1 files changed, 28 insertions, 10 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index f5958f4..028d9fb 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -300,10 +300,10 @@ static struct super_operations bdev_sops = {
 	.clear_inode = bdev_clear_inode,
 };
 
-static struct super_block *bd_get_sb(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data)
+static int bd_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
-	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576);
+	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
 }
 
 static struct file_system_type bd_type = {
@@ -414,21 +414,31 @@ EXPORT_SYMBOL(bdput);
 static struct block_device *bd_acquire(struct inode *inode)
 {
 	struct block_device *bdev;
+
 	spin_lock(&bdev_lock);
 	bdev = inode->i_bdev;
-	if (bdev && igrab(bdev->bd_inode)) {
+	if (bdev) {
+		atomic_inc(&bdev->bd_inode->i_count);
 		spin_unlock(&bdev_lock);
 		return bdev;
 	}
 	spin_unlock(&bdev_lock);
+
 	bdev = bdget(inode->i_rdev);
 	if (bdev) {
 		spin_lock(&bdev_lock);
-		if (inode->i_bdev)
-			__bd_forget(inode);
-		inode->i_bdev = bdev;
-		inode->i_mapping = bdev->bd_inode->i_mapping;
-		list_add(&inode->i_devices, &bdev->bd_inodes);
+		if (!inode->i_bdev) {
+			/*
+			 * We take an additional bd_inode->i_count for inode,
+			 * and it's released in clear_inode() of inode.
+			 * So, we can access it via ->i_mapping always
+			 * without igrab().
+			 */
+			atomic_inc(&bdev->bd_inode->i_count);
+			inode->i_bdev = bdev;
+			inode->i_mapping = bdev->bd_inode->i_mapping;
+			list_add(&inode->i_devices, &bdev->bd_inodes);
+		}
 		spin_unlock(&bdev_lock);
 	}
 	return bdev;
@@ -438,10 +448,18 @@ static struct block_device *bd_acquire(struct inode *inode)
 
 void bd_forget(struct inode *inode)
 {
+	struct block_device *bdev = NULL;
+
 	spin_lock(&bdev_lock);
-	if (inode->i_bdev)
+	if (inode->i_bdev) {
+		if (inode->i_sb != blockdev_superblock)
+			bdev = inode->i_bdev;
 		__bd_forget(inode);
+	}
 	spin_unlock(&bdev_lock);
+
+	if (bdev)
+		iput(bdev->bd_inode);
 }
 
 int bd_claim(struct block_device *bdev, void *holder)