme-rdma: fix possible use-after-free in connect timeout
  nvme: Move ctrl sqsize to generic space
  nvme: Add ctrl attributes for queue_count and sqsize
  nvme: allow 64-bit results in passthru commands
  nvme: Add quirk for Kingston NVME SSD running FW E8FK11.T
  nvmet-tcp: remove superflous check on request sgl
  Added QUIRKs for ADATA XPG SX8200 Pro 512GB
  nvme-rdma: Fix max_hw_sectors calculation
  nvme: fix an error code in nvme_init_subsystem()
  nvme-pci: Save PCI state before putting drive into deepest state
  nvme-tcp: fix wrong stop condition in io_work
  ...
2019-10-04 09:56:51 -07:00
Pavel Begunkov
bf7ec93c64 io_uring: fix reversed nonblock flag for link submission
io_queue_link_head() accepts @force_nonblock flag, but io_ring_submit()
passes something opposite.

Fixes: c576666863 ("io_uring: optimize submit_and_wait API")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-04 08:31:15 -06:00
Arnd Bergmann
bdf2007311 io_uring: use __kernel_timespec in timeout ABI
All system calls use struct __kernel_timespec instead of the old struct
timespec, but this one was just added with the old-style ABI. Change it
now to enforce the use of __kernel_timespec, avoiding ABI confusion and
the need for compat handlers on 32-bit architectures.

Any user space caller will have to use __kernel_timespec now, but this
is unambiguous and works for any C library regardless of the time_t
definition. A nicer way to specify the timeout would have been a less
ambiguous 64-bit nanosecond value, but I suppose it's too late now to
change that as this would impact both 32-bit and 64-bit users.

Fixes: 5262f56798 ("io_uring: IORING_OP_TIMEOUT support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-01 09:53:29 -06:00
Linus Torvalds
738f531d87 for-5.4/io_uring-2019-09-27
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Merge tag 'for-5.4/io_uring-2019-09-27' of git://git.kernel.dk/linux-block

Pull more io_uring updates from Jens Axboe:
 "Just two things in here:

   - Improvement to the io_uring CQ ring wakeup for batched IO (me)

   - Fix wrong comparison in poll handling (yangerkun)

  I realize the first one is a little late in the game, but it felt
  pointless to hold it off until the next release. Went through various
  testing and reviews with Pavel and peterz"

* tag 'for-5.4/io_uring-2019-09-27' of git://git.kernel.dk/linux-block:
  io_uring: make CQ ring wakeups be more efficient
  io_uring: compare cached_cq_tail with cq.head in_io_uring_poll
2019-09-27 12:08:24 -07:00
Jens Axboe
bda521624e io_uring: make CQ ring wakeups be more efficient
For batched IO, it's not uncommon for waiters to ask for more than 1
IO to complete before being woken up. This is a problem with
wait_event() since tasks will get woken for every IO that completes,
re-check condition, then go back to sleep. For batch counts on the
order of what you do for high IOPS, that can result in 10s of extra
wakeups for the waiting task.

Add a private wake function that checks for the wake up count criteria
being met before calling autoremove_wake_function(). Pavel reports that
one test case he has runs 40% faster with proper batching of wakeups.

Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-26 03:55:40 -06:00
Linus Torvalds
b6cb84b4fc for-5.4/io_uring-2019-09-24
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Merge tag 'for-5.4/io_uring-2019-09-24' of git://git.kernel.dk/linux-block

Pull more io_uring updates from Jens Axboe:
 "A collection of later fixes and additions, that weren't quite ready
  for pushing out with the initial pull request.

  This contains:

   - Fix potential use-after-free of shadow requests (Jackie)

   - Fix potential OOM crash in request allocation (Jackie)

   - kmalloc+memcpy -> kmemdup cleanup (Jackie)

   - Fix poll crash regression (me)

   - Fix SQ thread not being nice and giving up CPU for !PREEMPT (me)

   - Add support for timeouts, making it easier to do epoll_wait()
     conversions, for instance (me)

   - Ensure io_uring works without f_ops->read_iter() and
     f_ops->write_iter() (me)"

* tag 'for-5.4/io_uring-2019-09-24' of git://git.kernel.dk/linux-block:
  io_uring: correctly handle non ->{read,write}_iter() file_operations
  io_uring: IORING_OP_TIMEOUT support
  io_uring: use cond_resched() in sqthread
  io_uring: fix potential crash issue due to io_get_req failure
  io_uring: ensure poll commands clear ->sqe
  io_uring: fix use-after-free of shadow_req
  io_uring: use kmemdup instead of kmalloc and memcpy
2019-09-24 16:40:21 -07:00
Matthew Wilcox (Oracle)
a50b854e07 mm: introduce page_size()
Patch series "Make working with compound pages easier", v2.

These three patches add three helpers and convert the appropriate
places to use them.

This patch (of 3):

It's unnecessarily hard to find out the size of a potentially huge page.
Replace 'PAGE_SIZE << compound_order(page)' with page_size(page).

Link: http://lkml.kernel.org/r/20190721104612.19120-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-24 15:54:08 -07:00
yangerkun
daa5de5415 io_uring: compare cached_cq_tail with cq.head in_io_uring_poll
After 75b28af("io_uring: allocate the two rings together"), we compare
sq.head with cached_cq_tail to determine does there any cq invalid.
Actually, we should use cq.head.

Fixes: 75b28affdd ("io_uring: allocate the two rings together")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-24 07:04:15 -06:00
Jens Axboe
32960613b7 io_uring: correctly handle non ->{read,write}_iter() file_operations
Currently we just -EINVAL a read or write to an fd that isn't backed
by ->read_iter() or ->write_iter(). But we can handle them just fine,
as long as we punt fo async context first.

Implement a simple loop function for doing ->read() or ->write()
instead, and ensure we call it appropriately.

Reported-by: 李通洲 <carter.li@eoitek.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-23 11:05:34 -06:00
Jens Axboe
5262f56798 io_uring: IORING_OP_TIMEOUT support
There's been a few requests for functionality similar to io_getevents()
and epoll_wait(), where the user can specify a timeout for waiting on
events. I deliberately did not add support for this through the system
call initially to avoid overloading the args, but I can see that the use
cases for this are valid.

This adds support for IORING_OP_TIMEOUT. If a user wants to get woken
when waiting for events, simply submit one of these timeout commands
with your wait call (or before). This ensures that the application
sleeping on the CQ ring waiting for events will get woken. The timeout
command is passed in as a pointer to a struct timespec. Timeouts are
relative. The timeout command also includes a way to auto-cancel after
N events has passed.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-18 10:43:22 -06:00
Jens Axboe
9831a90ce6 io_uring: use cond_resched() in sqthread
If preempt isn't enabled in the kernel, we can run into hang issues with
sqthread submissions. Use cond_resched() to play nice instead of
cpu_relax(), if we end up starting the loop and not having any events
pending for submissions.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-19 09:49:26 -06:00
Jackie Liu
a1041c27b6 io_uring: fix potential crash issue due to io_get_req failure
Sometimes io_get_req will return a NUL, then we need to do the
correct error handling, otherwise it will cause the kernel null
pointer exception.

Fixes: 4fe2c96315 ("io_uring: add support for link with drain")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-18 11:20:04 -06:00
Jens Axboe
6cc47d1d2a io_uring: ensure poll commands clear ->sqe
If we end up getting woken in poll (due to a signal), then we may need
to punt the poll request to an async worker. When we do that, we look up
the list to queue at, deferefencing req->submit.sqe, however that is
only set for requests we initially decided to queue async.

This fixes a crash with poll command usage and wakeups that need to punt
to async context.

Fixes: 54a91f3bb9 ("io_uring: limit parallelism of buffered writes")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-18 11:19:26 -06:00
Jackie Liu
5f5ad9ced3 io_uring: fix use-after-free of shadow_req
There is a potential dangling pointer problem. we never clean
shadow_req, if there are multiple link lists in this series of
sqes, then the shadow_req will not reallocate, and continue to
use the last one. but in the previous, his memory has been
released, thus forming a dangling pointer. let's clean up him
and make sure that every new link list can reapply for a new
shadow_req.

Fixes: 4fe2c96315 ("io_uring: add support for link with drain")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-18 11:19:06 -06:00
Jackie Liu
954dab193d io_uring: use kmemdup instead of kmalloc and memcpy
Just clean up the code, no function changes.

Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-18 11:19:06 -06:00
Daniel Xu
5277deaab9 io_uring: increase IORING_MAX_ENTRIES to 32K
Some workloads can require far more than 4K oustanding entries. For
example memcached can have ~300K sockets over ~40 cores. Bumping the max
to 32K seems to work pretty well.

Reported-by: Dan Melnic <dmm@fb.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-14 17:06:22 -06:00
Jens Axboe
b2a9eadab8 io_uring: make sqpoll wakeup possible with getevents
The way the logic is setup in io_uring_enter() means that you can't wake
up the SQ poller thread while at the same time waiting (or polling) for
completions afterwards. There's no reason for that to be the case.

Reported-by: Lewis Baker <lbaker@fb.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-12 14:19:16 -06:00
Jens Axboe
6d5d5ac522 io_uring: extend async work merging
We currently merge async work items if we see a strict sequential hit.
This helps avoid unnecessary workqueue switches when we don't need
them. We can extend this merging to cover cases where it's not a strict
sequential hit, but the IO still fits within the same page. If an
application is doing multiple requests within the same page, we don't
want separate workers waiting on the same page to complete IO. It's much
faster to let the first worker bring in the page, then operate on that
page from the same worker to complete the next request(s).

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-12 14:18:48 -06:00
Jens Axboe
54a91f3bb9 io_uring: limit parallelism of buffered writes
All the popular filesystems need to grab the inode lock for buffered
writes. With io_uring punting buffered writes to async context, we
observe a lot of contention with all workers hamming this mutex.

For buffered writes, we generally don't need a lot of parallelism on
the submission side, as the flushing will take care of that for us.
Hence we don't need a deep queue on the write side, as long as we
can safely punt from the original submission context.

Add a workqueue with a limit of 2 that we can use for buffered writes.
This greatly improves the performance and efficiency of higher queue
depth buffered async writes with io_uring.

Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-10 09:49:35 -06:00
Jens Axboe
18d9be1a97 io_uring: add io_queue_async_work() helper
Add a helper for queueing a request for async execution, in preparation
for optimizing it.

No functional change in this patch.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-10 09:13:05 -06:00
Jens Axboe
c576666863 io_uring: optimize submit_and_wait API
For some applications that end up using a submit-and-wait type of
approach for certain batches of IO, we can make that a bit more
efficient by allowing the application to block for the last IO
submission. This prevents an async when we don't need it, as the
application will be blocking for the completion event(s) anyway.

Typical use cases are using the liburing
io_uring_submit_and_wait() API, or just using io_uring_enter()
doing both submissions and completions. As a specific example,
RocksDB doing MultiGet() is sped up quite a bit with this
change.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-10 08:21:03 -06:00
Jackie Liu
4fe2c96315 io_uring: add support for link with drain
To support the link with drain, we need to do two parts.

There is an sqes:

    0     1     2     3     4     5     6
 +-----+-----+-----+-----+-----+-----+-----+
 |  N  |  L  |  L  | L+D |  N  |  N  |  N  |
 +-----+-----+-----+-----+-----+-----+-----+

First, we need to ensure that the io before the link is completed,
there is a easy way is set drain flag to the link list's head, so
all subsequent io will be inserted into the defer_list.

	+-----+
    (0) |  N  |
	+-----+
           |          (2)         (3)         (4)
	+-----+     +-----+     +-----+     +-----+
    (1) | L+D | --> |  L  | --> | L+D | --> |  N  |
	+-----+     +-----+     +-----+     +-----+
           |
	+-----+
    (5) |  N  |
	+-----+
           |
	+-----+
    (6) |  N  |
	+-----+

Second, ensure that the following IO will not be completed first,
an easy way is to create a mirror of drain io and insert it into
defer_list, in this way, as long as drain io is not processed, the
following io in the defer_list will not be actively process.

	+-----+
    (0) |  N  |
	+-----+
           |          (2)         (3)         (4)
	+-----+     +-----+     +-----+     +-----+
    (1) | L+D | --> |  L  | --> | L+D | --> |  N  |
	+-----+     +-----+     +-----+     +-----+
           |
	+-----+
   ('3) |  D  |   <== This is a shadow of (3)
	+-----+
           |
	+-----+
    (5) |  N  |
	+-----+
           |
	+-----+
    (6) |  N  |
	+-----+

Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-09 16:15:00 -06:00
Jackie Liu
8776f3fa15 io_uring: fix wrong sequence setting logic
Sqo_thread will get sqring in batches, which will cause
ctx->cached_sq_head to be added in batches. if one of these
sqes is set with the DRAIN flag, then he will never get a
chance to process, and finally sqo_thread will not exit.

Fixes: de0617e467 ("io_uring: add support for marking commands as draining")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-09 16:14:47 -06:00
Jens Axboe
ac90f249e1 io_uring: expose single mmap capability
After commit 75b28affdd we can get by with just a single mmap to
map both the sq and cq ring. However, userspace doesn't know that.

Add a features variable to io_uring_params, and notify userspace
that the kernel has this ability. This can then be used in liburing
(or in applications directly) to avoid the second mmap.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-06 10:26:21 -06:00
Hristo Venev
75b28affdd io_uring: allocate the two rings together
Both the sq and the cq rings have sizes just over a power of two, and
the sq ring is significantly smaller. By bundling them in a single
alllocation, we get the sq ring for free.

This also means that IORING_OFF_SQ_RING and IORING_OFF_CQ_RING now mean
the same thing. If we indicate this to userspace, we can save a mmap
call.

Signed-off-by: Hristo Venev <hristo@venev.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27 10:42:02 -06:00
John Hubbard
27c4d3a325 fs/io_uring.c: convert put_page() to put_user_page*()
For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca
("mm: introduce put_user_page*(), placeholder versions").

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-block@vger.kernel.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27 10:41:41 -06:00
Jens Axboe
08f5439f1d io_uring: add need_resched() check in inner poll loop
The outer poll loop checks for whether we need to reschedule, and
returns to userspace if we do. However, it's possible to get stuck
in the inner loop as well, if the CPU we are running on needs to
reschedule to finish the IO work.

Add the need_resched() check in the inner loop as well. This fixes
a potential hang if the kernel is configured with
CONFIG_PREEMPT_VOLUNTARY=y.

Reported-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-22 15:32:28 -06:00