Fix nullptr access and race to fault_fs_guard

[hx235]

Context/Summary:

There are a couple places where we forgot to check fault_fs_guard before accessing it. So we can see something like this occasionally

=138831==Hint: address points to the zero page.
SCARINESS: 10 (null-deref)
AddressSanitizer:DEADLYSIGNAL
    #0 0x18b9e0b in rocksdb::ThreadLocalPtr::Get() const fbcode/internal_repo_rocksdb/repo/util/thread_local.cc:503
    #1 0x83d8b7 in rocksdb::StressTest::TestCompactRange(rocksdb::ThreadState*, long, rocksdb::Slice const&, rocksdb::ColumnFamilyHandle*) fbcode/internal_repo_rocksdb/repo/utilities/fault_injection_fs.h

Also accessing of io_activties_exempted_from_fault_injection.find not fully synced so we see the following

WARNING: ThreadSanitizer: data race (pid=90939)
  Write of size 8 at 0x7b4c000004d0 by thread T762 (mutexes: write M0):
    #0 std::_Rb_tree<rocksdb::Env::IOActivity, rocksdb::Env::IOActivity, std::_Identity<rocksdb::Env::IOActivity>, std::less<rocksdb::Env::IOActivity>, std::allocator<rocksdb::Env::IOActivity>>::operator=(std::_Rb_tree<rocksdb::Env::IOActivity, rocksdb::Env::IOActivity, std::_Identity<rocksdb::Env::IOActivity>, std::less<rocksdb::Env::IOActivity>, std::allocator<rocksdb::Env::IOActivity>> const&) fbcode/third-party-buck/platform010/build/libgcc/include/c++/trunk/bits/stl_tree.h:208 (db_stress+0x411c32) (BuildId: b803e5aca22c6b080defed8e85b7bfec)
    #1 rocksdb::DbStressListener::OnErrorRecoveryCompleted(rocksdb::Status) fbcode/third-party-buck/platform010/build/libgcc/include/c++/trunk/bits/stl_set.h:298 (db_stress+0x4112e5) (BuildId: b803e5aca22c6b080defed8e85b7bfec)
    #2 rocksdb::EventHelpers::NotifyOnErrorRecoveryEnd(std::vector<std::shared_ptr<rocksdb::EventListener>, std::allocator<std::shared_ptr<rocksdb::EventListener>>> const&, rocksdb::Status const&, rocksdb::Status const&, rocksdb::InstrumentedMutex*) fbcode/internal_repo_rocksdb/repo/db/event_helpers.cc:239 (db_stress+0xa09d60) (BuildId: b803e5aca22c6b080defed8e85b7bfec)
 
  Previous read of size 8 at 0x7b4c000004d0 by thread T131 (mutexes: write M1):
    #0 rocksdb::FaultInjectionTestFS::MaybeInjectThreadLocalError(rocksdb::FaultInjectionIOType, rocksdb::IOOptions const&, rocksdb::FaultInjectionTestFS::ErrorOperation, rocksdb::Slice*, bool, char*, bool, bool*) fbcode/third-party-buck/platform010/build/libgcc/include/c++/trunk/bits/stl_tree.h:798 (db_stress+0xf7d0f3) (BuildId: b803e5aca22c6b080defed8e85b7bfec)

Test:
CI

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[hx235]

Pre-existing CI failure in StressTest::TestIterateAttributeGroups

[jowlyzhang]

LGTM! Thanks for the fix!

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@hx235 has updated the pull request. You must reimport the pull request before landing.

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@hx235 has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@hx235 has updated the pull request. You must reimport the pull request before landing.

[facebook-github-bot]

@hx235 has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@hx235 has updated the pull request. You must reimport the pull request before landing.

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@hx235 has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

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@hx235 merged this pull request in 56f7ef5.