In case a discard_cmd is split into several bios, the dc->error
must not be overwritten once an error is reported by a bio. Also,
move it under dc->lock.
Signed-off-by: NSahitya Tummala <stummala@codeaurora.org>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>