block, badblocks: introduce devm_init_badblocks

Provide a devres interface for initializing a badblocks instance.  The
pmem driver has several scenarios where it will be beneficial to have
this structure automatically freed when the device is disabled / fails
probe.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

block/badblocks.c

@@ -17,6 +17,7 @@
 
 #include <linux/badblocks.h>
 #include <linux/seqlock.h>
+#include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/stddef.h>
@@ -522,24 +523,20 @@ ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,
 }
 EXPORT_SYMBOL_GPL(badblocks_store);
 
-/**
- * badblocks_init() - initialize the badblocks structure
- * @bb:		the badblocks structure that holds all badblock information
- * @enable:	weather to enable badblocks accounting
- *
- * Return:
- *  0: success
- *  -ve errno: on error
- */
-int badblocks_init(struct badblocks *bb, int enable)
+static int __badblocks_init(struct device *dev, struct badblocks *bb,
+		int enable)
 {
+	bb->dev = dev;
 	bb->count = 0;
 	if (enable)
 		bb->shift = 0;
 	else
 		bb->shift = -1;
+	if (dev)
+		bb->page = devm_kzalloc(dev, PAGE_SIZE, GFP_KERNEL);
+	else
 		bb->page = kzalloc(PAGE_SIZE, GFP_KERNEL);
-	if (bb->page == (u64 *)0) {
+	if (!bb->page) {
 		bb->shift = -1;
 		return -ENOMEM;
 	}
@@ -547,8 +544,30 @@ int badblocks_init(struct badblocks *bb, int enable)
 
 	return 0;
 }
+
+/**
+ * badblocks_init() - initialize the badblocks structure
+ * @bb:		the badblocks structure that holds all badblock information
+ * @enable:	weather to enable badblocks accounting
+ *
+ * Return:
+ *  0: success
+ *  -ve errno: on error
+ */
+int badblocks_init(struct badblocks *bb, int enable)
+{
+	return __badblocks_init(NULL, bb, enable);
+}
 EXPORT_SYMBOL_GPL(badblocks_init);
 
+int devm_init_badblocks(struct device *dev, struct badblocks *bb)
+{
+	if (!bb)
+		return -EINVAL;
+	return __badblocks_init(dev, bb, 1);
+}
+EXPORT_SYMBOL_GPL(devm_init_badblocks);
+
 /**
  * badblocks_exit() - free the badblocks structure
  * @bb:		the badblocks structure that holds all badblock information
@@ -557,6 +576,9 @@ void badblocks_exit(struct badblocks *bb)
 {
 	if (!bb)
 		return;
+	if (bb->dev)
+		devm_kfree(bb->dev, bb->page);
+	else
 		kfree(bb->page);
 	bb->page = NULL;
 }

include/linux/badblocks.h

@@ -2,6 +2,7 @@
 #define _LINUX_BADBLOCKS_H
 
 #include <linux/seqlock.h>
+#include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/stddef.h>
 #include <linux/types.h>
@@ -23,6 +24,7 @@
 #define MAX_BADBLOCKS	(PAGE_SIZE/8)
 
 struct badblocks {
+	struct device *dev;	/* set by devm_init_badblocks */
 	int count;		/* count of bad blocks */
 	int unacked_exist;	/* there probably are unacknowledged
 				 * bad blocks.  This is only cleared
@@ -49,5 +51,15 @@ ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,
 			int unack);
 int badblocks_init(struct badblocks *bb, int enable);
 void badblocks_exit(struct badblocks *bb);
-
+struct device;
+int devm_init_badblocks(struct device *dev, struct badblocks *bb);
+static inline void devm_exit_badblocks(struct device *dev, struct badblocks *bb)
+{
+	if (bb->dev != dev) {
+		dev_WARN_ONCE(dev, 1, "%s: badblocks instance not associated\n",
+				__func__);
+		return;
+	}
+	badblocks_exit(bb);
+}
 #endif