Summary:
Fix the following cases that can cause false alarms in db_stress when read fault injection is
enabled -
1. Turn off corruption/truncation when direct IO is enabled. Since the actual IO size is larger than block size due to alignment requirements, the corruption may not result in a detectable error.
2. Handle the case when the randomly generated string to overwrite the original block is identical to the original.
Tests:
Run db_stress w/ and wo/ direct IO and fault injection turned on
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6777
Reviewed By: zhichao-cao
Differential Revision: D21316734
Pulled By: anand1976
fbshipit-source-id: bf0e6468043063ca81ff877d4bf71d3f296c77aa
b938e6042b