[PATCH 1/2] change io_cancel return code for no cancel case

[Benjamin LaHaise]

From: Wendy Cheng <wcheng@xxxxxxxxxx>

Note that other than few exceptions, most of the current filesystem and/or
drivers do not have aio cancel specifically defined (kiob->ki_cancel field
is mostly NULL).  However, sys_io_cancel system call universally sets
return code to -EAGAIN.  This gives applications a wrong impression that
this call is implemented but just never works.  We have customer inquires
about this issue.

Changed by Benjamin LaHaise to EINVAL instead of ENOSYS

Signed-off-by: S. Wendy Cheng <wcheng@xxxxxxxxxx>
Acked-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>

 aio.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -purN --exclude=description 00_linus-git/fs/aio.c 01_aio_enosys/fs/aio.c
--- 00_linus-git/fs/aio.c	2005-09-07 10:59:31.000000000 -0400
+++ 01_aio_enosys/fs/aio.c	2005-09-07 11:03:55.000000000 -0400
@@ -1673,7 +1673,7 @@ asmlinkage long sys_io_cancel(aio_contex
 				ret = -EFAULT;
 		}
 	} else
-		printk(KERN_DEBUG "iocb has no cancel operation\n");
+		ret = -EINVAL;
 
 	put_ioctx(ctx);
 
-
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