[XFS] Sanitise xfs_log_force error checking.

xfs_log_force() is declared to return an error, but we almost never check
it. We don't need to check it in most cases; if there's a log I/O error
then we'll be shutting down the filesystem anyway and that means we'll
catch the error somewhere else.

However, on certain calls we should be returning an error - sync
transactions, fsync, sync writes, etc. so this isn't a pure black and
white distinction. Hence make xfs_log_force() a void function that issues
a warning to the syslog on error, and call _xfs_log_force() in all the
places where we actually care about the error status returned.

SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30832a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h
index 4cdac04..d1d678e 100644
--- a/fs/xfs/xfs_log.h
+++ b/fs/xfs/xfs_log.h
@@ -142,8 +142,9 @@
 			 xfs_lsn_t	lsn,
 			 uint		flags,
 			 int		*log_forced);
-#define xfs_log_force(mp, lsn, flags) \
-	_xfs_log_force(mp, lsn, flags, NULL);
+void	  xfs_log_force(struct xfs_mount	*mp,
+			xfs_lsn_t		lsn,
+			uint			flags);
 int	  xfs_log_mount(struct xfs_mount	*mp,
 			struct xfs_buftarg	*log_target,
 			xfs_daddr_t		start_block,