From 3228f48be2d19b2dd90db96ec16a40187a2946f3 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 28 Oct 2013 13:33:58 -0600 Subject: blk-mq: fix for flush deadlock The flush state machine takes in a struct request, which then is submitted multiple times to the underling driver. The old block code requeses the same request for each of those, so it does not have an issue with tapping into the request pool. The new one on the other hand allocates a new request for each of the actualy steps of the flush sequence. If have already allocated all of the tags for IO, we will fail allocating the flush request. Set aside a reserved request just for flushes. Signed-off-by: Jens Axboe --- block/blk-flush.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block/blk-flush.c') diff --git a/block/blk-flush.c b/block/blk-flush.c index 3e4cc9c7890a..331e627301ea 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -286,7 +286,7 @@ static void mq_flush_work(struct work_struct *work) /* We don't need set REQ_FLUSH_SEQ, it's for consistency */ rq = blk_mq_alloc_request(q, WRITE_FLUSH|REQ_FLUSH_SEQ, - __GFP_WAIT|GFP_ATOMIC); + __GFP_WAIT|GFP_ATOMIC, true); rq->cmd_type = REQ_TYPE_FS; rq->end_io = flush_end_io; -- cgit v1.2.3-59-g8ed1b