aboutsummaryrefslogtreecommitdiffstats
path: root/arch/um/os-Linux/aio.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/um/os-Linux/aio.c')
-rw-r--r--arch/um/os-Linux/aio.c414
1 files changed, 414 insertions, 0 deletions
diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
new file mode 100644
index 000000000000..b04897cd995d
--- /dev/null
+++ b/arch/um/os-Linux/aio.c
@@ -0,0 +1,414 @@
+/*
+ * Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+#include <errno.h>
+#include <sched.h>
+#include <sys/syscall.h>
+#include "os.h"
+#include "helper.h"
+#include "aio.h"
+#include "init.h"
+#include "user.h"
+#include "mode.h"
+
+static int aio_req_fd_r = -1;
+static int aio_req_fd_w = -1;
+
+static int update_aio(struct aio_context *aio, int res)
+{
+ if(res < 0)
+ aio->len = res;
+ else if((res == 0) && (aio->type == AIO_READ)){
+ /* This is the EOF case - we have hit the end of the file
+ * and it ends in a partial block, so we fill the end of
+ * the block with zeros and claim success.
+ */
+ memset(aio->data, 0, aio->len);
+ aio->len = 0;
+ }
+ else if(res > 0){
+ aio->len -= res;
+ aio->data += res;
+ aio->offset += res;
+ return aio->len;
+ }
+
+ return 0;
+}
+
+#if defined(HAVE_AIO_ABI)
+#include <linux/aio_abi.h>
+
+/* If we have the headers, we are going to build with AIO enabled.
+ * If we don't have aio in libc, we define the necessary stubs here.
+ */
+
+#if !defined(HAVE_AIO_LIBC)
+
+static long io_setup(int n, aio_context_t *ctxp)
+{
+ return syscall(__NR_io_setup, n, ctxp);
+}
+
+static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
+{
+ return syscall(__NR_io_submit, ctx, nr, iocbpp);
+}
+
+static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
+ struct io_event *events, struct timespec *timeout)
+{
+ return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
+}
+
+#endif
+
+/* The AIO_MMAP cases force the mmapped page into memory here
+ * rather than in whatever place first touches the data. I used
+ * to do this by touching the page, but that's delicate because
+ * gcc is prone to optimizing that away. So, what's done here
+ * is we read from the descriptor from which the page was
+ * mapped. The caller is required to pass an offset which is
+ * inside the page that was mapped. Thus, when the read
+ * returns, we know that the page is in the page cache, and
+ * that it now backs the mmapped area.
+ */
+
+static int do_aio(aio_context_t ctx, struct aio_context *aio)
+{
+ struct iocb iocb, *iocbp = &iocb;
+ char c;
+ int err;
+
+ iocb = ((struct iocb) { .aio_data = (unsigned long) aio,
+ .aio_reqprio = 0,
+ .aio_fildes = aio->fd,
+ .aio_buf = (unsigned long) aio->data,
+ .aio_nbytes = aio->len,
+ .aio_offset = aio->offset,
+ .aio_reserved1 = 0,
+ .aio_reserved2 = 0,
+ .aio_reserved3 = 0 });
+
+ switch(aio->type){
+ case AIO_READ:
+ iocb.aio_lio_opcode = IOCB_CMD_PREAD;
+ break;
+ case AIO_WRITE:
+ iocb.aio_lio_opcode = IOCB_CMD_PWRITE;
+ break;
+ case AIO_MMAP:
+ iocb.aio_lio_opcode = IOCB_CMD_PREAD;
+ iocb.aio_buf = (unsigned long) &c;
+ iocb.aio_nbytes = sizeof(c);
+ break;
+ default:
+ printk("Bogus op in do_aio - %d\n", aio->type);
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = io_submit(ctx, 1, &iocbp);
+ if(err > 0)
+ err = 0;
+
+ out:
+ return err;
+}
+
+static aio_context_t ctx = 0;
+
+static int aio_thread(void *arg)
+{
+ struct aio_thread_reply reply;
+ struct aio_context *aio;
+ struct io_event event;
+ int err, n;
+
+ signal(SIGWINCH, SIG_IGN);
+
+ while(1){
+ n = io_getevents(ctx, 1, 1, &event, NULL);
+ if(n < 0){
+ if(errno == EINTR)
+ continue;
+ printk("aio_thread - io_getevents failed, "
+ "errno = %d\n", errno);
+ }
+ else {
+ aio = (struct aio_context *) event.data;
+ if(update_aio(aio, event.res)){
+ do_aio(ctx, aio);
+ continue;
+ }
+
+ reply = ((struct aio_thread_reply)
+ { .data = aio,
+ .err = aio->len });
+ err = os_write_file(aio->reply_fd, &reply,
+ sizeof(reply));
+ if(err != sizeof(reply))
+ printk("aio_thread - write failed, "
+ "fd = %d, err = %d\n", aio->reply_fd,
+ -err);
+ }
+ }
+ return 0;
+}
+
+#endif
+
+static int do_not_aio(struct aio_context *aio)
+{
+ char c;
+ int err;
+
+ switch(aio->type){
+ case AIO_READ:
+ err = os_seek_file(aio->fd, aio->offset);
+ if(err)
+ goto out;
+
+ err = os_read_file(aio->fd, aio->data, aio->len);
+ break;
+ case AIO_WRITE:
+ err = os_seek_file(aio->fd, aio->offset);
+ if(err)
+ goto out;
+
+ err = os_write_file(aio->fd, aio->data, aio->len);
+ break;
+ case AIO_MMAP:
+ err = os_seek_file(aio->fd, aio->offset);
+ if(err)
+ goto out;
+
+ err = os_read_file(aio->fd, &c, sizeof(c));
+ break;
+ default:
+ printk("do_not_aio - bad request type : %d\n", aio->type);
+ err = -EINVAL;
+ break;
+ }
+
+ out:
+ return err;
+}
+
+static int not_aio_thread(void *arg)
+{
+ struct aio_context *aio;
+ struct aio_thread_reply reply;
+ int err;
+
+ signal(SIGWINCH, SIG_IGN);
+ while(1){
+ err = os_read_file(aio_req_fd_r, &aio, sizeof(aio));
+ if(err != sizeof(aio)){
+ if(err < 0)
+ printk("not_aio_thread - read failed, "
+ "fd = %d, err = %d\n", aio_req_fd_r,
+ -err);
+ else {
+ printk("not_aio_thread - short read, fd = %d, "
+ "length = %d\n", aio_req_fd_r, err);
+ }
+ continue;
+ }
+ again:
+ err = do_not_aio(aio);
+
+ if(update_aio(aio, err))
+ goto again;
+
+ reply = ((struct aio_thread_reply) { .data = aio,
+ .err = aio->len });
+ err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
+ if(err != sizeof(reply))
+ printk("not_aio_thread - write failed, fd = %d, "
+ "err = %d\n", aio_req_fd_r, -err);
+ }
+}
+
+static int submit_aio_24(struct aio_context *aio)
+{
+ int err;
+
+ err = os_write_file(aio_req_fd_w, &aio, sizeof(aio));
+ if(err == sizeof(aio))
+ err = 0;
+
+ return err;
+}
+
+static int aio_pid = -1;
+static int (*submit_proc)(struct aio_context *aio);
+
+static int init_aio_24(void)
+{
+ unsigned long stack;
+ int fds[2], err;
+
+ err = os_pipe(fds, 1, 1);
+ if(err)
+ goto out;
+
+ aio_req_fd_w = fds[0];
+ aio_req_fd_r = fds[1];
+ err = run_helper_thread(not_aio_thread, NULL,
+ CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+ if(err < 0)
+ goto out_close_pipe;
+
+ aio_pid = err;
+ goto out;
+
+ out_close_pipe:
+ os_close_file(fds[0]);
+ os_close_file(fds[1]);
+ aio_req_fd_w = -1;
+ aio_req_fd_r = -1;
+ out:
+#ifndef HAVE_AIO_ABI
+ printk("/usr/include/linux/aio_abi.h not present during build\n");
+#endif
+ printk("2.6 host AIO support not used - falling back to I/O "
+ "thread\n");
+
+ submit_proc = submit_aio_24;
+
+ return 0;
+}
+
+#ifdef HAVE_AIO_ABI
+#define DEFAULT_24_AIO 0
+static int submit_aio_26(struct aio_context *aio)
+{
+ struct aio_thread_reply reply;
+ int err;
+
+ err = do_aio(ctx, aio);
+ if(err){
+ reply = ((struct aio_thread_reply) { .data = aio,
+ .err = err });
+ err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
+ if(err != sizeof(reply))
+ printk("submit_aio_26 - write failed, "
+ "fd = %d, err = %d\n", aio->reply_fd, -err);
+ else err = 0;
+ }
+
+ return err;
+}
+
+static int init_aio_26(void)
+{
+ unsigned long stack;
+ int err;
+
+ if(io_setup(256, &ctx)){
+ printk("aio_thread failed to initialize context, err = %d\n",
+ errno);
+ return -errno;
+ }
+
+ err = run_helper_thread(aio_thread, NULL,
+ CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+ if(err < 0)
+ return -errno;
+
+ aio_pid = err;
+
+ printk("Using 2.6 host AIO\n");
+
+ submit_proc = submit_aio_26;
+
+ return 0;
+}
+
+#else
+#define DEFAULT_24_AIO 1
+static int submit_aio_26(struct aio_context *aio)
+{
+ return -ENOSYS;
+}
+
+static int init_aio_26(void)
+{
+ submit_proc = submit_aio_26;
+ return -ENOSYS;
+}
+#endif
+
+static int aio_24 = DEFAULT_24_AIO;
+
+static int __init set_aio_24(char *name, int *add)
+{
+ aio_24 = 1;
+ return 0;
+}
+
+__uml_setup("aio=2.4", set_aio_24,
+"aio=2.4\n"
+" This is used to force UML to use 2.4-style AIO even when 2.6 AIO is\n"
+" available. 2.4 AIO is a single thread that handles one request at a\n"
+" time, synchronously. 2.6 AIO is a thread which uses the 2.6 AIO \n"
+" interface to handle an arbitrary number of pending requests. 2.6 AIO \n"
+" is not available in tt mode, on 2.4 hosts, or when UML is built with\n"
+" /usr/include/linux/aio_abi.h not available. Many distributions don't\n"
+" include aio_abi.h, so you will need to copy it from a kernel tree to\n"
+" your /usr/include/linux in order to build an AIO-capable UML\n\n"
+);
+
+static int init_aio(void)
+{
+ int err;
+
+ CHOOSE_MODE(({
+ if(!aio_24){
+ printk("Disabling 2.6 AIO in tt mode\n");
+ aio_24 = 1;
+ } }), (void) 0);
+
+ if(!aio_24){
+ err = init_aio_26();
+ if(err && (errno == ENOSYS)){
+ printk("2.6 AIO not supported on the host - "
+ "reverting to 2.4 AIO\n");
+ aio_24 = 1;
+ }
+ else return err;
+ }
+
+ if(aio_24)
+ return init_aio_24();
+
+ return 0;
+}
+
+/* The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
+ * needs to be called when the kernel is running because it calls run_helper,
+ * which needs get_free_page. exit_aio is a __uml_exitcall because the generic
+ * kernel does not run __exitcalls on shutdown, and can't because many of them
+ * break when called outside of module unloading.
+ */
+__initcall(init_aio);
+
+static void exit_aio(void)
+{
+ if(aio_pid != -1)
+ os_kill_process(aio_pid, 1);
+}
+
+__uml_exitcall(exit_aio);
+
+int submit_aio(struct aio_context *aio)
+{
+ return (*submit_proc)(aio);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.