cherry-pick #1918 to release-4.0
You can switch your code base to this Pull Request by using git-extras:

# In tics repo:
git pr https://github.com/pingcap/tics/pull/1924

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tics.git pr/1924:release-4.0-46864eb2e244

What problem does this PR solve?

Issue Number: close #1138

Problem Summary:
There may be broken dmfile left on disk under a special scenario.

1. After creating a readable dmfile, if tiflash crash before the corresponding stable is applied, there will be a directory like dmf_100 left on disk.
2. When restart tiflash again, tiflash will create .tmp.dmf_100 and try to rename it to dmf_100 after writing is finished. So it will try to remove the old dmf_100 directory, but this removal is not atomic. So when tiflash crash again in the middle of the removal, the will be a broken dmfile left on disk. And tiflash will never be able to restart again.

What is changed and how it works?

Rename the dmfile before delete it.

Proposal: xxx

What's Changed:

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch:

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

Release note

• Fix the problem that old dmfile is not removed atomically