ksmbd: set the range of bytes to zero without extending file size in FSCTL_ZERO_DATA

generic/091, 263 test failed since commit f66f8b94 ("cifs: when
extending a file with falloc we should make files not-sparse").
FSCTL_ZERO_DATA sets the range of bytes to zero without extending file
size. The VFS_FALLOCATE_FL_KEEP_SIZE flag should be used even on
non-sparse files.

Cc: stable@vger.kernel.org
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/vfs.c

@@ -1015,7 +1015,9 @@ int ksmbd_vfs_zero_data(struct ksmbd_work *work, struct ksmbd_file *fp,
 				     FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 				     off, len);
 
-	return vfs_fallocate(fp->filp, FALLOC_FL_ZERO_RANGE, off, len);
+	return vfs_fallocate(fp->filp,
+			     FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE,
+			     off, len);
 }
 
 int ksmbd_vfs_fqar_lseek(struct ksmbd_file *fp, loff_t start, loff_t length,