Since the srcu structure is rather large (184 bytes on an x86-64
system), only allocate it if needed.
Reported-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Omar Sandoval <osandov@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/blk-mq.c | 16 +++++++++++++++-
include/linux/blk-mq.h | 5 +++--
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bc96e6007e53..b8092786d42f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2227,6 +2227,20 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
}
EXPORT_SYMBOL(blk_mq_init_queue);
+static int blk_mq_hw_ctx_size(struct request_queue *q)
+{
+ int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
+
+ BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, queue_rq_srcu),
+ __alignof__(struct blk_mq_hw_ctx)) !=
+ sizeof(struct blk_mq_hw_ctx));
+
+ if (tag_set->flags & BLK_MQ_F_BLOCKING)
+ hw_ctx_size += sizeof(struct srcu_struct);
+
+ return hw_ctx_size;
+}
+
static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct request_queue *q)
{
@@ -2241,7 +2255,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
continue;
node = blk_mq_hw_queue_to_node(q->mq_map, i);
- hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
+ hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(q),
GFP_KERNEL, node);
if (!hctxs[i])
break;
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index c63d1d98404a..c589b81be491 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -39,8 +39,6 @@ struct blk_mq_hw_ctx {
struct blk_mq_tags *tags;
struct blk_mq_tags *sched_tags;
- struct srcu_struct queue_rq_srcu[1];
-
unsigned long queued;
unsigned long run;
#define BLK_MQ_MAX_DISPATCH_ORDER 7
@@ -62,6 +60,9 @@ struct blk_mq_hw_ctx {
struct dentry *debugfs_dir;
struct dentry *sched_debugfs_dir;
#endif
+
+ /* Must be the last member - see also blk_mq_hw_ctx_size(). */
+ struct srcu_struct queue_rq_srcu[0];
};
struct blk_mq_tag_set {
--
2.12.2
