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| author | Thomas Munro <tmunro@postgresql.org> | 2023-07-03 16:20:01 +1200 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2023-07-04 09:21:33 +1200 |
| commit | 255a925d333be9a3d6314e2fe698063eb8e753a6 (patch) | |
| tree | d5e78762bf34f307e7e5d52b15666a368e23c2e3 | |
| parent | 17b8887c29e55e2ac2e04a41a87714a4960484fa (diff) | |
| download | postgresql-255a925d333be9a3d6314e2fe698063eb8e753a6.tar.gz postgresql-255a925d333be9a3d6314e2fe698063eb8e753a6.zip | |
Fix race in SSI interaction with gin fast path.
The ginfast.c code previously checked for conflicts in before locking
the relevant buffer, leaving a window where a RW conflict could be
missed. Re-order.
There was also a place where buffer ID and block number were confused
while trying to predicate-lock a page, noted by visual inspection.
Back-patch to all supported releases. Fixes one more problem discovered
with the reproducer from bug #17949, in this case when Dmitry tried
other index types.
Reported-by: Artem Anisimov <artem.anisimov.255@gmail.com>
Reported-by: Dmitry Dolgov <9erthalion6@gmail.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/17949-a0f17035294a55e2%40postgresql.org
| -rw-r--r-- | src/backend/access/gin/ginfast.c | 9 | ||||
| -rw-r--r-- | src/backend/access/gin/ginget.c | 4 |
2 files changed, 10 insertions, 3 deletions
diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c index a7a49b36fd0..4dcfdf2ac63 100644 --- a/src/backend/access/gin/ginfast.c +++ b/src/backend/access/gin/ginfast.c @@ -244,9 +244,10 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) /* * An insertion to the pending list could logically belong anywhere in the * tree, so it conflicts with all serializable scans. All scans acquire a - * predicate lock on the metabuffer to represent that. + * predicate lock on the metabuffer to represent that. Therefore we'll + * check for conflicts in, but not until we have the page locked and are + * ready to modify the page. */ - CheckForSerializableConflictIn(index, NULL, metabuffer); if (collector->sumsize + collector->ntuples * sizeof(ItemIdData) > GinListPageSize) { @@ -290,6 +291,8 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) LockBuffer(metabuffer, GIN_EXCLUSIVE); metadata = GinPageGetMeta(metapage); + CheckForSerializableConflictIn(index, NULL, metabuffer); + if (metadata->head == InvalidBlockNumber) { /* @@ -352,6 +355,8 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) char *ptr; char *collectordata; + CheckForSerializableConflictIn(index, NULL, metabuffer); + buffer = ReadBuffer(index, metadata->tail); LockBuffer(buffer, GIN_EXCLUSIVE); page = BufferGetPage(buffer); diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c index 1b1869de987..51e3ad5f839 100644 --- a/src/backend/access/gin/ginget.c +++ b/src/backend/access/gin/ginget.c @@ -139,7 +139,9 @@ collectMatchBitmap(GinBtreeData *btree, GinBtreeStack *stack, * Predicate lock entry leaf page, following pages will be locked by * moveRightIfItNeeded() */ - PredicateLockPage(btree->index, stack->buffer, snapshot); + PredicateLockPage(btree->index, + BufferGetBlockNumber(stack->buffer), + snapshot); for (;;) { |