[v4,2/5] blk-mq: add shallow depth option for blk_mq_get_tag()

Commit Message

Omar Sandoval April 14, 2017, 7:59 a.m. UTC

From: Omar Sandoval <[e-mail]>

Wire up the sbitmap_get_shallow() operation to the tag code so that a
caller can limit the number of tags available to it.

Signed-off-by: Omar Sandoval <[e-mail]>
---
 block/blk-mq-tag.c | 5 ++++-
 block/blk-mq.h     | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

Patch

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 9d97bfc4d465..d0be72ccb091 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -96,7 +96,10 @@  static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
 	if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&
 	    !hctx_may_queue(data->hctx, bt))
 		return -1;
-	return __sbitmap_queue_get(bt);
+	if (data->shallow_depth)
+		return __sbitmap_queue_get_shallow(bt, data->shallow_depth);
+	else
+		return __sbitmap_queue_get(bt);
 }
 
 unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 7e6f2e467696..524f44742816 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -141,6 +141,7 @@  struct blk_mq_alloc_data {
 	/* input parameter */
 	struct request_queue *q;
 	unsigned int flags;
+	unsigned int shallow_depth;
 
 	/* input & output parameter */
 	struct blk_mq_ctx *ctx;