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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 09:04:35 +1200 |
| commit | 12529028a4e55eb0500477d2589eec625466facf (patch) | |
| tree | 7717e9947b582401c2d5c0ea57f7000c736a3e60 /src/backend/access/gin/ginfast.c | |
| parent | d03d9a2614fd58d4a9e90107f1700952333ce2a2 (diff) | |
| download | postgresql-12529028a4e55eb0500477d2589eec625466facf.tar.gz postgresql-12529028a4e55eb0500477d2589eec625466facf.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
Diffstat (limited to 'src/backend/access/gin/ginfast.c')
| -rw-r--r-- | src/backend/access/gin/ginfast.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c index ca7d770d864..eb6c5548318 100644 --- a/src/backend/access/gin/ginfast.c +++ b/src/backend/access/gin/ginfast.c @@ -245,9 +245,10 @@ 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, GIN_METAPAGE_BLKNO); if (collector->sumsize + collector->ntuples * sizeof(ItemIdData) > GinListPageSize) { @@ -291,6 +292,8 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) LockBuffer(metabuffer, GIN_EXCLUSIVE); metadata = GinPageGetMeta(metapage); + CheckForSerializableConflictIn(index, NULL, GIN_METAPAGE_BLKNO); + if (metadata->head == InvalidBlockNumber) { /* @@ -353,6 +356,8 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) char *ptr; char *collectordata; + CheckForSerializableConflictIn(index, NULL, GIN_METAPAGE_BLKNO); + buffer = ReadBuffer(index, metadata->tail); LockBuffer(buffer, GIN_EXCLUSIVE); page = BufferGetPage(buffer); |