blob: 0fbb486a320e927bb47aa1ac63fcea6ef6284760 [file] [log] [blame]
// 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 <uapi/linux/io_uring.h>
#include "internal.h"
#define IORING_MAX_ENTRIES 4096
#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 offset
* IORING_OFF_SQ_RING.
*
* The offsets to the member fields are published through struct
* io_sqring_offsets when calling io_uring_setup.
*/
struct io_sq_ring {
/*
* Head and tail offsets into the ring; the offsets need to be
* masked to get valid indices.
*
* The kernel controls head and the application controls tail.
*/
struct io_uring r;
/*
* Bitmask to apply to head and tail offsets (constant, equals
* ring_entries - 1)
*/
u32 ring_mask;
/* Ring size (constant, power of 2) */
u32 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 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 flags;
/*
* 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 array[];
};
/*
* This data is shared with the application through the mmap at offset
* IORING_OFF_CQ_RING.
*
* The offsets to the member fields are published through struct
* io_cqring_offsets when calling io_uring_setup.
*/
struct io_cq_ring {
/*
* Head and tail offsets into the ring; the offsets need to be
* masked to get valid indices.
*
* The application controls head and the kernel tail.
*/
struct io_uring r;
/*
* Bitmask to apply to head and tail offsets (constant, equals
* ring_entries - 1)
*/
u32 ring_mask;
/* Ring size (constant, power of 2) */
u32 ring_entries;
/*
* 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 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[];
};
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_end;
size_t io_pages;
};
struct io_ring_ctx {
struct {
struct percpu_ref refs;
} ____cacheline_aligned_in_smp;
struct {
unsigned int flags;
bool compat;
bool account_mem;
/* SQ ring */
struct io_sq_ring *sq_ring;
unsigned cached_sq_head;
unsigned sq_entries;
unsigned sq_mask;
unsigned sq_thread_idle;
struct io_uring_sqe *sq_sqes;
struct list_head defer_list;
} ____cacheline_aligned_in_smp;
/* IO offload */
struct workqueue_struct *sqo_wq;
struct task_struct *sqo_thread; /* if using sq thread polling */
struct mm_struct *sqo_mm;
wait_queue_head_t sqo_wait;
struct {
/* CQ ring */
struct io_cq_ring *cq_ring;
unsigned cached_cq_tail;
unsigned cq_entries;
unsigned cq_mask;
struct wait_queue_head cq_wait;
struct fasync_struct *cq_fasync;
struct eventfd_ctx *cq_ev_fd;
} ____cacheline_aligned_in_smp;
/*
* 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;
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 sqe_submit {
const struct io_uring_sqe *sqe;
unsigned short index;
bool has_user;
bool needs_lock;
bool needs_fixed_file;
};
/*
* 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;
};
/*
* 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 sqe_submit submit;
struct io_ring_ctx *ctx;
struct list_head 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 */
u64 user_data;
u32 error; /* iopoll result from callback */
u32 sequence;
struct work_struct work;
};
#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 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, 0, GFP_KERNEL)) {
kfree(ctx);
return NULL;
}
ctx->flags = p->flags;
init_waitqueue_head(&ctx->cq_wait);
init_completion(&ctx->ctx_done);
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);
return ctx;
}
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 req->sequence > ctx->cached_cq_tail + ctx->sq_ring->dropped;
}
static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
if (list_empty(&ctx->defer_list))
return NULL;
req = list_first_entry(&ctx->defer_list, struct io_kiocb, list);
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_cq_ring *ring = ctx->cq_ring;
if (ctx->cached_cq_tail != READ_ONCE(ring->r.tail)) {
/* order cqe stores with ring update */
smp_store_release(&ring->r.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 void io_commit_cqring(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
__io_commit_cqring(ctx);
while ((req = io_get_deferred_req(ctx)) != NULL) {
req->flags |= REQ_F_IO_DRAINED;
queue_work(ctx->sqo_wq, &req->work);
}
}
static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
{
struct io_cq_ring *ring = ctx->cq_ring;
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(ring->r.head) == ring->ring_entries)
return NULL;
ctx->cached_cq_tail++;
return &ring->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 {
unsigned overflow = READ_ONCE(ctx->cq_ring->overflow);
WRITE_ONCE(ctx->cq_ring->overflow, overflow + 1);
}
}
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 void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
{
percpu_ref_put_many(&ctx->refs, refs);
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
}
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++;
}
req->ctx = ctx;
req->flags = 0;
/* one is dropped after submission, the other at completion */
refcount_set(&req->refs, 2);
return req;
out:
io_ring_drop_ctx_refs(ctx, 1);
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);
io_ring_drop_ctx_refs(ctx, *nr);
*nr = 0;
}
}
static void io_free_req(struct io_kiocb *req)
{
if (req->file && !(req->flags & REQ_F_FIXED_FILE))
fput(req->file);
io_ring_drop_ctx_refs(req->ctx, 1);
kmem_cache_free(req_cachep, req);
}
static void io_put_req(struct io_kiocb *req)
{
if (refcount_dec_and_test(&req->refs))
io_free_req(req);
}
/*
* 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->error);
(*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.
*/
if (req->flags & 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)) {
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);
}
mutex_unlock(&ctx->uring_lock);
}
static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
long min)
{
int ret = 0;
do {
int tmin = 0;
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());
return ret;
}
static void kiocb_end_write(struct kiocb *kiocb)
{
if (kiocb->ki_flags & IOCB_WRITE) {
struct inode *inode = file_inode(kiocb->ki_filp);
/*
* Tell lockdep we inherited freeze protection from submission
* thread.
*/
if (S_ISREG(inode->i_mode))
__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
file_end_write(kiocb->ki_filp);
}
}
static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
{
struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
kiocb_end_write(kiocb);
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);
kiocb_end_write(kiocb);
req->error = 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 (force_nonblock && !io_file_supports_async(req->file))
force_nonblock = false;
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->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;
req->error = 0;
kiocb->ki_flags |= IOCB_HIPRI;
kiocb->ki_complete = io_complete_rw_iopoll;
} 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)
iov_iter_advance(iter, offset);
/* don't drop a reference to these pages */
iter->type |= ITER_BVEC_FLAG_NO_REF;
return 0;
}
static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
const struct sqe_submit *s, struct iovec **iovec,
struct iov_iter *iter)
{
const struct io_uring_sqe *sqe = s->sqe;
void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
size_t sqe_len = READ_ONCE(sqe->len);
u8 opcode;
/*
* We're reading ->opcode for the second time, but the first read
* doesn't care whether it's _FIXED or not, so it doesn't matter
* whether ->opcode changes concurrently. The first read does care
* about whether it is a READ or a WRITE, so we don't trust this read
* for that purpose and instead let the caller pass in the read/write
* flag.
*/
opcode = READ_ONCE(sqe->opcode);
if (opcode == IORING_OP_READ_FIXED ||
opcode == IORING_OP_WRITE_FIXED) {
int ret = io_import_fixed(ctx, rw, sqe, iter);
*iovec = NULL;
return ret;
}
if (!s->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);
}
/*
* 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;
off_t io_end = kiocb->ki_pos + len;
if (filp == async_list->file && kiocb->ki_pos == async_list->io_end) {
unsigned long max_pages;
/* Use 8x RA size as a decent limiter for both reads/writes */
max_pages = filp->f_ra.ra_pages;
if (!max_pages)
max_pages = VM_READAHEAD_PAGES;
max_pages *= 8;
/* If max pages are exceeded, reset the state */
len >>= PAGE_SHIFT;
if (async_list->io_pages + len <= max_pages) {
req->flags |= REQ_F_SEQ_PREV;
async_list->io_pages += len;
} else {
io_end = 0;
async_list->io_pages = 0;
}
}
/* New file? Reset state. */
if (async_list->file != filp) {
async_list->io_pages = 0;
async_list->file = filp;
}
async_list->io_end = io_end;
}
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;
int 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;
if (unlikely(!file->f_op->read_iter))
return -EINVAL;
ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
if (ret)
return ret;
iov_count = iov_iter_count(&iter);
ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
if (!ret) {
ssize_t ret2;
/* Catch -EAGAIN return for forced non-blocking submission */
ret2 = call_read_iter(file, kiocb, &iter);
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;
int 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;
if (unlikely(!file->f_op->write_iter))
return -EINVAL;
ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
if (ret)
return 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 (S_ISREG(file_inode(file)->i_mode)) {
__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;
ret2 = call_write_iter(file, kiocb, &iter);
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);
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);
io_cqring_add_event(req->ctx, sqe->user_data, ret);
io_put_req(req);
return 0;
}
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);
queue_work(req->ctx->sqo_wq, &req->work);
}
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;
__poll_t mask = 0;
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);
return;
}
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);
}
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 {
queue_work(ctx->sqo_wq, &req->work);
}
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 (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;
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);
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 int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
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(sqe_copy, 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, opcode;
if (unlikely(s->index >= ctx->sq_entries))
return -EINVAL;
req->user_data = READ_ONCE(s->sqe->user_data);
opcode = READ_ONCE(s->sqe->opcode);
switch (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;
default:
ret = -EINVAL;
break;
}
if (ret)
return ret;
if (ctx->flags & IORING_SETUP_IOPOLL) {
if (req->error == -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_sqe(struct io_ring_ctx *ctx,
const struct io_uring_sqe *sqe)
{
switch (sqe->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_sqe_needs_user(const struct io_uring_sqe *sqe)
{
u8 opcode = READ_ONCE(sqe->opcode);
return !(opcode == IORING_OP_READ_FIXED ||
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 io_ring_ctx *ctx = req->ctx;
struct mm_struct *cur_mm = NULL;
struct async_list *async_list;
LIST_HEAD(req_list);
mm_segment_t old_fs;
int ret;
async_list = io_async_list_from_sqe(ctx, req->submit.sqe);
restart:
do {
struct sqe_submit *s = &req->submit;
const struct io_uring_sqe *sqe = s->sqe;
/* Ensure we clear previously set non-block flag */
req->rw.ki_flags &= ~IOCB_NOWAIT;
ret = 0;
if (io_sqe_needs_user(sqe) && !cur_mm) {
if (!mmget_not_zero(ctx->sqo_mm)) {
ret = -EFAULT;
} else {
cur_mm = ctx->sqo_mm;
use_mm(cur_mm);
old_fs = get_fs();
set_fs(USER_DS);
}
}
if (!ret) {
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);
}
/* 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);
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);
}
}
if (cur_mm) {
set_fs(old_fs);
unuse_mm(cur_mm);
mmput(cur_mm);
}
}
/*
* 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 = false;
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);
if (!atomic_read(&list->cnt)) {
list_del_init(&req->list);
ret = false;
}
spin_unlock(&list->lock);
return ret;
}
static bool io_op_needs_file(const struct io_uring_sqe *sqe)
{
int op = READ_ONCE(sqe->opcode);
switch (op) {
case IORING_OP_NOP:
case IORING_OP_POLL_REMOVE:
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;
req->sequence = ctx->cached_sq_head - 1;
}
if (!io_op_needs_file(s->sqe)) {
req->file = NULL;
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_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
struct io_submit_state *state)
{
struct io_kiocb *req;
int ret;
/* enforce forwards compatibility on users */
if (unlikely(s->sqe->flags & ~(IOSQE_FIXED_FILE | IOSQE_IO_DRAIN)))
return -EINVAL;
req = io_get_req(ctx, state);
if (unlikely(!req))
return -EAGAIN;
ret = io_req_set_file(ctx, s, state, req);
if (unlikely(ret))
goto out;
ret = io_req_defer(ctx, req, s->sqe);
if (ret) {
if (ret == -EIOCBQUEUED)
ret = 0;
return ret;
}
ret = __io_submit_sqe(ctx, req, s, true);
if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
struct io_uring_sqe *sqe_copy;
sqe_copy = kmalloc(sizeof(*sqe_copy), GFP_KERNEL);
if (sqe_copy) {
struct async_list *list;
memcpy(sqe_copy, s->sqe, sizeof(*sqe_copy));
s->sqe = sqe_copy;
memcpy(&req->submit, s, sizeof(*s));
list = io_async_list_from_sqe(ctx, s->sqe);
if (!io_add_to_prev_work(list, req)) {
if (list)
atomic_inc(&list->cnt);
INIT_WORK(&req->work, io_sq_wq_submit_work);
queue_work(ctx->sqo_wq, &req->work);
}
/*
* Queued up for async execution, worker will release
* submit reference when the iocb is actually
* submitted.
*/
return 0;
}
}
out:
/* drop submission reference */
io_put_req(req);
/* and drop final reference, if we failed */
if (ret)
io_put_req(req);
return ret;
}
/*
* 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_sq_ring *ring = ctx->sq_ring;
if (ctx->cached_sq_head != READ_ONCE(ring->r.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(&ring->r.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_sq_ring *ring = ctx->sq_ring;
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(&ring->r.tail))
return false;
head = READ_ONCE(ring->array[head & ctx->sq_mask]);
if (head < ctx->sq_entries) {
s->index = head;
s->sqe = &ctx->sq_sqes[head];
ctx->cached_sq_head++;
return true;
}
/* drop invalid entries */
ctx->cached_sq_head++;
ring->dropped++;
return false;
}
static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
unsigned int nr, bool has_user, bool mm_fault)
{
struct io_submit_state state, *statep = NULL;
int ret, i, submitted = 0;
if (nr > IO_PLUG_THRESHOLD) {
io_submit_state_start(&state, ctx, nr);
statep = &state;
}
for (i = 0; i < nr; i++) {
if (unlikely(mm_fault)) {
ret = -EFAULT;
} else {
sqes[i].has_user = has_user;
sqes[i].needs_lock = true;
sqes[i].needs_fixed_file = true;
ret = io_submit_sqe(ctx, &sqes[i], statep);
}
if (!ret) {
submitted++;
continue;
}
io_cqring_add_event(ctx, sqes[i].sqe->user_data, ret);
}
if (statep)
io_submit_state_end(&state);
return submitted;
}
static int io_sq_thread(void *data)
{
struct sqe_submit sqes[IO_IOPOLL_BATCH];
struct io_ring_ctx *ctx = data;
struct mm_struct *cur_mm = NULL;
mm_segment_t old_fs;
DEFINE_WAIT(wait);
unsigned inflight;
unsigned long timeout;
old_fs = get_fs();
set_fs(USER_DS);
timeout = inflight = 0;
while (!kthread_should_park()) {
bool all_fixed, mm_fault = false;
int i;
if (inflight) {
unsigned nr_events = 0;
if (ctx->flags & IORING_SETUP_IOPOLL) {
/*
* 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);
io_iopoll_check(ctx, &nr_events, 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;
}
if (!io_get_sqring(ctx, &sqes[0])) {
/*
* 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)) {
cpu_relax();
continue;
}
/*
* 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;
}
prepare_to_wait(&ctx->sqo_wait, &wait,
TASK_INTERRUPTIBLE);
/* Tell userspace we may need a wakeup call */
ctx->sq_ring->flags |= IORING_SQ_NEED_WAKEUP;
/* make sure to read SQ tail after writing flags */
smp_mb();
if (!io_get_sqring(ctx, &sqes[0])) {
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->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP;
continue;
}
finish_wait(&ctx->sqo_wait, &wait);
ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP;
}
i = 0;
all_fixed = true;
do {
if (all_fixed && io_sqe_needs_user(sqes[i].sqe))
all_fixed = false;
i++;
if (i == ARRAY_SIZE(sqes))
break;
} while (io_get_sqring(ctx, &sqes[i]));
/* Unless all new commands are FIXED regions, grab mm */
if (!all_fixed && !cur_mm) {
mm_fault = !mmget_not_zero(ctx->sqo_mm);
if (!mm_fault) {
use_mm(ctx->sqo_mm);
cur_mm = ctx->sqo_mm;
}
}
inflight += io_submit_sqes(ctx, sqes, i, 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);
}
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;
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;
int ret;
if (!io_get_sqring(ctx, &s))
break;
s.has_user = true;
s.needs_lock = false;
s.needs_fixed_file = false;
submit++;
ret = io_submit_sqe(ctx, &s, statep);
if (ret)
io_cqring_add_event(ctx, s.sqe->user_data, ret);
}
io_commit_sqring(ctx);
if (statep)
io_submit_state_end(statep);
return submit;
}
static unsigned io_cqring_events(struct io_cq_ring *ring)
{
/* See comment at the top of this file */
smp_rmb();
return READ_ONCE(ring->r.tail) - READ_ONCE(ring->r.head);
}
/*
* 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_cq_ring *ring = ctx->cq_ring;
sigset_t ksigmask, sigsaved;
int ret;
if (io_cqring_events(ring) >= min_events)
return 0;
if (sig) {
#ifdef CONFIG_COMPAT
if (in_compat_syscall())
ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
&ksigmask, &sigsaved, sigsz);
else
#endif
ret = set_user_sigmask(sig, &ksigmask,
&sigsaved, sigsz);
if (ret)
return ret;
}
ret = wait_event_interruptible(ctx->wait, io_cqring_events(ring) >= min_events);
if (ret == -ERESTARTSYS)
ret = -EINTR;
if (sig)
restore_user_sigmask(sig, &sigsaved);
return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.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) {
/*
* 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)
{
io_sq_thread_stop(ctx);
if (ctx->sqo_wq) {
destroy_workqueue(ctx->sqo_wq);
ctx->sqo_wq = NULL;
}
}
#if defined(CONFIG_UNIX)
static void io_destruct_skb(struct sk_buff *skb)
{
struct io_ring_ctx *ctx = skb->sk->sk_user_data;
io_finish_async(ctx);
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;
if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
unsigned long inflight = ctx->user->unix_inflight + nr;
if (inflight > task_rlimit(current, RLIMIT_NOFILE))
return -EMFILE;
}
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->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;
init_waitqueue_head(&ctx->sqo_wait);
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 = alloc_workqueue("io_ring-wq", WQ_UNBOUND | WQ_FREEZABLE,
min(ctx->sq_entries - 1, 2 * num_online_cpus()));
if (!ctx->sqo_wq) {
ret = -ENOMEM;
goto err;
}
return 0;
err:
io_sq_thread_stop(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 ring_pages(unsigned sq_entries, unsigned cq_entries)
{
struct io_sq_ring *sq_ring;
struct io_cq_ring *cq_ring;
size_t bytes;
bytes = struct_size(sq_ring, array, sq_entries);
bytes += array_size(sizeof(struct io_uring_sqe), sq_entries);
bytes += struct_size(cq_ring, cqes, cq_entries);
return (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
}
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_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) {
kfree(vmas);
kfree(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) {
for (j = 0; j < pret; j++)
put_page(pages[j]);
}
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)
sock_release(ctx->ring_sock);
#endif
io_mem_free(ctx->sq_ring);
io_mem_free(ctx->sq_sqes);
io_mem_free(ctx->cq_ring);
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);
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->sq_ring->r.tail) - ctx->cached_sq_head !=
ctx->sq_ring->ring_entries)
mask |= EPOLLOUT | EPOLLWRNORM;
if (READ_ONCE(ctx->cq_ring->r.head) != ctx->cached_cq_tail)
mask |= EPOLLIN | EPOLLRDNORM;
return mask;
}