[v4,4/8] mtd: ubi: block: use notifier to create ubiblock

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 69fa6fecb8494..e0618bbde3613 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -33,6 +33,7 @@ 
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/namei.h>
 #include <linux/slab.h>
 #include <linux/mtd/ubi.h>
 #include <linux/blkdev.h>
@@ -65,10 +66,10 @@  struct ubiblock_pdu {
 };
 
 /* Numbers of elements set in the @ubiblock_param array */
-static int ubiblock_devs __initdata;
+static int ubiblock_devs;
 
 /* MTD devices specification parameters */
-static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES] __initdata;
+static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES];
 
 struct ubiblock {
 	struct ubi_volume_desc *desc;
@@ -532,6 +533,85 @@  static int ubiblock_resize(struct ubi_volume_info *vi)
 	return 0;
 }
 
+static bool
+match_volume_desc(struct ubi_volume_info *vi, const char *name, int ubi_num, int vol_id)
+{
+	int err, len;
+	struct path path;
+	struct kstat stat;
+
+	if (ubi_num == -1) {
+		/* No ubi num, name must be a vol device path */
+		err = kern_path(name, LOOKUP_FOLLOW, &path);
+		if (err)
+			return false;
+
+		err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
+		path_put(&path);
+		if (err)
+			return false;
+
+		if (!S_ISCHR(stat.mode))
+			return false;
+
+		if (vi->ubi_num != ubi_major2num(MAJOR(stat.rdev)))
+			return false;
+
+		if (vi->vol_id != MINOR(stat.rdev) - 1)
+			return false;
+
+		return true;
+	}
+
+	if (vol_id == -1) {
+		if (vi->ubi_num != ubi_num)
+			return false;
+
+		len = strnlen(name, UBI_VOL_NAME_MAX + 1);
+		if (len < 1 || vi->name_len != len)
+			return false;
+
+		if (strcmp(name, vi->name))
+			return false;
+
+		return true;
+	}
+
+	if (vi->ubi_num != ubi_num)
+		return false;
+
+	if (vi->vol_id != vol_id)
+		return false;
+
+	return true;
+}
+
+static void
+ubiblock_create_from_param(struct ubi_volume_info *vi)
+{
+	int i, ret = 0;
+	struct ubiblock_param *p;
+
+	/*
+	 * Iterate over ubiblock cmdline parameters. If a parameter matches the
+	 * newly added volume create the ubiblock device for it.
+	 */
+	for (i = 0; i < ubiblock_devs; i++) {
+		p = &ubiblock_param[i];
+
+		if (!match_volume_desc(vi, p->name, p->ubi_num, p->vol_id))
+			continue;
+
+		ret = ubiblock_create(vi);
+		if (ret) {
+			pr_err(
+			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d\n",
+			       vi->name, p->ubi_num, p->vol_id, ret);
+		}
+		break;
+	}
+}
+
 static int ubiblock_notify(struct notifier_block *nb,
 			 unsigned long notification_type, void *ns_ptr)
 {
@@ -539,10 +619,7 @@  static int ubiblock_notify(struct notifier_block *nb,
 
 	switch (notification_type) {
 	case UBI_VOLUME_ADDED:
-		/*
-		 * We want to enforce explicit block device creation for
-		 * volumes, so when a volume is added we do nothing.
-		 */
+		ubiblock_create_from_param(&nt->vi);
 		break;
 	case UBI_VOLUME_REMOVED:
 		ubiblock_remove(&nt->vi, true);
@@ -568,56 +645,6 @@  static struct notifier_block ubiblock_notifier = {
 	.notifier_call = ubiblock_notify,
 };
 
-static struct ubi_volume_desc * __init
-open_volume_desc(const char *name, int ubi_num, int vol_id)
-{
-	if (ubi_num == -1)
-		/* No ubi num, name must be a vol device path */
-		return ubi_open_volume_path(name, UBI_READONLY);
-	else if (vol_id == -1)
-		/* No vol_id, must be vol_name */
-		return ubi_open_volume_nm(ubi_num, name, UBI_READONLY);
-	else
-		return ubi_open_volume(ubi_num, vol_id, UBI_READONLY);
-}
-
-static void __init ubiblock_create_from_param(void)
-{
-	int i, ret = 0;
-	struct ubiblock_param *p;
-	struct ubi_volume_desc *desc;
-	struct ubi_volume_info vi;
-
-	/*
-	 * If there is an error creating one of the ubiblocks, continue on to
-	 * create the following ubiblocks. This helps in a circumstance where
-	 * the kernel command-line specifies multiple block devices and some
-	 * may be broken, but we still want the working ones to come up.
-	 */
-	for (i = 0; i < ubiblock_devs; i++) {
-		p = &ubiblock_param[i];
-
-		desc = open_volume_desc(p->name, p->ubi_num, p->vol_id);
-		if (IS_ERR(desc)) {
-			pr_err(
-			       "UBI: block: can't open volume on ubi%d_%d, err=%ld\n",
-			       p->ubi_num, p->vol_id, PTR_ERR(desc));
-			continue;
-		}
-
-		ubi_get_volume_info(desc, &vi);
-		ubi_close_volume(desc);
-
-		ret = ubiblock_create(&vi);
-		if (ret) {
-			pr_err(
-			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d\n",
-			       vi.name, p->ubi_num, p->vol_id, ret);
-			continue;
-		}
-	}
-}
-
 static void ubiblock_remove_all(void)
 {
 	struct ubiblock *next;
@@ -643,18 +670,7 @@  int __init ubiblock_init(void)
 	if (ubiblock_major < 0)
 		return ubiblock_major;
 
-	/*
-	 * Attach block devices from 'block=' module param.
-	 * Even if one block device in the param list fails to come up,
-	 * still allow the module to load and leave any others up.
-	 */
-	ubiblock_create_from_param();
-
-	/*
-	 * Block devices are only created upon user requests, so we ignore
-	 * existing volumes.
-	 */
-	ret = ubi_register_volume_notifier(&ubiblock_notifier, 1);
+	ret = ubi_register_volume_notifier(&ubiblock_notifier, 0);
 	if (ret)
 		goto err_unreg;
 	return 0;