[PATCH 4/5] blk-mq-debugfs: Show busy requests

Bart Van Assche
2017-05-25T23:38:09Z

Requests that got stuck in a block driver are neither on
blk_mq_ctx.rq_list nor on any hw dispatch queue. Make these
visible in debugfs through the "busy" attribute.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-debugfs.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 8b06a12c1461..70a2b955afee 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -370,6 +370,30 @@ static const struct seq_operations hctx_dispatch_seq_ops = {
.show = blk_mq_debugfs_rq_show,
};

+struct show_busy_ctx {
+ struct seq_file *m;
+ struct blk_mq_hw_ctx *hctx;
+};
+
+static void hctx_show_busy(struct request *rq, void *data, bool reserved)
+{
+ const struct show_busy_ctx *ctx = data;
+
+ if (blk_mq_map_queue(rq->q, rq->mq_ctx->cpu) == ctx->hctx &&
+ test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
+ blk_mq_debugfs_rq_show(ctx->m, &rq->queuelist);
+}
+
+static int hctx_busy_show(void *data, struct seq_file *m)
+{
+ struct blk_mq_hw_ctx *hctx = data;
+ struct show_busy_ctx ctx = { .m = m, .hctx = hctx };
+
+ blk_mq_tagset_busy_iter(hctx->queue->tag_set, hctx_show_busy, &ctx);
+
+ return 0;
+}
+
static int hctx_ctx_map_show(void *data, struct seq_file *m)
{
struct blk_mq_hw_ctx *hctx = data;
@@ -705,6 +729,7 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
{"state", 0400, hctx_state_show},
{"flags", 0400, hctx_flags_show},
{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},
+ {"busy", 0400, hctx_busy_show},
{"ctx_map", 0400, hctx_ctx_map_show},
{"tags", 0400, hctx_tags_show},
{"tags_bitmap", 0400, hctx_tags_bitmap_show},
--
2.12.2