mtd: create per-device and module-scope debugfs entries

Several MTD devices are using debugfs entries created in the root.
This commit provides the means for a standardized subtree, creating
one "mtd" entry at root, and one entry per device inside it, named
after the device.
The tree is registered in add_mtd_device, and released in
del_mtd_device.
Devices docg3, mtdswap and nandsim were updated to use this subtree
instead of custom ones, and their entries were prefixed with the
drivers' names.

Signed-off-by: Mario J. Rugiero <mrugiero@gmail.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 4 insertions, 14 deletions

diff --git a/drivers/mtd/mtdswap.c b/drivers/mtd/mtdswap.c
index f12879a3d4ff..6b17932fe557 100644
--- a/drivers/mtd/mtdswap.c
+++ b/drivers/mtd/mtdswap.c
@@ -138,8 +138,6 @@ struct mtdswap_dev {
 
 	char *page_buf;
 	char *oob_buf;
-
-	struct dentry *debugfs_root;
 };
 
 struct mtdswap_oobdata {
@@ -1318,26 +1316,19 @@ static int mtdswap_add_debugfs(struct mtdswap_dev *d)
 	struct gendisk *gd = d->mbd_dev->disk;
 	struct device *dev = disk_to_dev(gd);
 
-	struct dentry *root;
+	struct dentry *root = d->mtd->dbg.dfs_dir;
 	struct dentry *dent;
 
-	root = debugfs_create_dir(gd->disk_name, NULL);
-	if (IS_ERR(root))
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
 		return 0;
 
-	if (!root) {
-		dev_err(dev, "failed to initialize debugfs\n");
+	if (IS_ERR_OR_NULL(root))
 		return -1;
-	}
-
-	d->debugfs_root = root;
 
-	dent = debugfs_create_file("stats", S_IRUSR, root, d,
+	dent = debugfs_create_file("mtdswap_stats", S_IRUSR, root, d,
 				&mtdswap_fops);
 	if (!dent) {
 		dev_err(d->dev, "debugfs_create_file failed\n");
-		debugfs_remove_recursive(root);
-		d->debugfs_root = NULL;
 		return -1;
 	}
 
@@ -1540,7 +1531,6 @@ static void mtdswap_remove_dev(struct mtd_blktrans_dev *dev)
 {
 	struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
 
-	debugfs_remove_recursive(d->debugfs_root);
 	del_mtd_blktrans_dev(dev);
 	mtdswap_cleanup(d);
 	kfree(d);