Btrfs: pass root object into btrfs_ioctl_{start, wait}_sync()

Since we have gotten the root in the caller, just pass it into
btrfs_ioctl_{start, wait}_sync() directly.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/ioctl.c

@@ -3058,9 +3058,9 @@ long btrfs_ioctl_trans_end(struct file *file)
 	return 0;
 }
 
-static noinline long btrfs_ioctl_start_sync(struct file *file, void __user *argp)
+static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
+					    void __user *argp)
 {
-	struct btrfs_root *root = BTRFS_I(file->f_dentry->d_inode)->root;
 	struct btrfs_trans_handle *trans;
 	u64 transid;
 	int ret;
@@ -3081,9 +3081,9 @@ static noinline long btrfs_ioctl_start_sync(struct file *file, void __user *argp
 	return 0;
 }
 
-static noinline long btrfs_ioctl_wait_sync(struct file *file, void __user *argp)
+static noinline long btrfs_ioctl_wait_sync(struct btrfs_root *root,
+					   void __user *argp)
 {
-	struct btrfs_root *root = BTRFS_I(file->f_dentry->d_inode)->root;
 	u64 transid;
 
 	if (argp) {
@@ -3843,9 +3843,9 @@ long btrfs_ioctl(struct file *file, unsigned int
 		btrfs_sync_fs(file->f_dentry->d_sb, 1);
 		return 0;
 	case BTRFS_IOC_START_SYNC:
-		return btrfs_ioctl_start_sync(file, argp);
+		return btrfs_ioctl_start_sync(root, argp);
 	case BTRFS_IOC_WAIT_SYNC:
-		return btrfs_ioctl_wait_sync(file, argp);
+		return btrfs_ioctl_wait_sync(root, argp);
 	case BTRFS_IOC_SCRUB:
 		return btrfs_ioctl_scrub(root, argp);
 	case BTRFS_IOC_SCRUB_CANCEL: