vfs: call vfs_clone_file_range() under freeze protection

Move sb_start_write()/sb_end_write() out of the vfs helper and up into the
ioctl handler.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/ioctl.c

@@ -226,7 +226,7 @@ static long ioctl_file_clone(struct file *dst_file, unsigned long srcfd,
 	ret = -EXDEV;
 	if (src_file.file->f_path.mnt != dst_file->f_path.mnt)
 		goto fdput;
-	ret = vfs_clone_file_range(src_file.file, off, dst_file, destoff, olen);
+	ret = do_clone_file_range(src_file.file, off, dst_file, destoff, olen);
 fdput:
 	fdput(src_file);
 	return ret;

fs/nfsd/vfs.c

@@ -509,8 +509,7 @@ __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
 __be32 nfsd4_clone_file_range(struct file *src, u64 src_pos, struct file *dst,
 		u64 dst_pos, u64 count)
 {
-	return nfserrno(vfs_clone_file_range(src, src_pos, dst, dst_pos,
-			count));
+	return nfserrno(do_clone_file_range(src, src_pos, dst, dst_pos, count));
 }
 
 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,

fs/read_write.c

@@ -1687,16 +1687,13 @@ int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 	if (pos_in + len > i_size_read(inode_in))
 		return -EINVAL;
 
-	sb_start_write(inode_out->i_sb);
-
 	ret = file_in->f_op->clone_file_range(file_in, pos_in,
 			file_out, pos_out, len);
 	if (!ret) {
 		fsnotify_access(file_in);
 		fsnotify_modify(file_out);
 	}
 
-	sb_end_write(inode_out->i_sb);
 	return ret;
 }
 EXPORT_SYMBOL(vfs_clone_file_range);

include/linux/fs.h

@@ -1783,6 +1783,19 @@ extern int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 extern int vfs_dedupe_file_range(struct file *file,
 				 struct file_dedupe_range *same);
 
+static inline int do_clone_file_range(struct file *file_in, loff_t pos_in,
+				      struct file *file_out, loff_t pos_out,
+				      u64 len)
+{
+	int ret;
+
+	sb_start_write(file_inode(file_out)->i_sb);
+	ret = vfs_clone_file_range(file_in, pos_in, file_out, pos_out, len);
+	sb_end_write(file_inode(file_out)->i_sb);
+
+	return ret;
+}
+
 struct super_operations {
    	struct inode *(*alloc_inode)(struct super_block *sb);
 	void (*destroy_inode)(struct inode *);