block: fix bug with inserting flush requests as sort/merge

With the introduction of the on-stack plugging, we would assume that any request being inserted was a normal file system request. As flush/fua requires a special insert mode, this caused problems. Fix this up by checking for this in flush_plug_list() and use the appropriate insert mechanism. Big thanks goes to Markus Tripplesdorf for tirelessly testing patches, and to Sergey Senozhatsky for helping find the real issue. Reported-by: Markus Tripplesdorf <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
liveeasily · Mar 25, 2011 · 401a18e · 401a18e
1 parent 6c51038
commit 401a18e
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/block/blk-core.c b/block/blk-core.c
@@ -2702,7 +2702,10 @@ static void flush_plug_list(struct blk_plug *plug)
 		/*
 		 * rq is already accounted, so use raw insert
 		 */
-		__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
+		if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
+			__elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
+		else
+			__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
 	}
 
 	if (q) {