[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>

fs/xfs/xfs_log.c

@@ -382,7 +382,27 @@ _xfs_log_force(
 		return xlog_state_sync_all(log, flags, log_flushed);
 	else
 		return xlog_state_sync(log, lsn, flags, log_flushed);
-}	/* xfs_log_force */
+}	/* _xfs_log_force */
+
+/*
+ * Wrapper for _xfs_log_force(), to be used when caller doesn't care
+ * about errors or whether the log was flushed or not. This is the normal
+ * interface to use when trying to unpin items or move the log forward.
+ */
+void
+xfs_log_force(
+	xfs_mount_t	*mp,
+	xfs_lsn_t	lsn,
+	uint		flags)
+{
+	int	error;
+	error = _xfs_log_force(mp, lsn, flags, NULL);
+	if (error) {
+		xfs_fs_cmn_err(CE_WARN, mp, "xfs_log_force: "
+			"error %d returned.", error);
+	}
+}
+
 
 /*
  * Attaches a new iclog I/O completion callback routine during
@@ -634,7 +654,8 @@ xfs_log_unmount_write(xfs_mount_t *mp)
 	if (mp->m_flags & XFS_MOUNT_RDONLY)
 		return 0;
 
-	xfs_log_force(mp, 0, XFS_LOG_FORCE|XFS_LOG_SYNC);
+	error = _xfs_log_force(mp, 0, XFS_LOG_FORCE|XFS_LOG_SYNC, NULL);
+	ASSERT(error || !(XLOG_FORCED_SHUTDOWN(log)));
 
 #ifdef DEBUG
 	first_iclog = iclog = log->l_iclog;

fs/xfs/xfs_log.h

@@ -142,8 +142,9 @@ int	  _xfs_log_force(struct xfs_mount *mp,
 			 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,

fs/xfs/xfs_rw.c

@@ -126,11 +126,11 @@ xfs_write_sync_logforce(
 		 * when we return.
 		 */
 		if (iip && iip->ili_last_lsn) {
-			xfs_log_force(mp, iip->ili_last_lsn,
-					XFS_LOG_FORCE | XFS_LOG_SYNC);
+			error = _xfs_log_force(mp, iip->ili_last_lsn,
+					XFS_LOG_FORCE | XFS_LOG_SYNC, NULL);
 		} else if (xfs_ipincount(ip) > 0) {
-			xfs_log_force(mp, (xfs_lsn_t)0,
-					XFS_LOG_FORCE | XFS_LOG_SYNC);
+			error = _xfs_log_force(mp, (xfs_lsn_t)0,
+					XFS_LOG_FORCE | XFS_LOG_SYNC, NULL);
 		}
 
 	} else {