550 lines
13 KiB
C
550 lines
13 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/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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#define IO_BUFFER_LIST_BUF_PER_PAGE (PAGE_SIZE / sizeof(struct io_uring_buf))
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#define BGID_ARRAY 64
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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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__u16 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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if (ctx->io_bl && bgid < BGID_ARRAY)
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return &ctx->io_bl[bgid];
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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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bl->bgid = bgid;
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if (bgid < BGID_ARRAY)
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return 0;
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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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void 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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/*
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* For legacy provided buffer mode, don't recycle if we already did
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* IO to this buffer. For ring-mapped provided buffer mode, we should
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* increment ring->head to explicitly monopolize the buffer to avoid
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* multiple use.
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*/
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if (req->flags & REQ_F_PARTIAL_IO)
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return;
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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;
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}
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unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags)
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{
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unsigned int cflags;
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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 (req->flags & REQ_F_BUFFER_RING) {
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/* no buffers to recycle for this case */
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cflags = __io_put_kbuf_list(req, NULL);
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} else 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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cflags = __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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cflags = __io_put_kbuf_list(req, &req->ctx->io_buffers_cache);
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}
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return cflags;
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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 > kbuf->len)
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*len = kbuf->len;
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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 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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struct io_uring_buf *buf;
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__u16 head = bl->head;
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if (unlikely(smp_load_acquire(&br->tail) == head))
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return NULL;
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head &= bl->mask;
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if (head < IO_BUFFER_LIST_BUF_PER_PAGE) {
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buf = &br->bufs[head];
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} else {
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int off = head & (IO_BUFFER_LIST_BUF_PER_PAGE - 1);
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int index = head / IO_BUFFER_LIST_BUF_PER_PAGE;
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buf = page_address(bl->buf_pages[index]);
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buf += off;
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}
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if (*len > buf->len)
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*len = buf->len;
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req->flags |= REQ_F_BUFFER_RING;
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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 || !file_can_poll(req->file)) {
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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->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->buf_nr_pages)
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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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static __cold int io_init_bl_list(struct io_ring_ctx *ctx)
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{
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int i;
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ctx->io_bl = kcalloc(BGID_ARRAY, sizeof(struct io_buffer_list),
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GFP_KERNEL);
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if (!ctx->io_bl)
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return -ENOMEM;
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for (i = 0; i < BGID_ARRAY; i++) {
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INIT_LIST_HEAD(&ctx->io_bl[i].buf_list);
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ctx->io_bl[i].bgid = i;
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}
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return 0;
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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->buf_nr_pages) {
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int j;
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i = bl->buf_ring->tail - bl->head;
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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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kvfree(bl->buf_pages);
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bl->buf_pages = NULL;
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bl->buf_nr_pages = 0;
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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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return i;
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}
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/* the head kbuf is the list itself */
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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_del(&nxt->list);
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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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i++;
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return i;
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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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unsigned long index;
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int i;
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for (i = 0; i < BGID_ARRAY; i++) {
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if (!ctx->io_bl)
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break;
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__io_remove_buffers(ctx, &ctx->io_bl[i], -1U);
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}
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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_remove_buffers(ctx, bl, -1U);
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kfree(bl);
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}
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while (!list_empty(&ctx->io_buffers_pages)) {
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struct page *page;
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page = list_first_entry(&ctx->io_buffers_pages, struct page, lru);
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list_del_init(&page->lru);
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__free_page(page);
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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);
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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 > USHRT_MAX)
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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);
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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->buf_nr_pages)
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ret = __io_remove_buffers(ctx, bl, p->nbufs);
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}
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if (ret < 0)
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req_set_fail(req);
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/* complete before unlock, IOPOLL may need the lock */
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io_req_set_res(req, ret, 0);
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__io_req_complete(req, issue_flags);
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io_ring_submit_unlock(ctx, issue_flags);
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return IOU_ISSUE_SKIP_COMPLETE;
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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);
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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 > USHRT_MAX)
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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;
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if (!access_ok(u64_to_user_ptr(p->addr), size))
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return -EFAULT;
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p->bgid = READ_ONCE(sqe->buf_group);
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tmp = READ_ONCE(sqe->off);
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if (tmp > USHRT_MAX)
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return -E2BIG;
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p->bid = tmp;
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return 0;
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}
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static int io_refill_buffer_cache(struct io_ring_ctx *ctx)
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{
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struct io_buffer *buf;
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struct page *page;
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int bufs_in_page;
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/*
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* Completions that don't happen inline (eg not under uring_lock) will
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* add to ->io_buffers_comp. If we don't have any free buffers, check
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* the completion list and splice those entries first.
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*/
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if (!list_empty_careful(&ctx->io_buffers_comp)) {
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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,
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&ctx->io_buffers_cache);
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spin_unlock(&ctx->completion_lock);
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return 0;
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}
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spin_unlock(&ctx->completion_lock);
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}
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/*
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* No free buffers and no completion entries either. Allocate a new
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* page worth of buffer entries and add those to our freelist.
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*/
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page = alloc_page(GFP_KERNEL_ACCOUNT);
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if (!page)
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return -ENOMEM;
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list_add(&page->lru, &ctx->io_buffers_pages);
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buf = page_address(page);
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bufs_in_page = PAGE_SIZE / sizeof(*buf);
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while (bufs_in_page) {
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list_add_tail(&buf->list, &ctx->io_buffers_cache);
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buf++;
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bufs_in_page--;
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}
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return 0;
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}
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static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf,
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struct io_buffer_list *bl)
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{
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struct io_buffer *buf;
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u64 addr = pbuf->addr;
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int i, bid = pbuf->bid;
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for (i = 0; i < pbuf->nbufs; i++) {
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if (list_empty(&ctx->io_buffers_cache) &&
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io_refill_buffer_cache(ctx))
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break;
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buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer,
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list);
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list_move_tail(&buf->list, &bl->buf_list);
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buf->addr = addr;
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buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT);
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buf->bid = bid;
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buf->bgid = pbuf->bgid;
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addr += pbuf->len;
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bid++;
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cond_resched();
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}
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return i ? 0 : -ENOMEM;
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}
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int io_provide_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);
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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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if (unlikely(p->bgid < BGID_ARRAY && !ctx->io_bl)) {
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ret = io_init_bl_list(ctx);
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if (ret)
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goto err;
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}
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bl = io_buffer_get_list(ctx, p->bgid);
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if (unlikely(!bl)) {
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bl = kzalloc(sizeof(*bl), GFP_KERNEL);
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if (!bl) {
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ret = -ENOMEM;
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goto err;
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}
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INIT_LIST_HEAD(&bl->buf_list);
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ret = io_buffer_add_list(ctx, bl, p->bgid);
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if (ret) {
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kfree(bl);
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goto err;
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}
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}
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/* can't add buffers via this command for a mapped buffer ring */
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if (bl->buf_nr_pages) {
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ret = -EINVAL;
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goto err;
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}
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ret = io_add_buffers(ctx, p, bl);
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err:
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if (ret < 0)
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req_set_fail(req);
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/* complete before unlock, IOPOLL may need the lock */
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io_req_set_res(req, ret, 0);
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__io_req_complete(req, issue_flags);
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io_ring_submit_unlock(ctx, issue_flags);
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return IOU_ISSUE_SKIP_COMPLETE;
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}
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int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
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{
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struct io_uring_buf_ring *br;
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struct io_uring_buf_reg reg;
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struct io_buffer_list *bl, *free_bl = NULL;
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struct page **pages;
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int nr_pages;
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if (copy_from_user(®, arg, sizeof(reg)))
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return -EFAULT;
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if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2])
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return -EINVAL;
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if (!reg.ring_addr)
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return -EFAULT;
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if (reg.ring_addr & ~PAGE_MASK)
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return -EINVAL;
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if (!is_power_of_2(reg.ring_entries))
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return -EINVAL;
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/* cannot disambiguate full vs empty due to head/tail size */
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if (reg.ring_entries >= 65536)
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return -EINVAL;
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if (unlikely(reg.bgid < BGID_ARRAY && !ctx->io_bl)) {
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int ret = io_init_bl_list(ctx);
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if (ret)
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return ret;
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}
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bl = io_buffer_get_list(ctx, reg.bgid);
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if (bl) {
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/* if mapped buffer ring OR classic exists, don't allow */
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if (bl->buf_nr_pages || !list_empty(&bl->buf_list))
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return -EEXIST;
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} else {
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free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
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if (!bl)
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return -ENOMEM;
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}
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pages = io_pin_pages(reg.ring_addr,
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struct_size(br, bufs, reg.ring_entries),
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&nr_pages);
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|
if (IS_ERR(pages)) {
|
|
kfree(free_bl);
|
|
return PTR_ERR(pages);
|
|
}
|
|
|
|
br = page_address(pages[0]);
|
|
bl->buf_pages = pages;
|
|
bl->buf_nr_pages = nr_pages;
|
|
bl->nr_entries = reg.ring_entries;
|
|
bl->buf_ring = br;
|
|
bl->mask = reg.ring_entries - 1;
|
|
io_buffer_add_list(ctx, bl, reg.bgid);
|
|
return 0;
|
|
}
|
|
|
|
int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
|
|
{
|
|
struct io_uring_buf_reg reg;
|
|
struct io_buffer_list *bl;
|
|
|
|
if (copy_from_user(®, arg, sizeof(reg)))
|
|
return -EFAULT;
|
|
if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2])
|
|
return -EINVAL;
|
|
|
|
bl = io_buffer_get_list(ctx, reg.bgid);
|
|
if (!bl)
|
|
return -ENOENT;
|
|
if (!bl->buf_nr_pages)
|
|
return -EINVAL;
|
|
|
|
__io_remove_buffers(ctx, bl, -1U);
|
|
if (bl->bgid >= BGID_ARRAY) {
|
|
xa_erase(&ctx->io_bl_xa, bl->bgid);
|
|
kfree(bl);
|
|
}
|
|
return 0;
|
|
}
|