Quelle splice.c Sprache: C

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/io_uring.h>
#include <linux/splice.h>

#include <uapi/linux/io_uring.h>

#include "io_uring.h"
#include "splice.h"

struct io_splice {
struct file   *file_out;
loff_t    off_out;
loff_t    off_in;
u64    len;
int    splice_fd_in;
unsigned int   flags;
struct io_rsrc_node  *rsrc_node;
};

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

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);
sp->rsrc_node = NULL;
req->flags |= REQ_F_FORCE_ASYNC;
return 0;
}

int io_tee_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
if (READ_ONCE(sqe->splice_off_in) || READ_ONCE(sqe->off))
  return -EINVAL;
return __io_splice_prep(req, sqe);
}

void io_splice_cleanup(struct io_kiocb *req)
{
struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);

if (sp->rsrc_node)
  io_put_rsrc_node(req->ctx, sp->rsrc_node);
}

static struct file *io_splice_get_file(struct io_kiocb *req,
           unsigned int issue_flags)
{
struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);
struct io_ring_ctx *ctx = req->ctx;
struct io_rsrc_node *node;
struct file *file = NULL;

if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
  return io_file_get_normal(req, sp->splice_fd_in);

io_ring_submit_lock(ctx, issue_flags);
node = io_rsrc_node_lookup(&ctx->file_table.data, sp->splice_fd_in);
if (node) {
  node->refs++;
  sp->rsrc_node = node;
  file = io_slot_file(node);
  req->flags |= REQ_F_NEED_CLEANUP;
}
io_ring_submit_unlock(ctx, issue_flags);
return file;
}

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

WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK);

in = io_splice_get_file(req, issue_flags);
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))
  fput(in);
done:
if (ret != sp->len)
  req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_COMPLETE;
}

int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);

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

int io_splice(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice);
struct file *out = sp->file_out;
unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
loff_t *poff_in, *poff_out;
struct file *in;
ssize_t ret = 0;

WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK);

in = io_splice_get_file(req, issue_flags);
if (!in) {
  ret = -EBADF;
  goto done;
}

poff_in = (sp->off_in == -1) ? NULL : &sp->off_in;
poff_out = (sp->off_out == -1) ? NULL : &sp->off_out;

if (sp->len)
  ret = do_splice(in, poff_in, out, poff_out, sp->len, flags);

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

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