static int io_read(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_rw_state __s, *s = &__s;
	struct iovec *iovec;
	struct kiocb *kiocb = &req->rw.kiocb;
	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
	struct io_async_rw *rw;
	ssize_t ret, ret2;
	loff_t *ppos;

	if (!req_has_async_data(req)) {
		ret = io_import_iovec(READ, req, &iovec, s, issue_flags);
		if (unlikely(ret < 0))
			return ret;
	} else {
		/*
		 * Safe and required to re-import if we're using provided
		 * buffers, as we dropped the selected one before retry.
		 */
		if (req->flags & REQ_F_BUFFER_SELECT) {
			ret = io_import_iovec(READ, req, &iovec, s, issue_flags);
			if (unlikely(ret < 0))
				return ret;
		}

		rw = req->async_data;
		s = &rw->s;
		/*
		 * We come here from an earlier attempt, restore our state to
		 * match in case it doesn't. It's cheap enough that we don't
		 * need to make this conditional.
		 */
		iov_iter_restore(&s->iter, &s->iter_state);
		iovec = NULL;
	}
	ret = io_rw_init_file(req, FMODE_READ);
	if (unlikely(ret)) {
		kfree(iovec);
		return ret;
	}
	req->result = iov_iter_count(&s->iter);

	if (force_nonblock) {
		/* If the file doesn't support async, just async punt */
		if (unlikely(!io_file_supports_nowait(req))) {
			ret = io_setup_async_rw(req, iovec, s, true);
			return ret ?: -EAGAIN;
		}
		kiocb->ki_flags |= IOCB_NOWAIT;
	} else {
		/* Ensure we clear previously set non-block flag */
		kiocb->ki_flags &= ~IOCB_NOWAIT;
	}

	ppos = io_kiocb_update_pos(req);

	ret = rw_verify_area(READ, req->file, ppos, req->result);
	if (unlikely(ret)) {
		kfree(iovec);
		return ret;
	}

	ret = io_iter_do_read(req, &s->iter);

	if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
		req->flags &= ~REQ_F_REISSUE;
		/* if we can poll, just do that */
		if (req->opcode == IORING_OP_READ && file_can_poll(req->file))
			return -EAGAIN;
		/* IOPOLL retry should happen for io-wq threads */
		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
			goto done;
		/* no retry on NONBLOCK nor RWF_NOWAIT */
		if (req->flags & REQ_F_NOWAIT)
			goto done;
		ret = 0;
	} else if (ret == -EIOCBQUEUED) {
		goto out_free;
	} else if (ret == req->result || ret <= 0 || !force_nonblock ||
		   (req->flags & REQ_F_NOWAIT) || !need_read_all(req)) {
		/* read all, failed, already did sync or don't want to retry */
		goto done;
	}

	/*
	 * Don't depend on the iter state matching what was consumed, or being
	 * untouched in case of error. Restore it and we'll advance it
	 * manually if we need to.
	 */
	iov_iter_restore(&s->iter, &s->iter_state);

	ret2 = io_setup_async_rw(req, iovec, s, true);
	if (ret2)
		return ret2;

	iovec = NULL;
	rw = req->async_data;
	s = &rw->s;
	/*
	 * Now use our persistent iterator and state, if we aren't already.
	 * We've restored and mapped the iter to match.
	 */

	do {
		/*
		 * We end up here because of a partial read, either from
		 * above or inside this loop. Advance the iter by the bytes
		 * that were consumed.
		 */
		iov_iter_advance(&s->iter, ret);
		if (!iov_iter_count(&s->iter))
			break;
		rw->bytes_done += ret;
		iov_iter_save_state(&s->iter, &s->iter_state);

		/* if we can retry, do so with the callbacks armed */
		if (!io_rw_should_retry(req)) {
			kiocb->ki_flags &= ~IOCB_WAITQ;
			return -EAGAIN;
		}

		/*
		 * Now retry read with the IOCB_WAITQ parts set in the iocb. If
		 * we get -EIOCBQUEUED, then we'll get a notification when the
		 * desired page gets unlocked. We can also get a partial read
		 * here, and if we do, then just retry at the new offset.
		 */
		ret = io_iter_do_read(req, &s->iter);
		if (ret == -EIOCBQUEUED)
			return 0;
		/* we got some bytes, but not all. retry. */
		kiocb->ki_flags &= ~IOCB_WAITQ;
		iov_iter_restore(&s->iter, &s->iter_state);
	} while (ret > 0);
done:
	kiocb_done(req, ret, issue_flags);
out_free:
	/* it's faster to check here then delegate to kfree */
	if (iovec)
		kfree(iovec);
	return 0;
}


 */
static void io_submit_state_end(struct io_ring_ctx *ctx)
{
	struct io_submit_state *state = &ctx->submit_state;

	if (state->link.head)
		io_queue_sqe(state->link.head);
	/* flush only after queuing links as they can generate completions */
	io_submit_flush_completions(ctx);
	if (state->plug_started)
		blk_finish_plug(&state->plug);

io_uring: fix uninitialized field in rw io_kiocb

io_rw_init_file does not initialize kiocb->private, so when iocb_bio_iopoll
reads kiocb->private it can contain uninitialized data.

Fixes: 3e08773c3841 ("block: switch polling to be bio based")
Signed-off-by: Joseph Ravichandran <jravi@mit.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>


static __cold void io_sqd_update_thread_idle(struct io_sq_data *sqd)
{
	struct io_ring_ctx *ctx;
	unsigned sq_thread_idle = 0;

	list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
		sq_thread_idle = max(sq_thread_idle, ctx->sq_thread_idle);
	sqd->sq_thread_idle = sq_thread_idle;


static __cold bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
{
	struct io_kiocb *req = container_of(work, struct io_kiocb, work);

	return req->ctx == data;


static void io_req_task_queue_reissue(struct io_kiocb *req)
{
	req->io_task_work.func = io_queue_async_work;
	io_req_task_work_add(req, false);
}


static u64 *io_get_tag_slot(struct io_rsrc_data *data, unsigned int idx)
{
	unsigned int off = idx & IO_RSRC_TAG_TABLE_MASK;
	unsigned int table_idx = idx >> IO_RSRC_TAG_TABLE_SHIFT;

	return &data->tags[table_idx][off];


static struct io_rsrc_node *io_rsrc_node_alloc(void)
{
	struct io_rsrc_node *ref_node;

	ref_node = kzalloc(sizeof(*ref_node), GFP_KERNEL);
	if (!ref_node)
		return NULL;

	if (percpu_ref_init(&ref_node->refs, io_rsrc_node_ref_zero,
			    0, GFP_KERNEL)) {
		kfree(ref_node);
		return NULL;
	}
	INIT_LIST_HEAD(&ref_node->node);
	INIT_LIST_HEAD(&ref_node->rsrc_list);
	ref_node->done = false;
	return ref_node;


static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages,
				 int nr_pages, struct io_mapped_ubuf *imu,
				 struct page **last_hpage)
{
	int i, ret;

	imu->acct_pages = 0;
	for (i = 0; i < nr_pages; i++) {
		if (!PageCompound(pages[i])) {
			imu->acct_pages++;
		} else {
			struct page *hpage;

			hpage = compound_head(pages[i]);
			if (hpage == *last_hpage)
				continue;
			*last_hpage = hpage;
			if (headpage_already_acct(ctx, pages, i, hpage))
				continue;
			imu->acct_pages += page_size(hpage) >> PAGE_SHIFT;
		}
	}

	if (!imu->acct_pages)
		return 0;

	ret = io_account_mem(ctx, imu->acct_pages);
	if (ret)
		imu->acct_pages = 0;
	return ret;


	__must_hold(&ctx->uring_lock)
{
	struct percpu_ref *ref = req->fixed_rsrc_refs;

	if (ref) {
		if (ref == &ctx->rsrc_node->refs)
			ctx->rsrc_cached_refs++;
		else
			percpu_ref_put(ref);
	}
}


	__must_hold(&ctx->uring_lock)
{
	ctx->rsrc_cached_refs += IO_RSRC_REF_BATCH;
	percpu_ref_get_many(&ctx->rsrc_node->refs, IO_RSRC_REF_BATCH);
}


static int io_ring_add_registered_fd(struct io_uring_task *tctx, int fd,
				     int start, int end)
{
	struct file *file;
	int offset;

	for (offset = start; offset < end; offset++) {
		offset = array_index_nospec(offset, IO_RINGFD_REG_MAX);
		if (tctx->registered_rings[offset])
			continue;

		file = fget(fd);
		if (!file) {
			return -EBADF;
		} else if (file->f_op != &io_uring_fops) {
			fput(file);
			return -EOPNOTSUPP;
		}
		tctx->registered_rings[offset] = file;
		return offset;
	}

	return -EBUSY;


static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
				    unsigned int issue_flags)
{
	if (req->flags & REQ_F_BUFFER_SELECTED) {
		struct io_buffer *kbuf = req->kbuf;

		iov[0].iov_base = u64_to_user_ptr(kbuf->addr);
		iov[0].iov_len = kbuf->len;
		return 0;
	}
	if (req->rw.len != 1)
		return -EINVAL;

#ifdef CONFIG_COMPAT
	if (req->ctx->compat)
		return io_compat_import(req, iov, issue_flags);
#endif

	return __io_iov_buffer_select(req, iov, issue_flags);
}


static void io_init_poll_iocb(struct io_poll_iocb *poll, __poll_t events,
			      wait_queue_func_t wake_func)
{
	poll->head = NULL;
#define IO_POLL_UNMASK	(EPOLLERR|EPOLLHUP|EPOLLNVAL|EPOLLRDHUP)
	/* mask in events that we always want/need */
	poll->events = events | IO_POLL_UNMASK;
	INIT_LIST_HEAD(&poll->wait.entry);
	init_waitqueue_func_entry(&poll->wait, wake_func);


static bool __io_file_supports_nowait(struct file *file, umode_t mode)
{
	if (S_ISBLK(mode)) {
		if (IS_ENABLED(CONFIG_BLOCK) &&
		    io_bdev_nowait(I_BDEV(file->f_mapping->host)))
			return true;
		return false;
	}
	if (S_ISSOCK(mode))
		return true;
	if (S_ISREG(mode)) {
		if (IS_ENABLED(CONFIG_BLOCK) &&
		    io_bdev_nowait(file->f_inode->i_sb->s_bdev) &&
		    file->f_op != &io_uring_fops)
			return true;
		return false;
	}

	/* any ->read/write should understand O_NONBLOCK */
	if (file->f_flags & O_NONBLOCK)
		return true;
	return file->f_mode & FMODE_NOWAIT;
}


static unsigned int io_file_get_flags(struct file *file)
{
	umode_t mode = file_inode(file)->i_mode;
	unsigned int res = 0;

	if (S_ISREG(mode))
		res |= FFS_ISREG;
	if (__io_file_supports_nowait(file, mode))
		res |= FFS_NOWAIT;
	return res;
}


static struct iovec *__io_import_iovec(int rw, struct io_kiocb *req,
				       struct io_rw_state *s,
				       unsigned int issue_flags)
{
	struct iov_iter *iter = &s->iter;
	u8 opcode = req->opcode;
	struct iovec *iovec;
	void __user *buf;
	size_t sqe_len;
	ssize_t ret;

	if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
		ret = io_import_fixed(req, rw, iter, issue_flags);
		if (ret)
			return ERR_PTR(ret);
		return NULL;
	}

	/* buffer index only valid with fixed read/write, or buffer select  */
	if (unlikely(req->buf_index && !(req->flags & REQ_F_BUFFER_SELECT)))
		return ERR_PTR(-EINVAL);

	buf = u64_to_user_ptr(req->rw.addr);
	sqe_len = req->rw.len;

	if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE) {
		if (req->flags & REQ_F_BUFFER_SELECT) {
			buf = io_rw_buffer_select(req, &sqe_len, issue_flags);
			if (IS_ERR(buf))
				return ERR_CAST(buf);
			req->rw.len = sqe_len;
		}

		ret = import_single_range(rw, buf, sqe_len, s->fast_iov, iter);
		if (ret)
			return ERR_PTR(ret);
		return NULL;
	}

	iovec = s->fast_iov;
	if (req->flags & REQ_F_BUFFER_SELECT) {
		ret = io_iov_buffer_select(req, iovec, issue_flags);
		if (ret)
			return ERR_PTR(ret);
		iov_iter_init(iter, rw, iovec, 1, iovec->iov_len);
		return NULL;
	}

	ret = __import_iovec(rw, buf, sqe_len, UIO_FASTIOV, &iovec, iter,
			      req->ctx->compat);
	if (unlikely(ret < 0))
		return ERR_PTR(ret);
	return iovec;
}


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++) {
		struct file *file;

		file = io_file_from_index(ctx, i);
		if (file)
			fput(file);
	}
#endif
	io_free_file_tables(&ctx->file_table);
	io_rsrc_data_free(ctx->file_data);
	ctx->file_data = NULL;
	ctx->nr_user_files = 0;


static void io_buffer_add_list(struct io_ring_ctx *ctx,
			       struct io_buffer_list *bl, unsigned int bgid)
{
	struct list_head *list;

	list = &ctx->io_buffers[hash_32(bgid, IO_BUFFERS_HASH_BITS)];
	INIT_LIST_HEAD(&bl->buf_list);
	bl->bgid = bgid;
	list_add(&bl->list, list);
}


static void io_req_caches_free(struct io_ring_ctx *ctx)
{
	struct io_submit_state *state = &ctx->submit_state;
	int nr = 0;

	mutex_lock(&ctx->uring_lock);
	io_flush_cached_locked_reqs(ctx, state);

	while (state->free_list.next) {
		struct io_wq_work_node *node;
		struct io_kiocb *req;

		node = wq_stack_extract(&state->free_list);
		req = container_of(node, struct io_kiocb, comp_list);
		kmem_cache_free(req_cachep, req);
		nr++;
	}
	if (nr)
		percpu_ref_put_many(&ctx->refs, nr);
	mutex_unlock(&ctx->uring_lock);


static int __init io_uring_init(void)
{
#define __BUILD_BUG_VERIFY_ELEMENT(stype, eoffset, etype, ename) do { \
	BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
	BUILD_BUG_ON(sizeof(etype) != sizeof_field(stype, ename)); \
} while (0)

#define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
	__BUILD_BUG_VERIFY_ELEMENT(struct io_uring_sqe, eoffset, etype, ename)
	BUILD_BUG_ON(sizeof(struct io_uring_sqe) != 64);
	BUILD_BUG_SQE_ELEM(0,  __u8,   opcode);
	BUILD_BUG_SQE_ELEM(1,  __u8,   flags);
	BUILD_BUG_SQE_ELEM(2,  __u16,  ioprio);
	BUILD_BUG_SQE_ELEM(4,  __s32,  fd);
	BUILD_BUG_SQE_ELEM(8,  __u64,  off);
	BUILD_BUG_SQE_ELEM(8,  __u64,  addr2);
	BUILD_BUG_SQE_ELEM(16, __u64,  addr);
	BUILD_BUG_SQE_ELEM(16, __u64,  splice_off_in);
	BUILD_BUG_SQE_ELEM(24, __u32,  len);
	BUILD_BUG_SQE_ELEM(28,     __kernel_rwf_t, rw_flags);
	BUILD_BUG_SQE_ELEM(28, /* compat */   int, rw_flags);
	BUILD_BUG_SQE_ELEM(28, /* compat */ __u32, rw_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  fsync_flags);
	BUILD_BUG_SQE_ELEM(28, /* compat */ __u16,  poll_events);
	BUILD_BUG_SQE_ELEM(28, __u32,  poll32_events);
	BUILD_BUG_SQE_ELEM(28, __u32,  sync_range_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  msg_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  timeout_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  accept_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  cancel_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  open_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  statx_flags);
	BUILD_BUG_SQE_ELEM(28, __u32,  fadvise_advice);
	BUILD_BUG_SQE_ELEM(28, __u32,  splice_flags);
	BUILD_BUG_SQE_ELEM(32, __u64,  user_data);
	BUILD_BUG_SQE_ELEM(40, __u16,  buf_index);
	BUILD_BUG_SQE_ELEM(40, __u16,  buf_group);
	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
	BUILD_BUG_SQE_ELEM(44, __u32,  file_index);

	BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
		     sizeof(struct io_uring_rsrc_update));
	BUILD_BUG_ON(sizeof(struct io_uring_rsrc_update) >
		     sizeof(struct io_uring_rsrc_update2));

	/* ->buf_index is u16 */
	BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));

	/* should fit into one byte */
	BUILD_BUG_ON(SQE_VALID_FLAGS >= (1 << 8));
	BUILD_BUG_ON(SQE_COMMON_FLAGS >= (1 << 8));
	BUILD_BUG_ON((SQE_VALID_FLAGS | SQE_COMMON_FLAGS) != SQE_VALID_FLAGS);

	BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST);
	BUILD_BUG_ON(__REQ_F_LAST_BIT > 8 * sizeof(int));

	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC |
				SLAB_ACCOUNT);
	return 0;


static int io_madvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
#if defined(CONFIG_ADVISE_SYSCALLS) && defined(CONFIG_MMU)
	if (sqe->ioprio || sqe->buf_index || sqe->off || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;

	req->madvise.addr = READ_ONCE(sqe->addr);
	req->madvise.len = READ_ONCE(sqe->len);
	req->madvise.advice = READ_ONCE(sqe->fadvise_advice);
	return 0;
#else
	return -EOPNOTSUPP;
#endif
}


static int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg,
				unsigned nr_args)
{
	struct io_uring_rsrc_update __user *arg = __arg;
	struct io_uring_task *tctx = current->io_uring;
	struct io_uring_rsrc_update reg;
	int ret = 0, i;

	if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
		return -EINVAL;
	if (!tctx)
		return 0;

	for (i = 0; i < nr_args; i++) {
		if (copy_from_user(&reg, &arg[i], sizeof(reg))) {
			ret = -EFAULT;
			break;
		}
		if (reg.resv || reg.offset >= IO_RINGFD_REG_MAX) {
			ret = -EINVAL;
			break;
		}

		reg.offset = array_index_nospec(reg.offset, IO_RINGFD_REG_MAX);
		if (tctx->registered_rings[reg.offset]) {
			fput(tctx->registered_rings[reg.offset]);
			tctx->registered_rings[reg.offset] = NULL;
		}
	}

	return i ? i : ret;


static inline void io_ring_set_wakeup_flag(struct io_ring_ctx *ctx)
{
	/* Tell userspace we may need a wakeup call */
	spin_lock(&ctx->completion_lock);
	WRITE_ONCE(ctx->rings->sq_flags,
		   ctx->rings->sq_flags | IORING_SQ_NEED_WAKEUP);
	spin_unlock(&ctx->completion_lock);


static bool io_net_retry(struct socket *sock, int flags)
{
	if (!(flags & MSG_WAITALL))
		return false;
	return sock->type == SOCK_STREAM || sock->type == SOCK_SEQPACKET;
}


static __cold void **io_alloc_page_table(size_t size)
{
	unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
	size_t init_size = size;
	void **table;

	table = kcalloc(nr_tables, sizeof(*table), GFP_KERNEL_ACCOUNT);
	if (!table)
		return NULL;

	for (i = 0; i < nr_tables; i++) {
		unsigned int this_size = min_t(size_t, size, PAGE_SIZE);

		table[i] = kzalloc(this_size, GFP_KERNEL_ACCOUNT);
		if (!table[i]) {
			io_free_page_table(table, init_size);
			return NULL;
		}
		size -= this_size;
	}
	return table;


			 const struct io_uring_sqe *sqe)
	__must_hold(&ctx->uring_lock)
{
	struct io_submit_link *link = &ctx->submit_state.link;
	int ret;

	ret = io_init_req(ctx, req, sqe);
	if (unlikely(ret)) {
		trace_io_uring_req_failed(sqe, ctx, req, ret);

		/* fail even hard links since we don't submit */
		if (link->head) {
			/*
			 * we can judge a link req is failed or cancelled by if
			 * REQ_F_FAIL is set, but the head is an exception since
			 * it may be set REQ_F_FAIL because of other req's failure
			 * so let's leverage req->result to distinguish if a head
			 * is set REQ_F_FAIL because of its failure or other req's
			 * failure so that we can set the correct ret code for it.
			 * init result here to avoid affecting the normal path.
			 */
			if (!(link->head->flags & REQ_F_FAIL))
				req_fail_link_node(link->head, -ECANCELED);
		} else if (!(req->flags & (REQ_F_LINK | REQ_F_HARDLINK))) {
			/*
			 * the current req is a normal req, we should return
			 * error and thus break the submittion loop.
			 */
			io_req_complete_failed(req, ret);
			return ret;
		}
		req_fail_link_node(req, ret);
	}

	/* don't need @sqe from now on */
	trace_io_uring_submit_sqe(ctx, req, req->user_data, req->opcode,
				  req->flags, true,
				  ctx->flags & IORING_SETUP_SQPOLL);

	/*
	 * 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->head) {
		struct io_kiocb *head = link->head;

		if (!(req->flags & REQ_F_FAIL)) {
			ret = io_req_prep_async(req);
			if (unlikely(ret)) {
				req_fail_link_node(req, ret);
				if (!(head->flags & REQ_F_FAIL))
					req_fail_link_node(head, -ECANCELED);
			}
		}
		trace_io_uring_link(ctx, req, head);
		link->last->link = req;
		link->last = req;

		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK))
			return 0;
		/* last request of a link, enqueue the link */
		link->head = NULL;
		req = head;
	} else if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
		link->head = req;
		link->last = req;
		return 0;
	}

	io_queue_sqe(req);
	return 0;


static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
{
	int ret, fd;

	fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
	if (fd < 0)
		return fd;

	ret = io_uring_add_tctx_node(ctx);
	if (ret) {
		put_unused_fd(fd);
		return ret;
	}
	fd_install(fd, file);
	return fd;


 */
static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
{
	struct io_uring_params p;
	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 | IORING_SETUP_CQSIZE |
			IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
			IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL))
		return -EINVAL;

	return  io_uring_create(entries, &p, params);


static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
			    struct wait_queue_head *head,
			    struct io_poll_iocb **poll_ptr)
{
	struct io_kiocb *req = pt->req;
	unsigned long wqe_private = (unsigned long) req;

	/*
	 * The file being polled uses multiple waitqueues for poll handling
	 * (e.g. one for read, one for write). Setup a separate io_poll_iocb
	 * if this happens.
	 */
	if (unlikely(pt->nr_entries)) {
		struct io_poll_iocb *first = poll;

		/* double add on the same waitqueue head, ignore */
		if (first->head == head)
			return;
		/* already have a 2nd entry, fail a third attempt */
		if (*poll_ptr) {
			if ((*poll_ptr)->head == head)
				return;
			pt->error = -EINVAL;
			return;
		}

		poll = kmalloc(sizeof(*poll), GFP_ATOMIC);
		if (!poll) {
			pt->error = -ENOMEM;
			return;
		}
		/* mark as double wq entry */
		wqe_private |= 1;
		req->flags |= REQ_F_DOUBLE_POLL;
		io_init_poll_iocb(poll, first->events, first->wait.func);
		*poll_ptr = poll;
		if (req->opcode == IORING_OP_POLL_ADD)
			req->flags |= REQ_F_ASYNC_DATA;
	}

	req->flags |= REQ_F_SINGLE_POLL;
	pt->nr_entries++;
	poll->head = head;
	poll->wait.private = (void *) wqe_private;

	if (poll->events & EPOLLEXCLUSIVE)
		add_wait_queue_exclusive(head, &poll->wait);
	else
		add_wait_queue(head, &poll->wait);


static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
{
	struct kiocb *kiocb = &req->rw.kiocb;
	struct file *file = req->file;
	ssize_t ret = 0;
	loff_t *ppos;

	/*
	 * 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) &&
	    !(kiocb->ki_filp->f_flags & O_NONBLOCK))
		return -EAGAIN;

	ppos = io_kiocb_ppos(kiocb);

	while (iov_iter_count(iter)) {
		struct iovec iovec;
		ssize_t nr;

		if (!iov_iter_is_bvec(iter)) {
			iovec = iov_iter_iovec(iter);
		} else {
			iovec.iov_base = u64_to_user_ptr(req->rw.addr);
			iovec.iov_len = req->rw.len;
		}

		if (rw == READ) {
			nr = file->f_op->read(file, iovec.iov_base,
					      iovec.iov_len, ppos);
		} else {
			nr = file->f_op->write(file, iovec.iov_base,
					       iovec.iov_len, ppos);
		}

		if (nr < 0) {
			if (!ret)
				ret = nr;
			break;
		}
		ret += nr;
		if (!iov_iter_is_bvec(iter)) {
			iov_iter_advance(iter, nr);
		} else {
			req->rw.addr += nr;
			req->rw.len -= nr;
			if (!req->rw.len)
				break;
		}
		if (nr != iovec.iov_len)
			break;
	}

	return ret;
}


static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_ring_ctx *ctx = req->ctx;
	u64 sqe_addr = req->cancel.addr;
	bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
	struct io_tctx_node *node;
	int ret;

	ret = io_try_cancel_userdata(req, sqe_addr);
	if (ret != -ENOENT)
		goto done;

	/* slow path, try all io-wq's */
	io_ring_submit_lock(ctx, needs_lock);
	ret = -ENOENT;
	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
		struct io_uring_task *tctx = node->task->io_uring;

		ret = io_async_cancel_one(tctx, req->cancel.addr, ctx);
		if (ret != -ENOENT)
			break;
	}
	io_ring_submit_unlock(ctx, needs_lock);
done:
	if (ret < 0)
		req_set_fail(req);
	io_req_complete_post(req, ret, 0);
	return 0;


static int io_fsync(struct io_kiocb *req, unsigned int issue_flags)
{
	loff_t end = req->sync.off + req->sync.len;
	int ret;

	/* fsync always requires a blocking context */
	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = vfs_fsync_range(req->file, req->sync.off,
				end > 0 ? end : LLONG_MAX,
				req->sync.flags & IORING_FSYNC_DATASYNC);
	if (ret < 0)
		req_set_fail(req);
	io_req_complete(req, ret);
	return 0;
}


static inline void io_req_complete_state(struct io_kiocb *req, s32 res,
					 u32 cflags)
{
	req->result = res;
	req->cflags = cflags;
	req->flags |= REQ_F_COMPLETE_INLINE;
}


static void io_complete_rw(struct kiocb *kiocb, long res)
{
	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);

	if (__io_complete_rw_common(req, res))
		return;
	req->result = res;
	req->io_task_work.func = io_req_task_complete;
	io_req_task_work_add(req, !!(req->ctx->flags & IORING_SETUP_SQPOLL));
}


 */
static inline int io_uring_add_tctx_node(struct io_ring_ctx *ctx)
{
	struct io_uring_task *tctx = current->io_uring;

	if (likely(tctx && tctx->last == ctx))
		return 0;
	return __io_uring_add_tctx_node(ctx);


static void io_queue_async_work(struct io_kiocb *req, bool *dont_use)
{
	struct io_ring_ctx *ctx = req->ctx;
	struct io_kiocb *link = io_prep_linked_timeout(req);
	struct io_uring_task *tctx = req->task->io_uring;

	BUG_ON(!tctx);
	BUG_ON(!tctx->io_wq);

	/* init ->work of the whole link before punting */
	io_prep_async_link(req);

	/*
	 * Not expected to happen, but if we do have a bug where this _can_
	 * happen, catch it here and ensure the request is marked as
	 * canceled. That will make io-wq go through the usual work cancel
	 * procedure rather than attempt to run this request (or create a new
	 * worker for it).
	 */
	if (WARN_ON_ONCE(!same_thread_group(req->task, current)))
		req->work.flags |= IO_WQ_WORK_CANCEL;

	trace_io_uring_queue_async_work(ctx, req, req->user_data, req->opcode, req->flags,
					&req->work, io_wq_is_hashed(&req->work));
	io_wq_enqueue(tctx->io_wq, &req->work);
	if (link)
		io_queue_linked_timeout(link);
}


static int io_poll_update(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_ring_ctx *ctx = req->ctx;
	struct io_kiocb *preq;
	int ret2, ret = 0;
	bool locked;

	spin_lock(&ctx->completion_lock);
	preq = io_poll_find(ctx, req->poll_update.old_user_data, true);
	if (!preq || !io_poll_disarm(preq)) {
		spin_unlock(&ctx->completion_lock);
		ret = preq ? -EALREADY : -ENOENT;
		goto out;
	}
	spin_unlock(&ctx->completion_lock);

	if (req->poll_update.update_events || req->poll_update.update_user_data) {
		/* only mask one event flags, keep behavior flags */
		if (req->poll_update.update_events) {
			preq->poll.events &= ~0xffff;
			preq->poll.events |= req->poll_update.events & 0xffff;
			preq->poll.events |= IO_POLL_UNMASK;
		}
		if (req->poll_update.update_user_data)
			preq->user_data = req->poll_update.new_user_data;

		ret2 = io_poll_add(preq, issue_flags);
		/* successfully updated, don't complete poll request */
		if (!ret2)
			goto out;
	}

	req_set_fail(preq);
	preq->result = -ECANCELED;
	locked = !(issue_flags & IO_URING_F_UNLOCKED);
	io_req_task_complete(preq, &locked);
out:
	if (ret < 0)
		req_set_fail(req);
	/* complete update request, we're done with it */
	__io_req_complete(req, issue_flags, ret, 0);
	return 0;


static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
				   unsigned int nr_args, u64 __user *tags)
{
	struct page *last_hpage = NULL;
	struct io_rsrc_data *data;
	int i, ret;
	struct iovec iov;

	if (ctx->user_bufs)
		return -EBUSY;
	if (!nr_args || nr_args > IORING_MAX_REG_BUFFERS)
		return -EINVAL;
	ret = io_rsrc_node_switch_start(ctx);
	if (ret)
		return ret;
	ret = io_rsrc_data_alloc(ctx, io_rsrc_buf_put, tags, nr_args, &data);
	if (ret)
		return ret;
	ret = io_buffers_map_alloc(ctx, nr_args);
	if (ret) {
		io_rsrc_data_free(data);
		return ret;
	}

	for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
		ret = io_copy_iov(ctx, &iov, arg, i);
		if (ret)
			break;
		ret = io_buffer_validate(&iov);
		if (ret)
			break;
		if (!iov.iov_base && *io_get_tag_slot(data, i)) {
			ret = -EINVAL;
			break;
		}

		ret = io_sqe_buffer_register(ctx, &iov, &ctx->user_bufs[i],
					     &last_hpage);
		if (ret)
			break;
	}

	WARN_ON_ONCE(ctx->buf_data);

	ctx->buf_data = data;
	if (ret)
		__io_sqe_buffers_unregister(ctx);
	else
		io_rsrc_node_switch(ctx, NULL);
	return ret;


	__must_hold(&ctx->completion_lock)
{
	u32 seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
	struct io_kiocb *req, *tmp;

	spin_lock_irq(&ctx->timeout_lock);
	list_for_each_entry_safe(req, tmp, &ctx->timeout_list, timeout.list) {
		u32 events_needed, events_got;

		if (io_is_timeout_noseq(req))
			break;

		/*
		 * Since seq can easily wrap around over time, subtract
		 * the last seq at which timeouts were flushed before comparing.
		 * Assuming not more than 2^31-1 events have happened since,
		 * these subtractions won't have wrapped, so we can check if
		 * target is in [last_seq, current_seq] by comparing the two.
		 */
		events_needed = req->timeout.target_seq - ctx->cq_last_tm_flush;
		events_got = seq - ctx->cq_last_tm_flush;
		if (events_got < events_needed)
			break;

		io_kill_timeout(req, 0);
	}
	ctx->cq_last_tm_flush = seq;
	spin_unlock_irq(&ctx->timeout_lock);
}


static int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_splice *sp = &req->splice;

	sp->off_in = READ_ONCE(sqe->splice_off_in);
	sp->off_out = READ_ONCE(sqe->off);
	return __io_splice_prep(req, sqe);
}


static void io_account_cq_overflow(struct io_ring_ctx *ctx)
{
	struct io_rings *r = ctx->rings;

	WRITE_ONCE(r->cq_overflow, READ_ONCE(r->cq_overflow) + 1);
	ctx->cq_extra--;
}


static bool io_rw_should_reissue(struct io_kiocb *req)
{
	umode_t mode = file_inode(req->file)->i_mode;
	struct io_ring_ctx *ctx = req->ctx;

	if (!S_ISBLK(mode) && !S_ISREG(mode))
		return false;
	if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
	    !(ctx->flags & IORING_SETUP_IOPOLL)))
		return false;
	/*
	 * If ref is dying, we might be running poll reap from the exit work.
	 * Don't attempt to reissue from that path, just let it fail with
	 * -EAGAIN.
	 */
	if (percpu_ref_is_dying(&ctx->refs))
		return false;
	/*
	 * Play it safe and assume not safe to re-import and reissue if we're
	 * not in the original thread group (or in task context).
	 */
	if (!same_thread_group(req->task, current) || !in_task())
		return false;
	return true;
}


static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
{
	struct open_flags op;
	struct file *file;
	bool resolve_nonblock, nonblock_set;
	bool fixed = !!req->open.file_slot;
	int ret;

	ret = build_open_flags(&req->open.how, &op);
	if (ret)
		goto err;
	nonblock_set = op.open_flag & O_NONBLOCK;
	resolve_nonblock = req->open.how.resolve & RESOLVE_CACHED;
	if (issue_flags & IO_URING_F_NONBLOCK) {
		/*
		 * Don't bother trying for O_TRUNC, O_CREAT, or O_TMPFILE open,
		 * it'll always -EAGAIN
		 */
		if (req->open.how.flags & (O_TRUNC | O_CREAT | O_TMPFILE))
			return -EAGAIN;
		op.lookup_flags |= LOOKUP_CACHED;
		op.open_flag |= O_NONBLOCK;
	}

	if (!fixed) {
		ret = __get_unused_fd_flags(req->open.how.flags, req->open.nofile);
		if (ret < 0)
			goto err;
	}

	file = do_filp_open(req->open.dfd, req->open.filename, &op);
	if (IS_ERR(file)) {
		/*
		 * We could hang on to this 'fd' on retrying, but seems like
		 * marginal gain for something that is now known to be a slower
		 * path. So just put it, and we'll get a new one when we retry.
		 */
		if (!fixed)
			put_unused_fd(ret);

		ret = PTR_ERR(file);
		/* only retry if RESOLVE_CACHED wasn't already set by application */
		if (ret == -EAGAIN &&
		    (!resolve_nonblock && (issue_flags & IO_URING_F_NONBLOCK)))
			return -EAGAIN;
		goto err;
	}

	if ((issue_flags & IO_URING_F_NONBLOCK) && !nonblock_set)
		file->f_flags &= ~O_NONBLOCK;
	fsnotify_open(file);

	if (!fixed)
		fd_install(ret, file);
	else
		ret = io_install_fixed_file(req, file, issue_flags,
					    req->open.file_slot - 1);
err:
	putname(req->open.filename);
	req->flags &= ~REQ_F_NEED_CLEANUP;
	if (ret < 0)
		req_set_fail(req);
	__io_req_complete(req, issue_flags, ret, 0);
	return 0;
}


static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_ring_ctx *ctx = req->ctx;
	bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
	struct io_uring_rsrc_update2 up;
	int ret;

	up.offset = req->rsrc_update.offset;
	up.data = req->rsrc_update.arg;
	up.nr = 0;
	up.tags = 0;
	up.resv = 0;
	up.resv2 = 0;

	io_ring_submit_lock(ctx, needs_lock);
	ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
					&up, req->rsrc_update.nr_args);
	io_ring_submit_unlock(ctx, needs_lock);

	if (ret < 0)
		req_set_fail(req);
	__io_req_complete(req, issue_flags, ret, 0);
	return 0;


static bool req_need_defer(struct io_kiocb *req, u32 seq)
{
	if (unlikely(req->flags & REQ_F_IO_DRAIN)) {
		struct io_ring_ctx *ctx = req->ctx;

		return seq + READ_ONCE(ctx->cq_extra) != ctx->cached_cq_tail;
	}

	return false;
}


static int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_connect *conn = &req->connect;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (sqe->ioprio || sqe->len || sqe->buf_index || sqe->rw_flags ||
	    sqe->splice_fd_in)
		return -EINVAL;

	conn->addr = u64_to_user_ptr(READ_ONCE(sqe->addr));
	conn->addr_len =  READ_ONCE(sqe->addr2);
	return 0;
}


static int io_mkdirat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_mkdir *mkd = &req->mkdir;
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = do_mkdirat(mkd->dfd, mkd->filename, mkd->mode);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	if (ret < 0)
		req_set_fail(req);
	io_req_complete(req, ret);
	return 0;
}


static __cold int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
{
	struct io_uring_task *tctx = current->io_uring;

	if (!tctx || !tctx->io_wq)
		return -EINVAL;

	return io_wq_cpu_affinity(tctx->io_wq, NULL);


static void io_poll_mark_cancelled(struct io_kiocb *req)
{
	atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs);


static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
{
	struct io_timeout_data *data = container_of(timer,
						struct io_timeout_data, timer);
	struct io_kiocb *req = data->req;
	struct io_ring_ctx *ctx = req->ctx;
	unsigned long flags;

	spin_lock_irqsave(&ctx->timeout_lock, flags);
	list_del_init(&req->timeout.list);
	atomic_set(&req->ctx->cq_timeouts,
		atomic_read(&req->ctx->cq_timeouts) + 1);
	spin_unlock_irqrestore(&ctx->timeout_lock, flags);

	if (!(data->flags & IORING_TIMEOUT_ETIME_SUCCESS))
		req_set_fail(req);

	req->result = -ETIME;
	req->io_task_work.func = io_req_task_complete;
	io_req_task_work_add(req, false);
	return HRTIMER_NORESTART;


			     struct timespec64 *ts, enum hrtimer_mode mode)
	__must_hold(&ctx->timeout_lock)
{
	struct io_kiocb *req = io_timeout_extract(ctx, user_data);
	struct io_timeout_data *data;

	if (IS_ERR(req))
		return PTR_ERR(req);

	req->timeout.off = 0; /* noseq */
	data = req->async_data;
	list_add_tail(&req->timeout.list, &ctx->timeout_list);
	hrtimer_init(&data->timer, io_timeout_get_clock(data), mode);
	data->timer.function = io_timeout_fn;
	hrtimer_start(&data->timer, timespec64_to_ktime(*ts), mode);
	return 0;


static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
{
	table->files = kvcalloc(nr_files, sizeof(table->files[0]),
				GFP_KERNEL_ACCOUNT);
	return !!table->files;


static void io_flush_apoll_cache(struct io_ring_ctx *ctx)
{
	struct async_poll *apoll;

	while (!list_empty(&ctx->apoll_cache)) {
		apoll = list_first_entry(&ctx->apoll_cache, struct async_poll,
						poll.wait.entry);
		list_del(&apoll->poll.wait.entry);
		kfree(apoll);
	}


static int io_unlinkat(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_unlink *un = &req->unlink;
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	if (un->flags & AT_REMOVEDIR)
		ret = do_rmdir(un->dfd, un->filename);
	else
		ret = do_unlinkat(un->dfd, un->filename);

	req->flags &= ~REQ_F_NEED_CLEANUP;
	if (ret < 0)
		req_set_fail(req);
	io_req_complete(req, ret);
	return 0;
}


static int io_statx_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	const char __user *path;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (req->flags & REQ_F_FIXED_FILE)
		return -EBADF;

	req->statx.dfd = READ_ONCE(sqe->fd);
	req->statx.mask = READ_ONCE(sqe->len);
	path = u64_to_user_ptr(READ_ONCE(sqe->addr));
	req->statx.buffer = u64_to_user_ptr(READ_ONCE(sqe->addr2));
	req->statx.flags = READ_ONCE(sqe->statx_flags);

	req->statx.filename = getname_flags(path,
					getname_statx_lookup_flags(req->statx.flags),
					NULL);

	if (IS_ERR(req->statx.filename)) {
		int ret = PTR_ERR(req->statx.filename);

		req->statx.filename = NULL;
		return ret;
	}

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}


static inline void io_queue_sqe(struct io_kiocb *req)
	__must_hold(&req->ctx->uring_lock)
{
	if (likely(!(req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL))))
		__io_queue_sqe(req);
	else
		io_queue_sqe_fallback(req);


static inline bool io_sqring_full(struct io_ring_ctx *ctx)
{
	struct io_rings *r = ctx->rings;

	return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;
}


static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
{
	if (!wq_list_empty(&ctx->submit_state.compl_reqs))
		__io_submit_flush_completions(ctx);
}


static noinline bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data,
				     s32 res, u32 cflags)
{
	ctx->cq_extra++;
	trace_io_uring_complete(ctx, NULL, user_data, res, cflags);
	return __io_fill_cqe(ctx, user_data, res, cflags);
}


static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref)
{
	struct io_rsrc_node *node = container_of(ref, struct io_rsrc_node, refs);
	struct io_ring_ctx *ctx = node->rsrc_data->ctx;
	unsigned long flags;
	bool first_add = false;
	unsigned long delay = HZ;

	spin_lock_irqsave(&ctx->rsrc_ref_lock, flags);
	node->done = true;

	/* if we are mid-quiesce then do not delay */
	if (node->rsrc_data->quiesce)
		delay = 0;

	while (!list_empty(&ctx->rsrc_ref_list)) {
		node = list_first_entry(&ctx->rsrc_ref_list,
					    struct io_rsrc_node, node);
		/* recycle ref nodes in order */
		if (!node->done)
			break;
		list_del(&node->node);
		first_add |= llist_add(&node->llist, &ctx->rsrc_put_llist);
	}
	spin_unlock_irqrestore(&ctx->rsrc_ref_lock, flags);

	if (first_add)
		mod_delayed_work(system_wq, &ctx->rsrc_put_work, delay);


static __cold 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->ref_comp);
}


static int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
				   unsigned size, unsigned type)
{
	struct io_uring_rsrc_update2 up;

	if (size != sizeof(up))
		return -EINVAL;
	if (copy_from_user(&up, arg, sizeof(up)))
		return -EFAULT;
	if (!up.nr || up.resv || up.resv2)
		return -EINVAL;
	return __io_register_rsrc_update(ctx, type, &up, up.nr);


static int io_refill_buffer_cache(struct io_ring_ctx *ctx)
{
	struct io_buffer *buf;
	struct page *page;
	int bufs_in_page;

	/*
	 * Completions that don't happen inline (eg not under uring_lock) will
	 * add to ->io_buffers_comp. If we don't have any free buffers, check
	 * the completion list and splice those entries first.
	 */
	if (!list_empty_careful(&ctx->io_buffers_comp)) {
		spin_lock(&ctx->completion_lock);
		if (!list_empty(&ctx->io_buffers_comp)) {
			list_splice_init(&ctx->io_buffers_comp,
						&ctx->io_buffers_cache);
			spin_unlock(&ctx->completion_lock);
			return 0;
		}
		spin_unlock(&ctx->completion_lock);
	}

	/*
	 * No free buffers and no completion entries either. Allocate a new
	 * page worth of buffer entries and add those to our freelist.
	 */
	page = alloc_page(GFP_KERNEL_ACCOUNT);
	if (!page)
		return -ENOMEM;

	list_add(&page->lru, &ctx->io_buffers_pages);

	buf = page_address(page);
	bufs_in_page = PAGE_SIZE / sizeof(*buf);
	while (bufs_in_page) {
		list_add_tail(&buf->list, &ctx->io_buffers_cache);
		buf++;
		bufs_in_page--;
	}

	return 0;
}


 */
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, nr_files;

	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;

	nr_files = 0;
	fpl->user = get_uid(current_user());
	for (i = 0; i < nr; i++) {
		struct file *file = io_file_from_index(ctx, i + offset);

		if (!file)
			continue;
		fpl->fp[nr_files] = get_file(file);
		unix_inflight(fpl->user, fpl->fp[nr_files]);
		nr_files++;
	}

	if (nr_files) {
		fpl->max = SCM_MAX_FD;
		fpl->count = nr_files;
		UNIXCB(skb).fp = fpl;
		skb->destructor = unix_destruct_scm;
		refcount_add(skb->truesize, &sk->sk_wmem_alloc);
		skb_queue_head(&sk->sk_receive_queue, skb);

		for (i = 0; i < nr; i++) {
			struct file *file = io_file_from_index(ctx, i + offset);

			if (file)
				fput(file);
		}
	} else {
		kfree_skb(skb);
		free_uid(fpl->user);
		kfree(fpl);
	}

	return 0;


static __cold int io_uring_alloc_task_context(struct task_struct *task,
					      struct io_ring_ctx *ctx)
{
	struct io_uring_task *tctx;
	int ret;

	tctx = kzalloc(sizeof(*tctx), GFP_KERNEL);
	if (unlikely(!tctx))
		return -ENOMEM;

	tctx->registered_rings = kcalloc(IO_RINGFD_REG_MAX,
					 sizeof(struct file *), GFP_KERNEL);
	if (unlikely(!tctx->registered_rings)) {
		kfree(tctx);
		return -ENOMEM;
	}

	ret = percpu_counter_init(&tctx->inflight, 0, GFP_KERNEL);
	if (unlikely(ret)) {
		kfree(tctx->registered_rings);
		kfree(tctx);
		return ret;
	}

	tctx->io_wq = io_init_wq_offload(ctx, task);
	if (IS_ERR(tctx->io_wq)) {
		ret = PTR_ERR(tctx->io_wq);
		percpu_counter_destroy(&tctx->inflight);
		kfree(tctx->registered_rings);
		kfree(tctx);
		return ret;
	}

	xa_init(&tctx->xa);
	init_waitqueue_head(&tctx->wait);
	atomic_set(&tctx->in_idle, 0);
	task->io_uring = tctx;
	spin_lock_init(&tctx->task_lock);
	INIT_WQ_LIST(&tctx->task_list);
	INIT_WQ_LIST(&tctx->prior_task_list);
	init_task_work(&tctx->task_work, tctx_task_work);
	return 0;


 */
static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
{
	struct file *file;
#if defined(CONFIG_UNIX)
	int ret;

	ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
				&ctx->ring_sock);
	if (ret)
		return ERR_PTR(ret);
#endif

	file = anon_inode_getfile_secure("[io_uring]", &io_uring_fops, ctx,
					 O_RDWR | O_CLOEXEC, NULL);
#if defined(CONFIG_UNIX)
	if (IS_ERR(file)) {
		sock_release(ctx->ring_sock);
		ctx->ring_sock = NULL;
	} else {
		ctx->ring_sock->file = file;
	}
#endif
	return file;


static void __io_req_find_next_prep(struct io_kiocb *req)
{
	struct io_ring_ctx *ctx = req->ctx;
	bool posted;

	spin_lock(&ctx->completion_lock);
	posted = io_disarm_next(req);
	if (posted)
		io_commit_cqring(ctx);
	spin_unlock(&ctx->completion_lock);
	if (posted)
		io_cqring_ev_posted(ctx);
}


static inline void io_req_put_rsrc(struct io_kiocb *req, struct io_ring_ctx *ctx)
{
	if (req->fixed_rsrc_refs)
		percpu_ref_put(req->fixed_rsrc_refs);
}


 */
static __cold void io_uring_cancel_generic(bool cancel_all,
					   struct io_sq_data *sqd)
{
	struct io_uring_task *tctx = current->io_uring;
	struct io_ring_ctx *ctx;
	s64 inflight;
	DEFINE_WAIT(wait);

	WARN_ON_ONCE(sqd && sqd->thread != current);

	if (!current->io_uring)
		return;
	if (tctx->io_wq)
		io_wq_exit_start(tctx->io_wq);

	atomic_inc(&tctx->in_idle);
	do {
		io_uring_drop_tctx_refs(current);
		/* read completions before cancelations */
		inflight = tctx_inflight(tctx, !cancel_all);
		if (!inflight)
			break;

		if (!sqd) {
			struct io_tctx_node *node;
			unsigned long index;

			xa_for_each(&tctx->xa, index, node) {
				/* sqpoll task will cancel all its requests */
				if (node->ctx->sq_data)
					continue;
				io_uring_try_cancel_requests(node->ctx, current,
							     cancel_all);
			}
		} else {
			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
				io_uring_try_cancel_requests(ctx, current,
							     cancel_all);
		}

		prepare_to_wait(&tctx->wait, &wait, TASK_INTERRUPTIBLE);
		io_run_task_work();
		io_uring_drop_tctx_refs(current);

		/*
		 * If we've seen completions, retry without waiting. This
		 * avoids a race where a completion comes in before we did
		 * prepare_to_wait().
		 */
		if (inflight == tctx_inflight(tctx, !cancel_all))
			schedule();
		finish_wait(&tctx->wait, &wait);
	} while (1);

	io_uring_clean_tctx(tctx);
	if (cancel_all) {
		/*
		 * We shouldn't run task_works after cancel, so just leave
		 * ->in_idle set for normal exit.
		 */
		atomic_dec(&tctx->in_idle);
		/* for exec all current's requests should be gone, kill tctx */
		__io_uring_free(current);
	}


static inline bool io_should_wake(struct io_wait_queue *iowq)
{
	struct io_ring_ctx *ctx = iowq->ctx;
	int dist = ctx->cached_cq_tail - (int) iowq->cq_tail;

	/*
	 * Wake up if we have enough events, or if a timeout occurred since we
	 * started waiting. For timeouts, we always want to return to userspace,
	 * regardless of event count.
	 */
	return dist >= 0 || atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;


static int io_madvise(struct io_kiocb *req, unsigned int issue_flags)
{
#if defined(CONFIG_ADVISE_SYSCALLS) && defined(CONFIG_MMU)
	struct io_madvise *ma = &req->madvise;
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	ret = do_madvise(current->mm, ma->addr, ma->len, ma->advice);
	if (ret < 0)
		req_set_fail(req);
	io_req_complete(req, ret);
	return 0;
#else
	return -EOPNOTSUPP;
#endif
}


static void io_iopoll_req_issued(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_ring_ctx *ctx = req->ctx;
	const bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;

	/* workqueue context doesn't hold uring_lock, grab it now */
	if (unlikely(needs_lock))
		mutex_lock(&ctx->uring_lock);

	/*
	 * 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 (wq_list_empty(&ctx->iopoll_list)) {
		ctx->poll_multi_queue = false;
	} else if (!ctx->poll_multi_queue) {
		struct io_kiocb *list_req;

		list_req = container_of(ctx->iopoll_list.first, struct io_kiocb,
					comp_list);
		if (list_req->file != req->file)
			ctx->poll_multi_queue = true;
	}

	/*
	 * For fast devices, IO may have already completed. If it has, add
	 * it to the front so we find it first.
	 */
	if (READ_ONCE(req->iopoll_completed))
		wq_list_add_head(&req->comp_list, &ctx->iopoll_list);
	else
		wq_list_add_tail(&req->comp_list, &ctx->iopoll_list);

	if (unlikely(needs_lock)) {
		/*
		 * If IORING_SETUP_SQPOLL is enabled, sqes are either handle
		 * in sq thread task context or in io worker task context. If
		 * current task context is sq thread, we don't need to check
		 * whether should wake up sq thread.
		 */
		if ((ctx->flags & IORING_SETUP_SQPOLL) &&
		    wq_has_sleeper(&ctx->sq_data->wait))
			wake_up(&ctx->sq_data->wait);

		mutex_unlock(&ctx->uring_lock);
	}
}


static bool io_resubmit_prep(struct io_kiocb *req)
{
	struct io_async_rw *rw = req->async_data;

	if (!req_has_async_data(req))
		return !io_req_prep_async(req);
	iov_iter_restore(&rw->s.iter, &rw->s.iter_state);
	return true;
}


static inline int io_import_iovec(int rw, struct io_kiocb *req,
				  struct iovec **iovec, struct io_rw_state *s,
				  unsigned int issue_flags)
{
	*iovec = __io_import_iovec(rw, req, s, issue_flags);
	if (unlikely(IS_ERR(*iovec)))
		return PTR_ERR(*iovec);

	iov_iter_save_state(&s->iter, &s->iter_state);
	return 0;
}


static int io_shutdown(struct io_kiocb *req, unsigned int issue_flags)
{
#if defined(CONFIG_NET)
	struct socket *sock;
	int ret;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	sock = sock_from_file(req->file);
	if (unlikely(!sock))
		return -ENOTSOCK;

	ret = __sys_shutdown_sock(sock, req->shutdown.how);
	if (ret < 0)
		req_set_fail(req);
	io_req_complete(req, ret);
	return 0;
#else
	return -EOPNOTSUPP;
#endif
}


 */
static __cold bool io_poll_remove_all(struct io_ring_ctx *ctx,
				      struct task_struct *tsk, bool cancel_all)
{
	struct hlist_node *tmp;
	struct io_kiocb *req;
	bool found = false;
	int i;

	spin_lock(&ctx->completion_lock);
	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
		struct hlist_head *list;

		list = &ctx->cancel_hash[i];
		hlist_for_each_entry_safe(req, tmp, list, hash_node) {
			if (io_match_task_safe(req, tsk, cancel_all)) {
				hlist_del_init(&req->hash_node);
				io_poll_cancel_req(req);
				found = true;
			}
		}
	}
	spin_unlock(&ctx->completion_lock);
	return found;


static inline void io_cqring_wake(struct io_ring_ctx *ctx)
{
	/*
	 * wake_up_all() may seem excessive, but io_wake_function() and
	 * io_should_wake() handle the termination of the loop and only
	 * wake as many waiters as we need to.
	 */
	if (wq_has_sleeper(&ctx->cq_wait))
		wake_up_all(&ctx->cq_wait);
}


static void io_destroy_buffers(struct io_ring_ctx *ctx)
{
	int i;

	for (i = 0; i < (1U << IO_BUFFERS_HASH_BITS); i++) {
		struct list_head *list = &ctx->io_buffers[i];

		while (!list_empty(list)) {
			struct io_buffer_list *bl;

			bl = list_first_entry(list, struct io_buffer_list, list);
			__io_remove_buffers(ctx, bl, -1U);
			list_del(&bl->list);
			kfree(bl);
		}
	}

	while (!list_empty(&ctx->io_buffers_pages)) {
		struct page *page;

		page = list_first_entry(&ctx->io_buffers_pages, struct page, lru);
		list_del_init(&page->lru);
		__free_page(page);
	}


static inline bool req_ref_inc_not_zero(struct io_kiocb *req)
{
	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
	return atomic_inc_not_zero(&req->refs);
}


static struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,
						 unsigned int bgid)
{
	struct list_head *hash_list;
	struct io_buffer_list *bl;

	hash_list = &ctx->io_buffers[hash_32(bgid, IO_BUFFERS_HASH_BITS)];
	list_for_each_entry(bl, hash_list, list)
		if (bl->bgid == bgid || bgid == -1U)
			return bl;

	return NULL;
}


static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_async_msghdr iomsg, *kmsg;
	struct io_sr_msg *sr = &req->sr_msg;
	struct socket *sock;
	struct io_buffer *kbuf;
	unsigned flags;
	int ret, min_ret = 0;
	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;

	sock = sock_from_file(req->file);
	if (unlikely(!sock))
		return -ENOTSOCK;

	if (req_has_async_data(req)) {
		kmsg = req->async_data;
	} else {
		ret = io_recvmsg_copy_hdr(req, &iomsg);
		if (ret)
			return ret;
		kmsg = &iomsg;
	}

	if (req->flags & REQ_F_BUFFER_SELECT) {
		kbuf = io_recv_buffer_select(req, issue_flags);
		if (IS_ERR(kbuf))
			return PTR_ERR(kbuf);
		kmsg->fast_iov[0].iov_base = u64_to_user_ptr(kbuf->addr);
		kmsg->fast_iov[0].iov_len = req->sr_msg.len;
		iov_iter_init(&kmsg->msg.msg_iter, READ, kmsg->fast_iov,
				1, req->sr_msg.len);
	}

	flags = req->sr_msg.msg_flags;
	if (force_nonblock)
		flags |= MSG_DONTWAIT;
	if (flags & MSG_WAITALL)
		min_ret = iov_iter_count(&kmsg->msg.msg_iter);

	ret = __sys_recvmsg_sock(sock, &kmsg->msg, req->sr_msg.umsg,
					kmsg->uaddr, flags);
	if (ret < min_ret) {
		if (ret == -EAGAIN && force_nonblock)
			return io_setup_async_msg(req, kmsg);
		if (ret == -ERESTARTSYS)
			ret = -EINTR;
		if (ret > 0 && io_net_retry(sock, flags)) {
			sr->done_io += ret;
			req->flags |= REQ_F_PARTIAL_IO;
			return io_setup_async_msg(req, kmsg);
		}
		req_set_fail(req);
	} else if ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
		req_set_fail(req);
	}

	/* fast path, check for non-NULL to avoid function call */
	if (kmsg->free_iov)
		kfree(kmsg->free_iov);
	req->flags &= ~REQ_F_NEED_CLEANUP;
	if (ret >= 0)
		ret += sr->done_io;
	else if (sr->done_io)
		ret = sr->done_io;
	__io_req_complete(req, issue_flags, ret, io_put_kbuf(req, issue_flags));
	return 0;
}


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;

	io_run_task_work();

	mutex_lock(&ctx->uring_lock);
	ret = __io_uring_register(ctx, opcode, arg, nr_args);
	mutex_unlock(&ctx->uring_lock);
	trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret);
out_fput:
	fdput(f);
	return ret;


static int io_mkdirat_prep(struct io_kiocb *req,
			    const struct io_uring_sqe *sqe)
{
	struct io_mkdir *mkd = &req->mkdir;
	const char __user *fname;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (sqe->ioprio || sqe->off || sqe->rw_flags || sqe->buf_index ||
	    sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->flags & REQ_F_FIXED_FILE))
		return -EBADF;

	mkd->dfd = READ_ONCE(sqe->fd);
	mkd->mode = READ_ONCE(sqe->len);

	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
	mkd->filename = getname(fname);
	if (IS_ERR(mkd->filename))
		return PTR_ERR(mkd->filename);

	req->flags |= REQ_F_NEED_CLEANUP;
	return 0;
}


static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
					struct task_struct *task)
{
	struct io_wq_hash *hash;
	struct io_wq_data data;
	unsigned int concurrency;

	mutex_lock(&ctx->uring_lock);
	hash = ctx->hash_map;
	if (!hash) {
		hash = kzalloc(sizeof(*hash), GFP_KERNEL);
		if (!hash) {
			mutex_unlock(&ctx->uring_lock);
			return ERR_PTR(-ENOMEM);
		}
		refcount_set(&hash->refs, 1);
		init_waitqueue_head(&hash->wait);
		ctx->hash_map = hash;
	}
	mutex_unlock(&ctx->uring_lock);

	data.hash = hash;
	data.task = task;
	data.free_work = io_wq_free_work;
	data.do_work = io_wq_submit_work;

	/* Do QD, or 4 * CPUS, whatever is smallest */
	concurrency = min(ctx->sq_entries, 4 * num_online_cpus());

	return io_wq_create(concurrency, &data);


static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
{
	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
	struct io_task_cancel *cancel = data;

	return io_match_task_safe(req, cancel->task, cancel->all);


static void __io_complete_rw(struct io_kiocb *req, long res,
			     unsigned int issue_flags)
{
	if (__io_complete_rw_common(req, res))
		return;
	__io_req_complete(req, issue_flags, req->result,
				io_put_kbuf(req, issue_flags));
}


	__must_hold(&req->ctx->timeout_lock)
{
	struct io_kiocb *link = req->link;

	if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
		struct io_timeout_data *io = link->async_data;

		io_remove_next_linked(req);
		link->timeout.head = NULL;
		if (hrtimer_try_to_cancel(&io->timer) != -1) {
			list_del(&link->timeout.list);
			/* leave REQ_F_CQE_SKIP to io_fill_cqe_req */
			io_fill_cqe_req(link, -ECANCELED, 0);
			io_put_req_deferred(link);
			return true;
		}
	}
	return false;
}


static inline void io_req_add_compl_list(struct io_kiocb *req)
{
	struct io_ring_ctx *ctx = req->ctx;
	struct io_submit_state *state = &ctx->submit_state;

	if (!(req->flags & REQ_F_CQE_SKIP))
		ctx->submit_state.flush_cqes = true;
	wq_list_add_tail(&req->comp_list, &state->compl_reqs);
}


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);

	__io_queue_proc(&pt->req->poll, pt, head,
			(struct io_poll_iocb **) &pt->req->async_data);


static __cold 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;

	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;


static void io_task_refs_refill(struct io_uring_task *tctx)
{
	unsigned int refill = -tctx->cached_refs + IO_TCTX_REFS_CACHE_NR;

	percpu_counter_add(&tctx->inflight, refill);
	refcount_add(refill, &current->usage);
	tctx->cached_refs += refill;
}


static __cold int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
			    unsigned int size, unsigned int type)
{
	struct io_uring_rsrc_register rr;

	/* keep it extendible */
	if (size != sizeof(rr))
		return -EINVAL;

	memset(&rr, 0, sizeof(rr));
	if (copy_from_user(&rr, arg, size))
		return -EFAULT;
	if (!rr.nr || rr.resv || rr.resv2)
		return -EINVAL;

	switch (type) {
	case IORING_RSRC_FILE:
		return io_sqe_files_register(ctx, u64_to_user_ptr(rr.data),
					     rr.nr, u64_to_user_ptr(rr.tags));
	case IORING_RSRC_BUFFER:
		return io_sqe_buffers_register(ctx, u64_to_user_ptr(rr.data),
					       rr.nr, u64_to_user_ptr(rr.tags));
	}
	return -EINVAL;


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;
		fallthrough;
	default:
		kiocb->ki_complete(kiocb, ret);
	}
}


static int __io_splice_prep(struct io_kiocb *req,
			    const struct io_uring_sqe *sqe)
{
	struct io_splice *sp = &req->splice;
	unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;

	sp->len = READ_ONCE(sqe->len);
	sp->flags = READ_ONCE(sqe->splice_flags);
	if (unlikely(sp->flags & ~valid_flags))
		return -EINVAL;
	sp->splice_fd_in = READ_ONCE(sqe->splice_fd_in);
	return 0;
}


static __cold void __io_free_req(struct io_kiocb *req)
{
	struct io_ring_ctx *ctx = req->ctx;

	io_req_put_rsrc(req, ctx);
	io_dismantle_req(req);
	io_put_task(req->task, 1);

	spin_lock(&ctx->completion_lock);
	wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
	ctx->locked_free_nr++;
	spin_unlock(&ctx->completion_lock);
}


static void io_eventfd_put(struct rcu_head *rcu)
{
	struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu);

	eventfd_ctx_put(ev_fd->cq_ev_fd);
	kfree(ev_fd);


static int io_connect(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_async_connect __io, *io;
	unsigned file_flags;
	int ret;
	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;

	if (req_has_async_data(req)) {
		io = req->async_data;
	} else {
		ret = move_addr_to_kernel(req->connect.addr,
						req->connect.addr_len,
						&__io.address);
		if (ret)
			goto out;
		io = &__io;
	}

	file_flags = force_nonblock ? O_NONBLOCK : 0;

	ret = __sys_connect_file(req->file, &io->address,
					req->connect.addr_len, file_flags);
	if ((ret == -EAGAIN || ret == -EINPROGRESS) && force_nonblock) {
		if (req_has_async_data(req))
			return -EAGAIN;
		if (io_alloc_async_data(req)) {
			ret = -ENOMEM;
			goto out;
		}
		memcpy(req->async_data, &__io, sizeof(__io));
		return -EAGAIN;
	}
	if (ret == -ERESTARTSYS)
		ret = -EINTR;
out:
	if (ret < 0)
		req_set_fail(req);
	__io_req_complete(req, issue_flags, ret, 0);
	return 0;
}


static int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
{
	struct io_wq_work_node *pos, *start, *prev;
	unsigned int poll_flags = BLK_POLL_NOSLEEP;
	DEFINE_IO_COMP_BATCH(iob);
	int nr_events = 0;

	/*
	 * Only spin for completions if we don't have multiple devices hanging
	 * off our complete list.
	 */
	if (ctx->poll_multi_queue || force_nonspin)
		poll_flags |= BLK_POLL_ONESHOT;

	wq_list_for_each(pos, start, &ctx->iopoll_list) {
		struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
		struct kiocb *kiocb = &req->rw.kiocb;
		int ret;

		/*
		 * Move completed and retryable entries to our local lists.
		 * If we find a request that requires polling, break out
		 * and complete those lists first, if we have entries there.
		 */
		if (READ_ONCE(req->iopoll_completed))
			break;

		ret = kiocb->ki_filp->f_op->iopoll(kiocb, &iob, poll_flags);
		if (unlikely(ret < 0))
			return ret;
		else if (ret)
			poll_flags |= BLK_POLL_ONESHOT;

		/* iopoll may have completed current req */
		if (!rq_list_empty(iob.req_list) ||
		    READ_ONCE(req->iopoll_completed))
			break;
	}

	if (!rq_list_empty(iob.req_list))
		iob.complete(&iob);
	else if (!pos)
		return 0;

	prev = start;
	wq_list_for_each_resume(pos, prev) {
		struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);

		/* order with io_complete_rw_iopoll(), e.g. ->result updates */
		if (!smp_load_acquire(&req->iopoll_completed))
			break;
		nr_events++;
		if (unlikely(req->flags & REQ_F_CQE_SKIP))
			continue;
		__io_fill_cqe_req(req, req->result, io_put_kbuf(req, 0));
	}

	if (unlikely(!nr_events))
		return 0;

	io_commit_cqring(ctx);
	io_cqring_ev_posted_iopoll(ctx);
	pos = start ? start->next : ctx->iopoll_list.first;
	wq_list_cut(&ctx->iopoll_list, prev, start);
	io_free_batch_list(ctx, pos);
	return nr_events;
}


static inline void io_req_set_refcount(struct io_kiocb *req)
{
	__io_req_set_refcount(req, 1);
}


static void *io_mem_alloc(size_t size)
{
	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;

	return (void *) __get_free_pages(gfp, get_order(size));


					   __u64 user_data)
	__must_hold(&ctx->timeout_lock)
{
	struct io_timeout_data *io;
	struct io_kiocb *req;
	bool found = false;

	list_for_each_entry(req, &ctx->timeout_list, timeout.list) {
		found = user_data == req->user_data;
		if (found)
			break;
	}
	if (!found)
		return ERR_PTR(-ENOENT);

	io = req->async_data;
	if (hrtimer_try_to_cancel(&io->timer) == -1)
		return ERR_PTR(-EALREADY);
	list_del_init(&req->timeout.list);
	return req;


static void io_prep_async_work(struct io_kiocb *req)
{
	const struct io_op_def *def = &io_op_defs[req->opcode];
	struct io_ring_ctx *ctx = req->ctx;

	if (!(req->flags & REQ_F_CREDS)) {
		req->flags |= REQ_F_CREDS;
		req->creds = get_current_cred();
	}

	req->work.list.next = NULL;
	req->work.flags = 0;
	if (req->flags & REQ_F_FORCE_ASYNC)
		req->work.flags |= IO_WQ_WORK_CONCURRENT;

	if (req->flags & REQ_F_ISREG) {
		if (def->hash_reg_file || (ctx->flags & IORING_SETUP_IOPOLL))
			io_wq_hash_work(&req->work, file_inode(req->file));
	} else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
		if (def->unbound_nonreg_file)
			req->work.flags |= IO_WQ_WORK_UNBOUND;
	}
}


static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
{
	if (WARN_ON_ONCE(!req->link))
		return NULL;

	req->flags &= ~REQ_F_ARM_LTIMEOUT;
	req->flags |= REQ_F_LINK_TIMEOUT;

	/* linked timeouts should have two refs once prep'ed */
	io_req_set_refcount(req);
	__io_req_set_refcount(req->link, 2);
	return req->link;
}


static int io_req_prep_async(struct io_kiocb *req)
{
	if (!io_op_defs[req->opcode].needs_async_setup)
		return 0;
	if (WARN_ON_ONCE(req_has_async_data(req)))
		return -EFAULT;
	if (io_alloc_async_data(req))
		return -EAGAIN;

	switch (req->opcode) {
	case IORING_OP_READV:
		return io_rw_prep_async(req, READ);
	case IORING_OP_WRITEV:
		return io_rw_prep_async(req, WRITE);
	case IORING_OP_SENDMSG:
		return io_sendmsg_prep_async(req);
	case IORING_OP_RECVMSG:
		return io_recvmsg_prep_async(req);
	case IORING_OP_CONNECT:
		return io_connect_prep_async(req);
	}
	printk_once(KERN_WARNING "io_uring: prep_async() bad opcode %d\n",
		    req->opcode);
	return -EFAULT;


static int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
{
	struct io_uring_task *tctx = current->io_uring;
	struct io_tctx_node *node;
	int ret;

	if (unlikely(!tctx)) {
		ret = io_uring_alloc_task_context(current, ctx);
		if (unlikely(ret))
			return ret;

		tctx = current->io_uring;
		if (ctx->iowq_limits_set) {
			unsigned int limits[2] = { ctx->iowq_limits[0],
						   ctx->iowq_limits[1], };

			ret = io_wq_max_workers(tctx->io_wq, limits);
			if (ret)
				return ret;
		}
	}
	if (!xa_load(&tctx->xa, (unsigned long)ctx)) {
		node = kmalloc(sizeof(*node), GFP_KERNEL);
		if (!node)
			return -ENOMEM;
		node->ctx = ctx;
		node->task = current;

		ret = xa_err(xa_store(&tctx->xa, (unsigned long)ctx,
					node, GFP_KERNEL));
		if (ret) {
			kfree(node);
			return ret;
		}

		mutex_lock(&ctx->uring_lock);
		list_add(&node->ctx_node, &ctx->tctx_list);
		mutex_unlock(&ctx->uring_lock);
	}
	tctx->last = ctx;
	return 0;


static inline void io_cqring_ev_posted(struct io_ring_ctx *ctx)
{
	if (unlikely(ctx->off_timeout_used || ctx->drain_active ||
		     ctx->has_evfd))
		__io_commit_cqring_flush(ctx);

	io_cqring_wake(ctx);
}


static inline bool req_has_async_data(struct io_kiocb *req)
{
	return req->flags & REQ_F_ASYNC_DATA;
}


static int io_epoll_ctl_prep(struct io_kiocb *req,
			     const struct io_uring_sqe *sqe)
{
#if defined(CONFIG_EPOLL)
	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;

	req->epoll.epfd = READ_ONCE(sqe->fd);
	req->epoll.op = READ_ONCE(sqe->len);
	req->epoll.fd = READ_ONCE(sqe->off);

	if (ep_op_has_event(req->epoll.op)) {
		struct epoll_event __user *ev;

		ev = u64_to_user_ptr(READ_ONCE(sqe->addr));
		if (copy_from_user(&req->epoll.event, ev, sizeof(*ev)))
			return -EFAULT;
	}

	return 0;
#else
	return -EOPNOTSUPP;
#endif
}


static __cold int io_probe(struct io_ring_ctx *ctx, void __user *arg,
			   unsigned nr_args)
{
	struct io_uring_probe *p;
	size_t size;
	int i, ret;

	size = struct_size(p, ops, nr_args);
	if (size == SIZE_MAX)
		return -EOVERFLOW;
	p = kzalloc(size, GFP_KERNEL);
	if (!p)
		return -ENOMEM;

	ret = -EFAULT;
	if (copy_from_user(p, arg, size))
		goto out;
	ret = -EINVAL;
	if (memchr_inv(p, 0, size))
		goto out;

	p->last_op = IORING_OP_LAST - 1;
	if (nr_args > IORING_OP_LAST)
		nr_args = IORING_OP_LAST;

	for (i = 0; i < nr_args; i++) {
		p->ops[i].op = i;
		if (!io_op_defs[i].not_supported)
			p->ops[i].flags = IO_URING_OP_SUPPORTED;
	}
	p->ops_len = i;

	ret = 0;
	if (copy_to_user(arg, p, size))
		ret = -EFAULT;
out:
	kfree(p);
	return ret;


static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
{
	struct io_rsrc_data *rsrc_data = ref_node->rsrc_data;
	struct io_ring_ctx *ctx = rsrc_data->ctx;
	struct io_rsrc_put *prsrc, *tmp;

	list_for_each_entry_safe(prsrc, tmp, &ref_node->rsrc_list, list) {
		list_del(&prsrc->list);

		if (prsrc->tag) {
			bool lock_ring = ctx->flags & IORING_SETUP_IOPOLL;

			io_ring_submit_lock(ctx, lock_ring);
			spin_lock(&ctx->completion_lock);
			io_fill_cqe_aux(ctx, prsrc->tag, 0, 0);
			io_commit_cqring(ctx);
			spin_unlock(&ctx->completion_lock);
			io_cqring_ev_posted(ctx);
			io_ring_submit_unlock(ctx, lock_ring);
		}

		rsrc_data->do_put(ctx, prsrc);
		kfree(prsrc);
	}

	io_rsrc_node_destroy(ref_node);
	if (atomic_dec_and_test(&rsrc_data->refs))
		complete(&rsrc_data->done);


static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
{
	if (unlikely(ctx->off_timeout_used || ctx->drain_active ||
		     ctx->has_evfd))
		__io_commit_cqring_flush(ctx);

	if (ctx->flags & IORING_SETUP_SQPOLL)
		io_cqring_wake(ctx);
}


void __io_uring_cancel(bool cancel_all)
{
	io_uring_cancel_generic(cancel_all, NULL);


	__must_hold(&ctx->uring_lock)
{
	struct task_struct *task = NULL;
	int task_refs = 0;

	do {
		struct io_kiocb *req = container_of(node, struct io_kiocb,
						    comp_list);

		if (unlikely(req->flags & REQ_F_REFCOUNT)) {
			node = req->comp_list.next;
			if (!req_ref_put_and_test(req))
				continue;
		}

		io_req_put_rsrc_locked(req, ctx);
		io_queue_next(req);
		io_dismantle_req(req);

		if (req->task != task) {
			if (task)
				io_put_task(task, task_refs);
			task = req->task;
			task_refs = 0;
		}
		task_refs++;
		node = req->comp_list.next;
		wq_stack_add_head(&req->comp_list, &ctx->submit_state.free_list);
	} while (node);

	if (task)
		io_put_task(task, task_refs);
}


 */
static int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_timeout_rem *tr = &req->timeout_rem;
	struct io_ring_ctx *ctx = req->ctx;
	int ret;

	if (!(req->timeout_rem.flags & IORING_TIMEOUT_UPDATE)) {
		spin_lock(&ctx->completion_lock);
		spin_lock_irq(&ctx->timeout_lock);
		ret = io_timeout_cancel(ctx, tr->addr);
		spin_unlock_irq(&ctx->timeout_lock);
		spin_unlock(&ctx->completion_lock);
	} else {
		enum hrtimer_mode mode = io_translate_timeout_mode(tr->flags);

		spin_lock_irq(&ctx->timeout_lock);
		if (tr->ltimeout)
			ret = io_linked_timeout_update(ctx, tr->addr, &tr->ts, mode);
		else
			ret = io_timeout_update(ctx, tr->addr, &tr->ts, mode);
		spin_unlock_irq(&ctx->timeout_lock);
	}

	if (ret < 0)
		req_set_fail(req);
	io_req_complete_post(req, ret, 0);
	return 0;


	__must_hold(&ctx->uring_lock)
{
	struct io_wq_work_node *node, *prev;
	struct io_submit_state *state = &ctx->submit_state;

	if (state->flush_cqes) {
		spin_lock(&ctx->completion_lock);
		wq_list_for_each(node, prev, &state->compl_reqs) {
			struct io_kiocb *req = container_of(node, struct io_kiocb,
						    comp_list);

			if (!(req->flags & REQ_F_CQE_SKIP))
				__io_fill_cqe_req(req, req->result, req->cflags);
			if ((req->flags & REQ_F_POLLED) && req->apoll) {
				struct async_poll *apoll = req->apoll;

				if (apoll->double_poll)
					kfree(apoll->double_poll);
				list_add(&apoll->poll.wait.entry,
						&ctx->apoll_cache);
				req->flags &= ~REQ_F_POLLED;
			}
		}

		io_commit_cqring(ctx);
		spin_unlock(&ctx->completion_lock);
		io_cqring_ev_posted(ctx);
		state->flush_cqes = false;
	}

	io_free_batch_list(ctx, state->compl_reqs.first);
	INIT_WQ_LIST(&state->compl_reqs);
}


static __cold void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
						struct task_struct *task,
						bool cancel_all)
{
	struct io_task_cancel cancel = { .task = task, .all = cancel_all, };
	struct io_uring_task *tctx = task ? task->io_uring : NULL;

	while (1) {
		enum io_wq_cancel cret;
		bool ret = false;

		if (!task) {
			ret |= io_uring_try_cancel_iowq(ctx);
		} else if (tctx && tctx->io_wq) {
			/*
			 * Cancels requests of all rings, not only @ctx, but
			 * it's fine as the task is in exit/exec.
			 */
			cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_task_cb,
					       &cancel, true);
			ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
		}

		/* SQPOLL thread does its own polling */
		if ((!(ctx->flags & IORING_SETUP_SQPOLL) && cancel_all) ||
		    (ctx->sq_data && ctx->sq_data->thread == current)) {
			while (!wq_list_empty(&ctx->iopoll_list)) {
				io_iopoll_try_reap_events(ctx);
				ret = true;
			}
		}

		ret |= io_cancel_defer_files(ctx, task, cancel_all);
		ret |= io_poll_remove_all(ctx, task, cancel_all);
		ret |= io_kill_timeouts(ctx, task, cancel_all);
		if (task)
			ret |= io_run_task_work();
		if (!ret)
			break;
		cond_resched();
	}


static void io_req_complete_fail_submit(struct io_kiocb *req)
{
	/*
	 * We don't submit, fail them all, for that replace hardlinks with
	 * normal links. Extra REQ_F_LINK is tolerated.
	 */
	req->flags &= ~REQ_F_HARDLINK;
	req->flags |= REQ_F_LINK;
	io_req_complete_failed(req, req->result);
}


static int io_rsrc_update_prep(struct io_kiocb *req,
				const struct io_uring_sqe *sqe)
{
	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
		return -EINVAL;
	if (sqe->ioprio || sqe->rw_flags || sqe->splice_fd_in)
		return -EINVAL;

	req->rsrc_update.offset = READ_ONCE(sqe->off);
	req->rsrc_update.nr_args = READ_ONCE(sqe->len);
	if (!req->rsrc_update.nr_args)
		return -EINVAL;
	req->rsrc_update.arg = READ_ONCE(sqe->addr);
	return 0;


static inline bool io_file_supports_nowait(struct io_kiocb *req)
{
	return req->flags & REQ_F_SUPPORT_NOWAIT;
}


static __cold void io_uring_clean_tctx(struct io_uring_task *tctx)
{
	struct io_wq *wq = tctx->io_wq;
	struct io_tctx_node *node;
	unsigned long index;

	xa_for_each(&tctx->xa, index, node) {
		io_uring_del_tctx_node(index);
		cond_resched();
	}
	if (wq) {
		/*
		 * Must be after io_uring_del_tctx_node() (removes nodes under
		 * uring_lock) to avoid race with io_uring_try_cancel_iowq().
		 */
		io_wq_put_and_exit(wq);
		tctx->io_wq = NULL;
	}


static int io_eventfd_unregister(struct io_ring_ctx *ctx)
{
	struct io_ev_fd *ev_fd;

	ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
					lockdep_is_held(&ctx->uring_lock));
	if (ev_fd) {
		ctx->has_evfd = false;
		rcu_assign_pointer(ctx->io_ev_fd, NULL);
		call_rcu(&ev_fd->rcu, io_eventfd_put);
		return 0;
	}

	return -ENXIO;


static void io_rsrc_data_free(struct io_rsrc_data *data)
{
	size_t size = data->nr * sizeof(data->tags[0][0]);

	if (data->tags)
		io_free_page_table((void **)data->tags, size);
	kfree(data);


static inline struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
{
	if (likely(!(req->flags & REQ_F_ARM_LTIMEOUT)))
		return NULL;
	return __io_prep_linked_timeout(req);
}


static __cold void io_uring_drop_tctx_refs(struct task_struct *task)
{
	struct io_uring_task *tctx = task->io_uring;
	unsigned int refs = tctx->cached_refs;

	if (refs) {
		tctx->cached_refs = 0;
		percpu_counter_sub(&tctx->inflight, refs);
		put_task_struct_many(task, refs);
	}
}


/* when returns >0, the caller should retry */
static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
					  struct io_wait_queue *iowq,
					  ktime_t timeout)
{
	int ret;

	/* make sure we run task_work before checking for signals */
	ret = io_run_task_work_sig();
	if (ret || io_should_wake(iowq))
		return ret;
	/* let the caller flush overflows, retry */
	if (test_bit(0, &ctx->check_cq_overflow))
		return 1;

	if (!schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS))
		return -ETIME;
	return 1;


static int io_close(struct io_kiocb *req, unsigned int issue_flags)
{
	struct files_struct *files = current->files;
	struct io_close *close = &req->close;
	struct fdtable *fdt;
	struct file *file = NULL;
	int ret = -EBADF;

	if (req->close.file_slot) {
		ret = io_close_fixed(req, issue_flags);
		goto err;
	}

	spin_lock(&files->file_lock);
	fdt = files_fdtable(files);
	if (close->fd >= fdt->max_fds) {
		spin_unlock(&files->file_lock);
		goto err;
	}
	file = fdt->fd[close->fd];
	if (!file || file->f_op == &io_uring_fops) {
		spin_unlock(&files->file_lock);
		file = NULL;
		goto err;
	}

	/* if the file has a flush method, be safe and punt to async */
	if (file->f_op->flush && (issue_flags & IO_URING_F_NONBLOCK)) {
		spin_unlock(&files->file_lock);
		return -EAGAIN;
	}

	ret = __close_fd_get_file(close->fd, &file);
	spin_unlock(&files->file_lock);
	if (ret < 0) {
		if (ret == -ENOENT)
			ret = -EBADF;
		goto err;
	}

	/* No ->flush() or already async, safely close from here */
	ret = filp_close(file, current->files);
err:
	if (ret < 0)
		req_set_fail(req);
	if (file)
		fput(file);
	__io_req_complete(req, issue_flags, ret, 0);
	return 0;
}


static int __io_arm_poll_handler(struct io_kiocb *req,
				 struct io_poll_iocb *poll,
				 struct io_poll_table *ipt, __poll_t mask)
{
	struct io_ring_ctx *ctx = req->ctx;
	int v;

	INIT_HLIST_NODE(&req->hash_node);
	io_init_poll_iocb(poll, mask, io_poll_wake);
	poll->file = req->file;

	ipt->pt._key = mask;
	ipt->req = req;
	ipt->error = 0;
	ipt->nr_entries = 0;

	/*
	 * Take the ownership to delay any tw execution up until we're done
	 * with poll arming. see io_poll_get_ownership().
	 */
	atomic_set(&req->poll_refs, 1);
	mask = vfs_poll(req->file, &ipt->pt) & poll->events;

	if (mask && (poll->events & EPOLLONESHOT)) {
		io_poll_remove_entries(req);
		/* no one else has access to the req, forget about the ref */
		return mask;
	}
	if (!mask && unlikely(ipt->error || !ipt->nr_entries)) {
		io_poll_remove_entries(req);
		if (!ipt->error)
			ipt->error = -EINVAL;
		return 0;
	}

	spin_lock(&ctx->completion_lock);
	io_poll_req_insert(req);
	spin_unlock(&ctx->completion_lock);

	if (mask) {
		/* can't multishot if failed, just queue the event we've got */
		if (unlikely(ipt->error || !ipt->nr_entries))
			poll->events |= EPOLLONESHOT;
		__io_poll_execute(req, mask, poll->events);
		return 0;
	}

	/*
	 * Release ownership. If someone tried to queue a tw while it was
	 * locked, kick it off for them.
	 */
	v = atomic_dec_return(&req->poll_refs);
	if (unlikely(v & IO_POLL_REF_MASK))
		__io_poll_execute(req, 0, poll->events);
	return 0;


static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
{
	io_sq_thread_finish(ctx);

	if (ctx->mm_account) {
		mmdrop(ctx->mm_account);
		ctx->mm_account = NULL;
	}

	io_rsrc_refs_drop(ctx);
	/* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
	io_wait_rsrc_data(ctx->buf_data);
	io_wait_rsrc_data(ctx->file_data);

	mutex_lock(&ctx->uring_lock);
	if (ctx->buf_data)
		__io_sqe_buffers_unregister(ctx);
	if (ctx->file_data)
		__io_sqe_files_unregister(ctx);
	if (ctx->rings)
		__io_cqring_overflow_flush(ctx, true);
	io_eventfd_unregister(ctx);
	io_flush_apoll_cache(ctx);
	mutex_unlock(&ctx->uring_lock);
	io_destroy_buffers(ctx);
	if (ctx->sq_creds)
		put_cred(ctx->sq_creds);

	/* there are no registered resources left, nobody uses it */
	if (ctx->rsrc_node)
		io_rsrc_node_destroy(ctx->rsrc_node);
	if (ctx->rsrc_backup_node)
		io_rsrc_node_destroy(ctx->rsrc_backup_node);
	flush_delayed_work(&ctx->rsrc_put_work);
	flush_delayed_work(&ctx->fallback_work);

	WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
	WARN_ON_ONCE(!llist_empty(&ctx->rsrc_put_llist));

#if defined(CONFIG_UNIX)
	if (ctx->ring_sock) {
		ctx->ring_sock->file = NULL; /* so that iput() is called */
		sock_release(ctx->ring_sock);
	}
#endif
	WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));

	io_mem_free(ctx->rings);
	io_mem_free(ctx->sq_sqes);

	percpu_ref_exit(&ctx->refs);
	free_uid(ctx->user);
	io_req_caches_free(ctx);
	if (ctx->hash_map)
		io_wq_put_hash(ctx->hash_map);
	kfree(ctx->cancel_hash);
	kfree(ctx->dummy_ubuf);
	kfree(ctx->io_buffers);
	kfree(ctx);


static inline void io_req_complete(struct io_kiocb *req, s32 res)
{
	__io_req_complete(req, 0, res, 0);
}


static inline void req_ref_get(struct io_kiocb *req)
{
	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
	atomic_inc(&req->refs);
}


static int io_fadvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	if (sqe->ioprio || sqe->buf_index || sqe->addr || sqe->splice_fd_in)
		return -EINVAL;
	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;

	req->fadvise.offset = READ_ONCE(sqe->off);
	req->fadvise.len = READ_ONCE(sqe->len);
	req->fadvise.advice = READ_ONCE(sqe->fadvise_advice);
	return 0;
}


static int io_get_ext_arg(unsigned flags, const void __user *argp, size_t *argsz,
			  struct __kernel_timespec __user **ts,
			  const sigset_t __user **sig)
{
	struct io_uring_getevents_arg arg;

	/*
	 * If EXT_ARG isn't set, then we have no timespec and the argp pointer
	 * is just a pointer to the sigset_t.
	 */
	if (!(flags & IORING_ENTER_EXT_ARG)) {
		*sig = (const sigset_t __user *) argp;
		*ts = NULL;
		return 0;
	}

	/*
	 * EXT_ARG is set - ensure we agree on the size of it and copy in our
	 * timespec and sigset_t pointers if good.
	 */
	if (*argsz != sizeof(arg))
		return -EINVAL;
	if (copy_from_user(&arg, argp, sizeof(arg)))
		return -EFAULT;
	if (arg.pad)
		return -EINVAL;
	*sig = u64_to_user_ptr(arg.sigmask);
	*argsz = arg.sigmask_sz;
	*ts = u64_to_user_ptr(arg.ts);
	return 0;


static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
				  struct io_uring_params __user *params)
{
	struct io_ring_ctx *ctx;
	struct file *file;
	int ret;

	if (!entries)
		return -EINVAL;
	if (entries > IORING_MAX_ENTRIES) {
		if (!(p->flags & IORING_SETUP_CLAMP))
			return -EINVAL;
		entries = IORING_MAX_ENTRIES;
	}

	/*
	 * 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. If the application has
	 * set IORING_SETUP_CQSIZE, it will have passed in the desired number
	 * of CQ ring entries manually.
	 */
	p->sq_entries = roundup_pow_of_two(entries);
	if (p->flags & IORING_SETUP_CQSIZE) {
		/*
		 * If IORING_SETUP_CQSIZE is set, we do the same roundup
		 * to a power-of-two, if it isn't already. We do NOT impose
		 * any cq vs sq ring sizing.
		 */
		if (!p->cq_entries)
			return -EINVAL;
		if (p->cq_entries > IORING_MAX_CQ_ENTRIES) {
			if (!(p->flags & IORING_SETUP_CLAMP))
				return -EINVAL;
			p->cq_entries = IORING_MAX_CQ_ENTRIES;
		}
		p->cq_entries = roundup_pow_of_two(p->cq_entries);
		if (p->cq_entries < p->sq_entries)
			return -EINVAL;
	} else {
		p->cq_entries = 2 * p->sq_entries;
	}

	ctx = io_ring_ctx_alloc(p);
	if (!ctx)
		return -ENOMEM;
	ctx->compat = in_compat_syscall();
	if (!capable(CAP_IPC_LOCK))
		ctx->user = get_uid(current_user());

	/*
	 * This is just grabbed for accounting purposes. When a process exits,
	 * the mm is exited and dropped before the files, hence we need to hang
	 * on to this mm purely for the purposes of being able to unaccount
	 * memory (locked/pinned vm). It's not used for anything else.
	 */
	mmgrab(current->mm);
	ctx->mm_account = current->mm;

	ret = io_allocate_scq_urings(ctx, p);
	if (ret)
		goto err;

	ret = io_sq_offload_create(ctx, p);
	if (ret)
		goto err;
	/* always set a rsrc node */
	ret = io_rsrc_node_switch_start(ctx);
	if (ret)
		goto err;
	io_rsrc_node_switch(ctx, NULL);

	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);
	p->cq_off.flags = offsetof(struct io_rings, cq_flags);

	p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |
			IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |
			IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL |
			IORING_FEAT_POLL_32BITS | IORING_FEAT_SQPOLL_NONFIXED |
			IORING_FEAT_EXT_ARG | IORING_FEAT_NATIVE_WORKERS |
			IORING_FEAT_RSRC_TAGS | IORING_FEAT_CQE_SKIP |
			IORING_FEAT_LINKED_FILE;

	if (copy_to_user(params, p, sizeof(*p))) {
		ret = -EFAULT;
		goto err;
	}

	file = io_uring_get_file(ctx);
	if (IS_ERR(file)) {
		ret = PTR_ERR(file);
		goto err;
	}

	/*
	 * Install ring fd as the very last thing, so we don't risk someone
	 * having closed it before we finish setup
	 */
	ret = io_uring_install_fd(ctx, file);
	if (ret < 0) {
		/* fput will clean it up */
		fput(file);
		return ret;
	}

	trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags);
	return ret;
err:
	io_ring_ctx_wait_and_kill(ctx);
	return ret;


static ssize_t io_compat_import(struct io_kiocb *req, struct iovec *iov,
				unsigned int issue_flags)
{
	struct compat_iovec __user *uiov;
	compat_ssize_t clen;
	void __user *buf;
	ssize_t len;

	uiov = u64_to_user_ptr(req->rw.addr);
	if (!access_ok(uiov, sizeof(*uiov)))
		return -EFAULT;
	if (__get_user(clen, &uiov->iov_len))
		return -EFAULT;
	if (clen < 0)
		return -EINVAL;

	len = clen;
	buf = io_rw_buffer_select(req, &len, issue_flags);
	if (IS_ERR(buf))
		return PTR_ERR(buf);
	iov[0].iov_base = buf;
	iov[0].iov_len = (compat_size_t) len;
	return 0;
}


static int io_tee(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_splice *sp = &req->splice;
	struct file *out = sp->file_out;
	unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
	struct file *in;
	long ret = 0;

	if (issue_flags & IO_URING_F_NONBLOCK)
		return -EAGAIN;

	if (sp->flags & SPLICE_F_FD_IN_FIXED)
		in = io_file_get_fixed(req, sp->splice_fd_in, issue_flags);
	else
		in = io_file_get_normal(req, sp->splice_fd_in);
	if (!in) {
		ret = -EBADF;
		goto done;
	}

	if (sp->len)
		ret = do_tee(in, out, sp->len, flags);

	if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
		io_put_file(in);
done:
	if (ret != sp->len)
		req_set_fail(req);
	io_req_complete(req, ret);
	return 0;
}


static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
{
	struct kiocb *kiocb = &req->rw.kiocb;

	if (kiocb->ki_pos != -1)
		return &kiocb->ki_pos;

	if (!(req->file->f_mode & FMODE_STREAM)) {
		req->flags |= REQ_F_CUR_POS;
		kiocb->ki_pos = req->file->f_pos;
		return &kiocb->ki_pos;
	}

	kiocb->ki_pos = 0;
	return NULL;
}


static void io_free_req_work(struct io_kiocb *req, bool *locked)
{
	io_free_req(req);
}


static inline bool __io_fill_cqe(struct io_ring_ctx *ctx, u64 user_data,
				 s32 res, u32 cflags)
{
	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_cqe(ctx);
	if (likely(cqe)) {
		WRITE_ONCE(cqe->user_data, user_data);
		WRITE_ONCE(cqe->res, res);
		WRITE_ONCE(cqe->flags, cflags);
		return true;
	}
	return io_cqring_event_overflow(ctx, user_data, res, cflags);
}


static inline void io_poll_execute(struct io_kiocb *req, int res, int events)
{
	if (io_poll_get_ownership(req))
		__io_poll_execute(req, res, events);


static void tctx_task_work(struct callback_head *cb)
{
	bool uring_locked = false;
	struct io_ring_ctx *ctx = NULL;
	struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
						  task_work);

	while (1) {
		struct io_wq_work_node *node1, *node2;

		if (!tctx->task_list.first &&
		    !tctx->prior_task_list.first && uring_locked)
			io_submit_flush_completions(ctx);

		spin_lock_irq(&tctx->task_lock);
		node1 = tctx->prior_task_list.first;
		node2 = tctx->task_list.first;
		INIT_WQ_LIST(&tctx->task_list);
		INIT_WQ_LIST(&tctx->prior_task_list);
		if (!node2 && !node1)
			tctx->task_running = false;
		spin_unlock_irq(&tctx->task_lock);
		if (!node2 && !node1)
			break;

		if (node1)
			handle_prev_tw_list(node1, &ctx, &uring_locked);

		if (node2)
			handle_tw_list(node2, &ctx, &uring_locked);
		cond_resched();
	}

	ctx_flush_and_put(ctx, &uring_locked);

	/* relaxed read is enough as only the task itself sets ->in_idle */
	if (unlikely(atomic_read(&tctx->in_idle)))
		io_uring_drop_tctx_refs(current);
}


static inline void io_get_task_refs(int nr)
{
	struct io_uring_task *tctx = current->io_uring;

	tctx->cached_refs -= nr;
	if (unlikely(tctx->cached_refs < 0))
		io_task_refs_refill(tctx);
}


static int io_write(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_rw_state __s, *s = &__s;
	struct iovec *iovec;
	struct kiocb *kiocb = &req->rw.kiocb;
	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
	ssize_t ret, ret2;
	loff_t *ppos;

	if (!req_has_async_data(req)) {
		ret = io_import_iovec(WRITE, req, &iovec, s, issue_flags);
		if (unlikely(ret < 0))
			return ret;
	} else {
		struct io_async_rw *rw = req->async_data;

		s = &rw->s;
		iov_iter_restore(&s->iter, &s->iter_state);
		iovec = NULL;
	}
	ret = io_rw_init_file(req, FMODE_WRITE);
	if (unlikely(ret)) {
		kfree(iovec);
		return ret;
	}
	req->result = iov_iter_count(&s->iter);

	if (force_nonblock) {
		/* If the file doesn't support async, just async punt */
		if (unlikely(!io_file_supports_nowait(req)))
			goto copy_iov;

		/* file path doesn't support NOWAIT for non-direct_IO */
		if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT) &&
		    (req->flags & REQ_F_ISREG))
			goto copy_iov;

		kiocb->ki_flags |= IOCB_NOWAIT;
	} else {
		/* Ensure we clear previously set non-block flag */
		kiocb->ki_flags &= ~IOCB_NOWAIT;
	}

	ppos = io_kiocb_update_pos(req);

	ret = rw_verify_area(WRITE, req->file, ppos, req->result);
	if (unlikely(ret))
		goto out_free;

	/*
	 * 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(req->file)->i_sb);
		__sb_writers_release(file_inode(req->file)->i_sb,
					SB_FREEZE_WRITE);
	}
	kiocb->ki_flags |= IOCB_WRITE;

	if (likely(req->file->f_op->write_iter))
		ret2 = call_write_iter(req->file, kiocb, &s->iter);
	else if (req->file->f_op->write)
		ret2 = loop_rw_iter(WRITE, req, &s->iter);
	else
		ret2 = -EINVAL;

	if (req->flags & REQ_F_REISSUE) {
		req->flags &= ~REQ_F_REISSUE;
		ret2 = -EAGAIN;
	}

	/*
	 * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
	 * retry them without IOCB_NOWAIT.
	 */
	if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT))
		ret2 = -EAGAIN;
	/* no retry on NONBLOCK nor RWF_NOWAIT */
	if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
		goto done;
	if (!force_nonblock || ret2 != -EAGAIN) {
		/* IOPOLL retry should happen for io-wq threads */
		if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
			goto copy_iov;
done:
		kiocb_done(req, ret2, issue_flags);
	} else {
copy_iov:
		iov_iter_restore(&s->iter, &s->iter_state);
		ret = io_setup_async_rw(req, iovec, s, false);
		return ret ?: -EAGAIN;
	}
out_free:
	/* it's reportedly faster than delegating the null check to kfree() */
	if (iovec)
		kfree(iovec);
	return ret;
}


static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
{
	struct io_ring_ctx *ctx;
	int i, hash_bits;

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
		return NULL;

	/*
	 * Use 5 bits less than the max cq entries, that should give us around
	 * 32 entries per hash list if totally full and uniformly spread.
	 */
	hash_bits = ilog2(p->cq_entries);
	hash_bits -= 5;
	if (hash_bits <= 0)
		hash_bits = 1;
	ctx->cancel_hash_bits = hash_bits;
	ctx->cancel_hash = kmalloc((1U << hash_bits) * sizeof(struct hlist_head),
					GFP_KERNEL);
	if (!ctx->cancel_hash)
		goto err;
	__hash_init(ctx->cancel_hash, 1U << hash_bits);

	ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
	if (!ctx->dummy_ubuf)
		goto err;
	/* set invalid range, so io_import_fixed() fails meeting it */
	ctx->dummy_ubuf->ubuf = -1UL;

	ctx->io_buffers = kcalloc(1U << IO_BUFFERS_HASH_BITS,
					sizeof(struct list_head), GFP_KERNEL);
	if (!ctx->io_buffers)
		goto err;
	for (i = 0; i < (1U << IO_BUFFERS_HASH_BITS); i++)
		INIT_LIST_HEAD(&ctx->io_buffers[i]);

	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL))
		goto err;

	ctx->flags = p->flags;
	init_waitqueue_head(&ctx->sqo_sq_wait);
	INIT_LIST_HEAD(&ctx->sqd_list);
	INIT_LIST_HEAD(&ctx->cq_overflow_list);
	INIT_LIST_HEAD(&ctx->io_buffers_cache);
	INIT_LIST_HEAD(&ctx->apoll_cache);
	init_completion(&ctx->ref_comp);
	xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
	mutex_init(&ctx->uring_lock);
	init_waitqueue_head(&ctx->cq_wait);
	spin_lock_init(&ctx->completion_lock);
	spin_lock_init(&ctx->timeout_lock);
	INIT_WQ_LIST(&ctx->iopoll_list);
	INIT_LIST_HEAD(&ctx->io_buffers_pages);
	INIT_LIST_HEAD(&ctx->io_buffers_comp);
	INIT_LIST_HEAD(&ctx->defer_list);
	INIT_LIST_HEAD(&ctx->timeout_list);
	INIT_LIST_HEAD(&ctx->ltimeout_list);
	spin_lock_init(&ctx->rsrc_ref_lock);
	INIT_LIST_HEAD(&ctx->rsrc_ref_list);
	INIT_DELAYED_WORK(&ctx->rsrc_put_work, io_rsrc_put_work);
	init_llist_head(&ctx->rsrc_put_llist);
	INIT_LIST_HEAD(&ctx->tctx_list);
	ctx->submit_state.free_list.next = NULL;
	INIT_WQ_LIST(&ctx->locked_free_list);
	INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
	INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
	return ctx;
err:
	kfree(ctx->dummy_ubuf);
	kfree(ctx->cancel_hash);
	kfree(ctx->io_buffers);
	kfree(ctx);
	return NULL;
}


static int io_timeout_remove_prep(struct io_kiocb *req,
				  const struct io_uring_sqe *sqe)
{
	struct io_timeout_rem *tr = &req->timeout_rem;

	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
		return -EINVAL;
	if (sqe->ioprio || sqe->buf_index || sqe->len || sqe->splice_fd_in)
		return -EINVAL;

	tr->ltimeout = false;
	tr->addr = READ_ONCE(sqe->addr);
	tr->flags = READ_ONCE(sqe->timeout_flags);
	if (tr->flags & IORING_TIMEOUT_UPDATE_MASK) {
		if (hweight32(tr->flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
			return -EINVAL;
		if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
			tr->ltimeout = true;
		if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK|IORING_TIMEOUT_ABS))
			return -EINVAL;
		if (get_timespec64(&tr->ts, u64_to_user_ptr(sqe->addr2)))
			return -EFAULT;
		if (tr->ts.tv_sec < 0 || tr->ts.tv_nsec < 0)
			return -EINVAL;
	} else if (tr->flags) {
		/* timeout removal doesn't support flags */
		return -EINVAL;
	}

	return 0;


		       const struct io_uring_sqe *sqe)
	__must_hold(&ctx->uring_lock)
{
	unsigned int sqe_flags;
	int personality;
	u8 opcode;

	/* req is partially pre-initialised, see io_preinit_req() */
	req->opcode = opcode = READ_ONCE(sqe->opcode);
	/* same numerical values with corresponding REQ_F_*, safe to copy */
	req->flags = sqe_flags = READ_ONCE(sqe->flags);
	req->user_data = READ_ONCE(sqe->user_data);
	req->file = NULL;
	req->fixed_rsrc_refs = NULL;
	req->task = current;

	if (unlikely(opcode >= IORING_OP_LAST)) {
		req->opcode = 0;
		return -EINVAL;
	}
	if (unlikely(sqe_flags & ~SQE_COMMON_FLAGS)) {
		/* enforce forwards compatibility on users */
		if (sqe_flags & ~SQE_VALID_FLAGS)
			return -EINVAL;
		if ((sqe_flags & IOSQE_BUFFER_SELECT) &&
		    !io_op_defs[opcode].buffer_select)
			return -EOPNOTSUPP;
		if (sqe_flags & IOSQE_CQE_SKIP_SUCCESS)
			ctx->drain_disabled = true;
		if (sqe_flags & IOSQE_IO_DRAIN) {
			if (ctx->drain_disabled)
				return -EOPNOTSUPP;
			io_init_req_drain(req);
		}
	}
	if (unlikely(ctx->restricted || ctx->drain_active || ctx->drain_next)) {
		if (ctx->restricted && !io_check_restriction(ctx, req, sqe_flags))
			return -EACCES;
		/* knock it to the slow queue path, will be drained there */
		if (ctx->drain_active)
			req->flags |= REQ_F_FORCE_ASYNC;
		/* if there is no link, we're at "next" request and need to drain */
		if (unlikely(ctx->drain_next) && !ctx->submit_state.link.head) {
			ctx->drain_next = false;
			ctx->drain_active = true;
			req->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
		}
	}

	if (io_op_defs[opcode].needs_file) {
		struct io_submit_state *state = &ctx->submit_state;

		req->fd = READ_ONCE(sqe->fd);

		/*
		 * Plug now if we have more than 2 IO left after this, and the
		 * target is potentially a read/write to block based storage.
		 */
		if (state->need_plug && io_op_defs[opcode].plug) {
			state->plug_started = true;
			state->need_plug = false;
			blk_start_plug_nr_ios(&state->plug, state->submit_nr);
		}
	}

	personality = READ_ONCE(sqe->personality);
	if (personality) {
		int ret;

		req->creds = xa_load(&ctx->personalities, personality);
		if (!req->creds)
			return -EINVAL;
		get_cred(req->creds);
		ret = security_uring_override_creds(req->creds);
		if (ret) {
			put_cred(req->creds);
			return ret;
		}
		req->flags |= REQ_F_CREDS;
	}

	return io_req_prep(req, sqe);


static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
{
	struct io_timeout_data *data = container_of(timer,
						struct io_timeout_data, timer);
	struct io_kiocb *prev, *req = data->req;
	struct io_ring_ctx *ctx = req->ctx;
	unsigned long flags;

	spin_lock_irqsave(&ctx->timeout_lock, flags);
	prev = req->timeout.head;
	req->timeout.head = NULL;

	/*
	 * We don't expect the list to be empty, that will only happen if we
	 * race with the completion of the linked work.
	 */
	if (prev) {
		io_remove_next_linked(prev);
		if (!req_ref_inc_not_zero(prev))
			prev = NULL;
	}
	list_del(&req->timeout.list);
	req->timeout.prev = prev;
	spin_unlock_irqrestore(&ctx->timeout_lock, flags);

	req->io_task_work.func = io_req_task_link_timeout;
	io_req_task_work_add(req, false);
	return HRTIMER_NORESTART;


static int io_shutdown_prep(struct io_kiocb *req,
			    const struct io_uring_sqe *sqe)
{
#if defined(CONFIG_NET)
	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
	if (unlikely(sqe->ioprio || sqe->off || sqe->addr || sqe->rw_flags ||
		     sqe->buf_index || sqe->splice_fd_in))
		return -EINVAL;

	req->shutdown.how = READ_ONCE(sqe->len);
	return 0;
#else
	return -EOPNOTSUPP;
#endif
}


static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
			void *key)
{
	struct io_kiocb *req = wqe_to_req(wait);
	struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
						 wait);
	__poll_t mask = key_to_poll(key);

	if (unlikely(mask & POLLFREE)) {
		io_poll_mark_cancelled(req);
		/* we have to kick tw in case it's not already */
		io_poll_execute(req, 0, poll->events);

		/*
		 * If the waitqueue is being freed early but someone is already
		 * holds ownership over it, we have to tear down the request as
		 * best we can. That means immediately removing the request from
		 * its waitqueue and preventing all further accesses to the
		 * waitqueue via the request.
		 */
		list_del_init(&poll->wait.entry);

		/*
		 * Careful: this *must* be the last step, since as soon
		 * as req->head is NULL'ed out, the request can be
		 * completed and freed, since aio_poll_complete_work()
		 * will no longer need to take the waitqueue lock.
		 */
		smp_store_release(&poll->head, NULL);
		return 1;
	}

	/* for instances that support it check for an event match first */
	if (mask && !(mask & poll->events))
		return 0;

	if (io_poll_get_ownership(req)) {
		/* optional, saves extra locking for removal in tw handler */
		if (mask && poll->events & EPOLLONESHOT) {
			list_del_init(&poll->wait.entry);
			poll->head = NULL;
			if (wqe_is_double(wait))
				req->flags &= ~REQ_F_DOUBLE_POLL;
			else
				req->flags &= ~REQ_F_SINGLE_POLL;
		}
		__io_poll_execute(req, mask, poll->events);
	}
	return 1;


void io_uring_unreg_ringfd(void)
{
	struct io_uring_task *tctx = current->io_uring;
	int i;

	for (i = 0; i < IO_RINGFD_REG_MAX; i++) {
		if (tctx->registered_rings[i]) {
			fput(tctx->registered_rings[i]);
			tctx->registered_rings[i] = NULL;
		}
	}


	__must_hold(&ctx->completion_lock)
	__must_hold(&ctx->timeout_lock)
{
	struct io_kiocb *req = io_timeout_extract(ctx, user_data);

	if (IS_ERR(req))
		return PTR_ERR(req);
	io_req_task_queue_fail(req, -ECANCELED);
	return 0;


static __cold int io_rsrc_data_alloc(struct io_ring_ctx *ctx, rsrc_put_fn *do_put,
				     u64 __user *utags, unsigned nr,
				     struct io_rsrc_data **pdata)
{
	struct io_rsrc_data *data;
	int ret = -ENOMEM;
	unsigned i;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;
	data->tags = (u64 **)io_alloc_page_table(nr * sizeof(data->tags[0][0]));
	if (!data->tags) {
		kfree(data);
		return -ENOMEM;
	}

	data->nr = nr;
	data->ctx = ctx;
	data->do_put = do_put;
	if (utags) {
		ret = -EFAULT;
		for (i = 0; i < nr; i++) {
			u64 *tag_slot = io_get_tag_slot(data, i);

			if (copy_from_user(tag_slot, &utags[i],
					   sizeof(*tag_slot)))
				goto fail;
		}
	}

	atomic_set(&data->refs, 1);
	init_completion(&data->done);
	*pdata = data;
	return 0;
fail:
	io_rsrc_data_free(data);
	return ret;