[PATCH] fix xfs kernel so 2GiB logs work

[Michael Nishimoto <miken@agami.com>]

I hope that I've got everything now.

Ensure that 2 GiB xfs logs work properly.

We found this while experimenting with 2GiB xfs logs.
The previous code never assumed that xfs logs would
ever get so large.

Signed-off-by: Michael Nishimoto <miken@agami.com>
===========================================================
--- xfs_log.2.c 2008-04-01 11:55:45.000000000 -0700
+++ xfs_log.3.c 2008-04-01 11:56:53.000000000 -0700
@@ -230,20 +230,24 @@
  static void
  xlog_grant_add_space_write(struct log *log, int bytes)
  {
-       log->l_grant_write_bytes += bytes;
-       if (log->l_grant_write_bytes > log->l_logsize) {
-               log->l_grant_write_bytes -= log->l_logsize;
-               log->l_grant_write_cycle++;
+       int tmp = log->l_logsize - log->l_grant_write_bytes;
+       if (tmp > bytes)
+               log->l_grant_write_bytes += bytes;
+       else {
+               log->l_grant_write_cycle++;
+               log->l_grant_write_bytes = bytes - tmp;
         }
  }

  static void
  xlog_grant_add_space_reserve(struct log *log, int bytes)
  {
-       log->l_grant_reserve_bytes += bytes;
-       if (log->l_grant_reserve_bytes > log->l_logsize) {
-               log->l_grant_reserve_bytes -= log->l_logsize;
-               log->l_grant_reserve_cycle++;
+       int tmp = log->l_logsize - log->l_grant_reserve_bytes;
+       if (tmp > bytes)
+               log->l_grant_reserve_bytes += bytes;
+       else {
+               log->l_grant_reserve_cycle++;
+               log->l_grant_reserve_bytes = bytes - tmp;
         }
  }