[PATCH v2 7/8] xfs: Add xfs_log_rlimit.[c|h]

[Michael L. Semon]

On 05/17/2013 01:39 AM, Jeff Liu wrote:
> From: Jie Liu <jeff.liu at oracle.com>
>
> Add source files for xfs_log_rlimit.[c|h].
> The new source would be used for the log space validation.

Update:  To build the kernel, I'm getting by on a sysadmin hack that 
looks like this:

--- linux/fs/xfs/xfs_log_rlimit.c.orig	2013-05-17 03:36:28.983493357 -0400
+++ linux/fs/xfs/xfs_log_rlimit.c	2013-05-17 04:21:07.090661828 -0400
@@ -127,8 +127,10 @@
  	 * Also, the log size should be a multiple of the log stripe unit, round
  	 * it up to lsunit boundary if lsunit is specified.
  	 */
-	minlblks = lsunit ? (roundup(BTOBB(maxlres), lsunit) + 2 * lsunit) * 2 :
-			    BTOBB(maxlres) * 2;
+	minlblks = lsunit ?
+		(roundup((const int)(BTOBB(maxlres)), lsunit) +
+		2 * lsunit) * 2 :
+			BTOBB(maxlres) * 2;

  	if (log->l_logBBsize < minlblks) {
  		xfs_crit(mp,

However, that makes no sense.  There is a roundup in <linux/kernel.h> 
that goes like this:

/* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
#define roundup(x, y) (                                 \
{                                                       \
         const typeof(y) __y = y;                        \
         (((x) + (__y - 1)) / __y) * __y;                \
}                                                       \
)

Okay, so that gave me the inspiration to cast the type so gcc-4.8.0 
wouldn't call __divdi3.  But why did this make a difference?

Disclaimer:  I'm not a C macro guru, so I don't know which random 
sequence of punctuation keys would make roundup() happy.

Michael