[PATCH 0/4] blk-mq ->queue_rq error return fixes

[PATCH 0/4] blk-mq ->queue_rq error return fixes

[Christoph Hellwig]

[PATCH 1/4] blk-mq: support at_head inserations for blk_execute_rq

[Christoph Hellwig]

[-- Attachment #1: 0001-blk-mq-support-at_head-inserations-for-blk_execute_r.patch --]
[-- Type: text/plain, Size: 3495 bytes --]

This is neede for proper SG_IO operation as well as various uses of
blk_execute_rq from the SCSI midlayer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-exec.c       |    2 +-
 block/blk-mq.c         |   17 ++++++++++-------
 include/linux/blk-mq.h |    3 ++-
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/block/blk-exec.c b/block/blk-exec.c
index bbfc072..c68613b 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -65,7 +65,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 	 * be resued after dying flag is set
 	 */
 	if (q->mq_ops) {
-		blk_mq_insert_request(q, rq, true);
+		blk_mq_insert_request(q, rq, at_head, true);
 		return;
 	}
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 57039fc..40fc4dd 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -693,13 +693,16 @@ static void blk_mq_work_fn(struct work_struct *work)
 }
 
 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
-				    struct request *rq)
+				    struct request *rq, bool at_head)
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 
 	trace_block_rq_insert(hctx->queue, rq);
 
-	list_add_tail(&rq->queuelist, &ctx->rq_list);
+	if (at_head)
+		list_add(&rq->queuelist, &ctx->rq_list);
+	else
+		list_add_tail(&rq->queuelist, &ctx->rq_list);
 	blk_mq_hctx_mark_pending(hctx, ctx);
 
 	/*
@@ -709,7 +712,7 @@ static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
 }
 
 void blk_mq_insert_request(struct request_queue *q, struct request *rq,
-			   bool run_queue)
+			   bool at_head, bool run_queue)
 {
 	struct blk_mq_hw_ctx *hctx;
 	struct blk_mq_ctx *ctx, *current_ctx;
@@ -728,7 +731,7 @@ void blk_mq_insert_request(struct request_queue *q, struct request *rq,
 			rq->mq_ctx = ctx;
 		}
 		spin_lock(&ctx->lock);
-		__blk_mq_insert_request(hctx, rq);
+		__blk_mq_insert_request(hctx, rq, at_head);
 		spin_unlock(&ctx->lock);
 
 		blk_mq_put_ctx(current_ctx);
@@ -760,7 +763,7 @@ void blk_mq_run_request(struct request *rq, bool run_queue, bool async)
 
 	/* ctx->cpu might be offline */
 	spin_lock(&ctx->lock);
-	__blk_mq_insert_request(hctx, rq);
+	__blk_mq_insert_request(hctx, rq, false);
 	spin_unlock(&ctx->lock);
 
 	blk_mq_put_ctx(current_ctx);
@@ -798,7 +801,7 @@ static void blk_mq_insert_requests(struct request_queue *q,
 		rq = list_first_entry(list, struct request, queuelist);
 		list_del_init(&rq->queuelist);
 		rq->mq_ctx = ctx;
-		__blk_mq_insert_request(hctx, rq);
+		__blk_mq_insert_request(hctx, rq, false);
 	}
 	spin_unlock(&ctx->lock);
 
@@ -950,7 +953,7 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		__blk_mq_free_request(hctx, ctx, rq);
 	else {
 		blk_mq_bio_to_request(rq, bio);
-		__blk_mq_insert_request(hctx, rq);
+		__blk_mq_insert_request(hctx, rq, false);
 	}
 
 	spin_unlock(&ctx->lock);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 161b231..8e6e710 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -119,7 +119,8 @@ void blk_mq_init_commands(struct request_queue *, void (*init)(void *data, struc
 
 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule);
 
-void blk_mq_insert_request(struct request_queue *, struct request *, bool);
+void blk_mq_insert_request(struct request_queue *, struct request *,
+		bool, bool);
 void blk_mq_run_queues(struct request_queue *q, bool async);
 void blk_mq_free_request(struct request *rq);
 bool blk_mq_can_queue(struct blk_mq_hw_ctx *);
-- 
1.7.10.4

[PATCH 2/4] blk-mq: divert __blk_put_request for MQ ops

[Christoph Hellwig]

[-- Attachment #1: 0002-blk-mq-divert-__blk_put_request-for-MQ-ops.patch --]
[-- Type: text/plain, Size: 673 bytes --]

__blk_put_request needs to call into the blk-mq code just like
blk_put_request.  As we don't have the queue lock in this case both
end up calling the same function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index c00e0bd..06636f3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1278,6 +1278,11 @@ void __blk_put_request(struct request_queue *q, struct request *req)
 	if (unlikely(!q))
 		return;
 
+	if (q->mq_ops) {
+		blk_mq_free_request(req);
+		return;
+	}
+
 	blk_pm_put_request(req);
 
 	elv_completed_request(q, req);
-- 
1.7.10.4

[PATCH 3/4] blk-mq: handle dma_drain_size

[Christoph Hellwig]

[-- Attachment #1: 0003-blk-mq-handle-dma_drain_size.patch --]
[-- Type: text/plain, Size: 876 bytes --]

Make blk-mq handle the dma_drain_size field the same way as the old request
path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-mq.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 40fc4dd..35800e1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -561,6 +561,16 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 		list_del_init(&rq->queuelist);
 		blk_mq_start_request(rq);
 
+		if (q->dma_drain_size && blk_rq_bytes(rq)) {
+			/*
+			 * make sure space for the drain appears we
+			 * know we can do this because max_hw_segments
+			 * has been adjusted to be one fewer than the
+			 * device can handle
+			 */
+			rq->nr_phys_segments++;
+		}
+
 		/*
 		 * Last request in the series. Flag it as such, this
 		 * enables drivers to know when IO should be kicked off,
-- 
1.7.10.4

[PATCH 4/4] blk-mq: initialize sg_reserved_size

[Christoph Hellwig]

[-- Attachment #1: 0004-blk-mq-initialize-sg_reserved_size.patch --]
[-- Type: text/plain, Size: 599 bytes --]

To behave the same way as the old request path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-mq.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 35800e1..f5fcd9a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1373,6 +1373,8 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
 	q->mq_ops = reg->ops;
 	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
+	q->sg_reserved_size = INT_MAX;
+
 	blk_queue_make_request(q, blk_mq_make_request);
 	blk_queue_rq_timed_out(q, reg->ops->timeout);
 	if (reg->timeout)
-- 
1.7.10.4

Re: [PATCH 0/4] blk-mq ->queue_rq error return fixes

[Christoph Hellwig]

sorry, this was a resend of an older series, ignore it.