os/bluestore: end scope of std::hex properly; convert csum error to EIO

os/bluestore: end scope of std::hex properly; convert csum error to EIO

Mark's comments:

This passed "ceph_test_objectstore --gtest_filter=*/2".
This PR did not appear to have a significant impact on performance tests.

Closes #10225

os/bluestore: end scope of std::hex properly

To avoid side-effects by accident.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
os/bluestore: convert csum error to EIO

The verify_csum() method either returns -1 or -EOPNOTSUPP, which
is not very proper and difficult for user understanding.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
os/bluestore: assert lextent is shared

Otherwise we are risking of accessing violation.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
os/bluestore: drop duplicated assignment of result code

These two methods never fail actually.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
os/bluestore: improve _do_read() a little

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
os/bluestore: assert decoding of shard of key to be successful

Otherwise we are risking of acessing null pointer.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>