MFP4 (with some minor changes):

Implement the linux_io_* syscalls (AIO). They are only enabled if the native
AIO code is available (either compiled in to the kernel or as a module) at
the time the functions are used. If the AIO stuff is not available there
will be a ENOSYS.

From the submitter:
---snip---
DESIGN NOTES:

1. Linux permits a process to own multiple AIO queues (distinguished by
   "context"), but FreeBSD creates only one single AIO queue per process.
   My code maintains a request queue (STAILQ of queue(3)) per "context",
   and throws all AIO requests of all contexts owned by a process into
   the single FreeBSD per-process AIO queue.

   When the process calls io_destroy(2), io_getevents(2), io_submit(2) and
   io_cancel(2), my code can pick out requests owned by the specified context
   from the single FreeBSD per-process AIO queue according to the per-context
   request queues maintained by my code.

2. The request queue maintained by my code stores contrast information between
   Linux IO control blocks (struct linux_iocb) and FreeBSD IO control blocks
   (struct aiocb). FreeBSD IO control block actually exists in userland memory
   space, required by FreeBSD native aio_XXXXXX(2).

3. It is quite troubling that the function io_getevents() of libaio-0.3.105
   needs to use Linux-specific "struct aio_ring", which is a partial mirror
   of context in user space. I would rather take the address of context in
   kernel as the context ID, but the io_getevents() of libaio forces me to
   take the address of the "ring" in user space as the context ID.

   To my surprise, one comment line in the file "io_getevents.c" of
   libaio-0.3.105 reads:

             Ben will hate me for this

REFERENCE:

1. Linux kernel source code:   http://www.kernel.org/pub/linux/kernel/v2.6/
   (include/linux/aio_abi.h, fs/aio.c)

2. Linux manual pages:         http://www.kernel.org/pub/linux/docs/manpages/
   (io_setup(2), io_destroy(2), io_getevents(2), io_submit(2), io_cancel(2))

3. Linux Scalability Effort:   http://lse.sourceforge.net/io/aio.html
   The design notes:           http://lse.sourceforge.net/io/aionotes.txt

4. The package libaio, both source and binary:
       http://rpmfind.net/linux/rpm2html/search.php?query=libaio
   Simple transparent interface to Linux AIO system calls.

5. Libaio-oracle:              http://oss.oracle.com/projects/libaio-oracle/
   POSIX AIO implementation based on Linux AIO system calls (depending on
   libaio).
---snip---

Submitted by:	Li, Xiao <intron@intron.ac>

2 files changed, 7 insertions, 5 deletions

diff --git a/sys/i386/linux/linux.h b/sys/i386/linux/linux.h
index 9ad9353..1ca7381 100644
--- a/sys/i386/linux/linux.h
+++ b/sys/i386/linux/linux.h
@@ -803,4 +803,6 @@ typedef int l_mqd_t;
 
 #define THREADING_FLAGS (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND)
 
+#include <compat/linux/linux_aio.h>
+
 #endif /* !_I386_LINUX_LINUX_H_ */
diff --git a/sys/i386/linux/syscalls.master b/sys/i386/linux/syscalls.master
index 61ba1d2..6b00584 100644
--- a/sys/i386/linux/syscalls.master
+++ b/sys/i386/linux/syscalls.master
@@ -409,11 +409,11 @@
 242	AUE_NULL	UNIMPL	linux_sched_getaffinity
 243	AUE_NULL	STD	{ int linux_set_thread_area(struct l_user_desc *desc); }
 244	AUE_NULL	STD	{ int linux_get_thread_area(struct l_user_desc *desc); }
-245	AUE_NULL	UNIMPL	linux_io_setup
-246	AUE_NULL	UNIMPL	linux_io_destroy
-247	AUE_NULL	UNIMPL	linux_io_getevents
-248	AUE_NULL	UNIMPL	linux_io_submit
-249	AUE_NULL	UNIMPL	linux_io_cancel
+245	AUE_NULL	STD	{ int linux_io_setup(l_uint nr_reqs, linux_aio_context_t *ctxp); }
+246	AUE_NULL	STD	{ int linux_io_destroy(linux_aio_context_t ctx); }
+247	AUE_NULL	STD	{ int linux_io_getevents(linux_aio_context_t ctx_id, l_long min_nr, l_long nr, struct linux_io_event *events, struct l_timespec *timeout); }
+248	AUE_NULL	STD	{ int linux_io_submit(linux_aio_context_t ctx_id, l_long nr, struct linux_iocb **iocbpp); }
+249	AUE_NULL	STD	{ int linux_io_cancel(linux_aio_context_t ctx_id, struct linux_iocb *iocb, struct linux_io_event *result); }
 250	AUE_NULL	STD	{ int linux_fadvise64(void); }
 251	AUE_NULL	UNIMPL
 252	AUE_EXIT	STD	{ int linux_exit_group(int error_code); }