It's a pointer, don't use 0 for that. sparse throws a warning for that,
as the kernel test robot noticed.
Fixes: 8cf0c45999 ("io_uring/rw: Allocate async data through helper")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202412180253.YML3qN4d-lkp@intel.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous commit changed overwriting kiocb->ki_flags with
->f_iocb_flags with masking it in. This breaks for retry situations,
where we don't necessarily want to retain previously set flags, like
IOCB_NOWAIT.
The use case needs IOCB_HAS_METADATA to be persistent, but the change
makes all flags persistent, which is an issue. Add a request flag to
track whether the request has metadata or not, as that is persistent
across issues.
Fixes: 4dde0cc445 ("io_uring: introduce attributes for read/write and PI support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove unnecessary call to iov_iter_save_state() in io_prep_rw_setup()
as io_import_iovec() already does this. Then the result from
io_import_iovec() can be returned directly.
Signed-off-by: David Wei <dw@davidwei.uk>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Tested-by: Li Zetao <lizetao1@huawei.com>
Link: https://lore.kernel.org/r/20241207004144.783631-1-dw@davidwei.uk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add the ability to pass additional attributes along with read/write.
Application can prepare attibute specific information and pass its
address using the SQE field:
__u64 attr_ptr;
Along with setting a mask indicating attributes being passed:
__u64 attr_type_mask;
Overall 64 attributes are allowed and currently one attribute
'IORING_RW_ATTR_FLAG_PI' is supported.
With PI attribute, userspace can pass following information:
- flags: integrity check flags IO_INTEGRITY_CHK_{GUARD/APPTAG/REFTAG}
- len: length of PI/metadata buffer
- addr: address of metadata buffer
- seed: seed value for reftag remapping
- app_tag: application defined 16b value
Process this information to prepare uio_meta_descriptor and pass it down
using kiocb->private.
PI attribute is supported only for direct IO.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20241128112240.8867-7-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
- The final step to get rid of auto-rearming posix-timers
posix-timers are currently auto-rearmed by the kernel when the signal
of the timer is ignored so that the timer signal can be delivered once
the corresponding signal is unignored.
This requires to throttle the timer to prevent a DoS by small intervals
and keeps the system pointlessly out of low power states for no value.
This is a long standing non-trivial problem due to the lock order of
posix-timer lock and the sighand lock along with life time issues as
the timer and the sigqueue have different life time rules.
Cure this by:
* Embedding the sigqueue into the timer struct to have the same life
time rules. Aside of that this also avoids the lookup of the timer
in the signal delivery and rearm path as it's just a always valid
container_of() now.
* Queuing ignored timer signals onto a seperate ignored list.
* Moving queued timer signals onto the ignored list when the signal is
switched to SIG_IGN before it could be delivered.
* Walking the ignored list when SIG_IGN is lifted and requeue the
signals to the actual signal lists. This allows the signal delivery
code to rearm the timer.
This also required to consolidate the signal delivery rules so they are
consistent across all situations. With that all self test scenarios
finally succeed.
- Core infrastructure for VFS multigrain timestamping
This is required to allow the kernel to use coarse grained time stamps
by default and switch to fine grained time stamps when inode attributes
are actively observed via getattr().
These changes have been provided to the VFS tree as well, so that the
VFS specific infrastructure could be built on top.
- Cleanup and consolidation of the sleep() infrastructure
* Move all sleep and timeout functions into one file
* Rework udelay() and ndelay() into proper documented inline functions
and replace the hardcoded magic numbers by proper defines.
* Rework the fsleep() implementation to take the reality of the timer
wheel granularity on different HZ values into account. Right now the
boundaries are hard coded time ranges which fail to provide the
requested accuracy on different HZ settings.
* Update documentation for all sleep/timeout related functions and fix
up stale documentation links all over the place
* Fixup a few usage sites
- Rework of timekeeping and adjtimex(2) to prepare for multiple PTP clocks
A system can have multiple PTP clocks which are participating in
seperate and independent PTP clock domains. So far the kernel only
considers the PTP clock which is based on CLOCK TAI relevant as that's
the clock which drives the timekeeping adjustments via the various user
space daemons through adjtimex(2).
The non TAI based clock domains are accessible via the file descriptor
based posix clocks, but their usability is very limited. They can't be
accessed fast as they always go all the way out to the hardware and
they cannot be utilized in the kernel itself.
As Time Sensitive Networking (TSN) gains traction it is required to
provide fast user and kernel space access to these clocks.
The approach taken is to utilize the timekeeping and adjtimex(2)
infrastructure to provide this access in a similar way how the kernel
provides access to clock MONOTONIC, REALTIME etc.
Instead of creating a duplicated infrastructure this rework converts
timekeeping and adjtimex(2) into generic functionality which operates
on pointers to data structures instead of using static variables.
This allows to provide time accessors and adjtimex(2) functionality for
the independent PTP clocks in a subsequent step.
- Consolidate hrtimer initialization
hrtimers are set up by initializing the data structure and then
seperately setting the callback function for historical reasons.
That's an extra unnecessary step and makes Rust support less straight
forward than it should be.
Provide a new set of hrtimer_setup*() functions and convert the core
code and a few usage sites of the less frequently used interfaces over.
The bulk of the htimer_init() to hrtimer_setup() conversion is already
prepared and scheduled for the next merge window.
- Drivers:
* Ensure that the global timekeeping clocksource is utilizing the
cluster 0 timer on MIPS multi-cluster systems.
Otherwise CPUs on different clusters use their cluster specific
clocksource which is not guaranteed to be synchronized with other
clusters.
* Mostly boring cleanups, fixes, improvements and code movement
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Merge tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"A rather large update for timekeeping and timers:
- The final step to get rid of auto-rearming posix-timers
posix-timers are currently auto-rearmed by the kernel when the
signal of the timer is ignored so that the timer signal can be
delivered once the corresponding signal is unignored.
This requires to throttle the timer to prevent a DoS by small
intervals and keeps the system pointlessly out of low power states
for no value. This is a long standing non-trivial problem due to
the lock order of posix-timer lock and the sighand lock along with
life time issues as the timer and the sigqueue have different life
time rules.
Cure this by:
- Embedding the sigqueue into the timer struct to have the same
life time rules. Aside of that this also avoids the lookup of
the timer in the signal delivery and rearm path as it's just a
always valid container_of() now.
- Queuing ignored timer signals onto a seperate ignored list.
- Moving queued timer signals onto the ignored list when the
signal is switched to SIG_IGN before it could be delivered.
- Walking the ignored list when SIG_IGN is lifted and requeue the
signals to the actual signal lists. This allows the signal
delivery code to rearm the timer.
This also required to consolidate the signal delivery rules so they
are consistent across all situations. With that all self test
scenarios finally succeed.
- Core infrastructure for VFS multigrain timestamping
This is required to allow the kernel to use coarse grained time
stamps by default and switch to fine grained time stamps when inode
attributes are actively observed via getattr().
These changes have been provided to the VFS tree as well, so that
the VFS specific infrastructure could be built on top.
- Cleanup and consolidation of the sleep() infrastructure
- Move all sleep and timeout functions into one file
- Rework udelay() and ndelay() into proper documented inline
functions and replace the hardcoded magic numbers by proper
defines.
- Rework the fsleep() implementation to take the reality of the
timer wheel granularity on different HZ values into account.
Right now the boundaries are hard coded time ranges which fail
to provide the requested accuracy on different HZ settings.
- Update documentation for all sleep/timeout related functions
and fix up stale documentation links all over the place
- Fixup a few usage sites
- Rework of timekeeping and adjtimex(2) to prepare for multiple PTP
clocks
A system can have multiple PTP clocks which are participating in
seperate and independent PTP clock domains. So far the kernel only
considers the PTP clock which is based on CLOCK TAI relevant as
that's the clock which drives the timekeeping adjustments via the
various user space daemons through adjtimex(2).
The non TAI based clock domains are accessible via the file
descriptor based posix clocks, but their usability is very limited.
They can't be accessed fast as they always go all the way out to
the hardware and they cannot be utilized in the kernel itself.
As Time Sensitive Networking (TSN) gains traction it is required to
provide fast user and kernel space access to these clocks.
The approach taken is to utilize the timekeeping and adjtimex(2)
infrastructure to provide this access in a similar way how the
kernel provides access to clock MONOTONIC, REALTIME etc.
Instead of creating a duplicated infrastructure this rework
converts timekeeping and adjtimex(2) into generic functionality
which operates on pointers to data structures instead of using
static variables.
This allows to provide time accessors and adjtimex(2) functionality
for the independent PTP clocks in a subsequent step.
- Consolidate hrtimer initialization
hrtimers are set up by initializing the data structure and then
seperately setting the callback function for historical reasons.
That's an extra unnecessary step and makes Rust support less
straight forward than it should be.
Provide a new set of hrtimer_setup*() functions and convert the
core code and a few usage sites of the less frequently used
interfaces over.
The bulk of the htimer_init() to hrtimer_setup() conversion is
already prepared and scheduled for the next merge window.
- Drivers:
- Ensure that the global timekeeping clocksource is utilizing the
cluster 0 timer on MIPS multi-cluster systems.
Otherwise CPUs on different clusters use their cluster specific
clocksource which is not guaranteed to be synchronized with
other clusters.
- Mostly boring cleanups, fixes, improvements and code movement"
* tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (140 commits)
posix-timers: Fix spurious warning on double enqueue versus do_exit()
clocksource/drivers/arm_arch_timer: Use of_property_present() for non-boolean properties
clocksource/drivers/gpx: Remove redundant casts
clocksource/drivers/timer-ti-dm: Fix child node refcount handling
dt-bindings: timer: actions,owl-timer: convert to YAML
clocksource/drivers/ralink: Add Ralink System Tick Counter driver
clocksource/drivers/mips-gic-timer: Always use cluster 0 counter as clocksource
clocksource/drivers/timer-ti-dm: Don't fail probe if int not found
clocksource/drivers:sp804: Make user selectable
clocksource/drivers/dw_apb: Remove unused dw_apb_clockevent functions
hrtimers: Delete hrtimer_init_on_stack()
alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()
io_uring: Switch to use hrtimer_setup_on_stack()
sched/idle: Switch to use hrtimer_setup_on_stack()
hrtimers: Delete hrtimer_init_sleeper_on_stack()
wait: Switch to use hrtimer_setup_sleeper_on_stack()
timers: Switch to use hrtimer_setup_sleeper_on_stack()
net: pktgen: Switch to use hrtimer_setup_sleeper_on_stack()
futex: Switch to use hrtimer_setup_sleeper_on_stack()
fs/aio: Switch to use hrtimer_setup_sleeper_on_stack()
...
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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
...
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Merge tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux
Pull block updates from Jens Axboe:
- NVMe updates via Keith:
- Use uring_cmd helper (Pavel)
- Host Memory Buffer allocation enhancements (Christoph)
- Target persistent reservation support (Guixin)
- Persistent reservation tracing (Guixen)
- NVMe 2.1 specification support (Keith)
- Rotational Meta Support (Matias, Wang, Keith)
- Volatile cache detection enhancment (Guixen)
- MD updates via Song:
- Maintainers update
- raid5 sync IO fix
- Enhance handling of faulty and blocked devices
- raid5-ppl atomic improvement
- md-bitmap fix
- Support for manually defining embedded partition tables
- Zone append fixes and cleanups
- Stop sending the queued requests in the plug list to the driver
->queue_rqs() handle in reverse order.
- Zoned write plug cleanups
- Cleanups disk stats tracking and add support for disk stats for
passthrough IO
- Add preparatory support for file system atomic writes
- Add lockdep support for queue freezing. Already found a bunch of
issues, and some fixes for that are in here. More will be coming.
- Fix race between queue stopping/quiescing and IO queueing
- ublk recovery improvements
- Fix ublk mmap for 64k pages
- Various fixes and cleanups
* tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux: (118 commits)
MAINTAINERS: Update git tree for mdraid subsystem
block: make struct rq_list available for !CONFIG_BLOCK
block/genhd: use seq_put_decimal_ull for diskstats decimal values
block: don't reorder requests in blk_mq_add_to_batch
block: don't reorder requests in blk_add_rq_to_plug
block: add a rq_list type
block: remove rq_list_move
virtio_blk: reverse request order in virtio_queue_rqs
nvme-pci: reverse request order in nvme_queue_rqs
btrfs: validate queue limits
block: export blk_validate_limits
nvmet: add tracing of reservation commands
nvme: parse reservation commands's action and rtype to string
nvmet: report ns's vwc not present
md/raid5: Increase r5conf.cache_name size
block: remove the ioprio field from struct request
block: remove the write_hint field from struct request
nvme: check ns's volatile write cache not present
nvme: add rotational support
nvme: use command set independent id ns if available
...
Replace the semi-open coded request list helpers with a proper rq_list
type that mirrors the bio_list and has head and tail pointers. Besides
better type safety this actually allows to insert at the tail of the
list, which will be useful soon.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241113152050.157179-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
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>
A new hybrid poll is implemented on the io_uring layer. Once an IO is
issued, it will not poll immediately, but rather block first and re-run
before IO complete, then poll to reap IO. While this poll method could
be a suboptimal solution when running on a single thread, it offers
performance lower than regular polling but higher than IRQ, and CPU
utilization is also lower than polling.
To use hybrid polling, the ring must be setup with both the
IORING_SETUP_IOPOLL and IORING_SETUP_HYBRID)IOPOLL flags set. Hybrid
polling has the same restrictions as IOPOLL, in that commands must
explicitly support it.
Signed-off-by: hexue <xue01.he@samsung.com>
Link: https://lore.kernel.org/r/20241101091957.564220-2-xue01.he@samsung.com
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>
When io_uring starts a write, it'll call kiocb_start_write() to bump the
super block rwsem, preventing any freezes from happening while that
write is in-flight. The freeze side will grab that rwsem for writing,
excluding any new writers from happening and waiting for existing writes
to finish. But io_uring unconditionally uses kiocb_start_write(), which
will block if someone is currently attempting to freeze the mount point.
This causes a deadlock where freeze is waiting for previous writes to
complete, but the previous writes cannot complete, as the task that is
supposed to complete them is blocked waiting on starting a new write.
This results in the following stuck trace showing that dependency with
the write blocked starting a new write:
task:fio state:D stack:0 pid:886 tgid:886 ppid:876
Call trace:
__switch_to+0x1d8/0x348
__schedule+0x8e8/0x2248
schedule+0x110/0x3f0
percpu_rwsem_wait+0x1e8/0x3f8
__percpu_down_read+0xe8/0x500
io_write+0xbb8/0xff8
io_issue_sqe+0x10c/0x1020
io_submit_sqes+0x614/0x2110
__arm64_sys_io_uring_enter+0x524/0x1038
invoke_syscall+0x74/0x268
el0_svc_common.constprop.0+0x160/0x238
do_el0_svc+0x44/0x60
el0_svc+0x44/0xb0
el0t_64_sync_handler+0x118/0x128
el0t_64_sync+0x168/0x170
INFO: task fsfreeze:7364 blocked for more than 15 seconds.
Not tainted 6.12.0-rc5-00063-g76aaf945701c #7963
with the attempting freezer stuck trying to grab the rwsem:
task:fsfreeze state:D stack:0 pid:7364 tgid:7364 ppid:995
Call trace:
__switch_to+0x1d8/0x348
__schedule+0x8e8/0x2248
schedule+0x110/0x3f0
percpu_down_write+0x2b0/0x680
freeze_super+0x248/0x8a8
do_vfs_ioctl+0x149c/0x1b18
__arm64_sys_ioctl+0xd0/0x1a0
invoke_syscall+0x74/0x268
el0_svc_common.constprop.0+0x160/0x238
do_el0_svc+0x44/0x60
el0_svc+0x44/0xb0
el0t_64_sync_handler+0x118/0x128
el0t_64_sync+0x168/0x170
Fix this by having the io_uring side honor IOCB_NOWAIT, and only attempt a
blocking grab of the super block rwsem if it isn't set. For normal issue
where IOCB_NOWAIT would always be set, this returns -EAGAIN which will
have io_uring core issue a blocking attempt of the write. That will in
turn also get completions run, ensuring forward progress.
Since freezing requires CAP_SYS_ADMIN in the first place, this isn't
something that can be triggered by a regular user.
Cc: stable@vger.kernel.org # 5.10+
Reported-by: Peter Mann <peter.mann@sh.cz>
Link: https://lore.kernel.org/io-uring/38c94aec-81c9-4f62-b44e-1d87f5597644@sh.cz
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 assigned in the same function that it's being used, get rid of
it. A local variable will do just fine.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous commit improved how !FMODE_NOWAIT is dealt with, but
inadvertently negated a check whilst doing so. This caused -EAGAIN to be
returned from reading files with O_NONBLOCK set. Fix up the check for
REQ_F_SUPPORT_NOWAIT.
Reported-by: Julian Orth <ju.orth@gmail.com>
Link: https://github.com/axboe/liburing/issues/1270
Fixes: f7c9134385 ("io_uring/rw: allow pollable non-blocking attempts for !FMODE_NOWAIT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The checking for whether or not io_uring can do a non-blocking read or
write attempt is gated on FMODE_NOWAIT. However, if the file is
pollable, it's feasible to just check if it's currently in a state in
which it can sanely receive or send _some_ data.
This avoids unnecessary io-wq punts, and repeated worthless retries
before doing that punt, by assuming that some data can get delivered
or received if poll tells us that is true. It also allows multishot
reads to properly work with these types of files, enabling a bit of
a cleanup of the logic that:
c9d952b910 ("io_uring/rw: fix cflags posting for single issue multishot read")
had to put in place.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If multishot gets disabled, and hence the request will get terminated
rather than persist for more iterations, then posting the CQE with the
right cflags is still important. Most notably, the buffer reference
needs to be included.
Refactor the return of __io_read() a bit, so that the provided buffer
is always put correctly, and hence returned to the application.
Reported-by: Sharon Rosner <Sharon Rosner>
Link: https://github.com/axboe/liburing/issues/1257
Cc: stable@vger.kernel.org
Fixes: 2a975d426c ("io_uring/rw: don't allow multishot reads without NOWAIT support")
Signed-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: a08d195b58 ("io_uring/rw: split io_read() into a helper")
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>
An atomic write is a write issued with torn-write protection, meaning
that for a power failure or any other hardware failure, all or none of the
data from the write will be stored, but never a mix of old and new data.
Userspace may add flag RWF_ATOMIC to pwritev2() to indicate that the
write is to be issued with torn-write prevention, according to special
alignment and length rules.
For any syscall interface utilizing struct iocb, add IOCB_ATOMIC for
iocb->ki_flags field to indicate the same.
A call to statx will give the relevant atomic write info for a file:
- atomic_write_unit_min
- atomic_write_unit_max
- atomic_write_segments_max
Both min and max values must be a power-of-2.
Applications can avail of atomic write feature by ensuring that the total
length of a write is a power-of-2 in size and also sized between
atomic_write_unit_min and atomic_write_unit_max, inclusive. Applications
must ensure that the write is at a naturally-aligned offset in the file
wrt the total write length. The value in atomic_write_segments_max
indicates the upper limit for IOV_ITER iovcnt.
Add file mode flag FMODE_CAN_ATOMIC_WRITE, so files which do not have the
flag set will have RWF_ATOMIC rejected and not just ignored.
Add a type argument to kiocb_set_rw_flags() to allows reads which have
RWF_ATOMIC set to be rejected.
Helper function generic_atomic_write_valid() can be used by FSes to verify
compliant writes. There we check for iov_iter type is for ubuf, which
implies iovcnt==1 for pwritev2(), which is an initial restriction for
atomic_write_segments_max. Initially the only user will be bdev file
operations write handler. We will rely on the block BIO submission path to
ensure write sizes are compliant for the bdev, so we don't need to check
atomic writes sizes yet.
Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
jpg: merge into single patch and much rewrite
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-4-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc vfs updates from Al Viro:
"Assorted commits that had missed the last merge window..."
* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
remove call_{read,write}_iter() functions
do_dentry_open(): kill inode argument
kernel_file_open(): get rid of inode argument
get_file_rcu(): no need to check for NULL separately
fd_is_open(): move to fs/file.c
close_on_exec(): pass files_struct instead of fdtable
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Merge tag 'for-6.10/io_uring-20240511' of git://git.kernel.dk/linux
Pull io_uring updates from Jens Axboe:
- Greatly improve send zerocopy performance, by enabling coalescing of
sent buffers.
MSG_ZEROCOPY already does this with send(2) and sendmsg(2), but the
io_uring side did not. In local testing, the crossover point for send
zerocopy being faster is now around 3000 byte packets, and it
performs better than the sync syscall variants as well.
This feature relies on a shared branch with net-next, which was
pulled into both branches.
- Unification of how async preparation is done across opcodes.
Previously, opcodes that required extra memory for async retry would
allocate that as needed, using on-stack state until that was the
case. If async retry was needed, the on-stack state was adjusted
appropriately for a retry and then copied to the allocated memory.
This led to some fragile and ugly code, particularly for read/write
handling, and made storage retries more difficult than they needed to
be. Allocate the memory upfront, as it's cheap from our pools, and
use that state consistently both initially and also from the retry
side.
- Move away from using remap_pfn_range() for mapping the rings.
This is really not the right interface to use and can cause lifetime
issues or leaks. Additionally, it means the ring sq/cq arrays need to
be physically contigious, which can cause problems in production with
larger rings when services are restarted, as memory can be very
fragmented at that point.
Move to using vm_insert_page(s) for the ring sq/cq arrays, and apply
the same treatment to mapped ring provided buffers. This also helps
unify the code we have dealing with allocating and mapping memory.
Hard to see in the diffstat as we're adding a few features as well,
but this kills about ~400 lines of code from the codebase as well.
- Add support for bundles for send/recv.
When used with provided buffers, bundles support sending or receiving
more than one buffer at the time, improving the efficiency by only
needing to call into the networking stack once for multiple sends or
receives.
- Tweaks for our accept operations, supporting both a DONTWAIT flag for
skipping poll arm and retry if we can, and a POLLFIRST flag that the
application can use to skip the initial accept attempt and rely
purely on poll for triggering the operation. Both of these have
identical flags on the receive side already.
- Make the task_work ctx locking unconditional.
We had various code paths here that would do a mix of lock/trylock
and set the task_work state to whether or not it was locked. All of
that goes away, we lock it unconditionally and get rid of the state
flag indicating whether it's locked or not.
The state struct still exists as an empty type, can go away in the
future.
- Add support for specifying NOP completion values, allowing it to be
used for error handling testing.
- Use set/test bit for io-wq worker flags. Not strictly needed, but
also doesn't hurt and helps silence a KCSAN warning.
- Cleanups for io-wq locking and work assignments, closing a tiny race
where cancelations would not be able to find the work item reliably.
- Misc fixes, cleanups, and improvements
* tag 'for-6.10/io_uring-20240511' of git://git.kernel.dk/linux: (97 commits)
io_uring: support to inject result for NOP
io_uring: fail NOP if non-zero op flags is passed in
io_uring/net: add IORING_ACCEPT_POLL_FIRST flag
io_uring/net: add IORING_ACCEPT_DONTWAIT flag
io_uring/filetable: don't unnecessarily clear/reset bitmap
io_uring/io-wq: Use set_bit() and test_bit() at worker->flags
io_uring/msg_ring: cleanup posting to IOPOLL vs !IOPOLL ring
io_uring: Require zeroed sqe->len on provided-buffers send
io_uring/notif: disable LAZY_WAKE for linked notifs
io_uring/net: fix sendzc lazy wake polling
io_uring/msg_ring: reuse ctx->submitter_task read using READ_ONCE instead of re-reading it
io_uring/rw: reinstate thread check for retries
io_uring/notif: implement notification stacking
io_uring/notif: simplify io_notif_flush()
net: add callback for setting a ubuf_info to skb
net: extend ubuf_info callback to ops structure
io_uring/net: support bundles for recv
io_uring/net: support bundles for send
io_uring/kbuf: add helpers for getting/peeking multiple buffers
io_uring/net: add provided buffer support for IORING_OP_SEND
...
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Merge tag 'vfs-6.10.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual fses.
Features:
- Free up FMODE_* bits. I've freed up bits 6, 7, 8, and 24. That
means we now have six free FMODE_* bits in total (but bit #6
already got used for FMODE_WRITE_RESTRICTED)
- Add FOP_HUGE_PAGES flag (follow-up to FMODE_* cleanup)
- Add fd_raw cleanup class so we can make use of automatic cleanup
provided by CLASS(fd_raw, f)(fd) for O_PATH fds as well
- Optimize seq_puts()
- Simplify __seq_puts()
- Add new anon_inode_getfile_fmode() api to allow specifying f_mode
instead of open-coding it in multiple places
- Annotate struct file_handle with __counted_by() and use
struct_size()
- Warn in get_file() whether f_count resurrection from zero is
attempted (epoll/drm discussion)
- Folio-sophize aio
- Export the subvolume id in statx() for both btrfs and bcachefs
- Relax linkat(AT_EMPTY_PATH) requirements
- Add F_DUPFD_QUERY fcntl() allowing to compare two file descriptors
for dup*() equality replacing kcmp()
Cleanups:
- Compile out swapfile inode checks when swap isn't enabled
- Use (1 << n) notation for FMODE_* bitshifts for clarity
- Remove redundant variable assignment in fs/direct-io
- Cleanup uses of strncpy in orangefs
- Speed up and cleanup writeback
- Move fsparam_string_empty() helper into header since it's currently
open-coded in multiple places
- Add kernel-doc comments to proc_create_net_data_write()
- Don't needlessly read dentry->d_flags twice
Fixes:
- Fix out-of-range warning in nilfs2
- Fix ecryptfs overflow due to wrong encryption packet size
calculation
- Fix overly long line in xfs file_operations (follow-up to FMODE_*
cleanup)
- Don't raise FOP_BUFFER_{R,W}ASYNC for directories in xfs (follow-up
to FMODE_* cleanup)
- Don't call xfs_file_open from xfs_dir_open (follow-up to FMODE_*
cleanup)
- Fix stable offset api to prevent endless loops
- Fix afs file server rotations
- Prevent xattr node from overflowing the eraseblock in jffs2
- Move fdinfo PTRACE_MODE_READ procfs check into the .permission()
operation instead of .open() operation since this caused userspace
regressions"
* tag 'vfs-6.10.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (39 commits)
afs: Fix fileserver rotation getting stuck
selftests: add F_DUPDFD_QUERY selftests
fcntl: add F_DUPFD_QUERY fcntl()
file: add fd_raw cleanup class
fs: WARN when f_count resurrection is attempted
seq_file: Simplify __seq_puts()
seq_file: Optimize seq_puts()
proc: Move fdinfo PTRACE_MODE_READ check into the inode .permission operation
fs: Create anon_inode_getfile_fmode()
xfs: don't call xfs_file_open from xfs_dir_open
xfs: drop fop_flags for directories
xfs: fix overly long line in the file_operations
shmem: Fix shmem_rename2()
libfs: Add simple_offset_rename() API
libfs: Fix simple_offset_rename_exchange()
jffs2: prevent xattr node from overflowing the eraseblock
vfs, swap: compile out IS_SWAPFILE() on swapless configs
vfs: relax linkat() AT_EMPTY_PATH - aka flink() - requirements
fs/direct-io: remove redundant assignment to variable retval
fs/dcache: Re-use value stored to dentry->d_flags instead of re-reading
...
Allowing retries for everything is arguably the right thing to do, now
that every command type is async read from the start. But it's exposed a
few issues around missing check for a retry (which cca6571381 exposed),
and the fixup commit for that isn't necessarily 100% sound in terms of
iov_iter state.
For now, just revert these two commits. This unfortunately then re-opens
the fact that -EAGAIN can get bubbled to userspace for some cases where
the kernel very well could just sanely retry them. But until we have all
the conditions covered around that, we cannot safely enable that.
This reverts commit df604d2ad4.
This reverts commit cca6571381.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A previous commit removed the checking on whether or not it was possible
to retry a request, since it's now possible to retry any of them. This
would previously have caused the request to have been ended with an error,
but now the retry condition can simply get lost instead.
Cleanup the retry handling and always just punt it to task_work, which
will queue it with io-wq appropriately.
Reported-by: Changhui Zhong <czhong@redhat.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Fixes: cca6571381 ("io_uring/rw: cleanup retry path")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
These have no clear purpose. This is effectively a revert of commit
bb7462b6fd ("vfs: use helpers for calling f_op->{read,write}_iter()").
The patch was created with the help of a coccinelle script.
Fixes: bb7462b6fd ("vfs: use helpers for calling f_op->{read,write}_iter()")
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently lists are being used to manage this, but best practice is
usually to have these in an array instead as that it cheaper to manage.
Outside of that detail, games are also played with KASAN as the list
is inside the cached entry itself.
Finally, all users of this need a struct io_cache_entry embedded in
their struct, which is union'ized with something else in there that
isn't used across the free -> realloc cycle.
Get rid of all of that, and simply have it be an array. This will not
change the memory used, as we're just trading an 8-byte member entry
for the per-elem array size.
This reduces the overhead of the recycled allocations, and it reduces
the amount of code code needed to support recycling to about half of
what it currently is.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Let the io_async_rw hold on to the iovec and reuse it, rather than always
allocate and free them.
Also enables KASAN for the iovec entries, so that reuse can be detected
even while they are in the cache.
While doing so, shrink io_async_rw by getting rid of the bigger embedded
fast iovec. Since iovecs are being recycled now, shrink it from 8 to 1.
This reduces the io_async_rw size from 264 to 160 bytes, a 40% reduction.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We no longer need to gate a potential retry on whether or not the
context matches our original task, as all read/write operations have
been fully prepared upfront. This means there's never any re-import
needed, and hence we can always retry requests.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
read/write requests try to put everything on the stack, and then alloc
and copy if a retry is needed. This necessitates a bunch of nasty code
that deals with intermediate state.
Get rid of this, and have the prep side setup everything that is needed
upfront, which greatly simplifies the opcode handlers.
This includes adding an alloc cache for io_async_rw, to make it cheap
to handle.
In terms of cost, this should be basically free and transparent. For
the worst case of {READ,WRITE}_FIXED which didn't need it before,
performance is unaffected in the normal peak workload that is being
used to test that. Still runs at 122M IOPS.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The restriction on multishot execution context disallowing io-wq is
driven by rules of io_fill_cqe_req_aux(), it should only be called in
the master task context, either from the syscall path or in task_work.
Since task_work now always takes the ctx lock implying
IO_URING_F_COMPLETE_DEFER, we can just assume that the function is
always called with its defer argument set to true.
Kill the argument. Also rename the function for more consistency as
"fill" in CQE related functions was usually meant for raw interfaces
only copying data into the CQ without any locking, waking the user
and other accounting "post" functions take care of.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/93423d106c33116c7d06bf277f651aa68b427328.1710799188.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
ctx is always locked for task_work now, so get rid of struct
io_tw_state::locked. Note I'm stopping one step before removing
io_tw_state altogether, which is not empty, because it still serves the
purpose of indicating which function is a tw callback and forcing users
not to invoke them carelessly out of a wrong context. The removal can
always be done later.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/e95e1ea116d0bfa54b656076e6a977bc221392a4.1710799188.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
kiocb_done() should care to specifically redirecting requests to io-wq.
Remove the hopping to tw to then queue an io-wq, return -EAGAIN and let
the core code io_uring handle offloading.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/413564e550fe23744a970e1783dfa566291b0e6f.1710799188.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There's a bunch of flags that are purely based on what the file
operations support while also never being conditionally set or unset.
IOW, they're not subject to change for individual files. Imho, such
flags don't need to live in f_mode they might as well live in the fops
structs itself. And the fops struct already has that lonely
mmap_supported_flags member. We might as well turn that into a generic
fop_flags member and move a few flags from FMODE_* space into FOP_*
space. That gets us four FMODE_* bits back and the ability for new
static flags that are about file ops to not have to live in FMODE_*
space but in their own FOP_* space. It's not the most beautiful thing
ever but it gets the job done. Yes, there'll be an additional pointer
chase but hopefully that won't matter for these flags.
I suspect there's a few more we can move into there and that we can also
redirect a bunch of new flag suggestions that follow this pattern into
the fop_flags field instead of f_mode.
Link: https://lore.kernel.org/r/20240328-gewendet-spargel-aa60a030ef74@brauner
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Supporting multishot reads requires support for NOWAIT, as the
alternative would be always having io-wq execute the work item whenever
the poll readiness triggered. Any fast file type will have NOWAIT
support (eg it understands both O_NONBLOCK and IOCB_NOWAIT). If the
given file type does not, then simply resort to single shot execution.
Cc: stable@vger.kernel.org
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If read multishot is being invoked from the poll retry handler, then we
should return IOU_ISSUE_SKIP_COMPLETE rather than -EAGAIN. If not, then
a CQE will be posted with -EAGAIN rather than triggering the retry when
the file is flagged as readable again.
Cc: stable@vger.kernel.org
Reported-by: Sargun Dhillon <sargun@meta.com>
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We disallow DEFER_TASKRUN multishots from running by io-wq, which is
checked by individual opcodes in the issue path. We can consolidate all
it in io_wq_submit_work() at the same time moving the checks out of the
hot path.
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e492f0f11588bb5aa11d7d24e6f53b7c7628afdb.1709905727.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We only use the flag for this purpose, so rename it accordingly. This
further prevents various other use cases of it, keeping it clean and
consistent. Then we can also check it in one spot, when it's being
attempted recycled, and remove some dead code in io_kbuf_recycle_ring().
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Changes to AF_UNIX trigger rebuild of io_uring, but io_uring does
not use AF_UNIX anymore.
Let's not include af_unix.h and instead include necessary headers.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240212234236.63714-1-kuniyu@amazon.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Any read/write opcode has needs_file == true, which means that we
would've failed the request long before reaching the issue stage if we
didn't successfully assign a file. This check has been dead forever,
and is really a leftover from generic code.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This adds a flag to avoid dipping dereferencing file and then f_op to
figure out if the file has a poll handler defined or not. We generally
call this at least twice for networked workloads, and if using ring
provided buffers, we do it on every buffer selection. Particularly the
latter is troublesome, as it's otherwise a very fast operation.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_read_mshot() always relies on poll triggering retries, and this works
fine as long as we do a retry per size of the buffer being read. The
buffer size is given by the size of the buffer(s) in the given buffer
group ID.
But if we're reading less than what is available, then we don't always
get to read everything that is available. For example, if the buffers
available are 32 bytes and we have 64 bytes to read, then we'll
correctly read the first 32 bytes and then wait for another poll trigger
before we attempt the next read. This next poll trigger may never
happen, in which case we just sit forever and never make progress, or it
may trigger at some point in the future, and now we're just delivering
the available data much later than we should have.
io_read_mshot() could do retries itself, but that is wasteful as we'll
be going through all of __io_read() again, and most likely in vain.
Rather than do that, bump our poll reference count and have
io_poll_check_events() do one more loop and check with vfs_poll() if we
have more data to read. If we do, io_read_mshot() will get invoked again
directly and we'll read the next chunk.
io_poll_multishot_retry() must only get called from inside
io_poll_issue(), which is our multishot retry handler, as we know we
already "own" the request at this point.
Cc: stable@vger.kernel.org
Link: https://github.com/axboe/liburing/issues/1041
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
