/* * 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_constants.h" #include "os.h" #include "user.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; signal(SIGWINCH, SIG_IGN); 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; signal(SIGWINCH, SIG_IGN); 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 | SIGCHLD, &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 | SIGCHLD, &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); }