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https://github.com/torvalds/linux
synced 2024-09-06 09:51:23 +00:00
![Jens Axboe](/assets/img/avatar_default.png)
Our provided buffer interface only allows selection of a single buffer. Add an API that allows getting/peeking multiple buffers at the same time. This is only implemented for the ring provided buffers. It could be added for the legacy provided buffers as well, but since it's strongly encouraged to use the new interface, let's keep it simpler and just provide it for the new API. The legacy interface will always just select a single buffer. There are two new main functions: io_buffers_select(), which selects up as many buffers as it can. The caller supplies the iovec array, and io_buffers_select() may allocate a bigger array if the 'out_len' being passed in is non-zero and bigger than what fits in the provided iovec. Buffers grabbed with this helper are permanently assigned. io_buffers_peek(), which works like io_buffers_select(), except they can be recycled, if needed. Callers using either of these functions should call io_put_kbufs() rather than io_put_kbuf() at completion time. The peek interface must be called with the ctx locked from peek to completion. This add a bit state for the request: - REQ_F_BUFFERS_COMMIT, which means that the the buffers have been peeked and should be committed to the buffer ring head when they are put as part of completion. Prior to this, req->buf_list was cleared to NULL when committed. Signed-off-by: Jens Axboe <axboe@kernel.dk>
826 lines
20 KiB
C
826 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/namei.h>
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#include <linux/poll.h>
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#include <linux/vmalloc.h>
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#include <linux/io_uring.h>
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#include <uapi/linux/io_uring.h>
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#include "io_uring.h"
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#include "opdef.h"
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#include "kbuf.h"
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#include "memmap.h"
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/* BIDs are addressed by a 16-bit field in a CQE */
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#define MAX_BIDS_PER_BGID (1 << 16)
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struct kmem_cache *io_buf_cachep;
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struct io_provide_buf {
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struct file *file;
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__u64 addr;
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__u32 len;
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__u32 bgid;
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__u32 nbufs;
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__u16 bid;
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};
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static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,
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unsigned int bgid)
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{
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lockdep_assert_held(&ctx->uring_lock);
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return xa_load(&ctx->io_bl_xa, bgid);
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}
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static int io_buffer_add_list(struct io_ring_ctx *ctx,
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struct io_buffer_list *bl, unsigned int bgid)
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{
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/*
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* Store buffer group ID and finally mark the list as visible.
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* The normal lookup doesn't care about the visibility as we're
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* always under the ->uring_lock, but the RCU lookup from mmap does.
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*/
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bl->bgid = bgid;
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atomic_set(&bl->refs, 1);
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return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL));
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}
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bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags)
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct io_buffer_list *bl;
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struct io_buffer *buf;
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io_ring_submit_lock(ctx, issue_flags);
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buf = req->kbuf;
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bl = io_buffer_get_list(ctx, buf->bgid);
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list_add(&buf->list, &bl->buf_list);
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req->flags &= ~REQ_F_BUFFER_SELECTED;
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req->buf_index = buf->bgid;
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io_ring_submit_unlock(ctx, issue_flags);
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return true;
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}
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void __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags)
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{
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/*
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* We can add this buffer back to two lists:
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*
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* 1) The io_buffers_cache list. This one is protected by the
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* ctx->uring_lock. If we already hold this lock, add back to this
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* list as we can grab it from issue as well.
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* 2) The io_buffers_comp list. This one is protected by the
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* ctx->completion_lock.
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*
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* We migrate buffers from the comp_list to the issue cache list
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* when we need one.
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*/
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if (issue_flags & IO_URING_F_UNLOCKED) {
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struct io_ring_ctx *ctx = req->ctx;
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spin_lock(&ctx->completion_lock);
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__io_put_kbuf_list(req, &ctx->io_buffers_comp);
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spin_unlock(&ctx->completion_lock);
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} else {
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lockdep_assert_held(&req->ctx->uring_lock);
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__io_put_kbuf_list(req, &req->ctx->io_buffers_cache);
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}
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}
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static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len,
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struct io_buffer_list *bl)
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{
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if (!list_empty(&bl->buf_list)) {
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struct io_buffer *kbuf;
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kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list);
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list_del(&kbuf->list);
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if (*len == 0 || *len > kbuf->len)
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*len = kbuf->len;
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if (list_empty(&bl->buf_list))
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req->flags |= REQ_F_BL_EMPTY;
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req->flags |= REQ_F_BUFFER_SELECTED;
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req->kbuf = kbuf;
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req->buf_index = kbuf->bid;
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return u64_to_user_ptr(kbuf->addr);
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}
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return NULL;
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}
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static int io_provided_buffers_select(struct io_kiocb *req, size_t *len,
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struct io_buffer_list *bl,
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struct iovec *iov)
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{
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void __user *buf;
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buf = io_provided_buffer_select(req, len, bl);
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if (unlikely(!buf))
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return -ENOBUFS;
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iov[0].iov_base = buf;
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iov[0].iov_len = *len;
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return 0;
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}
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static struct io_uring_buf *io_ring_head_to_buf(struct io_uring_buf_ring *br,
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__u16 head, __u16 mask)
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{
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return &br->bufs[head & mask];
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}
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static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len,
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struct io_buffer_list *bl,
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unsigned int issue_flags)
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{
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struct io_uring_buf_ring *br = bl->buf_ring;
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__u16 tail, head = bl->head;
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struct io_uring_buf *buf;
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tail = smp_load_acquire(&br->tail);
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if (unlikely(tail == head))
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return NULL;
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if (head + 1 == tail)
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req->flags |= REQ_F_BL_EMPTY;
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buf = io_ring_head_to_buf(br, head, bl->mask);
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if (*len == 0 || *len > buf->len)
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*len = buf->len;
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req->flags |= REQ_F_BUFFER_RING | REQ_F_BUFFERS_COMMIT;
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req->buf_list = bl;
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req->buf_index = buf->bid;
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if (issue_flags & IO_URING_F_UNLOCKED || !io_file_can_poll(req)) {
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/*
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* If we came in unlocked, we have no choice but to consume the
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* buffer here, otherwise nothing ensures that the buffer won't
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* get used by others. This does mean it'll be pinned until the
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* IO completes, coming in unlocked means we're being called from
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* io-wq context and there may be further retries in async hybrid
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* mode. For the locked case, the caller must call commit when
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* the transfer completes (or if we get -EAGAIN and must poll of
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* retry).
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*/
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req->flags &= ~REQ_F_BUFFERS_COMMIT;
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req->buf_list = NULL;
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bl->head++;
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}
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return u64_to_user_ptr(buf->addr);
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}
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void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
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unsigned int issue_flags)
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct io_buffer_list *bl;
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void __user *ret = NULL;
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io_ring_submit_lock(req->ctx, issue_flags);
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bl = io_buffer_get_list(ctx, req->buf_index);
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if (likely(bl)) {
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if (bl->is_buf_ring)
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ret = io_ring_buffer_select(req, len, bl, issue_flags);
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else
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ret = io_provided_buffer_select(req, len, bl);
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}
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io_ring_submit_unlock(req->ctx, issue_flags);
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return ret;
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}
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/* cap it at a reasonable 256, will be one page even for 4K */
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#define PEEK_MAX_IMPORT 256
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static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg,
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struct io_buffer_list *bl)
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{
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struct io_uring_buf_ring *br = bl->buf_ring;
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struct iovec *iov = arg->iovs;
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int nr_iovs = arg->nr_iovs;
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__u16 nr_avail, tail, head;
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struct io_uring_buf *buf;
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tail = smp_load_acquire(&br->tail);
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head = bl->head;
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nr_avail = min_t(__u16, tail - head, UIO_MAXIOV);
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if (unlikely(!nr_avail))
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return -ENOBUFS;
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buf = io_ring_head_to_buf(br, head, bl->mask);
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if (arg->max_len) {
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int needed;
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needed = (arg->max_len + buf->len - 1) / buf->len;
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needed = min(needed, PEEK_MAX_IMPORT);
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if (nr_avail > needed)
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nr_avail = needed;
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}
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/*
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* only alloc a bigger array if we know we have data to map, eg not
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* a speculative peek operation.
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*/
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if (arg->mode & KBUF_MODE_EXPAND && nr_avail > nr_iovs && arg->max_len) {
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iov = kmalloc_array(nr_avail, sizeof(struct iovec), GFP_KERNEL);
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if (unlikely(!iov))
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return -ENOMEM;
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if (arg->mode & KBUF_MODE_FREE)
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kfree(arg->iovs);
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arg->iovs = iov;
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nr_iovs = nr_avail;
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} else if (nr_avail < nr_iovs) {
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nr_iovs = nr_avail;
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}
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/* set it to max, if not set, so we can use it unconditionally */
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if (!arg->max_len)
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arg->max_len = INT_MAX;
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req->buf_index = buf->bid;
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do {
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/* truncate end piece, if needed */
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if (buf->len > arg->max_len)
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buf->len = arg->max_len;
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iov->iov_base = u64_to_user_ptr(buf->addr);
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iov->iov_len = buf->len;
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iov++;
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arg->out_len += buf->len;
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arg->max_len -= buf->len;
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if (!arg->max_len)
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break;
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buf = io_ring_head_to_buf(br, ++head, bl->mask);
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} while (--nr_iovs);
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if (head == tail)
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req->flags |= REQ_F_BL_EMPTY;
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req->flags |= REQ_F_BUFFER_RING;
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req->buf_list = bl;
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return iov - arg->iovs;
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}
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int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg,
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unsigned int issue_flags)
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct io_buffer_list *bl;
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int ret = -ENOENT;
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io_ring_submit_lock(ctx, issue_flags);
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bl = io_buffer_get_list(ctx, req->buf_index);
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if (unlikely(!bl))
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goto out_unlock;
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if (bl->is_buf_ring) {
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ret = io_ring_buffers_peek(req, arg, bl);
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/*
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* Don't recycle these buffers if we need to go through poll.
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* Nobody else can use them anyway, and holding on to provided
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* buffers for a send/write operation would happen on the app
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* side anyway with normal buffers. Besides, we already
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* committed them, they cannot be put back in the queue.
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*/
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if (ret > 0) {
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req->flags |= REQ_F_BL_NO_RECYCLE;
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req->buf_list->head += ret;
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}
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} else {
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ret = io_provided_buffers_select(req, &arg->out_len, bl, arg->iovs);
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}
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out_unlock:
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io_ring_submit_unlock(ctx, issue_flags);
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return ret;
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}
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int io_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg)
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct io_buffer_list *bl;
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int ret;
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lockdep_assert_held(&ctx->uring_lock);
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bl = io_buffer_get_list(ctx, req->buf_index);
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if (unlikely(!bl))
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return -ENOENT;
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if (bl->is_buf_ring) {
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ret = io_ring_buffers_peek(req, arg, bl);
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if (ret > 0)
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req->flags |= REQ_F_BUFFERS_COMMIT;
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return ret;
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}
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/* don't support multiple buffer selections for legacy */
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return io_provided_buffers_select(req, &arg->max_len, bl, arg->iovs);
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}
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static int __io_remove_buffers(struct io_ring_ctx *ctx,
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struct io_buffer_list *bl, unsigned nbufs)
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{
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unsigned i = 0;
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/* shouldn't happen */
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if (!nbufs)
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return 0;
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if (bl->is_buf_ring) {
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i = bl->buf_ring->tail - bl->head;
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if (bl->buf_nr_pages) {
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int j;
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if (!bl->is_mmap) {
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for (j = 0; j < bl->buf_nr_pages; j++)
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unpin_user_page(bl->buf_pages[j]);
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}
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io_pages_unmap(bl->buf_ring, &bl->buf_pages,
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&bl->buf_nr_pages, bl->is_mmap);
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bl->is_mmap = 0;
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}
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/* make sure it's seen as empty */
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INIT_LIST_HEAD(&bl->buf_list);
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bl->is_buf_ring = 0;
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return i;
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}
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/* protects io_buffers_cache */
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lockdep_assert_held(&ctx->uring_lock);
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while (!list_empty(&bl->buf_list)) {
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struct io_buffer *nxt;
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nxt = list_first_entry(&bl->buf_list, struct io_buffer, list);
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list_move(&nxt->list, &ctx->io_buffers_cache);
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if (++i == nbufs)
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return i;
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cond_resched();
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}
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return i;
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}
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void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
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{
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if (atomic_dec_and_test(&bl->refs)) {
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__io_remove_buffers(ctx, bl, -1U);
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kfree_rcu(bl, rcu);
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}
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}
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void io_destroy_buffers(struct io_ring_ctx *ctx)
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{
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struct io_buffer_list *bl;
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struct list_head *item, *tmp;
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struct io_buffer *buf;
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unsigned long index;
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xa_for_each(&ctx->io_bl_xa, index, bl) {
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xa_erase(&ctx->io_bl_xa, bl->bgid);
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io_put_bl(ctx, bl);
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}
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/*
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* Move deferred locked entries to cache before pruning
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*/
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spin_lock(&ctx->completion_lock);
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if (!list_empty(&ctx->io_buffers_comp))
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list_splice_init(&ctx->io_buffers_comp, &ctx->io_buffers_cache);
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spin_unlock(&ctx->completion_lock);
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list_for_each_safe(item, tmp, &ctx->io_buffers_cache) {
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buf = list_entry(item, struct io_buffer, list);
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kmem_cache_free(io_buf_cachep, buf);
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}
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}
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int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
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u64 tmp;
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if (sqe->rw_flags || sqe->addr || sqe->len || sqe->off ||
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sqe->splice_fd_in)
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return -EINVAL;
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tmp = READ_ONCE(sqe->fd);
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if (!tmp || tmp > MAX_BIDS_PER_BGID)
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return -EINVAL;
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memset(p, 0, sizeof(*p));
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p->nbufs = tmp;
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p->bgid = READ_ONCE(sqe->buf_group);
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return 0;
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}
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int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
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struct io_ring_ctx *ctx = req->ctx;
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struct io_buffer_list *bl;
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int ret = 0;
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io_ring_submit_lock(ctx, issue_flags);
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ret = -ENOENT;
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bl = io_buffer_get_list(ctx, p->bgid);
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if (bl) {
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ret = -EINVAL;
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/* can't use provide/remove buffers command on mapped buffers */
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if (!bl->is_buf_ring)
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ret = __io_remove_buffers(ctx, bl, p->nbufs);
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}
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io_ring_submit_unlock(ctx, issue_flags);
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if (ret < 0)
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req_set_fail(req);
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io_req_set_res(req, ret, 0);
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return IOU_OK;
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}
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int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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unsigned long size, tmp_check;
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struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
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u64 tmp;
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if (sqe->rw_flags || sqe->splice_fd_in)
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return -EINVAL;
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tmp = READ_ONCE(sqe->fd);
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if (!tmp || tmp > MAX_BIDS_PER_BGID)
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return -E2BIG;
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p->nbufs = tmp;
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p->addr = READ_ONCE(sqe->addr);
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p->len = READ_ONCE(sqe->len);
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if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs,
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&size))
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return -EOVERFLOW;
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if (check_add_overflow((unsigned long)p->addr, size, &tmp_check))
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return -EOVERFLOW;
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|
|
size = (unsigned long)p->len * p->nbufs;
|
|
if (!access_ok(u64_to_user_ptr(p->addr), size))
|
|
return -EFAULT;
|
|
|
|
p->bgid = READ_ONCE(sqe->buf_group);
|
|
tmp = READ_ONCE(sqe->off);
|
|
if (tmp > USHRT_MAX)
|
|
return -E2BIG;
|
|
if (tmp + p->nbufs > MAX_BIDS_PER_BGID)
|
|
return -EINVAL;
|
|
p->bid = tmp;
|
|
return 0;
|
|
}
|
|
|
|
#define IO_BUFFER_ALLOC_BATCH 64
|
|
|
|
static int io_refill_buffer_cache(struct io_ring_ctx *ctx)
|
|
{
|
|
struct io_buffer *bufs[IO_BUFFER_ALLOC_BATCH];
|
|
int allocated;
|
|
|
|
/*
|
|
* 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
|
|
* batch of buffer entries and add those to our freelist.
|
|
*/
|
|
|
|
allocated = kmem_cache_alloc_bulk(io_buf_cachep, GFP_KERNEL_ACCOUNT,
|
|
ARRAY_SIZE(bufs), (void **) bufs);
|
|
if (unlikely(!allocated)) {
|
|
/*
|
|
* Bulk alloc is all-or-nothing. If we fail to get a batch,
|
|
* retry single alloc to be on the safe side.
|
|
*/
|
|
bufs[0] = kmem_cache_alloc(io_buf_cachep, GFP_KERNEL);
|
|
if (!bufs[0])
|
|
return -ENOMEM;
|
|
allocated = 1;
|
|
}
|
|
|
|
while (allocated)
|
|
list_add_tail(&bufs[--allocated]->list, &ctx->io_buffers_cache);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf,
|
|
struct io_buffer_list *bl)
|
|
{
|
|
struct io_buffer *buf;
|
|
u64 addr = pbuf->addr;
|
|
int i, bid = pbuf->bid;
|
|
|
|
for (i = 0; i < pbuf->nbufs; i++) {
|
|
if (list_empty(&ctx->io_buffers_cache) &&
|
|
io_refill_buffer_cache(ctx))
|
|
break;
|
|
buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer,
|
|
list);
|
|
list_move_tail(&buf->list, &bl->buf_list);
|
|
buf->addr = addr;
|
|
buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT);
|
|
buf->bid = bid;
|
|
buf->bgid = pbuf->bgid;
|
|
addr += pbuf->len;
|
|
bid++;
|
|
cond_resched();
|
|
}
|
|
|
|
return i ? 0 : -ENOMEM;
|
|
}
|
|
|
|
int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
|
|
{
|
|
struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
|
|
struct io_ring_ctx *ctx = req->ctx;
|
|
struct io_buffer_list *bl;
|
|
int ret = 0;
|
|
|
|
io_ring_submit_lock(ctx, issue_flags);
|
|
|
|
bl = io_buffer_get_list(ctx, p->bgid);
|
|
if (unlikely(!bl)) {
|
|
bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT);
|
|
if (!bl) {
|
|
ret = -ENOMEM;
|
|
goto err;
|
|
}
|
|
INIT_LIST_HEAD(&bl->buf_list);
|
|
ret = io_buffer_add_list(ctx, bl, p->bgid);
|
|
if (ret) {
|
|
/*
|
|
* Doesn't need rcu free as it was never visible, but
|
|
* let's keep it consistent throughout.
|
|
*/
|
|
kfree_rcu(bl, rcu);
|
|
goto err;
|
|
}
|
|
}
|
|
/* can't add buffers via this command for a mapped buffer ring */
|
|
if (bl->is_buf_ring) {
|
|
ret = -EINVAL;
|
|
goto err;
|
|
}
|
|
|
|
ret = io_add_buffers(ctx, p, bl);
|
|
err:
|
|
io_ring_submit_unlock(ctx, issue_flags);
|
|
|
|
if (ret < 0)
|
|
req_set_fail(req);
|
|
io_req_set_res(req, ret, 0);
|
|
return IOU_OK;
|
|
}
|
|
|
|
static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,
|
|
struct io_buffer_list *bl)
|
|
{
|
|
struct io_uring_buf_ring *br = NULL;
|
|
struct page **pages;
|
|
int nr_pages, ret;
|
|
|
|
pages = io_pin_pages(reg->ring_addr,
|
|
flex_array_size(br, bufs, reg->ring_entries),
|
|
&nr_pages);
|
|
if (IS_ERR(pages))
|
|
return PTR_ERR(pages);
|
|
|
|
br = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
|
|
if (!br) {
|
|
ret = -ENOMEM;
|
|
goto error_unpin;
|
|
}
|
|
|
|
#ifdef SHM_COLOUR
|
|
/*
|
|
* On platforms that have specific aliasing requirements, SHM_COLOUR
|
|
* is set and we must guarantee that the kernel and user side align
|
|
* nicely. We cannot do that if IOU_PBUF_RING_MMAP isn't set and
|
|
* the application mmap's the provided ring buffer. Fail the request
|
|
* if we, by chance, don't end up with aligned addresses. The app
|
|
* should use IOU_PBUF_RING_MMAP instead, and liburing will handle
|
|
* this transparently.
|
|
*/
|
|
if ((reg->ring_addr | (unsigned long) br) & (SHM_COLOUR - 1)) {
|
|
ret = -EINVAL;
|
|
goto error_unpin;
|
|
}
|
|
#endif
|
|
bl->buf_pages = pages;
|
|
bl->buf_nr_pages = nr_pages;
|
|
bl->buf_ring = br;
|
|
bl->is_buf_ring = 1;
|
|
bl->is_mmap = 0;
|
|
return 0;
|
|
error_unpin:
|
|
unpin_user_pages(pages, nr_pages);
|
|
kvfree(pages);
|
|
vunmap(br);
|
|
return ret;
|
|
}
|
|
|
|
static int io_alloc_pbuf_ring(struct io_ring_ctx *ctx,
|
|
struct io_uring_buf_reg *reg,
|
|
struct io_buffer_list *bl)
|
|
{
|
|
size_t ring_size;
|
|
|
|
ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring);
|
|
|
|
bl->buf_ring = io_pages_map(&bl->buf_pages, &bl->buf_nr_pages, ring_size);
|
|
if (!bl->buf_ring)
|
|
return -ENOMEM;
|
|
|
|
bl->is_buf_ring = 1;
|
|
bl->is_mmap = 1;
|
|
return 0;
|
|
}
|
|
|
|
int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
|
|
{
|
|
struct io_uring_buf_reg reg;
|
|
struct io_buffer_list *bl, *free_bl = NULL;
|
|
int ret;
|
|
|
|
lockdep_assert_held(&ctx->uring_lock);
|
|
|
|
if (copy_from_user(®, arg, sizeof(reg)))
|
|
return -EFAULT;
|
|
|
|
if (reg.resv[0] || reg.resv[1] || reg.resv[2])
|
|
return -EINVAL;
|
|
if (reg.flags & ~IOU_PBUF_RING_MMAP)
|
|
return -EINVAL;
|
|
if (!(reg.flags & IOU_PBUF_RING_MMAP)) {
|
|
if (!reg.ring_addr)
|
|
return -EFAULT;
|
|
if (reg.ring_addr & ~PAGE_MASK)
|
|
return -EINVAL;
|
|
} else {
|
|
if (reg.ring_addr)
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!is_power_of_2(reg.ring_entries))
|
|
return -EINVAL;
|
|
|
|
/* cannot disambiguate full vs empty due to head/tail size */
|
|
if (reg.ring_entries >= 65536)
|
|
return -EINVAL;
|
|
|
|
bl = io_buffer_get_list(ctx, reg.bgid);
|
|
if (bl) {
|
|
/* if mapped buffer ring OR classic exists, don't allow */
|
|
if (bl->is_buf_ring || !list_empty(&bl->buf_list))
|
|
return -EEXIST;
|
|
} else {
|
|
free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
|
|
if (!bl)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (!(reg.flags & IOU_PBUF_RING_MMAP))
|
|
ret = io_pin_pbuf_ring(®, bl);
|
|
else
|
|
ret = io_alloc_pbuf_ring(ctx, ®, bl);
|
|
|
|
if (!ret) {
|
|
bl->nr_entries = reg.ring_entries;
|
|
bl->mask = reg.ring_entries - 1;
|
|
|
|
io_buffer_add_list(ctx, bl, reg.bgid);
|
|
return 0;
|
|
}
|
|
|
|
kfree_rcu(free_bl, rcu);
|
|
return ret;
|
|
}
|
|
|
|
int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
|
|
{
|
|
struct io_uring_buf_reg reg;
|
|
struct io_buffer_list *bl;
|
|
|
|
lockdep_assert_held(&ctx->uring_lock);
|
|
|
|
if (copy_from_user(®, arg, sizeof(reg)))
|
|
return -EFAULT;
|
|
if (reg.resv[0] || reg.resv[1] || reg.resv[2])
|
|
return -EINVAL;
|
|
if (reg.flags)
|
|
return -EINVAL;
|
|
|
|
bl = io_buffer_get_list(ctx, reg.bgid);
|
|
if (!bl)
|
|
return -ENOENT;
|
|
if (!bl->is_buf_ring)
|
|
return -EINVAL;
|
|
|
|
xa_erase(&ctx->io_bl_xa, bl->bgid);
|
|
io_put_bl(ctx, bl);
|
|
return 0;
|
|
}
|
|
|
|
int io_register_pbuf_status(struct io_ring_ctx *ctx, void __user *arg)
|
|
{
|
|
struct io_uring_buf_status buf_status;
|
|
struct io_buffer_list *bl;
|
|
int i;
|
|
|
|
if (copy_from_user(&buf_status, arg, sizeof(buf_status)))
|
|
return -EFAULT;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(buf_status.resv); i++)
|
|
if (buf_status.resv[i])
|
|
return -EINVAL;
|
|
|
|
bl = io_buffer_get_list(ctx, buf_status.buf_group);
|
|
if (!bl)
|
|
return -ENOENT;
|
|
if (!bl->is_buf_ring)
|
|
return -EINVAL;
|
|
|
|
buf_status.head = bl->head;
|
|
if (copy_to_user(arg, &buf_status, sizeof(buf_status)))
|
|
return -EFAULT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx,
|
|
unsigned long bgid)
|
|
{
|
|
struct io_buffer_list *bl;
|
|
bool ret;
|
|
|
|
/*
|
|
* We have to be a bit careful here - we're inside mmap and cannot grab
|
|
* the uring_lock. This means the buffer_list could be simultaneously
|
|
* going away, if someone is trying to be sneaky. Look it up under rcu
|
|
* so we know it's not going away, and attempt to grab a reference to
|
|
* it. If the ref is already zero, then fail the mapping. If successful,
|
|
* the caller will call io_put_bl() to drop the the reference at at the
|
|
* end. This may then safely free the buffer_list (and drop the pages)
|
|
* at that point, vm_insert_pages() would've already grabbed the
|
|
* necessary vma references.
|
|
*/
|
|
rcu_read_lock();
|
|
bl = xa_load(&ctx->io_bl_xa, bgid);
|
|
/* must be a mmap'able buffer ring and have pages */
|
|
ret = false;
|
|
if (bl && bl->is_mmap)
|
|
ret = atomic_inc_not_zero(&bl->refs);
|
|
rcu_read_unlock();
|
|
|
|
if (ret)
|
|
return bl;
|
|
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
int io_pbuf_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
struct io_ring_ctx *ctx = file->private_data;
|
|
loff_t pgoff = vma->vm_pgoff << PAGE_SHIFT;
|
|
struct io_buffer_list *bl;
|
|
int bgid, ret;
|
|
|
|
bgid = (pgoff & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;
|
|
bl = io_pbuf_get_bl(ctx, bgid);
|
|
if (IS_ERR(bl))
|
|
return PTR_ERR(bl);
|
|
|
|
ret = io_uring_mmap_pages(ctx, vma, bl->buf_pages, bl->buf_nr_pages);
|
|
io_put_bl(ctx, bl);
|
|
return ret;
|
|
}
|