blk-mq: export software queue pending map to debugfs

This is useful for debugging problems where we've gotten stuck with
requests in the software queues.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index ee947f2f605b7ae90c8fda647de3c2b4419a7a0c..857bdadc6b1f367e36e4634c0709dae18392d1ba 100644 (file)
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -134,6 +134,26 @@ static const struct file_operations hctx_dispatch_fops = {
        .release        = seq_release,
 };
 
+static int hctx_ctx_map_show(struct seq_file *m, void *v)
+{
+       struct blk_mq_hw_ctx *hctx = m->private;
+
+       sbitmap_bitmap_show(&hctx->ctx_map, m);
+       return 0;
+}
+
+static int hctx_ctx_map_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, hctx_ctx_map_show, inode->i_private);
+}
+
+static const struct file_operations hctx_ctx_map_fops = {
+       .open           = hctx_ctx_map_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+
 static void *ctx_rq_list_start(struct seq_file *m, loff_t *pos)
 {
        struct blk_mq_ctx *ctx = m->private;
@@ -179,6 +199,7 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
        {"state", 0400, &hctx_state_fops},
        {"flags", 0400, &hctx_flags_fops},
        {"dispatch", 0400, &hctx_dispatch_fops},
+       {"ctx_map", 0400, &hctx_ctx_map_fops},
 };
 
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {