From 0fb4bc4ef230ee05ae5e04f841121e8501773577 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Tue, 17 Apr 2012 17:56:02 -0700
Subject: [PATCH] Add vfs_aio_linux module.

---
 docs-xml/manpages-3/vfs_aio_linux.8.xml |  115 +++++
 source3/Makefile.in                     |    5 +
 source3/configure.in                    |   15 +
 source3/modules/vfs_aio_linux.c         |  755 +++++++++++++++++++++++++++++++
 4 files changed, 890 insertions(+), 0 deletions(-)
 create mode 100644 docs-xml/manpages-3/vfs_aio_linux.8.xml
 create mode 100644 source3/modules/vfs_aio_linux.c

diff --git a/docs-xml/manpages-3/vfs_aio_linux.8.xml b/docs-xml/manpages-3/vfs_aio_linux.8.xml
new file mode 100644
index 0000000..dac94a5
--- /dev/null
+++ b/docs-xml/manpages-3/vfs_aio_linux.8.xml
@@ -0,0 +1,115 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
+<refentry id="vfs_aio_linux.8">
+
+<refmeta>
+	<refentrytitle>vfs_aio_linux</refentrytitle>
+	<manvolnum>8</manvolnum>
+	<refmiscinfo class="source">Samba</refmiscinfo>
+	<refmiscinfo class="manual">System Administration tools</refmiscinfo>
+	<refmiscinfo class="version">3.6</refmiscinfo>
+</refmeta>
+
+
+<refnamediv>
+	<refname>vfs_aio_linux</refname>
+	<refpurpose>implement async I/O in Samba vfs using Linux kernel aio calls</refpurpose>
+</refnamediv>
+
+<refsynopsisdiv>
+	<cmdsynopsis>
+		<command>vfs objects = aio_linux</command>
+	</cmdsynopsis>
+</refsynopsisdiv>
+
+<refsect1>
+	<title>DESCRIPTION</title>
+
+	<para>This VFS module is part of the
+	<citerefentry><refentrytitle>samba</refentrytitle>
+	<manvolnum>7</manvolnum></citerefentry> suite.</para>
+
+	<para>The <command>aio_linux</command> VFS module enables asynchronous
+	I/O for Samba on Linux kernels that have the kernel AIO calls available
+	without using the Posix AIO interface. Posix AIO can suffer from severe
+	limitations.  For example, on some Linux versions the
+	real-time signals that it uses are broken under heavy load.
+	Other systems only allow AIO when special kernel modules are
+	loaded or only allow a certain system-wide amount of async
+	requests being scheduled. Systems based on glibc (most Linux
+	systems) only allow a single outstanding request per file
+	descriptor which essentially makes Posix AIO useless on systems
+	using the glibc implementation.</para>
+
+	<para>To work around all these limitations, the aio_linux module
+	was written. It uses the Linux kernel AIO interface instead of the
+	internal Posix AIO interface to allow read and write calls
+	to be processed asynchronously. A queue size of 128 events
+	is used by default. To change this limit set the "aio num events"
+	parameter below.
+	</para>
+
+	<para>
+	Note that the smb.conf parameters <command>aio read size</command>
+	and <command>aio write size</command> must also be set appropriately
+	for this module to be active.
+	</para>
+
+	<para>This module MUST be listed last in any module stack as
+	the Samba VFS pread/pwrite interface is not thread-safe. This
+	module makes direct pread and pwrite system calls and does
+	NOT call the Samba VFS pread and pwrite interfaces.</para>
+
+</refsect1>
+
+
+<refsect1>
+	<title>EXAMPLES</title>
+
+	<para>Straight forward use:</para>
+
+<programlisting>
+        <smbconfsection name="[cooldata]"/>
+	<smbconfoption name="path">/data/ice</smbconfoption>
+	<smbconfoption name="aio read size">1024</smbconfoption>
+	<smbconfoption name="aio write size">1024</smbconfoption>
+	<smbconfoption name="vfs objects">aio_linux</smbconfoption>
+</programlisting>
+
+</refsect1>
+
+<refsect1>
+	<title>OPTIONS</title>
+
+	<variablelist>
+
+		<varlistentry>
+		<term>aio_linux:aio num events = INTEGER</term>
+		<listitem>
+		<para>Set the maximum size of the event queue
+		that is used to limit outstanding IO requests.
+		</para>
+		<para>By default this is set to 128.</para>
+		</listitem>
+		</varlistentry>
+
+	</variablelist>
+</refsect1>
+<refsect1>
+	<title>VERSION</title>
+
+	<para>This man page is correct for version 3.6.6 of the Samba suite.
+	</para>
+</refsect1>
+
+<refsect1>
+	<title>AUTHOR</title>
+
+	<para>The original Samba software and related utilities
+	were created by Andrew Tridgell. Samba is now developed
+	by the Samba Team as an Open Source project similar
+	to the way the Linux kernel is developed.</para>
+
+</refsect1>
+
+</refentry>
diff --git a/source3/Makefile.in b/source3/Makefile.in
index 007c82d..1b0d4b1 100644
--- a/source3/Makefile.in
+++ b/source3/Makefile.in
@@ -830,6 +830,7 @@ VFS_TSMSM_OBJ = modules/vfs_tsmsm.o
 VFS_FILEID_OBJ = modules/vfs_fileid.o
 VFS_AIO_FORK_OBJ = modules/vfs_aio_fork.o
 VFS_AIO_PTHREAD_OBJ = modules/vfs_aio_pthread.o
+VFS_AIO_LINUX_OBJ = modules/vfs_aio_linux.o
 VFS_PREOPEN_OBJ = modules/vfs_preopen.o
 VFS_SYNCOPS_OBJ = modules/vfs_syncops.o
 VFS_ACL_XATTR_OBJ = modules/vfs_acl_xattr.o
@@ -3034,6 +3035,10 @@ bin/aio_pthread.@SHLIBEXT@: $(BINARY_PREREQS) $(VFS_AIO_PTHREAD_OBJ) lib/pthread
 	@echo "Building plugin $@"
 	@$(SHLD_MODULE) $(VFS_AIO_PTHREAD_OBJ) lib/pthreadpool/pthreadpool.o -lpthread
 
+bin/aio_linux.@SHLIBEXT@: $(BINARY_PREREQS) $(VFS_AIO_LINUX_OBJ)
+	@echo "Building plugin $@"
+	@$(SHLD_MODULE) $(VFS_AIO_LINUX_OBJ)
+
 bin/preopen.@SHLIBEXT@: $(BINARY_PREREQS) $(VFS_PREOPEN_OBJ)
 	@echo "Building plugin $@"
 	@$(SHLD_MODULE) $(VFS_PREOPEN_OBJ)
diff --git a/source3/configure.in b/source3/configure.in
index 061c1b1..3e2e743 100644
--- a/source3/configure.in
+++ b/source3/configure.in
@@ -5882,6 +5882,20 @@ if test x"$samba_cv_HAVE_AIO" = x"yes"; then
 		x"$samba_cv_msghdr_msg_acctright" = x"yes"; then
 		default_shared_modules="$default_shared_modules vfs_aio_fork"
 	fi
+# Check for Linux kernel aio support.
+        case "$host_os" in
+        *linux*)
+            AC_MSG_CHECKING(for Linux kernel asynchronous io support)
+            AC_CHECK_LIB(aio,io_submit,
+                [AIO_LIBS="$LIBS -laio";
+                AC_DEFINE(HAVE_LINUX_KERNEL_AIO, 1, Define to 1 if there is support for Linux kernel asynchronous io)],
+                [])
+            if test x"$ac_cv_lib_aio_io_submit" = x"yes"; then
+                default_shared_modules="$default_shared_modules vfs_aio_linux"
+            fi
+            ;;
+        esac
+
 fi
 
 #################################################
@@ -6896,6 +6910,7 @@ SMB_MODULE(vfs_tsmsm, \$(VFS_TSMSM_OBJ), "bin/tsmsm.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_fileid, \$(VFS_FILEID_OBJ), "bin/fileid.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_aio_fork, \$(VFS_AIO_FORK_OBJ), "bin/aio_fork.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_aio_pthread, \$(VFS_AIO_PTHREAD_OBJ), "bin/aio_pthread.$SHLIBEXT", VFS)
+SMB_MODULE(vfs_aio_linux, \$(VFS_AIO_LINUX_OBJ), "bin/aio_linux.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_preopen, \$(VFS_PREOPEN_OBJ), "bin/preopen.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_syncops, \$(VFS_SYNCOPS_OBJ), "bin/syncops.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_zfsacl, \$(VFS_ZFSACL_OBJ), "bin/zfsacl.$SHLIBEXT", VFS)
diff --git a/source3/modules/vfs_aio_linux.c b/source3/modules/vfs_aio_linux.c
new file mode 100644
index 0000000..1844a7e
--- /dev/null
+++ b/source3/modules/vfs_aio_linux.c
@@ -0,0 +1,755 @@
+/*
+ * Simulate Posix AIO using Linux kernel AIO.
+ *
+ * Copyright (C) Jeremy Allison 2012
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "includes.h"
+#include "system/filesys.h"
+#include "smbd/smbd.h"
+#include "smbd/globals.h"
+#include <sys/eventfd.h>
+#include <libaio.h>
+
+struct aio_extra;
+static int event_fd = -1;
+static io_context_t io_ctx;
+static int aio_linux_requestid;
+static struct io_event *io_recv_events;
+static struct fd_event *aio_read_event;
+
+struct aio_private_data {
+	struct aio_private_data *prev, *next;
+	int requestid;
+	SMB_STRUCT_AIOCB *aiocb;
+	struct iocb *event_iocb;
+	ssize_t ret_size;
+	int ret_errno;
+	bool cancelled;
+};
+
+/* List of outstanding requests we have. */
+static struct aio_private_data *pd_list;
+
+static void aio_linux_handle_completion(struct event_context *event_ctx,
+			struct fd_event *event,
+			uint16 flags,
+			void *p);
+
+/************************************************************************
+ Housekeeping. Cleanup if no activity for 30 seconds.
+***********************************************************************/
+
+static void aio_linux_housekeeping(struct tevent_context *event_ctx,
+                                        struct tevent_timer *te,
+                                        struct timeval now,
+                                        void *private_data)
+{
+	/* Remove this timed event handler. */
+	TALLOC_FREE(te);
+
+	if (pd_list != NULL) {
+		/* Still busy. Look again in 30 seconds. */
+		(void)tevent_add_timer(event_ctx,
+					NULL,
+					timeval_current_ofs(30, 0),
+					aio_linux_housekeeping,
+					NULL);
+		return;
+	}
+
+	/* No activity for 30 seconds. Close out kernel resources. */
+	io_queue_release(io_ctx);
+	memset(&io_ctx, '\0', sizeof(io_ctx));
+
+	if (event_fd != -1) {
+		close(event_fd);
+		event_fd = -1;
+	}
+
+	TALLOC_FREE(aio_read_event);
+	TALLOC_FREE(io_recv_events);
+}
+
+/************************************************************************
+ Ensure event fd and aio context are initialized.
+***********************************************************************/
+
+static bool init_aio_linux(struct vfs_handle_struct *handle)
+{
+	struct tevent_timer *te = NULL;
+
+	if (event_fd != -1) {
+		/* Already initialized. */
+		return true;
+	}
+
+	/* Schedule a shutdown event for 30 seconds from now. */
+	te = tevent_add_timer(server_event_context(),
+				NULL,
+				timeval_current_ofs(30, 0),
+				aio_linux_housekeeping,
+				NULL);
+
+	if (te == NULL) {
+		goto fail;
+	}
+
+	/* Ensure we have enough space for aio_pending_size events. */
+	io_recv_events = talloc_zero_array(NULL,
+				struct io_event,
+				aio_pending_size);
+	if (io_recv_events == NULL) {
+		goto fail;
+	}
+
+	event_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+	if (event_fd == -1) {
+		goto fail;
+	}
+
+	aio_read_event = tevent_add_fd(server_event_context(),
+				NULL,
+				event_fd,
+				TEVENT_FD_READ,
+				aio_linux_handle_completion,
+				NULL);
+	if (aio_read_event == NULL) {
+		goto fail;
+	}
+
+	if (io_queue_init(aio_pending_size, &io_ctx)) {
+		goto fail;
+	}
+
+	DEBUG(10,("init_aio_linux: initialized with up to %d events\n",
+		  aio_pending_size));
+
+	return true;
+
+  fail:
+
+	DEBUG(10,("init_aio_linux: initialization failed\n"));
+
+	TALLOC_FREE(te);
+	TALLOC_FREE(io_recv_events);
+	TALLOC_FREE(aio_read_event);
+	if (event_fd != -1) {
+		close(event_fd);
+		event_fd = -1;
+	}
+	memset(&io_ctx, '\0', sizeof(io_ctx));
+	return false;
+}
+
+/************************************************************************
+ Private data destructor.
+***********************************************************************/
+
+static int pd_destructor(struct aio_private_data *pd)
+{
+	DLIST_REMOVE(pd_list, pd);
+	return 0;
+}
+
+/************************************************************************
+ Create and initialize a private data struct.
+***********************************************************************/
+
+static struct aio_private_data *create_private_data(TALLOC_CTX *ctx,
+					SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_private_data *pd = talloc_zero(ctx, struct aio_private_data);
+	if (!pd) {
+		return NULL;
+	}
+	pd->event_iocb = talloc_zero(pd, struct iocb);
+	pd->requestid = aio_linux_requestid++;
+	pd->aiocb = aiocb;
+	pd->ret_size = -1;
+	pd->ret_errno = EINPROGRESS;
+	talloc_set_destructor(pd, pd_destructor);
+	DLIST_ADD_END(pd_list, pd, struct aio_private_data *);
+	return pd;
+}
+
+/************************************************************************
+ Initiate an asynchronous pread call.
+***********************************************************************/
+
+static int aio_linux_read(struct vfs_handle_struct *handle,
+				struct files_struct *fsp,
+				SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_extra *aio_ex = (struct aio_extra *)aiocb->aio_sigevent.sigev_value.sival_ptr;
+	struct aio_private_data *pd = NULL;
+	int ret;
+
+	if (!init_aio_linux(handle)) {
+		return -1;
+	}
+
+	pd = create_private_data(aio_ex, aiocb);
+	if (pd == NULL) {
+		DEBUG(10, ("aio_linux_read: Could not create private data.\n"));
+		return -1;
+	}
+
+	io_prep_pread(pd->event_iocb,
+			pd->aiocb->aio_fildes,
+			discard_const(pd->aiocb->aio_buf),
+			pd->aiocb->aio_nbytes,
+			pd->aiocb->aio_offset);
+	io_set_eventfd(pd->event_iocb, event_fd);
+	/* Use the callback pointer as a private data ptr. */
+	io_set_callback(pd->event_iocb, (io_callback_t)pd);
+
+	ret = io_submit(io_ctx, 1, &pd->event_iocb);
+	if (ret < 0) {
+		errno = ret;
+		return -1;
+	}
+
+	DEBUG(10, ("aio_linux_read: requestid=%d read requested "
+		"of %llu bytes at offset %llu\n",
+		pd->requestid,
+		(unsigned long long)pd->aiocb->aio_nbytes,
+		(unsigned long long)pd->aiocb->aio_offset));
+
+	return 0;
+}
+
+/************************************************************************
+ Initiate an asynchronous pwrite call.
+***********************************************************************/
+
+static int aio_linux_write(struct vfs_handle_struct *handle,
+				struct files_struct *fsp,
+				SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_extra *aio_ex = (struct aio_extra *)aiocb->aio_sigevent.sigev_value.sival_ptr;
+	struct aio_private_data *pd = NULL;
+	int ret;
+
+	if (!init_aio_linux(handle)) {
+		return -1;
+	}
+
+	pd = create_private_data(aio_ex, aiocb);
+	if (pd == NULL) {
+		DEBUG(10, ("aio_linux_write: Could not create private data.\n"));
+		return -1;
+	}
+
+	io_prep_pwrite(pd->event_iocb,
+			pd->aiocb->aio_fildes,
+			discard_const(pd->aiocb->aio_buf),
+			pd->aiocb->aio_nbytes,
+			pd->aiocb->aio_offset);
+	io_set_eventfd(pd->event_iocb, event_fd);
+	/* Use the callback pointer as a private data ptr. */
+	io_set_callback(pd->event_iocb, (io_callback_t)pd);
+
+	ret = io_submit(io_ctx, 1, &pd->event_iocb);
+	if (ret < 0) {
+		errno = ret;
+		return -1;
+	}
+
+	DEBUG(10, ("aio_linux_write: requestid=%d pwrite requested "
+		"of %llu bytes at offset %llu\n",
+		pd->requestid,
+		(unsigned long long)pd->aiocb->aio_nbytes,
+		(unsigned long long)pd->aiocb->aio_offset));
+
+	return 0;
+}
+
+/************************************************************************
+ Save off the error / success conditions from the io_event.
+ Is idempotent (can be called multiple times given the same ioev).
+***********************************************************************/
+
+static void aio_linux_setup_returns(struct io_event *ioev)
+{
+	struct aio_private_data *pd = (struct aio_private_data *)ioev->data;
+
+	/* ioev->res2 contains the -errno if error. */
+	/* ioev->res contains the number of bytes sent/received. */
+	if (ioev->res2) {
+		pd->ret_size = -1;
+		pd->ret_errno = -ioev->res2;
+	} else {
+		pd->ret_size = ioev->res;
+		pd->ret_errno = 0;
+	}
+}
+
+/************************************************************************
+ Handle a single finished io.
+***********************************************************************/
+
+static void aio_linux_handle_io_finished(struct io_event *ioev)
+{
+	struct aio_extra *aio_ex = NULL;
+	struct aio_private_data *pd = (struct aio_private_data *)ioev->data;
+
+	aio_linux_setup_returns(ioev);
+
+	aio_ex = (struct aio_extra *)pd->aiocb->aio_sigevent.sigev_value.sival_ptr;
+	smbd_aio_complete_aio_ex(aio_ex);
+
+	DEBUG(10,("aio_linux_handle_io_finished: requestid %d completed\n",
+		pd->requestid ));
+	TALLOC_FREE(aio_ex);
+}
+
+/************************************************************************
+ Callback when multiple IOs complete.
+***********************************************************************/
+
+static void aio_linux_handle_completion(struct event_context *event_ctx,
+				struct fd_event *event,
+				uint16 flags,
+				void *p)
+{
+	uint64_t num_events = 0;
+
+	DEBUG(10, ("aio_linux_handle_completion called with flags=%d\n",
+			(int)flags));
+
+	if ((flags & EVENT_FD_READ) == 0) {
+		return;
+	}
+
+	/* Read the number of events available. */
+	if (sys_read(event_fd, &num_events, sizeof(num_events)) !=
+			sizeof(num_events)) {
+		smb_panic("aio_linux_handle_completion: invalid read");
+	}
+
+	while (num_events > 0) {
+		uint64_t events_to_read = MIN(num_events, aio_pending_size);
+		struct timespec ts;
+		int i;
+		int ret;
+
+		ts.tv_sec = 0;
+		ts.tv_nsec = 0;
+
+		ret = io_getevents(io_ctx,
+			1,
+			(long)events_to_read,
+			io_recv_events,
+			&ts);
+
+		if (ret < 0) {
+			errno = -ret;
+			DEBUG(1, ("aio_linux_handle_completion: "
+				"io_getevents error %s\n",
+				strerror(errno) ));
+			return;
+		}
+
+		if (ret == 0) {
+			DEBUG(10, ("aio_linux_handle_completion: "
+				"io_getevents returned 0\n"));
+			continue;
+		}
+
+		/* ret is positive. */
+		for (i = 0; i < ret; i++) {
+			aio_linux_handle_io_finished(&io_recv_events[i]);
+		}
+
+		num_events -= ret;
+	}
+}
+
+/************************************************************************
+ Find the private data by aiocb.
+***********************************************************************/
+
+static struct aio_private_data *find_private_data_by_aiocb(SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_private_data *pd;
+
+	for (pd = pd_list; pd != NULL; pd = pd->next) {
+		if (pd->aiocb == aiocb) {
+			return pd;
+		}
+	}
+
+	return NULL;
+}
+
+/************************************************************************
+ Called to return the result of a completed AIO.
+ Should only be called if aio_error returns something other than EINPROGRESS.
+ Returns:
+	Any other value - return from IO operation.
+***********************************************************************/
+
+static ssize_t aio_linux_return_fn(struct vfs_handle_struct *handle,
+				struct files_struct *fsp,
+				SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_private_data *pd = find_private_data_by_aiocb(aiocb);
+
+	if (pd == NULL) {
+		errno = EINVAL;
+		DEBUG(0, ("aio_linux_return_fn: returning EINVAL\n"));
+		return -1;
+	}
+
+	pd->aiocb = NULL;
+
+	if (pd->cancelled) {
+		errno = ECANCELED;
+		return -1;
+	}
+
+	if (pd->ret_size == -1) {
+		errno = pd->ret_errno;
+	}
+
+	return pd->ret_size;
+}
+
+/************************************************************************
+ Called to check the result of an AIO.
+ Returns:
+	EINPROGRESS - still in progress.
+	EINVAL - invalid aiocb.
+	ECANCELED - request was cancelled.
+	0 - request completed successfully.
+	Any other value - errno from IO operation.
+***********************************************************************/
+
+static int aio_linux_error_fn(struct vfs_handle_struct *handle,
+			     struct files_struct *fsp,
+			     SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_private_data *pd = find_private_data_by_aiocb(aiocb);
+
+	if (pd == NULL) {
+		return EINVAL;
+	}
+	if (pd->cancelled) {
+		return ECANCELED;
+	}
+	return pd->ret_errno;
+}
+
+/************************************************************************
+ Called to request the cancel of an AIO, or all of them on a specific
+ fsp if aiocb == NULL.
+***********************************************************************/
+
+static int aio_linux_cancel(struct vfs_handle_struct *handle,
+			struct files_struct *fsp,
+			SMB_STRUCT_AIOCB *aiocb)
+{
+	struct aio_private_data *pd = NULL;
+
+	for (pd = pd_list; pd != NULL; pd = pd->next) {
+		if (pd->aiocb == NULL) {
+			continue;
+		}
+		if (pd->aiocb->aio_fildes != fsp->fh->fd) {
+			continue;
+		}
+		if ((aiocb != NULL) && (pd->aiocb != aiocb)) {
+			continue;
+		}
+
+		/*
+		 * We let the kernel do its job, but we discard the result when
+		 * it's finished. NB. Should I call io_cancel here ?
+		 */
+
+		pd->cancelled = true;
+	}
+
+	return AIO_CANCELED;
+}
+
+/************************************************************************
+ Callback for a previously detected job completion deferred to the main
+ loop.
+***********************************************************************/
+
+static void aio_linux_handle_immediate(struct tevent_context *ctx,
+				struct tevent_immediate *im,
+				void *private_data)
+{
+	struct io_event *ioev = (struct io_event *)private_data;
+
+	aio_linux_handle_io_finished(ioev);
+	TALLOC_FREE(ioev);
+}
+
+/************************************************************************
+ Private data struct used in suspend completion code.
+***********************************************************************/
+
+struct suspend_private {
+	int num_entries;
+	int num_finished;
+	const SMB_STRUCT_AIOCB * const *aiocb_array;
+};
+
+/************************************************************************
+ Handle a single finished io from suspend.
+***********************************************************************/
+
+static void aio_linux_handle_suspend_io_finished(struct suspend_private *sp,
+						struct io_event *ioev)
+{
+	struct aio_private_data *pd = (struct aio_private_data *)ioev->data;
+	struct io_event *new_ioev = NULL;
+	struct tevent_immediate *im = NULL;
+	int i;
+
+	/* Is this a requestid with an aiocb we're interested in ? */
+	for (i = 0; i < sp->num_entries; i++) {
+		if (sp->aiocb_array[i] == pd->aiocb) {
+			sp->num_finished++;
+			/*
+			 * We don't call aio_linux_handle_io_finished()
+			 * here, but only the function that sets up the
+			 * return values. This allows
+			 * aio_linux_handle_io_finished() to be successfully
+			 * called from smbd/aio.c:wait_for_aio_completion()
+			 * once we return from here with all io's done.
+			 */
+			aio_linux_setup_returns(ioev);
+			return;
+		}
+	}
+
+	/* Jobid completed we weren't waiting for.
+	   We must reshedule this as an immediate event
+	   on the main event context. */
+	im = tevent_create_immediate(NULL);
+	if (!im) {
+		exit_server_cleanly("aio_linux_handle_suspend_completion: no memory");
+	}
+
+	new_ioev = (struct io_event *)talloc_memdup(NULL,
+						ioev,
+						sizeof(struct io_event));
+	if (!new_ioev) {
+		exit_server_cleanly("aio_linux_handle_suspend_completion: no memory");
+	}
+
+	DEBUG(10,("aio_linux_handle_suspend_completion: "
+			"re-scheduling requestid %d\n",
+			pd->requestid));
+
+	tevent_schedule_immediate(im,
+			server_event_context(),
+			aio_linux_handle_immediate,
+			(void *)new_ioev);
+}
+
+/************************************************************************
+ Callback when an IO completes from a suspend call.
+***********************************************************************/
+
+static void aio_linux_handle_suspend_completion(struct event_context *event_ctx,
+				struct fd_event *event,
+				uint16 flags,
+				void *p)
+{
+	struct suspend_private *sp = (struct suspend_private *)p;
+	uint64_t remaining_events = sp->num_entries - sp->num_finished;
+	uint64_t num_events = 0;
+
+	DEBUG(10, ("aio_linux_handle_suspend_completion called with flags=%d\n",
+			(int)flags));
+
+	if ((flags & EVENT_FD_READ) == 0) {
+		return;
+	}
+
+	/* Read the number of events available. */
+	if (sys_read(event_fd, &num_events, sizeof(num_events)) !=
+			sizeof(num_events)) {
+		smb_panic("aio_linux_handle_completion: invalid read");
+	}
+
+	while (num_events > 0) {
+		uint64_t events_to_read = MIN(num_events, remaining_events);
+		struct timespec ts;
+		int i;
+		int ret;
+
+		ts.tv_sec = 0;
+		ts.tv_nsec = 0;
+
+		ret = io_getevents(io_ctx,
+			1,
+			(long)events_to_read,
+			io_recv_events,
+			&ts);
+
+		if (ret < 0) {
+			errno = -ret;
+			DEBUG(1, ("aio_linux_handle_suspend_completion: "
+				"io_getevents error %s\n",
+				strerror(errno) ));
+			return;
+		}
+
+		if (ret == 0) {
+			DEBUG(10, ("aio_linux_handle_suspend_completion: "
+				"io_getevents returned 0\n"));
+			continue;
+		}
+
+		/* ret is positive. */
+		for (i = 0; i < ret; i++) {
+			aio_linux_handle_suspend_io_finished(sp,
+					&io_recv_events[i]);
+		}
+
+		num_events -= ret;
+	}
+}
+
+static void aio_linux_suspend_timed_out(struct tevent_context *event_ctx,
+					struct tevent_timer *te,
+					struct timeval now,
+					void *private_data)
+{
+	bool *timed_out = (bool *)private_data;
+	/* Remove this timed event handler. */
+	TALLOC_FREE(te);
+	*timed_out = true;
+}
+
+/************************************************************************
+ Called to request everything to stop until all IO is completed.
+***********************************************************************/
+
+static int aio_linux_suspend(struct vfs_handle_struct *handle,
+			struct files_struct *fsp,
+			const SMB_STRUCT_AIOCB * const aiocb_array[],
+			int n,
+			const struct timespec *timeout)
+{
+	struct event_context *ev = NULL;
+	struct fd_event *sock_event = NULL;
+	int ret = -1;
+	struct suspend_private sp;
+	bool timed_out = false;
+	TALLOC_CTX *frame = talloc_stackframe();
+
+	/* This is a blocking call, and has to use a sub-event loop. */
+	ev = event_context_init(frame);
+	if (ev == NULL) {
+		errno = ENOMEM;
+		goto out;
+	}
+
+	if (timeout) {
+		struct timeval tv = convert_timespec_to_timeval(*timeout);
+		struct tevent_timer *te = tevent_add_timer(ev,
+						frame,
+						timeval_current_ofs(tv.tv_sec,
+								    tv.tv_usec),
+						aio_linux_suspend_timed_out,
+						&timed_out);
+		if (!te) {
+			errno = ENOMEM;
+			goto out;
+		}
+	}
+
+	ZERO_STRUCT(sp);
+	sp.num_entries = n;
+	sp.aiocb_array = aiocb_array;
+	sp.num_finished = 0;
+
+	sock_event = tevent_add_fd(ev,
+				frame,
+				event_fd,
+				TEVENT_FD_READ,
+				aio_linux_handle_suspend_completion,
+				(void *)&sp);
+	if (sock_event == NULL) {
+		goto out;
+	}
+	/*
+	 * We're going to cheat here. We know that smbd/aio.c
+	 * only calls this when it's waiting for every single
+	 * outstanding call to finish on a close, so just wait
+	 * individually for each IO to complete. We don't care
+	 * what order they finish - only that they all do. JRA.
+	 */
+	while (sp.num_entries != sp.num_finished) {
+		if (tevent_loop_once(ev) == -1) {
+			goto out;
+		}
+
+		if (timed_out) {
+			errno = EAGAIN;
+			goto out;
+		}
+	}
+
+	ret = 0;
+
+  out:
+
+	TALLOC_FREE(frame);
+	return ret;
+}
+
+static int aio_linux_connect(vfs_handle_struct *handle, const char *service,
+			       const char *user)
+{
+	/*********************************************************************
+	 * How many io_events to initialize ?
+	 * 128 per process seems insane as a default until you realize that
+	 * (a) Throttling is done in SMB2 via the crediting algorithm.
+	 * (b) SMB1 clients are limited to max_mux (50) outstanding
+	 *     requests and Windows clients don't use this anyway.
+	 * Essentially we want this to be unlimited unless smb.conf
+	 * says different.
+	 *********************************************************************/
+	aio_pending_size = lp_parm_int(
+		SNUM(handle->conn), "aio_linux", "aio num events", 128);
+	return SMB_VFS_NEXT_CONNECT(handle, service, user);
+}
+
+static struct vfs_fn_pointers vfs_aio_linux_fns = {
+	.connect_fn = aio_linux_connect,
+	.aio_read = aio_linux_read,
+	.aio_write = aio_linux_write,
+	.aio_return_fn = aio_linux_return_fn,
+	.aio_cancel = aio_linux_cancel,
+	.aio_error_fn = aio_linux_error_fn,
+	.aio_suspend = aio_linux_suspend,
+};
+
+NTSTATUS vfs_aio_linux_init(void)
+{
+	return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
+				"aio_linux", &vfs_aio_linux_fns);
+}
-- 
1.7.7.3