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Diffstat (limited to 'arch/um/os-Linux/aio.c')
-rw-r--r--arch/um/os-Linux/aio.c390
1 files changed, 390 insertions, 0 deletions
diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
new file mode 100644
index 000000000..014eb35fd
--- /dev/null
+++ b/arch/um/os-Linux/aio.c
@@ -0,0 +1,390 @@
+/*
+ * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <unistd.h>
+#include <sched.h>
+#include <signal.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <asm/unistd.h>
+#include <aio.h>
+#include <init.h>
+#include <kern_util.h>
+#include <os.h>
+
+struct aio_thread_req {
+ enum aio_type type;
+ int io_fd;
+ unsigned long long offset;
+ char *buf;
+ int len;
+ struct aio_context *aio;
+};
+
+#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, enum aio_type type, int fd, char *buf,
+ int len, unsigned long long offset, struct aio_context *aio)
+{
+ struct iocb *iocbp = & ((struct iocb) {
+ .aio_data = (unsigned long) aio,
+ .aio_fildes = fd,
+ .aio_buf = (unsigned long) buf,
+ .aio_nbytes = len,
+ .aio_offset = offset
+ });
+ char c;
+
+ switch (type) {
+ case AIO_READ:
+ iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
+ break;
+ case AIO_WRITE:
+ iocbp->aio_lio_opcode = IOCB_CMD_PWRITE;
+ break;
+ case AIO_MMAP:
+ iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
+ iocbp->aio_buf = (unsigned long) &c;
+ iocbp->aio_nbytes = sizeof(c);
+ break;
+ default:
+ printk(UM_KERN_ERR "Bogus op in do_aio - %d\n", type);
+ return -EINVAL;
+ }
+
+ return (io_submit(ctx, 1, &iocbp) > 0) ? 0 : -errno;
+}
+
+/* Initialized in an initcall and unchanged thereafter */
+static aio_context_t ctx = 0;
+
+static int aio_thread(void *arg)
+{
+ struct aio_thread_reply reply;
+ struct io_event event;
+ int err, n, reply_fd;
+
+ os_fix_helper_signals();
+ while (1) {
+ n = io_getevents(ctx, 1, 1, &event, NULL);
+ if (n < 0) {
+ if (errno == EINTR)
+ continue;
+ printk(UM_KERN_ERR "aio_thread - io_getevents failed, "
+ "errno = %d\n", errno);
+ }
+ else {
+ reply = ((struct aio_thread_reply)
+ { .data = (void *) (long) event.data,
+ .err = event.res });
+ reply_fd = ((struct aio_context *) reply.data)->reply_fd;
+ err = write(reply_fd, &reply, sizeof(reply));
+ if (err != sizeof(reply))
+ printk(UM_KERN_ERR "aio_thread - write failed, "
+ "fd = %d, err = %d\n", reply_fd, errno);
+ }
+ }
+ return 0;
+}
+
+#endif
+
+static int do_not_aio(struct aio_thread_req *req)
+{
+ char c;
+ unsigned long long actual;
+ int n;
+
+ actual = lseek64(req->io_fd, req->offset, SEEK_SET);
+ if (actual != req->offset)
+ return -errno;
+
+ switch (req->type) {
+ case AIO_READ:
+ n = read(req->io_fd, req->buf, req->len);
+ break;
+ case AIO_WRITE:
+ n = write(req->io_fd, req->buf, req->len);
+ break;
+ case AIO_MMAP:
+ n = read(req->io_fd, &c, sizeof(c));
+ break;
+ default:
+ printk(UM_KERN_ERR "do_not_aio - bad request type : %d\n",
+ req->type);
+ return -EINVAL;
+ }
+
+ if (n < 0)
+ return -errno;
+ return 0;
+}
+
+/* These are initialized in initcalls and not changed */
+static int aio_req_fd_r = -1;
+static int aio_req_fd_w = -1;
+static int aio_pid = -1;
+static unsigned long aio_stack;
+
+static int not_aio_thread(void *arg)
+{
+ struct aio_thread_req req;
+ struct aio_thread_reply reply;
+ int err;
+
+ os_fix_helper_signals();
+ while (1) {
+ err = read(aio_req_fd_r, &req, sizeof(req));
+ if (err != sizeof(req)) {
+ if (err < 0)
+ printk(UM_KERN_ERR "not_aio_thread - "
+ "read failed, fd = %d, err = %d\n",
+ aio_req_fd_r,
+ errno);
+ else {
+ printk(UM_KERN_ERR "not_aio_thread - short "
+ "read, fd = %d, length = %d\n",
+ aio_req_fd_r, err);
+ }
+ continue;
+ }
+ err = do_not_aio(&req);
+ reply = ((struct aio_thread_reply) { .data = req.aio,
+ .err = err });
+ err = write(req.aio->reply_fd, &reply, sizeof(reply));
+ if (err != sizeof(reply))
+ printk(UM_KERN_ERR "not_aio_thread - write failed, "
+ "fd = %d, err = %d\n", req.aio->reply_fd, errno);
+ }
+
+ return 0;
+}
+
+static int init_aio_24(void)
+{
+ 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 = os_set_fd_block(aio_req_fd_w, 0);
+ if (err)
+ goto out_close_pipe;
+
+ err = run_helper_thread(not_aio_thread, NULL,
+ CLONE_FILES | CLONE_VM, &aio_stack);
+ if (err < 0)
+ goto out_close_pipe;
+
+ aio_pid = err;
+ goto out;
+
+out_close_pipe:
+ close(fds[0]);
+ close(fds[1]);
+ aio_req_fd_w = -1;
+ aio_req_fd_r = -1;
+out:
+#ifndef HAVE_AIO_ABI
+ printk(UM_KERN_INFO "/usr/include/linux/aio_abi.h not present during "
+ "build\n");
+#endif
+ printk(UM_KERN_INFO "2.6 host AIO support not used - falling back to "
+ "I/O thread\n");
+ return 0;
+}
+
+#ifdef HAVE_AIO_ABI
+#define DEFAULT_24_AIO 0
+static int init_aio_26(void)
+{
+ int err;
+
+ if (io_setup(256, &ctx)) {
+ err = -errno;
+ printk(UM_KERN_ERR "aio_thread failed to initialize context, "
+ "err = %d\n", errno);
+ return err;
+ }
+
+ err = run_helper_thread(aio_thread, NULL,
+ CLONE_FILES | CLONE_VM, &aio_stack);
+ if (err < 0)
+ return err;
+
+ aio_pid = err;
+
+ printk(UM_KERN_INFO "Using 2.6 host AIO\n");
+ return 0;
+}
+
+static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
+ unsigned long long offset, struct aio_context *aio)
+{
+ struct aio_thread_reply reply;
+ int err;
+
+ err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
+ if (err) {
+ reply = ((struct aio_thread_reply) { .data = aio,
+ .err = err });
+ err = write(aio->reply_fd, &reply, sizeof(reply));
+ if (err != sizeof(reply)) {
+ err = -errno;
+ printk(UM_KERN_ERR "submit_aio_26 - write failed, "
+ "fd = %d, err = %d\n", aio->reply_fd, -err);
+ }
+ else err = 0;
+ }
+
+ return err;
+}
+
+#else
+#define DEFAULT_24_AIO 1
+static int init_aio_26(void)
+{
+ return -ENOSYS;
+}
+
+static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
+ unsigned long long offset, struct aio_context *aio)
+{
+ return -ENOSYS;
+}
+#endif
+
+/* Initialized in an initcall and unchanged thereafter */
+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;
+
+ if (!aio_24) {
+ err = init_aio_26();
+ if (err && (errno == ENOSYS)) {
+ printk(UM_KERN_INFO "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);
+ free_stack(aio_stack, 0);
+ }
+}
+
+__uml_exitcall(exit_aio);
+
+static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
+ unsigned long long offset, struct aio_context *aio)
+{
+ struct aio_thread_req req = { .type = type,
+ .io_fd = io_fd,
+ .offset = offset,
+ .buf = buf,
+ .len = len,
+ .aio = aio,
+ };
+ int err;
+
+ err = write(aio_req_fd_w, &req, sizeof(req));
+ if (err == sizeof(req))
+ err = 0;
+ else err = -errno;
+
+ return err;
+}
+
+int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
+ unsigned long long offset, int reply_fd,
+ struct aio_context *aio)
+{
+ aio->reply_fd = reply_fd;
+ if (aio_24)
+ return submit_aio_24(type, io_fd, buf, len, offset, aio);
+ else
+ return submit_aio_26(type, io_fd, buf, len, offset, aio);
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-03 22:29:00 +0000