1 files changed, 32 insertions, 22 deletions

diff --git a/fs/char_dev.c b/fs/char_dev.c
index d6db933df2b..f77f7702fab 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -20,6 +20,7 @@
 #include <linux/cdev.h>
 #include <linux/mutex.h>
 #include <linux/backing-dev.h>
+#include <linux/tty.h>
 
 #include "internal.h"
 
@@ -39,7 +40,9 @@ struct backing_dev_info directly_mappable_cdev_bdi = {
 #endif
 		/* permit direct mmap, for read, write or exec */
 		BDI_CAP_MAP_DIRECT |
-		BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
+		BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
+		/* no writeback happens */
+		BDI_CAP_NO_ACCT_AND_WRITEBACK),
 };
 
 static struct kobj_map *cdev_map;
@@ -56,7 +59,7 @@ static struct char_device_struct {
 } *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
 
 /* index in the above */
-static inline int major_to_index(int major)
+static inline int major_to_index(unsigned major)
 {
 	return major % CHRDEV_MAJOR_HASH_SIZE;
 }
@@ -269,7 +272,7 @@ int __register_chrdev(unsigned int major, unsigned int baseminor,
 	cd = __register_chrdev_region(major, baseminor, count, name);
 	if (IS_ERR(cd))
 		return PTR_ERR(cd);
-	
+
 	cdev = cdev_alloc();
 	if (!cdev)
 		goto out2;
@@ -277,7 +280,7 @@ int __register_chrdev(unsigned int major, unsigned int baseminor,
 	cdev->owner = fops->owner;
 	cdev->ops = fops;
 	kobject_set_name(&cdev->kobj, "%s", name);
-		
+
 	err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
 	if (err)
 		goto out;
@@ -365,6 +368,7 @@ void cdev_put(struct cdev *p)
  */
 static int chrdev_open(struct inode *inode, struct file *filp)
 {
+	const struct file_operations *fops;
 	struct cdev *p;
 	struct cdev *new = NULL;
 	int ret = 0;
@@ -397,12 +401,13 @@ static int chrdev_open(struct inode *inode, struct file *filp)
 		return ret;
 
 	ret = -ENXIO;
-	filp->f_op = fops_get(p->ops);
-	if (!filp->f_op)
+	fops = fops_get(p->ops);
+	if (!fops)
 		goto out_cdev_put;
 
+	replace_fops(filp, fops);
 	if (filp->f_op->open) {
-		ret = filp->f_op->open(inode,filp);
+		ret = filp->f_op->open(inode, filp);
 		if (ret)
 			goto out_cdev_put;
 	}
@@ -414,18 +419,6 @@ static int chrdev_open(struct inode *inode, struct file *filp)
 	return ret;
 }
 
-int cdev_index(struct inode *inode)
-{
-	int idx;
-	struct kobject *kobj;
-
-	kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
-	if (!kobj)
-		return -1;
-	kobject_put(kobj);
-	return idx;
-}
-
 void cd_forget(struct inode *inode)
 {
 	spin_lock(&cdev_lock);
@@ -453,6 +446,7 @@ static void cdev_purge(struct cdev *cdev)
  */
 const struct file_operations def_chr_fops = {
 	.open = chrdev_open,
+	.llseek = noop_llseek,
 };
 
 static struct kobject *exact_match(dev_t dev, int *part, void *data)
@@ -479,9 +473,19 @@ static int exact_lock(dev_t dev, void *data)
  */
 int cdev_add(struct cdev *p, dev_t dev, unsigned count)
 {
+	int error;
+
 	p->dev = dev;
 	p->count = count;
-	return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
+
+	error = kobj_map(cdev_map, dev, count, NULL,
+			 exact_match, exact_lock, p);
+	if (error)
+		return error;
+
+	kobject_get(p->kobj.parent);
+
+	return 0;
 }
 
 static void cdev_unmap(dev_t dev, unsigned count)
@@ -506,14 +510,20 @@ void cdev_del(struct cdev *p)
 static void cdev_default_release(struct kobject *kobj)
 {
 	struct cdev *p = container_of(kobj, struct cdev, kobj);
+	struct kobject *parent = kobj->parent;
+
 	cdev_purge(p);
+	kobject_put(parent);
 }
 
 static void cdev_dynamic_release(struct kobject *kobj)
 {
 	struct cdev *p = container_of(kobj, struct cdev, kobj);
+	struct kobject *parent = kobj->parent;
+
 	cdev_purge(p);
 	kfree(p);
+	kobject_put(parent);
 }
 
 static struct kobj_type ktype_cdev_default = {
@@ -566,7 +576,8 @@ static struct kobject *base_probe(dev_t dev, int *part, void *data)
 void __init chrdev_init(void)
 {
 	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
-	bdi_init(&directly_mappable_cdev_bdi);
+	if (bdi_init(&directly_mappable_cdev_bdi))
+		panic("Failed to init directly mappable cdev bdi");
 }
 
 
@@ -578,7 +589,6 @@ EXPORT_SYMBOL(cdev_init);
 EXPORT_SYMBOL(cdev_alloc);
 EXPORT_SYMBOL(cdev_del);
 EXPORT_SYMBOL(cdev_add);
-EXPORT_SYMBOL(cdev_index);
 EXPORT_SYMBOL(__register_chrdev);
 EXPORT_SYMBOL(__unregister_chrdev);
 EXPORT_SYMBOL(directly_mappable_cdev_bdi);