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OpenCloudOS-Kernel/fs/io_uring.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Shared application/kernel submission and completion ring pairs, for
* supporting fast/efficient IO.
*
* A note on the read/write ordering memory barriers that are matched between
* the application and kernel side.
*
* After the application reads the CQ ring tail, it must use an
* appropriate smp_rmb() to pair with the smp_wmb() the kernel uses
* before writing the tail (using smp_load_acquire to read the tail will
* do). It also needs a smp_mb() before updating CQ head (ordering the
* entry load(s) with the head store), pairing with an implicit barrier
* through a control-dependency in io_get_cqring (smp_store_release to
* store head will do). Failure to do so could lead to reading invalid
* CQ entries.
*
* Likewise, the application must use an appropriate smp_wmb() before
* writing the SQ tail (ordering SQ entry stores with the tail store),
* which pairs with smp_load_acquire in io_get_sqring (smp_store_release
* to store the tail will do). And it needs a barrier ordering the SQ
* head load before writing new SQ entries (smp_load_acquire to read
* head will do).
*
* When using the SQ poll thread (IORING_SETUP_SQPOLL), the application
* needs to check the SQ flags for IORING_SQ_NEED_WAKEUP *after*
* updating the SQ tail; a full memory barrier smp_mb() is needed
* between.
*
* Also see the examples in the liburing library:
*
* git://git.kernel.dk/liburing
*
* io_uring also uses READ/WRITE_ONCE() for _any_ store or load that happens
* from data shared between the kernel and application. This is done both
* for ordering purposes, but also to ensure that once a value is loaded from
* data that the application could potentially modify, it remains stable.
*
* Copyright (C) 2018-2019 Jens Axboe
* Copyright (c) 2018-2019 Christoph Hellwig
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/syscalls.h>
#include <linux/compat.h>
#include <linux/refcount.h>
#include <linux/uio.h>
#include <linux/sched/signal.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/mmu_context.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <linux/blkdev.h>
#include <linux/bvec.h>
#include <linux/net.h>
#include <net/sock.h>
#include <net/af_unix.h>
#include <net/scm.h>
#include <linux/anon_inodes.h>
#include <linux/sched/mm.h>
#include <linux/uaccess.h>
#include <linux/nospec.h>
#include <linux/sizes.h>
#include <linux/hugetlb.h>
#include <linux/highmem.h>
#include <linux/fs_struct.h>
#include <uapi/linux/io_uring.h>
#include "internal.h"
#define IORING_MAX_ENTRIES 32768
#define IORING_MAX_FIXED_FILES 1024
struct io_uring {
u32 head ____cacheline_aligned_in_smp;
u32 tail ____cacheline_aligned_in_smp;
};
/*
* This data is shared with the application through the mmap at offsets
* IORING_OFF_SQ_RING and IORING_OFF_CQ_RING.
*
* The offsets to the member fields are published through struct
* io_sqring_offsets when calling io_uring_setup.
*/
struct io_rings {
/*
* Head and tail offsets into the ring; the offsets need to be
* masked to get valid indices.
*
* The kernel controls head of the sq ring and the tail of the cq ring,
* and the application controls tail of the sq ring and the head of the
* cq ring.
*/
struct io_uring sq, cq;
/*
* Bitmasks to apply to head and tail offsets (constant, equals
* ring_entries - 1)
*/
u32 sq_ring_mask, cq_ring_mask;
/* Ring sizes (constant, power of 2) */
u32 sq_ring_entries, cq_ring_entries;
/*
* Number of invalid entries dropped by the kernel due to
* invalid index stored in array
*
* Written by the kernel, shouldn't be modified by the
* application (i.e. get number of "new events" by comparing to
* cached value).
*
* After a new SQ head value was read by the application this
* counter includes all submissions that were dropped reaching
* the new SQ head (and possibly more).
*/
u32 sq_dropped;
/*
* Runtime flags
*
* Written by the kernel, shouldn't be modified by the
* application.
*
* The application needs a full memory barrier before checking
* for IORING_SQ_NEED_WAKEUP after updating the sq tail.
*/
u32 sq_flags;
/*
* Number of completion events lost because the queue was full;
* this should be avoided by the application by making sure
* there are not more requests pending thatn there is space in
* the completion queue.
*
* Written by the kernel, shouldn't be modified by the
* application (i.e. get number of "new events" by comparing to
* cached value).
*
* As completion events come in out of order this counter is not
* ordered with any other data.
*/
u32 cq_overflow;
/*
* Ring buffer of completion events.
*
* The kernel writes completion events fresh every time they are
* produced, so the application is allowed to modify pending
* entries.
*/
struct io_uring_cqe cqes[] ____cacheline_aligned_in_smp;
};
struct io_mapped_ubuf {
u64 ubuf;
size_t len;
struct bio_vec *bvec;
unsigned int nr_bvecs;
};
struct async_list {
spinlock_t lock;
atomic_t cnt;
struct list_head list;
struct file *file;
off_t io_start;
size_t io_len;
};
struct io_ring_ctx {
struct {
struct percpu_ref refs;
} ____cacheline_aligned_in_smp;
struct {
unsigned int flags;
bool compat;
bool account_mem;
/*
* Ring buffer of indices into array of io_uring_sqe, which is
* mmapped by the application using the IORING_OFF_SQES offset.
*
* This indirection could e.g. be used to assign fixed
* io_uring_sqe entries to operations and only submit them to
* the queue when needed.
*
* The kernel modifies neither the indices array nor the entries
* array.
*/
u32 *sq_array;
unsigned cached_sq_head;
unsigned sq_entries;
unsigned sq_mask;
unsigned sq_thread_idle;
unsigned cached_sq_dropped;
struct io_uring_sqe *sq_sqes;
struct list_head defer_list;
struct list_head timeout_list;
} ____cacheline_aligned_in_smp;
/* IO offload */
struct workqueue_struct *sqo_wq[2];
struct task_struct *sqo_thread; /* if using sq thread polling */
struct mm_struct *sqo_mm;
wait_queue_head_t sqo_wait;
struct completion sqo_thread_started;
struct {
unsigned cached_cq_tail;
atomic_t cached_cq_overflow;
unsigned cq_entries;
unsigned cq_mask;
struct wait_queue_head cq_wait;
struct fasync_struct *cq_fasync;
struct eventfd_ctx *cq_ev_fd;
atomic_t cq_timeouts;
} ____cacheline_aligned_in_smp;
struct io_rings *rings;
/*
* If used, fixed file set. Writers must ensure that ->refs is dead,
* readers must ensure that ->refs is alive as long as the file* is
* used. Only updated through io_uring_register(2).
*/
struct file **user_files;
unsigned nr_user_files;
/* if used, fixed mapped user buffers */
unsigned nr_user_bufs;
struct io_mapped_ubuf *user_bufs;
struct user_struct *user;
const struct cred *creds;
struct completion ctx_done;
struct {
struct mutex uring_lock;
wait_queue_head_t wait;
} ____cacheline_aligned_in_smp;
struct {
spinlock_t completion_lock;
bool poll_multi_file;
/*
* ->poll_list is protected by the ctx->uring_lock for
* io_uring instances that don't use IORING_SETUP_SQPOLL.
* For SQPOLL, only the single threaded io_sq_thread() will
* manipulate the list, hence no extra locking is needed there.
*/
struct list_head poll_list;
struct list_head cancel_list;
} ____cacheline_aligned_in_smp;
struct async_list pending_async[2];
#if defined(CONFIG_UNIX)
struct socket *ring_sock;
#endif
struct list_head task_list;
spinlock_t task_lock;
};
struct sqe_submit {
const struct io_uring_sqe *sqe;
unsigned short index;
u32 sequence;
bool has_user;
bool needs_lock;
bool needs_fixed_file;
u8 opcode;
};
/*
* First field must be the file pointer in all the
* iocb unions! See also 'struct kiocb' in <linux/fs.h>
*/
struct io_poll_iocb {
struct file *file;
struct wait_queue_head *head;
__poll_t events;
bool done;
bool canceled;
struct wait_queue_entry wait;
};
struct io_timeout {
struct file *file;
struct hrtimer timer;
};
/*
* NOTE! Each of the iocb union members has the file pointer
* as the first entry in their struct definition. So you can
* access the file pointer through any of the sub-structs,
* or directly as just 'ki_filp' in this struct.
*/
struct io_kiocb {
union {
struct file *file;
struct kiocb rw;
struct io_poll_iocb poll;
struct io_timeout timeout;
};
struct sqe_submit submit;
struct io_ring_ctx *ctx;
struct list_head list;
struct list_head link_list;
unsigned int flags;
refcount_t refs;
#define REQ_F_NOWAIT 1 /* must not punt to workers */
#define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */
#define REQ_F_FIXED_FILE 4 /* ctx owns file */
#define REQ_F_SEQ_PREV 8 /* sequential with previous */
#define REQ_F_IO_DRAIN 16 /* drain existing IO first */
#define REQ_F_IO_DRAINED 32 /* drain done */
#define REQ_F_LINK 64 /* linked sqes */
#define REQ_F_LINK_DONE 128 /* linked sqes done */
#define REQ_F_FAIL_LINK 256 /* fail rest of links */
#define REQ_F_SHADOW_DRAIN 512 /* link-drain shadow req */
#define REQ_F_TIMEOUT 1024 /* timeout request */
#define REQ_F_ISREG 2048 /* regular file */
#define REQ_F_MUST_PUNT 4096 /* must be punted even for NONBLOCK */
#define REQ_F_TIMEOUT_NOSEQ 8192 /* no timeout sequence */
#define REQ_F_CANCEL 16384 /* cancel request */
unsigned long fsize;
u64 user_data;
u32 result;
u32 sequence;
struct files_struct *files;
struct fs_struct *fs;
struct work_struct work;
struct task_struct *work_task;
struct list_head task_list;
};
#define IO_PLUG_THRESHOLD 2
#define IO_IOPOLL_BATCH 8
struct io_submit_state {
struct blk_plug plug;
/*
* io_kiocb alloc cache
*/
void *reqs[IO_IOPOLL_BATCH];
unsigned int free_reqs;
unsigned int cur_req;
/*
* File reference cache
*/
struct file *file;
unsigned int fd;
unsigned int has_refs;
unsigned int used_refs;
unsigned int ios_left;
};
static void io_sq_wq_submit_work(struct work_struct *work);
static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
long res);
static void __io_free_req(struct io_kiocb *req);
static struct kmem_cache *req_cachep;
static const struct file_operations io_uring_fops;
struct sock *io_uring_get_socket(struct file *file)
{
#if defined(CONFIG_UNIX)
if (file->f_op == &io_uring_fops) {
struct io_ring_ctx *ctx = file->private_data;
return ctx->ring_sock->sk;
}
#endif
return NULL;
}
EXPORT_SYMBOL(io_uring_get_socket);
static void io_ring_ctx_ref_free(struct percpu_ref *ref)
{
struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
complete(&ctx->ctx_done);
}
static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
{
struct io_ring_ctx *ctx;
int i;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return NULL;
if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
kfree(ctx);
return NULL;
}
ctx->flags = p->flags;
init_waitqueue_head(&ctx->sqo_wait);
init_waitqueue_head(&ctx->cq_wait);
init_completion(&ctx->ctx_done);
init_completion(&ctx->sqo_thread_started);
mutex_init(&ctx->uring_lock);
init_waitqueue_head(&ctx->wait);
for (i = 0; i < ARRAY_SIZE(ctx->pending_async); i++) {
spin_lock_init(&ctx->pending_async[i].lock);
INIT_LIST_HEAD(&ctx->pending_async[i].list);
atomic_set(&ctx->pending_async[i].cnt, 0);
}
spin_lock_init(&ctx->completion_lock);
INIT_LIST_HEAD(&ctx->poll_list);
INIT_LIST_HEAD(&ctx->cancel_list);
INIT_LIST_HEAD(&ctx->defer_list);
INIT_LIST_HEAD(&ctx->timeout_list);
INIT_LIST_HEAD(&ctx->task_list);
spin_lock_init(&ctx->task_lock);
return ctx;
}
static void io_req_put_fs(struct io_kiocb *req)
{
struct fs_struct *fs = req->fs;
if (!fs)
return;
spin_lock(&req->fs->lock);
if (--fs->users)
fs = NULL;
spin_unlock(&req->fs->lock);
if (fs)
free_fs_struct(fs);
req->fs = NULL;
}
static inline bool __io_sequence_defer(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
return req->sequence != ctx->cached_cq_tail + ctx->cached_sq_dropped
+ atomic_read(&ctx->cached_cq_overflow);
}
static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
return false;
return __io_sequence_defer(ctx, req);
}
static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
req = list_first_entry_or_null(&ctx->defer_list, struct io_kiocb, list);
if (req && !io_sequence_defer(ctx, req)) {
list_del_init(&req->list);
return req;
}
return NULL;
}
static struct io_kiocb *io_get_timeout_req(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
req = list_first_entry_or_null(&ctx->timeout_list, struct io_kiocb, list);
if (req) {
if (req->flags & REQ_F_TIMEOUT_NOSEQ)
return NULL;
if (!__io_sequence_defer(ctx, req)) {
list_del_init(&req->list);
return req;
}
}
return NULL;
}
static void __io_commit_cqring(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
if (ctx->cached_cq_tail != READ_ONCE(rings->cq.tail)) {
/* order cqe stores with ring update */
smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
if (wq_has_sleeper(&ctx->cq_wait)) {
wake_up_interruptible(&ctx->cq_wait);
kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
}
}
}
static inline void io_queue_async_work(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
unsigned long flags;
int rw = 0;
if (req->submit.sqe) {
switch (req->submit.opcode) {
case IORING_OP_WRITEV:
case IORING_OP_WRITE_FIXED:
rw = !(req->rw.ki_flags & IOCB_DIRECT);
break;
}
}
if (req->work.func == io_sq_wq_submit_work) {
req->files = current->files;
spin_lock_irqsave(&ctx->task_lock, flags);
list_add(&req->task_list, &ctx->task_list);
req->work_task = NULL;
spin_unlock_irqrestore(&ctx->task_lock, flags);
}
queue_work(ctx->sqo_wq[rw], &req->work);
}
static void io_kill_timeout(struct io_kiocb *req)
{
int ret;
ret = hrtimer_try_to_cancel(&req->timeout.timer);
if (ret != -1) {
atomic_inc(&req->ctx->cq_timeouts);
list_del(&req->list);
io_cqring_fill_event(req->ctx, req->user_data, 0);
__io_free_req(req);
}
}
static void io_kill_timeouts(struct io_ring_ctx *ctx)
{
struct io_kiocb *req, *tmp;
spin_lock_irq(&ctx->completion_lock);
list_for_each_entry_safe(req, tmp, &ctx->timeout_list, list)
io_kill_timeout(req);
spin_unlock_irq(&ctx->completion_lock);
}
static void io_commit_cqring(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
while ((req = io_get_timeout_req(ctx)) != NULL)
io_kill_timeout(req);
__io_commit_cqring(ctx);
while ((req = io_get_deferred_req(ctx)) != NULL) {
if (req->flags & REQ_F_SHADOW_DRAIN) {
/* Just for drain, free it. */
__io_free_req(req);
continue;
}
req->flags |= REQ_F_IO_DRAINED;
io_queue_async_work(ctx, req);
}
}
static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
unsigned tail;
tail = ctx->cached_cq_tail;
/*
* writes to the cq entry need to come after reading head; the
* control dependency is enough as we're using WRITE_ONCE to
* fill the cq entry
*/
if (tail - READ_ONCE(rings->cq.head) == rings->cq_ring_entries)
return NULL;
ctx->cached_cq_tail++;
return &rings->cqes[tail & ctx->cq_mask];
}
static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
long res)
{
struct io_uring_cqe *cqe;
/*
* If we can't get a cq entry, userspace overflowed the
* submission (by quite a lot). Increment the overflow count in
* the ring.
*/
cqe = io_get_cqring(ctx);
if (cqe) {
WRITE_ONCE(cqe->user_data, ki_user_data);
WRITE_ONCE(cqe->res, res);
WRITE_ONCE(cqe->flags, 0);
} else {
WRITE_ONCE(ctx->rings->cq_overflow,
atomic_inc_return(&ctx->cached_cq_overflow));
}
}
static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
{
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
if (waitqueue_active(&ctx->sqo_wait))
wake_up(&ctx->sqo_wait);
if (ctx->cq_ev_fd)
eventfd_signal(ctx->cq_ev_fd, 1);
}
static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
long res)
{
unsigned long flags;
spin_lock_irqsave(&ctx->completion_lock, flags);
io_cqring_fill_event(ctx, user_data, res);
io_commit_cqring(ctx);
spin_unlock_irqrestore(&ctx->completion_lock, flags);
io_cqring_ev_posted(ctx);
}
static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
struct io_submit_state *state)
{
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
struct io_kiocb *req;
if (!percpu_ref_tryget(&ctx->refs))
return NULL;
if (!state) {
req = kmem_cache_alloc(req_cachep, gfp);
if (unlikely(!req))
goto out;
} else if (!state->free_reqs) {
size_t sz;
int ret;
sz = min_t(size_t, state->ios_left, ARRAY_SIZE(state->reqs));
ret = kmem_cache_alloc_bulk(req_cachep, gfp, sz, state->reqs);
/*
* Bulk alloc is all-or-nothing. If we fail to get a batch,
* retry single alloc to be on the safe side.
*/
if (unlikely(ret <= 0)) {
state->reqs[0] = kmem_cache_alloc(req_cachep, gfp);
if (!state->reqs[0])
goto out;
ret = 1;
}
state->free_reqs = ret - 1;
state->cur_req = 1;
req = state->reqs[0];
} else {
req = state->reqs[state->cur_req];
state->free_reqs--;
state->cur_req++;
}
INIT_LIST_HEAD(&req->task_list);
req->file = NULL;
req->ctx = ctx;
req->flags = 0;
/* one is dropped after submission, the other at completion */
refcount_set(&req->refs, 2);
req->result = 0;
req->fs = NULL;
return req;
out:
percpu_ref_put(&ctx->refs);
return NULL;
}
static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
{
if (*nr) {
kmem_cache_free_bulk(req_cachep, *nr, reqs);
percpu_ref_put_many(&ctx->refs, *nr);
*nr = 0;
}
}
static void __io_free_req(struct io_kiocb *req)
{
io_req_put_fs(req);
if (req->file && !(req->flags & REQ_F_FIXED_FILE))
fput(req->file);
percpu_ref_put(&req->ctx->refs);
kmem_cache_free(req_cachep, req);
}
static void io_req_link_next(struct io_kiocb *req)
{
struct io_kiocb *nxt;
/*
* The list should never be empty when we are called here. But could
* potentially happen if the chain is messed up, check to be on the
* safe side.
*/
nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, list);
if (nxt) {
list_del(&nxt->list);
if (!list_empty(&req->link_list)) {
INIT_LIST_HEAD(&nxt->link_list);
list_splice(&req->link_list, &nxt->link_list);
nxt->flags |= REQ_F_LINK;
}
nxt->flags |= REQ_F_LINK_DONE;
INIT_WORK(&nxt->work, io_sq_wq_submit_work);
io_queue_async_work(req->ctx, nxt);
}
}
/*
* Called if REQ_F_LINK is set, and we fail the head request
*/
static void io_fail_links(struct io_kiocb *req)
{
struct io_kiocb *link;
while (!list_empty(&req->link_list)) {
link = list_first_entry(&req->link_list, struct io_kiocb, list);
list_del(&link->list);
io_cqring_add_event(req->ctx, link->user_data, -ECANCELED);
__io_free_req(link);
}
}
static void io_free_req(struct io_kiocb *req)
{
/*
* If LINK is set, we have dependent requests in this chain. If we
* didn't fail this request, queue the first one up, moving any other
* dependencies to the next request. In case of failure, fail the rest
* of the chain.
*/
if (req->flags & REQ_F_LINK) {
if (req->flags & REQ_F_FAIL_LINK)
io_fail_links(req);
else
io_req_link_next(req);
}
__io_free_req(req);
}
static void io_put_req(struct io_kiocb *req)
{
if (refcount_dec_and_test(&req->refs))
io_free_req(req);
}
static unsigned io_cqring_events(struct io_rings *rings)
{
/* See comment at the top of this file */
smp_rmb();
return READ_ONCE(rings->cq.tail) - READ_ONCE(rings->cq.head);
}
static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
/* make sure SQ entry isn't read before tail */
return smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
}
/*
* Find and free completed poll iocbs
*/
static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
struct list_head *done)
{
void *reqs[IO_IOPOLL_BATCH];
struct io_kiocb *req;
int to_free;
to_free = 0;
while (!list_empty(done)) {
req = list_first_entry(done, struct io_kiocb, list);
list_del(&req->list);
io_cqring_fill_event(ctx, req->user_data, req->result);
(*nr_events)++;
if (refcount_dec_and_test(&req->refs)) {
/* If we're not using fixed files, we have to pair the
* completion part with the file put. Use regular
* completions for those, only batch free for fixed
* file and non-linked commands.
*/
if ((req->flags & (REQ_F_FIXED_FILE|REQ_F_LINK)) ==
REQ_F_FIXED_FILE) {
reqs[to_free++] = req;
if (to_free == ARRAY_SIZE(reqs))
io_free_req_many(ctx, reqs, &to_free);
} else {
io_free_req(req);
}
}
}
io_commit_cqring(ctx);
io_free_req_many(ctx, reqs, &to_free);
}
static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
long min)
{
struct io_kiocb *req, *tmp;
LIST_HEAD(done);
bool spin;
int ret;
/*
* Only spin for completions if we don't have multiple devices hanging
* off our complete list, and we're under the requested amount.
*/
spin = !ctx->poll_multi_file && *nr_events < min;
ret = 0;
list_for_each_entry_safe(req, tmp, &ctx->poll_list, list) {
struct kiocb *kiocb = &req->rw;
/*
* Move completed entries to our local list. If we find a
* request that requires polling, break out and complete
* the done list first, if we have entries there.
*/
if (req->flags & REQ_F_IOPOLL_COMPLETED) {
list_move_tail(&req->list, &done);
continue;
}
if (!list_empty(&done))
break;
ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
if (ret < 0)
break;
if (ret && spin)
spin = false;
ret = 0;
}
if (!list_empty(&done))
io_iopoll_complete(ctx, nr_events, &done);
return ret;
}
/*
* Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
* non-spinning poll check - we'll still enter the driver poll loop, but only
* as a non-spinning completion check.
*/
static int io_iopoll_getevents(struct io_ring_ctx *ctx, unsigned int *nr_events,
long min)
{
while (!list_empty(&ctx->poll_list) && !need_resched()) {
int ret;
ret = io_do_iopoll(ctx, nr_events, min);
if (ret < 0)
return ret;
if (!min || *nr_events >= min)
return 0;
}
return 1;
}
/*
* We can't just wait for polled events to come to us, we have to actively
* find and complete them.
*/
static void io_iopoll_reap_events(struct io_ring_ctx *ctx)
{
if (!(ctx->flags & IORING_SETUP_IOPOLL))
return;
mutex_lock(&ctx->uring_lock);
while (!list_empty(&ctx->poll_list)) {
unsigned int nr_events = 0;
io_iopoll_getevents(ctx, &nr_events, 1);
/*
* Ensure we allow local-to-the-cpu processing to take place,
* in this case we need to ensure that we reap all events.
*/
cond_resched();
}
mutex_unlock(&ctx->uring_lock);
}
static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
long min)
{
int iters = 0, ret = 0;
/*
* We disallow the app entering submit/complete with polling, but we
* still need to lock the ring to prevent racing with polled issue
* that got punted to a workqueue.
*/
mutex_lock(&ctx->uring_lock);
do {
int tmin = 0;
/*
* Don't enter poll loop if we already have events pending.
* If we do, we can potentially be spinning for commands that
* already triggered a CQE (eg in error).
*/
if (io_cqring_events(ctx->rings))
break;
/*
* If a submit got punted to a workqueue, we can have the
* application entering polling for a command before it gets
* issued. That app will hold the uring_lock for the duration
* of the poll right here, so we need to take a breather every
* now and then to ensure that the issue has a chance to add
* the poll to the issued list. Otherwise we can spin here
* forever, while the workqueue is stuck trying to acquire the
* very same mutex.
*/
if (!(++iters & 7)) {
mutex_unlock(&ctx->uring_lock);
mutex_lock(&ctx->uring_lock);
}
if (*nr_events < min)
tmin = min - *nr_events;
ret = io_iopoll_getevents(ctx, nr_events, tmin);
if (ret <= 0)
break;
ret = 0;
} while (min && !*nr_events && !need_resched());
mutex_unlock(&ctx->uring_lock);
return ret;
}
static void kiocb_end_write(struct io_kiocb *req)
{
/*
* Tell lockdep we inherited freeze protection from submission
* thread.
*/
if (req->flags & REQ_F_ISREG) {
struct inode *inode = file_inode(req->file);
__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
}
file_end_write(req->file);
}
static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
{
struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
if (kiocb->ki_flags & IOCB_WRITE)
kiocb_end_write(req);
if ((req->flags & REQ_F_LINK) && res != req->result)
req->flags |= REQ_F_FAIL_LINK;
io_cqring_add_event(req->ctx, req->user_data, res);
io_put_req(req);
}
static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
{
struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
if (kiocb->ki_flags & IOCB_WRITE)
kiocb_end_write(req);
if ((req->flags & REQ_F_LINK) && res != req->result)
req->flags |= REQ_F_FAIL_LINK;
req->result = res;
if (res != -EAGAIN)
req->flags |= REQ_F_IOPOLL_COMPLETED;
}
/*
* After the iocb has been issued, it's safe to be found on the poll list.
* Adding the kiocb to the list AFTER submission ensures that we don't
* find it from a io_iopoll_getevents() thread before the issuer is done
* accessing the kiocb cookie.
*/
static void io_iopoll_req_issued(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
/*
* Track whether we have multiple files in our lists. This will impact
* how we do polling eventually, not spinning if we're on potentially
* different devices.
*/
if (list_empty(&ctx->poll_list)) {
ctx->poll_multi_file = false;
} else if (!ctx->poll_multi_file) {
struct io_kiocb *list_req;
list_req = list_first_entry(&ctx->poll_list, struct io_kiocb,
list);
if (list_req->rw.ki_filp != req->rw.ki_filp)
ctx->poll_multi_file = true;
}
/*
* For fast devices, IO may have already completed. If it has, add
* it to the front so we find it first.
*/
if (req->flags & REQ_F_IOPOLL_COMPLETED)
list_add(&req->list, &ctx->poll_list);
else
list_add_tail(&req->list, &ctx->poll_list);
}
static void io_file_put(struct io_submit_state *state)
{
if (state->file) {
int diff = state->has_refs - state->used_refs;
if (diff)
fput_many(state->file, diff);
state->file = NULL;
}
}
/*
* Get as many references to a file as we have IOs left in this submission,
* assuming most submissions are for one file, or at least that each file
* has more than one submission.
*/
static struct file *io_file_get(struct io_submit_state *state, int fd)
{
if (!state)
return fget(fd);
if (state->file) {
if (state->fd == fd) {
state->used_refs++;
state->ios_left--;
return state->file;
}
io_file_put(state);
}
state->file = fget_many(fd, state->ios_left);
if (!state->file)
return NULL;
state->fd = fd;
state->has_refs = state->ios_left;
state->used_refs = 1;
state->ios_left--;
return state->file;
}
/*
* If we tracked the file through the SCM inflight mechanism, we could support
* any file. For now, just ensure that anything potentially problematic is done
* inline.
*/
static bool io_file_supports_async(struct file *file)
{
umode_t mode = file_inode(file)->i_mode;
if (S_ISBLK(mode) || S_ISCHR(mode))
return true;
if (S_ISREG(mode) && file->f_op != &io_uring_fops)
return true;
return false;
}
static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
bool force_nonblock)
{
const struct io_uring_sqe *sqe = s->sqe;
struct io_ring_ctx *ctx = req->ctx;
struct kiocb *kiocb = &req->rw;
unsigned ioprio;
int ret;
if (!req->file)
return -EBADF;
if (S_ISREG(file_inode(req->file)->i_mode))
req->flags |= REQ_F_ISREG;
if (force_nonblock)
req->fsize = rlimit(RLIMIT_FSIZE);
/*
* If the file doesn't support async, mark it as REQ_F_MUST_PUNT so
* we know to async punt it even if it was opened O_NONBLOCK
*/
if (force_nonblock && !io_file_supports_async(req->file)) {
req->flags |= REQ_F_MUST_PUNT;
return -EAGAIN;
}
kiocb->ki_pos = READ_ONCE(sqe->off);
kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
ioprio = READ_ONCE(sqe->ioprio);
if (ioprio) {
ret = ioprio_check_cap(ioprio);
if (ret)
return ret;
kiocb->ki_ioprio = ioprio;
} else
kiocb->ki_ioprio = get_current_ioprio();
ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
if (unlikely(ret))
return ret;
/* don't allow async punt if RWF_NOWAIT was requested */
if ((kiocb->ki_flags & IOCB_NOWAIT) ||
(req->file->f_flags & O_NONBLOCK))
req->flags |= REQ_F_NOWAIT;
if (force_nonblock)
kiocb->ki_flags |= IOCB_NOWAIT;
if (ctx->flags & IORING_SETUP_IOPOLL) {
if (!(kiocb->ki_flags & IOCB_DIRECT) ||
!kiocb->ki_filp->f_op->iopoll)
return -EOPNOTSUPP;
kiocb->ki_flags |= IOCB_HIPRI;
kiocb->ki_complete = io_complete_rw_iopoll;
req->result = 0;
} else {
if (kiocb->ki_flags & IOCB_HIPRI)
return -EINVAL;
kiocb->ki_complete = io_complete_rw;
}
return 0;
}
static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
{
switch (ret) {
case -EIOCBQUEUED:
break;
case -ERESTARTSYS:
case -ERESTARTNOINTR:
case -ERESTARTNOHAND:
case -ERESTART_RESTARTBLOCK:
/*
* We can't just restart the syscall, since previously
* submitted sqes may already be in progress. Just fail this
* IO with EINTR.
*/
ret = -EINTR;
/* fall through */
default:
kiocb->ki_complete(kiocb, ret, 0);
}
}
static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
const struct io_uring_sqe *sqe,
struct iov_iter *iter)
{
size_t len = READ_ONCE(sqe->len);
struct io_mapped_ubuf *imu;
unsigned index, buf_index;
size_t offset;
u64 buf_addr;
/* attempt to use fixed buffers without having provided iovecs */
if (unlikely(!ctx->user_bufs))
return -EFAULT;
buf_index = READ_ONCE(sqe->buf_index);
if (unlikely(buf_index >= ctx->nr_user_bufs))
return -EFAULT;
index = array_index_nospec(buf_index, ctx->nr_user_bufs);
imu = &ctx->user_bufs[index];
buf_addr = READ_ONCE(sqe->addr);
/* overflow */
if (buf_addr + len < buf_addr)
return -EFAULT;
/* not inside the mapped region */
if (buf_addr < imu->ubuf || buf_addr + len > imu->ubuf + imu->len)
return -EFAULT;
/*
* May not be a start of buffer, set size appropriately
* and advance us to the beginning.
*/
offset = buf_addr - imu->ubuf;
iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
if (offset) {
/*
* Don't use iov_iter_advance() here, as it's really slow for
* using the latter parts of a big fixed buffer - it iterates
* over each segment manually. We can cheat a bit here, because
* we know that:
*
* 1) it's a BVEC iter, we set it up
* 2) all bvecs are PAGE_SIZE in size, except potentially the
* first and last bvec
*
* So just find our index, and adjust the iterator afterwards.
* If the offset is within the first bvec (or the whole first
* bvec, just use iov_iter_advance(). This makes it easier
* since we can just skip the first segment, which may not
* be PAGE_SIZE aligned.
*/
const struct bio_vec *bvec = imu->bvec;
if (offset <= bvec->bv_len) {
iov_iter_advance(iter, offset);
} else {
unsigned long seg_skip;
/* skip first vec */
offset -= bvec->bv_len;
seg_skip = 1 + (offset >> PAGE_SHIFT);
iter->bvec = bvec + seg_skip;
iter->nr_segs -= seg_skip;
iter->count -= bvec->bv_len + offset;
iter->iov_offset = offset & ~PAGE_MASK;
}
}
return len;
}
static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
struct io_kiocb *req, struct iovec **iovec,
struct iov_iter *iter)
{
const struct io_uring_sqe *sqe = req->submit.sqe;
void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
size_t sqe_len = READ_ONCE(sqe->len);
u8 opcode;
opcode = req->submit.opcode;
if (opcode == IORING_OP_READ_FIXED ||
opcode == IORING_OP_WRITE_FIXED) {
ssize_t ret = io_import_fixed(ctx, rw, sqe, iter);
*iovec = NULL;
return ret;
}
if (!req->submit.has_user)
return -EFAULT;
#ifdef CONFIG_COMPAT
if (ctx->compat)
return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
iovec, iter);
#endif
return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
}
static inline bool io_should_merge(struct async_list *al, struct kiocb *kiocb)
{
if (al->file == kiocb->ki_filp) {
off_t start, end;
/*
* Allow merging if we're anywhere in the range of the same
* page. Generally this happens for sub-page reads or writes,
* and it's beneficial to allow the first worker to bring the
* page in and the piggy backed work can then work on the
* cached page.
*/
start = al->io_start & PAGE_MASK;
end = (al->io_start + al->io_len + PAGE_SIZE - 1) & PAGE_MASK;
if (kiocb->ki_pos >= start && kiocb->ki_pos <= end)
return true;
}
al->file = NULL;
return false;
}
/*
* Make a note of the last file/offset/direction we punted to async
* context. We'll use this information to see if we can piggy back a
* sequential request onto the previous one, if it's still hasn't been
* completed by the async worker.
*/
static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
{
struct async_list *async_list = &req->ctx->pending_async[rw];
struct kiocb *kiocb = &req->rw;
struct file *filp = kiocb->ki_filp;
if (io_should_merge(async_list, kiocb)) {
unsigned long max_bytes;
/* Use 8x RA size as a decent limiter for both reads/writes */
max_bytes = filp->f_ra.ra_pages << (PAGE_SHIFT + 3);
if (!max_bytes)
max_bytes = VM_READAHEAD_PAGES << (PAGE_SHIFT + 3);
/* If max len are exceeded, reset the state */
if (async_list->io_len + len <= max_bytes) {
req->flags |= REQ_F_SEQ_PREV;
async_list->io_len += len;
} else {
async_list->file = NULL;
}
}
/* New file? Reset state. */
if (async_list->file != filp) {
async_list->io_start = kiocb->ki_pos;
async_list->io_len = len;
async_list->file = filp;
}
}
/*
* For files that don't have ->read_iter() and ->write_iter(), handle them
* by looping over ->read() or ->write() manually.
*/
static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
struct iov_iter *iter)
{
ssize_t ret = 0;
/*
* Don't support polled IO through this interface, and we can't
* support non-blocking either. For the latter, this just causes
* the kiocb to be handled from an async context.
*/
if (kiocb->ki_flags & IOCB_HIPRI)
return -EOPNOTSUPP;
if (kiocb->ki_flags & IOCB_NOWAIT)
return -EAGAIN;
while (iov_iter_count(iter)) {
struct iovec iovec;
ssize_t nr;
if (!iov_iter_is_bvec(iter)) {
iovec = iov_iter_iovec(iter);
} else {
/* fixed buffers import bvec */
iovec.iov_base = kmap(iter->bvec->bv_page)
+ iter->iov_offset;
iovec.iov_len = min(iter->count,
iter->bvec->bv_len - iter->iov_offset);
}
if (rw == READ) {
nr = file->f_op->read(file, iovec.iov_base,
iovec.iov_len, &kiocb->ki_pos);
} else {
nr = file->f_op->write(file, iovec.iov_base,
iovec.iov_len, &kiocb->ki_pos);
}
if (iov_iter_is_bvec(iter))
kunmap(iter->bvec->bv_page);
if (nr < 0) {
if (!ret)
ret = nr;
break;
}
ret += nr;
if (nr != iovec.iov_len)
break;
iov_iter_advance(iter, nr);
}
return ret;
}
static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
bool force_nonblock)
{
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
struct kiocb *kiocb = &req->rw;
struct iov_iter iter;
struct file *file;
size_t iov_count;
ssize_t read_size, ret;
ret = io_prep_rw(req, s, force_nonblock);
if (ret)
return ret;
file = kiocb->ki_filp;
if (unlikely(!(file->f_mode & FMODE_READ)))
return -EBADF;
ret = io_import_iovec(req->ctx, READ, req, &iovec, &iter);
if (ret < 0)
return ret;
read_size = ret;
if (req->flags & REQ_F_LINK)
req->result = read_size;
iov_count = iov_iter_count(&iter);
ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
if (!ret) {
ssize_t ret2;
if (file->f_op->read_iter)
ret2 = call_read_iter(file, kiocb, &iter);
else if (req->file->f_op->read)
ret2 = loop_rw_iter(READ, file, kiocb, &iter);
else
ret2 = -EINVAL;
/*
* In case of a short read, punt to async. This can happen
* if we have data partially cached. Alternatively we can
* return the short read, in which case the application will
* need to issue another SQE and wait for it. That SQE will
* need async punt anyway, so it's more efficient to do it
* here.
*/
if (force_nonblock && !(req->flags & REQ_F_NOWAIT) &&
(req->flags & REQ_F_ISREG) &&
ret2 > 0 && ret2 < read_size)
ret2 = -EAGAIN;
/* Catch -EAGAIN return for forced non-blocking submission */
if (!force_nonblock || ret2 != -EAGAIN) {
io_rw_done(kiocb, ret2);
} else {
/*
* If ->needs_lock is true, we're already in async
* context.
*/
if (!s->needs_lock)
io_async_list_note(READ, req, iov_count);
ret = -EAGAIN;
}
}
kfree(iovec);
return ret;
}
static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
bool force_nonblock)
{
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
struct kiocb *kiocb = &req->rw;
struct iov_iter iter;
struct file *file;
size_t iov_count;
ssize_t ret;
ret = io_prep_rw(req, s, force_nonblock);
if (ret)
return ret;
file = kiocb->ki_filp;
if (unlikely(!(file->f_mode & FMODE_WRITE)))
return -EBADF;
ret = io_import_iovec(req->ctx, WRITE, req, &iovec, &iter);
if (ret < 0)
return ret;
if (req->flags & REQ_F_LINK)
req->result = ret;
iov_count = iov_iter_count(&iter);
ret = -EAGAIN;
if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT)) {
/* If ->needs_lock is true, we're already in async context. */
if (!s->needs_lock)
io_async_list_note(WRITE, req, iov_count);
goto out_free;
}
ret = rw_verify_area(WRITE, file, &kiocb->ki_pos, iov_count);
if (!ret) {
ssize_t ret2;
/*
* Open-code file_start_write here to grab freeze protection,
* which will be released by another thread in
* io_complete_rw(). Fool lockdep by telling it the lock got
* released so that it doesn't complain about the held lock when
* we return to userspace.
*/
if (req->flags & REQ_F_ISREG) {
__sb_start_write(file_inode(file)->i_sb,
SB_FREEZE_WRITE, true);
__sb_writers_release(file_inode(file)->i_sb,
SB_FREEZE_WRITE);
}
kiocb->ki_flags |= IOCB_WRITE;
if (!force_nonblock)
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = req->fsize;
if (file->f_op->write_iter)
ret2 = call_write_iter(file, kiocb, &iter);
else if (req->file->f_op->write)
ret2 = loop_rw_iter(WRITE, file, kiocb, &iter);
else
ret2 = -EINVAL;
if (!force_nonblock)
current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
if (!force_nonblock || ret2 != -EAGAIN) {
io_rw_done(kiocb, ret2);
} else {
/*
* If ->needs_lock is true, we're already in async
* context.
*/
if (!s->needs_lock)
io_async_list_note(WRITE, req, iov_count);
ret = -EAGAIN;
}
}
out_free:
kfree(iovec);
return ret;
}
/*
* IORING_OP_NOP just posts a completion event, nothing else.
*/
static int io_nop(struct io_kiocb *req, u64 user_data)
{
struct io_ring_ctx *ctx = req->ctx;
long err = 0;
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
io_cqring_add_event(ctx, user_data, err);
io_put_req(req);
return 0;
}
static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_ring_ctx *ctx = req->ctx;
if (!req->file)
return -EBADF;
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
return -EINVAL;
return 0;
}
static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
bool force_nonblock)
{
loff_t sqe_off = READ_ONCE(sqe->off);
loff_t sqe_len = READ_ONCE(sqe->len);
loff_t end = sqe_off + sqe_len;
unsigned fsync_flags;
int ret;
fsync_flags = READ_ONCE(sqe->fsync_flags);
if (unlikely(fsync_flags & ~IORING_FSYNC_DATASYNC))
return -EINVAL;
ret = io_prep_fsync(req, sqe);
if (ret)
return ret;
/* fsync always requires a blocking context */
if (force_nonblock)
return -EAGAIN;
ret = vfs_fsync_range(req->rw.ki_filp, sqe_off,
end > 0 ? end : LLONG_MAX,
fsync_flags & IORING_FSYNC_DATASYNC);
if (ret < 0 && (req->flags & REQ_F_LINK))
req->flags |= REQ_F_FAIL_LINK;
io_cqring_add_event(req->ctx, sqe->user_data, ret);
io_put_req(req);
return 0;
}
static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_ring_ctx *ctx = req->ctx;
int ret = 0;
if (!req->file)
return -EBADF;
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
return -EINVAL;
return ret;
}
static int io_sync_file_range(struct io_kiocb *req,
const struct io_uring_sqe *sqe,
bool force_nonblock)
{
loff_t sqe_off;
loff_t sqe_len;
unsigned flags;
int ret;
ret = io_prep_sfr(req, sqe);
if (ret)
return ret;
/* sync_file_range always requires a blocking context */
if (force_nonblock)
return -EAGAIN;
sqe_off = READ_ONCE(sqe->off);
sqe_len = READ_ONCE(sqe->len);
flags = READ_ONCE(sqe->sync_range_flags);
ret = sync_file_range(req->rw.ki_filp, sqe_off, sqe_len, flags);
if (ret < 0 && (req->flags & REQ_F_LINK))
req->flags |= REQ_F_FAIL_LINK;
io_cqring_add_event(req->ctx, sqe->user_data, ret);
io_put_req(req);
return 0;
}
#if defined(CONFIG_NET)
static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
bool force_nonblock,
long (*fn)(struct socket *, struct user_msghdr __user *,
unsigned int))
{
struct socket *sock;
int ret;
if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
sock = sock_from_file(req->file, &ret);
if (sock) {
struct user_msghdr __user *msg;
unsigned flags;
flags = READ_ONCE(sqe->msg_flags);
if (flags & MSG_DONTWAIT)
req->flags |= REQ_F_NOWAIT;
else if (force_nonblock)
flags |= MSG_DONTWAIT;
#ifdef CONFIG_COMPAT
if (req->ctx->compat)
flags |= MSG_CMSG_COMPAT;
#endif
msg = (struct user_msghdr __user *) (unsigned long)
READ_ONCE(sqe->addr);
ret = fn(sock, msg, flags);
if (force_nonblock && ret == -EAGAIN)
return ret;
if (ret == -ERESTARTSYS)
ret = -EINTR;
}
io_req_put_fs(req);
io_cqring_add_event(req->ctx, sqe->user_data, ret);
io_put_req(req);
return 0;
}
#endif
static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
bool force_nonblock)
{
#if defined(CONFIG_NET)
return io_send_recvmsg(req, sqe, force_nonblock, __sys_sendmsg_sock);
#else
return -EOPNOTSUPP;
#endif
}
static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
bool force_nonblock)
{
#if defined(CONFIG_NET)
return io_send_recvmsg(req, sqe, force_nonblock, __sys_recvmsg_sock);
#else
return -EOPNOTSUPP;
#endif
}
static void io_poll_remove_one(struct io_kiocb *req)
{
struct io_poll_iocb *poll = &req->poll;
spin_lock(&poll->head->lock);
WRITE_ONCE(poll->canceled, true);
if (!list_empty(&poll->wait.entry)) {
list_del_init(&poll->wait.entry);
io_queue_async_work(req->ctx, req);
}
spin_unlock(&poll->head->lock);
list_del_init(&req->list);
}
static void io_poll_remove_all(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
spin_lock_irq(&ctx->completion_lock);
while (!list_empty(&ctx->cancel_list)) {
req = list_first_entry(&ctx->cancel_list, struct io_kiocb,list);
io_poll_remove_one(req);
}
spin_unlock_irq(&ctx->completion_lock);
}
/*
* Find a running poll command that matches one specified in sqe->addr,
* and remove it if found.
*/
static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_kiocb *poll_req, *next;
int ret = -ENOENT;
if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
sqe->poll_events)
return -EINVAL;
spin_lock_irq(&ctx->completion_lock);
list_for_each_entry_safe(poll_req, next, &ctx->cancel_list, list) {
if (READ_ONCE(sqe->addr) == poll_req->user_data) {
io_poll_remove_one(poll_req);
ret = 0;
break;
}
}
spin_unlock_irq(&ctx->completion_lock);
io_cqring_add_event(req->ctx, sqe->user_data, ret);
io_put_req(req);
return 0;
}
static void io_poll_complete(struct io_ring_ctx *ctx, struct io_kiocb *req,
__poll_t mask)
{
req->poll.done = true;
io_cqring_fill_event(ctx, req->user_data, mangle_poll(mask));
io_commit_cqring(ctx);
}
static void io_poll_complete_work(struct work_struct *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
struct io_poll_iocb *poll = &req->poll;
struct poll_table_struct pt = { ._key = poll->events };
struct io_ring_ctx *ctx = req->ctx;
const struct cred *old_cred;
__poll_t mask = 0;
old_cred = override_creds(ctx->creds);
if (!READ_ONCE(poll->canceled))
mask = vfs_poll(poll->file, &pt) & poll->events;
/*
* Note that ->ki_cancel callers also delete iocb from active_reqs after
* calling ->ki_cancel. We need the ctx_lock roundtrip here to
* synchronize with them. In the cancellation case the list_del_init
* itself is not actually needed, but harmless so we keep it in to
* avoid further branches in the fast path.
*/
spin_lock_irq(&ctx->completion_lock);
if (!mask && !READ_ONCE(poll->canceled)) {
add_wait_queue(poll->head, &poll->wait);
spin_unlock_irq(&ctx->completion_lock);
goto out;
}
list_del_init(&req->list);
io_poll_complete(ctx, req, mask);
spin_unlock_irq(&ctx->completion_lock);
io_cqring_ev_posted(ctx);
io_put_req(req);
out:
revert_creds(old_cred);
}
static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
void *key)
{
struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
wait);
struct io_kiocb *req = container_of(poll, struct io_kiocb, poll);
struct io_ring_ctx *ctx = req->ctx;
__poll_t mask = key_to_poll(key);
unsigned long flags;
/* for instances that support it check for an event match first: */
if (mask && !(mask & poll->events))
return 0;
list_del_init(&poll->wait.entry);
if (mask && spin_trylock_irqsave(&ctx->completion_lock, flags)) {
list_del(&req->list);
io_poll_complete(ctx, req, mask);
spin_unlock_irqrestore(&ctx->completion_lock, flags);
io_cqring_ev_posted(ctx);
io_put_req(req);
} else {
io_queue_async_work(ctx, req);
}
return 1;
}
struct io_poll_table {
struct poll_table_struct pt;
struct io_kiocb *req;
int error;
};
static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
struct poll_table_struct *p)
{
struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);
if (unlikely(pt->req->poll.head)) {
pt->error = -EINVAL;
return;
}
pt->error = 0;
pt->req->poll.head = head;
add_wait_queue(head, &pt->req->poll.wait);
}
static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_poll_iocb *poll = &req->poll;
struct io_ring_ctx *ctx = req->ctx;
struct io_poll_table ipt;
bool cancel = false;
__poll_t mask;
u16 events;
if (req->file->f_op->may_pollfree)
return -EOPNOTSUPP;
if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
return -EINVAL;
if (!poll->file)
return -EBADF;
req->submit.sqe = NULL;
INIT_WORK(&req->work, io_poll_complete_work);
events = READ_ONCE(sqe->poll_events);
poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
poll->head = NULL;
poll->done = false;
poll->canceled = false;
ipt.pt._qproc = io_poll_queue_proc;
ipt.pt._key = poll->events;
ipt.req = req;
ipt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
/* initialized the list so that we can do list_empty checks */
INIT_LIST_HEAD(&poll->wait.entry);
init_waitqueue_func_entry(&poll->wait, io_poll_wake);
INIT_LIST_HEAD(&req->list);
mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
spin_lock_irq(&ctx->completion_lock);
if (likely(poll->head)) {
spin_lock(&poll->head->lock);
if (unlikely(list_empty(&poll->wait.entry))) {
if (ipt.error)
cancel = true;
ipt.error = 0;
mask = 0;
}
if (mask || ipt.error)
list_del_init(&poll->wait.entry);
else if (cancel)
WRITE_ONCE(poll->canceled, true);
else if (!poll->done) /* actually waiting for an event */
list_add_tail(&req->list, &ctx->cancel_list);
spin_unlock(&poll->head->lock);
}
if (mask) { /* no async, we'd stolen it */
ipt.error = 0;
io_poll_complete(ctx, req, mask);
}
spin_unlock_irq(&ctx->completion_lock);
if (mask) {
io_cqring_ev_posted(ctx);
io_put_req(req);
}
return ipt.error;
}
static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
{
struct io_ring_ctx *ctx;
struct io_kiocb *req, *prev;
unsigned long flags;
req = container_of(timer, struct io_kiocb, timeout.timer);
ctx = req->ctx;
atomic_inc(&ctx->cq_timeouts);
spin_lock_irqsave(&ctx->completion_lock, flags);
/*
* Adjust the reqs sequence before the current one because it
* will consume a slot in the cq_ring and the the cq_tail pointer
* will be increased, otherwise other timeout reqs may return in
* advance without waiting for enough wait_nr.
*/
prev = req;
list_for_each_entry_continue_reverse(prev, &ctx->timeout_list, list)
prev->sequence++;
list_del(&req->list);
io_cqring_fill_event(ctx, req->user_data, -ETIME);
io_commit_cqring(ctx);
spin_unlock_irqrestore(&ctx->completion_lock, flags);
io_cqring_ev_posted(ctx);
io_put_req(req);
return HRTIMER_NORESTART;
}
static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
unsigned count;
struct io_ring_ctx *ctx = req->ctx;
struct list_head *entry;
struct timespec64 ts;
unsigned span = 0;
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (sqe->flags || sqe->ioprio || sqe->buf_index || sqe->timeout_flags ||
sqe->len != 1)
return -EINVAL;
if (get_timespec64(&ts, u64_to_user_ptr(sqe->addr)))
return -EFAULT;
req->flags |= REQ_F_TIMEOUT;
/*
* sqe->off holds how many events that need to occur for this
* timeout event to be satisfied. If it isn't set, then this is
* a pure timeout request, sequence isn't used.
*/
count = READ_ONCE(sqe->off);
if (!count) {
req->flags |= REQ_F_TIMEOUT_NOSEQ;
spin_lock_irq(&ctx->completion_lock);
entry = ctx->timeout_list.prev;
goto add;
}
req->sequence = ctx->cached_sq_head + count - 1;
/* reuse it to store the count */
req->submit.sequence = count;
/*
* Insertion sort, ensuring the first entry in the list is always
* the one we need first.
*/
spin_lock_irq(&ctx->completion_lock);
list_for_each_prev(entry, &ctx->timeout_list) {
struct io_kiocb *nxt = list_entry(entry, struct io_kiocb, list);
unsigned nxt_sq_head;
long long tmp, tmp_nxt;
if (nxt->flags & REQ_F_TIMEOUT_NOSEQ)
continue;
/*
* Since cached_sq_head + count - 1 can overflow, use type long
* long to store it.
*/
tmp = (long long)ctx->cached_sq_head + count - 1;
nxt_sq_head = nxt->sequence - nxt->submit.sequence + 1;
tmp_nxt = (long long)nxt_sq_head + nxt->submit.sequence - 1;
/*
* cached_sq_head may overflow, and it will never overflow twice
* once there is some timeout req still be valid.
*/
if (ctx->cached_sq_head < nxt_sq_head)
tmp += UINT_MAX;
if (tmp > tmp_nxt)
break;
/*
* Sequence of reqs after the insert one and itself should
* be adjusted because each timeout req consumes a slot.
*/
span++;
nxt->sequence++;
}
req->sequence -= span;
add:
list_add(&req->list, entry);
spin_unlock_irq(&ctx->completion_lock);
hrtimer_init(&req->timeout.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
req->timeout.timer.function = io_timeout_fn;
hrtimer_start(&req->timeout.timer, timespec64_to_ktime(ts),
HRTIMER_MODE_REL);
return 0;
}
static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req,
struct sqe_submit *s)
{
struct io_uring_sqe *sqe_copy;
if (!io_sequence_defer(ctx, req) && list_empty(&ctx->defer_list))
return 0;
sqe_copy = kmalloc(sizeof(*sqe_copy), GFP_KERNEL);
if (!sqe_copy)
return -EAGAIN;
spin_lock_irq(&ctx->completion_lock);
if (!io_sequence_defer(ctx, req) && list_empty(&ctx->defer_list)) {
spin_unlock_irq(&ctx->completion_lock);
kfree(sqe_copy);
return 0;
}
memcpy(&req->submit, s, sizeof(*s));
memcpy(sqe_copy, s->sqe, sizeof(*sqe_copy));
req->submit.sqe = sqe_copy;
INIT_WORK(&req->work, io_sq_wq_submit_work);
list_add_tail(&req->list, &ctx->defer_list);
spin_unlock_irq(&ctx->completion_lock);
return -EIOCBQUEUED;
}
static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
const struct sqe_submit *s, bool force_nonblock)
{
int ret;
req->user_data = READ_ONCE(s->sqe->user_data);
if (unlikely(s->index >= ctx->sq_entries))
return -EINVAL;
switch (req->submit.opcode) {
case IORING_OP_NOP:
ret = io_nop(req, req->user_data);
break;
case IORING_OP_READV:
if (unlikely(s->sqe->buf_index))
return -EINVAL;
ret = io_read(req, s, force_nonblock);
break;
case IORING_OP_WRITEV:
if (unlikely(s->sqe->buf_index))
return -EINVAL;
ret = io_write(req, s, force_nonblock);
break;
case IORING_OP_READ_FIXED:
ret = io_read(req, s, force_nonblock);
break;
case IORING_OP_WRITE_FIXED:
ret = io_write(req, s, force_nonblock);
break;
case IORING_OP_FSYNC:
ret = io_fsync(req, s->sqe, force_nonblock);
break;
case IORING_OP_POLL_ADD:
ret = io_poll_add(req, s->sqe);
break;
case IORING_OP_POLL_REMOVE:
ret = io_poll_remove(req, s->sqe);
break;
case IORING_OP_SYNC_FILE_RANGE:
ret = io_sync_file_range(req, s->sqe, force_nonblock);
break;
case IORING_OP_SENDMSG:
ret = io_sendmsg(req, s->sqe, force_nonblock);
break;
case IORING_OP_RECVMSG:
ret = io_recvmsg(req, s->sqe, force_nonblock);
break;
case IORING_OP_TIMEOUT:
ret = io_timeout(req, s->sqe);
break;
default:
ret = -EINVAL;
break;
}
if (ret)
return ret;
if (ctx->flags & IORING_SETUP_IOPOLL) {
if (req->result == -EAGAIN)
return -EAGAIN;
/* workqueue context doesn't hold uring_lock, grab it now */
if (s->needs_lock)
mutex_lock(&ctx->uring_lock);
io_iopoll_req_issued(req);
if (s->needs_lock)
mutex_unlock(&ctx->uring_lock);
}
return 0;
}
static struct async_list *io_async_list_from_req(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
switch (req->submit.opcode) {
case IORING_OP_READV:
case IORING_OP_READ_FIXED:
return &ctx->pending_async[READ];
case IORING_OP_WRITEV:
case IORING_OP_WRITE_FIXED:
return &ctx->pending_async[WRITE];
default:
return NULL;
}
}
static inline bool io_req_needs_user(struct io_kiocb *req)
{
return !(req->submit.opcode == IORING_OP_READ_FIXED ||
req->submit.opcode == IORING_OP_WRITE_FIXED);
}
static void io_sq_wq_submit_work(struct work_struct *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
struct fs_struct *old_fs_struct = current->fs;
struct io_ring_ctx *ctx = req->ctx;
struct mm_struct *cur_mm = NULL;
struct async_list *async_list;
const struct cred *old_cred;
LIST_HEAD(req_list);
mm_segment_t old_fs;
int ret;
old_cred = override_creds(ctx->creds);
async_list = io_async_list_from_req(ctx, req);
allow_kernel_signal(SIGINT);
restart:
do {
struct sqe_submit *s = &req->submit;
const struct io_uring_sqe *sqe = s->sqe;
unsigned int flags = req->flags;
/* Ensure we clear previously set non-block flag */
req->rw.ki_flags &= ~IOCB_NOWAIT;
if ((req->fs && req->fs != current->fs) ||
(!req->fs && current->fs != old_fs_struct)) {
task_lock(current);
if (req->fs)
current->fs = req->fs;
else
current->fs = old_fs_struct;
task_unlock(current);
}
ret = 0;
if (io_req_needs_user(req) && !cur_mm) {
if (!mmget_not_zero(ctx->sqo_mm)) {
ret = -EFAULT;
goto end_req;
} else {
cur_mm = ctx->sqo_mm;
use_mm(cur_mm);
old_fs = get_fs();
set_fs(USER_DS);
}
}
if (!ret) {
req->work_task = current;
/*
* Pairs with the smp_store_mb() (B) in
* io_cancel_async_work().
*/
smp_mb(); /* A */
if (req->flags & REQ_F_CANCEL) {
ret = -ECANCELED;
goto end_req;
}
s->has_user = cur_mm != NULL;
s->needs_lock = true;
do {
ret = __io_submit_sqe(ctx, req, s, false);
/*
* We can get EAGAIN for polled IO even though
* we're forcing a sync submission from here,
* since we can't wait for request slots on the
* block side.
*/
if (ret != -EAGAIN)
break;
cond_resched();
} while (1);
}
end_req:
spin_lock_irq(&ctx->task_lock);
list_del_init(&req->task_list);
spin_unlock_irq(&ctx->task_lock);
/* drop submission reference */
io_put_req(req);
if (ret) {
io_cqring_add_event(ctx, sqe->user_data, ret);
io_put_req(req);
}
/* async context always use a copy of the sqe */
kfree(sqe);
/* req from defer and link list needn't decrease async cnt */
if (flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE))
goto out;
if (!async_list)
break;
if (!list_empty(&req_list)) {
req = list_first_entry(&req_list, struct io_kiocb,
list);
list_del(&req->list);
continue;
}
if (list_empty(&async_list->list))
break;
req = NULL;
spin_lock(&async_list->lock);
if (list_empty(&async_list->list)) {
spin_unlock(&async_list->lock);
break;
}
list_splice_init(&async_list->list, &req_list);
spin_unlock(&async_list->lock);
req = list_first_entry(&req_list, struct io_kiocb, list);
list_del(&req->list);
} while (req);
/*
* Rare case of racing with a submitter. If we find the count has
* dropped to zero AND we have pending work items, then restart
* the processing. This is a tiny race window.
*/
if (async_list) {
ret = atomic_dec_return(&async_list->cnt);
while (!ret && !list_empty(&async_list->list)) {
spin_lock(&async_list->lock);
atomic_inc(&async_list->cnt);
list_splice_init(&async_list->list, &req_list);
spin_unlock(&async_list->lock);
if (!list_empty(&req_list)) {
req = list_first_entry(&req_list,
struct io_kiocb, list);
list_del(&req->list);
goto restart;
}
ret = atomic_dec_return(&async_list->cnt);
}
}
out:
disallow_signal(SIGINT);
if (cur_mm) {
set_fs(old_fs);
unuse_mm(cur_mm);
mmput(cur_mm);
}
revert_creds(old_cred);
if (old_fs_struct != current->fs) {
task_lock(current);
current->fs = old_fs_struct;
task_unlock(current);
}
}
/*
* See if we can piggy back onto previously submitted work, that is still
* running. We currently only allow this if the new request is sequential
* to the previous one we punted.
*/
static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
{
bool ret;
if (!list)
return false;
if (!(req->flags & REQ_F_SEQ_PREV))
return false;
if (!atomic_read(&list->cnt))
return false;
ret = true;
spin_lock(&list->lock);
list_add_tail(&req->list, &list->list);
/*
* Ensure we see a simultaneous modification from io_sq_wq_submit_work()
*/
smp_mb();
if (!atomic_read(&list->cnt)) {
list_del_init(&req->list);
ret = false;
}
if (ret) {
struct io_ring_ctx *ctx = req->ctx;
req->files = current->files;
spin_lock_irq(&ctx->task_lock);
list_add(&req->task_list, &ctx->task_list);
req->work_task = NULL;
spin_unlock_irq(&ctx->task_lock);
}
spin_unlock(&list->lock);
return ret;
}
static bool io_op_needs_file(struct io_kiocb *req)
{
switch (req->submit.opcode) {
case IORING_OP_NOP:
case IORING_OP_POLL_REMOVE:
case IORING_OP_TIMEOUT:
return false;
default:
return true;
}
}
static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
struct io_submit_state *state, struct io_kiocb *req)
{
unsigned flags;
int fd;
flags = READ_ONCE(s->sqe->flags);
fd = READ_ONCE(s->sqe->fd);
if (flags & IOSQE_IO_DRAIN)
req->flags |= REQ_F_IO_DRAIN;
/*
* All io need record the previous position, if LINK vs DARIN,
* it can be used to mark the position of the first IO in the
* link list.
*/
req->sequence = s->sequence;
if (!io_op_needs_file(req))
return 0;
if (flags & IOSQE_FIXED_FILE) {
if (unlikely(!ctx->user_files ||
(unsigned) fd >= ctx->nr_user_files))
return -EBADF;
req->file = ctx->user_files[fd];
req->flags |= REQ_F_FIXED_FILE;
} else {
if (s->needs_fixed_file)
return -EBADF;
req->file = io_file_get(state, fd);
if (unlikely(!req->file))
return -EBADF;
}
return 0;
}
static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
struct sqe_submit *s)
{
int ret;
ret = __io_submit_sqe(ctx, req, s, true);
/*
* We async punt it if the file wasn't marked NOWAIT, or if the file
* doesn't support non-blocking read/write attempts
*/
if (ret == -EAGAIN && (!(req->flags & REQ_F_NOWAIT) ||
(req->flags & REQ_F_MUST_PUNT))) {
struct io_uring_sqe *sqe_copy;
sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
if (sqe_copy) {
struct async_list *list;
s->sqe = sqe_copy;
memcpy(&req->submit, s, sizeof(*s));
list = io_async_list_from_req(ctx, req);
if (!io_add_to_prev_work(list, req)) {
if (list)
atomic_inc(&list->cnt);
INIT_WORK(&req->work, io_sq_wq_submit_work);
io_queue_async_work(ctx, req);
}
/*
* Queued up for async execution, worker will release
* submit reference when the iocb is actually submitted.
*/
return 0;
}
}
/* drop submission reference */
io_put_req(req);
/* and drop final reference, if we failed */
if (ret) {
io_cqring_add_event(ctx, req->user_data, ret);
if (req->flags & REQ_F_LINK)
req->flags |= REQ_F_FAIL_LINK;
io_put_req(req);
}
return ret;
}
static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
struct sqe_submit *s)
{
int ret;
ret = io_req_defer(ctx, req, s);
if (ret) {
if (ret != -EIOCBQUEUED) {
io_free_req(req);
io_cqring_add_event(ctx, s->sqe->user_data, ret);
}
return 0;
}
return __io_queue_sqe(ctx, req, s);
}
static int io_queue_link_head(struct io_ring_ctx *ctx, struct io_kiocb *req,
struct sqe_submit *s, struct io_kiocb *shadow)
{
int ret;
int need_submit = false;
if (!shadow)
return io_queue_sqe(ctx, req, s);
/*
* Mark the first IO in link list as DRAIN, let all the following
* IOs enter the defer list. all IO needs to be completed before link
* list.
*/
req->flags |= REQ_F_IO_DRAIN;
ret = io_req_defer(ctx, req, s);
if (ret) {
if (ret != -EIOCBQUEUED) {
io_free_req(req);
__io_free_req(shadow);
io_cqring_add_event(ctx, s->sqe->user_data, ret);
return 0;
}
} else {
/*
* If ret == 0 means that all IOs in front of link io are
* running done. let's queue link head.
*/
need_submit = true;
}
/* Insert shadow req to defer_list, blocking next IOs */
spin_lock_irq(&ctx->completion_lock);
list_add_tail(&shadow->list, &ctx->defer_list);
spin_unlock_irq(&ctx->completion_lock);
if (need_submit)
return __io_queue_sqe(ctx, req, s);
return 0;
}
#define SQE_VALID_FLAGS (IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK)
static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
struct io_submit_state *state, struct io_kiocb **link)
{
struct io_uring_sqe *sqe_copy;
struct io_kiocb *req;
int ret;
/* enforce forwards compatibility on users */
if (unlikely(s->sqe->flags & ~SQE_VALID_FLAGS)) {
ret = -EINVAL;
goto err;
}
req = io_get_req(ctx, state);
if (unlikely(!req)) {
ret = -EAGAIN;
goto err;
}
memcpy(&req->submit, s, sizeof(*s));
ret = io_req_set_file(ctx, s, state, req);
if (unlikely(ret)) {
err_req:
io_free_req(req);
err:
io_cqring_add_event(ctx, s->sqe->user_data, ret);
return;
}
req->user_data = s->sqe->user_data;
#if defined(CONFIG_NET)
switch (req->submit.opcode) {
case IORING_OP_SENDMSG:
case IORING_OP_RECVMSG:
spin_lock(&current->fs->lock);
if (!current->fs->in_exec) {
req->fs = current->fs;
req->fs->users++;
}
spin_unlock(&current->fs->lock);
if (!req->fs) {
ret = -EAGAIN;
goto err_req;
}
}
#endif
/*
* If we already have a head request, queue this one for async
* submittal once the head completes. If we don't have a head but
* IOSQE_IO_LINK is set in the sqe, start a new head. This one will be
* submitted sync once the chain is complete. If none of those
* conditions are true (normal request), then just queue it.
*/
if (*link) {
struct io_kiocb *prev = *link;
sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
if (!sqe_copy) {
ret = -EAGAIN;
goto err_req;
}
s->sqe = sqe_copy;
memcpy(&req->submit, s, sizeof(*s));
list_add_tail(&req->list, &prev->link_list);
} else if (s->sqe->flags & IOSQE_IO_LINK) {
req->flags |= REQ_F_LINK;
memcpy(&req->submit, s, sizeof(*s));
INIT_LIST_HEAD(&req->link_list);
*link = req;
} else {
io_queue_sqe(ctx, req, s);
}
}
/*
* Batched submission is done, ensure local IO is flushed out.
*/
static void io_submit_state_end(struct io_submit_state *state)
{
blk_finish_plug(&state->plug);
io_file_put(state);
if (state->free_reqs)
kmem_cache_free_bulk(req_cachep, state->free_reqs,
&state->reqs[state->cur_req]);
}
/*
* Start submission side cache.
*/
static void io_submit_state_start(struct io_submit_state *state,
struct io_ring_ctx *ctx, unsigned max_ios)
{
blk_start_plug(&state->plug);
state->free_reqs = 0;
state->file = NULL;
state->ios_left = max_ios;
}
static void io_commit_sqring(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
if (ctx->cached_sq_head != READ_ONCE(rings->sq.head)) {
/*
* Ensure any loads from the SQEs are done at this point,
* since once we write the new head, the application could
* write new data to them.
*/
smp_store_release(&rings->sq.head, ctx->cached_sq_head);
}
}
/*
* Fetch an sqe, if one is available. Note that s->sqe will point to memory
* that is mapped by userspace. This means that care needs to be taken to
* ensure that reads are stable, as we cannot rely on userspace always
* being a good citizen. If members of the sqe are validated and then later
* used, it's important that those reads are done through READ_ONCE() to
* prevent a re-load down the line.
*/
static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
{
struct io_rings *rings = ctx->rings;
u32 *sq_array = ctx->sq_array;
unsigned head;
/*
* The cached sq head (or cq tail) serves two purposes:
*
* 1) allows us to batch the cost of updating the user visible
* head updates.
* 2) allows the kernel side to track the head on its own, even
* though the application is the one updating it.
*/
head = ctx->cached_sq_head;
/* make sure SQ entry isn't read before tail */
if (head == smp_load_acquire(&rings->sq.tail))
return false;
head = READ_ONCE(sq_array[head & ctx->sq_mask]);
if (head < ctx->sq_entries) {
s->index = head;
s->sqe = &ctx->sq_sqes[head];
s->opcode = READ_ONCE(s->sqe->opcode);
s->sequence = ctx->cached_sq_head;
ctx->cached_sq_head++;
return true;
}
/* drop invalid entries */
ctx->cached_sq_head++;
ctx->cached_sq_dropped++;
WRITE_ONCE(rings->sq_dropped, ctx->cached_sq_dropped);
return false;
}
static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
bool has_user, bool mm_fault)
{
struct io_submit_state state, *statep = NULL;
struct io_kiocb *link = NULL;
struct io_kiocb *shadow_req = NULL;
bool prev_was_link = false;
int i, submitted = 0;
if (nr > IO_PLUG_THRESHOLD) {
io_submit_state_start(&state, ctx, nr);
statep = &state;
}
for (i = 0; i < nr; i++) {
struct sqe_submit s;
if (!io_get_sqring(ctx, &s))
break;
/*
* If previous wasn't linked and we have a linked command,
* that's the end of the chain. Submit the previous link.
*/
if (!prev_was_link && link) {
io_queue_link_head(ctx, link, &link->submit, shadow_req);
link = NULL;
shadow_req = NULL;
}
prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
if (!shadow_req) {
shadow_req = io_get_req(ctx, NULL);
if (unlikely(!shadow_req))
goto out;
shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
refcount_dec(&shadow_req->refs);
}
shadow_req->sequence = s.sequence;
}
out:
if (unlikely(mm_fault)) {
io_cqring_add_event(ctx, s.sqe->user_data,
-EFAULT);
} else {
s.has_user = has_user;
s.needs_lock = true;
s.needs_fixed_file = true;
io_submit_sqe(ctx, &s, statep, &link);
submitted++;
}
}
if (link)
io_queue_link_head(ctx, link, &link->submit, shadow_req);
if (statep)
io_submit_state_end(&state);
return submitted;
}
static int io_sq_thread(void *data)
{
struct io_ring_ctx *ctx = data;
struct mm_struct *cur_mm = NULL;
const struct cred *old_cred;
mm_segment_t old_fs;
DEFINE_WAIT(wait);
unsigned inflight;
unsigned long timeout;
complete(&ctx->sqo_thread_started);
old_fs = get_fs();
set_fs(USER_DS);
old_cred = override_creds(ctx->creds);
timeout = inflight = 0;
while (!kthread_should_park()) {
bool mm_fault = false;
unsigned int to_submit;
if (inflight) {
unsigned nr_events = 0;
if (ctx->flags & IORING_SETUP_IOPOLL) {
/*
* inflight is the count of the maximum possible
* entries we submitted, but it can be smaller
* if we dropped some of them. If we don't have
* poll entries available, then we know that we
* have nothing left to poll for. Reset the
* inflight count to zero in that case.
*/
mutex_lock(&ctx->uring_lock);
if (!list_empty(&ctx->poll_list))
io_iopoll_getevents(ctx, &nr_events, 0);
else
inflight = 0;
mutex_unlock(&ctx->uring_lock);
} else {
/*
* Normal IO, just pretend everything completed.
* We don't have to poll completions for that.
*/
nr_events = inflight;
}
inflight -= nr_events;
if (!inflight)
timeout = jiffies + ctx->sq_thread_idle;
}
to_submit = io_sqring_entries(ctx);
if (!to_submit) {
/*
* Drop cur_mm before scheduling, we can't hold it for
* long periods (or over schedule()). Do this before
* adding ourselves to the waitqueue, as the unuse/drop
* may sleep.
*/
if (cur_mm) {
unuse_mm(cur_mm);
mmput(cur_mm);
cur_mm = NULL;
}
/*
* We're polling. If we're within the defined idle
* period, then let us spin without work before going
* to sleep.
*/
if (inflight || !time_after(jiffies, timeout)) {
cond_resched();
continue;
}
prepare_to_wait(&ctx->sqo_wait, &wait,
TASK_INTERRUPTIBLE);
/* Tell userspace we may need a wakeup call */
ctx->rings->sq_flags |= IORING_SQ_NEED_WAKEUP;
/* make sure to read SQ tail after writing flags */
smp_mb();
to_submit = io_sqring_entries(ctx);
if (!to_submit) {
if (kthread_should_park()) {
finish_wait(&ctx->sqo_wait, &wait);
break;
}
if (signal_pending(current))
flush_signals(current);
schedule();
finish_wait(&ctx->sqo_wait, &wait);
ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
continue;
}
finish_wait(&ctx->sqo_wait, &wait);
ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
}
/* Unless all new commands are FIXED regions, grab mm */
if (!cur_mm) {
mm_fault = !mmget_not_zero(ctx->sqo_mm);
if (!mm_fault) {
use_mm(ctx->sqo_mm);
cur_mm = ctx->sqo_mm;
}
}
to_submit = min(to_submit, ctx->sq_entries);
inflight += io_submit_sqes(ctx, to_submit, cur_mm != NULL,
mm_fault);
/* Commit SQ ring head once we've consumed all SQEs */
io_commit_sqring(ctx);
}
set_fs(old_fs);
if (cur_mm) {
unuse_mm(cur_mm);
mmput(cur_mm);
}
revert_creds(old_cred);
kthread_parkme();
return 0;
}
static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
{
struct io_submit_state state, *statep = NULL;
struct io_kiocb *link = NULL;
struct io_kiocb *shadow_req = NULL;
bool prev_was_link = false;
int i, submit = 0;
if (to_submit > IO_PLUG_THRESHOLD) {
io_submit_state_start(&state, ctx, to_submit);
statep = &state;
}
for (i = 0; i < to_submit; i++) {
struct sqe_submit s;
if (!io_get_sqring(ctx, &s))
break;
/*
* If previous wasn't linked and we have a linked command,
* that's the end of the chain. Submit the previous link.
*/
if (!prev_was_link && link) {
io_queue_link_head(ctx, link, &link->submit, shadow_req);
link = NULL;
shadow_req = NULL;
}
prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
if (!shadow_req) {
shadow_req = io_get_req(ctx, NULL);
if (unlikely(!shadow_req))
goto out;
shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
refcount_dec(&shadow_req->refs);
}
shadow_req->sequence = s.sequence;
}
out:
s.has_user = true;
s.needs_lock = false;
s.needs_fixed_file = false;
submit++;
io_submit_sqe(ctx, &s, statep, &link);
}
if (link)
io_queue_link_head(ctx, link, &link->submit, shadow_req);
if (statep)
io_submit_state_end(statep);
io_commit_sqring(ctx);
return submit;
}
struct io_wait_queue {
struct wait_queue_entry wq;
struct io_ring_ctx *ctx;
unsigned to_wait;
unsigned nr_timeouts;
};
static inline bool io_should_wake(struct io_wait_queue *iowq)
{
struct io_ring_ctx *ctx = iowq->ctx;
/*
* Wake up if we have enough events, or if a timeout occured since we
* started waiting. For timeouts, we always want to return to userspace,
* regardless of event count.
*/
return io_cqring_events(ctx->rings) >= iowq->to_wait ||
atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
}
static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
int wake_flags, void *key)
{
struct io_wait_queue *iowq = container_of(curr, struct io_wait_queue,
wq);
if (!io_should_wake(iowq))
return -1;
return autoremove_wake_function(curr, mode, wake_flags, key);
}
/*
* Wait until events become available, if we don't already have some. The
* application must reap them itself, as they reside on the shared cq ring.
*/
static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
const sigset_t __user *sig, size_t sigsz)
{
struct io_wait_queue iowq = {
.wq = {
.private = current,
.func = io_wake_function,
.entry = LIST_HEAD_INIT(iowq.wq.entry),
},
.ctx = ctx,
.to_wait = min_events,
};
struct io_rings *rings = ctx->rings;
int ret;
if (io_cqring_events(rings) >= min_events)
return 0;
if (sig) {
#ifdef CONFIG_COMPAT
if (in_compat_syscall())
ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
sigsz);
else
#endif
ret = set_user_sigmask(sig, sigsz);
if (ret)
return ret;
}
ret = 0;
iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
do {
prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
TASK_INTERRUPTIBLE);
if (io_should_wake(&iowq))
break;
schedule();
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
} while (1);
finish_wait(&ctx->wait, &iowq.wq);
restore_saved_sigmask_unless(ret == -ERESTARTSYS);
if (ret == -ERESTARTSYS)
ret = -EINTR;
return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
}
static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
{
#if defined(CONFIG_UNIX)
if (ctx->ring_sock) {
struct sock *sock = ctx->ring_sock->sk;
struct sk_buff *skb;
while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
kfree_skb(skb);
}
#else
int i;
for (i = 0; i < ctx->nr_user_files; i++)
fput(ctx->user_files[i]);
#endif
}
static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
{
if (!ctx->user_files)
return -ENXIO;
__io_sqe_files_unregister(ctx);
kfree(ctx->user_files);
ctx->user_files = NULL;
ctx->nr_user_files = 0;
return 0;
}
static void io_sq_thread_stop(struct io_ring_ctx *ctx)
{
if (ctx->sqo_thread) {
wait_for_completion(&ctx->sqo_thread_started);
/*
* The park is a bit of a work-around, without it we get
* warning spews on shutdown with SQPOLL set and affinity
* set to a single CPU.
*/
kthread_park(ctx->sqo_thread);
kthread_stop(ctx->sqo_thread);
ctx->sqo_thread = NULL;
}
}
static void io_finish_async(struct io_ring_ctx *ctx)
{
int i;
io_sq_thread_stop(ctx);
for (i = 0; i < ARRAY_SIZE(ctx->sqo_wq); i++) {
if (ctx->sqo_wq[i]) {
destroy_workqueue(ctx->sqo_wq[i]);
ctx->sqo_wq[i] = NULL;
}
}
}
#if defined(CONFIG_UNIX)
static void io_destruct_skb(struct sk_buff *skb)
{
struct io_ring_ctx *ctx = skb->sk->sk_user_data;
int i;
for (i = 0; i < ARRAY_SIZE(ctx->sqo_wq); i++)
if (ctx->sqo_wq[i])
flush_workqueue(ctx->sqo_wq[i]);
unix_destruct_scm(skb);
}
/*
* Ensure the UNIX gc is aware of our file set, so we are certain that
* the io_uring can be safely unregistered on process exit, even if we have
* loops in the file referencing.
*/
static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
{
struct sock *sk = ctx->ring_sock->sk;
struct scm_fp_list *fpl;
struct sk_buff *skb;
int i;
fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
if (!fpl)
return -ENOMEM;
skb = alloc_skb(0, GFP_KERNEL);
if (!skb) {
kfree(fpl);
return -ENOMEM;
}
skb->sk = sk;
skb->scm_io_uring = 1;
skb->destructor = io_destruct_skb;
fpl->user = get_uid(ctx->user);
for (i = 0; i < nr; i++) {
fpl->fp[i] = get_file(ctx->user_files[i + offset]);
unix_inflight(fpl->user, fpl->fp[i]);
}
fpl->max = fpl->count = nr;
UNIXCB(skb).fp = fpl;
refcount_add(skb->truesize, &sk->sk_wmem_alloc);
skb_queue_head(&sk->sk_receive_queue, skb);
for (i = 0; i < nr; i++)
fput(fpl->fp[i]);
return 0;
}
/*
* If UNIX sockets are enabled, fd passing can cause a reference cycle which
* causes regular reference counting to break down. We rely on the UNIX
* garbage collection to take care of this problem for us.
*/
static int io_sqe_files_scm(struct io_ring_ctx *ctx)
{
unsigned left, total;
int ret = 0;
total = 0;
left = ctx->nr_user_files;
while (left) {
unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
ret = __io_sqe_files_scm(ctx, this_files, total);
if (ret)
break;
left -= this_files;
total += this_files;
}
if (!ret)
return 0;
while (total < ctx->nr_user_files) {
fput(ctx->user_files[total]);
total++;
}
return ret;
}
#else
static int io_sqe_files_scm(struct io_ring_ctx *ctx)
{
return 0;
}
#endif
static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
unsigned nr_args)
{
__s32 __user *fds = (__s32 __user *) arg;
int fd, ret = 0;
unsigned i;
if (ctx->user_files)
return -EBUSY;
if (!nr_args)
return -EINVAL;
if (nr_args > IORING_MAX_FIXED_FILES)
return -EMFILE;
ctx->user_files = kcalloc(nr_args, sizeof(struct file *), GFP_KERNEL);
if (!ctx->user_files)
return -ENOMEM;
for (i = 0; i < nr_args; i++) {
ret = -EFAULT;
if (copy_from_user(&fd, &fds[i], sizeof(fd)))
break;
ctx->user_files[i] = fget(fd);
ret = -EBADF;
if (!ctx->user_files[i])
break;
/*
* Don't allow io_uring instances to be registered. If UNIX
* isn't enabled, then this causes a reference cycle and this
* instance can never get freed. If UNIX is enabled we'll
* handle it just fine, but there's still no point in allowing
* a ring fd as it doesn't support regular read/write anyway.
*/
if (ctx->user_files[i]->f_op == &io_uring_fops) {
fput(ctx->user_files[i]);
break;
}
ctx->nr_user_files++;
ret = 0;
}
if (ret) {
for (i = 0; i < ctx->nr_user_files; i++)
fput(ctx->user_files[i]);
kfree(ctx->user_files);
ctx->user_files = NULL;
ctx->nr_user_files = 0;
return ret;
}
ret = io_sqe_files_scm(ctx);
if (ret)
io_sqe_files_unregister(ctx);
return ret;
}
static int io_sq_offload_start(struct io_ring_ctx *ctx,
struct io_uring_params *p)
{
int ret;
mmgrab(current->mm);
ctx->sqo_mm = current->mm;
if (ctx->flags & IORING_SETUP_SQPOLL) {
ret = -EPERM;
if (!capable(CAP_SYS_ADMIN))
goto err;
ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
if (!ctx->sq_thread_idle)
ctx->sq_thread_idle = HZ;
if (p->flags & IORING_SETUP_SQ_AFF) {
int cpu = p->sq_thread_cpu;
ret = -EINVAL;
if (cpu >= nr_cpu_ids)
goto err;
if (!cpu_online(cpu))
goto err;
ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread,
ctx, cpu,
"io_uring-sq");
} else {
ctx->sqo_thread = kthread_create(io_sq_thread, ctx,
"io_uring-sq");
}
if (IS_ERR(ctx->sqo_thread)) {
ret = PTR_ERR(ctx->sqo_thread);
ctx->sqo_thread = NULL;
goto err;
}
wake_up_process(ctx->sqo_thread);
} else if (p->flags & IORING_SETUP_SQ_AFF) {
/* Can't have SQ_AFF without SQPOLL */
ret = -EINVAL;
goto err;
}
/* Do QD, or 2 * CPUS, whatever is smallest */
ctx->sqo_wq[0] = alloc_workqueue("io_ring-wq",
WQ_UNBOUND | WQ_FREEZABLE,
min(ctx->sq_entries - 1, 2 * num_online_cpus()));
if (!ctx->sqo_wq[0]) {
ret = -ENOMEM;
goto err;
}
/*
* This is for buffered writes, where we want to limit the parallelism
* due to file locking in file systems. As "normal" buffered writes
* should parellelize on writeout quite nicely, limit us to having 2
* pending. This avoids massive contention on the inode when doing
* buffered async writes.
*/
ctx->sqo_wq[1] = alloc_workqueue("io_ring-write-wq",
WQ_UNBOUND | WQ_FREEZABLE, 2);
if (!ctx->sqo_wq[1]) {
ret = -ENOMEM;
goto err;
}
return 0;
err:
io_finish_async(ctx);
mmdrop(ctx->sqo_mm);
ctx->sqo_mm = NULL;
return ret;
}
static void io_unaccount_mem(struct user_struct *user, unsigned long nr_pages)
{
atomic_long_sub(nr_pages, &user->locked_vm);
}
static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
{
unsigned long page_limit, cur_pages, new_pages;
/* Don't allow more pages than we can safely lock */
page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
do {
cur_pages = atomic_long_read(&user->locked_vm);
new_pages = cur_pages + nr_pages;
if (new_pages > page_limit)
return -ENOMEM;
} while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
new_pages) != cur_pages);
return 0;
}
static void io_mem_free(void *ptr)
{
struct page *page;
if (!ptr)
return;
page = virt_to_head_page(ptr);
if (put_page_testzero(page))
free_compound_page(page);
}
static void *io_mem_alloc(size_t size)
{
gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP |
__GFP_NORETRY;
return (void *) __get_free_pages(gfp_flags, get_order(size));
}
static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
size_t *sq_offset)
{
struct io_rings *rings;
size_t off, sq_array_size;
off = struct_size(rings, cqes, cq_entries);
if (off == SIZE_MAX)
return SIZE_MAX;
#ifdef CONFIG_SMP
off = ALIGN(off, SMP_CACHE_BYTES);
if (off == 0)
return SIZE_MAX;
#endif
if (sq_offset)
*sq_offset = off;
sq_array_size = array_size(sizeof(u32), sq_entries);
if (sq_array_size == SIZE_MAX)
return SIZE_MAX;
if (check_add_overflow(off, sq_array_size, &off))
return SIZE_MAX;
return off;
}
static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
{
size_t pages;
pages = (size_t)1 << get_order(
rings_size(sq_entries, cq_entries, NULL));
pages += (size_t)1 << get_order(
array_size(sizeof(struct io_uring_sqe), sq_entries));
return pages;
}
static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
{
int i, j;
if (!ctx->user_bufs)
return -ENXIO;
for (i = 0; i < ctx->nr_user_bufs; i++) {
struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
for (j = 0; j < imu->nr_bvecs; j++)
put_user_page(imu->bvec[j].bv_page);
if (ctx->account_mem)
io_unaccount_mem(ctx->user, imu->nr_bvecs);
kvfree(imu->bvec);
imu->nr_bvecs = 0;
}
kfree(ctx->user_bufs);
ctx->user_bufs = NULL;
ctx->nr_user_bufs = 0;
return 0;
}
static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
void __user *arg, unsigned index)
{
struct iovec __user *src;
#ifdef CONFIG_COMPAT
if (ctx->compat) {
struct compat_iovec __user *ciovs;
struct compat_iovec ciov;
ciovs = (struct compat_iovec __user *) arg;
if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
return -EFAULT;
dst->iov_base = (void __user *) (unsigned long) ciov.iov_base;
dst->iov_len = ciov.iov_len;
return 0;
}
#endif
src = (struct iovec __user *) arg;
if (copy_from_user(dst, &src[index], sizeof(*dst)))
return -EFAULT;
return 0;
}
static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
unsigned nr_args)
{
struct vm_area_struct **vmas = NULL;
struct page **pages = NULL;
int i, j, got_pages = 0;
int ret = -EINVAL;
if (ctx->user_bufs)
return -EBUSY;
if (!nr_args || nr_args > UIO_MAXIOV)
return -EINVAL;
ctx->user_bufs = kcalloc(nr_args, sizeof(struct io_mapped_ubuf),
GFP_KERNEL);
if (!ctx->user_bufs)
return -ENOMEM;
for (i = 0; i < nr_args; i++) {
struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
unsigned long off, start, end, ubuf;
int pret, nr_pages;
struct iovec iov;
size_t size;
ret = io_copy_iov(ctx, &iov, arg, i);
if (ret)
goto err;
/*
* Don't impose further limits on the size and buffer
* constraints here, we'll -EINVAL later when IO is
* submitted if they are wrong.
*/
ret = -EFAULT;
if (!iov.iov_base || !iov.iov_len)
goto err;
/* arbitrary limit, but we need something */
if (iov.iov_len > SZ_1G)
goto err;
ubuf = (unsigned long) iov.iov_base;
end = (ubuf + iov.iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
start = ubuf >> PAGE_SHIFT;
nr_pages = end - start;
if (ctx->account_mem) {
ret = io_account_mem(ctx->user, nr_pages);
if (ret)
goto err;
}
ret = 0;
if (!pages || nr_pages > got_pages) {
kvfree(vmas);
kvfree(pages);
pages = kvmalloc_array(nr_pages, sizeof(struct page *),
GFP_KERNEL);
vmas = kvmalloc_array(nr_pages,
sizeof(struct vm_area_struct *),
GFP_KERNEL);
if (!pages || !vmas) {
ret = -ENOMEM;
if (ctx->account_mem)
io_unaccount_mem(ctx->user, nr_pages);
goto err;
}
got_pages = nr_pages;
}
imu->bvec = kvmalloc_array(nr_pages, sizeof(struct bio_vec),
GFP_KERNEL);
ret = -ENOMEM;
if (!imu->bvec) {
if (ctx->account_mem)
io_unaccount_mem(ctx->user, nr_pages);
goto err;
}
ret = 0;
down_read(&current->mm->mmap_sem);
pret = get_user_pages(ubuf, nr_pages,
FOLL_WRITE | FOLL_LONGTERM,
pages, vmas);
if (pret == nr_pages) {
/* don't support file backed memory */
for (j = 0; j < nr_pages; j++) {
struct vm_area_struct *vma = vmas[j];
if (vma->vm_file &&
!is_file_hugepages(vma->vm_file)) {
ret = -EOPNOTSUPP;
break;
}
}
} else {
ret = pret < 0 ? pret : -EFAULT;
}
up_read(&current->mm->mmap_sem);
if (ret) {
/*
* if we did partial map, or found file backed vmas,
* release any pages we did get
*/
if (pret > 0)
put_user_pages(pages, pret);
if (ctx->account_mem)
io_unaccount_mem(ctx->user, nr_pages);
kvfree(imu->bvec);
goto err;
}
off = ubuf & ~PAGE_MASK;
size = iov.iov_len;
for (j = 0; j < nr_pages; j++) {
size_t vec_len;
vec_len = min_t(size_t, size, PAGE_SIZE - off);
imu->bvec[j].bv_page = pages[j];
imu->bvec[j].bv_len = vec_len;
imu->bvec[j].bv_offset = off;
off = 0;
size -= vec_len;
}
/* store original address for later verification */
imu->ubuf = ubuf;
imu->len = iov.iov_len;
imu->nr_bvecs = nr_pages;
ctx->nr_user_bufs++;
}
kvfree(pages);
kvfree(vmas);
return 0;
err:
kvfree(pages);
kvfree(vmas);
io_sqe_buffer_unregister(ctx);
return ret;
}
static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg)
{
__s32 __user *fds = arg;
int fd;
if (ctx->cq_ev_fd)
return -EBUSY;
if (copy_from_user(&fd, fds, sizeof(*fds)))
return -EFAULT;
ctx->cq_ev_fd = eventfd_ctx_fdget(fd);
if (IS_ERR(ctx->cq_ev_fd)) {
int ret = PTR_ERR(ctx->cq_ev_fd);
ctx->cq_ev_fd = NULL;
return ret;
}
return 0;
}
static int io_eventfd_unregister(struct io_ring_ctx *ctx)
{
if (ctx->cq_ev_fd) {
eventfd_ctx_put(ctx->cq_ev_fd);
ctx->cq_ev_fd = NULL;
return 0;
}
return -ENXIO;
}
static void io_ring_ctx_free(struct io_ring_ctx *ctx)
{
io_finish_async(ctx);
if (ctx->sqo_mm)
mmdrop(ctx->sqo_mm);
io_iopoll_reap_events(ctx);
io_sqe_buffer_unregister(ctx);
io_sqe_files_unregister(ctx);
io_eventfd_unregister(ctx);
#if defined(CONFIG_UNIX)
if (ctx->ring_sock) {
ctx->ring_sock->file = NULL; /* so that iput() is called */
sock_release(ctx->ring_sock);
}
#endif
io_mem_free(ctx->rings);
io_mem_free(ctx->sq_sqes);
percpu_ref_exit(&ctx->refs);
if (ctx->account_mem)
io_unaccount_mem(ctx->user,
ring_pages(ctx->sq_entries, ctx->cq_entries));
free_uid(ctx->user);
if (ctx->creds)
put_cred(ctx->creds);
kfree(ctx);
}
static __poll_t io_uring_poll(struct file *file, poll_table *wait)
{
struct io_ring_ctx *ctx = file->private_data;
__poll_t mask = 0;
poll_wait(file, &ctx->cq_wait, wait);
/*
* synchronizes with barrier from wq_has_sleeper call in
* io_commit_cqring
*/
smp_rmb();
if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head !=
ctx->rings->sq_ring_entries)
mask |= EPOLLOUT | EPOLLWRNORM;
if (READ_ONCE(ctx->rings->cq.head) != ctx->cached_cq_tail)
mask |= EPOLLIN | EPOLLRDNORM;
return mask;
}
static int io_uring_fasync(int fd, struct file *file, int on)
{
struct io_ring_ctx *ctx = file->private_data;
return fasync_helper(fd, file, on, &ctx->cq_fasync);
}
static void io_cancel_async_work(struct io_ring_ctx *ctx,
struct files_struct *files)
{
struct io_kiocb *req;
if (list_empty(&ctx->task_list))
return;
spin_lock_irq(&ctx->task_lock);
list_for_each_entry(req, &ctx->task_list, task_list) {
if (files && req->files != files)
continue;
/*
* The below executes an smp_mb(), which matches with the
* smp_mb() (A) in io_sq_wq_submit_work() such that either
* we store REQ_F_CANCEL flag to req->flags or we see the
* req->work_task setted in io_sq_wq_submit_work().
*/
smp_store_mb(req->flags, req->flags | REQ_F_CANCEL); /* B */
if (req->work_task)
send_sig(SIGINT, req->work_task, 1);
}
spin_unlock_irq(&ctx->task_lock);
}
static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
{
mutex_lock(&ctx->uring_lock);
percpu_ref_kill(&ctx->refs);
mutex_unlock(&ctx->uring_lock);
io_cancel_async_work(ctx, NULL);
io_kill_timeouts(ctx);
io_poll_remove_all(ctx);
io_iopoll_reap_events(ctx);
wait_for_completion(&ctx->ctx_done);
io_ring_ctx_free(ctx);
}
static int io_uring_flush(struct file *file, void *data)
{
struct io_ring_ctx *ctx = file->private_data;
if (fatal_signal_pending(current) || (current->flags & PF_EXITING))
io_cancel_async_work(ctx, data);
return 0;
}
static int io_uring_release(struct inode *inode, struct file *file)
{
struct io_ring_ctx *ctx = file->private_data;
file->private_data = NULL;
io_ring_ctx_wait_and_kill(ctx);
return 0;
}
static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
{
loff_t offset = (loff_t) vma->vm_pgoff << PAGE_SHIFT;
unsigned long sz = vma->vm_end - vma->vm_start;
struct io_ring_ctx *ctx = file->private_data;
unsigned long pfn;
struct page *page;
void *ptr;
switch (offset) {
case IORING_OFF_SQ_RING:
case IORING_OFF_CQ_RING:
ptr = ctx->rings;
break;
case IORING_OFF_SQES:
ptr = ctx->sq_sqes;
break;
default:
return -EINVAL;
}
page = virt_to_head_page(ptr);
if (sz > page_size(page))
return -EINVAL;
pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
}
SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
u32, min_complete, u32, flags, const sigset_t __user *, sig,
size_t, sigsz)
{
struct io_ring_ctx *ctx;
long ret = -EBADF;
int submitted = 0;
struct fd f;
if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP))
return -EINVAL;
f = fdget(fd);
if (!f.file)
return -EBADF;
ret = -EOPNOTSUPP;
if (f.file->f_op != &io_uring_fops)
goto out_fput;
ret = -ENXIO;
ctx = f.file->private_data;
if (!percpu_ref_tryget(&ctx->refs))
goto out_fput;
/*
* For SQ polling, the thread will do all submissions and completions.
* Just return the requested submit count, and wake the thread if
* we were asked to.
*/
ret = 0;
if (ctx->flags & IORING_SETUP_SQPOLL) {
if (flags & IORING_ENTER_SQ_WAKEUP)
wake_up(&ctx->sqo_wait);
submitted = to_submit;
} else if (to_submit) {
to_submit = min(to_submit, ctx->sq_entries);
mutex_lock(&ctx->uring_lock);
submitted = io_ring_submit(ctx, to_submit);
mutex_unlock(&ctx->uring_lock);
if (submitted != to_submit)
goto out;
}
if (flags & IORING_ENTER_GETEVENTS) {
unsigned nr_events = 0;
min_complete = min(min_complete, ctx->cq_entries);
if (ctx->flags & IORING_SETUP_IOPOLL) {
ret = io_iopoll_check(ctx, &nr_events, min_complete);
} else {
ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
}
}
out:
percpu_ref_put(&ctx->refs);
out_fput:
fdput(f);
return submitted ? submitted : ret;
}
static const struct file_operations io_uring_fops = {
.release = io_uring_release,
.flush = io_uring_flush,
.mmap = io_uring_mmap,
.poll = io_uring_poll,
.fasync = io_uring_fasync,
};
static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
struct io_uring_params *p)
{
struct io_rings *rings;
size_t size, sq_array_offset;
/* make sure these are sane, as we already accounted them */
ctx->sq_entries = p->sq_entries;
ctx->cq_entries = p->cq_entries;
size = rings_size(p->sq_entries, p->cq_entries, &sq_array_offset);
if (size == SIZE_MAX)
return -EOVERFLOW;
rings = io_mem_alloc(size);
if (!rings)
return -ENOMEM;
ctx->rings = rings;
ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
rings->sq_ring_mask = p->sq_entries - 1;
rings->cq_ring_mask = p->cq_entries - 1;
rings->sq_ring_entries = p->sq_entries;
rings->cq_ring_entries = p->cq_entries;
ctx->sq_mask = rings->sq_ring_mask;
ctx->cq_mask = rings->cq_ring_mask;
size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
if (size == SIZE_MAX) {
io_mem_free(ctx->rings);
ctx->rings = NULL;
return -EOVERFLOW;
}
ctx->sq_sqes = io_mem_alloc(size);
if (!ctx->sq_sqes) {
io_mem_free(ctx->rings);
ctx->rings = NULL;
return -ENOMEM;
}
return 0;
}
/*
* Allocate an anonymous fd, this is what constitutes the application
* visible backing of an io_uring instance. The application mmaps this
* fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
* we have to tie this fd to a socket for file garbage collection purposes.
*/
static int io_uring_get_fd(struct io_ring_ctx *ctx)
{
struct file *file;
int ret;
#if defined(CONFIG_UNIX)
ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
&ctx->ring_sock);
if (ret)
return ret;
#endif
ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
if (ret < 0)
goto err;
file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
O_RDWR | O_CLOEXEC);
if (IS_ERR(file)) {
put_unused_fd(ret);
ret = PTR_ERR(file);
goto err;
}
#if defined(CONFIG_UNIX)
ctx->ring_sock->file = file;
ctx->ring_sock->sk->sk_user_data = ctx;
#endif
fd_install(ret, file);
return ret;
err:
#if defined(CONFIG_UNIX)
sock_release(ctx->ring_sock);
ctx->ring_sock = NULL;
#endif
return ret;
}
static int io_uring_create(unsigned entries, struct io_uring_params *p)
{
struct user_struct *user = NULL;
struct io_ring_ctx *ctx;
bool account_mem;
int ret;
if (!entries || entries > IORING_MAX_ENTRIES)
return -EINVAL;
/*
* Use twice as many entries for the CQ ring. It's possible for the
* application to drive a higher depth than the size of the SQ ring,
* since the sqes are only used at submission time. This allows for
* some flexibility in overcommitting a bit.
*/
p->sq_entries = roundup_pow_of_two(entries);
p->cq_entries = 2 * p->sq_entries;
user = get_uid(current_user());
account_mem = !capable(CAP_IPC_LOCK);
if (account_mem) {
ret = io_account_mem(user,
ring_pages(p->sq_entries, p->cq_entries));
if (ret) {
free_uid(user);
return ret;
}
}
ctx = io_ring_ctx_alloc(p);
if (!ctx) {
if (account_mem)
io_unaccount_mem(user, ring_pages(p->sq_entries,
p->cq_entries));
free_uid(user);
return -ENOMEM;
}
ctx->compat = in_compat_syscall();
ctx->account_mem = account_mem;
ctx->user = user;
ctx->creds = get_current_cred();
if (!ctx->creds) {
ret = -ENOMEM;
goto err;
}
ret = io_allocate_scq_urings(ctx, p);
if (ret)
goto err;
ret = io_sq_offload_start(ctx, p);
if (ret)
goto err;
memset(&p->sq_off, 0, sizeof(p->sq_off));
p->sq_off.head = offsetof(struct io_rings, sq.head);
p->sq_off.tail = offsetof(struct io_rings, sq.tail);
p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
p->sq_off.flags = offsetof(struct io_rings, sq_flags);
p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
memset(&p->cq_off, 0, sizeof(p->cq_off));
p->cq_off.head = offsetof(struct io_rings, cq.head);
p->cq_off.tail = offsetof(struct io_rings, cq.tail);
p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
p->cq_off.cqes = offsetof(struct io_rings, cqes);
/*
* Install ring fd as the very last thing, so we don't risk someone
* having closed it before we finish setup
*/
ret = io_uring_get_fd(ctx);
if (ret < 0)
goto err;
p->features = IORING_FEAT_SINGLE_MMAP;
return ret;
err:
io_ring_ctx_wait_and_kill(ctx);
return ret;
}
/*
* Sets up an aio uring context, and returns the fd. Applications asks for a
* ring size, we return the actual sq/cq ring sizes (among other things) in the
* params structure passed in.
*/
static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
{
struct io_uring_params p;
long ret;
int i;
if (copy_from_user(&p, params, sizeof(p)))
return -EFAULT;
for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
if (p.resv[i])
return -EINVAL;
}
if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
IORING_SETUP_SQ_AFF))
return -EINVAL;
ret = io_uring_create(entries, &p);
if (ret < 0)
return ret;
if (copy_to_user(params, &p, sizeof(p)))
return -EFAULT;
return ret;
}
SYSCALL_DEFINE2(io_uring_setup, u32, entries,
struct io_uring_params __user *, params)
{
return io_uring_setup(entries, params);
}
static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
void __user *arg, unsigned nr_args)
__releases(ctx->uring_lock)
__acquires(ctx->uring_lock)
{
int ret;
/*
* We're inside the ring mutex, if the ref is already dying, then
* someone else killed the ctx or is already going through
* io_uring_register().
*/
if (percpu_ref_is_dying(&ctx->refs))
return -ENXIO;
percpu_ref_kill(&ctx->refs);
/*
* Drop uring mutex before waiting for references to exit. If another
* thread is currently inside io_uring_enter() it might need to grab
* the uring_lock to make progress. If we hold it here across the drain
* wait, then we can deadlock. It's safe to drop the mutex here, since
* no new references will come in after we've killed the percpu ref.
*/
mutex_unlock(&ctx->uring_lock);
wait_for_completion(&ctx->ctx_done);
mutex_lock(&ctx->uring_lock);
switch (opcode) {
case IORING_REGISTER_BUFFERS:
ret = io_sqe_buffer_register(ctx, arg, nr_args);
break;
case IORING_UNREGISTER_BUFFERS:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_sqe_buffer_unregister(ctx);
break;
case IORING_REGISTER_FILES:
ret = io_sqe_files_register(ctx, arg, nr_args);
break;
case IORING_UNREGISTER_FILES:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_sqe_files_unregister(ctx);
break;
case IORING_REGISTER_EVENTFD:
ret = -EINVAL;
if (nr_args != 1)
break;
ret = io_eventfd_register(ctx, arg);
break;
case IORING_UNREGISTER_EVENTFD:
ret = -EINVAL;
if (arg || nr_args)
break;
ret = io_eventfd_unregister(ctx);
break;
default:
ret = -EINVAL;
break;
}
/* bring the ctx back to life */
reinit_completion(&ctx->ctx_done);
percpu_ref_reinit(&ctx->refs);
return ret;
}
SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
void __user *, arg, unsigned int, nr_args)
{
struct io_ring_ctx *ctx;
long ret = -EBADF;
struct fd f;
f = fdget(fd);
if (!f.file)
return -EBADF;
ret = -EOPNOTSUPP;
if (f.file->f_op != &io_uring_fops)
goto out_fput;
ctx = f.file->private_data;
mutex_lock(&ctx->uring_lock);
ret = __io_uring_register(ctx, opcode, arg, nr_args);
mutex_unlock(&ctx->uring_lock);
out_fput:
fdput(f);
return ret;
}
static int __init io_uring_init(void)
{
req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
return 0;
};
__initcall(io_uring_init);
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