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* [PATCH 2/2] Detect invalid FSM when finding a block.
@ 2024-03-06 08:12 Ronan Dunklau <ronan.dunklau@aiven.io>
0 siblings, 0 replies; 1+ messages in thread
From: Ronan Dunklau @ 2024-03-06 08:12 UTC (permalink / raw)
Whenever the FSM points to a block past the end of the relation, detect
it and fallback to the relation extension mechanism.
This may arise when a FPI for the FSM has been triggered, and we end up
WAL-logging a page of the FSM pointing to newly extended blocks in the
relation which have never been WAL-logged.
---
src/backend/access/heap/hio.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
inline patch 1: src/backend/access/heap/hio.c (+19/-1 lines) download inline-1.patch
diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c
index ccc4c6966a2..1cf4c6354a1 100644
--- a/src/backend/access/heap/hio.c
+++ b/src/backend/access/heap/hio.c
@@ -517,6 +517,7 @@ RelationGetBufferForTuple(Relation relation, Size len,
otherBlock;
bool unlockedTargetBuffer;
bool recheckVmPins;
+ BlockNumber nblocks = InvalidBlockNumber;
len = MAXALIGN(len); /* be conservative */
@@ -583,6 +584,16 @@ RelationGetBufferForTuple(Relation relation, Size len,
* target.
*/
targetBlock = GetPageWithFreeSpace(relation, targetFreeSpace);
+ nblocks = RelationGetNumberOfBlocks(relation);
+ /*
+ * Since relation extension are not wal logged, the fsm could end up
+ * pointing to an unlogged empty segment.
+ * Detect it, and fall back through trying the last page
+ */
+ if (unlikely(targetBlock >= nblocks))
+ {
+ targetBlock = InvalidBlockNumber;
+ }
}
/*
@@ -592,7 +603,8 @@ RelationGetBufferForTuple(Relation relation, Size len,
*/
if (targetBlock == InvalidBlockNumber)
{
- BlockNumber nblocks = RelationGetNumberOfBlocks(relation);
+ if (nblocks == InvalidBlockNumber)
+ nblocks = RelationGetNumberOfBlocks(relation);
if (nblocks > 0)
targetBlock = nblocks - 1;
@@ -761,6 +773,12 @@ loop:
targetBlock,
pageFreeSpace,
targetFreeSpace);
+ /* As above, if the FSM gives us a page past the end of the relation,
+ * give up and fallback to extending the relation */
+ if (nblocks == InvalidBlockNumber)
+ nblocks = RelationGetNumberOfBlocks(relation);
+ if (targetBlock >= nblocks)
+ targetBlock = InvalidBlockNumber;
}
}
--
2.44.0
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2024-03-06 08:12 [PATCH 2/2] Detect invalid FSM when finding a block. Ronan Dunklau <ronan.dunklau@aiven.io>
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