target: don't call an unmap callback if a range length is zero

If a length of a range is zero, it means there is nothing to unmap
and we can skip this range.

Here is one more reason, why we have to skip such ranges.  An unmap
callback calls file_operations->fallocate(), but the man page for the
fallocate syscall says that fallocate(fd, mode, offset, let) returns
EINVAL, if len is zero. It means that file_operations->fallocate() isn't
obligated to handle zero ranges too.

Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Andrei Vagin 2017-12-13 13:55:13 -08:00 committed by Nicholas Bellinger
parent ce512d79d0
commit 9960f85181

View file

@ -1216,9 +1216,11 @@ sbc_execute_unmap(struct se_cmd *cmd)
goto err;
}
ret = ops->execute_unmap(cmd, lba, range);
if (ret)
goto err;
if (range) {
ret = ops->execute_unmap(cmd, lba, range);
if (ret)
goto err;
}
ptr += 16;
size -= 16;