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fix(extent-map): MCOL-5559 This patch extends the scope of the crit section to cover remap operation to avoid access races running EMIndex operations

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This commit is contained in:
Roman Nozdrin
2023-08-22 08:36:37 +00:00
parent 74647cd90c
commit 7e746ad90c
2 changed files with 45 additions and 9 deletions
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52
versioning/BRM/extentmap.cpp
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@ -2080,20 +2080,54 @@ void ExtentMap::grabEMIndex(OPS op)
} }
else else
{ {
// Sending down current Managed Shmem size. If EMIndexImpl instance size doesn't match if (op == READ)
// fEMIndexShminfo->allocdSize makeExtentMapIndexImpl will remap managed shmem segment. {
fPExtMapIndexImpl_ = fMST.getTable_upgrade(MasterSegmentTable::EMIndex);
ExtentMapIndexImpl::makeExtentMapIndexImpl(getInitialEMIndexShmkey(), fEMIndexShminfo->allocdSize); emIndexLocked = true;
if (r_only) // Sending down current Managed Shmem size. If EMIndexImpl instance size doesn't match
fPExtMapIndexImpl_->makeReadOnly(); // fEMIndexShminfo->allocdSize makeExtentMapIndexImpl will remap managed shmem segment.
fPExtMapIndexImpl_ = ExtentMapIndexImpl::makeExtentMapIndexImpl(getInitialEMIndexShmkey(),
fEMIndexShminfo->allocdSize);
if (r_only)
fPExtMapIndexImpl_->makeReadOnly();
emIndexLocked = false;
fMST.getTable_downgrade(MasterSegmentTable::EMIndex);
}
else
{
fPExtMapIndexImpl_ = ExtentMapIndexImpl::makeExtentMapIndexImpl(getInitialEMIndexShmkey(),
fEMIndexShminfo->allocdSize);
if (r_only)
fPExtMapIndexImpl_->makeReadOnly();
}
} }
} }
else if (fPExtMapIndexImpl_->getShmemImplSize() != (unsigned)fEMIndexShminfo->allocdSize) else if (fPExtMapIndexImpl_->getShmemImplSize() != (unsigned)fEMIndexShminfo->allocdSize)
{ {
fPExtMapIndexImpl_->refreshShm(); if (op == READ)
fPExtMapIndexImpl_ = {
ExtentMapIndexImpl::makeExtentMapIndexImpl(getInitialEMIndexShmkey(), fEMIndexShminfo->allocdSize); fMST.getTable_upgrade(MasterSegmentTable::EMIndex);
emIndexLocked = true;
fPExtMapIndexImpl_->refreshShm();
fPExtMapIndexImpl_ =
ExtentMapIndexImpl::makeExtentMapIndexImpl(getInitialEMIndexShmkey(), fEMIndexShminfo->allocdSize);
emIndexLocked = false;
fMST.getTable_downgrade(MasterSegmentTable::EMIndex);
}
else
{
fPExtMapIndexImpl_->refreshShm();
fPExtMapIndexImpl_ =
ExtentMapIndexImpl::makeExtentMapIndexImpl(getInitialEMIndexShmkey(), fEMIndexShminfo->allocdSize);
}
} }
} }

2
versioning/BRM/extentmap.h
View File

@ -372,6 +372,8 @@ class ExtentMapIndexImpl
{ {
if (fInstance_) if (fInstance_)
{ {
// effectively umpas a mapped managed shmem segment changing the segment VA address
// when mapped next time.
delete fInstance_; delete fInstance_;
fInstance_ = nullptr; fInstance_ = nullptr;
} }