/* * QEMU aio implementation * * Copyright IBM, Corp. 2008 * * Authors: * Anthony Liguori <aliguori@us.ibm.com> * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * * Contributions after 2012-01-13 are licensed under the terms of the * GNU GPL, version 2 or (at your option) any later version. */ #include "qemu-common.h" #include "block/block.h" #include "qemu/queue.h" #include "qemu/sockets.h" struct AioHandler { GPollFD pfd; IOHandler *io_read; IOHandler *io_write; AioFlushHandler *io_flush; int deleted; int pollfds_idx; void *opaque; QLIST_ENTRY(AioHandler) node; }; static AioHandler *find_aio_handler(AioContext *ctx, int fd) { AioHandler *node; QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->pfd.fd == fd) if (!node->deleted) return node; } return NULL; } void aio_set_fd_handler(AioContext *ctx, int fd, IOHandler *io_read, IOHandler *io_write, AioFlushHandler *io_flush, void *opaque) { AioHandler *node; node = find_aio_handler(ctx, fd); /* Are we deleting the fd handler? */ if (!io_read && !io_write) { if (node) { g_source_remove_poll(&ctx->source, &node->pfd); /* If the lock is held, just mark the node as deleted */ if (ctx->walking_handlers) { node->deleted = 1; node->pfd.revents = 0; } else { /* Otherwise, delete it for real. We can't just mark it as * deleted because deleted nodes are only cleaned up after * releasing the walking_handlers lock. */ QLIST_REMOVE(node, node); g_free(node); } } } else { if (node == NULL) { /* Alloc and insert if it's not already there */ node = g_malloc0(sizeof(AioHandler)); node->pfd.fd = fd; QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node); g_source_add_poll(&ctx->source, &node->pfd); } /* Update handler with latest information */ node->io_read = io_read; node->io_write = io_write; node->io_flush = io_flush; node->opaque = opaque; node->pollfds_idx = -1; node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0); node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0); } aio_notify(ctx); } void aio_set_event_notifier(AioContext *ctx, EventNotifier *notifier, EventNotifierHandler *io_read, AioFlushEventNotifierHandler *io_flush) { aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), (IOHandler *)io_read, NULL, (AioFlushHandler *)io_flush, notifier); } bool aio_pending(AioContext *ctx) { AioHandler *node; QLIST_FOREACH(node, &ctx->aio_handlers, node) { int revents; revents = node->pfd.revents & node->pfd.events; if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) { return true; } if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) { return true; } } return false; } static bool aio_dispatch(AioContext *ctx) { AioHandler *node; bool progress = false; /* * We have to walk very carefully in case qemu_aio_set_fd_handler is * called while we're walking. */ node = QLIST_FIRST(&ctx->aio_handlers); while (node) { AioHandler *tmp; int revents; ctx->walking_handlers++; revents = node->pfd.revents & node->pfd.events; node->pfd.revents = 0; if (!node->deleted && (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) && node->io_read) { node->io_read(node->opaque); progress = true; } if (!node->deleted && (revents & (G_IO_OUT | G_IO_ERR)) && node->io_write) { node->io_write(node->opaque); progress = true; } tmp = node; node = QLIST_NEXT(node, node); ctx->walking_handlers--; if (!ctx->walking_handlers && tmp->deleted) { QLIST_REMOVE(tmp, node); g_free(tmp); } } return progress; } bool aio_poll(AioContext *ctx, bool blocking) { AioHandler *node; int ret; bool busy, progress; progress = false; /* * If there are callbacks left that have been queued, we need to call them. * Do not call select in this case, because it is possible that the caller * does not need a complete flush (as is the case for qemu_aio_wait loops). */ if (aio_bh_poll(ctx)) { blocking = false; progress = true; } if (aio_dispatch(ctx)) { progress = true; } if (progress && !blocking) { return true; } ctx->walking_handlers++; g_array_set_size(ctx->pollfds, 0); /* fill pollfds */ busy = false; QLIST_FOREACH(node, &ctx->aio_handlers, node) { node->pollfds_idx = -1; /* If there aren't pending AIO operations, don't invoke callbacks. * Otherwise, if there are no AIO requests, qemu_aio_wait() would * wait indefinitely. */ if (!node->deleted && node->io_flush) { if (node->io_flush(node->opaque) == 0) { continue; } busy = true; } if (!node->deleted && node->pfd.events) { GPollFD pfd = { .fd = node->pfd.fd, .events = node->pfd.events, }; node->pollfds_idx = ctx->pollfds->len; g_array_append_val(ctx->pollfds, pfd); } } ctx->walking_handlers--; /* No AIO operations? Get us out of here */ if (!busy) { return progress; } /* wait until next event */ ret = g_poll((GPollFD *)ctx->pollfds->data, ctx->pollfds->len, blocking ? -1 : 0); /* if we have any readable fds, dispatch event */ if (ret > 0) { QLIST_FOREACH(node, &ctx->aio_handlers, node) { if (node->pollfds_idx != -1) { GPollFD *pfd = &g_array_index(ctx->pollfds, GPollFD, node->pollfds_idx); node->pfd.revents = pfd->revents; } } if (aio_dispatch(ctx)) { progress = true; } } assert(progress || busy); return true; }