--- /dev/null
+/*
+ * Copyright (c) 2010, XenSource Inc.
+ * All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA
+ */
+
+/*
+ * kernel 2.6.21 added eventfd(2) support, kernel 2.6.22 eventfds for
+ * aio. libaio 0.3.107 updated the header file, but few systems have
+ * it. define a custom iocb_common struct instead, and work around a
+ * potentially missing sys/eventfd.h. this header should vanish over
+ * time.
+ */
+
+#ifndef __LIBAIO_COMPAT
+#define __LIBAIO_COMPAT
+
+#include <libaio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+struct __compat_io_iocb_common {
+ char __pad_buf[8];
+ char __pad_nbytes[8];
+ long long offset;
+ long long __pad3;
+ unsigned flags;
+ unsigned resfd;
+};
+
+static inline void __io_set_eventfd(struct iocb *iocb, int eventfd)
+{
+ struct __compat_io_iocb_common *c;
+ c = (struct __compat_io_iocb_common*)&iocb->u.c;
+ c->flags |= (1 << 0);
+ c->resfd = eventfd;
+}
+
+#ifndef SYS_eventfd
+#ifndef __NR_eventfd
+# if defined(__alpha__)
+# define __NR_eventfd 478
+# elif defined(__arm__)
+# define __NR_eventfd (__NR_SYSCALL_BASE+351)
+# elif defined(__ia64__)
+# define __NR_eventfd 1309
+# elif defined(__i386__)
+# define __NR_eventfd 323
+# elif defined(__m68k__)
+# define __NR_eventfd 319
+# elif 0 && defined(__mips__)
+# error __NR_eventfd?
+# define __NR_eventfd (__NR_Linux + 319)
+# define __NR_eventfd (__NR_Linux + 278)
+# define __NR_eventfd (__NR_Linux + 282)
+# elif defined(__hppa__)
+# define __NR_eventfd (__NR_Linux + 304)
+# elif defined(__PPC__) || defined(__powerpc64__)
+# define __NR_eventfd 307
+# elif defined(__s390__) || defined(__s390x__)
+# define __NR_eventfd 318
+# elif defined(__sparc__)
+# define __NR_eventfd 313
+# elif defined(__x86_64__)
+# define __NR_eventfd 284
+# endif
+#else
+# error __NR_eventfd?
+#endif
+#define SYS_eventfd __NR_eventfd
+#endif
+
+static inline int tapdisk_sys_eventfd(int initval)
+{
+ return syscall(SYS_eventfd, initval, 0);
+}
+
+#endif /* __LIBAIO_COMPAT */
#include <stdlib.h>
#include <unistd.h>
#include <libaio.h>
+#ifdef __linux__
+#include <linux/version.h>
+#endif
#include "tapdisk.h"
#include "tapdisk-log.h"
#include "tapdisk-queue.h"
#include "tapdisk-filter.h"
#include "tapdisk-server.h"
+#include "tapdisk-utils.h"
+
+#include "libaio-compat.h"
#include "atomicio.h"
#define WARN(_f, _a...) tlog_write(TLOG_WARN, _f, ##_a)
io_context_t aio_ctx;
struct io_event *aio_events;
- int poll_fd;
+ int event_fd;
int event_id;
+
+ int flags;
};
+#define LIO_FLAG_EVENTFD (1<<0)
+
+static int
+tapdisk_lio_check_resfd(void)
+{
+ return tapdisk_linux_version() >= KERNEL_VERSION(2, 6, 22);
+}
+
+static void
+tapdisk_lio_destroy_aio(struct tqueue *queue)
+{
+ struct lio *lio = queue->tio_data;
+
+ if (lio->event_fd >= 0) {
+ close(lio->event_fd);
+ lio->event_fd = -1;
+ }
+
+ if (lio->aio_ctx) {
+ io_destroy(lio->aio_ctx);
+ lio->aio_ctx = 0;
+ }
+}
+
+static int
+__lio_setup_aio_poll(struct tqueue *queue, int qlen)
+{
+ struct lio *lio = queue->tio_data;
+ int err, fd;
+
+ lio->aio_ctx = REQUEST_ASYNC_FD;
+
+ fd = io_setup(qlen, &lio->aio_ctx);
+ if (fd < 0) {
+ lio->aio_ctx = 0;
+ err = -errno;
+
+ if (err == -EINVAL)
+ goto fail_fd;
+
+ goto fail;
+ }
+
+ lio->event_fd = fd;
+
+ return 0;
+
+fail_fd:
+ DPRINTF("Couldn't get fd for AIO poll support. This is probably "
+ "because your kernel does not have the aio-poll patch "
+ "applied.\n");
+fail:
+ return err;
+}
+
+static int
+__lio_setup_aio_eventfd(struct tqueue *queue, int qlen)
+{
+ struct lio *lio = queue->tio_data;
+ int err;
+
+ err = io_setup(qlen, &lio->aio_ctx);
+ if (err < 0) {
+ lio->aio_ctx = 0;
+ return err;
+ }
+
+ lio->event_fd = tapdisk_sys_eventfd(0);
+ if (lio->event_fd < 0)
+ return -errno;
+
+ lio->flags |= LIO_FLAG_EVENTFD;
+
+ return 0;
+}
+
+static int
+tapdisk_lio_setup_aio(struct tqueue *queue, int qlen)
+{
+ struct lio *lio = queue->tio_data;
+ int err;
+
+ lio->aio_ctx = 0;
+ lio->event_fd = -1;
+
+ /*
+ * prefer the mainline eventfd(2) api, if available.
+ * if not, fall back to the poll fd patch.
+ */
+
+ err = !tapdisk_lio_check_resfd();
+ if (!err)
+ err = __lio_setup_aio_eventfd(queue, qlen);
+ if (err)
+ err = __lio_setup_aio_poll(queue, qlen);
+
+ if (err == -EAGAIN)
+ goto fail_rsv;
+fail:
+ return err;
+
+fail_rsv:
+ DPRINTF("Couldn't setup AIO context. If you are trying to "
+ "concurrently use a large number of blktap-based disks, you may "
+ "need to increase the system-wide aio request limit. "
+ "(e.g. 'echo 1048576 > /proc/sys/fs/aio-max-nr')\n");
+ goto fail;
+}
+
+
static void
tapdisk_lio_destroy(struct tqueue *queue)
{
lio->event_id = -1;
}
- if (lio->aio_ctx) {
- io_destroy(lio->aio_ctx);
- lio->aio_ctx = NULL;
- }
+ tapdisk_lio_destroy_aio(queue);
if (lio->aio_events) {
free(lio->aio_events);
}
}
+static void
+tapdisk_lio_set_eventfd(struct tqueue *queue, int n, struct iocb **iocbs)
+{
+ struct lio *lio = queue->tio_data;
+ int i;
+
+ if (lio->flags & LIO_FLAG_EVENTFD)
+ for (i = 0; i < n; ++i)
+ __io_set_eventfd(iocbs[i], lio->event_fd);
+}
+
+static void
+tapdisk_lio_ack_event(struct tqueue *queue)
+{
+ struct lio *lio = queue->tio_data;
+ uint64_t val;
+
+ if (lio->flags & LIO_FLAG_EVENTFD)
+ read(lio->event_fd, &val, sizeof(val));
+}
+
static void
tapdisk_lio_event(event_id_t id, char mode, void *private)
{
struct tiocb *tiocb;
struct io_event *ep;
+ tapdisk_lio_ack_event(queue);
+
lio = queue->tio_data;
ret = io_getevents(lio->aio_ctx, 0,
queue->size, lio->aio_events, NULL);
int err;
lio->event_id = -1;
- lio->aio_ctx = REQUEST_ASYNC_FD;
-
- lio->poll_fd = io_setup(qlen, &lio->aio_ctx);
- err = lio->poll_fd;
- if (err < 0) {
- lio->aio_ctx = NULL;
- if (err == -EAGAIN)
- goto fail_rsv;
-
- goto fail_fd;
- }
+ err = tapdisk_lio_setup_aio(queue, qlen);
+ if (err)
+ goto fail;
lio->event_id =
tapdisk_server_register_event(SCHEDULER_POLL_READ_FD,
- lio->poll_fd, 0,
+ lio->event_fd, 0,
tapdisk_lio_event,
queue);
err = lio->event_id;
fail:
tapdisk_lio_destroy(queue);
return err;
-
-fail_rsv:
- DPRINTF("Couldn't setup AIO context. If you are trying to "
- "concurrently use a large number of blktap-based disks, you may "
- "need to increase the system-wide aio request limit. "
- "(e.g. 'echo 1048576 > /proc/sys/fs/aio-max-nr')\n");
- goto fail;
-
-fail_fd:
- DPRINTF("Couldn't get fd for AIO poll support. This is probably "
- "because your kernel does not have the aio-poll patch "
- "applied.\n");
- goto fail;
}
static int
tapdisk_filter_iocbs(queue->filter, queue->iocbs, queue->queued);
merged = io_merge(&queue->opioctx, queue->iocbs, queue->queued);
+ tapdisk_lio_set_eventfd(queue, merged, queue->iocbs);
submitted = io_submit(lio->aio_ctx, merged, queue->iocbs);
DBG("queued: %d, merged: %d, submitted: %d\n",
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