[PATCH -mm 1/5][AIO] - Rework compat_sys_io_submit

["Sébastien Dugué" <sebastien.dugue@bull.net>]

                 compat_sys_io_submit() cleanup


  Cleanup compat_sys_io_submit by duplicating some of the native syscall
logic in the compat layer and directly calling io_submit_one() instead
of fooling the syscall into thinking it is called from a native 64-bit
caller.

  This is needed for the completion notification patch to avoid having
to rewrite each iocb on the caller stack for sys_io_submit() to find the
sigevents.



 compat.c |   61 +++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 35 insertions(+), 26 deletions(-)

Signed-off-by: Sébastien Dugué <sebastien.dugue@bull.net>

Index: linux-2.6.19-rc6-mm2/fs/compat.c
===================================================================
--- linux-2.6.19-rc6-mm2.orig/fs/compat.c	2006-11-28 12:49:40.000000000
+0100 +++ linux-2.6.19-rc6-mm2/fs/compat.c	2006-11-28 12:51:35.000000000
+0100 @@ -642,40 +642,49 @@ out:
 	return ret;
 }
 
-static inline long
-copy_iocb(long nr, u32 __user *ptr32, struct iocb __user * __user *ptr64)
+asmlinkage long
+compat_sys_io_submit(aio_context_t ctx_id, int nr, u32 __user *iocb)
 {
-	compat_uptr_t uptr;
+	struct kioctx *ctx;
+	long ret = 0;
 	int i;
 
-	for (i = 0; i < nr; ++i) {
-		if (get_user(uptr, ptr32 + i))
-			return -EFAULT;
-		if (put_user(compat_ptr(uptr), ptr64 + i))
-			return -EFAULT;
-	}
-	return 0;
-}
+	if (unlikely(nr < 0))
+		return -EINVAL;
 
-#define MAX_AIO_SUBMITS 	(PAGE_SIZE/sizeof(struct iocb *))
+	if (unlikely(!access_ok(VERIFY_READ, iocb, (nr * sizeof(u32)))))
+		return -EFAULT;
 
-asmlinkage long
-compat_sys_io_submit(aio_context_t ctx_id, int nr, u32 __user *iocb)
-{
-	struct iocb __user * __user *iocb64; 
-	long ret;
+	ctx = lookup_ioctx(ctx_id);
 
-	if (unlikely(nr < 0))
+	if (unlikely(!ctx))
 		return -EINVAL;
+	for (i=0; i<nr; i++) {
+		compat_uptr_t uptr;
+		struct iocb __user *user_iocb;
+		struct iocb tmp;
 
-	if (nr > MAX_AIO_SUBMITS)
-		nr = MAX_AIO_SUBMITS;
-	
-	iocb64 = compat_alloc_user_space(nr * sizeof(*iocb64));
-	ret = copy_iocb(nr, iocb, iocb64);
-	if (!ret)
-		ret = sys_io_submit(ctx_id, nr, iocb64);
-	return ret;
+		if (get_user(uptr, iocb + i)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		user_iocb = compat_ptr(uptr);
+
+		if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		ret = io_submit_one(ctx, user_iocb, &tmp);
+
+		if (ret)
+			break;
+	}
+
+	put_ioctx(ctx);
+
+	return i? i: ret;
 }
 
 struct compat_ncp_mount_data {