+		else
+			goto out;
+		break;
+	case BLK_DBG_DIR_BSG:
+		if (dst)
+			dir_dst = kasprintf(GFP_KERNEL, "bsg/%s", dst);
+		else
+			goto out;
+		break;
+	}
+
+	/*
+	 * The base block debugfs directory is always used for the symlinks,
+	 * their target is what changes.
+	 */
+	dentry = debugfs_create_symlink(src, blk_debugfs_root, dir_dst);
+	kfree(dir_dst);
+out:
+	return dentry;
+}
+
+/**
+ * blk_queue_debugfs_symlink - symlink to the real block device debugfs_dir
+ * @q: the request queue where we know the debugfs_dir exists or will exist
+ *     eventually. Cannot be NULL.
+ * @src: name of the exposed device we wish to associate to the block device
+ * @dst: the name of the directory to which we want to symlink to, may be NULL
+ *	 if you do not know what this may be, but only if your base block device
+ *	 is not bsg. If you set this to NULL, we will have no other option but
+ *	 to look at the request_queue to infer the name, but you must ensure
+ *	 it is already be set, be mindful of asynchronous probes.
+ *
+ * Some devices don't have a request_queue of their own, however, they have an
+ * association to one and have historically supported using the same
+ * debugfs_dir which has been used to represent the whole disk for blktrace
+ * functionality. Such is the case for partitions and for scsi-generic devices.
+ * They share the same request_queue and debugfs_dir as with the whole disk for
+ * blktrace purposes.  This helper allows such association to be made explicit
+ * and enable blktrace functionality for them. scsi-generic devices representing
+ * scsi device such as block, cdrom, tape, media changer register their own
+ * debug_dir already and share the same request_queue as with scsi-generic, as
+ * such the respective scsi-generic debugfs_dir is just a symlink to these
+ * driver's debugfs_dir.
+ *
+ * To remove use debugfs_remove() on the symlink dentry returned by this
+ * function. The block layer will not clean this up for you, you must remove
+ * it yourself in case of device removal.
+ */
+struct dentry *blk_queue_debugfs_symlink(struct request_queue *q,
+					 const char *src,
+					 const char *dst)
+{
+	return queue_debugfs_symlink_type(q, src, dst, BLK_DBG_DIR_BASE);
+}
+EXPORT_SYMBOL_GPL(blk_queue_debugfs_symlink);
+
+#ifdef CONFIG_BLK_DEV_BSG
+
+void blk_debugfs_register_bsg(void)
+{
+	blk_debugfs_bsg = debugfs_create_dir("bsg", blk_debugfs_root);
+}
+
+/**
+ * blk_queue_debugfs_register_bsg - create the debugfs_dir for bsg block devices
+ * @q: the associated request_queue of the block device
+ * @name: the name of the block device exposed
+ *
+ * This is used to create the debugfs_dir used by the Block layer SCSI generic
+ * (bsg) driver. This is to be used only by the scsi-generic driver on behalf
+ * of scsi devices which work as scsi controllers or transports.
+ *
+ * This directory is cleaned up for all drivers automatically on
+ * blk_release_queue() once the request_queue reference count reaches 0.
+ */
+void blk_queue_debugfs_register_bsg(struct request_queue *q, const char *name)
+{
+	queue_debugfs_register_type(q, name, BLK_DBG_DIR_BSG);
+}
+EXPORT_SYMBOL_GPL(blk_queue_debugfs_register_bsg);
+
+/**
+ * blk_queue_debugfs_symlink_bsg - symlink to the bsg debugfs_dir
+ * @q: the request queue where we know the debugfs_dir exists or will exist
+ *     eventually. Cannot be NULL.
+ * @src: name of the scsi-generic device we wish to associate to the bsg
+ * 	request_queue.
+ * @dst: the name of the bsg request_queue debugfs_dir to which we want to
+ *	 symlink to. This cannot be NULL.
+ *
+ * This is used by scsi-generic devices representing raid controllers /
+ * transport drivers.
+ */
+struct dentry *blk_queue_debugfs_bsg_symlink(struct request_queue *q,
+					     const char *src,
+					     const char *dst)
+{
+	return queue_debugfs_symlink_type(q, src, dst, BLK_DBG_DIR_BSG);
+}
+EXPORT_SYMBOL_GPL(blk_queue_debugfs_bsg_symlink);
+#endif /* CONFIG_BLK_DEV_BSG */

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 96b7a35c898a..08edc3a54114 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c

@@ -822,9 +822,6 @@ void blk_mq_debugfs_register(struct request_queue *q)
 	struct blk_mq_hw_ctx *hctx;
 	int i;
 
-	q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent),
-					    blk_debugfs_root);
-
 	debugfs_create_files(q->debugfs_dir, q, blk_mq_debugfs_queue_attrs);
 
 	/*

@@ -855,9 +852,7 @@ void blk_mq_debugfs_register(struct request_queue *q)
 
 void blk_mq_debugfs_unregister(struct request_queue *q)
 {
-	debugfs_remove_recursive(q->debugfs_dir);
 	q->sched_debugfs_dir = NULL;
-	q->debugfs_dir = NULL;
 }
 
 static void blk_mq_debugfs_register_ctx(struct blk_mq_hw_ctx *hctx,

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 561624d4cc4e..4e0c00a88c99 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c

@@ -918,6 +918,7 @@ static void blk_release_queue(struct kobject *kobj)
 
 	blk_trace_shutdown(q);
 
+	blk_queue_debugfs_unregister(q);
 	if (queue_is_mq(q))
 		blk_mq_debugfs_unregister(q);
 

@@ -989,6 +990,8 @@ int blk_register_queue(struct gendisk *disk)
 		goto unlock;
 	}
 
+	blk_queue_debugfs_register(q, kobject_name(q->kobj.parent));
+
 	if (queue_is_mq(q)) {
 		__blk_mq_register_dev(dev, q);
 		blk_mq_debugfs_register(q);

diff --git a/block/blk.h b/block/blk.h
index ee309233f95e..300b8526066b 100644
--- a/block/blk.h
+++ b/block/blk.h

@@ -460,10 +460,26 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
 
 #ifdef CONFIG_DEBUG_FS
 void blk_debugfs_register(void);
+void blk_queue_debugfs_unregister(struct request_queue *q);
+void blk_part_debugfs_register(struct hd_struct *p, const char *name);
+void blk_part_debugfs_unregister(struct hd_struct *p);
 #else
 static inline void blk_debugfs_register(void)
 {
 }
+
+static inline void blk_queue_debugfs_unregister(struct request_queue *q)
+{
+}
+
+static inline void blk_part_debugfs_register(struct hd_struct *p,
+					     const char *name)
+{
+}
+
+static inline void blk_part_debugfs_unregister(struct hd_struct *p)
+{
+}
 #endif /* CONFIG_DEBUG_FS */
 
 #endif /* BLK_INTERNAL_H */

diff --git a/block/bsg.c b/block/bsg.c
index d7bae94b64d9..bfb1036858c4 100644
--- a/block/bsg.c
+++ b/block/bsg.c

@@ -503,6 +503,8 @@ static int __init bsg_init(void)
 	if (ret)
 		goto unregister_chrdev;
 
+	blk_debugfs_register_bsg();
+
 	printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
 	       " loaded (major %d)\n", bsg_major);
 	return 0;

diff --git a/block/partitions/core.c b/block/partitions/core.c
index 297004fd2264..4d2a130e6055 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c

@@ -10,6 +10,7 @@
 #include <linux/vmalloc.h>
 #include <linux/blktrace_api.h>
 #include <linux/raid/detect.h>
+#include <linux/debugfs.h>
 #include "check.h"
 
 static int (*check_part[])(struct parsed_partitions *) = {

@@ -320,6 +321,9 @@ void delete_partition(struct gendisk *disk, struct hd_struct *part)
 	 *  we have to hold the disk device
 	 */
 	get_device(disk_to_dev(part_to_disk(part)));
+#ifdef CONFIG_DEBUG_FS
+	debugfs_remove(part->debugfs_sym);
+#endif

 	rcu_assign_pointer(ptbl->part[part->partno], NULL);
 	kobject_put(part->holder_dir);
 	device_del(part_to_dev(part));

@@ -460,6 +464,11 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
 	/* everything is up and running, commence */
 	rcu_assign_pointer(ptbl->part[partno], p);
 
+#ifdef CONFIG_DEBUG_FS
+	p->debugfs_sym = blk_queue_debugfs_symlink(disk->queue, dev_name(pdev),
+						   disk->disk_name);
+#endif

+
 	/* suppress uevent if the disk suppresses it */
 	if (!dev_get_uevent_suppress(ddev))
 		kobject_uevent(&pdev->kobj, KOBJ_ADD);

diff --git a/drivers/scsi/ch.c b/drivers/scsi/ch.c
index cb74ab1ae5a4..5dfabc04bfef 100644
--- a/drivers/scsi/ch.c
+++ b/drivers/scsi/ch.c

@@ -971,6 +971,7 @@ static int ch_probe(struct device *dev)
 
 	mutex_unlock(&ch->lock);
 	dev_set_drvdata(dev, ch);
+	blk_queue_debugfs_register(sd->request_queue, dev_name(class_dev));
 	sdev_printk(KERN_INFO, sd, "Attached scsi changer %s\n", ch->name);
 
 	return 0;

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 20472aaaf630..6fa201086e59 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c

@@ -47,6 +47,7 @@ static int sg_version_num = 30536;	/* 2 digits for each component */
 #include <linux/ratelimit.h>
 #include <linux/uio.h>
 #include <linux/cred.h> /* for sg_check_file_access() */
+#include <linux/debugfs.h>
 
 #include "scsi.h"
 #include <scsi/scsi_dbg.h>

@@ -169,6 +170,10 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
 	struct gendisk *disk;
 	struct cdev * cdev;	/* char_dev [sysfs: /sys/cdev/major/sg<n>] */
 	struct kref d_ref;
+#ifdef CONFIG_DEBUG_FS
+	bool debugfs_set;
+	struct dentry *debugfs_sym;
+#endif
 } Sg_device;
 
 /* tasklet or soft irq callback */

@@ -914,6 +919,72 @@ static int put_compat_request_table(struct compat_sg_req_info __user *o,
 }
 #endif
 
+#ifdef CONFIG_DEBUG_FS
+/*
+ * For scsi-generic devices like TYPE_DISK will re-use the scsi_device
+ * request_queue on their driver for their disk and later device_add_disk() it,
+ * we want its respective scsi-generic debugfs_dir to just be a symlink to the
+ * one created on the real scsi device probe.
+ *
+ * We use this on the ioctl path instead of sg_add_device() since some driver
+ * probes can run asynchronously. Such is the case for scsi devices of
+ * TYPE_DISK, and the class interface currently has no callbacks once a device
+ * driver probe has completed its probe. We don't use wait_for_device_probe()
+ * on sg_add_device() as that would defeat the purpose of using asynchronous
+ * probe.
+ */
+static void sg_init_blktrace_setup(Sg_device *sdp)
+{
+	struct scsi_device *scsidp = sdp->device;
+	struct device *scsi_dev = &scsidp->sdev_gendev;
+	struct gendisk *sg_disk = sdp->disk;
+	struct request_queue *q = scsidp->request_queue;
+
+	/*
+	 * Although debugfs is used for debugging purposes and we
+	 * typically don't care about the return value, we do here
+	 * because we use it for userspace to ensure blktrace works.
+	 *
+	 * Instead of always just checking for the return value though,
+	 * just try setting this once, if the first time failed we don't
+	 * try again.
+	 */
+	if (sdp->debugfs_set)
+		return;
+
+	switch (sdp->device->type) {
+	case TYPE_RAID:
+		/*
+		 * We do the registration for bsg here to keep bsg scsi_device
+		 * opaque. If bsg is disabled we just create the debugfs_dir on
+		 * the base block debugfs_dir and scsi-generic symlinks to it.
+		 */
+		blk_queue_debugfs_register_bsg(q, dev_name(scsi_dev));
+		sdp->debugfs_sym =
+			blk_queue_debugfs_bsg_symlink(q,
+						      sg_disk->disk_name,
+						      dev_name(scsi_dev));
+		break;
+	default:
+		/*
+		 * We don't know scsi_device probed device name (this is
+		 * different from the scsi_device name). This is opaque to
+		 * scsi-generic, so we use the request_queue to infer the name
+		 * based on the set debugfs_dir.
+		 */
+		sdp->debugfs_sym = blk_queue_debugfs_symlink(q,
+							     sg_disk->disk_name,
+							     NULL);
+		break;
+	}
+	sdp->debugfs_set = true;
+}
+#else
+static void sg_init_blktrace_setup(Sg_device *sdp)
+{
+}
+#endif
+
 static long
 sg_ioctl_common(struct file *filp, Sg_device *sdp, Sg_fd *sfp,
 		unsigned int cmd_in, void __user *p)

@@ -1117,6 +1188,7 @@ sg_ioctl_common(struct file *filp, Sg_device *sdp, Sg_fd *sfp,
 		return put_user(max_sectors_bytes(sdp->device->request_queue),
 				ip);
 	case BLKTRACESETUP:
+		sg_init_blktrace_setup(sdp);
 		return blk_trace_setup(sdp->device->request_queue,
 				       sdp->disk->disk_name,
 				       MKDEV(SCSI_GENERIC_MAJOR, sdp->index),

@@ -1644,6 +1716,9 @@ sg_remove_device(struct device *cl_dev, struct class_interface *cl_intf)
 
 	sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic");
 	device_destroy(sg_sysfs_class, MKDEV(SCSI_GENERIC_MAJOR, sdp->index));
+#ifdef CONFIG_DEBUG_FS
+	debugfs_remove(sdp->debugfs_sym);
+#endif