diff options
Diffstat (limited to 'kernel/arch/um/os-Linux/aio.c')
| -rw-r--r-- | kernel/arch/um/os-Linux/aio.c | 390 |
1 files changed, 390 insertions, 0 deletions
diff --git a/kernel/arch/um/os-Linux/aio.c b/kernel/arch/um/os-Linux/aio.c new file mode 100644 index 000000000..014eb35fd --- /dev/null +++ b/kernel/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); +} |