394 lines
9.1 KiB
C
394 lines
9.1 KiB
C
/*
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* Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <unistd.h>
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#include <sched.h>
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#include <signal.h>
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#include <errno.h>
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#include <sys/time.h>
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#include <asm/unistd.h>
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#include "aio.h"
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#include "init.h"
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#include "kern_constants.h"
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#include "kern_util.h"
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#include "os.h"
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#include "user.h"
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struct aio_thread_req {
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enum aio_type type;
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int io_fd;
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unsigned long long offset;
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char *buf;
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int len;
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struct aio_context *aio;
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};
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#if defined(HAVE_AIO_ABI)
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#include <linux/aio_abi.h>
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/*
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* If we have the headers, we are going to build with AIO enabled.
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* If we don't have aio in libc, we define the necessary stubs here.
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*/
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#if !defined(HAVE_AIO_LIBC)
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static long io_setup(int n, aio_context_t *ctxp)
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{
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return syscall(__NR_io_setup, n, ctxp);
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}
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static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
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{
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return syscall(__NR_io_submit, ctx, nr, iocbpp);
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}
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static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
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struct io_event *events, struct timespec *timeout)
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{
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return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
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}
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#endif
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/*
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* The AIO_MMAP cases force the mmapped page into memory here
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* rather than in whatever place first touches the data. I used
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* to do this by touching the page, but that's delicate because
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* gcc is prone to optimizing that away. So, what's done here
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* is we read from the descriptor from which the page was
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* mapped. The caller is required to pass an offset which is
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* inside the page that was mapped. Thus, when the read
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* returns, we know that the page is in the page cache, and
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* that it now backs the mmapped area.
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*/
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static int do_aio(aio_context_t ctx, enum aio_type type, int fd, char *buf,
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int len, unsigned long long offset, struct aio_context *aio)
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{
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struct iocb *iocbp = & ((struct iocb) {
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.aio_data = (unsigned long) aio,
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.aio_fildes = fd,
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.aio_buf = (unsigned long) buf,
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.aio_nbytes = len,
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.aio_offset = offset
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});
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char c;
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switch (type) {
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case AIO_READ:
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iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
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break;
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case AIO_WRITE:
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iocbp->aio_lio_opcode = IOCB_CMD_PWRITE;
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break;
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case AIO_MMAP:
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iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
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iocbp->aio_buf = (unsigned long) &c;
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iocbp->aio_nbytes = sizeof(c);
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break;
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default:
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printk(UM_KERN_ERR "Bogus op in do_aio - %d\n", type);
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return -EINVAL;
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}
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return (io_submit(ctx, 1, &iocbp) > 0) ? 0 : -errno;
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}
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/* Initialized in an initcall and unchanged thereafter */
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static aio_context_t ctx = 0;
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static int aio_thread(void *arg)
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{
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struct aio_thread_reply reply;
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struct io_event event;
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int err, n, reply_fd;
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signal(SIGWINCH, SIG_IGN);
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while (1) {
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n = io_getevents(ctx, 1, 1, &event, NULL);
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if (n < 0) {
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if (errno == EINTR)
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continue;
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printk(UM_KERN_ERR "aio_thread - io_getevents failed, "
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"errno = %d\n", errno);
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}
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else {
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reply = ((struct aio_thread_reply)
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{ .data = (void *) (long) event.data,
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.err = event.res });
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reply_fd = ((struct aio_context *) reply.data)->reply_fd;
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err = write(reply_fd, &reply, sizeof(reply));
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if (err != sizeof(reply))
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printk(UM_KERN_ERR "aio_thread - write failed, "
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"fd = %d, err = %d\n", reply_fd, errno);
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}
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}
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return 0;
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}
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#endif
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static int do_not_aio(struct aio_thread_req *req)
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{
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char c;
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unsigned long long actual;
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int n;
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actual = lseek64(req->io_fd, req->offset, SEEK_SET);
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if (actual != req->offset)
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return -errno;
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switch (req->type) {
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case AIO_READ:
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n = read(req->io_fd, req->buf, req->len);
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break;
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case AIO_WRITE:
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n = write(req->io_fd, req->buf, req->len);
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break;
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case AIO_MMAP:
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n = read(req->io_fd, &c, sizeof(c));
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break;
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default:
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printk(UM_KERN_ERR "do_not_aio - bad request type : %d\n",
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req->type);
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return -EINVAL;
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}
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if (n < 0)
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return -errno;
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return 0;
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}
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/* These are initialized in initcalls and not changed */
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static int aio_req_fd_r = -1;
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static int aio_req_fd_w = -1;
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static int aio_pid = -1;
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static unsigned long aio_stack;
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static int not_aio_thread(void *arg)
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{
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struct aio_thread_req req;
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struct aio_thread_reply reply;
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int err;
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signal(SIGWINCH, SIG_IGN);
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while (1) {
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err = read(aio_req_fd_r, &req, sizeof(req));
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if (err != sizeof(req)) {
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if (err < 0)
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printk(UM_KERN_ERR "not_aio_thread - "
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"read failed, fd = %d, err = %d\n",
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aio_req_fd_r,
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errno);
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else {
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printk(UM_KERN_ERR "not_aio_thread - short "
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"read, fd = %d, length = %d\n",
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aio_req_fd_r, err);
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}
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continue;
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}
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err = do_not_aio(&req);
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reply = ((struct aio_thread_reply) { .data = req.aio,
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.err = err });
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err = write(req.aio->reply_fd, &reply, sizeof(reply));
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if (err != sizeof(reply))
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printk(UM_KERN_ERR "not_aio_thread - write failed, "
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"fd = %d, err = %d\n", req.aio->reply_fd, errno);
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}
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return 0;
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}
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static int init_aio_24(void)
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{
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int fds[2], err;
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err = os_pipe(fds, 1, 1);
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if (err)
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goto out;
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aio_req_fd_w = fds[0];
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aio_req_fd_r = fds[1];
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err = os_set_fd_block(aio_req_fd_w, 0);
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if (err)
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goto out_close_pipe;
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err = run_helper_thread(not_aio_thread, NULL,
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CLONE_FILES | CLONE_VM, &aio_stack);
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if (err < 0)
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goto out_close_pipe;
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aio_pid = err;
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goto out;
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out_close_pipe:
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close(fds[0]);
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close(fds[1]);
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aio_req_fd_w = -1;
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aio_req_fd_r = -1;
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out:
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#ifndef HAVE_AIO_ABI
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printk(UM_KERN_INFO "/usr/include/linux/aio_abi.h not present during "
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"build\n");
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#endif
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printk(UM_KERN_INFO "2.6 host AIO support not used - falling back to "
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"I/O thread\n");
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return 0;
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}
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#ifdef HAVE_AIO_ABI
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#define DEFAULT_24_AIO 0
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static int init_aio_26(void)
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{
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int err;
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if (io_setup(256, &ctx)) {
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err = -errno;
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printk(UM_KERN_ERR "aio_thread failed to initialize context, "
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"err = %d\n", errno);
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return err;
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}
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err = run_helper_thread(aio_thread, NULL,
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CLONE_FILES | CLONE_VM, &aio_stack);
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if (err < 0)
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return err;
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aio_pid = err;
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printk(UM_KERN_INFO "Using 2.6 host AIO\n");
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return 0;
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}
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static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
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unsigned long long offset, struct aio_context *aio)
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{
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struct aio_thread_reply reply;
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int err;
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err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
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if (err) {
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reply = ((struct aio_thread_reply) { .data = aio,
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.err = err });
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err = write(aio->reply_fd, &reply, sizeof(reply));
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if (err != sizeof(reply)) {
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err = -errno;
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printk(UM_KERN_ERR "submit_aio_26 - write failed, "
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"fd = %d, err = %d\n", aio->reply_fd, -err);
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}
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else err = 0;
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}
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return err;
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}
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#else
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#define DEFAULT_24_AIO 1
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static int init_aio_26(void)
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{
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return -ENOSYS;
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}
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static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
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unsigned long long offset, struct aio_context *aio)
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{
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return -ENOSYS;
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}
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#endif
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/* Initialized in an initcall and unchanged thereafter */
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static int aio_24 = DEFAULT_24_AIO;
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static int __init set_aio_24(char *name, int *add)
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{
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aio_24 = 1;
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return 0;
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}
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__uml_setup("aio=2.4", set_aio_24,
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"aio=2.4\n"
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" This is used to force UML to use 2.4-style AIO even when 2.6 AIO is\n"
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" available. 2.4 AIO is a single thread that handles one request at a\n"
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" time, synchronously. 2.6 AIO is a thread which uses the 2.6 AIO \n"
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" interface to handle an arbitrary number of pending requests. 2.6 AIO \n"
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" is not available in tt mode, on 2.4 hosts, or when UML is built with\n"
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" /usr/include/linux/aio_abi.h not available. Many distributions don't\n"
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" include aio_abi.h, so you will need to copy it from a kernel tree to\n"
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" your /usr/include/linux in order to build an AIO-capable UML\n\n"
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);
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static int init_aio(void)
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{
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int err;
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if (!aio_24) {
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err = init_aio_26();
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if (err && (errno == ENOSYS)) {
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printk(UM_KERN_INFO "2.6 AIO not supported on the "
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"host - reverting to 2.4 AIO\n");
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aio_24 = 1;
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}
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else return err;
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}
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if (aio_24)
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return init_aio_24();
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return 0;
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}
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/*
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* The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
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* needs to be called when the kernel is running because it calls run_helper,
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* which needs get_free_page. exit_aio is a __uml_exitcall because the generic
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* kernel does not run __exitcalls on shutdown, and can't because many of them
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* break when called outside of module unloading.
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*/
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__initcall(init_aio);
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static void exit_aio(void)
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{
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if (aio_pid != -1) {
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os_kill_process(aio_pid, 1);
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free_stack(aio_stack, 0);
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}
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}
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__uml_exitcall(exit_aio);
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static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
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unsigned long long offset, struct aio_context *aio)
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{
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struct aio_thread_req req = { .type = type,
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.io_fd = io_fd,
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.offset = offset,
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.buf = buf,
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.len = len,
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.aio = aio,
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};
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int err;
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err = write(aio_req_fd_w, &req, sizeof(req));
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if (err == sizeof(req))
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err = 0;
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else err = -errno;
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return err;
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}
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int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
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unsigned long long offset, int reply_fd,
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struct aio_context *aio)
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{
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aio->reply_fd = reply_fd;
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if (aio_24)
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return submit_aio_24(type, io_fd, buf, len, offset, aio);
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else
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return submit_aio_26(type, io_fd, buf, len, offset, aio);
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}
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