There are no more users of struct io_uring_cmd_data and its op_data
field. Remove it to shave 8 bytes from struct io_async_cmd and eliminate
a store and load for every uring_cmd.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20250708202212.2851548-5-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a flag IORING_URING_CMD_REISSUE that ->uring_cmd() implementations
can use to tell whether this is the first or subsequent issue of the
uring_cmd. This will allow ->uring_cmd() implementations to store
information in the io_uring_cmd's pdu across issues.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20250708202212.2851548-3-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a helper for posting 32 byte CQEs in a multishot mode and add a cmd
helper on top. As it specifically works with requests, the helper ignore
the passed in cqe->user_data and sets it to the one stored in the
request.
The command helper is only valid with multishot requests.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c29d7720c16e1f981cfaa903df187138baa3946b.1750065793.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Some commands like timestamping in the next patch can make use of
multishot polling, i.e. REQ_F_APOLL_MULTISHOT. Add support for that,
which is condensed in a single helper called io_cmd_poll_multishot().
The user who wants to continue with a request in a multishot mode must
call the function, and only if it returns 0 the user is free to proceed.
Apart from normal terminal errors, it can also end up with -EIOCBQUEUED,
in which case the user must forward it to the core io_uring. It's
forbidden to use task work while the request is executing in a multishot
mode.
The API is not foolproof, hence it's not exported to modules nor exposed
in public headers.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bcf97c31659662c72b69fc8fcdf2a88cfc16e430.1750065793.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
uring_cmd currently copies the full SQE at prep time, just in case it
needs it to be stable. However, for inline completions or requests that
get queued up on the device side, there's no need to ever copy the SQE.
This is particularly important, as various use cases of uring_cmd will
be using 128b sized SQEs.
Opt in to using ->sqe_copy() to let the core of io_uring decide when to
copy SQEs. This callback will only be called if it is safe to do so.
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For IORING_URING_CMD_FIXED-less commands io_uring doesn't pull buf_index
from the sqe, so imports might succeed if the index coincide, e.g. when
it's 0, but otherwise it's error prone. Warn if someone tries to import
without the flag.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Link: https://lore.kernel.org/r/a1c2c88e53c3fe96978f23d50c6bc66c2c79c337.1747991070.git.asml.silence@gmail.com
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>
Merge in 6.15 io_uring fixes, mostly so that the fdinfo changes can
get easily extended without causing merge conflicts.
* io_uring-6.15:
io_uring/fdinfo: grab ctx->uring_lock around io_uring_show_fdinfo()
io_uring/memmap: don't use page_address() on a highmem page
io_uring/uring_cmd: fix hybrid polling initialization issue
io_uring/sqpoll: Increase task_work submission batch size
io_uring: ensure deferred completions are flushed for multishot
io_uring: always arm linked timeouts prior to issue
io_uring/fdinfo: annotate racy sq/cq head/tail reads
io_uring: fix 'sync' handling of io_fallback_tw()
io_uring: don't duplicate flushing in io_req_post_cqe
Modify the check for whether the timer is initialized during IO transfer
when passthrough is used with hybrid polling, to ensure that it's always
setup correctly.
Cc: stable@vger.kernel.org
Fixes: 01ee194d1a ("io_uring: add support for hybrid IOPOLL")
Signed-off-by: hexue <xue01.he@samsung.com>
Link: https://lore.kernel.org/r/20250512052025.293031-1-xue01.he@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring_cmd_import_fixed_vec() is a cmd helper around vectored
registered buffer import functions, which caches the memory under
the hood. The lifetime of the vectore and hence the iterator is bound to
the request. Furthermore, the user is not allowed to call it multiple
times for a single request.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/97487a80dec3fb8cf8aeedf1f9026ef6d503fe4b.1742579999.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add iou_vec to commands and wire caching for it, but don't expose it to
users just yet. We need the vec cleared on initial alloc, but since
we can't place it at the beginning at the moment, zero the entire
async_data. It's cached, and the performance effects only the initial
allocation, and it might be not a bad idea since we're exposing those
bits to outside drivers.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c0f2145b75791bc6106eb4e72add2cf6a2c72a7a.1742579999.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring needs private bits in cmd's ->async_data, and they should never
be exposed to drivers as it'd certainly be abused. Leave struct
io_uring_cmd_data for the drivers but wrap it into a structure. It's a
prep patch and doesn't do anything useful yet.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20250319061251.21452-3-sidong.yang@furiosa.ai
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring_cmd_import_fixed() takes a struct io_uring_cmd *, but the type
of the ioucmd parameter is void *. Make the pointer type explicit so the
compiler can type check it.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://lore.kernel.org/r/20250228221514.604350-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Registered buffer are currently imported in two steps, first we lookup
a rsrc node and then use it to set up the iterator. The first part is
usually done at the prep stage, and import happens whenever it's needed.
As we want to defer binding to a node so that it works with linked
requests, combine both steps into a single helper.
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250224213116.3509093-6-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring_cmd_import_fixed() will need to know the io_uring execution
state in following commits, for now just pass issue_flags into it
without actually using.
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250224213116.3509093-5-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for changing how io_tw_state is passed, introduce a type
alias io_tw_token_t for struct io_tw_state *. This allows for changing
the representation in one place, without having to update the many
functions that just forward their struct io_tw_state * argument.
Also add a comment to struct io_tw_state to explain its purpose.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://lore.kernel.org/r/20250217022511.1150145-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This isn't generally necessary, but conditions have been observed where
SQE data is accessed from the original SQE after prep has been done and
outside of the initial issue. Opcode prep handlers must ensure that any
SQE related data is stable beyond the prep phase, but uring_cmd is a bit
special in how it handles the SQE which makes it susceptible to reading
stale data. If the application has reused the SQE before the original
completes, then that can lead to data corruption.
Down the line we can relax this again once uring_cmd has been sanitized
a bit, and avoid unnecessarily copying the SQE.
Fixes: 5eff57fa9f ("io_uring/uring_cmd: defer SQE copying until it's needed")
Reported-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Any uring_cmd always has async data allocated now, there's no reason to
check and clear a cached copy of the SQE.
Fixes: d10f19dff5 ("io_uring/uring_cmd: switch to always allocating async data")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
5eff57fa9f ("io_uring/uring_cmd: defer SQE copying until it's needed")
moved the unconditional memcpy() of the uring_cmd SQE to async_data
to 2 cases when the request goes async:
- If REQ_F_FORCE_ASYNC is set to force the initial issue to go async
- If ->uring_cmd() returns -EAGAIN in the initial non-blocking issue
Unlike the REQ_F_FORCE_ASYNC case, in the EAGAIN case, io_uring_cmd()
copies the SQE to async_data but neglects to update the io_uring_cmd's
sqe field to point to async_data. As a result, sqe still points to the
slot in the userspace-mapped SQ. At the end of io_submit_sqes(), the
kernel advances the SQ head index, allowing userspace to reuse the slot
for a new SQE. If userspace reuses the slot before the io_uring worker
reissues the original SQE, the io_uring_cmd's SQE will be corrupted.
Introduce a helper io_uring_cmd_cache_sqes() to copy the original SQE to
the io_uring_cmd's async_data and point sqe there. Use it for both the
REQ_F_FORCE_ASYNC and EAGAIN cases. This ensures the uring_cmd doesn't
read from the SQ slot after it has been returned to userspace.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 5eff57fa9f ("io_uring/uring_cmd: defer SQE copying until it's needed")
Link: https://lore.kernel.org/r/20250212204546.3751645-3-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
eaf72f7b41 ("io_uring/uring_cmd: cleanup struct io_uring_cmd_data
layout") removed most of the places assuming struct io_uring_cmd_data
has sqes as its first field. However, the EAGAIN case in io_uring_cmd()
still compares ioucmd->sqe to the struct io_uring_cmd_data pointer using
a void * cast. Since fa3595523d ("io_uring: get rid of alloc cache
init_once handling"), sqes is no longer io_uring_cmd_data's first field.
As a result, the pointers will always compare unequal and memcpy() may
be called with the same source and destination.
Replace the incorrect void * cast with the address of the sqes field.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: eaf72f7b41 ("io_uring/uring_cmd: cleanup struct io_uring_cmd_data layout")
Link: https://lore.kernel.org/r/20250212204546.3751645-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
init_once is called when an object doesn't come from the cache, and
hence needs initial clearing of certain members. While the whole
struct could get cleared by memset() in that case, a few of the cache
members are large enough that this may cause unnecessary overhead if
the caches used aren't large enough to satisfy the workload. For those
cases, some churn of kmalloc+kfree is to be expected.
Ensure that the 3 users that need clearing put the members they need
cleared at the start of the struct, and wrap the rest of the struct in
a struct group so the offset is known.
While at it, improve the interaction with KASAN such that when/if
KASAN writes to members inside the struct that should be retained over
caching, it won't trip over itself. For rw and net, the retaining of
the iovec over caching is disabled if KASAN is enabled. A helper will
free and clear those members in that case.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A few spots in uring_cmd assume that the SQEs copied are always at the
start of the structure, and hence mix req->async_data and the struct
itself.
Clean that up and use the proper indices.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring_cmd_sock() does a normal read of cmd->sqe->cmd_op, where it
really should be using a READ_ONCE() as ->sqe may still be pointing to
the original SQE. Since the prep side already does this READ_ONCE() and
stores it locally, use that value rather than re-read it.
Fixes: 8e9fad0e70 ("io_uring: Add io_uring command support for sockets")
Link: https://lore.kernel.org/r/20250121-uring-sockcmd-fix-v1-1-add742802a29@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.14/io_uring-20250119' of git://git.kernel.dk/linux
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
...
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Merge tag 'for-6.13-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes.
Besides the one-liners in Btrfs there's fix to the io_uring and
encoded read integration (added in this development cycle). The update
to io_uring provides more space for the ongoing command that is then
used in Btrfs to handle some cases.
- io_uring and encoded read:
- provide stable storage for io_uring command data
- make a copy of encoded read ioctl call, reuse that in case the
call would block and will be called again
- properly initialize zlib context for hardware compression on s390
- fix max extent size calculation on filesystems with non-zoned
devices
- fix crash in scrub on crafted image due to invalid extent tree"
* tag 'for-6.13-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: zlib: fix avail_in bytes for s390 zlib HW compression path
btrfs: zoned: calculate max_extent_size properly on non-zoned setup
btrfs: avoid NULL pointer dereference if no valid extent tree
btrfs: don't read from userspace twice in btrfs_uring_encoded_read()
io_uring: add io_uring_cmd_get_async_data helper
io_uring/cmd: add per-op data to struct io_uring_cmd_data
io_uring/cmd: rename struct uring_cache to io_uring_cmd_data
In case an op handler for ->uring_cmd() needs stable storage for user
data, it can allocate io_uring_cmd_data->op_data and use it for the
duration of the request. When the request gets cleaned up, uring_cmd
will free it automatically.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: David Sterba <dsterba@suse.com>
In preparation for making this more generically available for
->uring_cmd() usage that needs stable command data, rename it and move
it to io_uring/cmd.h instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: David Sterba <dsterba@suse.com>
Change the type of the res2 parameter in io_uring_cmd_done from ssize_t
to u64. This aligns the parameter type with io_req_set_cqe32_extra,
which expects u64 arguments.
The change eliminates potential issues on 32-bit architectures where
ssize_t might be 32-bit.
Only user of passing res2 is drivers/nvme/host/ioctl.c and it actually
passes u64.
Fixes: ee692a21e9 ("fs,io_uring: add infrastructure for uring-cmd")
Cc: stable@vger.kernel.org
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Tested-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
Link: https://lore.kernel.org/r/20241203-io_uring_cmd_done-res2-as-u64-v2-1-5e59ae617151@ddn.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-6.13/io_uring-20241118' of git://git.kernel.dk/linux
Pull io_uring updates from Jens Axboe:
- Cleanups of the eventfd handling code, making it fully private.
- Support for sending a sync message to another ring, without having a
ring available to send a normal async message.
- Get rid of the separate unlocked hash table, unify everything around
the single locked one.
- Add support for ring resizing. It can be hard to appropriately size
the CQ ring upfront, if the application doesn't know how busy it will
be. This results in applications sizing rings for the most busy case,
which can be wasteful. With ring resizing, they can start small and
grow the ring, if needed.
- Add support for fixed wait regions, rather than needing to copy the
same wait data tons of times for each wait operation.
- Rewrite the resource node handling, which before was serialized per
ring. This caused issues with particularly fixed files, where one
file waiting on IO could hold up putting and freeing of other
unrelated files. Now each node is handled separately. New code is
much simpler too, and was a net 250 line reduction in code.
- Add support for just doing partial buffer clones, rather than always
cloning the entire buffer table.
- Series adding static NAPI support, where a specific NAPI instance is
used rather than having a list of them available that need lookup.
- Add support for mapped regions, and also convert the fixed wait
support mentioned above to that concept. This avoids doing special
mappings for various planned features, and folds the existing
registered wait into that too.
- Add support for hybrid IO polling, which is a variant of strict
IOPOLL but with an initial sleep delay to avoid spinning too early
and wasting resources on devices that aren't necessarily in the < 5
usec category wrt latencies.
- Various cleanups and little fixes.
* tag 'for-6.13/io_uring-20241118' of git://git.kernel.dk/linux: (79 commits)
io_uring/region: fix error codes after failed vmap
io_uring: restore back registered wait arguments
io_uring: add memory region registration
io_uring: introduce concept of memory regions
io_uring: temporarily disable registered waits
io_uring: disable ENTER_EXT_ARG_REG for IOPOLL
io_uring: fortify io_pin_pages with a warning
switch io_msg_ring() to CLASS(fd)
io_uring: fix invalid hybrid polling ctx leaks
io_uring/uring_cmd: fix buffer index retrieval
io_uring/rsrc: add & apply io_req_assign_buf_node()
io_uring/rsrc: remove '->ctx_ptr' of 'struct io_rsrc_node'
io_uring/rsrc: pass 'struct io_ring_ctx' reference to rsrc helpers
io_uring: avoid normal tw intermediate fallback
io_uring/napi: add static napi tracking strategy
io_uring/napi: clean up __io_napi_do_busy_loop
io_uring/napi: Use lock guards
io_uring/napi: improve __io_napi_add
io_uring/napi: fix io_napi_entry RCU accesses
io_uring/napi: protect concurrent io_napi_entry timeout accesses
...
When the taks that submitted a request is dying, a task work for that
request might get run by a kernel thread or even worse by a half
dismantled task. We can't just cancel the task work without running the
callback as the cmd might need to do some clean up, so pass a flag
instead. If set, it's not safe to access any task resources and the
callback is expected to cancel the cmd ASAP.
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The following pattern becomes more and more:
+ io_req_assign_rsrc_node(&req->buf_node, node);
+ req->flags |= REQ_F_BUF_NODE;
so make it a helper, which is less fragile to use than above code, for
example, the BUF_NODE flag is even missed in current io_uring_cmd_prep().
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241107110149.890530-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than store the task_struct itself in struct io_kiocb, store
the io_uring specific task_struct. The life times are the same in terms
of io_uring, and this avoids doing some dereferences through the
task_struct. For the hot path of putting local task references, we can
deref req->tctx instead, which we'll need anyway in that function
regardless of whether it's local or remote references.
This is mostly straight forward, except the original task PF_EXITING
check needs a bit of tweaking. task_work is _always_ run from the
originating task, except in the fallback case, where it's run from a
kernel thread. Replace the potentially racy (in case of fallback work)
checks for req->task->flags with current->flags. It's either the still
the original task, in which case PF_EXITING will be sane, or it has
PF_KTHREAD set, in which case it's fallback work. Both cases should
prevent moving forward with the given request.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Right now the task_struct pointer is used as the key to match a task,
but in preparation for some io_kiocb changes, move it to using struct
io_uring_task instead. No functional changes intended in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently the io_rsrc_node assignment in io_kiocb is an array of two
pointers, as two nodes may be assigned to a request - one file node,
and one buffer node. However, the buffer node can co-exist with the
provided buffers, as currently it's not supported to use both provided
and registered buffers at the same time.
This crucially brings struct io_kiocb down to 4 cache lines again, as
before it spilled into the 5th cacheline.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There are lots of spots open-coding this functionality, add a generic
helper that does the node lookup in a speculation safe way.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For files, there's nr_user_files/file_table/file_data, and buffers have
nr_user_bufs/user_bufs/buf_data. There's no reason why file_table and
file_data can't be the same thing, and ditto for the buffer side. That
gets rid of more io_ring_ctx state that's in two spots rather than just
being in one spot, as it should be. Put all the registered file data in
one locations, and ditto on the buffer front.
This also avoids having both io_rsrc_data->nodes being an allocated
array, and ->user_bufs[] or ->file_table.nodes. There's no reason to
have this information duplicated. Keep it in one spot, io_rsrc_data,
along with how many resources are available.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Work in progress, but get rid of the per-ring serialization of resource
nodes, like registered buffers and files. Main issue here is that one
node can otherwise hold up a bunch of other nodes from getting freed,
which is especially a problem for file resource nodes and networked
workloads where some descriptors may not see activity in a long time.
As an example, instantiate an io_uring ring fd and create a sparse
registered file table. Even 2 will do. Then create a socket and register
it as fixed file 0, F0. The number of open files in the app is now 5,
with 0/1/2 being the usual stdin/out/err, 3 being the ring fd, and 4
being the socket. Register this socket (eg "the listener") in slot 0 of
the registered file table. Now add an operation on the socket that uses
slot 0. Finally, loop N times, where each loop creates a new socket,
registers said socket as a file, then unregisters the socket, and
finally closes the socket. This is roughly similar to what a basic
accept loop would look like.
At the end of this loop, it's not unreasonable to expect that there
would still be 5 open files. Each socket created and registered in the
loop is also unregistered and closed. But since the listener socket
registered first still has references to its resource node due to still
being active, each subsequent socket unregistration is stuck behind it
for reclaim. Hence 5 + N files are still open at that point, where N is
awaiting the final put held up by the listener socket.
Rewrite the io_rsrc_node handling to NOT rely on serialization. Struct
io_kiocb now gets explicit resource nodes assigned, with each holding a
reference to the parent node. A parent node is either of type FILE or
BUFFER, which are the two types of nodes that exist. A request can have
two nodes assigned, if it's using both registered files and buffers.
Since request issue and task_work completion is both under the ring
private lock, no atomics are needed to handle these references. It's a
simple unlocked inc/dec. As before, the registered buffer or file table
each hold a reference as well to the registered nodes. Final put of the
node will remove the node and free the underlying resource, eg unmap the
buffer or put the file.
Outside of removing the stall in resource reclaim described above, it
has the following advantages:
1) It's a lot simpler than the previous scheme, and easier to follow.
No need to specific quiesce handling anymore.
2) There are no resource node allocations in the fast path, all of that
happens at resource registration time.
3) The structs related to resource handling can all get simplified
quite a bit, like io_rsrc_node and io_rsrc_data. io_rsrc_put can
go away completely.
4) Handling of resource tags is much simpler, and doesn't require
persistent storage as it can simply get assigned up front at
registration time. Just copy them in one-by-one at registration time
and assign to the resource node.
The only real downside is that a request is now explicitly limited to
pinning 2 resources, one file and one buffer, where before just
assigning a resource node to a request would pin all of them. The upside
is that it's easier to follow now, as an individual resource is
explicitly referenced and assigned to the request.
With this in place, the above mentioned example will be using exactly 5
files at the end of the loop, not N.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All callers already hold the ring lock and hence are passing '0',
remove the argument and the conditional locking that it controlled.
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's pretty pointless to use io_kiocb as intermediate storage for this,
so split the validity check and the actual usage. The resource node is
assigned upfront at prep time, to prevent it from going away. The actual
import is never called with the ctx->uring_lock held, so grab it for
the import.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When an io_uring request needs blocking context we offload it to the
io_uring's thread pool called io-wq. We can get there off ->uring_cmd
by returning -EAGAIN, but there is no straightforward way of doing that
from an asynchronous callback. Add a helper that would transfer a
command to a blocking context.
Note, we do an extra hop via task_work before io_queue_iowq(), that's a
limitation of io_uring infra we have that can likely be lifted later
if that would ever become a problem.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f735f807d7c8ba50c9452c69dfe5d3e9e535037b.1726072086.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We don't have to return error code from an op handler back to core
io_uring, so once io_uring_cmd() sets the results and handles errors we
can juts return IOU_OK and simplify the code.
Note, only valid with e0b23d9953 ("io_uring: optimise ltimeout for
inline execution"), there was a problem with iopoll before.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8eae2be5b2a49236cd5f1dadbd1aa5730e9e2d4f.1721819383.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
