GFS2: Fix bug trap and journaled data fsync

Journaled data requires that a complete flush of all dirty data for
the file is done, in order that the ail flush which comes after
will succeed.

Also the recently enhanced bug trap can trigger falsely in case
an ail flush from fsync races with a page read. This updates the
bug trap such that it will ignore buffers which are locked and
only trigger on dirty and/or pinned buffers when the ail flush
is run from fsync. The original bug trap is retained when ail
flush is run from ->go_sync()

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/file.c

@@ -590,6 +590,8 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
 			mutex_unlock(&inode->i_mutex);
 			return ret;
 		}
+		if (gfs2_is_jdata(ip))
+			filemap_write_and_wait(mapping);
 		gfs2_ail_flush(ip->i_gl);
 		mutex_unlock(&inode->i_mutex);
 	}

fs/gfs2/glops.c

@@ -46,7 +46,7 @@ static void gfs2_ail_error(struct gfs2_glock *gl, const struct buffer_head *bh)
  * None of the buffers should be dirty, locked, or pinned.
  */
 
-static void __gfs2_ail_flush(struct gfs2_glock *gl)
+static void __gfs2_ail_flush(struct gfs2_glock *gl, unsigned long b_state)
 {
 	struct gfs2_sbd *sdp = gl->gl_sbd;
 	struct list_head *head = &gl->gl_ail_list;
@@ -60,7 +60,7 @@ static void __gfs2_ail_flush(struct gfs2_glock *gl)
 				bd_ail_gl_list);
 		bh = bd->bd_bh;
 		blocknr = bh->b_blocknr;
-		if (buffer_busy(bh))
+		if (bh->b_state & b_state)
 			gfs2_ail_error(gl, bh);
 		bh->b_private = NULL;
 		gfs2_remove_from_ail(bd); /* drops ref on bh */
@@ -99,7 +99,7 @@ static void gfs2_ail_empty_gl(struct gfs2_glock *gl)
 	BUG_ON(current->journal_info);
 	current->journal_info = &tr;
 
-	__gfs2_ail_flush(gl);
+	__gfs2_ail_flush(gl, (1ul << BH_Dirty)|(1ul << BH_Pinned)|(1ul << BH_Lock));
 
 	gfs2_trans_end(sdp);
 	gfs2_log_flush(sdp, NULL);
@@ -117,7 +117,7 @@ void gfs2_ail_flush(struct gfs2_glock *gl)
 	ret = gfs2_trans_begin(sdp, 0, revokes);
 	if (ret)
 		return;
-	__gfs2_ail_flush(gl);
+	__gfs2_ail_flush(gl, (1ul << BH_Dirty)|(1ul << BH_Pinned));
 	gfs2_trans_end(sdp);
 	gfs2_log_flush(sdp, NULL);
 }