[Ocfs2-devel] [PATCH 1/1] Ocfs2: Add new OCFS2_IOC_INFO ioctl for ocfs2 v7.

[Joel Becker]

On Wed, May 19, 2010 at 10:28:55AM +0800, Tristan Ye wrote:
> The reason why we need this ioctl is to offer the none-privileged
> end-user a possibility to get filesys info gathering.
> 
> We use OCFS2_IOC_INFO to manipulate the new ioctl, userspace passes a
> structure to kernel containing an array of request pointers and request
> count, such as,

	This patch fails to build in ia32.  Have you tested it there?
Details below.

> diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
> index 7d9d9c1..06b6f1c 100644
> --- a/fs/ocfs2/ioctl.c
> +++ b/fs/ocfs2/ioctl.c
> @@ -23,8 +23,33 @@
>  #include "ioctl.h"
>  #include "resize.h"
>  #include "refcounttree.h"
> +#include "sysfile.h"
> +#include "buffer_head_io.h"
> +#include "suballoc.h"
> +
>  
>  #include <linux/ext2_fs.h>
> +#include <linux/compat.h>

	First off, linux/compat.h is already included as the third
include of ioctl.c.  Why are you including it again?

> +int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
> +		      int compat_flag)
> +{
> +	int i, status = 0;
> +	u64 req_addr;
> +	struct ocfs2_info_request __user *reqp;
> +
> +	if ((info->oi_count > OCFS2_INFO_MAX_REQUEST) ||
> +	    (!info->oi_requests)) {
> +		status = -EINVAL;
> +		goto bail;
> +	}
> +
> +	for (i = 0; i < info->oi_count; i++) {
> +		status = -EFAULT;
> +		if (compat_flag) {
> +			if (get_user(req_addr,
> +			     (u64 __user *)compat_ptr(info->oi_requests) + i))
> +				goto bail;

	The specific compile errors I am getting are:

/build/jlbec/linux-2.6/working/fs/ocfs2/ioctl.c: In function ‘ocfs2_info_handle’:
/build/jlbec/linux-2.6/working/fs/ocfs2/ioctl.c:414: error: implicit declaration of function ‘compat_ptr’

and:

> +		} else {
> +			if (get_user(req_addr,
> +				     (u64 __user *)(info->oi_requests) + i))
> +				goto bail;

/build/jlbec/linux-2.6/working/fs/ocfs2/ioctl.c:418: warning: cast to pointer from integer of different size

	The reason you are getting "implicit declaration of function
'compat_ptr' is because it only exists when CONFIG_COMPAT is defined.
CONFIG_COMPAT cannot exist on ia32 or any other 32-bit platform.
	I say you should define a function "ocfs2_get_request_ptr()"
that wraps both the comapt and non-compat get_user() calls.  Inside that
function, you should have:

	if (compat_flag) {
#ifdef CONFIG_COMPAT
		if (get_user(...compat_ptr...))
			goto bail;
#else
		BUG();
#endif
	} else {

	That way the info_handle() function isn't polluted by the ifdef.

Joel
-- 

Life's Little Instruction Book #109

	"Know how to drive a stick shift."

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127